This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------ This file has many users' tips for cutting threads. It also contains some suggestions as to how to remove the remainder of a tap or bolt or screw broken off in a hole. [When searching for the subject of a broken off tap or bolt, also search for the term "broken screw" -- some folks use the term "screw" incorrectly.] Threading in metal may be accomplished in many different ways. The most common threading done by a home hobbyist uses taps and dies; alternatively single point threading on a metal lathe is employed. Sometimes both methods are used to produce a thread. The thread is cut to rough dimensions on the metal lathe, and then is finished with the correct tap or die. Tip: If your part calls for an internal thread that you are going to cut using a tap, consider doing this operation very early in this project part's machining; then if the tap breaks off in the hole, you have the option of discarding the part and starting over on another piece of metal without wasting time trying to get the broken tap out. At this early stage you also have not wasted a lot of time on this part's more complex machining steps. Also see the file "Atlas Chucks General" which has messages on making threaded faceplates and backing plates; more threading information is in the file "Atlas Backing Plates for Chucks". Also for threading on the lathe, there is much discussion about the thread dial's use in the text file "Thread Dial and Half Nuts". For lathes without threading gears, there is an interesting workaround described in the file here Taig Lathe Tips, by John Bentley starting 30 Oct 2003. Very similar to methods used on ornamental turning lathes of the 1800's. Works for any thread size and shape. If you got to this file directly from my HOME PAGE, return there by using your browser's back button. BUT if you came to this file as the result of a web search engine, see many additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/index.html SAFETY WARNING BEWARE: DO NOT ASSUME that any subject matter or procedure or process is safe or correct or appropriate just because it was mentioned in a news/user group or was included in these files or on this site or on any other web site or was published in a magazine or book or video. Working with metals and machinery and chemicals and electrical equipment is inherently dangerous. Wear safety devices and clothing as appropriate. Remove watches, rings, and jewellery -- and secure or remove loose clothing -- before operating any machine. Read, understand and follow the latest operating procedures and safety instructions provided by the manufacturer of your machine or tool or product. If you do not have those most recent official instructions, acquire a copy through the manufacturer before operating or using their product. Where the company no longer exists, use the appropriate news or user group to locate an official copy. Be careful -- original instructions may not meet current safety standards. Updated safety information and operating instructions may also be available through a local club, a local professional in the trade, a local business, or an appropriate government agency. In every case, use your common sense before beginning or taking the next step; and do not proceed if you have any questions or doubts about any procedure, or the safety of any procedure. Follow all laws and codes, and employ certified or licenced professionals as required by those laws or codes. Hazardous tasks beyond your competence or expertise should also be contracted to professionals. Let's be really careful out there. (c) Copyright 2003 - 2016 Machining and Metalworking at Home The form of the collected work in this text file (including editing, additions, and notes) is copyrighted and this file is not to be reproduced by any means, including electronic, without written permission except for strictly personal use. ============================================================================ Date: Fri, 10 Nov 2000 17:04:53 -0500 From: Jude Miller Subject: Re: New Member Intro > What's the technique and/or required parts to cut metric threads on an > Atlas/ Craftsman? Mine's a Craftsman 12x36. I'm way behind on my e-mail so > if this is answered later on, I'll come to it. If not I'd appreciate help > on cutting metric threads on a cap and ball pistol barrel. Jim Greene There are tables of gear set-ups in "Manual of Lathe Operations". Metric threads rely on combinations involving the 52 and 44 tooth gears. E.g. 1.5 mm pitch uses 44 on the leadscrew meshing with a 52/40 assembly driven by the 16 tooth compound tumbler gear, via an idler. These threads are not exact. They are also not simple ratios of the leadscrew pitch. This means that the threading dial cannot be used. Thus, you cannot disengage the half-nuts until the thread is complete. Instead, after backing out the threading tool, you must reverse the lathe to "unwind" the tool back to the starting position for the next pass. Best, Jude Miller ------- Date: Thu, 16 Nov 2000 13:00:03 -0800 From: "Bob May" Subject: Re: Questions about making a backplate Personally, I would never do any tapping under power with a lathe. It's too easy to miss the stopping of the lathe and run the tap all the way through the work and mess the tap and threads up badly. My method in this case would be to cut the threads most of the way with a cutter and then finish the cutting of the threads with the tap so that most of the metal is already removed and the little bit left will allow for the tap to form the threads properly. For smaller taps into work, I always hand turn the chuck so that I can control the speed and depth of the threading and be able to back the tap out immediately when the tap binds in the hole. Bob May ------- Date: Thu, 16 Nov 2000 15:45:28 -0600 From: "Reger Walters" Subject: Re: Re: Questions about making a backplate A standard thread is based on 75% full thread. The OD of the tap and the Dia of the whole if you use a tap drill chart will give 75% engagement. In hard materials it is common practice to use 60% thread. This can be utilized in soft material also and greatly reduces the forces required. The machinist handbook gives the formulae to figure hole size. There are also tap drill charts available that gives tap drill sizes based on 60% thread. Reger ------- Date: Thu, 16 Nov 2000 22:18:28 EST From: SLEYKINx~xxaol.com Subject: Re: Questions about making a backplate jimirwinx~xxaustin.rr.com writes: > There is certainly nothing intrinsicly "wrong" with using a tap to thread a > hole, if done properly (lots of issues to consider, esp that the hole is > concentric with the spindle centerline). I must say I'm not too crazy about > the idea of using the lathe as an alignment tool and turning the tap in by > hand, however. As soon as the tap starts to bite and pull into the hole (and > away from the tailstock center), you lose alignment and induce wobble > which will distort your thread's concentricity and figure, certainly > at the entrance of the hole at least Jim, That is exactly why I did my tapping in the drillpress. I made a center in the lathe to chuck in the drillpress to locate the center of the tap. (most large taps seem to have a center hole in the square end) I used a bungee cord to hold pressure against the tap so it stayed centered as I threaded it in. This was a first attempt and I was very new to the art but it worked very well for me. Since then I have done quite a bit of single point threading on the lathe, both internal and external. The main thing you need for internal single point threading on the lathe (besides the boring bar and properly ground tool) is a stop of some type so you can see when to di-engage the half nuts. The first few times I used masking tape on the boring bar and found that parralax gave somewhat unsatisfactory results. I finally made a carrige stop that clamps to the bed and is adjustable for a fine stop point. You can watch the gap there and release at a much better repeatability. The other trick is to cut a relief on the bottom of a blind hole or use spacers to set the part to be threaded out from the faceplate. (or chuck) I was not trying to imply that tapping the hole is the best way to go. I only wanted to let folks know I tried it and it works for me ... YMMV. I drew some conclusions from my experiments and basically they came out to show that the thread, when cut first has very little bearing on the accuracy of the finished product. I have a couple of fixtures that thread onto the spindle really sloppy but they run true and repeatable because they 1) seat firmly against the collar on the spindle and 2) the threads are relieved in the last 1/8" or so to fit the unthreaded portion of the spindle. What I see happening is that the threads must either be loose enough or accurate enough to allow the two flat parts to mate properly to eliminate "wobble" and the ID of the last portion of the backplate must be very close to the OD of the spindle next to the collar to maintain concentricity. WAY too much verbosity but that's my 2 cents :) Glenn Neff Medford, OR ------- Date: Wed, 22 Nov 2000 21:42:56 +1000 (EST) From: "Alexander Newman" Subject: At last, I finished something! Well, two things really, but one of them can't function without the other. The first is a tailstock block for dieholders, centres, etc. The second is a tailstock dieholder, with hollow spindle, so that I can pass rod in through the headstock spindle, and out through the spindle, thus allowing me to make long screws. As the tailstock/dieholder assembly has been made so that the centre of the dieholder is at headstock centre height, I can, theoretically at least, cut centered and concentric threads on the same workpiece. This will let me generate an initial leadscrew (for Mr Jeffree's design), and once the leadscrew setup is complete - why, I'll be able to cut a better leadscrew! But first, I have to finish the Jeffree Mk. I dividing head :). Cheers, Alex. ------- From: greg Date: Fri Dec 1, 2000 6:43am Subject: Re:12-20 (Stanley proprietary) thread die >I have access to an engineering lathe etc. that can screw cut this >dimension, but unfortunately I am on the other side of the globe which >does not help most of you. There should be a cheaper solution than the >one offered by Wayne (no offense intended), but I unable to provide it >as yet. Keep looking. You got it! find a neander-galoot with a little time on his hands and do step one then turn the neander-galoot loose on the project. 1. Take a piece of drill stock and thread it ( on that lathe). 2. use a jewelers file to flute it. 3. heat treat the newly made tap. 4. drill a hole in a piece of flat stock. (12" file is good for this size die) 5. use the tap to thread the stock. 6. drill 2 holes that overlap the treaded hole using a die drill, gunsmith drill, or maybe an end mill. 7. heat treat the die. 8. thread a piece of brass. 9. apply grinding compound to the brass and run the die on and off it a few times to clean up any burrs. have a tap make a die. have a die make a tap. it's a chicken and egg kind of thing. The lathe is the answer, make the tap first. greg ------- From: Joe Huld Date: Fri Dec 1, 2000 11:43am Subject: Re: 12-20 (Stanley proprietary) thread die The 12-20 tap is listed in the Rutland Tool & Supply catalog at $9.30. My copy is a couple of years old but I think they probably still have this. (800) 289-4787 for the store nearest you, as I recall their minimum order is $25. This is an imported tool and I suspect the quality is not great but no great precision is required to repair planes. I bought an S.W. Card 'murican made 12-20 tap a couple years ago for a bit less, but it may have been old stock. I think that this size may also still be ordered from Greenfield Tap and Die for something not too outrageous for those who must have the best. Greenfield might also be able to supply cutters for their small size Little Giant adjustable die (their die collets and stocks are terribly expensive new but lots of them show up at flea markets in the common sizes and the stocks collets and guides are interchangeble). ------- Date: Fri, 08 Dec 2000 18:21:55 -0000 From: "George " Subject: Re: Aluminum lubricant "Carl Carlsen" wrote: > A couple of weeks back there was an exchange about threading > aluminum. I was just talking with a long-time machinist, now > retired, who says that, for many years, he has used bees wax, cut > with Turpentine as a threading/tapping lubricant on aluminum. Carl Carl, Bees wax is a great lubricant, we use it in the diecast plant to help loosen parts hung in the dies so we can get the parts out much easer . The stuff is verry verry slick and when melted it is verry thin and will soke into the smallest space! I have never tryed it for cutting threds but if turpentine will disolve it then it should be an exalent thred cutting lube. Tap Magic was mentioned in another reply to your post and is a great taping lube. the best you can buy in my opion! another homemade taping lube. that i have used (power taping 5/8-11& 3/4-10 threds)in the past that would probley work is as followes, take a 16oz bottle fill 2/3of the way with synthedic 5w30 moter oil,add 2 heaping tabel spoons of powdered graphite,finish filling with keraseen. this stuff would make a 3/4-10 tap last for at least 200-300 holes! hope this helps you some George ------- From: Rich D. Date: Mon Mar 20, 2000 11:53am Subject: Re: Thread not deep enough Marc Bernhardt wrote: > Sherliners---Last night I had to cut a 4" long piece of brass rod with > a 3/8"-28 thread. (This strange thread matched a pair of special nuts > in a lighting fixture.) > When I was done the thread meshed beautifully with one nut, but the nut > attached to the ceiling jammed. > Question: How do I remount the rod in the lathe to cut the thread deeper > 1.) without the chuck destroying the threads? and > 2.) getting the 2nd pass thread exactly in the groove of the first pass > thread? Thanks,---Marc Marc, You almost have it right. The thread is the same as 1/8" pipe full diameter straight. That is 27 tpi x .406 diameter with no taper. Lamp threads are very poorly made and very undersized. The several samples in my junk box measure .370 to .390 dia. The idea is to allow easy (sloppy) assembly. Most lathes do not do 27 tpi without special gears. Rich D. ------- From: Date: Mon Mar 20, 2000 1:39pm Subject: Re: Thread not deep enough You can buy a die at a hardware store or at least a tool supply store that is 3/8-28. The lathe has done most of the work for you. Thread the die on the rod and finish the thread., the inital threads from the lathe will keep it aligned properly. If this was an expensive part, it would perhaps be worth the effort to pick up the thread again on the lathe, but this isn't one of them. Picking up the thread again is done by trial and error. You can get very close however. In England, in the early days of WWII, some machinists were still chasing threads by hand without a lead screw! Dick ------- From: Rich D. Date: Mon Mar 20, 2000 7:25pm Subject: Re: Thread not deep enough Marc, I should have mentioned you can buy a die for $11.00 from MSC # 03802022 adjustable 1/8-27 NPS (straight) 800-645-7270. Rich D ------- From: Date: Tue Mar 21, 2000 8:37pm Subject: Re: Thread not deep enough An adjustable die would of course probably fit the bill. What most of us don't realise is that the standard tap/die fit is H3 - 3x0.001 or about 3 thousands loose. You can buy taps and dies that are H2 or even L2 (smaller than). Look, you probably don't want to blow a lot of money on an expensive die right? Use a hacksaw to make an axial cut through one side of a steel nut of the proper thread pitch. Thread it onto the brass rod with cutting oil using a wrench. The jagged edges of the cut in the nut will probably be sufficient to finish your thread. If you were cutting a steel rod, you could case hardened the nut and proceed. We are lucky - we already have a lathe - we can MAKE our own dies and taps. Dick ------- Date: Fri, 12 Jan 2001 01:56:59 -0800 From: "Eric Solberg" Subject: Adjustable Die Holder I have the adjustable tailstock die holder and I was going to use it today to tap a rod using a 1" 1/4-20 die. First, the die holder came from Sherline with the 13/16 bushing in and it was so tight I had to put the holder in the vise and tap it out from the hole in the back. Anyway I then tried to get the die in, and there's no way its going to fit. I tried a little oil and tapping it with the hammer, but it just doesn't go. Is this common, or am I doing something wrong? Thanks, Eric Solberg ------- Date: Fri, 12 Jan 2001 17:34:40 -0000 From: "Rogerio Odriozola" Subject: Screw thread formulas. I thought someone had posted this some time ago but I can't find it on the archive. I need to make a few 8-40 screws and don't know what the thread depth should be. Anyone has this info handy? Thanks! Rogerio ------- Date: Fri, 12 Jan 2001 12:56:31 -0500 From: "Rich D." Subject: Re: Screw thread formulas. Rogerio, the #8 diameter has no effect on the thread depth. It's the same as on a #4 screw. Formula: Single thread depth = pitch x .64952 pitch = 1/TPI No. 8 dia = .164" (major dia) make about .002 undersize for clearance. This is for American National thread form. Put a Machinery's Handbook on your wish list. VERY handy. Rich D. ------- Date: Sat, 13 Jan 2001 23:03:57 -0600 (CST) From: dswrx~xxwebtv.net Subject: All tapped out... This is a question for experienced machinists in our group... First, the sad story.... I wanted to make a threaded collar for my latest project. I carefully chucked a length of 1.125" brass stock. Using a dial indicator, I trued it within 0.001" of being concentric. I faced the free end, and center drilled it. Using the tailstock center to back up the work, I now trued the outside circumference and Knurled it. I drilled the center out with a 3/16" drill followed by a 13/64". I bored the hole to 25/64", the size recommended for a 7/16-20 tap. The collar is 1 1/8" long. I had an old tap with a center hole on it, so I started it the bore using the tailstock to keep the tap straight. After I started the threads, the tap became hard to turn as it was old and worn out. I switched to a new tap to continue the threading. (It had no center hole) To make this LONG story short, the threads are eccentric! (boo-hoo) Can anybody give me clue where I went wrong? (6 hours wasted) Leo ------- Date: Sun, 14 Jan 2001 01:53:54 EST From: catboat15x~xxaol.com Subject: Re: All tapped out... dswrx~xxwebtv.net writes: > I switched to a new tap to continue the threading. (It had no > center hole) To make this LONG story short, the threads are eccentric! > (boo-hoo) Can anybody give me clue where I went wrong? (6 hours wasted) Maybe the new tap did not follow the lead of the old worn tap you started with. Possible cross threaded going into the imperfect threads left by the worn tap. Even if a tap does not have a center for the tail stock you can often use the tail stock chuck to hold the tap straight till you get a good start. John Meacham High Desert of California, Palmdale, Littlerock. ------- Date: Sun, 14 Jan 2001 02:52:21 -0500 From: "Dr. Robert Harms" Subject: Re: All tapped out... I don't rely on the "hole in the end" taps. Get a tap holder with the rod out the back that can be chucked intothe tailstock chuck. This allows you to turn the tap holder and retain the tap perpendicular to the work which is in the lathe chuck. The lathe chuck is rendered immobile via scrap of wood. If you dont have one of these (they are cheap in an import) start the tap by hand by chucking it in a drillpress while holding the work in a vise. After it starts (easy with brass) continue turning the chuck by hand or with a strap wrench. ------- Date: Sun, 14 Jan 2001 02:12:32 -0600 From: Jon Elson Subject: Re: All tapped out... Yes, using a tap where a single point threading tool in a boring bar would make a more accurate thread, at least in terms of straightness and concentricity. One of the tough problems is getting the tap started. If you make the bore undersized or don't have a chamfer to lead the tap in gently, you greatly increase the chances of the tap failing to start at all, thread in crooked or go off center. I rarely use taps or dies on anything important, when I already have the part in the lathe. One trick you can use to get the benefits of both is to cut the threads to about 75% of depth with the threading tool, and finish with a tap. This gets the threads started true, and then gives a thread that is on size and clean. (Sometimes you get rough threads when using single point tools at the low speeds needed for manual engagement and disengagement of the leadscrew.) Jon ------- Date: Sun, 14 Jan 2001 00:11:55 -0800 From: "Eric Solberg" Subject: Help threding steel rod I'm trying to cut a 1/4-20 thread on stainless steel rod, and can't get it to work. I've tried it both in a vise with a wrench, and in the Sherline lathe with the tailstock die holder, turning the lathe by hand. I've also tried a $5 die from the hardware store and a $30 high speed steel die from a tool supplier. I'm using Tap Magic cutting fluid. Anyway, I can't get it to do more than chew up the end of the rod. I tried it on an aluminum rod to make sure I wasn't doing something very basic wrong (I've never done this before), and the aluminum threaded through the die beautifully. Is it possible for me to do this with my setup? Or do I need to have a machine shop do it for me? Would that be expensive (8 rods, about 1" threaded)? These rods are precision ground shafts so I can't just substitute bolts from the hardware store. Thanks for any advice, Eric Solberg ------- Date: Sun, 14 Jan 2001 09:15:20 EST From: aermoterx~xxaol.com Subject: Re: Help threding steel rod I have had to cut the threads on a lathe for stainless steel before. After making a few passes, I could use the die to finish off the job. Tim Christoff Basehor KS. ------- Date: Sun, 14 Jan 2001 12:47:13 -0500 From: "Rich D." Subject: Re: Help threding steel rod Eric, Stainless steel is very tough stuff and comes in several alloys, most of which will resist every attempt to do what you are trying. Which alloy do you have? If you must use stainless for machining, especially on tiny machines, you will need to use alloy #303. (relatively free machining-for stainless). Sounds like you have #304 or worse. Rich D. ------- Date: Sun, 14 Jan 2001 20:30:20 +0000 From: Flosi Gudmunsson Subject: Re: Help threding steel rod Eric, My first attempts at turning with the Sherline was with 303 that I collected from the trash bins where I work. Since then I have tried 304 and 316. The difficult thing when treading this stuff is starting. Put the rod in the lathe and turn small taper on the end. Put the die holder in the head stock and push it firmly against the work while turning the chuck by hand. You may have to use tommy bar in the static part of the chuck. You may have to experiment to see just how firmly you have to push, as soon as the die starts you don't have to push. After the first few turns I usually transfer the work to a bench wise and finish tapping there. You will of course have to use a suitable cutting fluid. Flosi ------- Date: Sun, 14 Jan 2001 12:28:14 -0800 From: "Andrew Werby" Subject: Re: Help threading steel rod I'm trying to cut a 1/4-20 thread on stainless steel rod, and can't get it to work. I've tried it both in a vise with a wrench, and in the Sherline lathe with the tailstock die holder, turning the lathe by hand. I've also tried a $5 die from the hardware store and a $30 high speed steel die from a tool supplier. I'm using Tap Magic cutting fluid. Anyway, I can't get it to do more than chew up the end of the rod. [Try tapering the end of the rod slightly on a grinder- this helps the die get started.] I tried it on an aluminum rod to make sure I wasn't doing something very basic wrong (I've never done this before), and the aluminum threaded through the die beautifully. [Stainless rod is considerably more resistant to machining operations than aluminum. If what you've got is too hard, it may not work with the die you've got. But since you say you've never done this, are you remembering to reverse the direction every half-turn or so? This breaks off the chips that form, clearing the path. While the aluminum may have worked without doing this, the stainless would require it. I don't have my catalogues handy, but you might see if you can find a die with adjustable jaws. I've seen these in pipe sizes- not sure about 1/4-20. They allow you to take progressively deeper cuts until the final thread depth is reached. If all else fails, you might be able to modify your cheap die to cut shallower threads by grinding the back (narrow) threads to more closely match the front (wide) ones (dies are directional- you start at the wide end). Use the modified die first, then follow up with the good one.] ------- Date: Sun, 14 Jan 2001 09:28:23 -0600 From: "J Tiers" Subject: Re: Tapping Thanks Guys... One more thing that I don't think was mentioned. You said you used the recommended size hole. This almost certainly is oversized, for less than 100% threads. That leaves room for the tap to cut eccentric, since it is relying ONLY on the balance of cutting forces to center it. The forces are inherently unbalanced, since the end of the tap is ground to give a start, and the spiral thread naturally has one particular tooth that bites first. So it pretty much HAS to start eccentric. You have to use a single point cutter. But in a 7/16 threaded hole that is not as easy as in a 2" hole. The "micro" boring and threading tools tend to be MUCH more expensive than standard sizes. Your bar would have to fit in about 5/16 to be usable. The dies might or might not be OK. I got New hex dies from Sears that were for new threading (part of a tap and die set). They did not work very well, but they were NOT re-threading types. I did give them back to Sears, because they were off-center, and obviously bad, so they did not give me much trouble about returning them. Lots of folks will hear "hex" and tell you categorically that they are re-threading types, with their ears closed to other possibilities....... It may be that way, but if they are sears, it may not be. I am right now looking at a different set of OLD Sears I got used at an estate sale, and they are hex also, and NOT for re-threading. This set actually works fine, and the price was right. ------- Date: Sun, 14 Jan 2001 15:34:58 -0000 From: "Tim Clarke" Subject: Re: All tapped out... Leo, you didn't say what you used to turn the tap with. A T handle is much eaisier than, say, a 12" crescent wrench. I've used a pair of tee handle tap wrenches that fit taps from 4-40 to 1/2" for a long time now with good results. Both the small, which fits taps 1/4" and smaller and large have a 60 degree center drilled in the offend. This makes it easy to keep everything in line using the tailstock center. Making up a short straight shank center will allow you to use these in your drillpress. I heartily recommend that don't grip a tap shank in any drill chuck. Or at least a good one that you care about. It works well enough, but remember that taps are hardened, and when the shank slips the chuck jaws will wear. Also you'll tighten it up some more and then it'll slip again etc, etc. Remember, drill shanks are not as hard as the cutting end, so they are softer than the chuck jaws. I have a nice 5/8 capacity Jacobs that I had to overhaul, the new jaws weren't cheap. About dies, thread cutting dies come in both round and hex. I have some of both along with rethreading dies. Rethreading dies I have use the same size wrench as the bolt in question does, but the hex dies I have are all 1". Based on my personal experience, I'd say get all round dies for the home shop because it is much easier to make yourself a tailstock die holder for them. It's harder for me to keep a die straight than a tap. Regards, Tim ------- Date: Mon, 15 Jan 2001 11:22:30 -0700 From: lynn.chidesterx~xxxtp.varian.com Subject: Re: All tapped out... One of the ways I've had success using taps in a lathe is to chuck the tap body in the tailstock drill chuck. Then back the tailstock chuck (arbor and tap) out of the tailstock ram, so that the chuck and arbor are free to turn in the tailstock ram, but are supported by the bore of the tailstock ram. Then, by gripping the chuck body with your hand, you can thread the part. This allows you to feel the tapping action. It will also allow you to feel the correct engagement ot the threads (tap/part) when re-entering the part after withdrawing the tap to clean out the chips from the flutes (you did this, didn't you?!) or changing taps. I wonder if the 2nd. tap got cross threaded, or offset (due to chip buildup in the flutes). In either case, I've found that being able to FEEL the cutting action is very helpful. Lynn C. ------- Date: Wed, 17 Jan 2001 13:46:21 -0600 From: Jon Elson Subject: Re: Threading aluminum (HELP) Skip Evans wrote: > I am trying to cut external threads on a piece of round aluminum stock. It > just is not working. Each new cut seems to take with it, the top of the > thread. I have tried heavy cuts (.003-.004) and light cuts(.0005). My > compound is set at 29 degrees and the cutter is 90 degrees to the stock. I > have tried dark threading oil, kerosene, and kerosene oil mix. I have used > a HSS cutter and a carbide insert. I do not know what to try next. Internal > threads cut with a tap are perfect. Some aluminum alloys will not thread worth a darn. if that is your problem, there is not much of a soultion. But, first, you are doing an 8 TPI thread, which requires the side clearance on one side of the tool to be quite extreme. Make sure that side (the left side it would be) is not rubbing against the thread. One easy way to check this is to hold the tool by hand against a completed 8 TPI thread, and see if it touches on the side. Another way is to paint the side of the thread (or tool) with a magic marker and then try a very fine cut, and see if the magic marker is rubbed off. The coarser threads are harder to control at higher spindle speeds, especially when threading up close to a shoulder, but the faster speeds often make better cuts. When using the compound rotated to 29 degrees, make sure the tool is still cutting on both sides. Of course, one side should be making a very shallow cut, but still producing a little shaving of a chip. Otherwise, you will get little ridges down one flank of the thread. You should normally set up so the side of the tool that is taking the bigger cut is facing the chuck. This keeps the carriage loaded against the driving side of the leadscrew, providing smoother motion. If you have been doing it this way, you can try the reverse, but what I described generally gives the best results. Jon ------- Date: Wed, 17 Jan 2001 19:49:43 EST From: SLEYKINx~xxaol.com Subject: Re: Threading aluminum (HELP) One "secret" for internal threading I have discovered is to mark the depth somehow. First thing I used was just masking tape on the boring bar with a mark on it. Since then I have made a carrige stop that I can watch to see when to flip the halfnuts out. I also mounted the compound with the handle to the rear so it feeds in when you turn it in. Real easy to get turned around and feed the wrong way. Go for it! :) Glenn ------- Date: Wed, 17 Jan 2001 20:55:46 -0600 From: "Skip Evans" Subject: Threading aluminum continued I put some brass stock in the lathe tonight for more tests. Here is the procedure I used. 1. Set the compound at 29 degrees 2. set the cross feed against the stock and set the dial to zero. 3. Ensured the tool bit is 90 degreed to the stock and on center. 4. Set lathe speed to lowest with back gear engaged. 5. Took 1st cut at about .003 with the compound. 6. Backed out the cross feed and returned the carriage for another cut. 7. Returned the cross feed to zero. 8. Turned the compound in another .003. 9. Took second cut engaging the half nut at the same position indicated with the threading dial. The second cut did not run in the groove produced by the 1st cut. It ran parallel to the 1st cut a few thousandths ahead of the 1st cut. I have looked for slop and found some in the half nut, if the nut is engaged and my hand removed. So, when I engaged the half nut I maintained pressure on the half nut handle. There is no slop this way. I am at a total loss as to what is wrong. ------- Date: Thu, 18 Jan 2001 02:31:05 EST From: catboat15x~xxaol.com Subject: Re: Threading aluminum continued skip_evansx~xxhotmail.com writes: > I put some brass stock in the lathe tonight for more tests. Here is the > procedure I used. You are not making the mistake I did when I first tried to cut threads I hope. It is so simple I am embaressed to tell of it. What I did was to dis-engage the tumbler gears when I brought the carrage back to the start of the cut. If you this you lose all relationships between the spindle and the lead screw so the second and further cuts never enter the same groove, no matter where the threading dial is reading. Also make sure your threading dial is fully engaged with the lead screw. (Adjust with the square headed bolt, engage the gear and then tighten the screw.) John Meacham High Desert of California, Palmdale, Littlerock ------- Date: Thu, 18 Jan 2001 14:20:02 -0000 From: "Tim Clarke" Subject: Re: Threading aluminum continued HI, Skip, somewhere you have slack in your lathe. A really good place to start would be to check all gib adjustments. Make sure the carriage doesn't twist on the bedways. [rear screws] next, make sure the crosslide and compound are tight. The 2 ends of each gib need to be adjusted properly to keep the twisting motion in check. If you find the crosslide or compound gib pretty loose, better pull the gib out and check it. On my 12x36 they're plastic, and show uneven wear. I haven't done anything about it yet but will soon be making up a new set, probably of brass rather than plastic. I don't have trouble with threads, but get a slight crown when facing. Another thing comes to mind, My 12x36 has a slip clutch for the leadscrew. too little tension there might give you a problem. Directions for adj. are in the book. It should also tell how to adj. the lock for your half-nut latch. I've cut some nice threads with pretty worn half nuts, but they need to lock in the same place every time. Let me know how this works out Regards, Tim ------- Date: Thu, 18 Jan 2001 09:19:39 -0600 From: Jim Irwin Subject: Re: Threading aluminum continued Sounds like your nuts are worn out, Bubba. Hell of a problem for a guy to have! Fortunately not too hard or expensive to fix. You are also using way too slow feed, but that's understandable for trying to see what the heck is going on. Best regards, Jim Irwin ------- Date: Thu, 18 Jan 2001 13:17:45 -0800 From: "Bob May" Subject: Re: Re: Threading aluminum (HELP) When you have the compound rest (dial should be closer to the tailstock than the cutter in angle) set to that 29 deg. and you move the compound in a bit, you should be moving the cutter towards the chuck. This is normal as you are skimming the right side of the groove you are making and cutting into the left side of the groove to make the thread. If you move the cutter in .005" then you should be also going .0024" or so to the left at the same time. This is the way most cut threads - me, I just cut them in and don't worry about the precise angle of the compound rest. I also tend to cut the left/right sides near the top and then fill in the hole further down but then again, I usually don't have a good solid lathe (Unimat) to do things like that well. Bob May My new web space address is http://webu.wigloo.com/bobmay/ or http://nav.to/bobmay ------- Date: Thu, 18 Jan 2001 21:54:59 -0000 From: ikimjingx~xxyahoo.com Subject: Re: Threading aluminum (HELP) "Skip Evans" wrote: > I have the compound turn 29degrees counterclockwise toward the > headstock. I am also engaging the half nut at the same mark. I > did more testing last night and there appears to be some slop > somewhere but I cannot find it. When > making the second cut you > can see that it does not fall into the same groove created by > the 1st cut. It is a few thousandths in front of the 1st cut. I didnt read all posts but you might try leaving half nut engaged and backing out tool then turn chuck backwards {by hand} if a short distance.Go past your starting point so when you start cutting all play is removed.This will eliminate any lead or gear problems.A wore half nut will cut fine as long as it is engaged all the way each pass. Good luck. Jim ------- Date: Thu, 18 Jan 2001 15:05:14 -0800 From: "Dave Engels" Subject: RE: Re: Threading aluminum (HELP) Skip, I've had numerous disasters trying to use the threading dial, and gave up on it. Finally I spent some time looking at the wiring diagram for my motor and realized I can reverse the motor. I agree with Jim, a foolproof way to do it is to leave the half nuts engaged, back the tool out of the thread with the cross slide (carefully noting the depth before you back it out) until it is well clear of the work, then reversing the motor until the tool has backed off to the start of your thread, and then some more. Put the cross slide back to the original setting (being very careful about this), set the compound for the next cutting depth, start the motor in forward to make the next pass at the thread. Be sure to leave enough room to let any play in the lead screw, gears, half nuts, etc be taken up before the tool engages the thread. Good Luck, Dave Engels ------- Date: Thu, 18 Jan 2001 21:14:54 EST From: SLEYKINx~xxaol.com Subject: Re: Threading aluminum (HELP) For a great first go at internal threading you could make an endmill holder. Just get a piece of steel a bit larger dia than the spindle nose, chuck it up bore a blind hole deep enough for the spindle threads and thread it to fit the spindle nicely. Don't take it out of the chuck till you are done fitting it up. Then drill a hole in the side for a spanner and mount it on the spindle. Drill a hole for the size endmill you want to hold, add a set screw and you have a nice endmill holder. Even if you don't have a milling attachment yet :) you can use it to cut slots etc on a block mounted on the compound to make a solid tool holder block. Much more rigid than a lantern and, if you store the appropriate shim with the bit, almost as fast as a QC toolholder. Now .. go make some chips :) Glenn ------- Date: Fri, 19 Jan 2001 21:37:30 -0600 (CST) From: dswrx~xxwebtv.net Subject: nice threads... ... but not the kind you wear! Hey Gang, I just came in from the cold, 8-) and want to crow about the 8 pitch threads I made. (on my Craftsman 6" lathe) They are on a piece of aluminum. I needed a way of mounting my chucks on a rotary table. the thread is 1" x 8 tpi. I followed the Atlas Manual to a "T". I used the slowest speed. 54 rpm, set the tool up with a 60 deg. thread gauge, and advanced the tool with the compound that was set at 29 deg. I did NOT use any cutting oil and the threads came out really good. The book says to feed the compound in 0.108", but I only went in 0.100" and then checked it with a chuck. As it went on easy, I did not go any deeper. One thing I did notice was that just gently turning the chuck up against the shoulder, (the shoulder centers the chuck) it sticks very hard. I guess this is because of the softness of the aluminum and hope it's not because I failed to go the last 0.008"! Tomorrow, I will cut it off and hope (cross my micrometers and hope NOT to cuss) the piece will fit the bore on the table. Leo (the happy threader) ------- Date: Wed, 24 Jan 2001 15:31:59 -0500 From: Reames Subject: Re: Thermos cap So there I was.... Staring at my ancient Aladdin thermos, I'd just busted the cap to smithereens ( dropped it getting out of the truck).... I dislike the pour thru's and only use a solid cheapie plastic cap which is no longer made... Anyway it lay in pieces. and I have an ATLAS!.... I took a piece of 2" delrin, turned it down to size, cut an oring groove, and proceeded to set the QC to 8TPI and throw in the back gears. Cutting the threads, I was dissapointed to see that the threads which were correct, were way way too wide, using the old cap thread depth as a guide. So I made another one, and when I got ready to cut the thread, I used a cutoff tool to cut the threads... perfect, nice wide flats between the threads, and it fit fine.. no leaks. Then for a top cap, I used a piece of round aluminum stock, 2-1/2" dia, knurled 3/8" of it, then bored for a small shoulder I'd put on the delrin end. I faced each flat of the Al using a standard threading tool, pointed directly at the face of the Al, and power cross fed it rapidly to get a nice concentric spiral..... Then drilled and tapped for 6/32 fillister stainless screws to hold the monster together. Looks great, weighs near a pound and is pretty much bulletproof. I figure I can make them for about 50.00 each! I learned a lot cutting those threads with a cutoff tool....and that was the point for me anyway. Probably most of you guys are way beyond thermos caps, but I'm not. Cheers, Mike Reames ------- Date: Mon, 27 Nov 2000 08:51:12 -0500 From: Ronald Thibault Subject: Re: nice threads... >One thing I did notice was that just gently turning the chuck up against >the shoulder, (the shoulder centers the chuck) it sticks very hard. I Leo, If you mean it goes on smoothly and than is tight after it seats on the face of the shoulder, you have it just right! Ron Thibault North Augusta, SC USA Builder Miinie #2 Captain R/C Combat Ship USS Arizona http://pages.prodigy.net/thibaultr/ ------- Date: Sun, 11 Mar 2001 11:17:39 -0800 From: "Marcus & Eva" Subject: Files uploaded to Yahoo groups I have just uploaded a bunch of files to the "files" section. They describe a tiny part that I made a bunch of, last week. They will be of interest to those of you who were talking about workholding, about threadmilling & threadmills, and those of you who have expressed interest in threadcutting on the Sherline lathe in the past. Cheers Marcus ------- [SHERLINE THREADING & SAFETY TIP] Date: Mon, 12 Mar 2001 09:38:58 -0800 From: "Marcus & Eva" Subject: Re: Files uploaded to Yahoo groups The only "GOTCHA" that I can think of is that you have to get used to unplugging the lathe when you want to start threading. (Safety reasons) When you need to switch back to turning, just pull the spindle gear off, and plug in the lathe. That way you don't need to shift the banjo position around all the time. The screw that holds the banjo in position will be a bit of a pain to get to. That's why there's a notch in the bench at the headstock end. Use a Bondhus balldriver, and you should have no trouble. It's ok to leave the handle on at speeds up to about 350 RPM.(but I never do cause I take the spindle gear off..so the handle has to come off too) Beyond that, the unbalanced handle will make the machine start to shake. Cheers Marcus ------- Date: Tue, 20 Mar 2001 00:23:27 -0500 From: Stan Stocker Subject: Re: Re: Taig thread sizes lasernerdx~xxhotmail.com wrote: > My Taig mill uses (as far as I can tell) only 10-32 screws. This is a > very common thead. > For future use, you should have a 1/4-20 tap, 10-32 tap, 8-32 tap and > 6-32 tap. If you're doing really small work, then you get into the 4- > 40 taps and 2-56 taps. Depends on your situation. You should of > course have the tap drills for all these sizes along with the > clearence drills. > If you'll be using a lot of hex socket cap screws, you should also > get the counter bores for the said screws to sink the heads into your > work. Regards, Robin If your interests run to small steam engines you will possibly need 3-48 and 5-40 taps and dies. This is certainly true if you intend to make any of the smaller steam engines from the casting kits from PM Research. Don't buy a hardware store set or the Sears tap and dies sets. Good taps - in the US Brubaker taps are very good for a bit less then Greenfield and darn near as good - cut so much better than the no name ones. The Hanson taps are OK if you need a tap in a hurry. Not Brubaker, Jarvis, or Greenfield, but pretty good taps for the price. I'd add 1/4-28 to the list of must have sizes. In reality, I try to keep at least one of every size NC and NF from #2 to 1/2 inch on hand, and most of the common metric sizes. Bigger and smaller are bought as needed. A 3/4-16 tap is pretty handy as it is the spindle thread size for Taig. Don't overlook that there are taper, plug, and bottoming taps. If you are doing blind holes that must be threaded to within a thread of the bottom of the hole that you need all three, or at least the plug and bottoming taps. As to Dremel - the body nut on the front is 3/4-16. The collet nut is an oddball, measuring the male thread shows a major diameter of 0.278, the best fitting thread gauge (inch or metric) is 40TPI. The major diameter is also 7.0mm. None of my metric thread gauges matched up perfectly though, although an .60 came closest. There is no 7-0.6 metric thread in Machinery's Handbook, nor is there are 9/32-40. No taps in this size showed up in Rutland or in the Enco catalog. Externals could be single pointed in a screwcutting lathe or perhaps using a Frog on the Taig. Looks like Dremel didn't want to make it easy on others to make attachments to their little motor! Stan ------- Date: Tue, 20 Mar 2001 16:18:42 -0000 From: ballendox~xxyahoo.com Subject: Dremel threads was Re: Taig thread sizes Stan, Good advice. You may not know that newer Dremel "mount" threads are 3/4-12. The older ones are 3/4-16, as you stated. Also the newer dremels "stick out more" from these threads than the older ones did... (means the collet and tool tip are farther away from the mount threads' point of view). Hope this helps. Ballendo ------- Date: Wed, 21 Mar 2001 05:58:09 -0000 From: ballendox~xxyahoo.com Subject: taps was Re: Taig thread sizes [ROLL TAPS] > Never heard of the ROLL type before, will they just work in > relatively soft alloys ? Rab Not just soft, but malleable. Includes steel, some stainless types, brass, some bronzes, and aluminum. Not cast iron! (too brittle) Don't really know about malleable CI, tho... You all DEFINITELY want to look into this. It's real, it works (I was a skeptic, and stayed with cutting taps longer than I should have... Like I mentioned, Balax is one Mfr. (They have a good technical rep) Hope this helps. Ballendo P.S. Roll threads are stronger, TOO! Kinda like forging on a small circular, helical scale :-) ------- Date: Wed, 21 Mar 2001 10:58:42 -0000 From: ballendox~xxyahoo.com Subject: taps was Re: Taig thread sizes Thanks, Nick: I forgot to mention that the roll taps are stronger, since there is no need for "chip clearance" (the body is "fuller") While I'm here, there IS one down side to these taps. If you're running them in a tapping head, it is harder to tell when they are "dull" (they don't really GET dull, since they don't start out "sharp", but they do wear out, and get harder to turn. Also possibly falling out of tolerance in forming the threads, but a thread checker (plug gage) will keep you aware of this... So just be sure to run a screw periodically through your tapped holes to check that the threads are still being FULLY formed... Hope this helps. Ballendo ------- Date: Thu, 22 Mar 2001 13:54:16 -0700 From: "Les Grenz" Subject: Re: taps was Re: Taig thread sizes >> "It was easy once I made the tap and die." Did you make a conventional tap? Any words of advice for how to make a tap without running into the problems Joules mentioned? I've been intrigued with the idea of making taps and dies, but without the ability to cut single-point threads on my lathe (yet... I'm planning on getting a Frog as soon as I have cash-flow again) it just hasn't been an issue. But the idea of making thread-forming taps is intriguing, like Joules said. Thanks, Tom << Hi Tom, I have made special taps and dies. I did, however, cut the threads on a Sherline lathe and a Maximat 7. After the threading I made a quick and dirty tap by grinding only one flat flute. This was good enough for making a die. Not pretty but gets the job done. Some of the 0-80, 00-90 taps are made with three flat sides rather than flutes. Brass and plastic are all they are really good for. Regards from Les Grenz & the Queen City of the Rockies. AWI 18150 NAWCC 82932 some tips --> Tip #1 - Threading Music Wire. We are often asked can you thread music wire. The simple answer is NO. We tell folks if you can file it, you can thread it. The hard music wire will quickly dull a set of dies. The exception is if the end of the wire is "annealed". The annealing requires that the wire be heated to a cherry red and then allowed to air cool. In doing this the temper or hardnes is removed from the spring music wire. A normal Benzine torch is adequate to heat the wire of either 1/8" or 3/32" size. In most cases you will want to control how far up the wire the annealing will travel. After all for some reason we want the spring properties of the wire to remain. To accomplish this a "heat sink" is needed to isolate the annealing heat to the area of interest. The heat sink can take any form but it must be heat conductive, fairly large in mass, and be in tight contact with the wire. A large bench vise works well. I have used a coffee can full of wet sand. In some cases a large pair of vice grips will work. No matter which sink is used, place the wire so that just the end to be annealed is sticking out of the heat sink. Apply the torch until the area is glowing red hot. Then remove the heat and allow the wire to cool completely. At this point the area that was heated should now be soft enough to thread, but the wire in and beyond the heat sink will still retain the original spring properties. I hope this helps. Tip #2 - Differential Screws Here is a technique you might want to try. In the June 1998 issue of Model Airplane News there was an article "How to Mount Wings Using Differential Screws" by Al Ehrenfels. The basic principle is that if you put two different thread pitches on the end of a rod you can create a "turnbuckle" effect even though both threads are right handed. I would encourage you to read this article. Here is how RODCHUCK can be used. Since a commercial 4-40 rod is a "rolled thread" the actual rod is 3/32" in diameter. This means that an end of the rod without threads can be threaded with our 2-56 die set. If you do this then you will have a 4-40 thread on one end and a 2-56 thread on the other. Standard screw on clevises can be used to terminate the rod ends. To use the rod, first screw the 2-56 clevis in as far as practical. Then just start the 4-40 clevis on the rod. Anchor the 2-56 and 4-40 clevises to their attachment points. Then as you screw the rod "into" the 4-40 clevis it will "unscrew" from the 2-56 end. However since the pitch is different (56 threads per inch Vs 40) the rod will unscrew 1/56inch per turn and screw in 1/40th inch per turn. The distance will become shorter between the two clevises by 0.007" per turn. With commercial rods I found that approximately an 1/8 inch of adjustment can be achieved (18 turns). I plan to use this technique on my next giant scale that needs tail brace wires. But I am sure there are other applications for the technique. By the way don't forget a "jam nut" on one end to keep the rod from backing out and loosening once the vibration starts. ------- Date: Sun, 13 May 2001 00:10:15 -0500 From: "Dana Zimmerman" Subject: [ACTUALLY ABOUT A Q ON METRIC THREADING] The important gears for metric operation in the 6" atlas are 52-tooth and 44-tooth. These have the ratio or .846154 which is very close to 1/30 of 25.4, the ratio of inches to millimeters. 44/52=0.8461 25.4/30=0.8466 difference = .00051 The difference is small enough to neglect, especially for lens adapter threads which are usually only ten or less threads engagement. Also see about the file chang8.zip at the files are of the atlas_craftsman group here: http://groups.yahoo.com/group/atlas_craftsman/files/gears/ This is a program that can calculate gear choices for thread pitches you require, using the gears you have on hand. ------- From: "robert B" Date: Tue Jul 10, 2001 2:09 pm Subject: cuttintg inside threads ? I have an Atlas 12x36, with what I think is a compete set of attachments. Among those is a tool holder which is supposed to hold a round "L" shaped bar, which is ground at one end to cut inside threads. At least that is what it shows in my Atlas handbook. My problem is, I cant seem to find this threading bar in my box of attachments, and I need to cut some inside threads. ... From 4140 steel. Does anyone know where can I get one of these inside threading bars? Is there any alternate available? Could I braze a piece of carbide to a steel bar and grind it to a thread shape myself? Could I maybe braze a piece of HSS to a boring bar then grind it to shape ? Then cut threads with that.. Or..will the welder's heat that ruin the temper of the HSS ? Any suggestions on how I can cut some inside threads ? Thanks Bob ------- From: dswrx~xxw... Date: Tue Jul 10, 2001 5:30 pm Subject: Re: [atlas_craftsman] cutting inside threads ? If you can't find one to purchase, you should make your own.... Depending on the size of the bore that you want to thread... Purchase a piece of drill rod (not cold rolled steel) that is smaller than the i.d. of the bore.... Bend the end to form a right angle, making sure it will still enter the bore.... File the bent end to the proper shape for the threads you want to cut... Don't forget to allow adequate front clearance.... Heat the bent end to a bright cherry red, hold at that color only for a few seconds... Plunge into water to harden.... Check the hardness, using a file... The file should skid across the bent end, leaving no mark... Polish the bent end to a shiny steel color... Hold piece in sunlight (to see colors, not for temperature) and heat slowly with flame away from bent end about an inch... Watch the colors as they move to the bent end and quench in water as soon as a light straw color touches the tip of the bent end... Touch up the point with your grinder or stone and you have your threading boring bar... Lots of fun, if you don't burn your fingers! 8-) Leo (yes, i've made one, but not for threading) BTW: Remember, when you are boring with a long bar suspended only at one end, it will deflect (spring) away from the work! Take very light cuts, several with no feed as you approach the final size. ------- From: "Ebower" Date: Tue Jul 10, 2001 8:14 pm Subject: Re: [atlas_craftsman] cutting inside threads ? If You are going to harden in water be sure to purchase water hardening drill rod (W-1). If you purchase oil hardening (0-1) you can use motor oil. (If using motor oil be sure there is no gas in it. Especially if you use old motor oil). I buy a quart or two of cheap motor oil for this purpose only. Earl ------- From: catboat15x~xxa... Date: Wed Jul 11, 2001 12:23 am Subject: Re: [atlas_craftsman] cutting inside threads ? dswrx~xxw... writes: > : Remember, when you are boring with a long bar suspended only at one > end, it will deflect (spring) away from the work! Take very light cuts, > several with no feed as you approach the final size. You are right, and a long boring bar made as you described is likeIy to chatter badly. I have wraped wire solder around a boring bar to eliminate this chatter, Old timers trick, don't know exactly why it works, but it often does. ------- From: JMartin957x~xxa... Date: Wed Jul 11, 2001 1:24 am Subject: Re: [atlas_craftsman] cuttintg inside threads ? Best way I've found is to use a boring bar with replaceable cutters. Easy to make one yourself - or several, for different size bores. Make bar out of round CRS or drill rod. Drill a hole through the side of the bar, near the end, to take a cutter. Hole can be at 90 degrees or at 60 degrees. No reason not to use both ends of the bar..... Drill and tap a hole in the end of the bar for a setscrew to hold the cutter in place. Cutter can be round (old broken taps work well) or square if you want to file the hole out to a square. I like round, as you can rotate the cutter for different clearance angles. While rotating the cutter, and rotating the bar to bring the cutter exactly on center height, will change the included angle a bit, you probably won't notice. Armstrong holders in a lantern toolpost are what probably came with your lathe, but you'll probably find a homemade toolblock or boring bar type toolpost to be much more rigid. Pretty easy to make. Internal threading takes a bit more planning and concentration than external. You'll need a runout groove which you can't see, need to get the clearance angles and compound angles in the right directions, and have to remember which way you'll be moving the crossslide when you disengage the halfnuts. Sort of like driving on the left side of the road after you learned on the right. John Martin ------- From: Robert McDonald Date: Wed Jul 11, 2001 7:41 am Subject: Re: [atlas_craftsman] cutting inside threads ? At 12:23 AM 07/11/01 EDT, catboat15x~xxa... wrote: > ..... I have wrapped wire solder around a boring bar to eliminate >this chatter, Old timers trick, don't know exactly why it works, but it >often does. John Meacham The added weight would change the resonant frequency of the tool/bar/post assembly. That probably helps reduce the vibration at a given speed. Rob ------- From: dswrx~xxw... Date: Wed Jul 11, 2001 8:15 am Subject: Re: [atlas_craftsman] cutting inside threads ? That sounds about right, Rob. Just as a bell will not ring properly when you put your hand on it, the solder "dampens" the natural resonant frequency of the bar. I have not cut internal threads on my lathe as I am too clumsy to handle all the things you have to watch! I would "spazz" out as my grandchildren used to say! Leo (thank the iron god for threading taps) ------- From: sleykinx~xxa... Date: Thu Jul 12, 2001 1:21 am Subject: Re: [atlas_craftsman] cuttintg inside threads ? If you have "extra" standard boring bars of the "L" shaped type you can grind the thread form on one of those and use it just fine. I have done that. I have also taken a carbide boring bar of the cheap chineesey variety and ground a threadform on that and used it with success. My favorite, however, is the 1/2" storebought bar that has the square holes for a lathe bit. I got some carbide blanks that fit and those are great but HSS seems to work just a bit better at the slow speeds needed for threading. Couple of "lessons learned"; If you have room for a groove at the bottom of the threads for "escape," use one. Mark the boring bar with masking tape to give a depth of thread so you can release the halfnuts at the right spot. Better yet make or otherwise aquire a carrige stop and set that up to give a visual depth of bore. I use a feeler gauge with one hand between the stop and the carriage to get a good feel for when to disengage the feed. This mode does not work with no escape groove or for metric/odd threads where you can't disengage the halfnuts. For those situations a battery and a light with a spring loaded switch on the stop works to give you the right timing to stop the lathe and reverse the feed to back out for the next run. FWIW Glenn ------- From: "robert B" Date: Thu Jul 12, 2001 3:06 pm Subject: More inside threads I have just cut an outside thread. It is 3/4" reverse, fine thread. I must now make a nut to fit this thread. It is to be 3/4" reverse fine. From 4140 cold rolled steel... When I did set up the lathe the last time, for the previous outside reverse thread, I just set the compound at 29 deg,(but with the crank handle toward the headstock) and threaded from the head stock end toward the tail stock. It worked fine. I got a good reverse thread. Now I must cut the dammed nut! And I can't for the life of me figure out how to set up the machine. And the manual is vague on this. What I need to know is: For a reverse inside thread... Should the compound's crank handle point toward the headstock, or toward the tailstock when I set it for the 29 deg? In Which direction should the lead screw drive the cut? Toward the head stock, or toward the compound? Assuming a reverse inside thread.... ------- From: ikimjingx~xxy... Date: Thu Jul 12, 2001 6:06 pm Subject: Re: More inside threads In atlas >To cut left hand internal threads you can have compound crank facing as you normally would to cut right hand external threads but run lathe in reverse and cut on the back side of the nut with the tool upside down. This way you can see each cut start into part and your compound will be putting cutting pressure towards the direction of feed. Hope this makes sense. ------- From: Jon Elson Date: Thu Jul 12, 2001 11:03 pm Subject: Re: [atlas_craftsman] More inside threads robert B wrote: > I have just cut an outside thread. It is 3/4" reverse, fine thread. > I must now make a nut to fit this thread. It is to be 3/4" reverse fine. > >From 4140 cold rolled steel... > When I did set up the lathe the last time, for the previous outside reverse > thread, I just set the compound at 29 deg,(but with the crank handle toward > the headstock) and threaded from the head stock end toward the tail stock. > It worked fine. I got a good reverse thread. > Now I must cut the dammed nut ! And I can't for the life of me figure out > how to set up the machine. And the manual is vague on this. > What I need to know is: For a reverse inside thread... > Should the compound's crank handle point toward the headstock, or toward > the tailstock when I set it for the 29 deg ? It really doesn't matter! It just determines which side of the thread will have the big chip, and which will have the thin one. > In Which direction should the lead screw drive the cut ? Toward the head > stock, or toward the compound ? > Assuming a reverse inside thread.... This is determined by the cutting tool. If the cutting tool has a flat top (like a normal lathe tool) then the work must come down onto the tool (like normal turning). If the tool points to the front of the lathe, then you must cut this thread toward the headstock for a RIGHT HAND thread, and toward the tailstock for a LEFT HAND thread, which I assume is what you are doing here. (If the tool points toward the back of the lathe, spindle rotation is backwards (CW as viewed from tailstock) and the above directions would be reverse. Obviously, with the work rotating down on the tool, the tool HAS to follow the thread in the work. Imagine the work already has the thread in it, imagine the lathe turning, watch the imaginary thread and see which way the thread seems to "walk". If you run the carriage the wrong way, you'd get a right hand thread instead of left. Jon ------- From: sleykinx~xxa... Date: Sun Jul 15, 2001 12:41 pm Subject: Re: [atlas_craftsman] Internal threading springx~xxm... writes: > The internal threading "thread" has been very interesting, as I am > pondering making a tail stock ram threaded 1/2 - 20 for my AA109 to > enable using the half inch chuck that came with the lathe for > drilling. The inside thread on the original ram is 5/16 - 24 left > hand. I have been looking for left hand tread taps in this size, but > haven't found anyone that sells them. Any one have any ideas? > Cutting this small thread on the lathe will require a small bar. Any > ideas on how to handle the small stuff? (I haven't tried inside > threading yet) The HSM way would be to make a tap on the lathe and use that for threading on the smaller strange threads. LH taps are available but :) I would go with adapting the chuck to your existing ram though in this case. There are adapters available or you can turn one on your lathe as previously described. One note.. when you use the tailstock setover method you must turn between centers not the chuck and tailstock. Regards Glenn Neff Medford, OR ------- From: hdetwilersx~xxa... Date: Mon Jul 16, 2001 9:09 pm Subject: Re: [atlas_craftsman] Internal threading Best source of boring bar that small are good quality Allen wrenches. The hold up well and grind easy. Don't be afraid to grind your own tool. Just use the clearances listed in any book on lathes; keep the tool cool while grinding, and finish off by using a stone. Just jump in and do it -- you can't go too far wrong. Use a dial indicator on a magnet to tell when you have hit the end of your run and you are in business. harry ------- From: nathanandannax~xxc... Date: Sun Aug 12, 2001 10:39 pm Subject: varying thread pitch Has anyone experienced variations in thread pitch whe using an Atlas 10inch? I have cut threads before on South Bends but this is the first time I have tried it onmy Atlas. I have it geared up correctly but every other thread looks thicker. I checked TIR before I started and it was just shy of .002. Is this small amount enough to cause my problem? I am taking very small cuts so I don't think it is deflection. It is also a 1 3/8-16 so it should be solid. Any help would be greatly appreciated. Nathan ------- From: Jon Elson Date: Mon Aug 13, 2001 1:03 am Subject: Re: [atlas_craftsman] varying thread pitch nathanandannax~xxc... wrote: > Has anyone experienced variations in thread pitch whe using an Atlas > 10inch? [SNIP] Any help would be greatly appreciated. Off-center work won't cause threads to be varying in thickness along the length. It will cause the threads to be thicker on one side, and thinner on the other. Is there any possibility you have made a double-start thread? If you just started scratching the surface, you could get a double start which would look like a 32 TPI thread at first glance. You can't engage the leadscrew at any position it will engage at on the coarser threads. The 10 and 12" lathes use an 8 TPI leadscrew, so any tooth on the leadscrew is OK - IF you really are set for 16 TPI. The most obvious test is that the leadscrew should turn exactly one full revolution when the spindle turns exactly 2 full revolutions. (For 16 TPI, 2 turns = 1/8 In) If the leadscrew doesn't turn exactly 1 turn for 2 turns of the chuck, then your gearing is not right. If the thread is slightly different from 16 TPI, then it would be easy to get a double start, even with a threading dial. Since you've never threaded with this lathe before, it is quite possible that one of the spindle gears is not the correct number of teeth (should be a 16 and a 32) or that some other wierdness has been done to the lathe. make sure the leadscrew is really an 8 TPI, too. Jon ------- From: Date: Tue Aug 14, 2001 1:18 am Subject: Re: [atlas_craftsman] varying thread pitch Is it possible that the leadscrew is not rotating true? If the engagement with the halfnuts varies regularly, and you are cutting a thread that is a multiple of the lead pitch, then you could have a problem of a non-constant advance. This would be due to the nuts engaging more deeply and then less deeply into the leadscrew, so that the leadscrew does not correctly position the saddle. If the leadscrew is bent, that can happen. It does not have to be very much of a bend, and it may look like it is straightened out as it goes thru the apron workings, but the effect may be there. The atlas does not guide the leadscrew as positively as some other machines with more complex apron workings. If you are cutting 16 tpi, then the 8 tpi leadscrew could cause a variation in every other thread groove, as you say you see. Jerry ------- From: dswrx~xxw... Date: Mon Aug 13, 2001 5:41 pm Subject: Re: [atlas_craftsman] varying thread pitch Make sure the bearings that support the lead screw are bolted down solidly. (especially the left-hand one) I was making a cut on my 6" lathe and was surprised to see the carriage travel stop and start again, all by itself! Trouble: the screws had loosened on the leadscrew bearings! Hope this helps, Leo ------- From: Robert McDonald Date: Tue Aug 14, 2001 2:11 pm Subject: Re: [atlas_craftsman] varying thread pitch At 04:41 PM 08/13/01 -0500, you wrote: >Make sure the bearings that support the lead screw are bolted down >solidly. (especially the left-hand one) I don't remember what kind of lathe the original poster has, but my 10" doesn't have a left-hand bearing on the leadscrew. The left end of the leadscrew rides in the output gear in the QC gearbox. Rob ------- Date: Mon, 20 Aug 2001 18:11:38 From: "robert B" Subject: Re: Thread questions >From: HUNLEY31x~xxaol.com >Reply-To: atlas_craftsmanx~xxyahoogroups.com >To: atlas_craftsmanx~xxyahoogroups.com >Subject: [atlas_craftsman] Thread questions >Date: Mon, 20 Aug 2001 10:55:01 EDT >Well, as I continue to practice and experiment with my lathe more questions >keep coming to mind. Hope that I'm not making a pest of myself. Now the >problem, Lets say that I'm making a "threaded plug" to fit into a block of >steel. What size hole do I drill in the material if the "plug/bolt" is to >be about 1"? What size shaft do I start with before I cut threads on the >plug part? Where did you find the answer? And lastly is there a "rule of >thumb" about diameter-radius threads per inch? A standard so to speak, >like 1" 10TPI, or !/2" 18TPI. Think NASDAQ will ever comeback? Thanks in >advance. Hank Well, first off... For a 1" hole, you look up in , say, "the machinests ready reference" to find out which size bit you need that is going to be the diameter of the root of the thread, then you tap it larger to the thread size. About # threads per inch. Go get a standard thread bolt at the hardware store, and count them. This will tell you how many threads you need. And it will give a good idea of what the threads should look like. Remember there are fine and course threads. They have a different # threads per inch. Or you can get a thread pitch gauge, and fit the little blades into the threads until you find the one which fits, ,, that is # threads per inch. Fine or course, two sizes. For outside thread, turn your stock to the full diam. IE 1". As for how to set up the lathe: Set lathe in back gear. Adjust compound to 29 deg. align threading tool to level with the work, and stright on. move compound, and crossfeed forward to touch the work. set both to zero. lock in place the thread counter. start the lathe, and when any counter line matches up to the main marker, make a passing cut of about .oo1 . Is all looking right ? good. Return to the starting point. When the thread counter lines match up,(this tells you that you are starting at the same spot each time)... advance the ....COMPOUND .002 , and make your first cut, don't forget to use cutting oil, or lube oil. At the end of your cut, stop the saddle. rotate the ... CROSSFEED .. out one full 100. return THE SADDLE to the starting position. rotate the .. CROSSFEED .. forward the full 100 The reason for this is to consistantly allow the cutter to clear the work when returning to the starting position after each pass. OK, now advance the COMPOUND forward by another .002 When the thread counter shows you are at the proper position, make your next pass. Keep this up till you are done. How to tell when you are done: a friend of mine finds the bottom of his threads by painting the stock with dye kem, then when the blue dissappears , he knows that the threads are done. OK, now about the threaded plug you mentioned. Is this thing a tapered pipe thread? To cut a tapered pipe thread...Well I have never done this before, so can't advise. I suspect that you must off set the tail stock. Oops! forgot something. You need a hog wallow where your threads will finish. This is a grouve, where the cutter can land as it finishes each pass. You'll figure this out after the first threading attempt. Clear as a bell hummm...? Bob ------- Date: Mon, 20 Aug 2001 15:34:31 EDT From: catboat15x~xxaol.com Subject: Re: Thread questions HUNLEY31x~xxaol.com writes: > Lets say that I'm making a "threaded plug" to fit into a block of steel. > What size hole do I drill in the material if the "plug/bolt" is to be > about 1"? What size shaft do I start with before I cut threads on the plug > part? Where did you find the answer? And lastly is there a "rule of thumb" > about diameter-radius threads per inch? A standard so to speak, like 1" Hi Hank: I am still waiting for DOS to come back, don't know about NASDAQ. But for your other questions the answer is fairly easy. There are books, tables etc that give the information on hole size for a particular thread and national standards on TPI as prefered sizes. There is a coarse series and a fine series for threads for each diameter. I use a shirt pocket book printed by GW Morse, Cutting tools Division. I don't kow if it still available but I think other people put out the same information. The master book and guide is the Machinists Handbook (expensive) But my little booklet gives drill sizes for all COMMON threads and for the percent of thread a given drill size will produce. You don't need 100 percent thread, most times 50 to 75 percent will save taps and do the job. Various standard making organizations such a SAE (Society of Automotive Engineers) make standards and have these standards published as ANSI (American National Standards Institute) As an example under the table for 1/4 inch it shows two standard threads, one 20 TPI and one 28 TPI (coarse thread and fine thread) and gives drill sizes for everything from 100 percent down to 50 percent. For a 1/4 by 20 I generally use a number 6 drill which gives me about 75 percent thread. Of course you could thread a 1/4 inch bolt at 47 threads per inch, but it would not be a standard thread and a tap may not be available. These are the threads normally seen in machine work, automotive, aircraft etc and taps and dies are offf the shelf items. Now to complicate things there is the ME standard series (Model Engineer) which needs special ME series taps and dies. Optical standard threads (the really fine threads used on microscopes and telescopes) Pipe threads which are tapered. Almost any tool supplier can give you a chart with similar infornation. When you make a plug to fit a hole the convention is to turn the plug to the nominal size, then to cut standard threads for that size drill or bore your hole according to the chart. If you are getting into precision work there are tables for the tolerances by class of fit. I think there are formulas for calculating all this stuff, but the tables are sure handy to have on hand. While you are pondering all this think about in machine threads the larger numbers are larger screws, but the drills you use to make the hole you want to tap the larger numbers are smaller diameter drills. No one promised you that this hobby would make sense, but it's fun anyway. John Meacham High Desert of California, Palmdale, Littlerock. ------- Date: Tue, 21 Aug 2001 22:50:00 -0500 From: "Dana Zimmerman" Subject: RE: Re: Atlas Gears For Atlas-Craftsman Lathes the 52 tooth and 44 tooth gears are the ones for metric thread cutting. The theory behind this is that 44/52 = .846154 x 3 = 2.53845 which is close enough to 2.54 for engineering purposes. (Unless you are making micrometer screws...) And yes, I (and Atlas) do know that 44/52 is _really_ = 0.846153846153846153846153846153846... as your Windows Calculator will tell you. Exact metric pitches would require a 50-127 gear pair or the like. For 24dp Atlas 618 (6") gears this would include a 5 1/2 inch dia. gear (approx.) probably too big for the harp. I don't know about the 12" lathe. ------- Date: Thu, 18 Oct 2001 00:17:32 EDT From: sleykinx~xxaol.com Subject: Re: A question on dies. HUNLEY31x~xxaol.com writes: > I'm in the market for a set of tap and dies. I've noticed that some dies > are "split" so a minor adjustment can be made. Is this a feature worth > considering? Any suggestion on what brand or considerations? Thanks Hank The split dies allow you to adjust for fit ... if you want a tight thread you widen the split. Handy many times when you are matching up old threads or need a nut to stay put. You can thread the full length with the die split and then drop it down and go back over the starting part and get a thread that starts easy and tightens up where it counts. My personal preference is Greenfield .. they seem to last forever. A good mid line set is from Hanson .. they work well but aren't quite as good or expensive as the Greenfields. One other approach for home shop use is to get a "good" set from Harbor Freight and then replace the most used ones as needed. They will serve fairly well for occasonal use and it gives you a complete set for 1/3 the cost. I have a metric set from HF and so far have not had any trouble. The only complaint is they don't run quite as nicely as the Greenfield or Hanson sets. There really is a big difference in feel. The threads all seem to come out about the same though. Regards Glenn Neff Medford, OR ------- Date: Wed, 19 Sep 2001 08:29:17 -0700 From: "Craig Libuse" Subject: Re: Re: Threading Bits [ON SHERLINE LATHE] >Can the thread cutting attachment 3100 cut internal thread? George, Yes. The thread cutting attachment simply gears the spindle to the leadscrew in the proper relationship to both rotate the part to be threaded and move the cutting tool in the proper relationship. It doesn't care if the thread being cut is internal or external. That's just a matter of how you set up your cutting tool. By the way, there is a picture of an inside threading tool and a standard threading tool on page 164 of Joe Martin's book, "Tabletop Machining". It is in the chapter on cutting threads. To read the instructions on how to use the Sherline thread cutting attachment, see www.sherline.com/3100inst.htm or www.sherline.com/3100inst.pdf. Craig Libuse Sherline Products ------- Date: Wed, 19 Sep 2001 20:04:51 -0000 From: paul_probusx~xxyahoo.com Subject: Re: Threading Bits > I am working on plastic with lathe. I am planning to get a thread cutting > attachment 3100 kit. If I buy this kit, can we make a thread same as 2 > litre pop bottle's cap thread (both internal and external)? Reid I just happen to be drinking a 20 oz. soda which has the same thread as the 1 and 2 liter bottles. It looks to be an 8 tpi pitch (I measured the threads on the bottle I have) with an Acme type thread form (may not be an actual Acme but it looks close). The attachment should be capable of producing this thread. Checking Sherline's site shows the kit will thread as course as 5 tpi. Since 8 tpi is a fairly common course thread so I am sure that the attachment would be able to cut this thread. It does have a good span to cover just about all the common thread pitches the hobby machinist would need. As far as external and internal threading, Craig Libuse (sp? sorry if its spelled wrong) said it best when he said that the threading attachment is used exactly the same way for external threading and internal threading. There are some differences between making an internal and an external thread, but those differences have nothing to do with the threading attachment itself or its use. Those differences lie in the type of tool used (a boring tool for internal threading, turning tool for external, the form of the tool for each is the same, ie. 60 degree threading or 29 degree Acme), type of setup (just about have to cut internal threads in a chuck of some kind or mounted onto the faceplate, external threads can be cut with the part "chucked" to the lathe in any fashion, even between centers) and the advancement of the cutter into the material may be different (normally during internal threading the tool is advanced in the direction of the operator although the tool could be mounted upside down and advanced away from the operator, external threading could be done either way also, although it is normally done by advancing the tool away from the operator). If you are unfamiliar with threading and do not have any books on the subject, I recommend you check out Lindsay Publications, they are online at: http://www.lindsaybks.com. I recommend Colvin's book, "Running an Engine Lathe". The books goes into pretty good depth about cutting threads with change gears. Two other good books, South Bend's "How to Run a Lathe" and Sheldon's "The Care and Operation of a Lathe". I bought all three. They cover the same material, just from a different viewpoint. At a minimum, I recommend Colvin's book and one of the others. I do not have any ties to Lindsay Pubs. except that I am generally a satisfied customer(a couple books I have bought are worthless for practical material, but I do not blame that on Lindsay). Paul ------- Date: Wed, 19 Sep 2001 14:32:19 -0700 From: "Craig Libuse" Subject: Re: Threading Bits > I am working on plastic with lathe. I am planning to get a thread cutting > attachment 3100 kit. If I buy this kit, can we make a thread same as 2 > litter pop bottle's cap thread (both internal and external)? Reid, If the threads are indeed 8 TPI as one of the other forum members measured, the 3100 attachment can cut them. Keep in mind that threads with a pitch of 9 TPI or less have an interference problem between the handwheel and the 40-tooth gear. There is a note about this in the instructions. This is fixed by making a small spacer to separate the handwheel from the gear on the spindle, moving the handwheel further out on the shaft to keep it from hitting the 40-tooth gear. Originally the threading attachment was not designed to cut threads this coarse; however, after many requests from woodworkers, Joe worked out gear ratios to cut threads down to 5 TPI. If you cutting in plastic, the deeper cuts required on this size thread should be no problem, although you still may want to cut them in several progressive passes. You will have to grind a pair of special threading tools (Internal and external) to match the shape of the soft drink bottle threads. It will probably take some trial and error to get a good fit, but it sounds very doable. I don't know your application, but if it's just a prototype would it be practical on the internal threads to bore a hole the size of a metal or plastic pop bottle cap in your piece and press, glue or screw it in place? If that is strong enough and it doesn't show, it would be a lot easier, although not nearly as elegant (or strong) as cutting your own custom internal threads. Craig Libuse Sherline Products Inc. ------- Date: Mon, 31 Dec 2001 02:02:59 EST From: catboat15x~xxaol.com Subject: Re: threading questions .. again Rswart1x~xxtwcny.rr.com writes: > plus .. is a there any reason why you might want the > bit a little above or below center when cutting threads ?? Stay right on center, above or below will foul up the geometry of the thread. Don't tell a soul that I said this, but a three cornered file has 60 degree angles at each corner and when no one is looking will sure clean up a ragged thread. John Meacham California High Desert 12 inch Atlas, Minimill, rusty file ------- Date: Mon, 31 Dec 2001 23:51:01 EST From: catboat15x~xxaol.com Subject: Re: threading questions .. again cbrumbelowx~xxhome.com writes: > Does one do this with the thread spinning, John? Thanks, Charles yes, with the work spinning at about the same speed as when cutting the thread. Just watch out that the end of the file does not catch on a chuck jaw or something and get the tang pushed into your hand, That hurts bad! Use files with handles. It should be just a clean up of burrs left after thread is cut. I have also single cut threads then run the proper size die down to clean up any burrs. John Meacham High Desert of California, Palmdale, Littlerock. ------- Date: Mon, 04 Feb 2002 11:19:28 -0800 From: Dave Martindale Subject: lathe threading I've already had several requests for my threading spreadsheet, so I uploaded it to the "files" section for the Sherline list on the Yahoogroups web site. Just look for "/metal/lathe_threading.xls". When you open it, you'll see 6 tabs across the bottom for 6 worksheets. The first two are for the Chinese 7x10 lathes and any larger lathe with an 8 TPI leadscrew, the last four are for the Sherline and mostly duplicate Sherline's own threading gear tables. The sheet labelled "Sherline II" is for an Imperial (inch) dimensioned Sherline cutting Imperial threads, "Sherline IM" is for an Imperial lathe cutting metric threads, and so on. Although the tables just list what data Sherline provides, the right-hand "TPI" and "pitch" columns are calculated. You can make the tables longer (use "fill down" in Excel) and then type your own gear tooth counts in the ABCD columns, and see what the resulting TPI or pitch would be. And if you look at individual calculated cells, you can see the formulas in them. It should be pretty easy to build new formulas for non-standard gear setups. Note that it can't tell you what gears to use to get a particular TPI or pitch - it can only tell you what TPI/pitch you'll get from a selection of gears that you've made. Dave ------- Date: Wed, 13 Feb 2002 23:00:19 -0800 From: "todd smith" Subject: Re: Re: Tapping Titanium! In sherlinex~xxy..., "todds670" wrote: > Good evening to all. I need some tips on tapping grade 5 Titanium. It > seems to go well for awhile, but after 3 or 4 parts, SNAP!! And there > is another wasted part.I was thinking of going to the next size drill > bit, but was wondering if the threads would be tight enough. Any tips > or suggestions would be of great help. Thanks for your time, Smitty >>From: terry6453 Sent: Wednesday, February 13, 2002 8:49 AM To: sherlinex~xxyahoogroups.com Subject: [sherline] Re: Tapping Titanium! Hi Smitty, Titanium likes to smear on the tap surfaces and stick to it. After a point, it can suddenly "weld" the tap in place. Lots of sulfer cutting fluid and keeping the tap clean is supposed to work at preventing the seezing. Replacing the taps often is also recommended. The titanium nitride coated taps may help too if sticking is the issue. Larger hole sizes may be fine if the taped hole still has enough strength, which it should in Ti. Cheers, Terry << Terry, thanks for the help. Got a new tap today, got 10 parts done and still have the tap in one piece!, I will try a larger bit and see if my struggle continues, Thanks again, Smitty ------- Date: Sat, 20 Apr 2002 23:12:14 -0400 From: "Daniel Munoz" Subject: hexagon dies vs. round dies. I need to use a specific die for a single job, 5 mm x 0.5 metric. The catalog where I usually buy stuff like that only have High speed die for this size, not ordinary carbon die. For half its price I could buy a carbon die, but the hexagonal kind, used for rethreading if I'm not mistaken. Do you think I could use a rethreading die to create a thread in aluminium? I noticed that carbon rethreading dies are always less expensive than carbon round dies. What is the reason? Could rethreading type be used with some care to create threads, especially in soft material, aluminium or brass? Thanks a lot for your advice, Daniel. ------- Date: Sun, 21 Apr 2002 16:47:30 -0700 From: "Nicholas Carter and Felice Luftschein" Subject: Re: hexagon dies vs. round dies. You will be happier with split dies, but a rethreading die will work in a pinch. It is best to reduce the diameter of the work a bit, if you can. Which catalogs are you looking at? See our web pages http://www.cartertools.com/nfhome.html ------- Date: Sun, 21 Apr 2002 20:29:19 -0400 From: "Daniel Munoz" Subject: RE: hexagon dies vs. round dies. I was looking the KBCTOOLS catalog http://www.kbctools.com They deliver locally both in US and Canada, and I have other things to buy there so it is convenient. I need a die metric 5 x 0.5 for a single job, and adapter for a friend's aerograph. So I was searching for the minimum price to pay, because I have no other need of this die :-) I have a full box of various taps and dies, but no 5 x 0.5 unfortunately. The HSS metric 5x0.5 die is 11.73 $CAN at KBCTOOLS, the hexagonal die is 5.59 $CAN. Not a big deal, after all it's only a few $, but my question was also to understand if it could be possible to use those cheap dies in aluminium and still have a proper result. Daniel. ------- Date: Wed, 24 Apr 2002 12:41:49 -0700 From: "Marcus & Eva" Subject: Re: Re: Tips Hi Craig: I had a look at the link you posted. She looks just grand to me. I'm not concerned in the least about where credit goes...so long as it works well for people. I've been using the Sherline lathe this way for a few years and I've advocated this way whenever someone has complained about the inconvenience of having to remove the motor when threadcutting. If you wish, I can knock up a quick drawing of the extension, but it's a pretty simple project. If anyone is wondering what the rigamajig on the carriage is for; I used to turn a lot of really tiny threads in titanium alloy. I've found that milling them is far better than trying to single point turn them. The gadget is a 34,000 RPM Foredom spindle mounted to the carriage with a homemade bracket. It's driven by a standard Foredom flexible shaft and motor. I've got a 1/4" diameter, 2 flute carbide threadmill in the collet. I can cut an M2 x 0.4 thread in a single pass, and I don't need a thread runout groove at the left hand end. This makes the thread much stronger. I developed the method for making custom components for dental implants. It is ideal for modellers who need to cut very small, fine-pitch threads when the length to diameter ratio exceeds 1.5. Cutting the thread in one pass allows you to retain the maximum strength in the blank for as long as possible. It's kind of like Joe Martin's method of cutting thinwall tubes that he describes in "Tabletop Machining". Hardest part is coming up with the cutter. I cheat: I've got a homemade cutter grinder to do the job. Cheers Marcus ------- Date: Wed, 24 Apr 2002 15:51:39 -0400 From: "Dan Statman" Subject: Re: Re: Tips Marcus, I have a thread cutting question for you in reference to this post that you made. I need to make an axle for a titanium yo-yo that somebody has commissioned for me to design and make. I have a 3-mm ID bearing that will be used for the string to ride on, and the two halves of the yo-yo will thread onto an axle that fits inside the bearing. I plan to use a 4-40 stainless threaded rod (a cutoff machine screw), and then make a tube that just fits the inside bearing diameter and is also threaded 4-40 to fit the axle through. Would you be willing to make me a single piece with a center section that is 3-mm long and 3-mm OD with a 4-40 thread on both ends? I am not sure how long the threaded ends will need to be, but I think about 5-mm on each end will work. I would like to get it made out of 6/4 titanium alloy. This would be a more elegant solution to my axle needs (and it would eliminate any stainless steel from the design), but I do not have the ability to do this in a reasonable amount of time. What are your thoughts, and what would you charge me. I can supply the piece of 6/4 titanium if you do not have any in the right size. Let me know and thank you. Also, if anybody else would like to tackle this axle for me, let me know. Thanks, Daniel J. Statman, Statman Designs www.statmandesigns.com ------- Date: Wed, 24 Apr 2002 17:31:05 -0400 From: "Carol & Jerry Jankura" Subject: Re: Re: Tips Marcus: Can you expound a little more about exactly what you're doing. Is the idea that, instead of mounting a thread cutting tool, you mount a burr that grinds the thread as you move the spindle/carriage? Jerry ------- Date: Wed, 24 Apr 2002 19:16:54 -0700 From: "Marcus & Eva" Subject: Re: Re: Threadmilling in the lathe Hi Jerry: That is exactly what I do. The "bur" that you are referring to is a 2 flute threadmill. If you've never seen one, it is shaped like a tiny saw with 60 degree vee shaped teeth. I grind mine out of solid carbide round stock. They do a beautiful job and leave a super clean thread. There are still some pictures in the "files" section of the Sherline group. http://groups.yahoo.com/group/sherline/files/Cutter%20Grinding%20101/cutter% 20collection1-9x12.jpg Here's the link; the cutter second from the left is a threadmill for cutting a mold cavity that had buttress threads in the slides. It was milled into hardened stainless steel at 52 Rockwell and worked beautifully. (Didn't do that in the Sherline though...this cutter has a 1/2" shank, and was used to mill a thread 2 1/4" diameter.) The cutter on the far right is more typical of what gets used in the Sherline. (It happens to be a tee slot cutter, but the principle's exactly the same.) Cheers Marcus ------- Date: Wed, 24 Apr 2002 20:00:05 -0700 From: "Marcus & Eva" Subject: Re: Re: The Great Yo Yo Caper Hi Dan: I can make your part, no problem. I've got lots of Ti6Al4V alloy in 3mm and 4mm diameters. I'm a bit concerned however, that the mass of the Yo-Yo will twist the axle off at the thread. 4:40 is only 0.110" dia at the thread crest and about 0.085" at the root. That's pretty skinny to handle the kinds of forces that a spinning Yo Yo can generate. The big problem will be when the Yo Yo accelerates and decelerates at the end of its cycle. You'll either spin the hubs off the axle, or snap the thread, I fear. If I was going to make this part, I'd plan on an axle at least 1/4" diameter. I'd probably make it out of hardened steel and put a shallow taper on each end. Then I'd tap the ends 8:32 and thread in a blind stud from each end. I'd turn accurate tapered pockets into the cheeks and drill & tap the ends 8: 32 as well. Then I'd slip a 5/16" Oilite bushing over the hardened pin, Loctite the tapered sockets and assemble the whole works. Biggest trick would be to keep from Loctiting the bushing to the shaft. Best way I can think of is to run a very skinny bead of soft wax across the joint and onto the end faces of the bushing. The advantage of the method I describe is that the thread is protected from assuming the strain. The coned sockets function like Morse taper sockets, and will give even better performance than squaring the end of the shaft and broaching the cheeks. It also avoids having the screws showing from the outside. If you are really desperate to use the bearing, another way is to turn the shaft as part of one cheek. Put the tapered socket only on the one side and make the thread as part of the shaft (which is, of course, part of the other cheek). With a coned socket to protect the thread, you just might get away with it. Make sure you put the biggest fillet you can get away with at the junction of the shaft and the first cheek. Let me know what you think. Cheers Marcus ------- Date: Thu, 25 Apr 2002 06:04:17 -0400 From: "Dan Statman" Subject: Re: Re: The Great Yo Yo Caper There will be no problem with the halves spinning apart on the shaft as there will be no forces that are on one side and not on the other. This is a common design for high-performance yo-yos. In addition, the gap spacing between the two halves is what controls the ability to retrieve the yo-yo from the down position. As the string is slackened the friction from the side walls will tend to coil it around the axle. This distance is set to the tenth of a millimeter using replaceable spacers. Different users want (and require) different spacing in order to work the thing properly. It is absolutely mandatory that the two halves be easily taken apart and spacers added and removed from the axle. The yo-yo will be quite light as a lot of the excess titanium is removed from the body. There will be some perimeter weighting used by keeping about 50% of the total mass within 15% of the outside edge of each half. It should spin at several thousand RPM and will sleep for over 3.5 minutes and still be retrievable. How long would it take to create the titanium axle as described in my first e-mail? Thanks for all of the help. Daniel J. Statman, Statman Designs www.statmandesigns.com ------- Date: Thu, 25 Apr 2002 18:08:09 -0700 From: "David Goodfellow" Subject: Re: Re: The Great Yo Yo Caper This thread reminds me of the story of the Haikuku Maru, carrying a cargo of Taiwanese yoyos, went down in a storm -- 17 times. Dave Goodfellow Northridge, CA ------- Date: Thu, 2 May 2002 21:09:46 -0400 From: "Dan Statman" Subject: Re: Re: The Great Yo Yo Caper Marcus, All I can say is: AWESOME!!! You are a very talented machinist. You have created a piece that I had no chance of making, and it looks and works beautifully. I am in your debt. I have finished roughing out the two halves and have tried them and they work very nicely. I will be adding quite a few artistic components to the final design, but wanted to make sure it worked properly first. For those that do not know what I am making, it is a titanium yo-yo. Marcus was kind enough to create an axle from grade-5 titanium with a center section 3 mm long with a 3 mm O.D. and ends that are 5 mm long each with a 4-40 thread. He made it slightly oversized on the O.D. of the center section so that I could bring it down to a press fit with emery cloth. I do not have the proper tuning spacers for the axle bearing to set the proper gap between the halves, but I can get the yo-yo to sleep for over 60 seconds and still return up the string. Thanks again, Marcus! Daniel J. Statman, Statman Designs www.statmandesigns.com ------- Date: Thu, 18 Jul 2002 18:30:07 -0700 From: Robert Bond Subject: Cutting threads in Aluminum I've been trying to cut decent threads in some aluminum parts with my 6" Atlas lathe. So far cutting at 100 sfpm with feeds of about .008 per pass gives the best results. I've been feeding the tool into the part at about 29 degrees. The tool is sharp and I've adjusted the gibs as well as I can. I've been using "LPS Tapmatic #1 Gold" cutting fluid. Anyone have other recipes that work? The Machinery's Handbook feeds and speeds are much too high for my lathe. The parts are made of 6061 aluminum. Bob ------- Date: Thu, 18 Jul 2002 23:18:51 -0500 From: Jon Elson Subject: Re: Re: Cutting threads in Aluminum Single point threading of aluminum is always a bit marginal. The problem is that 100 SFPM is just too slow for aluminum. but, unless you are doing extremely fine threads, the carriage ends up moving too fast for manual engaging / disengaging of the halfnuts. Coarse threads require some tricks to prevent the flank of the tool from dragging on the left side of the thread. Cut the threads at the highest possible speed that you can safely disengage the nut. Some people have a trick to alternately cut on opposite sides of the thread, by alternately advancing the infeed and the compound. This sometimes helps with ragged threads. Jon ------- Date: Fri, 19 Jul 2002 10:09:53 -0700 From: "Bob May" Subject: Re: Cutting threads in Aluminum Fiddle with the cutter's position. Chippy cuts tend to be from too much rake on the tool and the job with making threads is worse than most cutting as you are working both sides of a pointed cutter in the cut so it's going to want to grab more than normal. One way is to work only one side of the cut at a time by working the cutter back and forth a few thou (depending upon the thread size) to relieve the cutter so it cuts only one side. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Fri, 19 Jul 2002 10:47:09 -0700 From: Robert Bond Subject: Re: Cutting threads in Aluminum I've been using the Atlas lantern tool post. The way I bring the tool up to center is to rotate it back. Would it be better to shim it up so that the tool is more horizontal rather than tipped up? That would reduce the rake, right? By running the tool in at 29-30 degrees I'm mostly cutting the front side of the thread. I'll try moving it around a bit, see what that does. Bob ------- Date: Fri, 19 Jul 2002 12:03:10 -0700 From: John Weight Subject: Re: Cutting threads in Aluminum Another way is to set the tool as usual ( with the compound set to 29 degrees,) and advance the tool using the compound so that the tool is only cutting on the leading edge of the tool. This makes for better material flow off the tool face........then advance the tool in using the cross feed for the last few thou. to clean up the form and leave a better finish. JohnWeight, San Francisco ------ Date: Fri, 19 Jul 2002 21:31:36 +0200 From: "j.c.gerber" Subject: Re: Cutting threads in Aluminum Bob, I fully agree with you. I do not know the aluminum 6061 but the 6060 and the 6082. They are not the best alloys for cutting threads and their Mn content is high (0.5-1%) wich makes it somehow brittle for threads. Setting the upper carriage to 29 deg and cutting paths of 0.005" using the cross slide to go reverse to take a new path with the upper slide gave me the best results. HSS cutters are better than HM for that purpose. Recently I was in a hurry, tried to "quickly" make an adapter out of alu 6082 with an HM tip for fitting a hand pump on small oil drums and took paths of 0.002. What a result!! A catastrophy. Jean-Claude, Switzerland www.homestead.com/turnandmill ------- Date: Fri, 19 Jul 2002 20:41:03 -0400 From: "Paul & Charlene Wilson" Subject: Re: Cutting threads in Aluminum TapMatic also makes a formula specifically for aluminum; makes a lot of difference. It is alcohol based as opposed to oily .... Paul ------- Date: Sat, 20 Jul 2002 10:18:50 -0700 From: "Bob May" Subject: Re: Cutting threads in Aluminum What you really want to do is to make the tool perpendicular to the work rather than to the center here. The problem is that if the tool's top surface isn't at the height of the center, your cutting angle will be off as the important thing is to have the angles at the working surface correct, not the cutter "level" (there's that word again after the long lathe leveling thread!) to the work. Chatter tends to come from too much relief and a top surface too much at an angle so it is trying to cut like a knife blade rather than scraping the material off. What is also making the chatter worse is that the width of the cut that you are doing as you get towards the bottom of the cut - you are trying to get both sides of the cut at one time which is also making things even more worse as the cutter will also be pushed to the side and thus deeper into the other side you are cutting - all making cutting threads one of the harder chores to do properly without chattering. You have to run the aluminum version of the Tapmatic fluid instead of the other metals version because the standard stuff WILL combine with the aluminum and produce a interesting pale violet fire in the aluminum. I've done it and found it rather disconcerting to see happen, especially when the job is almost done. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Sat, 20 Jul 2002 17:14:07 -0700 From: Robert Bond Subject: Re: Cutting threads in Aluminum "Perpendicular" is more what I intended than "level", thanks. I tried both a HSS and a carbide thread cutting tool and had more luck with the HSS tool. It may be because the angle was wrong - the carbide tool is not as thick as the HSS tool so it was tipped up more in my toolpost. It had a tendency to skin off the threads half-way through. As I posted earlier, I got a new quick change toolpost but I have not yet had a chance to try threading with it. It will be easier to set perpendicular. As far as cutting fluid goes, the "#1 Gold" Tapmatic fluid actually works pretty well. It's meant mainly for non-ferrous metal though they say you can use it on steel. I broke several taps (by hand) before I got it - haven't broken any since. Bob ------- Date: Tue, 23 Jul 2002 21:53:30 -0700 From: "Marcus & Eva" Subject: Re: Re: Tap wrench for mill ----- Original Message ----- From: "Alan Marconett KM6VV" To: Sent: Tuesday, July 23, 2002 1:42 PM Subject: [sherline] Re: Tap wrench for mill > Hi Mike, > With a taper tap, the tap gets quite a way into the hole, and you can > run the Z down until the tap's threads just start to engage the hole. > Don't use the draw bar (I have a chuck with the M1 taper from my EMCO 5" > lathe without a draw bar that I've used in the Sherline mill for MANY > years), use just enough friction to keep the chuck from falling out of > the spindle. > > After a turn or two into the work, the taper will start to "walk out" of > the spindle, and then a little less "alignment" will be provided by the > mill. It'll still keep the tap lined up (perpendicular) as you go > further down. > > After 3 or 4 turns in, I often drive the Z up and out of the way. Then > I have a little more room, as the tap is already properly started. The > little drill chucks make excellent small tap holders, I find that I can > hand tap often much easier with them then with a tap wrench! If you > need a little more torque, then leave the chuck key in the chuck, or use > a tommy bar, to help it. You want to get the "feel" for the cutting of > the tap (don't forget the tapping fluid), and this way (without a BIG > tap wrench) you'll know when it starts to bind up a little and it's time > to back it out. > > Ron's "Precision Drilling" attachment, as I mentioned, can provide > additional "guidance" for the tap, as it can follow (guide) the tap down > even further. I haven't tried one yet. Alan KM6VV Why not just turn up a short 3/8" dia shaft and thread the end to fit your drill chuck? You can then slide it up into the 3/8 endmill holder and run it up and down with complete confidence that it will stay aligned enough for any tapping job. By the way, if you need anything more than easy hand pressure on anything smaller than a 1/4:20 tap, your hole's too small or your tap is hooped. (this is assuming you've got it chucked in a Sherline 3/8" drill chuck.) Toss them out when they start to cut hard...it's not worth having to scrap out a block because you snapped off the tap. Cheers Marcus ------- Date: Wed, 24 Jul 2002 08:31:23 -0400 From: "Carol & Jerry Jankura" Subject: RE: Re: Tap wrench for mill If you look in the files area, you'll find some pictures of a quill for the Sherline mill made by Ron Ginger. The URL is: http://groups.yahoo.com/group/sherline/files/Sensitive%20Drilling%20Attachme nt/ It's a little fancier than Marcus' recommendation, but is a little more versatile. If you're not into building one, you might also try Sherline's "sensitive drilling attachment." Jerry ------- Date: Wed, 16 Oct 2002 22:14:08 -0700 From: "Orrin B. Iseminger" Subject: Re: repair of threads in bolt hole Well, there are a number of options: 1) Drill for the next size larger thread size, and thread it for a larger screw, bolt, etc. 2) Drill (or bore) for a couple sizes larger thread, thread it, and cut a tight fitting male plug. Loctite the plug in place. Then, drill and tap the plug for the original sized thread. 3) Use a standard thread repair insert, available at auto parts houses, etc. This would be the expensive way to go because I think you'll need a specialized tap and installation tool. 4) Bore out the damaged thread and chamfer each end of the hole. Turn an aluminum plug to fit the hole, but make it a bit longer than the thickness of the piece. Loctite the plug in place and before the Loctite has set up, upset (mushroom, like a rivet) each end of the plug to fill the chamfer. Face off the excess material on each side, drill and tap for the original sized thread. There are bound to be more ways, but I've used all of the above, except #3, with success. Orrin ------- Date: Thu, 17 Oct 2002 01:21:56 -0500 From: "Al Lenz" Subject: RE: repair of threads in bolt hole Devin, first, using the correct tap, clean up the existing threads and using a mirror, magnification or whatever is required, inspect the damage. Sometimes only the first thread or two is really bad. Then lots of questions. How many good threads will still be engaged? Is the fastener in tension or shear? If there is at least one full diameter or more of good thread engagement, then you should be OK as is. Assuming that is not the case, then go get an insert. Heli-coil is a good standard. It will require a special tap and may come with an insertion tool, but if not, the tool is trivial to make. This will put you back as good as new, (no that is not true, you will be BETTER than new, i.e., steel threads in soft al.) This is not very expensive and is very straightforward. Good luck, al ------- Date: Tue, 21 Jan 2003 15:58:16 -0600 From: Greg Gelhar Subject: Metric threads I would like to cut some M12 x 1.75 threads. The manual with my 6" Atlas shows some metric threads but not 1.75 pitch. I know I can figure this out, but if I don't have to reinvent the wheel, I won't. Does anyone know the change gear set up for 1.75? Also, if it is not to much trouble, could we all include where we are when signing off? It would add even more interest to these postings. Greg Gelhar Osseo, MN ------- Date: Wed, 22 Jan 2003 05:56:19 -0000 From: "anthrhodes " Subject: Re: Metric threads > anyone know the change gear set up for 1.75? Try: 32 Tumbler Gear | 52-48 | 56-64 | 36---16 TPI Leadscrew = .06878" or 1.7471 mm. I don't know if this will set. If necessary you can always add an idler but it's more likely you might run into not enough room. The above sequence looked the most likely but you can place any driver in any driving position and any driven in any driven position. The drivers are 32, 52, and 64. The driven are 48, 56, and 36. This was arrived at by modifying the change gear setup for the 12" lathe. Since the 6" leadscrew is half the pitch of the 12" leadscrew the gearing doesn't require as much reduction, in fact it's a slight step up. Hope this works for you. Anthony ------- Date: Sun, 26 Jan 2003 09:22:15 -0500 From: "Jason Richards" Subject: Newbie Q- Threading to a Shoulder Hello all- got a newbie question that I haven't been able to figure out on my sherline or my 8" Logan- How do I go about threading to a shoulder? I need threads closer to the face than I can get with a full 60 degree tool- On smaller threads I can work a die to the shoulder and then reverse it, and complete the threads, but on larger threads I can't (or won't buy a die for) how do I go about this? Thanks- jason ------- Date: Sun, 26 Jan 2003 21:20:25 -0600 From: "Scott Peterson" Subject: Re: Newbie Q- Threading to a Shoulder Hi Jason, I've seen folks create a narrow, often radiused, relief cut just a shade deeper that the minor diameter of the thread next to the shoulder. This allows room for the tool, or a die. Radiusing the cut greatly reduces chance of stress cracks. My two cents... Scott ------- Date: Mon, 27 Jan 2003 02:18:28 -0600 From: "Gordon Couger" Subject: Re: Newbie Q- Threading to a Shoulder Grind the tool so it will cut right up to a shoulder. Just visualize a threading tool with the tip offset to one side of the tool and bent a little. Gordon Couger Stillwater, OK www.couger.com/gcouger ------- Date: Wed, 05 Feb 2003 03:21:13 -0000 From: "Thomas E. Jones " Subject: Re: Sensitive Drilling Attachment "kentfreeman " wrote: > I was thinking (dangerous) of buying the Sherline sensitive drilling > attachment and using it to hold the taps. I would drive the tap with > the the handel from the threading attachment on an extension. > I was thinking that this would be a nice hand tapping machine for > small taps such as #4's and 6's. What do you think? I've thought of the same thing, and previously I think posted if anyone else tried it. I got the sensitive drilling attachment, and realized it could hold a tap, so why not use the whole mill as a hand-tapping machine? It can be done, but isn't terribly convenient. The sensitive drilling attachment doesn't allow much "torque" for tapping, and is made for low-torque drilling. Secondly, the drill chuck is 3-jaw, so the square head of a tap doesn't fit well. However, if a normal "T-Handle" tapping tool can just be supported near the spindle, allowing the tap handle to be used for torque, and the spindle just lining up the tap with the hole, that will work. Try drilling a 1/8" hole through the middle of your T-Handle tap, then put a 1/8" Rod in the tap-wrench hole you made. Then you chuck up the rod, and the tap-wrench is just supported axially over the hole you want to tap. The hole through the tap-wrench doesn't have to be deep, maybe just 1/2 to start the tap, because once the tap starts, it's easier to keep perpendicular. The above being said, I mostly tap by hand, usually 2-56 to 0-80 holes, and find I can line things up best myself. Of course, I buy the taps cheaply, so if they break, I'm not out of production. tj. ------- Date: Fri, 21 Feb 2003 20:20:16 -0600 From: Ronald R Brandenburg Subject: Re: Re: what is a full set of gears? Original Message ----- From: "Dr. Robert Harms" To: Sent: Friday, February 21, 2003 7:13 PM >I cannot speak to Atlases but I do not think they differ from my SB in this regard : when you use the metric conversion gears (SB called them metric transposing), the tread gauge doesn't apply and you cannot open and reclose the half nuts based on the thread gauge and have to reverse and restart each cut. < If I had a full set of gears, would I be a machinist? Ron... ~ Always remember: Hard work pays off in the future, laziness pays off now. ------- Date: Sat, 22 Feb 2003 14:52:40 EST From: anthrhodesx~xxaol.com Subject: Metric Conversion (Was Re: what is a full set of gears?) In a message dated Fri, 21 Feb 2003 19:23:52 EST, Doc writes: << i have some calculations w/ 56/44( in stndrd loose change set),that are off in vicinity of .11% -.05 %,& u can do better yet w/ 47/37 >> The standard Atlas set-up was 44/52 whic gives an error of approximately 1/4 of that given by 56/44. The 47/37 set-up is used by Logan and gives approximately 1/3 the error of 44.52 but does require *special* gears. << anybody ever cut a 127 gear & attempt to use it on a loose change atlas /crftsm or 10 in Logan ??? enuf clearance??? >> I expect it would be a problem as the 127 is twice the size of the largest standard gear, but there is a work around. In Martin Cleeve's book on screwcutting he mentions making special 127 and 40 tooth gears at 30 DP for his Myford. The standard Myford gears are 20 DP so the 127 was slightly larger than the largest standard gear, 80 tooth 20 DP. In this set-up he always used the 40 to drive the 127 so they were the only odd gears and this prevented a mismatch from trying to mesh 30 DP gears with 20 DP gears. The point here is that you don't have to stay with the original configuration, it's your machine, you can adapt it an any way that solves your problems. Anthony Berkeley, Calif. ------- Date: Sat, 22 Feb 2003 15:04:41 EST From: anthrhodesx~xxaol.com Subject: Metric Conversion (Was Re: what is a full set of gears?) Dr. Robert Harms writes: << I cannot speak to Atlases but I do not think they differ from my SB in this regard : when you use the metric conversion gears (SB called them metric transposing), the tread gauge doesnt apply and you cannot open and reclose the half nuts based on the thread gauge and have to reverse and restart each cut. >> This is a universal problem and applies to any screwcutting done in a different measuring system (ie metric) than that of the leadscrew (ie inch). There are designs where you leave the half nuts closed but reverse the leadscrew gearing to return for the next pass. But the Tumble Reverse mechanism doesn't allow this, it requires leaving the gear train and half nuts always engaged and stopping the spindle, reversing the spindle either by motor or hand crank, and restarting the spindle in forward. If you're interested in the kinds of reversing mechanisms which allow reversing of the gear train without stopping the spindle and still maintaining the correct relationship for cross-system screwcutting, read Martin Cleeve's book and/or study the reversing mechanisms used by Hardinge, Monarch, Rivett, Pratt & Whitney, Hendey, and some others. Anthony Berkeley, Calif. ------- Date: Sat, 22 Feb 2003 17:08:21 EST From: n8as1x~xxaol.com Subject: Re: Metric Conversion (Was Re: what is a full set of gears?) anthrhodesx~xxaol.com writes: > The point here is that you don't have to stay with the original > configuration, it's your machine, you can adapt it an any way that solves > your problems. anthony .....tnx for the idea of 30 pitch final gears .....now have some more calcs to occupy my failing mind while waiting for the ground to dry out for spring plowing.....think it may work better w/ a quick change box off hand as cud then keep same pair (drivers are variable w/ loose change)..........since 127 gear works best on screw,maybe an auxilliary hanger is answer to allow o/size gears ........... regarding atlas .....looking in atlas manual at loose change metrics , it appears only a few set ups use 44/52 .......i checked one of the other setups, & was surprised how far off they considered acceptable ........just a mental exercise anyway(get thee behind me ,altzheimer), ..........it is easier for me to cut metrics on my loose change 1895 Reed 14 in.,since the feeds are by separate fixed cone belt drive ,thereby making threading changes MUCH simpler ( one or 2 gears ),since the compound set up feeds are not comingled ......which was a real pleasant surprise....as was the elevating crossfeed ,allowing instant cranking the tool bit to center ,or for allowing abt 1 in vertical travel for milling setups!......some of the ancient stuff has merit.....also surprised that ridgidity not affected........took an easy .300off diam........at .400 the worn canvas belt wanted to slip ( gravity tensioned belt..need to get a decent belt & set up positive belt tension ) .....again its academic as i rarely have a need to take off more than 1/8 in /pass.....reckon id get a gear head if i was in a hurry........tnx for opening the box i was trapped in, for more possibilities best wishes docn8as ------- Date: Sun, 23 Feb 2003 16:51:35 +0000 From: "brianx~xxsquibb.org.uk" Subject: Re: Metric Conversion (Was Re: what is a full set of gears?) At 09:38 23/02/2003 -0600, you wrote: > > I would have no option but to do it this way as I have a gearbox which > > makes it very difficult to strip it down to change gears. >Seems there should be a train of accessible change gears that run the >gearbox.................maybe you don't have them? This is assuming you >are using an Atlas, or why are you here? The homemade gearbox is bolted to the left hand end of the lathe. To change the change gears I would have to take the gearbox off. It does mean that all my gears are straight cut steel:)) I will get a more detailed picture and post it - here is the best I have at the moment. http://www.squibb.org.uk/lathe/headstock.jpg Brian ------- Date: Sun, 23 Feb 2003 18:39:15 EST From: anthrhodesx~xxaol.com Subject: Re: Metric Conversion (Was Re: what is a full set of gears?) In a message dated Sat, 22 Feb 2003 17:08:21 EST, docn8as writes: << tnx for the idea of 30 pitch final gears .....now have some more calcs to occupy my failing mind while waiting for the ground to dry out for spring plowing.....think it may work better w/ a quick change box off hand as cud then keep same pair (drivers are variable w/ loose change)..........since 127 gear works best on screw,maybe an auxilliary hanger is answer to allow o/size gears ........... >> Cleeve was using this on a change gear Myford although the idea could be adapted to a QC setup. Let me give you a clue how this would work (my examples, not Cleeves). On the Myford, if you geared 1:1 you would cut the same pitch as the leadscrew which is 8 TPI, let's say 40 stud gear drives any idler drives 40 screw gear. If you wanted 16 TPI you might setup 20 stud drives any idler drives 40 screw, 1:2 reduction gives half the leadscrew pitch or twice the leadscrew TPI. For metric, if you were to put a 40 tooth 20 DP gear on the stud driving a 40 tooth 20 DP gear on the change gear stud, then mount the 40 tooth 30 DP gear parallel on the change gear stud and have it drive the 127 tooth 30 DP gear on the leadscrew you would get a 1:1 ratio through the 20 DP gears compounded by a 40:127 ratio through the 30 DP gears. The resulting pitch would be 1 mm. To prove this mathematically you can ignore the 20 DP gears in this example since they provided a 1:1 ratio or no change, therefore (40 30 DP / 127 30 DP) x .125" pitch gives .039370078" pitch which, when multiplied by 25.4 to convert to mm = 1 mm. To get different metric pitches change the ratio of the 20 DP gears. So 20 driving 40 in 20 DP gears compounde by 40 driving 127 in 30 DP gears gives (20 x 40) / 40 * 127) times .125" pitch = .5 mm. Essentially, the 40/127 ratio converts the .125" leadscrew pitch to 1 mm pitch. Being interested in this concept for my own purposes, my inclination is to add 80 and 120 tooth 30 DP gears to the set which, when used as drivers with the 127 tooth 30 DP gear, would give an apparent leadscrew conversion to 2 mm and 3 mm respectively. 100/127 would convert the .125" pitch to 2.5 mm. The above examples were all associated with the Myford standard of 20 DP change gears. For the Atlas you could still use the 30 DP conversion gears but you might want to use 24 DP instead. The largest standard gear in the Atlas set is 64 tooth 16 DP or 4-1/8" OD. A 127 tooth 30 DP gear would be 4.3" OD, a 127 tooth 24 DP gear would be 5-3/8". Another ratio you might find interesting is 71 / 113 = .628318584 = pi / 5 to an error of only 85 parts in one *trillion*. This would be useful for cutting DP or metric module threads. Anthony ------- Date: Thu, 6 Mar 2003 16:13:25 -0800 From: "S or J" Subject: Re: 1" 10TPI Tap >Subject: 1" 10TPI Tap >Hi, Anyone have a source for these? A loaner? Cheers,Derf Hi Derf, KBC Tools has these listed as Special Thread Taps available in a relatively economical imported plug version. www.kbctools.com In U.S.A. 1-800-521-1740 In Canada 1-888-522-8665 MSC has at least 2 makes (domestic & imported) listed as Special Thread Hand Taps in plug, taper, and bottoming. The U.S. versions are quite properly more expensive and of known quality. Your choice. www.mscdirect.com In North America 1-800-645-7270 Probably only necessary to have the plug version, unless you have a blind hole needing threads very near the hole-bottom, where the bottoming tap will be useful. As usual: the normal caveat about being careful about shipping methods and very high costs for some options. U.S. or Canada regular post are still the best bargains, unless you absolutely need something overnight. In any case, you will want to lathe single point thread to near finish size before using the tap. Then the tap will align more easily and bring the thread to finished size. Before buying the tap, you might want to practice trying to get a good thread by lathe alone. If you have a project where the threaded article cost a fair bit (say a commercially cast backing plate), try practicing first on scrap steel until you are comfortable with the procedures. Also note the little known practice of converting your one and only tap in a size from taper to plug, or from plug to bottoming if you really need the second type -- right now. Do this by grinding off the tip (while thoroughly and regularly cooling it during the process to keep the hardness.) Of course this practice is psychologically easier to do if the tap is in a fairly small size and hasn't cost you a near fortune. Chances are some member of the group is a short drive away, but doesn't necessarily know where you are. For that matter, everyone posting to this group could benefit if their hometown and state/province/country were in the signature of every message :-) Good luck. Steve in Thunder Bay, Ontario, Canada http://www.janellestudio.com/metal/ for more machining tips ------- Date: Wed, 12 Mar 2003 12:46:20 +0100 From: "Jan J. Kok" Subject: Re: American threads [sherline] Original Message ----- From: "Roger Jonsson LINE AUDIO" Sent: Wednesday, March 12, 2003 11:43 AM >Hi, I need some more screws for my sherline mill tooling plate. They are "10-32". Is that and American thread only or is it translatable to something I can find here in Europe? What is the name of the American threads /system? All the best, Roger Jönsson. < Roger, The American threads have no direct metric equivalents. The 'funny' system works with either a number like #6 or #10, or a ratio like 1/4 or 5/16 or 3/8 in inches which is related to the size (diameter) of the bolt. The second number gives the kind of thread used, like 32 or 20, which is related to the number of turns per inch. So, the bolts "10-32" have a size of #10 and a thread of 32. Expressed in millimeters #10 corresponds to 4.8 mm, which is less than the 4.9 mm of a metric M5 bolt. Since for these particular bolts also the threads are almost equal, it is possible to use a M5 nut on a #10-32 bolt, but not the other way around. Such practice is not recommended, however. And it doesn't work with other sized bolts. I was not able to find a supplier for American bolts and nuts in the Netherlands, unless I ordered in quantities of 1000 or higher. To avoid any mounting problems for my Sherline lathe and mill I then ordered them in smaller quantities, but in many different lengths, in the USA (Small Parts Inc. is a good source, for instance). Jan Kok Eindhoven, Netherlands. ------- Date: Wed, 12 Mar 2003 13:05:27 -0800 From: "Dave Hylands" Subject: RE: American threads Here's a good reference for the numbered machine screws and what the various major/minor diameters are: http://cfa-www.harvard.edu/~masermri/screws/screw1.html This also includes some of the common fractional sizes (starting at 1/4") as well. Here's a chart that mixes the metric/imperial on one chart to give you approximations: http://www.gfii.com/it/technical/tapdrillchart.htm Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Wed, 12 Mar 2003 22:01:03 EST From: catboat15x~xxaol.com Subject: Re: American threads isaklx~xxtx.technion.ac.il writes: > Could someone explain what does the #6, #10, etc means. > How do you convert #number into In or mm ? I think I read someplace how to convert screw thread numbers into 1/1000 of inches, but I have a chart on the shop wall that does that for me now. But the really funny thing is that small machine screws are sized by numbers and higher numbers are larger IE, a 4-40 screw is much smaller than a 10-32. but when you drill the tapping hole you use drills that are sized so the smaller drills have higher numbers. IE a number 40 is about right for the smaller screw thread mentioned while the number 10 thread would need something like a number 20 drill. The only ones I keep in memory are a #30 drill makes a nice running fit for 1/8 inch rod. I can't recomend the American system to anyone, nor could I ever figure out the old Brit money system when I was there a short time before D day. Later in my life I was on the U.S. federal committee to encourage Americans to use the ISO system. Died a horrible death, when members kept asking, "Well, that is fine, but how do I measure 1/16 of an inch?" I know of three distinct "metal gage" used here also. Even for the shooters, shot guns are gauged by the number of lead balls that fit so a 16 gauge is larger than a 20 gauge, but then we toss in a .410 which is a direct measure of the bore. Maybe it all ties back to trade secrets? paul5910x~xxyahoo.com writes: > I do have a Home Depot (hardware store) down the street. Be sure to try the nuts on the bolts at Home Depot! I purchased some 1/4 X 20 bolts at our local HD along with nuts and washers. Got home and found the 1/4 X 20 nuts would not screw onto the 1/4 X 20 bolts. Bolts seemed a little large so no problem I thought; could just chase the thread with a 1/4 X 20 die. Split my die right in half, dont have any idea where those bolts came from, but too hard to cut with anything I had. Also ran across some valves (not from HD) that were threaded "inch size" but with a pitch that was metric or ISO. The valves came from Italy. John in the high desert of California 12 inch Atlas Mini Mill Rusty file ------- Date: Thu, 13 Mar 2003 10:41:28 EST From: Gdavis5000x~xxaol.com Subject: Re: Digest Number 1070 sherlinex~xxyahoogroups.com writes: > Could someone explain what does the #6, #10, etc means. > > How do you convert #number into in or mm ? To get from numbered size screws to OD, try this formula: OD=0.060 + (n x 0.013) Example: for a #8 screw OD = 0.060 + (8 x 0.013) = 0.060 + 0.104 = 0.164 just like it says in the tables George D ------- Date: Thu, 03 Apr 2003 23:45:38 -0000 From: "ggfinger65" Subject: Thread Cutting I own a 4400 lathe and a 5400 mill and enjoy them very much. I need some help with thread cutting. i am planning to buy the thread cutting attachment fot the lathe. I want to cut very fine internal threads. The thread pitch would be close to what one might find on a camers lens filter or watch case back. Is there a tool company that may sell a ready made internal thread cutting bit that is capable if cutting internal threads between .500 to 2.00 of an inch. I thought I could just buy a standard 60 degree threading bit and cut it really short. Im afraid that the tool post will get in the way or that the inside diameter may be to narrow for the cutter to have enough clearence. I dont think that I could grind one that small and keep it accurate enough to do a proper job. If anyone has a solution for me I would be able to sleep like a baby again. thanks RobG ------- Date: Thu, 3 Apr 2003 16:31:14 -0800 From: "Dave Hylands" Subject: RE: Thread Cutting Hi Rob, I haven't yet cut internal threads, but I'm planning to, so I've been looking at what to do. This page: http://easyweb.easynet.co.uk/~chrish/tscrewct.htm#ithreads has some useful information. Basically, I see the following options for cutting internal threads: 1 - Use a tap 2 - Use a boring bar with a small HSS bit with the appropriate cutting angle 3 - Grind yourself a one piece HSS bit. Sherline sells a single piece boring tool that would be SIMILAR to what you would need to do: http://www.sherline.com/images/3007pic.jpg 4 - Find a tap with the right pitch, but a smaller diameter than what you need. Grind away part of the tap and use it like a boring tool. You could either use this like a single point tool, or leave a bunch of teeth. The portion you would need to grind away would be the portion above the cutting teeth (at least I think you'd need to grind it away. Maybe you can just use the tap "as-is" but I haven't tried this yet. I think that option 2 is the best. If anybody else has any experience/advice to offer, I'd appreciate hearing about it too. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Thu, 03 Apr 2003 17:42:29 -0800 From: "Scott A. Stephens" Subject: RE: Thread Cutting I tried internal threads with the Sherline. But the problem I had was the tool post keep spinning. I tightened it the usual amount for my regular work. But as I would cut the tool post would swing away from the work as I brought the cutting bit in. Shortened the bit. Finally figured for what I was doing a tap would be easier. External I have had no problems with. Just if you use an insert, make sure you do not leave the bit in when you reverse the work. I ruined one carbide insert that way. But once you get past the learning curve it is pretty easy to do. ------- Date: Thu, 3 Apr 2003 20:49:12 -0800 From: "Marcus & Eva" Subject: Re: Thread Cutting Hi Rob: Grinding toolbits is difficult for many beginners, and formtools are among the most challenging. (threading tools can be regarded as a kind of formtool.) To do it really accurately really requires a cutter grinder, but there are a lot of good ways to fake it if you don't just happen to have one of those kicking around. For your particular application, the best tool is a solid High Speed Steel boring bar made from a 3/8" diameter toolblank 4" long. This is a standard size that can be acquired at any tool supply house for a couple of bucks. The best way to do most of the shaping, believe it or not, is to turn the body down in your Sherline lathe using a carbide tipped toolbit. A good hard carbide grade is helpful, but the standard grade supplied by Sherline will work well too. Two things about hard turning on a tiny lathe like a Sherline: 1) Keep your part chucked up as close to the 4 jaw as you can (this is not a real good job for a Sherline 3 jaw...I've found they don't quite have the grip strength needed for hard turning) 2) Take light cuts at moderate speeds....600 to 800 RPM on a 3/8" diameter is plenty, and your cut should never be deeper than 0.010". 0.005" is more like my usual cut depth. So, you rough down the shank, leaving a bit unmolested right at the tip. This last bit should be about 0.060" wide. The necked down portion should be 0.0625" deep, leaving a diameter of 0.250", and shouldn't be much over an inch long. Now you will split the end of the blank, completely grinding away one half of the diameter, but only at the very tip where you left the diameter 3/8". Try to get the split exactly in the middle. Next you will put the point on the tool. To do this freehand can be pretty tricky; your safest way is to take advantage of the controlled movement that the Sherline has. So it's simply a matter of getting the toolbit mounted in the right position, getting a little grinding wheel in the spindle, and protecting the ways of the lathe so the grinding grit doesn't trash the machine. You'll need a toolpost for the new boring bar anyway, so this is a good time to make up a gadget that will give you both a toolpost and a grinding jig. A cube of aluminum, the same size as the toolpost that came with the Sherline, with a big clamping hole and a 3/8 bore sideways through it at the center height of the lathe will do the job well. Slice the top off at a 5 degree angle, and you've got your jig by simply flipping the block upside down.You need the big clamping hole to accommodate the clamping screw through the block when it's tilted. The 5 degrees is to give the ground faces of the tool some clearance so they don't rub in the cut. A setscrew in the side of the block to lock the toolbit in place and you're ready to go. Grind the back flank of the tool first, and then grind the front flank until you get a dead sharp point at 60 degree included angle. Then just lightly kiss the point with a very fine hand stone so you can just see a teeny flat on the tip of the tool and you're done. This all sounds dreadfully complicated, and it is a bit time consuming...but it's not nearly as bad as it sounds, and with care, you'll have a tool you can use for years.I've got tools I made twenty years ago, and I still use them daily. If all this makes you grit your teeth with impatience, then you can just hack a 60 degree point on the side of a 1/4" square toolbit, clear the side behind the point by grinding the snot out of it on the bench grinder, and start carving away. Give it lots of clearance and don't cut too aggressively with it. Oh yeah, and when you grind the clearance...grab the toolbit in two pairs of vise grips...it's going to get really hot when you grind it. You can't hurt HSS by grinding it aggressively...make it nice and blue if you want...even dull red's OK. These really fine threads don't need much in the way of a toolbit, and if you're out a couple of degrees, it makes almost no difference on these short thread flanks. Hope this helps. Cheers Marcus ------- Date: Fri, 4 Apr 2003 00:52:23 EST From: catboat15x~xxaol.com Subject: Re: Thread Cutting dhylandsx~xxbroadcom.com writes: > 4 - Find a tap with the right pitch, but a smaller diameter than what you > need. Grind away part of the tap and use it like a boring tool. That is an old way to cut threads, called chasing a thread. Before taps and dies were so common and inexpensive that was the way it was done. Used by clock and watch makers also. I understand it was quite a skill to hand cut a thread with a chasing tool. ------- Date: Fri, 4 Apr 2003 08:22:32 -0500 From: "Carol & Jerry Jankura" Subject: RE: Thread Cutting I was thinking about this internal threading thing... I can understand why the tool holder may want to rotate because of the lever arm between the bolt holding the toolholder to the cross slide and the tip of the cutter is quite a bit longer than th elever arm when the tool is perpendicular to the axis of travel. Which got me thinking - why not make a tool holder that had a bar milled in the bottom to fit into the slot in the cross slide and then use a simple 10-32 bolt and nut to hold it in place. The bar would prevent the toolholder from rotating. Or, why not make a toolholder that had had places for two bolts to hold it to the cross slide. After all, threading, I don't really see the need to be able to rotate the toolholder like you might want to do for turning operations. Is there any merit to this? Jerry ------- Date: Fri, 4 Apr 2003 07:34:33 -0800 From: "Dave Hylands" Subject: RE: Thread Cutting Hi Jerry, Sounds entirely reasonable to me. You could just have a "key" as an integral part of the tool holder (as you suggested) and have a gap in the middle where the bolt/T-Nut goes. I'm glad you suggested it. The only disadvantage I see is that you lose adjustability for getting your tool lined up, but that's probably not that big a deal. By using two bolts (also as you suggest), one of them could have a slot rather than just a hole to allow some amount of adjustment. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Fri, 4 Apr 2003 09:14:21 -0800 From: "Marcus & Eva" Subject: Re: Thread Cutting Hi Randy and Dave: Thank you very much for your kind comments...I really love to try to get others into this hobby and past some of the hurdles that used to frustrate me when I first began. So it's great to hear that it's working for you. Dave...you've got the idea exactly right in your posts to the files section. For all those who had difficulties visualizing what I was gabbling on about, I recommend you look here: http://groups.yahoo.com/group/sherline/files/Internal-Threading/ These pictures come courtesy of Dave Hylands...thanks Dave!! A couple of comments though...You'll have a really hard time trying to get the right angled internal corners at both ends of the necked down section, and you don't need them anyway. So your pictures are an accurate description of what I said, but you need not achieve anything nearly so nice. The objective is merely to neck the tool down in an efficient way, and the lathe is the best way I've found if you don't just happen to have a cylindrical grinder or a tool and cutter grinder kicking around. While we're on the subject, it is possible, and perhaps very desirable to turn the 60 degree point on the side of the tool before you try to split the blank. This gives you a nice target to work to when you grind the relief, and in fact, removes enough material that you can Dremel or even hand stone the last bits away. The other thing you'll notice, is that you can, in fact achieve two cutting edges; one for external threading and one for internal threading on the same tool. This is a further incentive to try to turn the two 30 degree flanks before splitting the blank. Now, if you want to get REALLY tricky, and avoid all the grinding nonsense, you can arrange to have the tool mounted a bit above center, and grind the flat shown in Dave's JPEG #2 down below the center of the blank by the same amount as the toolbit was raised. Very little is needed, and what you get is equivalent to a radially form-relieved tool ( most involute gear cutters are radially form relieved...very desirable and very expensive!!) If you raise the tool 0.010" above center, that's enough. Of course it means you have to get tricky with the boring of the toolpost hole...I'd just block up the headstock 0.010" with a pair of feeler gage blades, mount the toolpost on the cross slide, and have at 'er. Jerry Jankura made a comment too that I think is an excellent idea...that is to put a key under the toolpost (or two mounting screws) to keep the toolpost from rotating. If you want to preserve the ability to rotate the toolpost, a removeable key will do the trick...if, on the other hand, you wish to dedicate the toolpost to threading and want to know that you've set up perfectly square every time, then you can machine the male key directly on the bottom of the toolpost. Proud Sherline mill owners will be able to do this easily...for those who have only the lathe, I recommend the removeable key, because you can get there simply by laying the toolpost on its side and clamping it to the cross slide to mill the slot. Chuck up a 1/4" endmill (collet, endmill holder, or 4 jaw chuck please!!!) and you are good to go. Cheers Marcus. PS: I'll happily consume a beer in honour of the hobby machining fraternity. Thanks most kindly. Side note to Dave...I'm getting a lot of pressure to sell the fancy Sherline quill to another one of my buddies. C'mon over at your convenience, so we can get our plans in place to get the design out into the world. For those who have no idea what I'm on about...I came up with a super quill design to allow heavier drilling on the Sherline mill than the attachment pioneered by Ron Ginger and now sold by Sherline. I made a prototype and sent it to Joe Martin to see if it could be commercialized. He couldn't figure out a way to make it for a reasonable price point, so I've got it back. Dave expressed interest in building a copy, and perhaps getting the design out on his website. Now everyone who gets a look at it wants to buy it off me...and I'm having to hide it from view in order to keep the peace in my shop. ------- Date: Fri, 04 Apr 2003 20:52:21 -0000 From: "n2562001" Subject: Re: Thread Cutting Rob, for the camera type thread you can use the solid carbide Micro 100 internal thread cutting bars. In fact I just used one to cut a .219" x 80 internal thread for a 1/8th scale grease gun. You can look at them on their web site at www.micro100.com . They are about $20.00 retail. Jerry Kieffer ------- Date: Fri, 4 Apr 2003 20:37:08 -0500 From: "Marshall Pharoah" Subject: Re: Thread Cutting I didn't modify my toolposts, but I did cut a small bar of 1/2 or 3/8 square stock about 5 inches long, with a hole in one end and a slot in the other. After I get the toolpost where I want it, this is adjusted up against it to keep it from turning. Pretty simple, but works well. Also, clean and degrease both the toolpost and the cross-slide, this will be all you need in many situations. Marshall ------- Date: Sat, 5 Apr 2003 11:11:10 -0500 From: "Tracy Atkinson" Subject: Re: Thread cutting Re keeping the tool post from turning, two holes drilled vertically through the block and filled with pins make a simpler alignment device than cutting for a key. Tracy Atkinson, Avon CT ------- Date: Fri, 11 Apr 2003 13:40:43 -0400 From: "Thomas R. Bank" Subject: Re: (Internal) Thread Cutting I'm getting in here late. I just got back from out of state. The info responses already posted are good and I appreciate the insight, as always. The one thing I would add regarding the project described, which I am also thinking about working on, is that thin rings are hard to thread, especially when in aluminum. The problem is that the ring, if held in a jawed collet, will deform and you won't get a circular thread. Also, since aluminum is malleable the final product tends to lock in place when screwed into position. I would suggest cutting an oversized disk and fixing it on a face plate. Then bore the internal opening and thread it, after which you (we 8^) ) can externally thread a stub of bar to match the internal thread, spin the project piece into position, and do the outside of the ring. Finally, if we are lucky, we can unscrew the finished ring from the stub and use it. I have some LaBelle powdered teflon and powdered graphite. I'm thinking of using one or the other on the threads of my ring before screwing it to the stub. Anyone have any suggestions on which would be preferable? Thanks in advance, Tom Bank P.S.: What I am trying to do is make an externally mounted (bayonet) step-up ring for my digital camera. My camera zooms to 28 mm equivalent, at which setting a polarizing filter causes vignetting in the corner of the pictures. A normal step-up ring will do the same. I hope this approach works. I already have the filter which I kept when I gave my 35 mm camera and lenses to my son. ------- Date: Fri, 11 Apr 2003 19:00:53 -0700 From: "Marcus & Eva" Subject: Re: Re: (Internal) Thread Cutting Hi Thomas: Thin rings can be most easily made by chucking up a solid bar and boring out a pocket in the end, then turning down the OD to size. If it's extremely thin, you can pack some plasticene into the finished bore before turning down the outside. The plasticene will keep the cutter from screaming as it contacts the thin wall. I've turned thinwall canisters 4" diameter and 4" deep with a 1/16" wall using this technique. After you've turned all the features, you can part it off the bar. You might also want to consider using a hard grade of aluminum... 7075 T6 or Alumec 89. These harder grades are much less prone to galling. You might also wish to anodize the parts. Lubing them with graphite or teflon shouldn't be necessary if they're anodized, but I don't think it can hurt. Cheers Marcus ------- Date: Tue, 15 Apr 2003 21:26:02 -0400 From: "Kevin J Wilby" Subject: help with threading this is just another general question, what is the attachment to the lathe in the tailstock that holds die's to be threaded into parts that are held in the chuck? thanks kevin ------- Date: Tue, 15 Apr 2003 22:45:45 EDT From: HUNLEY31x~xxaol.com Subject: Re: help with threading Kevin, I use a regular die holder with a drill pad in the tailstock in contact with the die holder. Sometimes a drill chuck with the jaws retracted will help in the same way. Just slight pressure is all that's required to keep things aligned. I was going to make a tailstock die holder when the need arises, but so far I've never needed one. Larry ------- Date: Wed, 16 Apr 2003 03:14:13 -0400 From: "mertbaker" Subject: Re: help with threading This is called a die holder, and I think someone may sell one that fits your machine, but it's a good first project to make yourself. I can send you a pic of the one I made for may 7x, if you want; it has a #3 taper on it, but you can make one with a #1 to fit your lathe. Mert ------- Date: Thu, 17 Apr 2003 16:57:34 -0400 From: "Art Herrick" Subject: Re: [ atlas craftsman ] Help with threading Kevin, if I understand your inquiry, you wish to form small size threads on your lathe [ say 4-40 threads, and under ], and want to know how to hold thread dies [ or taps ] in your tail stock. I am a model shipwright, and use tap and die sizes down to 0.40 mm (UNM), where potential tap breakage is a real problem. Unless one has precise mechanical means to delicately finger feed minature taps and dies into the work piece, while keeping them in perfect alignment, custom made tap and die holders, with the ability to rotate and feed the holder into the work piece is my answer. Say at the very maximum, about 1/4 inch of in-feed is all that I need. First I have machined a precision mandrel that fits my tailstock, and has a 3/8 inch in diameter x 1 inch long precision shaft. I own a model #3950, 6", Atlas/Clausing lathe (circa late 1970s), and also have a mandrel machined to mount on the tailstock on my small 3.62" x 7.9", Unimat 3 lathe (1985), and another mandrel for the spindle of my Atlas Press Co., Model #104, Mini vertical mill (1997). Next I have made tap and die holders for the three different types of miniature tap and die sets I own, that are a precision slide fit on the 3/8 inch diameter mandrels of the three machines above.. The holders all have a 1 inch diameter x 3/16 inch wide ring, which have a knurled surface, which gives me a secure finger grip on the holder, when turning the tap or die to thread a workpiece. The feed is automatic because the new threads in the workpiece draw the holder along the mandrel and towards the workpiece. To avoid tap breakage in extremely small size taps, and obtain precision threads, it is strictly an educated finger feel of what the tap or die is doing while you are feeding it into the work piece, and one is constantly backing the tap or die off, and cleaning the chaff, so the new threads do not clog up. The proper lubrication for the type of material being threaded becomes extremely important, and in my case I use ... kerosene for aluminum - soluble or light base oil for brass, bronze or copper - sulfur based oil for nickel or steel - lubricating wax for plastics. As for the design of the tap and die holders, just use your imagination, depending on the design configuration of the particular set, or sets, that you own. I have no drawings or photos available of my three mandrels or for the tap and die holders, and do not intend to make any, because there are too many variables involved in different machines and the design of miniature thread tap and die sets. Art Herrick Westmoreland, New Hampshire USA ------- Date: Wed, 16 Apr 2003 22:54:57 -0500 From: Jon Elson Subject: Re: Turning threads [NOTE TO FILE: While this subject has been well covered above, this message describes the process well and contains two wrinkles -- feeding straight in vice using compound at traditional 29 degrees, and consideration of a sometimes shaky old lathe. Note also, the thread dial setting for engagement may be different if cutting a thread different from the leadscrew; this message is aimed at specific practice to cut the same thread count as the chuck when the leadscrew has exactly the same thread count as the chuck.] >Can someone fill me in on where to get information for using the >lathe to cut threads? I would like to Build a threaded back plate >for a new chuck. I think that starting with external threads would be >a good start. Yes, external are a lot easier to see, at least! You need a tool with a 60 degree point for most threads, including Atlas spindle threads. You need to set up the gear train for the correct thread pitch. This one is easy for the Atlas 10 and 12" lathes, which have an 8 TPI thread. The main leadscrew of the lathe ALSO is 8 TPI, so the leadscrew must have a 1:1 ratio to the spindle. Exactly one leadscrew revolution for each spindle revolution. There is a threading dial, that allows you to engage the halfnuts at a proper point on the leadscrew to re-engage with the existing thread for each pass. This is no problem in this case - any place the halfnuts will engage the leadscrew is fine, since the thread is the same. What you do is make a place at each end of the threaded length where the diameter is cut down to the minor diameter of the thread. The OD of the place to be threaded is turned to the nominal thread diameter. There is a tool made out of sheet metal that allows you to align your threading tool straight in to the workpiece. You place the straight side against the work, and the tool should fit exactly into the 60 degree Vee on the other side. You also want the top of the threading tool to be at the center height of the work. You advance the tool in toward the work until it is just about to touch, move the carriage to the right until the tool is pointed at your start place, and then turn it in, perhaps .010" or so. With the spindle turning at a slow speed, such as 60 - 120 RPM, you engage the halfnuts. When the tool feeds across the work to the left and is cutting air at the stop area, you disengage the halfnuts. You back the crossfeed out so the tool will clear, and roll the carriage to the right. You then feed in a few thousandths deeper than the last pass, and repeat. Depending on the material, the rigidity of the tool, the speed, and the coarseness of the thread, you may have to decrease the infeed increment to .001" in some cases. Some guides recommend setting the compound to 29 degrees and using the compound feed to advance the tool into the work, and using the crossfeed to back out for clearance and then come back to the same setting on that feed every time. My experience is this leads to a wider chip on one side, and causes worse chatter than feeding straight in to the thread. You will find cutting an 8 TPI thread that chatter will be a problem on the Atlas machines. It is doable, but you will have to select the best speed and feed to keep things from shaking badly. Jon ------- Date: Fri, 18 Apr 2003 11:20:59 -0500 From: Jon Elson Subject: Re: craftsman 101.21400 cantstop47 wrote: >Help! When I lock my half nut down, my thread dial stops turning. >Have tried everything I could think of. rlandesx~xxcomcast.net Thanks, Of course! It is supposed to. When the half nuts are engaged, the carriage begins to move in sync with the leadscrew thread, and the dial will stop turning. Jon ------- Date: Fri, 18 Apr 2003 21:40:40 EDT From: catboat15x~xxaol.com Subject: Re: Digest Number 1443 That is correct. When the half nuts are engaged with the lead screw there is no relative motion between the carriage and the lead screw so the dial stops turning. The dial indicates the relative motion between the carriage and the lead screw so you can engage the half nuts at the proper location on the lead screw threads. How else to explain? Visualize one thread of the lead screw. When the carriage is stationary the thread on the lead screw is advancing past the carriage and turning the thread dial. Then when you engage the half nuts the thread is no longer moving past the carriage as the carriage is being moved by the lead screw so the dial is stationary. When you are not threading the dial is not of much use and by loosening the screw that secures the threading dial to the carriage that little gear on the dial can be swung out of the way. Conversely I have fouled up a thread by not having the gear fully engaged with the lead screw to where it has skipped a tooth or so. John in the high desert of California 12 inch Atlas Mini Mill Rusty file ------- Date: Mon, 21 Apr 2003 23:06:42 -0000 From: "Damon" Subject: Making a tap ? I know this is probably a rookie question, but if anyone wants to add any insight, I'd be really appreciative. I'm trying to tap some holes 7/8-18, and made taps (RH & LH) I drilled the holes to .813, root of thread is .802. Taps were made from O1 steel, with about 1" of normal thread and another 1.5" of tapered thread. Ran the taps on the mill, cut 3 flutes 1/8" deep with a 1/2" ball end mill. Heated them to a cherry red glow, dunked in oil. Still seemed soft so I did it again into brine. Quick pass of a file on each tooth to clean. In practice these things are an absolute bugger to turn. (age 30, 6', 200#, broke two wrenches on the taps). Also the material tapping is 1025. In 4 hours, I've got one hole that will take a bolt 1/2". I need 4 holes tapped to 6" and think I'm losing this war. Is there anything obvious that I'm doing wrong, or overlooking? Something special about tap shape for efficient cutting? Or is this just one of those lousy jobs where it's best to cut a roughing tap. But then again this is a 0.030" deep national v form, not exactly a big thread. Yes, using lots of oil! TIA, Damon ------- Date: Mon, 21 Apr 2003 18:12:34 -0500 From: "Rodent" Subject: Re: Making a tap ? I assume you are tapping steel? Try using Tap Magic or some stinky 80/90 weight gear oil -- regular oil does not work as well. ------- Date: Mon, 21 Apr 2003 23:36:48 -0000 From: "mendoje1" Subject: Re: Making a tap ? Just to start, I AM the definition of a rookie! I havent made a tap, but I recall that the flutes on a tap are not centered, but offset a bit from centerline to get the right rake angle. If the flutes are centered, could this cause the high turning effort? Jeff ------- Date: Mon, 21 Apr 2003 17:41:19 -0600 From: lynn.chidesterx~xxxtp.varian.com Subject: Re: Making a tap ? Many of the older machining books deal with tool making, and mfgr of taps (and other tools that we modern folks get used to just buying). While it is possible to cut threads with grooves cut lengthwise in a hardened threaded shaft (or bolt), taps have some (back)relief cut into the threads so that only the front part of the flute is contacting the material to be threaded. From my reading of your email, I wonder if your tap has any relief to the flutes. I not (=no relief), this might explain why you are having difficulties. I think that providing the relief could be difficult, since the single point threading tool must move in and out in sequence with the flute rotation during the tap threading and manufacture. Have you considered PURCHASING the taps you need from a tap manufacturer? Even if the thread is not a standard, it is my experience that if the manufacturer has the tap blanks on the shelf (and they most often do, unless you need a REALLY strange tap), a custom tap from a tap manufacturer can be in your hands in an amazingly short time. MSC and other tool dealers often have a section for "standard non-standard taps", which can be ordered from them as a standard catalog item. Example: my 2000/01 MCS catalog lists 7/8-18 special taps (in plug, bottoming , and taper configurations) as std. catalog items x~xx$26.65 each, with GROUND threads. If not, talk to someone like Regal-Beliot or Greenfield who mfgr's taps for a living. I think you'll be PLEASANTLY surprised at the quoted price and delivery for your custom tap. And lastly, I think your tapping will go much easier AND faster, and you'll produce better looking threads! ------- Date: Mon, 21 Apr 2003 22:40:36 -0400 From: Stan Stocker Subject: Re: Making a tap ? Hi Damon, common home made tap problems: Did you offset the endmill from center or index the tap so that you have around 5 to 7 degrees of rake to the cutting edges? Trying to scrape rather than cut threads will create lots of work. Are the threads relieved behind the cutting edges? While nifty automated cam fixtures are sweet for making such things, you can do it by file/grinder/even on the mill with care. Did you take some steps to really clean up the cut threads on the tap, such as lapping with fine arbasive on a hardwood lap? If your cut threads are really clean this isn't required, but it sure can make a difference. Did you hone the cutting edges after heat treating? Now for the BIG question :-( Am I reading this right? You want to tap 6 inches of thread into four 0.813 inch holes? This just plain sounds odd to me, I can't recall ever seeing something with six inches of thread all the way through the bore in this small a diameter. Getting the thread lead accurate enough to allow correct engagement over the entire length alone would make this a pretty tough deal to pull off, ignoring the difficulty of getting the threads cut in the first place. Is this a must, or can a different method be used? A full inch of thread engagement probably gets you to the point where the hardware will yield at lower stress than the threads can take. Can you fill us in on just what you're working on? I think there are probably other ways to get where you want to be with a lot less hassles. Cheers, Stan ------- Date: Tue, 22 Apr 2003 10:35:09 -0700 From: "Bob May" Subject: Re: Making a tap ? You probably don't have any back relief on the threads and the rake is probably at or near 0. This does tend to make a tap hard to turn along with the fact that you probably didn't stond a sharp corner on the edges of the thread cutters. You will probably want to resoften the tap and redo it so that it has everything right. A thread file will probably do fine for making the relief (leave about .050" or so proud for the cutter and taper in the rest) and a retouching with the mill will put rake on the teeth. After hardening, stone the face of the mill cut so that the cutter is sharp. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Wed, 07 May 2003 22:10:11 -0000 From: "Steve Black" Subject: inside threading Hello-well,I'm slowly building up the gumption to start on a spiers style woodworking plane, and the heart of the adjustment is a threaded shaft thru a captive nut (sort-of-I won't bore you metal guys with the intricacies of a 100 year old wood plane) I kinda see the shaft at about 5/16-3/8 and I kinds see the threads at 32. I'm sure the old atlas will do the shaft, but the idea of threading inside hole 32/inch is scary-and I'll bet a peanut butter sandwich that there is no tap like 5/16 by 32. Any suggestions?-Also thanks for the help with the lead screw bearing replacement-made the kind with a slip fit oillite sleeve and aluminum pin-not elegant like the curvy 30's style bracket. but very functional Steve in Sacto ------- Date: Wed, 7 May 2003 19:54:10 EDT From: PIHPGSx~xxaol.com Subject: Re: inside threading Hi, don't know what lathe you have; if you have a q/c box, set it up to 32th inch and use a left hand 90 % boring bar ground to 60%. Boring bar of course mustbe very small +- 3/16 inch. Take as many lite passes as needed to reduce hogging or vibration on bar. Plenty of oil helps prevent chatter on this hope it helps chuck ------- Date: Thu, 08 May 2003 02:28:54 -0000 From: "KDSpriggs" Subject: Re: inside threading > I'm sure the old atlas will do the shaft, but the idea of threading > inside hole 32/inch is scary- I recently made a micrometer stop for my 12 inch Craftsman. As you no doubt know a micrometer uses 40 threads to the inch. I was just like you I thought the idea of doing an inside thread 40 TPI was pretty scary. It also was 5/16 diameter. At any rate I tried it and whatever it was beginners luck or fate it worked perfectly. I ground the tool from 3/8 inch square HSS. I used a MOTO TOOL with a fiberglass cut off wheel to do the final grinding on the tool. Verify that you have adequate clearance on all sides of the tool before starting. The other reply outlines the actual procedure better than I could. PS If I remember correctly I have a picture of the micrometer stop on the projects page. [atlas_craftsman group] ------- Date: Thu, 8 May 2003 13:35:40 EDT From: JMartin957x~xxaol.com Subject: Re: inside threading The big difference with inside threads is length of thread - you have to have the boring bar hanging out all the way. 32 tpi are easier than a coarser thread, as there is less chatter and the root diameter is greater. Or, you could make a tap. John Martin ------- Date: Thu, 8 May 2003 12:34:27 -0700 From: "Bob May" Subject: Re: inside threading If you never try it, you will never know if you can do it! Go for the gusto on some scraps and see what happens. If you don't get there right, set back for a moment and think of what you did wrong and how to do it right the next time. Odds are that you will do it right the first time and have a piece of scrap with a beautiful threaded hole in the middle of it. You may then be able to turn that scrap into another part for another plane. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Fri, 9 May 2003 22:39:51 EDT From: LouD31M066x~xxaol.com Subject: Re: inside threading A 100 year old plane likely has the screw fastener of the time. I believe Unified Thread Series is a more modern system. All that aside if you can identify the thread you can make it...maybe not perfect the first time but inside or outside once you set up the lathe all you have to do is remain moderately alert while your scew cutting engine lathe does its thing. Taps and Dies are handy, but, for larger size, odd thread one off jobs you will find cost favors doing it on lathe. True, there are a few variables that can mess things up, but, learn how to make threads on routine can't hurt jobs so you have the skill when you need to be able to make it right on a do or die job. Do not be afraid of threading ...it is one ot the things that once learned will pay you back many times for the effort. Your lathe is set for inch based threads, but, as has been pointed out many times it can be geared up to do acceptable metric also. Atlas stated in lathe manual that making threads could be a profitable use for your lathe. Get some stock and practice...by the way there is more leeway in making threads than you might think...in fact a too perfect thread would likely be too tight to use. Louis ------- Date: Mon, 12 May 2003 21:17:47 -0000 From: "azbruno" Subject: Leadscrew and threading dial on 6" 101.21400 I'm starting to do threading on my lathe and find that the documentation about use of the threading dial in the Atlas Manual of Lathe Operations for 6" lathe differs from what I'm seeing. I'm set up for 10 TPI. The book says for an even number of threads to engage the half-nuts on a mark, and subsequent passes on the same or opposite mark. But I find that subsequent passes can be made on any of the four quarter marks. The leadscrew is 16 TPI and the threading dial has 32 teeth, so there are two inches of carriage travel and 32 points of engagement for the half-nuts on one rotation of the dial. My plan is to do double or quadruple leads and now I don't trust the book. I've been able to figure it out with the 10 TPI gearing, but I also found it is very easy to accidently hit the wrong point when engaging the half nut. Has anyone done this kind of threading and have any advice for making it easier. Also, does anyone have the documentation that describes the use of the threading dial given this configuration. Many thanks, Bruno ------- Date: Tue, 13 May 2003 10:33:01 -0400 (EDT) From: Kirk M Scammon Subject: Re: Leadscrew and threading dial on 6" 101.21400 Bruno, I once worked on a part that required a triple lead thread to accept an optical piece. For that job, I built an indexing fixture to fit in the chuck that allowed the part to be taken out, and indexed 120 degrees after the first set of threads were cut. I then cut the next set of threads using the same mark from the dial. After the second set was done, the part was indexed another 120 degrees, and the third set of threads was cut using the same marker on the threading dial. I don't know if it this will work for your project though. Regards Kirk 12x36 A/C and MF mill ------- Date: Tue, 13 May 2003 15:41:41 -0000 From: "azbruno" Subject: Re: Leadscrew and threading dial on 6" 101.21400 In the same vein, I did think about indexing the threading dial - assuming the right multiple of leads - by engaging the half nut to keep the carriage in position and then slipping the thread dial the right number of teeth. If that does not work out right, I could possibly slip a threading gear, but that would require being very careful. My biggest problem is that there are 32 points to engage the half- nuts and it takes a lot of care to not miss by one, especially with lots of passes. It is easier to engage on a mark, not between. Bruno ------- Date: Tue, 13 May 2003 11:47:21 -0400 From: Damon Gentile Subject: Re: Re: Leadscrew and threading dial on 6" 101.21400 When in doubt, engage on the same mark if possible for the pitch you are cutting. For multiple start, cut one completely and draw indlex marks on the geartrain. Remove an idler gear, rotate spindle (120 deg for you) then engage the idler again. Start a fresh thread, using the same mark. When done with that, do it again for the 3rd start. -d ------- Date: Tue, 13 May 2003 09:28:38 -0700 From: Frank Evan Perdicaro Subject: Re: Digest Number 1471 [WAS Re: Leadscrew and threading dial on 6" 101.21400] It is not always possible to pop the idler gear (or QC box) and do this re-entrant trick. Sometimes the numbers will simply not work -- when there is no integer relationship between the drivetrain and the number of screw pitches needed, you have to remove the part and rotate it. For example, if you need a 3 or 7 lead screw, you generally cannot use the gear method. The reason is because if you look at the prime factorization, or lattice analysis, of the gear train and compare that to the lead count there are no prime factors in common (they are relativly prime). By chance I am just about ready to file a patent in a closely related problem. After four rounds of review, hopfully the last edit will pass to the patent atty. on this thursday. ------- Date: Tue, 13 May 2003 12:52:32 -0400 From: Damon Gentile Subject: Re: Digest Number 1471 Frank, Ive never tried this for something unruly like a 7 lead cut, but think about this and let me know if it would work... Try the reverse of what I mentioned earlier- Initially, establish the gear train to run an idler that is a multiple of the number of stars. Working the 7 lead example, let's say it's a 56 tooth idler. You complete the first thread then mark the gear train. Pop out the idler and advance the gears downstream of the idler by (idler_teeth / number_of_starts) In this case 56/7 = 8 teeth. Drop the idler back in and cut the second thread. Repeat as needed. Going this way bases the computation on the multiplication of integers, no dastardly common factors or even tied to the teeth on the spindle gear. Make sense? -d -------- Date: Wed, 14 May 2003 10:06:56 -0700 From: Frank Evan Perdicaro Subject: Re: Digest Number 1471 This idea of using an intermediate gear with the correct prime factorization will work. All you need is the at least one occurence of the prime factorization of the lead count in the geartrain, where the gear is accessible and can be indexed. ------- Date: Mon, 2 Jun 2003 15:58:31 -0500 From: "J.T. Travis" <1911_fanx~xxbellsouth.net> Subject: Re: British Threads >Where can I find a description of British threads, the small stuff >like 5BA and 7BA? Are taps and dies available for this on this side >of the ocean? Or should I just chuck them all and put in American >equivalents. I have not been successful in finding a chart with side >by side comparisons to see if any thing American is close. >Charlie in NC Charlie, I've seen them for sale in the US, can't recall the site at the moment. If you are building something from plans it would be a lot cheaper and easier to convert to UNC/UNF. Here's a chart with all the numbers: (did a google search for "british thread sizes" - lots of neat info out there.... http://www.enginehistory.org/BSFasteners/BSReference_3.pdf BA's are on page 6. I'm sure you could find the standards on the web to approximate them. Keep an eye out at flea markets and used book stores, perhaps you'll find an old handbook. I've picked up old machinist handbooks from time to time and they are nice to have - the material does change - some of the old ones have techniques suitable for HSM guys but that have been edited out of the more recent industry oriented editions. Joe ------- Date: Mon, 2 Jun 2003 18:50:05 -0700 From: "David" Subject: Re: British Threads Charlie: Machinery's Handbook, 25th ed., has the full skinny, beginning on page 1750. [SEE MH's TABLE OF CONTENTS IN OTHER EDITIONS] Dave Wood ------- Date: Mon, 2 Jun 2003 21:30:39 -0500 From: "Martin and Vanessa Dobbins" Subject: RE: British Threads Please be aware that 5BA and 7BA are not particularly small <> As the number increases, the item gets smaller, and BA threads run up (down?), I think, to 26 (approx 0.01" in dia). Your closest ASME size to 5BA is probably 5-44, and to 7BA is probably 3-48. Some ASME Taps will cut threads that will work for BA screws, what you have to watch is the pitch and the thread angle. For more (way too much!) information I can upload a spreadsheet to the group files, let me know if you would like that. Martin The Brit living in the Volunteer State ------- Date: Mon, 02 Jun 2003 19:59:39 -0700 From: Alan Marconett KM6VV Subject: Re: British Threads Try: http://www.mmmachines.com/ I've ordered BA taps from him. Alan KM6VV ------- Date: Mon, 2 Jun 2003 23:04:30 -0400 From: "Shorty Leatherwood" Subject: Re: British Threads Another source for the info you are looking for is in the book "Pocket Ref" by Sequoia publishing ISBN 1-885071-00-0 this book is full of good stuff and sells for about $10 it is available from many sources on the web. I am sure that a google search would find it. Shorty Not a Brit living in the volunteer state. ------- Date: Tue, 03 Jun 2003 09:29:18 -0000 From: "Graham Green" Subject: Re: British Threads Charlie, go join this group and look into the files section. The FIRST folder has exactly what you are after. http://groups.yahoo.com/group/mlathemods/files/ radish ------- Date: Tue, 3 Jun 2003 12:18:00 -0400 From: "Ron Ginger" Subject: Re: British Threads There are MANY British thread standards. Of interest to model builders are the BA series and the ME series. There is no good reason for an American to go to the trouble of using BA threads unless you have something like a Stuart Turner kit that supplies all the bolts. Then the advantage is that their bolts are nicely to scale for models- the heads are much thicker than US bolts, and the hex is better proportioned to suit a scale model. If you are making a nice scale model this is important, badly scaled nuts and bolts ruin the look of a scale model. Allen Screws on a scale model are simply ugly. One suggestion for better looking scale nuts in small sizes- use the next smaller nut and re-tap it- ie, if you are using a 4-40 bolt use a 2-56 nut and rethread it to 4-40. That makes the hex look about right in relation to the thread. To do this I put a 2-56 tap in the tailstock chuck, thread the nut onto it, then use that as a holder to grab the nut in the 3 jaw- Now you can unthread the 2-56 tap and drill and tap the new size. The ME series are a 40 thread standard, I think all the way from 1/8" to 3/8" diameter. They are particularly good for thread in boiler fittings and pipes. ron ginger ------- Date: Sat, 05 Jul 2003 16:15:55 -0000 From: "pvdawgman" Subject: Cutting 19TPI Threads? I have an Atlas 12x36 lathe and need to cut a BSP (British Standard Pipe) thread which has a pitch of .0526" (19TPI) but there is no 19 setting on the QC box. The part is to replace a missing grub screw on a KeeKlamp so it is nothing critical. Any ideas on how to go about cutting this thread besides carefully? I am open to any and all suggestions. Thanks in advance. ------- Date: Sat, 5 Jul 2003 15:38:59 -0400 (EDT) From: x xx Subject: Re: Cutting 19TPI Threads? Wild guess here - 19tpi implies about 1/4" diameter. Could you overbore and retap to a standard SAE like 5/16"? Sam ------- Date: Sat, 05 Jul 2003 15:40:15 -0500 From: Jon Elson Subject: Re: Cutting 19TPI Threads? Wow, this is a hard one! but, if you can beg or borrow some change gears, you can get close. There are several combinations. One that comes fairly close is to set the QC for 14 TPI, and put a 54/40 set of reduction gears in the train to slow down the leadscrew by 35%. 14 TPI = .0714286" per rev. .0714286 / (54/40) = .05291007, which is 18.89999 TPI. That should be pretty close. Jon ------- Date: Mon, 07 Jul 2003 02:43:57 -0000 From: "Damon" Subject: Re: Cutting 19TPI Threads? The QC box can be "shifted" by replacing the idler gears with a set providing reduction. If you happen to have (or can beg/borrow) some change gears, this shouldn't be too dreadful. If you implement a 64/20 gearset, and set the QC box at 6TPI, you'd end up cutting (6*64/20) or 19.2TPI. 54/20 and 7TPI gets you 18.9TPI. 64/54 and 16TPI gets you 18.96TPI. I think this is about the closest you can get using standard Atlas change gears. If you had to purchase or make new gears, then you can easily dial it dead on. HTH, Damon ------- Date: Mon, 07 Jul 2003 12:03:38 -0500 From: Jon Elson Subject: Re: 19TPI raises more questions pvdawgman wrote: >Thanks to all who responded to my original post on cutting 19TPI >threads using an Atlas 12x36 lathe with a QC box. I am aware of the >priciple of change gears but was not aware that my lathe has this >function as the manual never mentioned it. So the question is where >and how do I use this function? Have had this lathe for 25 years and >never ran into this problem as the QC met all my needs but now as I >get into oddball stuff it bubbles to the surface. Thanks again for >the help. In the meantime I will fake it by cutting three threads in >the middle of the engagement at 20TPI so I can get the project moving >forward. There is a bracket behind the QC box that is similar to the bracket that holds the change gears on lathes without QC. (It has fewer arms, however.) You loosen the T-handle and swing the arm away from the spindle gears. There will be at least two bolts with bushings and gears on them. You can remove the nuts and change the gears on the bushings, or add a new bolt and bushing if you really need to. Then, you swing the arm back up to engage with the spindle gears, and tighten the T handle. This mechanism is provided for exactly this purpose, cutting threads not available directly on the QC. Most QC lathes have this feature. Jon ------- Date: Mon, 7 Jul 2003 23:53:18 EDT From: anthrhodesx~xxaol.com Subject: Re: Cutting 19TPI Threads? In a message dated Sun, 6 Jul 2003 12:56:23 -0700, Bob Barker writes: << In your sugestion for cutting 19 threads per inch the '55' tooth gears should be 'SS' for steel spacer. This makes me wonder why all the gears that were supplied were even numbers. What would happen if there was a '55' tooth gear? Just curious. >> First, before discussing a 55 tooth gear, I *think* that if you had the following gears the following setup would cut 19 TPI: 20 driving gearbox, 38 & 36 on idler stud with 36 engaged with 20, 24 on another idler stud engaged with 38 and driven by 16 on the reverse tumbler, then engage 18 TPI on the gearbox. (This is based on general principles but details can modify the results and I haven't sat down with the exploded view of the gearbox to check this out.) Regarding the 55 tooth gear, you just have to factor its value into any gear train you set up. American lathes generally use change gears seperated by 4 teeth. British lathes often use change gears seperated by 5 teeth. If you take a typical by-4s set of gears and multiply each tooth count by 1.25 you'll wind up with relatively common values for a by-5s set. Vice versa, take the by-5s set and multiply each tooth count by .8 and you'll wind up with a fairly representative set of by-4s gears. There will be certain exceptions. 46 and 54 in the by-4s set, and 38, 21, and 63 in the by-5s set (which are special cases), won't readily convert to the other system. The big advantage to 5-tooth differences is it reduces the likelihood of setting up a gear train in which compounding would create interference between different gears in the train. One disadvantage to 5s relative to 4s is that, presuming the same DP or module, the gear trains occupy more space so you may run out of room to set them. An advantage of by-4s is the greater flexibility in gearing for 1/2 TPI values (ie 11-1/2). There are some lathes that use change gears by-3s which can provide for compact gear trains but don't have the benefits mentioned above for by-4s or by-5s. Anthony Berkeley, Calif. ------- Date: Sat, 26 Jul 2003 18:31:32 +0100 From: "Ernest Lear" Subject: Re: metric quick change gears? 127/ 50 tooth gears use in the train to cut metric threads do not need to be cut with the same tooth pitch as the standard gears supplied with the lathe. By using a finer pitched teeth on just these two grears, the O/A diameters. can be greatly reduced. The centre( bose) of each of these gears will be made the same as the standard gears use on the Atlas lathe. Both these gears when required will only need to mesh with each other. The 127T will be on same spindle with a standard pitch gear and the 50T on the lead screw.(these could be the other way round when you come to work out the overall train) This will give you the 25.4 to 1 ratio that you after to cut metric with the imperial 8T to 1" leadscrew fitted on a Atlas lathe. I leave it to you to work out the gear trains you will need for each metric thread and you can make up your own table of the gears required to cut any metric thread.It can be done. Ernest. ------- Date: Sat, 26 Jul 2003 16:53:55 -0700 From: "Bob May" Subject: Re: metric quick change gears? Since the 127 and 100 tooth gears are only going to mate with each other and no other gears, you can use any pitch you want to use and something a bit finer in pitch will do just fine. Remember that you aren't driving the carriage with any high power when doing threads so the finer pitch gears won't make as much of a problem with power transmission. I'd also suggest that you try to get some additional gears so that you can doe 10:1 and/or 5:1 ratio changes in the rest of the gear train. This will help in getting the rest of the thread sizes if you want to go for all of them. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Sun, 27 Jul 2003 00:40:54 EDT From: anthrhodesx~xxaol.com Subject: Re: metric quick change gears? lesleynwardx~xxyahoo.ca writes: << Yes, Mert and Charlie both, thanx, 21 x 6 being near enough 127. >> DO NOT MAKE THIS MISTAKE!!! When using a 127 it's used as a *driven* gear, when using a 21, 42, or 63 it's used as a *driver*. In the example of a gear train using a 127 and a 100 with an 8 tpi leadscrew, the 100 drives the 127 mounted on the leadscrew. This setup will cut a 2.5 mm pitch thread. In the example which was provided earlier using an 80 and a 63 with an 8 tpi leadscrew, the 63 drives the 80 mounted on the leadscrew. This setup will cut a 2.5003125 mm pitch thread, an error of 1-1/4 parts in 10,000. If you use the 21, 42, or 63 as a driven gear in place of the 127 your error will be almost 80 parts in 10,000 (1.0079365). Learn how the gear trains modify the effects of the mechanism and never trust somebody else's tables without confirming the math. Anthony Berkeley, Calif ------- Date: Sun, 27 Jul 2003 13:07:10 -0500 From: Jon Elson Subject: Re: Re: metric quick change gears? >Thanks, I appreciate your responses and discussions. I dont exactly >recall the particular metric thread I wanted to cut. On reviewing the >manual, the chart called for a steel spacer. I think that's what >initially put me off. Has anybody done the set up using the double- >keyway spacer? I guess I'll have to check Clausing to see if this >item is still available. If not, you can make it in a half hour. You cut a tube down so it won't interfere with the teeth of a gear that would mesh with a 20-tooth gear. In other words, its OD must be a little less than the minor diameter of a 20-tooth gear. The ID should be the same as the OD of the keyed bushings for the gears, not counting the keys. Cut it off to the same width as the hubs of the standard gears. Then, file slots to clear the keys on the bushings. This thing doesn't need to be accurate at all, just a spacer to hold one gear securely on a bushing. Jon ------- Date: Sun, 27 Jul 2003 14:19:26 -0400 (EDT) From: x xx Subject: Re: Re: metric quick change gears? Yo, Jon, and here is a really dirty, if not quick, work around: Stack up a buncha 1.2" washers till you get required thickness. A flat file on edge will cut the slots to accommodate the double keyed bushing in no time at all. Sam ------- Date: Sun, 27 Jul 2003 18:24:43 -0400 (EDT) From: x xx Subject: Re: Re: metric quick change gears? If the other guys don't pick me up on this, you can just go ahead and do it: I think you have an Atlas with an 8 pitch lead screw. Look at the gear on the end of your spindle.Best if it is a multiple of 8 (because the lead screw is 8). Doesn't absolutely have to be, but if it is, the calculations become easier. This geat meshes with one of two dinky little gears that move in and out of mesh when you move the tumbler lever. The depth of mesh is set at the factory, so you can't bugger the gears by setting them too tight or too loose. However - Achtung, acthung - You not only can, you will bugger these gears if you shift the tumbler while the spindle is turning. Fundamental rule number 1: don't mess with a rotating spindle! On the end of the Lead Screw there will be a gear that can be taken off the leadscrew. It is capable of turning the LS because it has a little square notch (two actually, tho' you only use the one) in the side of the bore. There is a matching notch in the end of the leadscrew. These notches are called "key ways" and a little square sectioned piece of steel, the key, straddles the notches so the wheel can't turn on the LS when the key is in place. The whole shebang is held in place by a washer wide enough to cover the outboard end of the keyways, so the key can't slip out. The washer is held in place by a screw tapped into the end of the LS. No rocket science here. The position of the LS is fixed in the machine so there are no immediate depth of mesh issues here. A device called a banjo is clamped around the outside if the boss that the LS runs through. If yours is ZAMAC, (there is that ugly word again!), don't diddle around with the clamp screw while the banjo is off the boss. It will break, and making a new one is a pain. On the banjo you'll find three studs that are actually square headed bolts whose heads run in groves on the inside of the banjo. These studs are nifty, with shoulders at the right place when you get them new. If you don't have nifty ones, fake them up by using bolts (don't remember the diameter off hand), slipped through bits of steel tubing of the right diameter just long enough to give you a fake shoulder when you take up the nut on the bolt. You use one two or three of these studs depending on circumstances and they can slide along the slots in the banjo to permit adjustment for wheel size and proper mesh. No rocket science here either. The way you get proper, or at least acceptable, mesh that won't bugger your gears is to rip a little strip of paper off the edge of an 8 1/2 x 11 sheet of bond. Stick the strip between the gears you are bringing into mesh, clamp down the stud, and pull out the strip of paper. Bingo - workable mesh! I stick a bit of engine assembly grease on the wheels while I'm in there. There are better kinds of grease, lubrication-wise - but I like Assy grease because it's white and easy to clean off again. As for clamping down, the important thing is that the gears and their bushings can revolve freely on the studs, without having a lot of end play. The big thing here is to use the strip of paper. Obviously before you flip the switch you turn the setup by hand to make sure everything turns freely. It'll tell you at this point if it's unhappy. We've already talked about the famous spacer just being a gear wheel without teeth. So just use a wheel that can't reach into mesh with anything it shouldn't mesh with! Hope that helps. Sam ------- Date: Thu, 31 Jul 2003 18:16:59 -0400 (EDT) From: x xx Subject: Re: skimming acme for fit Damon Gentile wrote: >>> I was thinking a bit about the discussion a couple weeks ago about skimming an acme thread when turning a nut to fit. Ok no problem with the skimming cut, seems easy enough. Just to trim the sides of the thread. Chuck in the new nut-to-be, bore it out, and start to cut the internal thread. A few passes and a little sweating, and it's at depth. Trial fitting now shows that the thread fits into the nut. BUT--- if the skimming operation shaves a couple of thou from the thread (crossfeed screw here) would it be undersize enough to be a sloppy fit in the nut? (Nut is cut to *depth* but the feed screw was cut to width.) Is this just a complete triviality here ?? The one idea I had would be to cut the grind the thread boring tool to a sharper point. Still 29deg but a smaller flat on the end. This way the depth doesn't matter, I can just keep advancing the compound until there is a perfect fit between the two. Sound good, or did I just completely go wayyyy overboard ? TIA, Damon <<< Hi Damon. I was still lying in my basket, growling, when yer post popped up. I thunk about what y're suggesting, and I don't see why the geometry couldn't be got right. 'Course what you'd have at the end wouldn't be an Acme thread at all. But that's okay, we can just call the new standard the "Gentile Phred". If you sit down with a grid pad and sketch out the section of the helix of male and female phred at each stage of what you are suggesting, I think you'll see that you'll wind up with lotsa slop, unless you'll accept a skinny helix on the LS and a phat helix in the nut. Do the sketching at scale of a square to five thou. I wouldn't be surprised that Mr. Acme, when he designed his Phred, had gear wheels in mind and imagined a pitch diameter, or at least a pitch line, such that addendum and dedendum were equal, i.e. the imaginary pitch line is at {D(max) + D(min)]/2 on the genoowine article. Bet that is part of the standard. The Gentile Phred would have the pitch line positioned otherwise - lower on the male, higher on the female. No reason it can't work, since the section of the "teeth" is rectilinear, rather than involute. And you'd be able to claim without blushing that yer lathe is truly unique! Regards Sam ------- Date: Thu, 31 Jul 2003 18:29:40 EDT From: n8as1x~xxaol.com Subject: Re: skimming acme for fit ur close to the solution ..........cut the acme nut w/ an undersize tool bit ( 10 to 20 % ) to CORRECT depth w/ compound set in line w/ spindle ...then take side cuts of a few ,down to .001 ,testing for fit ( & making ur thrd" Beautiful",...could even use a side tool .)......this was the olde tyme way of cutting a square thrd when componds didnt exist & hogging straight in , even w/ gooseneck tool left serious roughness ,removed by side finishing to fit ..This was almost mandatory w/ really coarse thrds,..even in U S A ,we used roughers to hog out the thrd...method came across the pond from england, but seemed to mostly stall out in canada....added bonus ,u dont have to grind an EXACT bit ...just get the slope/slopes dead nuts best wishes docn8as PS ...wholesale tool has 1/2x10 acme taps for $18 . other sizes ,as cheap .....its getting so stuff is so cheap , one has to be really pigheaded to fab it urself wholesale tool has 6 in rotary table for $99 , 4 in $73 ???....yeah ! go make ur own!!!!!!!!!!( makes me feel stupid making my own taps reamer s,cutters etc. , but he--, thats what i LIKE.to do !!!.)...........course ,if u non spec. the thrd , better do same w/nut! ------- Date: Thu, 31 Jul 2003 19:19:28 -0400 From: "piggy" Subject: Re: skimming acme for fit methinks tis far easier to just cut the thread as it was intended to be cut, course i been wrong plenty ! Don T. EVO Power & Machine www.accessatc.net/~piggy www.snartracing.com ------- Date: Fri, 01 Aug 2003 00:50:51 -0000 From: "Damon" Subject: Re: skimming acme for fit Ah I gotcha. Grind to a smaller tip, keep the angle. Cut to depth. And now I've got the proper profile, but fat teeth remaining. Swing compound around to dead on, pick up the thread, and give it some real small shaves until the leadscrew glides right in there. Perfect, makes plenty sense, thanks Doc! Taps are cheap. I betcha new nuts from Atlas aren't even that expensive. But I'd rather learn the way that will always work, no matter how silly the thread may be in the future. Especially this skimming method, seems like a pretty good way to restore truth to the whole setup. Just tapping a new slug of brass, I'd be forced to have slop in the middle so it wouldn't bind on the ends. Imma learn the hard way, and probably ask a couple questions doing it, to !! Sam, the mateup would be just as designed by Joe Acme, with the exception of an "helical oil groove" (patent pending) cut into the thread in the nut. You mean to tell me when you cut a 60 degree thread, you stone off the point to cut the flat at the root of the thread? Still will register accurately on the ID of the bore/root of the leadscrew thread. Angles would stay at 29 deg, locations may move a few thou. ?? Just kickin' some ideas around. Thanks, Damon ------- Date: Thu, 31 Jul 2003 23:07:16 -0500 From: Jon Elson Subject: Re: Re: skimming acme for fit >Ah I gotcha. Grind to a smaller tip, keep the angle. Cut to.... Yes, I made a crossfeed screw and thread this way, and it turned out great. (Of course, I cut it Right hand, and then discovered to my horror that the crossfeed screws are left hand!) Jon ------- Date: Thu, 31 Jul 2003 21:31:49 -0700 From: "Gregory Bowne" Subject: Re: Re: skimming acme for fit Well, This has me thinking.. I have been known to use carbide indexable threading inserts with their special toolholders for this purpose for creating the standard ACME threads I've had to replicate. And, I notice as I look through my insert assortment I have the 8tpi ACME type in Left Hand. Though after I bought a new backplate and chuck my ACME threads have been much cleaner than the 29 deg. Std. I do all the time. My total runout since has been in the order of .0002 and maybe .0003" on the occasion. Greg ------------------------------ Date: Thu, 24 Jul 2003 20:51:49 -0700 From: "keith green" Subject: Re: How to remove broken tap/drill [sherline] Original Message --- From: captain_est Sent: Thursday, July 24, 2003 5:31 PM I have been trying to tap some 2-56 holes in aluminum. Unfortunately, I broke a drill and a tap. Is there any way to fix this problem? When I look at some of the projects that I want to attack, I can see the potential to break many drills and taps. There must be a way to solve this problem, or, later, to prevent them, but I am new to metalworking. When we break a tap at work and can't get it out, we use a guy who has an EDM machine to get it out. Prices vary but we pay very little (comparatively)...maybe between $20 and $40 Can. per hole or so. keith vancouver, bc ------- Date: Thu, 24 Jul 2003 20:21:00 -0700 From: "Dave Hylands" Subject: RE: How to remove broken tap/drill Hi, You can remove taps from aluminum by using nitric acid. http://yarchive.net/metal/tap_remove.html http://www.ytmag.com/articles/artint62.htm Obviously, you need to be VERY careful handling this stuff (if you can find it someplace). Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Fri, 25 Jul 2003 02:46:17 -0400 From: Jim Ash Subject: Re: How to remove broken tap/drill I haven't tried this with anything as small as a 2-56, but I have done it with a 4-40: If the tap is a 2-flute, ram two pieces of music wire (or sewing needles) down the sides of the tap and grab them tightly with a pair of pliers near the base of the hole, and turn. Unfortunately, this doesn't work with 4-flutes, because the flutes are too small, but chances are, with a tap this small, it's a 2-flute anyhow. Of course, this won't work with a twist drill because the flutes aren't straight. Ther is a gadget called a disintegrator which can electrically burn the tap/drill out, but it ain't a cheap date. If you have a local machine shop that does EDM, you might get their help. Scrapping the part and starting over might be cheaper, depending on the part. For the future, especially with small taps like this: 1. Always use a guided setup, preferably in a lathe or mill. A tap stand will work but make sure the piece is clamped down somehow. 2. Take whatever standard you use for breaking chips (a turn, two turns, ...) and cut it in half for small taps; even less if it's one of those 'sticky' metals like aluminum or copper. If you go until you feel it stiffen up, you might be too late. Better to tap it slowy that to have to deal with this problem. Been there, done that. 3. Instead of just breaking the chip each time, remove the tap completely every few breaks and flush out the hole. If it's a blind hole, use a small syringe to flush from the bottom of the hole upward. Good luck. Jim Ash ------- Date: Fri, 25 Jul 2003 07:38:26 -0400 From: "Marshall Pharoah" Subject: RE: How to remove broken tap/drill A couple of tips for the future: 1. Be sure to use a tapping fluid rated for aluminum. 2. Use a good grade of aluminum. Some does not machine well. 3. You may be able to drill the hole slightly larger depending on the strength you need. Most charts show the drills for a certain percentage of thread engagement. Some charts show for two or three percentages. A larger hole means less tapping force (as well as less strength). 4. Use at least a tapping block as a guide. 5. For a 2-56, use a tap handle with shorter handles, maybe around 4". Less leverage means better feel of the forces involved. 6. A thread forming tap is more expensive, but needs no flutes for clearing the chips so it is stronger. The drill size differs from normal. When drilling holes this small, use a sensitive drilling attachment rather than using the mill or a normal drill press, or perhaps "peck" drilling might work. At any rate, you will need to stop and clear the chips often. Marshall ------- Date: Fri, 25 Jul 2003 15:54:33 -0400 From: Jim Ash Subject: Re: How to remove broken tap/drill A slightly more radical method is to grind / cut away the material around the hole down to where you can grab the tap, then fill in the hole with a tig welder, redrill, and try again. Depending on how much tap was broken and how much hole/thread is under the weld, this method may not work for you. Jim Ash ------- Date: Fri, 25 Jul 2003 14:56:51 -0500 From: "Ron Thompson" Subject: Re: Re: How to remove broken tap/drill If you are going that far, drill it out with a small hole saw, then weld it up. I have seen center drills removed by grinding larger broken center drills so they resemble little fly cutters and just remove the metal around the broken center drill. The least damaging to the part is the nitric acid. It will remove the steel and leave the aluminum relatively untouched, unless left too long. Ron Thompson On the Beautiful Mississippi Gulf Coast USA ------- Date: Fri, 25 Jul 2003 02:51:46 -0000 From: "Charles Hixon" Subject: Re: How to remove broken tap/drill TIA, in aluminum, depending on the part, my tolerance and who I'm trying to impress, I sometimes counterbore the backside just small enough diameter so that I can embed a steel nut to use for my thread. That's not appropriate in some applications. Charles Hixon ------- Date: Sat, 26 Jul 2003 08:39:11 +1200 From: "Richard T. Perry" Subject: Tapping Jim - recently, you posted quite a nice message about tapping. Part of it, though, I found really interesting: >3. Instead of just breaking the chip each time, remove the tap completely >every few breaks and flush out the hole. If it's a blind hole, use a small >syringe to flush from the bottom of the hole upward. I did my initial mechanical training courtesy of the US Navy (I was an MM2(SS) - retired, now), and one of the things I remember clearly was that I was told that you never remove a tap from a hole or a die from a rod completely until the entire operation is done. Sure, back it off signifigantly - no problem, but the guy who taught me that said that it resulted in a much "cleaner" thread that way - I think he was concerned about crossthreading. So that's what I've done over the years (with the exception of changing tools and "oopsies", obviously.) Perhaps he was just trying to keep us FNG's (or NUB's, if you prefer) out of trouble until we had enough experience to "feel" the threads under the tap, but I would think that caution applies double for small taps - it's a lot harder to me to feel 80 pitch then it is 1/4-20, say. So what does the collective say - do you take the tap out, or leave it in? Regards, Richard T. Perry ------ Date: Fri, 25 Jul 2003 17:15:39 -0400 From: Jim Ash Subject: Re: Tapping To tell you the truth, I don't like it either. I don't like running material the wrong way past a cutting edge to back one out. It can ruin the surface you just cut, as you say, and possibly the tool, too. This is why reversing a reamer is a strict no-no, but there's no reason to do it anyhow. But if I'm tapping a small thread in a deep hole in nasty material, that's a compromise I make. My responses to this thread were based on the memory of having to tap a set of blind holes 3/4" deep with a 4-40 in pure copper. There's no way I could have ever completed that job without removing the tap; the chips would have plugged up the operation. For me, it's one of those touchy-feely things. And I pay real close attention to my re-starts so I don't booger up the existing thread. Dies are a different story, because the operation is exposed and can be cleaned more easily. I've never felt the need to remove one before the threading operation was completed. Given the option, I'll run a die off the other end if I can, rather than trying to back it off. I'd like to hear the other opinions, too. Jim ------- Date: Sat, 26 Jul 2003 16:38:37 EDT From: snookdustx~xxaol.com Subject: 0-80 crankpin screws Hello Guys and Gals-I'm new to the list but have been using the Sherline mill & lathe for a while now. I've been making up some 0-80 hex-head crank pin screws for model railroad projects.I've been using 1/8 brass rod in the 3 jaw chuck and turning it to .062 the right length then while it was still in the chuck threading it for 0-80 ,then using the cut-off tool and then cutting the 6 sides in the rotary chuck in the mill.I,m planning on getting the 1/8 ww collet so I can use longer lengths of rod.Is this the right sequence or any comments? no machine shops in this area so we have to guess at lots of things Bob V ------- Date: Sun, 27 Jul 2003 14:54:38 -0000 From: "n2562001" Subject: Re: 0-80 crankpin screws Bob, I have done 100`s of bolts like this for years down to .009".I do it slightly different when I need several of one size. I will cut several pieces of stock about an inch or so long. I will then cut the body of the bolt and thread it on each end. A reverse switch and the use of collets saves a lot of time when threading on the lathe. From that point the pieces are transferred to a collet in the indexer for the hex to be cut. ( held by the stock ) When the hex is cut it is cut long enough so that when the bolt is cut off there is enough left over for a nut or two. If accuracy is absolutely critical you can hold by the tread in a collet without damage. It`s a pain in the butt but there`s no other practical way to do it if you want what you want. Jerry Kieffer ------- Date: Sun, 27 Jul 2003 11:38:18 -0500 From: "Ron Thompson" Subject: Re: Re: 0-80 crankpin screws This is a good order of operations. I do have one hint that I ran across. Threads can be held without damage in a split nut. Just a saw cut on one side that will let the nut close on the threads when held in a 3 jaw chuck. Ron Thompson On the Beautiful Mississippi Gulf Coast, USA http://www.plansandprojects.com ------- Date: Sun, 27 Jul 2003 09:55:43 -0700 From: "keith green" Subject: Re: Re: 0-80 crankpin screws I had to make a buttload of brass screws on our cnc machine a few months back. I made a split collet threaded on the inside to hold the screws for parting off and milling the hex. Used a piece of cold-rolled hex, drilled and tapped to the required size, put a round groove on one end, then sawed lengthwise into 3 pieces. The groove was used to receive an o-ring which held the pieces together when out of the chuck. keith ------- Date: Thu, 14 Aug 2003 12:36:06 -0000 From: "tnance0913" Subject: HSS vs Carbon Steel Dies Greetings Threadcutters, I found while looking thru the MSC catalog that there are two varieties of dies (as well as taps). There are dies made from Carbon Steel and dies made from High Speed Steel. A 39-piece set of Hansen Carbon Steel dies cost $103.47 while the same set in HSS cost a whopping $437.86. Years ago, a member on this list said that if you want to have any success in cutting threads you must start with a high quality tool. My set of Craftsman taps and dies has served me pretty well over the years, but the results from them are getting sorta sloppy now and I think it's time they were replaced. My question is: if the cost of HSS is four times that of carbon steel, is the quality and durability of HSS four times better than that of Carbon Steel? I almost always work in the range of 2-56 thru 1/4-20 and mostly build in aluminum, brass, and mild steel. All of that is pretty soft stuff, so I'm not going to really overstress the taps and dies. So should I get the HSS, or will the carbon steel set produce the same result with the same effort? There are also several manufacturers of taps and dies listed. They are, Hansen, Greenfield, and Cleveland. I know they probably all have their manufacturing done overseas, but does anyone have an opinion of one having a higher quality product over another? Thanks, Tom Nance Corpus Christi, TX ------- Date: Thu, 14 Aug 2003 12:40:55 -0000 From: "kevin_sedota" Subject: Re: HSS vs Carbon Steel Dies I was going to the local hardware store to get my taps but they would break on a fairly regular basis. So I asked my gunsmith who he thought made the best taps. He said OSG. Since I've been getting these I haven't broken one. They are extremely sharp. They do cost a bit more but in my opinon they are worth it. J&L usually has some on sale. They come in a fairly wide range of coatings and shapes. ------- Date: Thu, 21 Aug 2003 17:17:32 -0000 From: "Glen Reeser" Subject: Re: Helicol thread ? --- In sherlinex~xxyahoogroups.com, "keith green" wrote: >> I'm guessing the focussing mechanism in your lens uses a multistart thread (fine pitch, quick movement). On a normal lathe with a threading dial, it's a snap. On a Sherline???? Anyone? keith.<< When I was using my Sherline to cut multi-start threads, I would finish one thread and then loosen the gear train so I could turn the spindle 60 degrees and then tighten it back down. The spindle gear is 100 teeth. I counted each 33 teeth and put a mark on the gear. The last one was 34 teeth, close enough for what I was doing. I now do this job on my South Bend. I just advance the compound slide by 1/3 of the pitch to cut the next lead. It is much easier this way. Glen Reeser ------- Date: Thu, 16 Oct 2003 20:52:24 EDT From: catboat15x~xxaol.com Subject: Re: Center Gauge Question > I have no idea what "Double Depth of thread" means and how it is used. Double depth of thread is the measurment of the "core" or what you have to subtract from the OD to find the ID of the thread. For example on the 10 TPI measurment it gives .130 for the double depth. So for a 1 inch 10 TPI the runout groove should be 1 minus the 0.130 diameter. Now for the interesting part, some lathes have the cross slide or compound graduated in the depth of cut, some have graduations that give the difference in DIAM for any cut. I.E. on my Atlas at least the marks are for depth of cut or the size of the chip. So if I advance the dial 1 graduation the cut will be 1/1000 deep but the stock will be reduced 2/1000 in diameter. My reference for the Atlas in their book has tables for not only double depth, but single depth and a set of columns for the distance to advance the compound if it is set at 29-1/2 degrees. Plus tables for full V form with sharp bottoms and tops of the threads and for the better practice of leaving a small flat on both top and bottom. The advantage of single point thread cutting on the lathe is that you know the threads are really parallel to the stock material. Some times a tap or die will be started a bit crockeyed and produce a "drunk thread". John in the high desert of California 12 inch Atlas Mini Mill New email address is k6sufx~xxdirecway.com ------- Date: Tue, 21 Oct 2003 19:46:31 -0400 From: Daniel Munoz Subject: interrupted-screw Hi guys, I need a small bolt+nut that look like that, for a miniature model I have in mind: http://www3.sympatico.ca/dm666/5b10.jpg Maybe some of you will recognize a schematic describing the breech closing mechanism of an old naval gun. The screw diameter would need to be about 3/8". I don't think I'm lucky enough to find a ready made nuts+bolt, so would you have some suggestion about how to machine such a thing (in brass) ? I though about using some small files, but there's very little chance it would be good looking :-) I was thinking maybe gluing some thread sections into the hole and around the rod (it don't need to be very sturdy). Any other suggestions ? Thanks in advance. Daniel http://www.nutsnbits.com ------- Date: Tue, 21 Oct 2003 20:07:46 EDT From: wanlikerx~xxaol.com Subject: Re: interrupted-screw Cut the two threads in full thread form, set them up one at a time so they are indexed, and use the topslide as a hand shaper, will take some thought to make them come out properly indexed to each other, Thread them together, and mark the area to be removed, on each piece, good luck, but it will work bill ------- Date: Tue, 21 Oct 2003 20:09:18 -0400 From: RichD Subject: Re: interrupted-screw Dan, easy to do on a milling machine. Run an endmill along the threads of the screw for the recess, index to the next spot, do it again. In the nut, plunge the end mill to create a matching recess. Using stock screws/nuts eliminates making the thread. RichD ------- Date: Wed, 22 Oct 2003 00:00:38 -0400 From: RichD Subject: Re: Re: interrupted-screw > I would prefer to mimic the sharp edges between the flat and the thraded > part. A end mill would give a rounded cut. Dan, On the screw, an endmill with axis at right angles to the screw, it will machine a flat. In the nut, a special made bushing and a keyway cutter (broach) pushed thru will make the flats as well. RichD ------- Date: Wed, 22 Oct 2003 01:13:34 -0000 From: "jmorrphd2" Subject: Re: interrupted-screw Dan: Does this have to be monolithic? Can you have pieces soldered together? Is the thread tapered or straight? How many pieces like this will you need? The nut is by itself or part of a barrel as a solid piece? Do you need right angle cuts or radial cuts on the sides of both threads or can you have radiused cuts on the female portions of the threads? I would put the nut in an indexer after the full threads are cut and then just use a small tool to cut notches on it using a shaper or you could do this on a lathe with the headstock locked. After rotating back 90 degrees, just start a deeper cut. If you needed many pieces, you could make your own broach. I bet in real life, these things were tapered. Have you checked the patent literature? Jim ------- Date: Wed, 22 Oct 2003 09:25:21 -0700 From: Alan Marconett KM6VV Subject: Re: interrupted-screw I think you could simply MILL the interruptions. Your pic has a pair of interruptions, which can be milled on the bolt quite simply by an end cutter, removing two 90 degree regions. Similar for the internal thread. Remove enough (a little over 90 degrees) so that the bolt can be rotated and removed. A rotary table would be useful for both operations, however an index disk could be prepared to perform this task, as the accuracy requirement is not high. Alan KM6VV ------- Date: Thu, 30 Oct 2003 04:17:10 -0000 From: "John Bentley" Subject: Cutting all kinds threads on the Taig [AND OTHER LATHES WITHOUT CHANGE GEARS] You can cut almost any thread if you have a small bolt of that pitch. I use a homemade attachment which can copy that number of threads into any form and any diameter. It's not fast, it's not easy and it's certainly no Frog, but it will work well even with very coarse pitches. Tom's method of using taps and dies makes a lot of sense for most small work, because it's fast and the diameter and form are looked after pretty well automatically. However, large diameters are not possible with this method. My two cents, John ------- Date: Fri, 31 Oct 2003 05:10:51 -0000 From: "John Bentley" Subject: Re: Cutting all kinds of threads on the Taig > Your attachment sounds very interesting. Any more information, plans > or pictures that you can share would be appreciated! My threadcutting attachment is based on the same type of method that used to be used on the older Unimats. Essentially, it consists of a large rod above and behind the lathe, sliding in bushings held by supports on the headstock and tailstock. The rod has an adjustable cutting arm with toolholder, which drops down on the revolving workpiece, and a spring-loaded follower arm which engages a sample of the required pitch to the left of the spindle pulley. This can be either a prepared thread form, or a piece of bolt etc. held in the drill chuck and attached to an expanding mandrel in the spindle hole. The contraption can reproduce the pitch and direction (LH or RH) of the original onto any reasonable diameter. The form of the original doesn't affect the outcome - Acme, square, buttress, Metric, UNC or F can all be cut using a cheap hardware-store bolt. It can do either inside or outside threading from the same original male form. I am not claiming my device is refined, as I worked out the geometry by much guesswork, and someone could easily improve that aspect. The rigidity of the cutting arm could also be beefed up - I made the thing in the early days of my hobby and bolted keystock together for a lot of the construction, due to lack of other materials, equipment and experience. It requires careful work to make nicely matching threads with this device, but the same is true with any threadcutting lathe. I don't find it any more difficult to use than the standard-type changewheel system on an Asian mini lathe - just a whole lot different. It feels more like woodturning. I set three experimental goals for myself when I started to make the device: -First, I wanted to be able to make a coarse thread (8 or 10 tpi) in both LH and RH. -The second was to produce a threaded filter ring for the front of an SLR camera's lens -My last wish was to thread a backplate cover, and put a matching thread inside the crankcase of a 1/2A-sized model glow engine. All my goals were achieved. I made a 49mm filter ring for my SLR camera from steel, there's no glass in it, but it spins onto the front of the lens as smooth as silk. I also constructed the little glow engine - and it ran fine. As far as I was concerned, I had solved the only major shortcoming of the Taig, at least for my own future work. I have quite a lot about the details on file. I also have a front- view and an end-view drawing of the cutting arm, and a fair number of pictures. I could post some pictures, but a few of them need to be viewed fairly large. If you have a high speed connection, I could email you any or all of this stuff, to avoid boring the rest of the group. 'Meantime, I'll stick on a side view and end view of my lathe as well as a shot of the cutting arm. They are in the "photos" section, under "theengineman". I suspect they might need some explanation. I apologize for my web site being down "due to heavy volume of traffic" - it automatically resets on the 4th day of each month. John ------- Date: Sat, 01 Nov 2003 00:56:31 -0000 From: "John Bentley" Subject: Re: Cutting all kinds of threads on the Taig > Could you repeat the address of your website please? > This sounds like a great idea. Barry B Hi Barry: The site is www.JRBentley.com and should be back on line at Midnight on Monday, California (Pacific) time. I am sorting through my past emails now on the subject of the threader to try to put together a more comprehensive (and hopefully coherent) description of the threading attachment. Also I will try to round up a few more pictures to add to the first three that I have posted here with the Taigtools group. I should mention that I didn't invent this system of threading, but I designed mine to fit the Taig - the system had been in use for ages. I made my attachment years ago, and it was sufficient to do the type of threading that taps & dies can't handle, so I didn't bother refining my design. I would think a few very simple improvements could make quite a difference. This system requires very slow spindle speeds, especially near the end of the job. A good motor speed control on the lathe is nearly necessary. Since I don't have one, and my lathe will only go down to about 500 rpm, I have been pulling the chuck over by hand when nearing the end of the job to smooth the final thread finish. The tip of the threaded depth control rod is smoothly rounded and in operation is pressed against a metal plate covering the cross slide. On a long job, the carriage would need to be advanced now and again to keep up with the action. In practice, this is no big deal. My website consists of many pictures and brief descriptions of things that I have made with the Taig - it was even used to make improvements and attachments for an Asian mini lathe. However, there has been no recent changes to the "Workshop" page recently - that's coming. John ------- Date: Wed, 05 Nov 2003 00:37:29 -0000 From: "tonyryue" Subject: Can't get enough of those ball handles John, First off I want to thank you for the inspiration. I got a taig lathe about a year ago based in part upon your web site and an email response to some of my questions. I'm sorry to be so thick, but how did you put the bend in your replacement handles? I've found 9/16 balls for the handles at Lee Valley and I'm about to give it a go. Secondly, I'd love to put myself down as an interested party with regards to the leadscrew/threading attachment info. It looks great! Thanks again to all who contribute to the group; I've really learned lots from the interesting reading. Tony ------- Date: Wed, 05 Nov 2003 01:45:43 -0000 From: "John Bentley" Subject: Re: Can't get enough of those ball handles Hi Tony, The ball handle shafts were turned, tapered as they appear, but if you are going by eye, they need to be a little longer than you think is right. This is simply because more length is used up in the bend than you may expect. I put the threaded shaft end of the handle in a bench vise and heated the thinnest part with a propane torch turned down. At the same time, I put a light pressure on the handle with any convenient tool and waited for the shaft to bend. Very little pressure is needed and it doesn't need to be screeming red hot,either. Excessive heat or pressure might cause you to weaken the handle too much to be useful. Don't worry about which direction to bend the handle with reference to the thread orientation. The final position of the handle when screwed in can be easily changed. The toolpost handle can be set in one of four positions, depending upon which way the nut is oriented in the T-slot. Any of the handles will fit in the 3-jaw chuck after they are bent, to allow turning the hub shorter to control the "snugged-up" position. I think you mentioned you have read my last post about using ordinary used ball bearings from motors. Thank you for your encouragement and good luck. John ------- Date: Thu, 27 Nov 2003 13:53:01 EST From: n8as1x~xxaol.com Subject: Re: threadng [ATLAS_CRAFTSMAN GROUP] In a message dated 11/27/2003 jobarden422x~xxmsn.com writes: >I don't know if it will help, but I saw a picture of an 1" 1/2 thread being >cut on a lathe using a tap and using just the thread profile to cut the >thread and adjusting the crosslide a little every time for a deeper cut, I >dont think I explained it very well but it might help you out if you have a >tap of the same pitch. Jo have made life easier several times using a tap as a thread chaser , but always in small sizes where couldnt hardly get a threading tool IN!!!!.......worked great ....cleaner threads FWIW ...finally trashed the 1/2 nuts on crftsm12x36 turning & rethreading to a size smaller , a dozen john deere bolts.for neighbor ..it was well due & expected ! ,but it is upsetting to watch carriage moving in stop/go jerks while thrdng!!!!......after scotts post about thrdng at 700 rpm ,i did abt 4 at circa 680rpm ......can do , & it does hold ones attention !!!.. u do not get bored! but started flubbing after 4 ,(a loose belt is a wonderful thing , a gear head has no mercy in its soul )so dropped down to circa 266 (which now seemed slow ,& breathed easier ......truth was , i first thot he was joking so decided to see!......., after crftsmn 1/2nuts trashed, finished thrdng on 1895 reed ..14 in. w/ gooseneck thrd tool feeding straight in since it was built sans compound ( side dovetail one i am building still needs feed screw,,only been a year.)......put on my shop built thread stop to keep track of where i was w/ cross feed dial( an add on ) & it was more than a bit of a pain ......old timer told me he used a grease pencil to make a mark on dial after each added feed /cut...think i wasted time making thrd stop & maybe making a compound ,since w/ gooseneck tools, I can point up centers w/ a 3/8 flat w/out chatter..& it has a taper attach..any way , the point is ..the thrds were cleaner straight in w/ gooseneck than w/ compound at 30 deg. w/ crftsmn , using heavier cuts........course lathe weighs 1800 lbs.& thrd pitch was only a 20.but think the flex of gooseneck holder is the answer ....maybe i am not the only one using antiques & someone wll get some use out of this post gobble .gobble best wishes docn8as ------- Date: Thu, 27 Nov 2003 13:00:03 -0600 From: "Richard Meredith" Subject: Re: Big Metric Die Using a tap as a threading tool can be done, but you would still need the lead screw to advance the tap with the cut. A stationary tap will only cut annular grooves. Many insert type commercial threading tools have multiple thread profiles (or pitches). ------- Date: Thu, 27 Nov 2003 14:05:40 EST From: LouD31M066x~xxaol.com Subject: Re: Big Metric Die Making vs buying problem...unless you chance upon a flea market find...the choice is between rare, hard to find and expensive if you can locate AND getting brave enough to set up gears for a metric approximation, grinding metric thread profile on single point and having at it. May take more than one try to get it right, but, next time you will KNOW. Or so it seems to me...I have limited experience so I am not a know it all...but I do know that cutting threads is one of the things a lathe is good for...also boring, turning, facing, and many other things that require only imagination and determination. I have found the following rule helpful when considering a course of action: "What is worst thing that can happen? Can I live with a worst case outcome? If so, have at it!" Good Luck! Louis ------- Date: Wed, 3 Dec 2003 23:55:43 -0500 From: "Randy & Zonya Ledyard" Subject: RE: Re:Upgrade crosslide >brings up yet another question - how do you make a left-handed split >nut? I've searched for left-hand taps, and really haven't seen any. I bought a 1/4-20 LH threaded rod and LH 1/4-20 tap at McMaster-Carr (www.mcmaster.com) Randy ------- Date: Thu, 04 Dec 2003 01:38:42 -0000 From: "John Bentley" Subject: Re:Upgrade crosslide Vlad, some leadscrews are left-hand threads and some are right. Sherlines use left, for example and Asian mini lathes use right-hand threads (at least mine does). I bought a 1/4" x 20 Left Hand tap from WT Tools in Stoughton, MA some time back - they listed a fair few in their catalog. I wanted to have that tap on hand, as it matches the Taig cross slide nut. Some people seem to have no problem working out gear ratios for thread pitches. I have read all kinds of articles about taking the mystery out of it, and they just made me more confused. For me, that kind of arithmetic just does not come naturally! That's one reason why I elected to use the old Unimat follower system of threadcutting on my Taig, instead of gears. I don't find it any harder than using gears. However it is not that often I need to cut a thread that taps and dies can't handle. (of course large diameter threads are an exception.) John ------- Date: Fri, 5 Dec 2003 07:59:34 -0800 From: "Brown, Mark A (SPO)" Subject: RE: Tapping on the Sherline Lathe [OR OTHER LATHES] There are many tapping jigs available and although you mentioned you don't have the time to build one here is one I made early on that is very functional for what your doing and very simple to make. I got the idea/plans from somewhere but don't recall where (might have been the sherline tips section). It's pretty easy so I'll go over it quickly. Face a piece of round that is about 1.5 to 2" in diameter. Center drill it at about .175" about 3/8" deep then part it about 1/4" to 3/8" thick so you now have a wafer with a hole in it. Put it in the mill vise and drill and tap from the outside diameter to the inside diameter (perpendicular to the inside hole. Now just put in a set screw. You can knurl it if you like but I didn't and it works just fine. So, now you should have something that looks like a very big washer with a set screw in it that goes from the outside diameter to the inside diameter. Now to use it you just put any tap in it and tighten the set screw leaving enough to hold in a drill chuck. To use it in the lathe you put a drill chuck in the tailstock and put the tap in the chuck just loose enough that the chuck isn't actually holding the tap but keeping it centered and straight. Now your hold the tap holder with one hand while turning the headstock/material with the other. It keeps the tap straight and on center and pulls it into the work as it taps it. To use it in the mill mount the tap in a drill chuck (loosely again)in the headstock. Then lower it and turn the tap fixture by hand. Again, it keeps it straight and pulls the tap into the work. For those who have broken very small taps this works very well because it keeps the tap straight and prevents you from exerting lateral pressure on the tap causing it to break. Mark A. Brown "This project is so important we can't let things that are more important interfere with it." ------- Date: Fri, 5 Dec 2003 09:43:39 -0600 From: "Nance, Tom" Subject: RE: Tapping on the Sherline Lathe The easiest thing to do is to use the same Jacobs chuck in the tailstock that you used to drill the hole. Just chuck up the tap, loosen the chuck from the tailstock (don't remove it) and then hold the Jacobs chuck tight with one hand (or use tommy bars) and turn the headstock with the other hand. Keeping the chuck seated loosely in the tailstock allows it to draw forward but it is still supported and kept aligned by the tailstock. Hopes that helps. Tom Nance Corpus Christi, TX ------- Date: Fri, 05 Dec 2003 21:47:24 -0000 From: "n2562001" Subject: Re: Tapping on the Sherline Lathe Jerry G. I did provide the recommended drill ( #25 drill ) for a 10-24 thread. However, if you ever try using a inexpensive tap and insist on completing the job with it as some will do, it's far better to have less thread than a broken tap. Jerry Kieffer > Larger holes to prevent breakage might be effective, but the real > question is how much percentage of thread are you producing? > Too large can result in exceeding the pitch diameter. Consult a > good chart. Machinery's Handbook is a very reliable source. > Regards, Jerry G (Glickstein) ------- Date: Sat, 6 Dec 2003 04:55:53 -0800 (PST) From: Jose DeMoya Subject: Re: Re: Tapping on the Sherline Lathe Well said Jerry. Not only that, but many times when the tap breaks, your part gets scrapped. Especially when working with very hard metal, a slightly larger hole makes your life easier. Jose. ------- Date: Sun, 28 Dec 2003 02:14:21 -0000 From: "stertrac" Subject: how to thread drill rod Can anyone tell me how to thread oil hardening drill rod with a hand die? It cut alright on the lathe but the die just grinds the end off. Any help would be greatly appreciated. I am sure it is a right hand die and I'm turning it the right way. It must be as hard or harder than the die. I tried heating and cooling it as well. I can't replace the part and it's driving me nuts. ------- Date: Sat, 27 Dec 2003 20:55:49 -0600 From: "Ronald R Brandenburg" Subject: Re: Re: how to thread drill rod OK. Have you tried making a start, 0.010 to 0.015 single depth, with the lathe? Ron... Fort Worth, Texas ------- Date: Sun, 28 Dec 2003 00:39:06 EST From: jmartin957x~xxaol.com Subject: Re: how to thread drill rod Single point threading it on the lathe and following up with the die is one way. Another trick is to turn or grind a long chamfer on the end of the drill rod to help the die get started. If you have an adjustable die, you can try cutting a very oversized thread first, then following up with the size you want. The oversized thread won't cut on the crests, and you'll get less tearing. Make sure that your second cut is smaller enough so that the die cuts rather than rubs. Use threading or cutting oil. John Martin ------- Date: Sat, 27 Dec 2003 23:57:19 -0600 From: Jon Elson Subject: Re: Re: how to thread drill rod Yes, this is a tough problem. You might be able to thread it with the threading gears and a carbide 60 degree cutter. Chasing the thread with a single point tool can thread stuff that will destroy a tap. Sometimes you can get a tap to start if the part has a gradual taper on it. Annealing the part requires heating it pretty hot, definitely into the range where it glows, and then allowing it to cool very slowly. Jon ------- Date: Sun, 28 Dec 2003 02:21:46 -0500 From: "mertbaker" Subject: Re: how to thread drill rod Taper the end a bit to start the die. Be sure you have the die right end to. Mert ------- Date: Sun, 28 Dec 2003 02:40:57 -0600 From: "Ronald R Brandenburg" Subject: Re: how to thread drill rod Good point. Make sure the correct side of the die is toward the part. A die is tapered and you need to start on the side that has the largest diameter. Ron... ------- Date: Sun, 28 Dec 2003 18:00:23 -0000 From: "hooya10_4" Subject: Re: how to thread drill rod I've never had really great result's threading O-1 with a die, even a fine quality HSS one, on my 618. Even in an annealed state, it's really not that freely machinable, and seem's to tear & leave a rough thread, in spite of any thread lube. I usually single point it, and then chase the threads with a die. (especially if you're dealing with a large thread) John ------- Date: Sun, 28 Dec 2003 19:04:07 -0000 From: "Alan Barnett" Subject: Re: how to thread drill rod Hi, I would check that you are using a proper 'die' not a 'die nut' as these are for running down a cut thread, if you do try to cut a thread using a die nut I have found, if you do get it started the second thread will strip the first thread off. If I do get threads that are fighting back I put the bar in the lathe chuck, remove any centres from the tailstock, hold the die in its stock in front of the bar, push the tailstock to touching the die stock, lock off the tailstock, wind the tailstock handwheel until there is pressure on the die stock, ( now being held square by the tailstock barrel) turn the lathe ....by hand.... letting the die stock leg come to rest on the side of the bed, increasing the pressure on the tail stock as the thread is cut, When its started enough take it to the vice. Regards Alan ------- Date: Tue, 30 Dec 2003 06:25:01 -0800 (PST) From: helpx~xx4mtool.com Subject: Re: how to thread drill rod -Explanation It seems that everyone who replied to you forgot one of the basics of threading. If you want to, for example, cut 1/4"-20 threads on a shaft, the major diameter of the shaft (for a 2A fit) is .2408/.2489", NOT .250". Using the standard Unified Screw Thread tables in any Machinery's Handbook will show this. The "nominal" stock size is not the same as the major diameter. Measure any bolt to verify this. The die you use can to some degree upset the metal, as well as cutting it. All the good suggestions (taper, correct side of die, etc.) are of benefit, but try a smaller stock size. In the example we cited above a letter "C" drill rod would suffice. Regards, George O'Connor georgex~xx4mtool.com ------- Date: Fri, 02 Jan 2004 12:00:18 -0800 (PST) From: helpx~xx4mtool.com Subject: Re: how to thread drill rod -Explanation [after a query about whether his numbers used above are incorrect] No- Verify it with any handbook or UNC chart. In fact the minimum Major diameter for a 1A fit is 0.2367". George ------- Date: Tue, 30 Dec 2003 17:16:07 -0000 From: "Ernest Lear" Subject: Re: how to thread drill rod -Explanation Those odd thous. makes a hell a lot of diference to it screwing into a mating threand or not when you cut them with a single point tool in the lathe. I could never figure out at first why it would not screw in. When I made a threaded part, where the bit that it was to screw into was not at hand,when I came to fit it.Now I check the Max dia. for the thread being cut with the Micrometer for correctness before I take it out of the lathe. The thread form is also flat on top and not to a pointed form on the outer dia. If it don't work at first reasion why and that way you come good at doing it right the next or the time after. Regards Ernest ------- Date: Thu, 22 Jan 2004 04:32:20 -0000 From: "n5fee" Subject: Re: gears-618 crafstman I own a 9 inch South Bend and two Atlas 618 lathes. Several years ago I made an Excel Spreadsheet to calculate the hundreds of different gear combinations of each machine and then sorted the spreadsheets to show the different threads per inch (and mm per thread) possible with the gears I had avaliable. I used this for quite a while when I needed to cut an oddball thread on my machines. I later found a neat program at http://www.lathes.co.uk/screwcutting/ that makes this task easy for any lathe. The program lets you input the gears you have on hand and you tell it what you are trying to cut and how accurate you need. The program will then give you the different combinations of the gears you have on hand to do the job. It is very slick. There are three different versions on this site. One is made just for the Southbend and its stock gears. The other two programs are general in nature and can be customized for any lathe. There is also a text file with instructions. All three are worth downloading and saving. Dallas Shell Oklahoma ------- Date: Fri, 23 Jan 2004 03:02:15 -0000 From: "waynevarnadoe" Subject: Screwcutting program Does anyone know how to open "http://www.lathes.co.uk/screwcutting/". This program has 4 parts, and I can open "calculator 2" (diagram of gear arrangement) and "threadstext". I cannot open and run "South Bend & Boxford screwcutting" nor "General threads calculator". When opened you enter all the gears you have and what thread you want to cut and the program shows which gears to use and where. Thanks, Wayne in PC. ------- Date: Thu, 22 Jan 2004 19:11:02 -0800 From: "Steve B." Subject: Re: Screwcutting program save the files to your desktop, then rename them like this: southbend&boxford.exe see?, put the ".exe" at the end and them run the program. That worked for me. SB ------- NOTE TO FILE: The following messages about cutting left-hand ACME thread appeared in mlathemodsx~xxyahoogroups.com and has comments that are applicable to any brand lathe, particularly the lighter ones. The group where these messages appeared is primarily concerned with the 7 X whatever minilathes, which are increasingly popular. See "Lathe Comparisons" file for more advantages/disadvantages. A very accomplished micro-lathe fan bought one of these minilathes as an "attachment" to do threading instead of buying/building a threading attachment for his Taig. He was very pleased with it. ------- Date: Sun, 25 Jan 2004 22:29:00 -0000 From: "catfish7251" Subject: Left Hand Threads I have a HF 7X10 mini lathe and am new to threading. Is it possible to cut left hand Acme threads for a vice on it. Thanks Catfish ------- Date: Mon, 26 Jan 2004 01:52:46 -0000 From: "jjfear" Subject: Re: Left Hand Threads Catfish, Those are really two different questions. Any lathe with the ability to cut threads, can also cut lefthand threads. Almost every book on lathe operations will contain instructions for doing this. As someone new to thread cutting, I would suggest that you invest a little time and money in securing and reading one or more of those kind of books. A good source is Lindsay Books(www.lindsaybks.com) who sells reprints of older books which are better than modern books which devote space to CNC-CAM. Cutting ACME threads is more difficult either right or left. The Acme thread has a special thread form and can only be cut on a lathe with a form tool ground to the exact shape of the size of the thread needed. Seventy-five years ago, that might have been a common skill, but even experienced machinists find this a daunting task, and would be almost impossible for a beginner to accomplish successfully. The reason is that Acme thread rods in all sizes and both left and right hand threads are readily available from the normal industrial suppliers. They are not cheap, but compared to the time and effort to actually machine one, it pays. That would be my suggestion that you learn how to thread on a much simpler project. ------- Date: Sun, 25 Jan 2004 20:17:19 -0600 From: xlch58x~xxswbell.net Subject: Re: Re: Left Hand Threads Actually, almost all threads require a special thread form. Most people are lazy and leave the tip sharp, but the root of a standard thread is not a point, the width of the flat depending on the tpi. ------- Date: Sun, 25 Jan 2004 21:23:54 EST From: catboat15x~xxaol.com Subject: Re: Re: Left Hand Threads xlch58x~xxswbell.net writes: >>The Acme thread has a special thread form << I think the usual suppliers carry Acme thread gauges, like our ordinary "fish tail" but instead of the 60 degree V notch (sorry, to the Brits, a 55 degreee notch) but with the Acme thread shape on the end. Should go fairly easy if your lathe is in good shape and you go slow, plenty of lube and light cuts as it is a form tool and chatter could be a problem. ------- Date: Sun, 25 Jan 2004 18:08:50 -0800 From: Donald Qualls Subject: Re: Left Hand Threads catfish7251 wrote: > I have a HF 7X10 mini lathe and am new to threading. > Is it possible to cut left hand Acme threads for a vice on it. Yes. The mini-lathe cuts threads equally well in right hand or left hand; you'll need to set the tumble reverse and cut away from the chuck, and of course you'll need an accurately ground tool. That said, the mini-lathe is marginal on power to cut a thread like the Acme unless you use some trickery -- one way to improve things would be to eliminate chip crowding by using a pointed tool with the correct side angle cut cut in the leading and trailing slopes, then nibble out the gullet of the thread with a square tipped tool. You'll also most likely find it tricky to cut a coarse thread, like what you'll probably want for a vise, because the rapid feed both causes the advantage of the feed train to work against the lathe (the lead screw is turning faster than the spindle for any thread coarser than 16 tpi) and makes it hard to slow the spindle enough to keep proper track of the cut progress (though this is less of a problem when cutting away from the headstock as with a left hand thread). All things equal, it's probably easier and, by the time you ruin a few tool bits, might be cheaper to simply buy a length of the proper size LH Acme threaded rod from Enco or another supplier. Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. ------- Date: Sun, 25 Jan 2004 23:02:47 -0500 (EST) From: sculptor1x~xxcollegeclub.com Subject: Re: Left Hand Threads Certainly. But I agree with the poster who stated doubts concering the power of the mini lathe to cut coarse threads. I have difficult time cutting threads above 16 tpi with my 9X20 under power for the same reason. I would make a hand crank for the spindle, reverse the LS, and grind a tool to form. Acme threads have a 29 degree side and a flat point. Pick up a machinist's manual such as Machinery's Handbook and it will have all the specs and proceedure to cut the thread. I would NOT try to cut it using the lathe's motor. It is a sure way to pop the controller or strip one of the plastic drive components. The Mini-lathe has no resetable clutch to protect the machine's controller in the event the user overloads the lead screw (by cutting to agressivily, running the bit into the chuck jaws....etc) so when that happens something breaks and has to be replaced. I've stripped the plastic drive key out of 3 pulleys and broke two controllers when I first bought it because there are no damage control devices like industrial lathes have (expendable phenolic gears, slip clutch, etc...). Regards, Gabe ------- Date: Mon, 26 Jan 2004 08:38:03 -0000 From: "John Barrett" Subject: RE: Left Hand Threads Having cut a few in my time (a long time ago!) it was imperative to cut the square portion first, and oh so carefully form the flanks. Outside threads are easy enough but the internal one will cause you to swear a little! I owned a minilathe for a while and it is quite nice at thread cutting but it will be down on power and it will stress the components. If you are determined to generate your own LH threads, why not consider a LH ACME tap and die? I have seen a number on ebay recently at sensible money because no-one knows how to use them anymore! Regards John Barrett. ------- Date: Fri, 13 Feb 2004 18:16:39 -0000 From: "tony_m_baker" Subject: Re: Left Hand Threads > Cutting ACME threads is more difficult either right or left. Well, I'm afraid I have to disagree with you about it being too difficult. I have cut hundreds of acme threads in a lathe on valve stems, and if you buy an acme thread gage and spend a little time getting your tool ground right it is no different than cutting vform threads. I might advise a beginner to practice vform threads first, until they get comfortable with the general process of threading, but a little practice is all it takes. My only word of warning is to keep your depth of cut light. If you try to take too deep of a cut the tool can dig into the part causing the part to try to climb the toolbit. This will either break the toolbit, ruin the part or both. Besides the whole point of have a lathe is to make things. Right? There are a good series of article on threading at http://groups.yahoo.com/group/mwhints2/files/DuplexOnThreading/ ------- Date: Tue, 03 Feb 2004 19:25:21 -0000 From: volzmechatronicx~xxyahoo.com Subject: Re: Gingery shaper from castings It is always a pleaure to see again the Gingery shaper that "The Frugal Machinist" wrought. He used V-threads instead of Acme because of the high cost of Acme taps which are, if needed, available from Wholesale Tool in both right hand and left hand thread versions. Wholesale Tool also offers Acme threaded rods and nuts in both left hand and right hand versions. On some of my machine designs I have used these nuts, in "captive" form, instead of tapping. Much cheaper. Art ------- Date: Tue, 03 Feb 2004 20:59:40 -0000 From: "kc1fp" Subject: Re: Gingery shaper from castings You can get the Acme nuts in cast iron from McMasters which can be used for adding to a machine. They are basically a piece of threaded round CI stock with a generous amount of wall. Not a bad price either. JP ------- Date: Fri, 05 Mar 2004 19:35:59 +0000 From: "Del Stanton" Subject: Thread Forming Taps [taigtools group] Thread forming taps have come up in recent messages. A thread forming tap has no cutting edges. The ones I have seen are tri-lobular at the tip. That is the cross section of the tap is like a triangle with rounded corners and rounded sides. From this shape the tap's cross section gradually morphs to a circular cross section. As the tap is driven into the material it forms the threads in the material by displacing material. The thread forming tap probably requires a larger diameter hole. I see the following advantages with thread forming taps: - The resulting threads are smoother and stronger. - There are no chips to jam the tap and cause tap breakage. - The problem of chip removal from blind holes is gone. - Without the grooves required to establish a cutting edge and allow a space for chips the tap is much stronger. I have a feeling that a thread forming tap might work longer, having no cutting edges to dull. Disadvantages: - Not readily available - They probably cost more When I was working at Haas Automation, the CNC machine toll manufacturer, the tool change disk was made from cast aluminum tooling plate. The spring type tool holders were fastened to this plate with two 1/4-20 socket head cap screws and the holes were being tapped with conventional thread cutting taps. There was trouble in assembly with the socket head cap screws stripping out the tapped holes. To overcome this problem they were buying longer socket head caps screws and cutting them off to the required length, thus having the screw's threads engage all of the threads in the tooling plate. (The tip of a socket head cap screw is tapered, and they are always somewhat shorter than the catalog length. Thus a 3/4 long 1/4-20 socket head cap screw might be "missing" three to four threads at its tip.) I suggested that we tap the holes with a thread forming tap and, as I dimly remember, the strip out torque went from 15 foot pounds to 25 foot pounds. So in cast aluminum there is a clear advantage to thread forming. Of course this this eliminated the bother and expense of buying longer socket head captscrews and having them cut off to length. Del Stanton Wannabe Taig CNC Mill Owner ------- Date: Thu, 04 Mar 2004 16:58:28 -0000 From: "azbruno" Subject: Re: Metric Threads w/o Reversing? > I want to put a 52 - .75mm thread on a chunk of metal to convert my > telephoto lenses into telescopes, and my Atlas 6x18 doesn't have a > reversing switch on the motor. I suppose that given the fine > (shallow) threads, I could try to cut the thread to depth in one pass. Given the application you mention, I'm assuming the length of the thread will be rather short. For my 618 I made a hand crank for the spindle and do all my threading that way (also, rather short lengths). I remove the motor belt to eliminate resistance and I can turn either direction easily. It's a lot easier than starting and stopping the motor and enabling the half-nuts on the move. I can be very precise about starting and stopping points and don't have to worry about cutting landing grooves. Bruno ------- Date: Thu, 04 Mar 2004 09:51:28 -0800 From: William Abernathy Subject: Re: Re: Metric Threads w/o Reversing? dswrx~xxwebtv.net wrote: > I understand members of the 7x10 group use a similar crank method. > Could you describe the crank and the way you mount it to the lathe? The preferred method is to take a bar that fits inside the spindle with a generous dollop of slop, and overbore the bar for a bolt you'll pass through it (say 3/8" bore for a 1/4" bolt). Next make a long diagonal cut like a salami slice through the bar (a bandsaw comes in handy for this, but you can also hacksaw and file the edges flat.) Pass your bolt through both halves of the work, such that there are threads hanging out at the end. Affix a crank handle to that end. Clamp it all together, loosely, with a nut. To use it, place the works down the spindle bore at at the head end, and tighten the nut. This drives the two halves of the bar outward, providing a powerful wedge grip in the spindle bore, and enable you to turn the spindle by hand. Do not overtighten this, and you may split the spindle. You can also see this wedge-type retention device used on bicycles to hold up the handlebar stem. I'd recommend the photo in the mini-lathe group to you, but the photos are down right now. If memory Serves, Mike Taglieri's section has some good photos of this mod. William ------- Date: Thu, 04 Mar 2004 18:36:27 -0000 From: "azbruno" Subject: Atlas 618 Handcrank (was Re: Metric Threads w/o Reversing?) I put some pictures in the Atlas618lathe group photos section (under Bruno's Lathe folder). It is an expanding mandrel. I made a piece that fits into the back of the spindle with a tapered bore at the end, and 3 slits to allow it to expand. There's a piece that fits through it with a matching taper on one end, and threaded on the other end, which sticks out the back side. I use a wing nut on the end to hand tighten it. I make a crude, but effective crank for it. And many thanks to John W. who helped me with this project. Bruno ------- Date: Sun, 14 Mar 2004 13:10:08 EST From: n8as1x~xxaol.com Subject: Re: Speeds, Feeds, and DOCs wuz Re: Progress Update - 7" Amm... [NATURALLY THESE GEMS CAME FROM THE Metal_Shapers GROUP] 6X48 carbon taps on rifle receivers & barrels ....never broke a tap using" crisco" (Gott zu danken)....when i did break a carbon tap in 1018,was able to shatter it & pick it out , quite unlike the hi-speed tap that gave me an hours misery........reckon there is enuf oil in the mayo for tapping ,if calories mean anything..think i read once that the original was tallow (beef fat rendered) also sperm oil in the whaler days..& i reckon bear fat for the mountain man...still have 3 coffee cans lard in the freezer from neighbors last hog killing (mix w/30wt non det. for hvy duty, kerosene for sawing, to ur taste), or just smear it on as is (also use w/ sulfur & aspirin mix for itchy fungusy probs in unmentionable sections of body parts, if u cant get hydrophilic ointment to mix sulfur/aspirin with,or find the vaseline)..still laughing over wifes comment as i mixed up a new batch last week..(really great cure ,huh? ,u been using it for 40 years!!!)....keep ur favorite critters well away from the delectable metal chips!!!! ( seriously) best wishes docn8as ------- Date: Mon, 22 Mar 2004 11:59:38 -0800 From: "Bob May" Subject: Re: Ever whittle your own taps? That is basic threading on your lathe! If you want to make a tap for use off the lathe, taps aren't hard to make. Start with some hardening steel and cut the thread that you need to the size you need. Next is to go to the mill and make the cutting edge grooves in the body of the tap (you can do it first but then you have interrupted cuts which are a bit harder on the job to handle). Finally you relieve the tap behind the cutting edge with a hand file, filing down a few thousandths (a single good pass of the file is usually enough) so that the full diameter of the teeth are only about a small fraction of the circumfrence - a little ledge is better than a completely pointed tooth. Taper the first few teeth so that they will help start the thread and make sure that there is relief on those teeth also. And finally harden the tap and temper it so that it will last for a while. Bob May http://nav.to/bobmay NEW! http://bobmay.astronomy.net ------- Date: Mon, 22 Mar 2004 22:37:19 -0000 From: "Ernest Lear" Subject: Re: Ever whittle your own taps? Single tool thread cutting is not that hard to do. You plan the way you going & how before you act and you will get the end result that you want without any problems. Have a go and be proud of the end result. I was scared stiff before I cut my first thread but after I did it I wondered why, as it was so easy to do. Now not having a tap or die don't worry me as I set it up and do the job on the lathe. Regards Ernest ------- Date: Mon, 22 Mar 2004 22:58:24 -0000 From: "jimmac70817" Subject: Re: Ever whittle your own taps? I know the joy of making it yourself but 1 1/2x8 threaded backplates are stocked by many suppliers. Jim ------- Date: Mon, 22 Mar 2004 22:17:28 -0600 From: "jerdal" Subject: Re: Re: Ever whittle your own taps? The happiness of not having to do it is later exceeded by the annoyance of the blinking poor workmanship on a lot of those plates. They get $40 for a badly done threaded plate when you can do a good thread in a $13 blank yourself (Victor Machinery prices a year back). However, you will need an existing mountable chuck, or a faceplate of some sort, in order to do it yourself. it is worthwhile to do, however. If nothing else, you will "get your feet wet", and realize the machine was made to do that stuff. Quite frankly, that is an elementary lathe application. At some point you gotta be able to do it right when it counts, might as well be now......... Jerrold ------ Date: Tue, 23 Mar 2004 23:05:46 EST From: catboat15x~xxaol.com Subject: Re: Making taps For small taps (less than 1/4 inch) I often make my own by cutting a thread on the proper size drill rod (silver steel for those on the other side of the pond) then grinding or filing a taper on the working end. Harden and temper then touch up with a stone and there is a good tap. You may have to back out more often for chip removal, but cheap and effective. Also a good way to make home made reamers, same way, but of course no threads. If you are into model making it is worth while to learn to use drill rod to make special tools such as counterbores, reamers, taps, special taper reamers, really small center punches etc. John Meacham High desert of California ------- Date: Mon, 31 May 2004 11:50:25 -0500 From: xlch58x~xxswbell.net Subject: Re: Adjustable Die patmack_1 wrote: >I'm a very low level novice ! Recently ordered a 5 X 40 die needed >for a model project. It has a split with a screw for adjustment. >How does one determine how and when to use the 'adjustment' to obtain >an accurate and true size thread ??? It must be there for a reason. The adjustment is used for a couple of things. First, a die takes a pretty big bite of metal when cutting, which can lead to a rough finish among other things, so the adjustment allows you to take a roughing and a finishing cut. Second, the adjustment allows you to adjust the "fit" of the thread, so that you can cut a rod with a loose thread(like on a a rod used for positioning something) or a tight thread like on an adjustment handle. Since you are a new user, I will also point out a few other things. One, the rod you are going to thread should have a 45 degree chamfer on the end at least as wide as a single thread if possible. This will help starting the die. Second while starting a tap off at an angle is pretty well discussed, the same thing can and often does happen with dies. Cheap button dies often have the threads at other than 90 degrees to the face of the die, so extra care should be taken here to insure the threads are 90 degrees to the axis. Dies will also tend to cut deeper on one flute, so your thread may not be centered on the rod. Most of these issues are not huge for the run of the mill handy man job, but for something high precision, I tend to start the thread on my lathe to insure it is centered and then chase it with a die to get the proper thread form, since I don't have a ready assortment of threading bits all set up for each pitch. If the job really matters, the extra effort is worth it. As someone else on the internet said, "a drunken thread never sobers up". For your 5-40 screw, the lathe is probably out since you have to spin something that size pretty fast for a good finish. I personally don't do much work that small, but if it was me, I would set up for a roughing followed by a finishing cut. Tapping the hole for it is likely to be more exciting. Charles ------- Date: Wed, 2 Jun 2004 00:44:40 EDT From: anthrhodesx~xxaol.com Subject: Re: 48 threads per inch.... In a message dated Tue, 01 Jun 2004 "davidzerocool69" writes: << help....i have a 101.07301 6 inch craftsman lathe... trying to do the thread chart configuration for 48tpi i discover that i dont have a 16 tooth gear for my spindle.... >> I've never heard of an Atlas built 6" lathe that didn't have a 32/16 compound gear on the reverse tumbler. How did this come about? << no big deal, just grab a computer and calculate the difference... but ive worked a week on this part, and want to double check... if the first gear was supposed to be 16, but i only have 32---- can the last gear that was supposed to be 48 be changed to 24 and still get the same results??? seems like it, but im not sure its that simple.... >> No! It works the other way around. With a 16 TPI leadscrew and wanting to turn a 48 TPI thread you need to gear the leadscrew down from the spindle in a ratio of 1/3. What this accomplishes is, while the carriage travels 1/16" during one revolution of the leadscrew the spindle will have made 3 revolutions thereby cutting three threads in 1/16" or 48 threads in 1". Having looked at the 6" change gear chart you are correct, it calls for the 16 at the reverse tumbler driving a simple gear train with a 48 on the leadscrew. A simple gear train is one in which all gears except the first and last ones both receive and pass on drive through the gear teeth, no transfer by shafts. In the case at hand the shafts on which the intermediate gears rotate serve merely as pivots, no longitudinal transfer of motion to another train of gears. So, starting with a 32 at the reverse tumbler the equivalent of the original train 16-x-48) would be 32-x-96. You've probably noticed you dont have a 96. All is not lost. As long as you can set up a train that will give the necessary 1/3 reduction you can still cut your 48 TPI thread. In this case we're going to use the 32 at the reverse tumbler and the 48 at the leadscrew. In a simple train this would result in a 24 TPI thread, twice as coarse as you want, so you need to add an additional 1/2 reduction in the train from the 32 on the reverse tumbler to the 48 on the leadscrew. Fortunately you should have a 20 and a 40 with which to do this. Set up the following train: Spacer on the leadscrew next to the support bearing. 48 beside the spacer with a nut holding the 48 and spacer on the leadscrew. On one of your intermediate studs, install a change gear bushing that has the keys on its outside. On the bushing install the 40 closer to the headstock and the 20 away from the headstock. Install this assembly on the change gear banjo with the 20 driving the 48. Swing the banjo up so that the 40 is now driven by the 32 on the reverse tumbler. You will now have the mathematical equivalent of the original setup. This is demonstrated by making a computation where the driver gear are placed on top of the formula and the driven gears on the bottom of the formula and multiplying by the pitch of the leadscrew which will give the resultant pitch to be cut. In this case: (32 x 20) / (40 x 48) x 1/16 = 0.02083333" pitch = 48 TPI If you can't set up this train due to interferences either put an extra gear in the train between the 32 and 40 using the second change gear stud. Any gear will do, it won't change the overall ratio as it goes into both the top and bottom of the formula thereby cancelling out. If you still can't set up this train an alternative is: Spacer and 64 on the leadscrew. 24 and 36 on the intermediate stud with the 24 driving the 64. Swing the banjo up so the 36 is driven by the 32 on the reverse tumbler. I'll let you make the mathematical computation. Notice that these are second and third ways, besides the way provided on the chart, to accomplish the desired 48 TPI thread. Always try to remember what the desired result is and understand that, if you can't accomplish it through the "official" procedure, there may be alternatives available to you. Hope the above is helpful beyond the immediate problem. Anthony Berkeley, Calif. ------- Date: Mon, 7 Jun 2004 12:42:55 EDT From: anthrhodesx~xxaol.com Subject: Re: 48 threads per inch.... In a message dated Sun, 06 Jun 2004, "davidzerocool69" writes: << an interensting point that you had made that i had never really realized was that many of the "idler" gears ( i think that is what you call them ) dont change anything... they just pass along an equal motion.... >> That's approximately correct. Lets suppose you have a 20 driving a 30 driving a 40. In one revolution of the 20 it will drive 20 teeth. At that point the 30 will have made 2/3 of a revolution. It will pass on a movement of 20 teeth to the 40 which will have made 1/2 of a revolution. So for the purposes of calculating a simple gear train you can ignore the idler gears and calculate the ratio between the first and last gears. Two points to be made about the above. In order to calculate a compound train you essentially calculate multiple simple trains and then multiply the simple trains together to get the final calculation for the entire compound train. And you'll notice I said you were approximately correct. The other consideration is reversal of motion. Count the number of axles in the train. including the first and last ones. If the stud gear (the one on the reverse tumbler) could drive the screw gear directly you would have reverse rotation. The usual setup is one intermediate axle, either an idler or compound gear. In this setup you get double reversal of motion or same direction as the first gear. So if you count the number of axles you can tell whether the motion is reversed or the same, odd number of axles equals same, even number equals reversed. To illustrate the point, look at your reverse tumbler. When only one of its gears passes motion from the spindle gear to the stud gear you will observe same direction of motion. When the rotation has to pass through both of the tumbler gears the stud will rotate opposite to the spindle. Always try to understand the principals, it will help you in everything you do, whether machining or anything else. Anthony Berkeley, Calif. ------- Date: Mon, 14 Jun 2004 15:35:03 -0400 From: "Jerry Glickstein" Subject: To Cross Chread or not to Cross Thread Tip of the Day. To prevent cross threading. Engage mating threads, male and female. Gently turn opposite the normal assembly rotation while keeping a very light pressure between the two parts. You will hear and feel a slight "click". Stop, and screw together normally. You have found the exact start of the thread. Normal assembly rotation is clockwise for right hand threads " " " " counterclockwise for left. This does not apply to multi-start threads. Regards, Jerry G (Glickstein) ------- Date: Tue, 15 Jun 2004 18:16:22 -0000 From: "Glen Reeser" Subject: Re: To Cross Chread or not to Cross Thread I use a lot of multi-start threads for pen caps and barrels. Usually triple start 12 threads per inch for a total of 36 threads per inch. The "turn backwards 'til it clicks" trick works every time. Glen Reeser ------- Date: Tue, 29 Jun 2004 01:23:16 -0000 From: "azbruno" Subject: Four lead threads [atlas618lathe group] Over the weekend I made a part in which I needed to cut a four lead 32 TPI thread. I cut four lead 36 TPI threads all the time and the differences in machining the two types was quite an education. For a four lead 36 TPI thread, I set up the gears for 9 TPI. My lathe has a 32 tooth threading dial, but I bought a 16 tooth threading dial for it some time ago so I can cut one lead on each one of the four marks on the threading dial. Couldn't be easier. Well, the 32 TPI thread was quite a different story. I set the gears up for 8 TPI. But I could not find any way to use either the 16 or 32 tooth threading dial do get the desired result. The solution was as follows. I cut one lead using any of the four marks on the threading dial (16 tooth). Then, I slipped the threading dial one tooth and cut the second lead on any of the four marks. Next, I had to slip the compound gear by 8 teeth and repeat the process for the next two leads. I found a little White-Out to mark the compound gears to be of necessity as it's easy to loose track when slipping 8 teeth. When I cut the 36 TPI thread, I can cut each lead at the same compound setting, so I can test the part with it's mate when I get near proper depth. But with the 32 TPI method, I basically need to cut each lead to depth. That means that if I have to deepen the threads, I need to muck with all the gears again. Real pain. When I chose 36 TPI for the four lead threads, I had no idea how good a choice that was, knowing that 32 TPI has often been used for the same function. Happy Threading! Bruno ------- Date: Mon, 30 Aug 2004 03:31:08 -0000 From: "azbruno" Subject: Re: thread depth calculation In atlas_craftsmanx~xxyahoogroups.com, "catman60957" wrote: > Hello, I have a 12X36 Craftsman and I have a few questions about > threading. When using the compound to advance the thread depth, if > you move the handle .005 are you still taking .010 off the part? > I tried to download one of the files marked threading depths and > formulas but could not get it to work. > Can anyone tell me how to calculate the amount of material to remove > to make said thread? Is there a chart that I could download? > Any help would be appreciated. Thanks, Tim Lewis Answer 1: If the compound is set to X degrees off perpendicular to axis, you multiply the amount you move the compound by Cos(X) to determine the amount you're moving straight in. For example, in threading you may have the compound at 30 degress, so for every .100 on the compound dial, you're going into the work .0866 (perpendicular to the axis). Answer 2: To determine how far to advance the compound for a thread, it also depends on the shape of the thread, shape of the tool, class of fit, angle of compound, etc. Assuming a compound set at 30 degrees (because the math is easier), external thread, a sharp V tool where you won't have a flat on the root, and you want a proper 1/8 flat on the crest, you'd advance the compound by 7/8 of the pitch. So, for example, a 20 TPI thread should be advance 1/20 * 7/8 or .04375. But if the tool is formed for a 1/8 flat at the root, you might advance 3/4 of the pitch (or .0375 for 20 TPI). For an internal thread, you may want a 1/4 flat on the crest and 1/8 on the root, therefore you'd calculate 5/8 times the pitch. Answer 3: Same as answer 2, but the trig approach for compound set to X degrees... Use method in answer two, and multiply the result by Cos (30) / Cos(X). So, for a 29 degree compound, 20 TPI thread, V formed tool with 1/8 flat at the crest, the value calculates to .04332. Hope this helps. Bruno ------- Date: Mon, 30 Aug 2004 12:51:15 -0000 From: "mineralman55" Subject: Re: thread depth calculation > you won't have a flat on the root, and you want a proper 1/8 flat on > the crest, you'd advance the compound by 7/8 of the pitch. Where does the 7/8 factor come from? As a quick, back of the envelope calculation, I take the screw pitch, invert it, and subtract 10% to get the amount of infeed needed when the compound is set at 29.5 deg. Example: 10 TPI: 1/10 = 0.100; 0.100 - (0.100 * 10%) = 0.090 Example: 16 TPI: 1/16 = 0.063; 0.063 - (0.063 * 10%) = 0.056 Close enough for "gummint" work (no, I don't officially work for the gummint, at least not until after "Tax Freedom Day".) Larry New Orleans ------- Date: Mon, 30 Aug 2004 14:37:25 -0000 From: "azbruno" Subject: Re: thread depth calculation Larry, on a 60 degree V thread with no flats, one side of the V is the same as the pitch (which is 1/TPI). If leaving a sharp V root, but wanting a flat on the crest that is 1/8 of the pitch, you're left with 7/8. While your approximation may be close, you're a few percent high. Do you keep a calculator next to the lathe? Bruno ------- Date: Tue, 07 Sep 2004 11:18:04 -0000 From: "azbruno" Subject: Re: Thread numbers > I understand the last numbers in a thread size stand for the TPI but > does the first number..(6) from a screw sized 6-32 mean it is derived > from a fraction or what? I don't have a book that converts this first > number or explains what this "first" number is. Thanks in advance for > your reply. Donald #0 is .060". Each number above, add .013". So a #6 is (6 * .013) + .060 = .138". For 00, 000, subtract from .060. So a #000 would be .034". ------- Date: Mon, 13 Sep 2004 07:19:22 -0700 (PDT) From: DOUG BLODGETT Subject: Re: How to make Thread 1mm /tiny diameter ?? >any website about this tapping/making thread 1 mm diameter or 2 mm ? The Tap and Die Company sells taps down to .8mm in size. Try www.tapdie.com/index.html Doug Blodgett ------- Date: Sun, 19 Sep 2004 22:10:07 -0700 From: "Marcus and Eva" Subject: Re: Re: Foredom 25H handpiece as a lathe spindle? [sherline group] >>> the intention is to place the handpiece on the tool holder. The leadscrew will be fed through the threading accessory and the part to be thread will still be on the headstock. No changes there. The handpiece will only replace the cutting tool. regards, Mike <<< Hi Mike: I do this all the time. I thread tiny titanium screws (down to 1.25 mm diameter) this way and it works very well. There should still be a blurb in the files section on my setup. I think it's called "Machining Tiny Threaded Part" or something like that. I'm using a 34,000 RPM Foredom handpiece that's got to be 15 years old at least. It's the model with the precision collets, not the drill chuck and not the crude and crappy collets. My cutters are custom ground two flute carbide, 1/4" in diameter with zero top rake and 5 degrees of front clearance on each flank. I rough grind them with a 150 grit diamond wheel and finish the cutting edges with a 320 wheel. If I grind them with just the 150 grit, they don't survive as long. There's another blurb in the files section called "Cutter Grinding 101" that shows the tools I use to make the cutters. When I cut the threads, I use a two pass protocol...the first gets me within 0.001" of final size, the final pass is to size. I find I get a cleaner thread that way. I use Rapidtap as cutting fluid for all metals, not just titanium. The method is a very good one...I recommend it for small threads without hesitation. Cheers Marcus ------- Date: Tue, 21 Sep 2004 16:14:53 -0000 From: "Larry Nicks" Subject: Re: Foredom 25H handpiece Hi guys: I bought a 25H handpiece specifically for use as an engraving spindle on my homemade CNC router. I found that the radial runout was under 0.001" and the collets are good quality. BUT- the axial slop made it unusable as received. Foredom designed in over 0.010" of axial clearance (I think it was over 0.020", but it has been a while). The original bearings were a wide (not common) version of the common 608 skate bearings. I ended up replacing each of the original bearings with a pair of ABEC7 608ZZ's and shortened the original spacer. I used a light belleville spring washer at the drive end to give about 7 pounds of preload. That removed all axial slop, but the handpiece now runs too warm to comfortably use by hand and I don't expect the bearings to last a long time - but for occasional use at up to about one hour at a time at 15,000 rpm, I've got a pretty good engraving spindle. When the bearings go, skate bearings are real cheap and it only takes about 10 minutes to change them. Larry ------- Date: Fri, 22 Oct 2004 03:25:58 -0000 From: "Barry" Subject: Thread Cutting on Atlas 3996 12" OK, I am new to lathe work so please bear with me. When cutting threads, Is it just a matter of setting the QC levers according to the thread chart on the QC box? I set mine up to cut 24tpi just to see if it was right and it cut 12tpi. I had the QC lever set to what I assume is B position and the carriage feed lever under the column with 24tpi in it. The letters on the QC plate are not readable. From all the pics I have seen it should be as follows E C A D B Is this correct? Does spindle speed affect cutting threads?I had mine set at the slowest speed with the back gear out(164 rpm I think)? Again I am new and just learning how to operate a lathe. ------- Date: Mon, 8 Nov 2004 13:00:52 -0800 From: "Marcus" Subject: Re: Threading attachment [sherline group but applies anywhere] One of the best kept secrets to single pointing nice clean threads is to get some side rake onto the tool. You have to make sure it's on the flank that will be formed...NOT the flank that will be generated, and this, of course depends on the hand of the thread, and on the feed direction. If you intend to form both flanks, you need top rake, not side rake, and you have to distort the shape of the tool to accommodate the deviation from nominal profile that will be created by the top rake. To describe the difference for those unfamiliar with threading terminology: When you set the compound slide over to one half the flank angle (30 degrees for a typical 60 degree vee thread), one flank of the tool will cut full width on the last finishing cut, while the other side of the tool will have never taken a cut. The formed side is the side that the cutting tool takes the full width cut...the threading tool is a formtool with respect to this side of the thread, so its geometry must be good. The other side is "generated" by the advance of the compound slide along the trailing flank of the thread. If you leave your compound slide set at 0 degrees and advance the tool in with the cross slide, you will form both thread flanks, and the chips from each side of the tool will converge in the center and pile up there. Putting side rake on the forming side of the tool preserves its 30 degree angle, but the side rake makes a nice downhill slope that the chip can run down as it's peeled from the stock. This, of course, goobers the angle of the tool on the generating flank and puts it below center, but since it's not cutting anyway, it doesn't matter. In fact, you can just grind it away, and still get a perfect thread, BUT ONLY SO LONG AS YOU CUT YOUR THREAD WITH THE COMPOUND SET AT 30 DEGREES AND USE IT TO ADVANCE THE TOOL INTO THE STOCK AFTER EACH PASS!!! Most shop manuals state that the threading tool should have zero top or side rake: this forces the chip to make an abrupt direction change, so you get high loads and crappy finishes. The reason they insist on this, is that the tool grinding and setup is simplified if you put no rake on the tool. It also lets you form the trailing flank by setting the compound over only 29 1/2 degrees, and having the trailing flank cutting full width too, but that's kind of self defeating although it's widely taught. Since it's harder to set up a tool that you can't so easily verify with a threading gauge, you need to pay a bit more attention in the setup: Get a cheapo 10X magnifier, and simply set the tool so the forming flank of the tool is at the correct angle. When it's OK, the thread will be good, so long as the trailing flank was not ground too obtuse. Put 5 to 10 degrees of side rake on the tool, remembering which flank needs to be preserved, and away you go. If this is clear as mud to anyone, give me a shout back!! Cheers Marcus ------- Date: Mon, 8 Nov 2004 16:12:38 -0500 From: "Jerry G" Subject: Re: Threading attachment Marcus, I'm sure your explanation has scared the pants off anyone who wanted to cut a thread and was lured into buying a Sherline Lathe for the "fun" of machining. I had always ground in ample side rake, slight top rake (depending on the material) and produced nice clean threads. I also cut threads with the compound set over 29 and a 1/2 degrees, and cutting straight in with the cross slide only. I used a pitch mike to control the size on the way to the "right place", then measured for the "goal" using the three wire method. As you know, finding the best wire diameter is the time consumer :)exactly Regards, Jerry G (Glickstein) P.S. No shout from me, because I know exactly what you are talking about :) P.P.S. The three wire method of measuring threads is the selection of the right diameter for the pitch of the thread being checked, Placing two of the three wires on one side of the thread and a third opposite so that the anvils of a micrometer reads over the three wires. There is a formula to arrive at the correct pitch diameter. The wires must enter the thread and extend over the crest of the thread. The "best" wire is the one that touches the thread at the mid slope of the thread. ------- Date: Tue, 09 Nov 2004 18:48:27 -0000 From: "n2562001" Subject: Re: Worm Gear Hobbing Questions.... > Just for fun, I am attempting to "hob" a worm gear set for a rotary table > for my Taig Mill. I plan to use a technique I found on the web based on > using a standard threading tap. Steve Steve, personally I think who ever first figured out how to do this and then suggested it to others should have been hung by his or her toes. With this method there is no way to get a consistent worm pitch line and you end up with very little tooth and tooth contact. Cutting to any particular size is just about impossible unless you get lucky. I personally have never been able to machine gears with this method, nor Have I ever seen anyone else where the gears perform anywhere near properly cut gears. Gear sets are available new and used from many sources such as old windshield wiper gear boxes. While not desirable for this application they will be far better than using the method above. If you must do this you can cut the worm gear using a 60 degree threading tool as a gear cutter. Just mount the threading tool in a fly cutter and cut the gear using standard gear cutting formulas based on the thread you wish to use. This will produce a worm gear with proper size teeth and greater tooth contact area that will be able to be adjusted for back lash. Playing around is one thing but if your trying to produce an accurate usable rotary table I think you will find that just the materials will cost almost as much as a good commercial table. Jerry Kieffer ------- Date: Tue, 9 Nov 2004 11:12:45 -0800 From: "Larry Richter" Subject: miniature rotary tables are down to $70 or so at Harbor Freight > I think you will find that just the materials will cost almost > as much as a good commercial table. Jerry Kieffer A three inch table at that price last month. Four inch at about $100. That's shipped. Hard to justify building at those prices unless building is a LOT of fun. ------- Date: Tue, 9 Nov 2004 12:12:32 -0800 From: "Felice Luftschein and Nicholas Carter" Subject: Re: Re: Worm Gear Hobbing Questions.... I agree that this method is iffy at best - if the stars are aligned you could conceivably get it to work, but having tried it once (three times) and ruined three blanks I would put it in the "great idea, but..." file. When I made a worm gear for my home made dividing head I made a blank and used a single tooth 60 deg. flycutter that had a cutting diameter of 3/4", and used a 3/4"-10 piece of screw for the worm. When you use a cutter the same diameter of the worm you can get the same radiused tooth profile you want for a worm. You could also use a tap that has all but one row of teeth ground off as the flycutter, but that's expensive unless you find one used at a cheap price... Of course then you need a way to index the blank around, which is the reason for the siren call of the "hobbing" method in the first place. Check out our homepage www.cartertools.com/nfhome.html ------- Date: Tue, 09 Nov 2004 20:53:51 -0000 From: "n2562001" Subject: Re: Worm Gear Hobbing Questions.... Tom, the threading tool method that I use on occasion while far better than the tap method is still far from professional by any means. I only use this in a non critical situations where cost and time is a factor for such things as maybe a old toy repair. I am not into hobs for the simple reason I can make ten sets of worms and worm gears in the time it takes to make a hob. The problem with a hob is that the matched set will only be as close as you are able to cut the worm in relation to the hob. This is of course no problem with a matched set of commercial cutters. I have done several Seminars on worm and worm gear cutting for model Engineering , Watch and Clock regionals etc.. My method is as follows. I first machine and harden a single point cutter to the desired DP from A-2 drill rod. I machine and harden because I can machine far more accurately and faster than I can grind. Next the worm gear is cut using standard gear cutting formulas with the single point cutter. Next the single point cutter is put in the lathe and a worm is cut using a standard threading setup. (Hand crank works best.) By using the same cutter for the worm you can get a very close fit. I am also able to put the worm gear over the worm before removing the worm from the lathe since I have already cut it. This allows for a even closer fit under magnification. Fit is achieved by how deep the worm thread is cut. My personal motto is that "My opinon is no better than what I can demonstrate". Whenever doing a Seminar, I always make it a point to machine a cutter, worm, and a worm gear from bar stock during the Seminar. The cutter takes ten minutes, the worm is about ten minutes and a small worm gear is about fifteen minutes. When completed the worm and worm gear are passed around along with a 5X magnifier for all to inspect the quality of fit and finish as well as tooth contact percentage. Jerry Kieffer ------- Date: Tue, 09 Nov 2004 22:23:59 -0000 From: "davideggy2" Subject: Re: Worm Gear Hobbing Questions.... "steve sc" wrote: > Just for fun, That's the key, "just for fun". Give the tap idea a try before you let anyone scare you off. > I plan to use a technique I found on the web based on using a standard > threading tap. I used a fast spiral tap. This works good cause there are always teeth in the material. It's a nice smooth run around the blank. A standard tap will chatter. I marked the blank where I "plunged" the tap in (actually it's the blank that's moving) and watched this spot as it came around. The blank "jumped" as the tap slipped into the cuts it made on the first pass around. On subsequent passes, the "jump" became smaller until it perfectly meshed. You can keep going, taking off more material until it again stops jumping and you have one less tooth in the gear. It's easy to get the right size blank using a little math. Try it first in something soft and cheap. I used a piece of plastic cutting board on a wood lathe. > It appears that it makes sense to "pre-groove" the gear blank with a > groove that is approx the same radius of the tap. How deep to cut that > groove? It would seem that cutting a deeper groove would result in teeth > with more surface in contact with the worm; however, going too deep and > the teeth would appear to bind against the worm??? I am thinking that > the gear blank should be something like 3/8" thick (or more???) for > a 1/2" tap...??? You can try the pre-groove idea. Maybe make the groove the same size as the tap drill. 27/64" for a 1/2-13, I believe. Anyway, it's cheap, easy, and above all, FUN. That's what a hobby's all about. HTH, Dave ------- Date: Wed, 10 Nov 2004 00:33:24 -0000 From: "stevenson_engineers" Subject: Re: Worm Gear Hobbing Questions.... Hobbing using a 5/8" x 8 Acme tap. [NOTE: run address lines together into one line with no space] http://homepage.ntlworld.com/stevenson.engineers/ lsteve/files/hob%20indexer21.jpg Close up. http://homepage.ntlworld.com/stevenson.engineers/ lsteve/files/hob%20indexer23.jpg Some examples:- http://homepage.ntlworld.com/stevenson.engineers/ lsteve/files/hob%20indexer26.jpg John S. ------- Date: Wed, 10 Nov 2004 15:54:18 -0000 From: "wishbone_aaa" Subject: Re: Worm Gear Hobbing Questions.... > Just for fun, I am attempting to "hob" a worm gear set for a rotary > table for my Taig Mill. I plan to use a technique I found > on the web based on using a standard threading tap. I used the same method to build an indexer that mounts on to my Taig lathe headstock. There can be a problem with getting the correct number of teeth on the gear. I had to slightly reduced the blank diameter to get it come out right. Most texts recommend that blank be gashed before using the hob, but not having an indexer to start with, I started the hob into blank with a light cut. Found that it all worked better than I expected. There's an old Popular Science article on hobbing worm gears in one of the metal working groups that J. W. Early has setup. He has a number of groups,so I can't tell you in which group to look at this time. Also Jose Rodrigues has a video tape on making gears that I found very helpful. You can find the URL on Nick's site. Don ------- Date: Sat, 11 Dec 2004 21:44:47 +0000 From: "steve sc" Subject: Worm Gear Update (success!) Well, time to report back in on my experiences making a worm gear with a tap. Bottom line, it worked *great* (but it took alot of prep work!). I loaded a web page that sketches out my experiences with a bunch of pix. Thanks to all those who gave me encouragement and also to those who put the fear in me (in made me all the more determined to make it work!). http://home.comcast.net/~l.scampini/wormgear.htm Steve [LATER MSG] OK, I think I fixed my worm gear page to work with both IE and Firefox. I also added a last picture of a close up of the gear (as close I can focus). ------- Date: Sat, 11 Dec 2004 15:04:36 -1000 (HST) From: benedictx~xxhawaii.rr.com Subject: Re: Worm Gear Update (success!) The pics showed up great for me. I gotta say, well done Steve! That's a beautiful looking gear! I seriously like the way you gashed the blank. I wouldn't have thought of that in a zillion years. That's been one of the things holding me back from taking on a project like that. Every page I'd seen describing how people gashed their blanks looked noxious for one reason or another (especially since most of them required you to have a rotary stage already!) But I like the idea of drilling two offset bolt hole patterns. Do you have a closeup picture of the tooth profile? It looks quite clean. I'm curious how much backlash you'll have after you lap the worm to the wheel. Also, do you have a way to measure the regularity of the resulting worm-and- wheel? I'm just curious how it'll stack up against a commercial gear set. That's cool! Tom ------- Date: Sat, 11 Dec 2004 15:40:00 -0000 From: "vn1500g3" Subject: Change Gear Question on a Model 101.28990 Lathe [atlas_craftsman] Does anyone have any experiance or documentation on using change gears on a Craftsman under-drive lathe model 101.28990? What I'm looking for is a gear combination that would alow me to produce Metic threads if possible. Any information would be greatly appreciated. Thank you. ------- Date: Sat, 11 Dec 2004 20:33:20 -0000 From: "Rob Peterson" Subject: Re: Change Gear Question on a Model 101.28990 Lathe "David S." wrote: > I believe you would need to get a gear cluster for metric threading, and > install it the QC gear box. Try Clausing parts & service, Ebay or user > groups over in the UK for spares. Best of luck in your search. Here's probably the stupidest question on this subject. Even though the lathe has a QC box it still has a banjo bracket behind the gear cover. Couldn't someone just put in a metric gear set on the banjo and get metric threads? Rob P. who doesn't know squat about gearsets (or threading for that matter) ------- Date: Sat, 11 Dec 2004 13:14:38 -0800 From: "Glenn" Subject: Re: Re: Change Gear Question on a Model 101.28990 Lathe Yes, You can get very close approximations with transposing gears and the QC box. There is a table in the Atlas Manual of Lathe Operations and Machinst's Tables that spells it out rather nicely. To get true metric threads you would need a metric leadscrew. The page for metric threading was in the files section at one time as I uploaded it several years ago. You can't do all the metric threads with a single transposing setup though. You have to set the change gears for the specific thread you want and then set the QC levers to the correct position to go with it. You can't use the thread dial and you can't disengage the leadscrew or picking up the thread again would be very tedious. (like 127 turns of the spindle to get back to 0). And no it is not a stupid question :) It was actually the answer! HTH Glenn Neff Medford, OR ------- Date: Sat, 11 Dec 2004 22:28:57 -0000 From: "carbure2003" Subject: Re: Change Gear Question on a Model 101.28990 Lathe The table from the manual of lathe operation (1975 edition is posted in the file section of this group [atlas_craftsman]. Be careful as there is a typo mistake for metric pitch 2.5 mm. The correct combination of hand lever on the gear box should read A-7 Guy Cadrin ------- Date: Thu, 16 Dec 2004 00:51:21 -0000 From: "Ron OConnor" Subject: A question about a tap. [SHERLINE GROUP] I ordered a 2-56 2B H2 BOTTOM HI-SPIR FL STI TAP figuring it would be best for tapping a lot of holes in brass. The one I received seems to be somewhat larger than my other 2-56 taps and also will not thread into a 2-56 nut. The tap itself is marked 2-56 UNC. My question is: would this type of tap be slightly larger than a 'regular' tap? Do I need to use a slightly larger drill? Thanks in advance. Ron ------- Date: Wed, 15 Dec 2004 20:20:12 -0500 From: "Jerry G" Subject: Re: A question about a tap. Ron, Hold the phone! From your description, the tap you have is for "Helicoil" Inserts. The INSIDE of which is a 2-56 thread. (the inserts) That is why it will not thread into a standard nut. Mike up the OD. It should be from .081" to .086", if it was standard. The classification UNC refers to Unified National Coarse Thread Regards, Jerry G (Glickstein) ------- Date: Fri, 17 Dec 2004 00:09:15 -0000 From: "Ron OConnor" Subject: Re: A question about a tap. Of course I do. And who's fault is it? MINE! :) I went back and read the catalog and that's exactly what it says. In big letters too. Thanks for the reply, Jerry. Ron ------- Date: Thu, 16 Dec 2004 22:47:14 -0500 From: "Jerry G" Subject: Re: Re: A question about a tap. Ron, The recommended tap drill for a 2-56 Helicoil tap is 3/32" (.094"). I do not know your level of knowledge, so don't get insulted if I mention basic info. If you are going to drill in plastic, do you know that you have to "dull" the cutting edges of a twist drill, (a good honing stone to put a slight flat will do it) so it will not crack the plastic on breakthrough? If it is a blind hole, you still want a scraping action. Keep the RPM down and use a soapy water solution to keep the heat down so no melting occurs. If drilling through, use a back up piece under your work, like a piece of wood. This is true of both the drilling and the tapping. Have you ever used Helicoils? They are inserted with a special tool that drives the "tang" of the insert into the tapped hole. Depending on your application, sometimes the tang is then broken off. Helicoils and the proper usage can be a mini course in itself...... Regards, Jerry G (Glickstein) ------- Date: Sat, 29 Jan 2005 20:05:32 -0000 From: "timxdunn" Subject: Tapping drill rod [sherline group] Hello. This is not really a Sherline question but I know we have experts here that can help me. I am trying to tap 6-32 threads into the end of a piece of .25 dia drill rod. So far I have broken two taps, so now I figure it's time to ask for help! After refering to the machinery's handbook I increased the size of the drill from 0.106 to .116", apparently with thread engagement of 0.25" that is OK. It did seem to tap a little easier but still broke the tap. So, what is the secret? Do I need taps made of Unobtanium to tap drill rod or do I just need to be more careful? By the way, I was using plenty of lube (RapidTap) and I was backing the tap out a 1/2 turn after each 1/4 turn of cutting. Thanks in advance, Tim ------- Date: Sat, 29 Jan 2005 12:49:02 -0800 From: Alan Marconett Subject: Re: Tapping drill rod Hi Tim, are your taps dull? Or cheap imports? Just be careful. You don't say how you are tapping, tap in the tailstock? Turn the chuck BY HAND, leave the tailstock loose enough to be pulled along, or release the taper in the tailstock. After getting the tap started with a little tailstock pressure, you only want "guidance" from the tailstock, not a fight. This might get you going. Alan KM6VV ------- Date: Sat, 29 Jan 2005 15:48:58 -0500 From: "Jerry G" Subject: Re: Tapping drill rod Tim, first of all, be aware that 6-32 is a difficult thread to tap in any material because of the relative coarseness of the thread to the OD and root diameter. Second, drill rod can be difficult because it can work harden readily. Now, as to the correct tap drill size. If you look at a tap drill chart, the recommended drill for 6-32 is a #36 (.1065" diameter). That is for a thread engagement of 75%. This can be adjusted as you saw in Machinery's handbook. What kind of tap are you using? There are three basic taps. Taper (with the first six threads removed, sort of) Plug (with the first three threads removed, sort of) Bottoming (with the first thread removed, sort of). The tap you are using will have a direct effect on the breakage. The most common causes of tap breakage are: 1. Misalignment of the tap to the hole being tapped. 2. Chips wedging between the work and the tap. 3. Striking the bottom of the hole being tapped. The tapping is not a question of how many turns or what direction to relieve the cutting. It is a matter of feel. What size tap handle are you using? Are you hand tapping? Tapping in a drill press? How is the part held? In my fifty years of toolmaking, I have never heard of taps made of Unobtanium....:) Answer my questions and then I can help you... Regards, Jerry G (Glickstein) ------- Date: Sat, 29 Jan 2005 18:18:15 -0800 From: "Dave Hylands" Subject: RE: Re: Tapping drill rod Hi Tim, I've done a bunch of tapping using smaller taps (0-80 and 2-56) and I found that I really don't like taper taps. I mostly hand tap, and I find that the plug taps affer much less resistance than the taper taps. I noticed on the ends of my taper taps, that some of them have a larger cutting area. I'll also never use a Home Depot (or other hardware store) quality taps. After buying some good quality taps from a local machine shop supplier, I discovered that they cut with a lot less force than the cheap taps. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Date: Sat, 29 Jan 2005 21:14:14 -0000 From: "timxdunn" Subject: Re: Tapping drill rod Wow, I only went out to buy some more taps and there are all those replies already! Thanks everyone. To answer Jerry's questions: I was using a taper tap. I have just purchased two, USA made (Vermont), bottoming taps. I was hand tapping, but those days are over. I cannot explain why it did not occur to me to leave the part in the chuck and put the tap in the tailstock. I will try that next. I'll release the tailstock and turn the chuck by hand, as Allan suggests. Once again, thanks for the help. I'll let you know how it works out. Tim ------- Date: Sun, 30 Jan 2005 04:00:17 -0000 From: "timxdunn" Subject: Re: Tapping drill rod Dave, thanks for helping out. I bought a couple of bottoming taps from Orchard Supply (I really wanted them today). They were made by Vermont American. Anyway, with the help given by others earlier today and with my new taps, I was able to get the job done this afternoon. I put the tap in a drill chuck in the tail stock of the lathe and turned the chuck by hand. I also disconnected the drive belt from the pulleys to improve the feel. Probably the only smart thing I did today! I'll take your advice and buy some good quality taps for future use, and I think I'll avoid 6-32 where possible. I had got rather blase about my tapping ability having never broken a tap in the many 0-80 and 00-90 holes that I had tapped. I guess aluminum really is softer than drill rod! Thanks again to everyone that helped me out. I take my hat off to anyone that learned machining at home in the dark days before the internet. Tim ------- Date: Sun, 30 Jan 2005 15:52:36 -0000 From: "Chuck Fellows" Subject: Re: Tapping drill rod One further note to this thread... I use a 6-32 tap a lot and have found that spiral fluted taps work really well. Instead of creating chips, they create long curled swarf which is less likely to bind the tap. I also use a homemade tapping guide for all my tapping and it has reduced my tap breakage to zero. Chuck Fellows ------- Date: Thu, 03 Feb 2005 17:16:36 -0000 From: "azbruno" Subject: Re: threading cleanup after work is removed I've occasionally had to return a threaded part to the lathe to continue single point threading. I don't use standard sizes, and sometimes if things don't fit well I need to clean it up. I get the tool close to the work and then turn the spindle to get the half nuts enabled on a thread dial mark. I then work with both the cross slide and compound until I have the tool fitting right into the existing thread. When it's right, I can move the compound in and out and see it aligned with the angle of the thread. I then zero out the cross slide DI that I have attached (I don't use the lathe's cross slide dial). Works every time... no harder than dialing in on a 4-jaw chuck. I've done this on internal threads too, but it's not so easy when it's hard to see in the bore. Bruno ------- Date: Mon, 07 Feb 2005 03:52:01 -0000 From: "karlw144" Subject: nut/shaft sizes [atlas_craftsman group] Not exactly about atlas lathes, but as part of the dividing head I'm making, I need two jam nuts on a shaft. The nuts are 1 1/16" 24 and 1" 24. The shaft, of course has 1 1/16" 24 and 1" 24 threads; in between the nuts the shaft has to be 1.000+.000,-.0005 for a pilot for a gear. I used the formulas in Sherlines book and looked at the stuff in Machinist Handbook. Made the nuts first (single point cut) so I could fit them to the shaft as I single point cut the threads on the shaft. I don't know what I did wrong, BUT, the 1 1/16" nut won't quite clear the 1.000 gear pilot,and the 1" nut is also on the small size, won't thread on either. For the 1" nut I started with a .928 hole and cut the threads .026 deep on the compoud set at 29.5 degrees, for the 1 1/16" nut I used .990 hole and again .026 deep. Where did I go wrong?? thanks for any help, karl ------- Date: Sun, 6 Feb 2005 23:15:36 -0500 From: "rigrac" Subject: Re: nut/shaft sizes Karl: My Machinery's Handbook says Minor Diameter on 1"-24 TPI is .955 to .965 and although it does not have Minor Diameters for 1-1/16"-24TPI it does have for 1-1/16"-20 TPI which is 1.008 to 1.020 and 1-1/16"-28 TPI which is 1.024 to 1.032. Something is wrong with your figures. Basic Minor Diameter for Internal Threads is Basic Major Diameter minus 1/ Number of Threads per Inch which is 1.062 minus 1/24 which is 1.062 minus .042=1.020 Ron ------- Date: Mon, 07 Feb 2005 21:33:45 -0000 From: "karlw144" Subject: nut/shaft fits Thanks for all who got back to me. I found my error. I subtracted 2 times the thread depth from the nominal diameter to arrive at the dimension for the bore.. I used the wrong thread depth from the table. I chucked the nuts up, opened both nuts up to spec, and VERY carefully picked up the threads and recut them to the proper depth. I got a very good fit to the shaft. I checked every couple of thous until they went together. About every other cut, I re-cut without changing any settings. Worked like a charm. thanks, karl ------- Date: Thu, 17 Feb 2005 23:04:39 EST From: n8as1x~xxaol.com Subject: threading -techniques history exposition [atlas_craftsman] FWIW ...thrdng originally done w/ tool rest & hand gravers (a la wood lathe ) ...thrd was drawn on bar & hand held tool scraped to the line..successive passes corrected/deepened ,w/ scrape cuts of tenths...parallel lines to the cut kept one on track ...i have tried it! ( nuf said) ....& a century or so ago , there were men who cud still accomplish the task ... somewhere around 1780 ( dont hold me exact on dates, pls.) maudsly had a screw cutting lathe (leadscrew /carriage)..no compound yet...so thrding was w/ cross feed .....& was done this way for more than a 100 yrs.....coarse thrds were a problem w/ chatter & rough finish due to large area of tool engagement & lack of rake,since pos. rake affects the cutting angle the more rake,the more acute the angle (course w/out standardization, u used whatever suited for an angle.)...problem was alleviated by either roughing /hogging out w/ plenty back rake & finishing w/zero rake bit in a flexible (gooseneck shaped) holder w/light cuts,cleaning up the flanks as the thrd was finished, or using the gooseneck tool all the way w/ moderated cut depth & slo speed, tool bit flexing downward out of the way as it hit hard spots , eliminating chatter...since slides had NO DIALS, returning x/slide to zero & adding just a few thou for next cut was problem, since zero was where? & constantly changing..so crossfeed screw stops were used ,clamped to slide . to return you....( & they are still handy to keep u from missing the zero on a dial by one revolution, particularly w/ a lot of slop in screw( think abt how i know that) ... somewhere around 1885 , ( my circa 1895 Reed 14 in , was factory sans compound , just finished making a vertical dovetailed side saddle compound for it ,there being only 1 1/4 in from tool slot to centerline) , compounds appeared allowing (when set at 30deg,or tad less)a bit w/SIDE RAKE only,since it is cutting on the left flank only ....w/ a 60deg. bit & TRUE 30deg. compound,the rt. flank does not cut ......at 29 1/2deg, it barely takes a cut .,( at 30 + deg., u get a non stndrd thrd form) ......result is a smooth thrd w/ out needing rough /finish bits & w/ dials also , much faster..... BUT ,reasonably smooth thrds can still be done w/feeding straight in ,by reducing speed & taking minimal cuts...just use a grease pencil mark on dial after each cut ,if u dont have a stop (course if working commercial, costs are prohibitive working so slowly)...last internal 8 pitch thrd i cut was w/ cross slide only , & it was quite acceptable ..... gooseneck tool holder is fascinating to watch ...i purposely chucked up a bar .020 tir, & put the cutoff tool (gooseneck) to it ..it flexed as much as 1/8 in as it cut w/ out chatter, the flexing breaking up the resonance( & not cutting as much at the flex, giving an inaccuracy, which made no difference since a cutoff was in progress ....,also so if roughing.....for finish work , wud take only LIGHT cuts for accuracy sake...but then again , 80+ yrs ago ,one routinely finished couple thou over & took file /cloth to part .(another area where skill is involved to retain "truth".. hope this has been of some interest to newer hands, & may have clarified some issues best wishes docn8as ------- Date: Sat, 26 Feb 2005 20:59:49 -0000 From: "daves_cycle_and_engine" Subject: Re: single point thread cutting [atlas_craftsman group] > I didn't know that there is a "new" way of cutting threads, single > point. What is the advantage of feeding the tool in at 90 degrees? Do > you still use the cross as the reference slide and the compound as the > feeding slide? Do you grind the tool bit differently? > BTW: I use the chart in the Atlas' manual of lathe operation for the > depth of thread to get close, then carefully refining the cuts until the > mating thread fits. Leo (pearland, tx) Well I don't know if it is "newer" but feeding the tool straight in is the "other, not recommended" way of doing it. When I worked professionally as a machinist, most of our work was 6061 aluminum with some 303 SS thrown in. With a good industrial grade lathe and easy to machine material, you can cut "go/no go" gauge quality threads feeding straight in all day long. However, it does not work very well in hard to machine material. They should be done the "proper" or recommended way. The advantage of feeding straight in is that it is very fast. You only have to deal with one handwheel (the cross feed). There is no "turn this hand wheel" then "turn that hand wheel" and back & forth. Get distracted and get the handwheels "out of synch" and you wipe out the part. Just zero the cutter on the OD of the thread and feed in to the depth of the thread (taking several passes until you get to full depth of course). Get close to full depth and "fine tune" the depth as with any thread cutting. Yes, the tool bit is ground differently. Thanks for your reply. Dave ------- Date: Sat, 26 Feb 2005 16:15:10 EST From: n8as1x~xxaol.com Subject: Re: single point thread cutting > I didn't know that there is a "new" way of cutting threads, single > point. What is the advantage of feeding the tool in at 90 degrees? feeding striaght in is the "old "way of feeding ,before there were compounds ,which first appeared near 1885 ..... thrd cud be roughed in w/ plenty back rake on bit, then finished w/ a zero rake bit , since back rake changes the 60 deg. angle to more acute...also flex(gooseneck tools/holders were used to mitigate chatter w/ deeper cuts, since both sides of tool were cutting ...........compound allows SIDE rake ,easing cut, since only left edge cuts much...cutting straight in is easier w/ a x/feed stop since zero changes w/ each cut ( so u dont HOG a cut ), grease pencil works as well ... havent noticed drunken thrds on my 14 in Reed lathe , but it weighs maybe 1800 lbs ,& has a massive carriage , being over 100 yrs old ....cut some 1 1/2 x8 thrds for a faceplate on crftsmn12x36 w/out any APPARANT drunken thrds ,but i keep the lathe fairly tight ...am sure it CAN happen ... best wishes docn8as ------- Date: Sat, 26 Feb 2005 16:13:14 -0500 From: "rigrac" Subject: Re: Re: single point thread cutting Been a professional Machinist for 30 yrs and have cut 98% of the threads I have cut both at work and at home using the Straight Feed In Method. This applies to both Internal and External Threads. Other 2% came from time spent learning to do it with compound set over while serving my apprenticeship. Also tool is NOT ground any differently. Still a 60 Degree included angle for United National Thread Pitch Form whether feeding straight in or at 29-1/2 Degrees with Compound. Ron ------- Date: Sat, 26 Feb 2005 16:20:18 EST From: n8as1x~xxaol.com Subject: Re: Re: single point thread cutting > Also tool is NOT ground any > differently. Still a 60 Degree included angle for United National ...if u dont use side rake on tool when using a compound , a fair part of real value of compound thrdng is lost......yes , u only have left edge doing serious cut , but u are making it harder ,on steel/alum, by not using normal side rake......course carbide is another story , tho w/ light machines , i still want some rake . best wishes' docn8as ------- Date: Wed, 09 Mar 2005 12:20:16 -0600 From: Jon Elson Subject: Re: cross feed screw [atlas_craftsman group] Jim Russell wrote: >Has anyone made a cross feed screw from acme thread stock? I have >a lot of play in the cross feed on my Craftsman/Atlas 12 x 48 and it >seems to be caused more by a worn shaft than a worn nut. When I >screw the cross feed to its' extremes, it's tight so I think my nut >is O.K. The screws I have seen for sale are all used, so I hate to >take a chance on them. Any thoughts will be appreciated. I made one from steel shaft. Remember this screw is LEFT hand! I was quite embarrassed when I got it on the lathe and suddenly discovered I'd made it backwards! But, it was a great screw and nut, with a really close fit all the way. The nut is MUCH harder to make than the screw. Having most of the wear in the middle of the screw is the classic wear pattern, especially if the nuts are bronze. (But, I'm pretty sure Atlas nuts are brass.) Since you need to fit the nut and screw, I'd make another nut while I was at it. Make the screw first (remember to put the undercut at the beginning of the thread so you just run off the thread when pulling the slide towards you, instead of binding up) and clean up the rough edges of the thread with a little file. Then, you can make the nut, and fit it every pass until it just slips onto the screw. Jon ------- Date: Thu, 10 Mar 2005 14:41:25 -0000 From: "pbbid" Subject: Re: Feed screws I have used acme rod for this. The first thing I did was make a tap from a piece of the left hand acme rod. (i.e. tapered it on the lathe, cut some relief flutes on the mill, filed wrench flats on the other end, hardenend with Kasenit and a torch - a 40 minute job. Then rough out the internal thread of the brass nut with a single point tool - form not too critical. Use the tap you made to clean out the rough threaded nut. In making the new screw I parted the old acme section from the old screw and spliced on a section of the new acme stock. That prevents having to make a whole new screw with the keyway, fine threaded section, bearing section, etc. Worked great and was easy. ------- Date: Wed, 9 Mar 2005 18:27:43 EST From: n8as1x~xxaol.com Subject: Re: cross feed screw > made one from steel shaft. Remember this screw is LEFT hand! I was > quite embarrassed when I got it on the lathe and suddenly discovered I'd > made it backwards! ... Jon did the same thing w/ first sq. thrd i cut , a nut for compound of antique lathe ...pathetic !! .........one thot : maybe just take a cleanup cut on the screw ,truing it ,& make a new nut (or jb weld new thrds in it) u now have an undersize screw/nut (few thou. ) but so what ...u were going to pitch it anyway .....i recently cut a 10 pitch 1/2 in acme thrd for a compound i made for an antique 14 in lathe , & it really was a piece of cake ...hate to say that , but i ground an undersize bit to the accurate side angles , set the compound parallel to lathe axis , cut w/ the x/slide only to CORRECT DEPTH (remember clearance at depth) ..then took one/two thou .side cuts w/ compound till i had the fit i needed........this took out the fear of o/size due to too large a nose on bit , & cleaned up the sides of thrd (brass cut very clean w/x/slide thrdng)...i used an acme thrd ga. , but cud as easily used the screw itself , or a good end on a used screw.........i "dogged " it w/ much trepedition for a few weeks !!!.....finally just cut it & it was quick & easy .........just use a x/slide stop or grease pencil on dial to keep track of where u are , so u dont get lost returning the x/slide , & "HOG " a cut .........i have cut acme /sq. thrds this way ever since doug king posted this method (old Brit way ...had read abt it in texts, but not used it ) .....takes the worry out of getting a bit ground dead on.. (Acme SIDES must be to spec, but that is more easily seen when gaging.) best wishes docn8as ------ Date: Sat, 12 Mar 2005 22:48:25 -1000 (HST) From: benedict-listx~xxhawaii.rr.com Subject: Re: Re: Interesting way to power a Taig lathe [taigtools group] [NOTE TO FILE: Original conversation was on the subject of using the motor from a small drill press to power a Taig lathe, and then using most of the remainder to make a tapping stand. See also the Taig Mods General file.] In taigtoolsx~xxyahoogroups.com, Gene Furrwrote: >>The best part of that is what you have left, makes one great tapping >>machine. Just move the handles to the top spindle and take the spring out. >>I cut the handles from the gear and bored a hole that fit the spindle in >>place of the pulley. put the gear back in the frame, removing the spring so >>the spindle can fall down. The little knob that was used to hold the belt >>tight is put in place of the allen screw on the right side to hole the >>spindle up when you are getting ready to put your tap in. Never broke a tap >>or started one out of alignment since I fixed it. On Sun, 13 Mar 2005, dkp_design wrote: > Now that's an AWESOME Idea. I've been banging my head here trying > to figure out how I'm gona tap 2.5mm holes true and safely on edge > of 6mm pieces. I've broken so many taps and ruined pieces that it's > about to make me give up. I'm gonna look in the Pawn shops for old > drill press' Thx for the idea I'll throw out another idea here, just in case anyone doesn't have room for another drill press in their shop: When I first started doing machining the guy who was teaching me showed me a neat trick for not breaking taps. I got a squared up block of aluminum about 3/4" thick (give or take) and drilled a hole in it slightly larger than the size of the shank on the tap I was using. Put the tap through the hole, put the block on the work to be tapped, and the tap enters the work dead square (well... as dead-square as your holes are drilled through the block.) The same kind of idea can be used to tap radial holes in cylinders, too. A part I made for work was a cylinder about 1.5m high and 1.2m wide. It needed 32 holes drilled and tapped M3 around the top and bottom. I made a little fixture that looked kinda like a sine bar with two holes drilled through it midway between the two rolls, one the size of the tap drill, the other the size of the tap shank. Once the locations were marked on the part, the jig was held up against the work with the rolls bearing on the surface of the cylinder. The first hole in the fixture held the drill straight so the holes could be pistol-drilled. Then the fixture was flipped over and the holes were tapped using the hole in the fixture sized for the tap shank. 64 blind holes drilled and tapped with no snappage. I've still got that original tap block I made. It's got scads of holes in it now. It's just a matter of grabbing the tap I'm going to use and trying the holes to see which one fits the best. If I can't find one that's close it's time for a new hole. Don't get me wrong... I like the idea of turning a drill press into a tapping machine. The same shop where I made that tapping block had a really nice tapping machine. Given the choice I'd have both setups. Tom ------- Subject: Re: how to do it ? [Oldtools list] From: Jim Thompson Date: Sun, 27 Mar 2005 15:35:02 -0800 When I was working I carried a full set of 8 point sockets to use on taps and other square ended tools. The smallest one is about 3/16" and the largest is an inch as I recall. I haven't looked at them for a long time. There are various sizes in 1/4", 3/8", and 1/2" drives. Any time you have need to drive anything with a square end, an 8 point socket is just the ticket. Look in the fleas, there should be lots of them in the piles of old sockets. ------- Date: Tue, 29 Mar 2005 21:50:35 -0600 From: Jon Elson Subject: Re: Damaged Spindle Threads-Chuck Wobbles. Help! [atlas_craftsman] oakdaleaircraft wrote: >After inspecting the threads, I noticed the first thread (at the end >of the shaft) has a small section that looks like it's been bent in a >little bit. It appears that this is cocking the chuck to one side so >it does not spin straight. Take a magic marker and paint it on the threads in the suspect area. Wait a minute or two for it to dry, then put the chuck on and back off. The marker will be wiped off the area where the binding is. File this area gently with a triangular file. After a bit, repaint and try again. When you get it sufficiently filed down, it won't cock the threads of the chuck, but will still be generally supporting the threads. Jon ------- Date: Tue, 29 Mar 2005 22:08:53 -0600 From: "jerdal" Subject: Re: Damaged Spindle Threads-Chuck wobbles. Help! Something sounds wrong here......if teh chuck bottoms flat, it should be straight, and no way 0.125 off radially. Does it bottom on the shoulder of the spindle? Without any light seen under it? If so, it HAS to be straight, and can't be off that much radially. Maybe you never get it down tight. The suggestion of marker and checking the wear spots is good. I would add marking the back of the chuck on the part that contacts the spindle at rear, and verifying that it gets evenly rubbed off there. A thread file, or a three-corner file will fix it. I'd put a piece of thin brass or the like between the 3-corner file if you use one, and the good thread on the other side of the thread groove, to avoid cutting a notch in that thread. A thread file will re-form the thread by shaving off anything that fills in the thread groove. But it won't cut any extra due to the way it's made. May be hard to find in 8 tpi. JT. ------- Date: Tue, 29 Mar 2005 23:32:33 EST From: catboat15x~xxaol.com Subject: Re: Digest Number 2287 > Does anyone have any ideas as to what I can do to correct the > problem? I've heard of people taking a dremel to the damaged thread > area and grinding it off. Before starting to grind away on a spindle, check the problem carefully. The fit of a chuck on our lathes depends more on the fit of the back plate recess to the spindle register (the larger diameter part in back of the threads). The recess in the chuck should fit the diameter and butt against the register. Look for swarf or something interfering with that fit. Go around the inside of the recess in the chuck mounting plate or body and the register diameter and front with something like a sharp scriber point. (Not hard enough to scratch the metal, just to feel for a chip imbedded someplace.) A chunk of swarf can be hard to see visually as it may have been crushed and the color is about the same as the base metal. (That was how I finally found a small chip imbedded in the gear that engages the rack and had my saddle locked up. Using a scriber to check each tooth root.) The threads serve mainly to pull the chuck into the fit of the register and hold it there. Only then would I think about fixing the spindle thread and in that case would try to set up the change gears for that thread and a 60 degree threading tool and clean up the existing thread rather than attack the thread with a hand held grinder. I would turn the lathe by hand to make sure your threading tool is really following the existing good part of the thread before putting any power to the cut. After fixing what ever problem you have there it would be a good idea and an exercise in internal thread cutting to make up a protective nose piece if you often use the lathe with collets or without something screwed onto the nose of the spindle. John Meacham in the high desert of California 12 inch Atlas, Minimill, HF bandsaw, rusty file ------- NOTE TO FILE: Maybe the best solution is a combination of the suggestions Jon, JT, and John made depending on your level of skill and the tools you have on hand. After first protecting the good thread areas, careful use of a 60 degree file (sneak up on the fit slowly) will likely solve this situation. Proper use of files is a valuable skill that would have been learned by early machine apprentices before ever getting near a lathe. When doing any thread chasing (trying to clean up or deepen existing theads) with a lathe, wise users prudently verify the cutter is truly registered with the the existing thread before proceeding; it is generally easy (lathe unplugged first) to then turn the lathe by hand to accomplish the small amount of cutting needed. And then make a thread protector per John's suggestion. ------- From: "Matthew Patton" Date: Mon Apr 18, 2005 Subject: how best to split round/square stock in 1/2? [sherline] I'm not doing so hot in the tapping by hand department. Not sure why but I can never seem to get a tap to run true. And the bigger the tap, the more obvious the problem. So while I will likely rig up a simple shaft for the T-handle to ride in the head stock like somebody else posted a while back, I'm toying with the notion of taking some 1/2" round or square bar and making something that will fit into a 3/8's mill holder. The easiest way I know of to cut opposing 45deg V-channels (to hold the square end of the tap) is to split the stock and run the milling head at a 45deg angle. And to split the stock without losing a ton of material requires a slitting saw. Am I on the right track? Or is there a much better way to go about this whole exercise? ------- From: Dave Hylands Date: Tue Apr 19, 2005 Subject: Re: how best to split round/square stock in 1/2? > I'm not doing so hot in the tapping by hand department. Here's a rather interesting tapping guide: http://groups.yahoo.com/group/hintstips/files/Hints/2797-TappingGuide.pdf You may need to join the Yahoo group http://groups.yahoo.com/group/hintstips/ if you aren't already a member. Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- From: "Jerry G" Date: Tue Apr 19, 2005 3:38 am Subject: Re: how best to split round/square stock in 1/2? Suggestions: Don't go through all that. 1. A simple pin (3/8" .375" to fit in the end mill holder) that is pointed to match the center hole of a tapping handle will do the job. 2. If you must make the adapter, get a square broach.... 3. Or, for a more ambitious project, make your self a little tapping stand. 4. Or buy one.... Grizzly has one for about $75.00 G8748....Amazon is selling it.... I have no commercial connection with Grizzly.... or Amazon... just a satisfied customer... If you run the head at a 45 degree angle, you will have to "tram it" when you want to square it away for normal use. Regards, Jerry G (Glickstein) P.S. BTW, I hold the world record for largest tap ever broken by hand... (indoors) It was a 7/8"-9. ------- Date: Sat, 21 May 2005 13:50:48 +0100 From: Clive Foster Subject: Re: Threading Question, Math-less method [taigtools] Wayne, this is the math-less threading method for lathes with both cross & top slides as a step-by-step procedure:- 1) Mount work and turn to correct OD for thread. 2) Set top slide at an angle about 2 or 3 degrees less than the included angle of the thread. 3) Mount suitable threading tool on centre height and at 90 degrees to work. 4) Set top slide so that it is well engaged on the dovetail slide but still has sufficient travel to cut thread. 5) Using the cross-slide bring the tool up to firmly touch the work. 6) Set cross-slide and top-slide index dials to zero. 7) Move saddle along bed to clear the work. 8) Feed cross-slide forwards by the depth of thread to be cut (as given in standard reference tables e.g. Zeus books). 9) Set cross-slide index to zero. 10) Use top-slide to withdraw tool so it clears the work OD. 11) Move saddle so that the tool can reach the work. 12) Use top-slide to move tool forwards until it touches the work and note index reading. 13) Move saddle so that tool is clear of work. 14) Set top-slide to previously noted index reading and and add first cut. 15) Make threading cut. 16) Withdraw tool using cross-slide. 17) Move saddle to take tool clear of work. 18) Return cross-slide to zero setting. 19) Apply next cut using top-slide. 20) Repeat steps 15 to 19 using appropriate depths of cut until top-slide reads zero. 21) Make last cut and spring [no-feed] cuts with top-slide at zero. Nice thing about this method is that the only important settings are both zero. Its even easier if you have a cross-slide bed stop 'cos you can use that instead of carefully running up to zero before each cut. Neatly gets round the big disadvantage of the simple angular feed method which requires you to calculate the actual tool feed to give the right depth of cut using trigonometry. Also works fine with internal threads but that takes more thought and attention. Clive ------- Date: Tue, 14 Jun 2005 20:58:50 -0500 From: "Charles & Dorothy Brumbelow" Subject: Re: Re: Thread/Drill Charts in pdf? [atlas618lathe group] Here's a site with the information.... http://www.efunda.com/DesignStandards/screws/tapdrill.cfm and another variation +/- items from the first one: http://www.engineersedge.com/tap_drill_chart.htm and still another variation: http://www.smithfast.com/tapdrill.htm This one has a simple formula for calculating tap drill size: http://www.metal-mart.com/Guides/Tap_Drill_Sizes.htm I'm sure there are others.... Let me know if you want me to convert one of these to PDF. (In fact I've converted the first one to PDF and will post it in the group's file section.) Charles ------- Date: Mon, 12 Sep 2005 12:22:47 +0000 From: eeengineerx~xxcomcast.net Subject: Re: differential screw [beginnerswkshp group] > Can anyone point me at a good www description of how a differential > screw (for fine adjustment) works and how it is 'constructed'. Consider a 32 tpi thread. This has a pitch of 0.03125" per turn. Now consider 40 tpi thread. This has a pitch of 0.025" per turn. The dif- ference betwenn the two is 0.00625". ( equivalent to a 160 tpi thread) If you arrange to screw one thread in while the other is screwing out the net movement is the difference between the two pitches. This usually requires a set of gears turning the two screws at the same time. One of the gears may need to be a long pinion to accomodate the movements. You will have the backlash from two threads to deal with. Jim B. ------- Date: Mon, 12 Sep 2005 13:34:19 -0400 From: Donald Qualls Subject: Re: differential screw One relatively simple way to avoid the (still further) backlash and slop of gears and linkages -- make the two threads concentric. If you have a threaded tube running in a fixed brace, and inside that an opposite thread (i.e. advances other direction with same rotation) with different pitch, then a rod that threads to the inside will advance at the differential of the two threads when the tube is rotated (potentially, with a simple pulley or gear on the end opposite where the output rod emerges). This setup is very compact (hardly larger than a simple lead screw), has no slop between the two screws (since they're part of the same rigid unit), and is mechanically easy to drive, even at high speed for rapid positioning if necessary. Use lapped threads inside and out, and thread backlash can be reduced considerably; more so with a preload that ensures the remaining backlash is always taken up in one direction (if extreme accuracy is required). Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com ------- Date: Sat, 19 Nov 2005 21:50:59 -0000 From: "Dave Miller" Subject: Tapping Stainless I'm having some trouble with work hardening while tapping some 4xx series Stainless. It's about an inch thick, open hole drilled with a 29/64 drill on the lathe and then with tap handle and 1/2-20 tap in the vise. I'm using Kerosene/ATF about 50/50. At about 3/4 of the way through, the tap started barking and getting difficult to turn. Then, of course, it snapped up at the square drive. Am I moving too fast? Incorrect lube? It was a starting tap of good quality, HSS. Is there a way to finish this hole and avoid this problem on the other 6? dave miller deltona, florida ------- Date: Sat, 19 Nov 2005 22:25:57 +0000 From: "jo barden" Subject: RE: Tapping Stainless Hi Dave, tapping stainless can be a real bugger. The work hardening can be a major problem, if possible I would try to aneal, or rather than using preferred tapping size try a little bigger drill bit or ream to achieve a slightly larger than normal tapping size and go carefully. Sorry for not being much help. Jo ------- Date: Sun, 20 Nov 2005 00:02:44 -0000 From: "Dave Miller" Subject: Re: Tapping Stainless Thanks Jo, I was wondering if I could try to aneal it. I did quite a bit of machining in the lathe and it cut great with just a sharp HSS bit. It even drilled great, but the tapping was the downfall. I thought about going a little larger on the hole and I don't need full thread purchase; I'll try that with the other holes. dave ------- Date: Sat, 19 Nov 2005 18:48:55 -0600 From: Jon Elson Subject: Re: Tapping Stainless A plain HSS tap may not be able to handle this material well. When some stainless steels work harden, they are getting close to HSS hardness, and will wipe out the edge of a tap on the first hole. A coated tap may be the thing you need to use. If you don't need the maximum thread strength, drilling the hole just a few thousandths larger can greatly reduce the load on the tap. A tapping fluid made specifically for SS may be a big help, but any thread cutting oil will have something in it for preserving the cutting edge. Tapping 1/2" holes one inch deep in SS is tough going even with the very best tooling for the job. A plain HSS tap and improvised cutting fluid is going to make it practically impossible. Jon ------- Date: Sat, 19 Nov 2005 18:50:56 -0600 From: Jon Elson Subject: Re: Tapping Stainless Bob May wrote: >>Don't try to do the whole tapping operation at one time. Back off and do another hole, making sure that the tap is cooled completely before starting the second hole. The tap is heating up and rubbing the sides of the hole harder and that is work hardening the stainless. You almost want toflood the hole while tapping to keep the temp of the tap down. The barking is from stick-slip friction of the tap against the stainless and must be avoided at all costs. << Yes, and I think his improvised cutting fluid is really making it worse. The high pressure additives in real cutting oil really show their merit on these hard cases. Jon ------- Date: Sat, 19 Nov 2005 17:22:18 -0800 (PST) From: James Sterner Subject: Re: Tapping Stainless Hi Dave: You must use very sharp drill bits, and drill the hole all the way through or to the proper depth in one shot without hesitating. If you get that correctly done a new, very sharp tap by hand should work. Dull tools or even hesitating just a bit (don't let the bit linger too long in the hole either) will cause a hard spot, and some stainless will work harden harder than tool steel. A piece of stainless I drilled with a dull bit tore up a few brand new drills to finish the hole, I almost thought it was a lost cause but good thing I didn't have to tap it! Jim ------- Date: Mon, 21 Nov 2005 20:52:00 -0800 (PST) From: Tom Johns Subject: Re Tapping Stainless Hi Dave: I have been working stainless since 1974 when I went to work for the shipyard. I'm still working there today and we build custom boats any size the customer wants. You can check out: www.littlehoquiamshipyard.com if you want to see some of our work. When I first started drilling & tapping stainless, I was having the same troubles you are. Then I run across a tapping fluid named Microfinish that changed everything. It was a honey colored fluid and was about as viscous as warm honey. It broke down the molecular adhesion between the drill or tap and the stainless and made the tools last much longer. Then a few years later, I couldn't find it anymore. Then I discovered that Union Butterfield had the same stuff called cutting fluid. Then just recently I couldn't get that anymore. But now CRC has it and it is called HD Tapping fluid and you can get it from McMaster Carr. Once you use this stuff, you won't even consider anything else. Stainless is a stringy metal; I call it that not having a better word for it. When you drill it, you have to keep enough pressure on the drill bit to make it cut. If you don't, it will just harden the metal and dull your bit. The bit must be sharp to start with. The best taps I have found to use are called gun taps, or spiral point taps. You can run them thru without having to back them out and they push the chips out ahead, which is ideal for your thru holes. Use of a coated tap also helps. I use the steam oxide taps from J&L. They are black and you can tap many holes in stainless with them. I hope this will help you. Stainless isn't so hard to work with if you use the right tools and fluids. Tom ------- Date: Wed, 23 Nov 2005 19:57:33 -0800 (PST) From: Tom Johns Subject: Cutting fluid for stainless I found where you can get the CRC true-tap HD cutting fluid. http://www1.mscdirect.com/CGI/NNLMIP?PMMANF=03400 MSC Industrial Supply Co. 1-800-645-7270 I can't understand why this is so hard to find. But it is the best working cutting fluid I have ever found. Tom ------- Date: Sun, 11 Dec 2005 09:01:07 -0500 From: Ron Ginger Subject: Re:Tapping methods [Min_Int_Comb_Eng] > I've started my first engine model, a Bob Shores Golden Eagle. I'm > familiar with tapping fluids, breaking the chip frequently and backing > out, but I'm concerned about using 2-56 and 1-72 taps. What are the > best procedures to minimize breakage and ensure success with these > small taps? NEVER hold a tap freehand. Use either the drill press or mill at the same setting you used to drill the hole. This will ensure the tap is centered in the hole, and more important- perpendicular to the work. I have never 'twisted' off a tap, I have 'bent' many. I often just put the tap in the drill chuck and then turn the spindle by hand. For 4-40 and larger I will run them inwith the variable speed control on my VFD. I almost always back out even 2-56 and 1-72 under power. Love that VFD! I have also turned the top of my tap wrenches to a nice 1/2" dia, then I can pull my mill collet down over the top of the wrench to guide it- you dont tighten the collet, just let it hold the tap wrench straight. Ive also seen spring loaded centers to put in the mill that bear on the top of the tap wrench- most have a center hole for that. Ive just tapped almost 100 2-56 bolts into a locomotive model, and broke one tap when I had the stock off-angle in the vise. ron ginger ------- Date: Sun, 11 Dec 2005 14:48:57 +0000 From: Brian Perkins Subject: Re: Tapping methods Pete: My favourite method is to hold the tap in a pin chuck which is then held but allowed to turn freely in the chuck of my bench drill. This keeps the tap vertical and prevents any bending which is the main cause of tap breakages. The pin chuck can then be held between thumb and forefinger which gives a very sensitive feel as to what is happening with the tap. Using this method I have successfully tapped over 600-12 ba(.05 dia.) holes and 128-14 ba (.04 dia) in my Hydra model at the expense of one 12 ba tap. Brian Perkins Bristol, England ------- Date: Sun, 11 Dec 2005 18:09:09 -0000 From: "buffaloman97405" Subject: Re: Tapping methods These are normal taps for me as a professional model builder. I often use much smaller taps, 00-90, 000-120 etc. Morris makes a tap and die holder for their 00-90 thru 2-56 tasps and dies. The dies and taps are held in place in little collet type holder by a set screw. The handle is very well built and very accurate. Although I mostly tap by hand I often tap by home made guide for precision demands. I bought an extra Morris handle and set serewed in piece of close fit drill rod in the chuck end of the holder handle. Then held it in my lathe in a collet. I then turned the handle knurls off and the handle down to 1/4". Then I turned a 5/8" diameter by four inches long rod down to 1/2' on one end so that it can be held in a drill chuck. The other end is drilled and reamed out to a nice slip fit to the 1/4' handle. Mount the holder in the drill chuck and then slip the handle up in to the holder. By positioning the drill or mill quill down to near the work surface and locking it you can now, by hand, turn in the tap to the hole being tapped by hand. Some people turn a larger knurled ring to fit over the handle to give more leverage in turning the tap. I think that gives too much leverage and leads to breakage. Tapping with these small taps requires as large a tap drill as allowable, lots of tap cutting fluid, and lots of in and out turns. I rarely go more than a quarter turn in before backing out. It takes lots fo patience. Especially when tapping brass or copper. The most likely place you will break a tap is as it is just breaking through the bottom of the hole. Bill ------- Date: Sun, 11 Dec 2005 20:35:08 -0000 From: "Philip Burman" Subject: Re:Tapping methods Hi Ron: With the method you describe, with the tap gripped in the chuck, how do you ensure that the tap feeds into the work piece at the correct rate. I must be missing the point somewhere. Best Regards Phil Burman ------- Date: Mon, 12 Dec 2005 08:15:52 +1000 From: "Ron Chernich" Subject: RE: Re:Tapping methods My .20 worth for using small taps without tears: Select a tapping drill size that gives about 75% engagement (NOT the minor thread diameter which some charts show). As Ron Ginger said, use your drill press (mill, whatever) to tap immediately after drilling (ie, same position) to start the tap exactly centered and perfectly vertical. Just chuck the tap, apply gentle down-pressure, and rotate the chuck by hand for a few turns. Running in under power is for experts. Don't try that yet. I like to clamp up the work for drilling as this ensures the tap will go in precisely the right place. I generally release the tap from the chuck after it is firmly started in the hole and finish off with a small, sensitive tap handle. An arrangement like Brian described is even better. "General" makes a commercial tap holder with a sliding, axial pivot pin in the end. The pin goes in the chuck and guides and aligns the holder. But I find my limited quill movement seldom lets me use the damn thing. Using a commercial tapping fluid seems to be better than using the appropriate cutting fluid. I have some from Devcon that is not awful. If your tap is new and sharp, you'll have no trouble. Small tap handles give more tactile feedback, and if you watch the tap, you'll see when it is twisting under too much torque. Develop your own feel for how often to back off the tap to break the chips. Buy "second" and "bottoming" tap pairs, and use them in that order. Model Engineers frequently have to make shallow blond tapped holes. I find the amount of taper on a "first" means the tap bottoms in these before it has cut a decent thread and you are in danger of just breaking away the shallow thread to the top of the hole with it. Ron #2. ------- Date: Mon, 12 Dec 2005 00:45:40 +0200 From: "Frank Hasieber" Subject: RE: Re:Tapping methods Best of all if you can get them are "serial taps" they are more expensive but work just great. Frank. ------- Date: Sun, 11 Dec 2005 15:31:05 -0800 From: "Carl Carlsen" Subject: RE: Re:Tapping methods Ron has great suggestions. Ron mentions >Small tap handles give more tactile feedback There are two designs that I use. One is on Bob Shores 'list' of good ideas and is just a round piece of aluminum, perhaps 1/4" thick and maybe 1-1/2" diameter, knurled around the outside, hole in the center for the tap and a long set screw to hold it. I made myself what looks like a small drill chuck with 4 set screws to hold the tap, I have a 1/4 x 2" shank on it to stick it up in my spindle, collet or whatever to keep it straight with the hole. Either method will give you great 'feel control' of what is happening. If you can't turn the tap with your thumb and one finger, there is something wrong and you had better remedy it before you break the tap! I'd guess the two main reasons for breaking a tap are ... not starting the tap straight or a dull tap! Carl ------- Date: Mon, 12 Dec 2005 00:32:05 -0000 From: "garyp3202" Subject: taps Never,never,never try to get away with using a dull tap. I've bored and tapped hundreds of 2/56 and 4/40 holes, and the have never broken a sharp tap. I've heard the "tink" of a marginally dull tap and was able to remove it before it broke, whew! Smaller taps can get pricey, but I figure my time is worth more than using a dull tap. Besides, I hate making the same part twice if I don't have to. ------- Date: Mon, 12 Dec 2005 01:13:42 -0000 From: "ptkeillor3" Subject: Re:Tapping methods Thanks everybody for some great ideas. I've got plenty of quill travel in my drill press (17" Jet). I'm going to buy or make some tap holders which allow gripping in the chuck while threading. The pin vise idea might be adapted as well. I'll also check the runout on my chuck (Jacobs 14N) before I start. Thanks again, Pete Keillor ------- From: "n2562001" Date: Thu Dec 1, 2005 11:34 am Subject: Re: Jerry K , how do accomplish pivoting with a Sherline ? [sherline group] Robert: The text and illustrations required to clearly explain making the smallest Taps and Dies is more than what is practical on this forum with my current Computer skills. Neil from Home Shop Machinist has been bugging me to write an article on this subject. I plan to do this as well as seminars on this subject sometime in the near future. The Short version for the smallest Taps and Dies is as follows. They are Machined from Brand Name A-2 drill rod that is packaged with hardening and tempering instructions for that product. For a Tap I generally start with 1/16" stock held in a WW collet in the Lathe. The outside diameter and shape is then machined in a normal manner. The thread is then single point cut on the lathe using a standard Sherline threading Attachment. In order to get up to 500 TPI a standard 127 tooth gear with a 25 tooth pinion gear is added between the (A) and (B) gear positions. For those who may ask CNC will not work well for this operation. First a .0005" deep thread is hard to control with the accuracy of a hobby system. Assuming that you could the relief ring left at the end of the thread when the tool stops moving will weaken a tap of this size so it will generally break at that point on first use. Once the thread has been cut the collet is transferred to the Mill/indexer. Two right angle cuts are then made 180 degree`s apart with a standard .010" end mill about .001" deep to generate a cutting edge and chip relief. The Taps are then Hardened and tempered using standard procedures from any Machinist hand book within manufactures recommendations. Once you have made a Tap you can then make a die using that tap. Dies need to be made adjustable for a proper nut to bolt fit. For adjustment and cutting/Chip clearence I make a single slit through the center of the Die similar to a commercial Die. For stability in this material the slitting saw needs to be about .008" making a slot far to wide for threads under .010". I then place .002" shim stock in the slot and press the Die stock over it in a Machine vise until I have a .002" slot. From that point it is drilled/threaded and hardened/Tempered. You then cross your fingers that they don`t break the first time you use them. Jerry Kieffer ------- From: "n2562001" Date: Thu Dec 1, 2005 3:22 pm Subject: Re: Jerry K , how do accomplish pivoting with a Sherline ? Gregg And Robert: All Micro Machining is done under a quality Loupe or Stereo Microscope. It is no more difficult to single point thread something like .012" stock if you make it look like its 1/2" diameter than if it actually is 1/2". Under quality Optic`s .0005" movement of the slides will feel like .250" on a large Lathe. I posted a Photo of a .012" X 250 TPI Tap being single point cut under a Stereo Microscope at 12 power. The actual view is of course much larger and clearer but this all we were able to get with the Camera that was used. The Photo is the last one in the section (No. 67) under the number 18. I will remove it in a day or so. Deflection is not a problem if metal is cut to size and removed in short sections allowing the full size stock to support each short section. One reason A-2 Drill rod is used is that it is more stable than some other metals, but at this size warping has not been a problem. Jerry Kieffer ------- NOTE TO FILE: A terrific article by Jerry Kieffer was published in the latest Jan-Feb 2006 Home Shop Machinist magazine on the subject of using magnifying devices in the workshop. Buy it. They will improve anybody's ability to really see what you are doing. (And if you think you don't need the devices yet, believe me, you will some day soon.) ------- Date: Tue, 3 Jan 2006 13:49:45 -0500 (GMT-05:00) From: Jim Ash Subject: Re: Procedure for using a tap on the lathe? [atlas_craftsman] "joegourlay" wrote: > I need to tap a 5/16" hole tonight. In my thinking, I get as far > as "chuck the tap into the tailstock". > How, then, is the tap fed into the work? Should I simply undo the > tailstock/way bolt and let the tap pull itself into the work? Don't chuck the tap in the tailstock. You need to be able to feel how the tap is cutting, and it might be difficult that way. Hopefully your tap (or your tap holder) has a center-drilled hole in the non-cutting end. Lock the spindle (engage your back gear without pulling the bull gear pin), mount a center in the tailstock, then sandwich the tap and holder between your work and the center. Lock the tailstock base to the ways and use the ram to put just a little pressure to get the tap started in the work. Turn the tap handle by hand, while advancing the ram just enough to keep the tap supported properly. You will be able to feel when the tap is loading up, which will vary depending on the tap and the material. When this happens, back off the ram and tap combination, then clear the chips from both the tap and the hole. Side note here - don't use compressed air to clear chips if this is a blind hole (You probably shouldn't be using comressed air at all). Air won't get to the bottom of the hole where you need it. When the need arises, I use small-diameter tubing, poke it all the way to the bottom of the hole and squirt cutting oil in. The oil bubbling out of the hole will carry chips out. After 4 or 5 turns, the tap will be self supporting and you could probably back off the tailstock, but I tend to continue using it as a safeguard against my un-even hand pressures on the tap handle. Jim Ash ------- Date: Wed, 4 Jan 2006 11:11:39 EST From: e.b.hunterx~xxieee.org Subject: Re:Cutting Metric Threads with an Atlas 10-D Lathe [atlas_craftsman] I had an interesting experience recently while trying to cut a 0.75 mm metric thread with a 10-D Atlas lathe. Some years ago I had downloaded an Atlas Threading Supplement that included instructions for cutting metric threads. So I assumed I could cut one if needed. But when I compared the illustrations in the book to the gear case of my 10 D, I realized the supplemant was written for the 10-F which has an expanded gear rack and a 32/16 first idler gear that is not found in the 10-D. I tried writing the gear reductions as a product of fractions and moved the numerators and denominators around to see if I could find a combination that would fit in the 10-D. This was complicated because I had to add an additional 2:1 reduction factor to compensate for the lack of the 32/16 idler found in the 10-F. But, I could not find a combination that would fit in my lathe without interference. In desperation I looked at cutting a 34 tpi thread, which repersents about a 0.3% pitch error from the desired 0.75 mm per revolution. This, too, required special "irrational" gearing, not shown in the lathe chart. However, by starting with the 34 tpi setup shown in the Threading Supplement, adding a 2:1 reduction, and manipulating the ratios expressed as the product of fractions, I came up with a combination that fit in the 10-D lathe. A 96 tooth gear had to go on the lower fork of the gear harp. As with cutting metric threads, the "irrational" 34 tpi thread required that the motor be reversed at the end of each cut to backup the carriage. This took a long time. However, I am pleased that the finished internal thread fit the intended mating part (coupling on a Russian klystron tube) just fine. The 0.3 % error did not have enough cumulative effect over about 1/4 inch of thread on the 20 mm diameter part to be a problem. I mention this experience because I have owned my lathe for about 47 years, have cut many threads with it, and did not expect to have a problem cutting any reasonable thread on a small part. However, I may have missed a more simplistic, commonly known solution. Have others had similar experiences with a 10-D? Bruce ------- Date: Fri, 6 Jan 2006 10:19:45 -0800 (PST) From: brogers1x~xxvcweb.org Subject: Source for Atlas Thread cutting tool [atlas_craftsman] I have an old Atlas Thread cutting tool. It is one of those where there is a circular tool steel wheel that is cut with a 60 degree bevel and is meant to be held by the old light-house tool holders. The cutting wheel has been sharpened (you just grind off the dull portion and expose the fresh portion) so many times that it is at the end of it's adjustment range. I see the complete tool on ebay, but all I need is the cutter wheel. The holder is fine. I have some regular 60 degree 1/4 x 1/4 cutters for cutting threads, but I wanted to try the old circular thread cutting wheel. Does anyone know where can I get the replacement cutter wheels? Bruce ------- Date: Sat, 7 Jan 2006 21:35:06 -0500 (EST) From: Steve Subject: re: Source for Atlas Thread cutting tool >Does anyone know where can I get the replacement cutter wheels? Bruce Bruce: As they said on Laugh-in: I have good news, und, I have bad news: The good news: The bit is available from MSC (part number 08640609 for what looks to be the same size as mine). The bad news: The price? $130. Yes, that's just for the bit. The bit looks slightly different (as does the holder), as the holder has an additional screw to prevent rotation, so I'm not sure it will fit the old lantern post toolholder anyway. The complete holder with the blade is only $22 more. Maybe picking one off ebay is looking better now. Or making one yourself. Looking at mine, it's just a disk with a 60 degree bevel edge, then a segment cut out. Steve ------- Date: Mon, 16 Jan 2006 16:54:28 -0000 From: "washcomp" Subject: Question on encasing steam engine cylinder in wood [LittleEngines group on Yahoo. No, this thread is about threading too, and you just might find the other info interesting. And now you know there are other groups out there with good ideas :-] I have a small steam engine that I would like to encase the cylinder (about 1 1/2" diameter) in wood slats. I would like to wrap two brass bands around them to hold the slats in place. Two questions: 1) What thickness brass should I use for the straps (and how do I neatly form the circular prifile)? 2) I'm going to have to drill and tap tiny screw holes in the body of the cast iron engine. Any advice on how to do this without leaving pieces of small taps behind would be appreciated. Regards, Jeff ------- Date: Mon, 16 Jan 2006 19:58:19 -0000 From: "colin heath" Subject: Re: Question on encasing steam engine cylinder in wood Hi Jeff: No Steam Engine expert but have done a fair bit of woodwork. The technique is called coopering. You put a small angle on the side of the pieces (lengthwise) so the pieces sit 'smoothish' around the radius. Then smooth out the sharp edges if required. a band could then be added. Perhaps a temp band would be required at one end while you smooth out the edges. Look it up on google under coopering and you will find all you need. Cheers Colin Heath ------- Date: Mon, 16 Jan 2006 21:27:03 -0600 From: gary Subject: Re: Question on encasing steam engine cylinder in wood A lesson learned on tapping small holes in valuable parts. A long time ago I was drilling and tapping a lot of rifle receivers some of which in finished guns were quite expensive. I had invested in a drilling jig to perfectly position drill and tapping bushings on the top of the receiver. For tooling I had purchased premium HSS #31 drills and HSS 6-48 taps since some receivers are quite tough. A local gunsmith who made his living by Repairing guns other people had Fixed, looked over my shoulder as I was tapping a receiver and asked how many of taps I had broken. I proudly told that so far I hadn't broken any. His remarked that this only meant that I hadn't tapped very many holes and how was I going to get the tap out after I broke it. I went into my tap extractor - tap burner spiel and he looked at me, laughed and muttered an expletive concerning the relative location of my head to other parts of my lower anatomy. He told me to put the HSS taps away and get the cheapest high carbon taps I could find then to use them once or twice and throw them away. After I got the carbon taps he broke one off in a hole intentionally and then using a small punch proceeded to break the broken tap into a bunch of small pieces. The pieces all fell out and left a clean hole. We then tried this with the HSS tap in a piece of scrap. The HSS tap was harder to break but when we tried to get it out, it proved impossible. I couldn't turn it out with pins and the small stub sticking out of the hole was to small to grasp. When we tried to break it with a punch it just turned into a mangled mass of HSS and to the best of my knowledge it is still located inside that piece of scrap. I can't tell you how to avoid breaking taps because I have never learned how not to do it but I can tell you that cheap high carbon taps are a lot easier to get out after they break. BTW - The high point of this experience was the look on a well known customers face when I told him that I had broken a tap off in his rifle and couldn't get it out. I explained that it was okay however since the tap had broken off quite high. I then gave him his rifle with a broken tap projecting through the scope base and a hex nut screwed on it to hold everything in place. Initially he didn't see the humor in this. gary ------- Date: Tue, 17 Jan 2006 08:11:59 -0500 From: "Jeff Goldberg" Subject: RE: Question on encasing steam engine cylinder in wood Thanks Gary. I was wondering if the fact that the material to be tapped was cast iron made things different. I seem to remember that you are not supposed to use lubricating oil, but I forget why not :-( Jeff ------- Date: Tue, 17 Jan 2006 08:39:06 -0500 From: "Andy Wander" Subject: RE: Question on encasing steam engine cylinder in wood Cast iron sort of "crumbles" into a very abrasive gritty powder. Adding lubrication makes a very effective lapping paste. The usual recom- mendation is to machine cast iron without any oil. This includes tapping. Andy Wander PS I bet those rifle receivers weren't cast iron! ------- Date: Tue, 17 Jan 2006 08:43:57 -0800 From: "Carl Carlsen" Subject: RE: Question on encasing steam engine cylinder in wood From: Jeff Goldberg >Any advice on what I should do about tapping tiny screws in cast iron >(other than pray)? The holes would be on the main casting of the engine >and the thing is very awkward to work on. Jeff, I assume you made a 'set-up' to bore the holes? While in the same setup, take out the bit and thread it, using your "spindle" (chuck or whatever) as your loose guide for the tap. The Mery engine has 4 holes (#2 tap) in the outside of the cylinder to hold the nameplates ... the holes are at an angle. While on the table in their original 'boring setup', once I had a hole bored, I tapped it. Awkward yes...problem NO. Carl ------- NOTE TO FILE: Naturally if you are reading this file with the intent of learning about lathe tools and their cutters, you will also want to read the "Cutters, Collets and Arbors" file here. It will also be useful to learn more about single point cutters (for use on the lathe) in the "Shaper Bits and Toolholders" file where single point cutters are also used. In many instances the same cutter or holder can be used on both lathe AND shaper. ------- Date: Tue, 04 Apr 2006 02:56:05 -0000 From: "Jim B." Subject: Re: Cutting metric threads [beginnerswkshp] Hi all :) I have one really nagging question on metric threads that I can't seem to find an answer to anywhere; When cutting metric threads, is it necessary to use the dial indicator to judge when to re-engage the split-nut (ie: on the second, third, etc. passes), or can it be simply re-engaged once the carriage is returned to beyond the starting end, with the new depth-of-cut setting for subsequent passes? With standard threads it is necessary to do so, but just tinkering with it, I was able to make a second and third pass in exactly the right spot, without bothering with the dial indicator. Was that just blind luck? The thread size I happened to be messing with at the time was 1.25mm, with the appropriate change gears in place. My lathe is a "Craftex" 10x18, standard & metric thread cutting (Busy Bee Tools in Canada sells them.) Jim ------- Date: Tue, 4 Apr 2006 07:46:48 -0500 From: "John Archibald" Subject: Re: Re: Cutting metric threads Jim: Just never disengage the carriage from the leadscrew and you'll be fine. Make all "adjustments" with the compound slide. Archibald ------- Date: Tue, 04 Apr 2006 12:50:18 +0000 From: j.w.earlyx~xxatt.net Subject: Re: Re: Cutting metric threads Jim: After doing the heart wrenching procedures with the thread dial for over 30 years and suffering indigestion from the nervous reaction to the stress involved I have removed the thread indicator dial from all of my lathes and placed them in a dark drawer of my least used tool cabinet. Thanks to a suggestion from a friend on one of the groups a couple of years ago about how much easier he found cutting threads the metric way without the thread dial I tried it myself. Instant convert to the method and now my thread cutting is stress free and comfortable. I actually enjoy cutting threads on the lathe now, it is fun. JWE Long Beach, CA ------- Date: Tue, 4 Apr 2006 16:51:49 +0100 From: "Ellis Cory" Subject: Re: Re: Cutting metric threads Jim wrote: > I'd be concerned about how fast the lathe would stop if the threads > were to come up tight to a shoulder, ie; if it would stop in time... Use a handle in the outboard end of the spindle and hand crank it. If you wish to, after clearing the cross slide, you can return it carefully under power. HTH. Ellis ------- Date: Tue, 04 Apr 2006 16:13:44 +0000 From: physistx~xxcomcast.net Subject: Re: Re: Cutting metric threads There is available and I have made, a lever, used to hand turn the spindle. This allows you to stop the thread early and finish the cut by hand. The ones I have seen use an expanding mandrel in the spindle bore. I don't like them because then you cant have stock in the bore. The one I made slips onto the motor drive shafting. This also provides more leverage. Jim B (Physist) ------- Date: Fri, 07 Apr 2006 17:31:07 -0000 From: "JohnW" Subject: rear mounted upside down tool [beginnerswkshp] [actually a follow on to the "Cutting metric threads" conversation] A front mounted tool will spring down and usually in (depends on toolpost geometry and diameter of workpiece. Springing in tends to lead to chatter which sometimes is worse on light cuts versus heavy cuts. A rear mounted upside down tool springs up and out and doesn't tend to chatter. Even so I still cut threads from the front except for female threads. For those I mount the tool upside down and cut on the back side. This allows me to leave the compound at the same 29+ degree setting as for male threads. Someone on the Southbend10k groups suggested this method. JohnW ------- Date: Sat, 8 Apr 2006 11:48:20 -0400 From: "Cliff Ward" Subject: RE: rear mounted upside down tool John: Your posting came at a particularly helpful time for me. I'm still very much a novice with my lathe, and am learning every day. I needed a female 1/2-24 UNS thread in an iron casting, and had been concerned about ruining the part since I only have a 7/12 Chinese lathe that has marginal stiffness....so I decided to try your upside down, back side tool mounting for the cutting bit, and found it really worked great ...no chatter and controllable cutting. I'll use this technique from now on for cutting female threads. Thanks for the tip...I was afraid to tackle this one for some time, and am convinced the back side technique was key to my success. Regards, Cliff ------- From: "John W." hazmat_techx~xxmac.com Date: Tue Apr 11, 2006 10:01am(PDT) Subject: Re: Grizzly Threading Tool Bits [atlas_craftsman] >>Who would ever want 55-degree threading tools? Am I missing something? True Whitworth threads have a rounded crest and valley as well as the 55 degree pitch angle (extra surface area to provide a tighter lock-up and less chance to back out). In Mauser rifles, the thread pitch is indeed 55 degrees, but the do not carry the whitworth rounds at valley and crest. Set the tool to cut on the front (leading edge) side only with this surface set to the 60 degree pitch. This does 2 things, it provides a true single point thread cutting tool, and it removes any irregularities on the rear thread face angle that destroys an accurate thread fit (or in some cases burnishes the thread face). I grind my 60 degree tools to 59 (or thereabout) degrees to accomplish this, and the same should be true for inserts cut to 55 degrees (on my single point tools for mausers I grind sub-55 degree angles to insure thread quality). I set my compound at the appropriate angle to cut the desired thread pitch angle and feed only from the compound. Now if you REALLY want to have fun, custom grind your tool steel for the square and/or ACME threads found in many antique black powder rifle (and some lever gun) actions and set for an accurate feed to time a hex barrel with maximum thread contact... John ------- From: "ekzacto" thompsonjcx~xxsbcglobal.net Date: Wed Apr 12, 2006 10:03pm(PDT) Subject: Grizzly Threading Toolbits (Followup) Thanks to everybody who educated me about Whitworth threads. I still think that Grizzly's catalog should have said that the pre-ground threading tools I ordered were not standard 60 degrees. I don't do gunsmithing, optics, camera work or anything else where I would need Whitworth threads. The majority of my threading work is cutting external threads to mate with store-bought NC and NF nuts and other 60-degree internal-threaded hardware. I ended up sending the set of toolbits back to Grizzly for credit, eating the two-way cost of shipping. I talked to Grizzly's technical department about what I considered misleading in their catalog not saying the toolbits were 55-degrees. I was told that before ordering, I should always call to ask about detailed specs not listed in their catalog, and never assume that an item will comply with the usual American standards without confirming. Thanks again to a great group, Chuck ------- From: "joe amodeo" Date: Sun Apr 23, 2006 3:30 pm Subject: fine threads vs coarse threads [sherline] After years of pondering I still can't decide which thread pitch has more holding strength, fine or coarse? I believe fine pitch is less likely to loosen and back out. Which would strip easier? I need to attach a piece of aluminum to a piece of .125 ABS. Unfortunately the threads are in the plastic. Joe ------- From: "Jerry G" Date: Sun Apr 23, 2006 Subject: Re: [sherline] fine threads vs coarse threads We can kick this around for a while. You can look up the stripping strength and tensile strength of materials, and different threads. If you are concerned with backing out, you can use Locktite... Or a Nylock screw... or pin it... so many ways to go. But my suggestion is: Do you have room to put a steel insert or Helicoils in the ABS? Is the .125 in inches? Is it round? Be specific, man..... Jerry G (Glickstein) P.S. Willing to help, but give me a clue... :) ------- From: Date: Sun Apr 23, 2006 5:06 pm Subject: Re: [sherline] fine threads vs coarse threads Jerry: To be more specific, the threads are two feet down from the end of a 4 foot section of 2 inch ABS plumbing type pipe with a .170 wall thickness. Yes, that would be in inches. I don't go for that metric stuff, hard or soft. I would like to drill an oversize hole and insert a flanged insert from the inside of the pipe but I can't get my fat fingers to reach that far in. Helicoils are a good idea, especially if I had to screw the bolt in and out more than once. I wonder, would the Helicoil threads hold any better than the bolt's own threads? Its not a critical application. Just to hold the ABS vacuum tube originating from a Torit vacuum machine model # 66. It will be vacuuming tungsten dust from a 2 inch diamond grinding wheel spinning at 10,000 rpm, all of which is part of a 4 axis C.N.C grinding machine I built in my spare time (nights and weekends) over the past three years. Thanks for your input. Joe ------- From: Keith Green Date: Sun Apr 23, 2006 Subject: Re: [sherline] fine threads vs coarse threads I think it depends on the materials you're joining as well as how long and what material the screw is made of. Also, the tolerances to which the threads are cut. All that aside, I read an article in a woodworking magazine a couple years ago where they tested this question. To everyone's surprise, the fine machine threads held better in wood (under most circumstances) than anything else tested. They figured it came down to amount of surface area in the thread interface or something like that. I would probably go with the fine threads in plastic. Keith ------- From: "dap1823" Date: Sun Apr 23, 2006 5:38 pm Subject: Re: fine threads vs coarse threads > Keith, I'm really surprised. Fine threads in wood? That's really > counterintuitive. Joe When you make miniature, like myself the wood threading comes in handy. Sometimes it tears out in different wood, but CA glue solves the problem. CA and then thread ... you can make some very small threads. ------- From: "Jerry G" Date: Mon Apr 24, 2006 5:57 am Subject: Emailing: helicoil Attention Joe!, Look up all you need to know about Helicoils. I sent it to the Forum in case it will help others. While I was working before I retired all the companies making high tech stuff used helicoils as part of the government military specs. I still have a gang of insertion tools and assorted helicoils in my toolbox. Shortcut to: http://www.helicoil.com/products/helicoil.html Regards, Jerry G (Glickstein) ------- Date: Sun, 30 Apr 2006 09:14:39 -0000 From: "Ernie" Subject: Fine taps [LittleEngines] I need 3/16-40 tap and die. Anyone know where I can get? Or do I need to cut my own threads? Thanks Ernie South Florida ------- Date: Sun, 30 Apr 2006 13:19:48 +0200 From: "Frank Hasieber" Subject: RE: Fine taps 3/16 x 40 is a Model Engineer thread size, they are available from Chronos in the UK, I have bought from them in the past with very good service, and the only problem might be that they have a minimum order of 15 pounds, you could however get a few other sizes to bring the order up to that amount. http://www.chronos.ltd.uk/acatalog/ Do a search for 3/16 x 40 Model Engineer Taps. They are however only available in carbon, not HSS. The taps are Ł2.21 and the dies Ł4.89 plus shipping. There should however be suppliers in the USA. Another one you could try is Tracy Tools UK http://www.tracytools.com/products.htm Frank ------- Date: Sun, 30 Apr 2006 09:05:51 -0400 From: "Aaron Pasteris" Subject: Re: Fine taps Try PM Research for the tap in the US. http://www.pmresearchinc.com/store/customer/home.php?cat=68 Aaron ------- Date: Sun, 30 Apr 2006 15:18:53 +0200 From: "Johan" Subject: Re: Fine taps Ernie: Try AJ Reeves in Birmingham. http://www.ajreeves.com Regards, Johan Pretorius South Africa ------- Date: Sun, 30 Apr 2006 12:10:38 -0400 From: "Jim Dunmyer" Subject: Re: Fine taps Ernie: When we started building model engines, we needed several taps that seemed like "weird threads" to me. Little did I know! All of 'em were available from our local supplier, T&S Tool & Supply, most were in stock. Taps & dies included 1/2-32, 5/16-32, 3/8-40, 1/4-40, 1/16-27 Npt, in addition to the old standards of 0-80, 2-56, 3-48, etc. T&S is at 1-800-525-8665 or http://www.tstool.com Of course, we've also had good luck at Enco, http://www.use-enco.com Usual disclaimers apply. Jim lower SE Michigan, USA http://www.oldengine.org/members/jdunmyer ------- Date: Sun, 30 Apr 2006 14:35:07 -0000 From: "gailnmrc" Subject: Re: Fine taps In the US #10-40 can often be substituted as they are only 0.0025 larger on the diameter. That size is available from stock as a "standard" special at many of the industrial distributors such as MSC. Gail in NM, USA ------- NOTE TO FILE: Those folks who like antique hand tools face an adventure in threading rarely encountered in the typical workshop. Stanley was particularly innovative in using/creating some extremely odd threaded holes at their factory. Not a problem if the tool has all its screws, but Murphy says that rarely happens except with common threads. Some good folks out there carry custom taps and dies in some oddball threads. Metalworkers have the added advantage of being able to make many oddball threads for custom taps and dies. These don't have to be pretty -- they just have to work a few times to solve today's problem. ------- Date: Sun, 11 Jun 2006 15:12:42 -0400 From: "Gary Katsanis" Subject: Re: [OldTools] Stanley tap & Dies [oldtools group] "Thomas W. Hoyt" wrote: --snip, snip-- > Real question: IF I wanted to get taps & dies to clean/repair threads > on some old planes - would a rather standard set of taps & dies work > for most of those? I understand that St James Bay has custom taps and dies for the Stanley bench plane threading. Gary K Close to Buffalo NY PS - no affiliation, YMMV - GK Forwarded from Mike Taylor: Bob Howard of St. James Bay Tool Co. has ordered the taps and dies. Please call him to place your order using a credit card or send payment by check or money order. 12-20 die - $22.00 12-20 tap (plug tap) - $15.00 a set of both the above for $35. The above prices include shipping charges to USA destinations. His address is: St. James Bay Tool Co. 122 East Main St. Mesa, AZ 85201 (800) 574-2589 ------- NOTE TO FILE: The St. James Bay Tool Co. is better known for a high quality selection of woodworking tools' parts and castings, including kits for beautiful projects that will be a joy for metalworkers. See: http://www.stjamesbaytoolco.com/ ------- Tailstock die holder [taigtools] Posted by: "Collins, Graham" collingx~xxnavcanada.ca Date: Thu Jun 15, 2006 5:04 am (PDT) I have (up til now) only used a regular die stock to hold a die while threading on my lathe. As a quickie weekend project for my grandson and I, I was thinking of making up a tailstock die holder. First step was just to see what was available and any other possible variations I might find on the internet. All variations are of the form where the die is in a holder, where that holder is then turned by hand presumably while the part to be threaded is held stationary in the lathe's chuck. That is all fine and dandy and is in line with my earlier machine shop training. However, why not hold the die in a holder that is stationary on the tailstock and turn the part by turning (by hand) the lathe's chuck or in the case of a Sherline or Taig lathe, the headstock spindle either from the driving pulley on the motor or the driven pulley on the spindle? Certainly there would be limitations on the size of the part being threaded; that is, the larger the part, the more force needed to turn. But for small parts this should certainly work well. So, what do you think? Yes? NO? Why? Cheers Graham in Embrun near Ottawa Canada. ------- Re: Tailstock die holder Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Thu Jun 15, 2006 12:26 pm (PDT) Graham: For Sherline/Taig size machines I have never seen the logic of Tailstock Die holders. Because of the sizes threaded in these machines, one can simply put any size die in the Three jaw chuck and hold the work piece in the tailstock drill chuck. This will allow any length thread -- even threaded rod not possible with a Tailstock die holder. Not to mention that it is much faster with no needed accessories. With the DC motor on a Sherline, threads up to 10-32 can be cut under power at about 20-30 RPM. I have added a reverse switch to the system that produces instant reverse under load without stopping. When I reach the correct or marked depth, I flip the switch and get instant reverse as well as having the work piece backed out of the Die under power. For this procedure, the Tailstock is left loose so it will freely slide on the lathe bed. I am sure this can be classified as abuse of the motor system, but I have had no problems doing this on a semi regular basis for the last ten years. I have never tried this with a Treadmill motor as used on many Taig Lathes so I can`t comment on the durability of that system. Because of the low cost of the motors I see no reason not to try it. Of course threads can also be cut by turning either chuck while holding the other. Jerry Kieffer ------- Re: Tailstock die holder Posted by: "benedict-listx~xxhawaii.rr.com" Date: Thu Jun 15, 2006 12:52 pm (PDT) Jerry, I have to laugh at myself...until I read this, it never occurred to me to arrange things that way. Now that I've read it it makes perfect sense. Sheesh! I'm slapping my forehead a bit here since I've used this trick on the mills at work for power tapping, and was recently eyeballing our one non- reversing mill and grumbling that it should have a reversible spindle. I never made the connection to my own tools. Time to add reverse switches to my lathe and mill, and time to look at my drill press in a whole new way. Thanks for the post! Tom ------- Re: Tailstock die holder Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Thu Jun 15, 2006 1:58 pm (PDT) Jerry - Nice technique! I regularly tap holes under power on my Taig (tap in the tailstock chuck, and as you say, leave the tailstock free to move) and use the reversing switch to back the tap out again, but it had never occurred to me to hold dies that way around. That has to be one for the next revision of the book ;-) Regards, Tony ------- Re: Thread Cutting information [LittleEngines] Posted by: "Ellis Cory" ellis103x~xxtiscali.co.uk Date: Wed Jul 19, 2006 2:16 pm (PDT) Russell wrote > i am looking for charts (or formula) to determine the size of stock > i should use to cut external threads, specifically BA sizes. Take a look here http://www.bhi.co.uk/hints/bathrd.htm Ellis ------- Re: Thread Cutting information Posted by: "Carl Carlsen" kd7bfnx~xxearthlink.net Date: Sat Jul 22, 2006 10:26 pm (PDT) Russel: Here are a few references. Not all have "charts" but provide means of computing the Major and Minor diameters. There are "charts" which provide this information and as has been suggested, The Machinery Handbook should have good information on this. http://www.mohawk-mfg.com/technical_information.htm http://www.zerofast.com/thread.htm http://mdmetric.com/tech/tic1e.htm http://www.sherline.com/3100inst.htm Carl ------- More tap lore [taigtools] Posted by: "Richard" phrhx~xxworldnet.att.net Date: Wed Aug 2, 2006 4:38 am (PDT) Many grind all but one thread off a row on a tap and use it as a thread- cutting tool. Mert Baker (you all know him) suggested that grinding the threads need not be done, it works as is. Why not? For a given pitch we can thread internally any size hole (camera parts etc) with one tap. I have tried it. Richard ------- Re: More tap lore Posted by: "javaguy11111" javaguy11111x~xxyahoo.com Date: Wed Aug 2, 2006 7:57 am (PDT) Is there a particular post that describes this. I have been wanting to give threadmilling a try, but I did not want to grind up one of my good taps to try it. ------- Re: More tap lore Posted by: "Jim" samadams4qx~xxyahoo.com Date: Wed Aug 2, 2006 9:20 am (PDT) I've used a tap like this before too, and it does work great as an internal threading tool. I suggest grinding all but one thread when cutting larger diameter internal threads because the thread angle between the tap's cutting edges would be slightly higher. Since you have 3 or 4 flutes to play with, you can try several different grinds on the same tap. I've also used a tap as a crude gear hob. If you grind all the flutes but one, you can use it with an index plate or rotary table. If you leave the tap as is you can somewhat successfully hob a worm gear if you mount the gear blank in a free spinning fixture. Jose Rodriguez has a pretty good video on gear making that shows this method. However, gears usually have a 14.5 or 20 degree pressure angle and a tap is 30 degrees. Jim ------- Re: More tap lore Posted by: "benedict-listx~xxhawaii.rr.com" Date: Wed Aug 2, 2006 12:31 pm (PDT) Thanks for sending out the tap lore! I must admit, my eyebrows went up when I read your previous post about using one as a boring bar. [NOTE TO FILE: THAT JULY 2006 CONVERSATION IS IN THIS SITE'S BORING FILE.] And yeah, after thinking about it for a while it made perfect sense. I hadn't considered this neAt bit of advice, but it makes perfect sense. I've also heard of people grinding off all but one fully-formed tooth, and using the ground-down tap as a single point thread mill on a CNC machine. Too fun! I'm writing these down. Thanks! Tom ------- Re: More tap lore Posted by: "benedict-listx~xxhawaii.rr.com" Date: Wed Aug 2, 2006 4:11 pm (PDT) On O2 Aug 2006, Jim wrote: > I've also used a tap as a crude gear hob. ...However, gears > usually have a 14.5 or 20 degree pressure angle and a tap is 30 degrees. I tried it recently, and it worked out great. Here's the full story: There's a robot club forming in town, and I'm getting into robotics (among other things). One kind of robot I'm not ready to jump into yet, but that has a lot of appeal because of the size factor is nano sumo robots. They're 25mm on a side and have to weigh practically nothing. There's an Atmel AVR processor board available that's 0.9" square, so yeah, you really can make one of these beasties and not lose processing power along the way. (Do a Google search on "megabitty". Fun stuff.) Anyhoo, one of the big gotchas is propulsion. Pager motors are small enough to fit inside that envelope, but they still need to be geared down. There are lots of nice products along those lines (believe it or not, pager motors with tiny planetary gearboxes attached), but what's the fun of a shop if you don't get in over your head from time to time? So the question came up: Can I stick something like a length of #2-56 threaded rod onto a pager motor shaft and have it act like a worm gear? To test the thread hobbing thing I turned down a length of 1/4" diameter 6061, chucked it in a Foredom handpiece I had mounted on the milling attachment on my lathe, and let the handpiece free-wheel. I then chucked up a #2-56 tap in the lathe headstock and indicated it in for as close to zero run-out as I could get. A slow spindle speed and plenty of cutting oil produced a really nice little gear, albeit with a tooth profile that would only let it engage a threaded rod. But since that's what I was sticking on the motor as my worm, I was pleased as punch. I can't say that's the ideal way to cut gears, but at that scale I'm willing to take the hit in tooth form and efficiency of the gear train in order to make something that'd be tough to reproduce with off-the-shelf parts. Tom ------- Re: More tap lore Posted by: "Richard" phrhx~xxworldnet.att.net Date: Thu Aug 3, 2006 2:19 am (PDT) Tom there is a little more interesting info regarding the use of taps for other jobs, shown in the links section under Richard's shop. Take a look at a cheap dividing head. Richard [LATER MESSAGE] Using the same link and looking at Powerfeed for the Gingery miller shows some more on strange tap usage. ------- A 30 second Metric Conversion for the Atlas 10" lathe [atlas_craftsman] Posted by: "cwlathes" carvelwx~xxabsamail.co.za Date: Sun Oct 15, 2006 12:43 pm (PDT) A 30 second "Metric Conversion" for the Atlas 10" lathe fitted with the Quick Change screw cutting gearbox. I don't know whether this simple modification has been published before, if so I am not aware of it, and it is therefore shared/repeated here for others who may be interested in this approach. At Jon's suggestion I will see if I can load a PDF version of it on the Files section for easy reference. One of my main interests is the restoration of classic cars and motor- bikes, but as fate would have it, of both European and British origin - which involves fabricating small parts with both Metric and Imperial threads. Although I also have a largish lathe with a full Metric and Imperial gearbox, it is a bit clumsy for smaller threads, and I had often looked longingly at the gearbox on the Atlas and wished it read "mm" instead of "tpi"! This prompted me to start reflecting on whether some form of easily implementable, and reversible, approach was not possible which would allow the cutting of the most often used smaller Metric pitches of 1mm, 1.25mm, and 1.5mm. The problem with most Imperial gearboxes is that the tpi intervals don't readily equate to any Metric pitch intervals - with one exception. While most Imperial gearboxes (Myford, South Bend, Smart and Brown etc) would typically include a range of say 16 to 28 tpi, Atlas in its wisdom extended this similar range to 30 tpi. In staring at these figures and playing with the ratios, I realized that 30 tpi / 24 tpi / 20 tpi represented the same ratio intervals as 1mm / 1.25mm / 1.5mm, and so the seed was born. If one could easily convert 30 tpi to 1 mm pitch, then the 24 tpi and 20 tpi positions would correspond to 1.25m and 1.5mm respectively, giving the three most needed ranges (in my case). 30 tpi = 25.4/30 = 0.8467 mm, but how to get this to 1mm? Atlas to the rescue again courtesy of their 52 and 44 tooth gears with 0.8467 x 52/44 = 1.0006 mm - what a pleasure. The next obvious question was how to introduce this into the gear chain in the least painful way. Examination of the standard set up for driving the Quick Change box from the spindle reveals that the tumbler gears include a 32/16 shielded gear which in turn drives a 40 tooth sliding gear, which in turn drives the box through a back to back pair of 48 tooth idlers. The 52/44 combination fits quite neatly in place of the 48/48 idler, and herein lies the trick. With the 40 tooth sliding gear engaging the 52 tooth gear to the box, the 52 tooth gear is acting as an idler, (with the 44 tooth gear as its spacer), and the gearbox operates in its normal `Imperial Mode' with the exception of the coarsest (seldom used) range. However with the 40 tooth sliding gear in the other position, it engages the 44 tooth gear of the 52/44 combination and introduces the 52/44 ratio into the chain driving the box. The 30/24/20 positions, or 60/48/40 positions, become the desired 1mm/1.25 mm/1.5 mm pitches, depending on whether the 52 tooth gear of the 52/44 pair has been placed closest to, or away from, the headstock. In my case, I placed it away from the headstock to maintain the bulk of the tpi and feed settings as per the chart on the gearbox, so as not to have to remember to double everything as would be the case if the sliding gear was driving off the 32 tooth part of the shielded tumbler gear. All that is required to switch between the normal "Imperial Mode" and the "Metric Mode" is the few seconds it takes to loosen the yoke, and to move the sliding gear in or out. Have fun, and hopes this adds to the pleasure and convenience of your Atlas lathe if you have the same need. Carvel (Johannesburg, South Africa) ------- NOTE TO FILE: The following is one reply to a question as to whether there is any need to ream a hole before tapping it. [Definitely not needed.] There are some other good threading tips here. ------- about drilling, tapping and reaming [sherline] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Thu Nov 23, 2006 8:17 pm ((PST)) Hello Group, For much good info about drills, see mcmastercarr.com page 2314. For drilling holes to be tapped I suggest split point, stubby, TiN coated drills. With these you generally don't need to center drill. (Exceptions would include very hard materials and/or curved surfaces e.g. drilling into the side of a hard steel shaft.) Years ago I bought 2 each for tap and clearance holes in sizes I use: 2-56, 4-40, 8-32, 10-32, 1/4-28. Keep these, sorted along with their taps, in a compartmented platic box. Very handy. For info about taps, see mcmastercarr.com page 2270. Standard HSS hand taps will do fine most all the time. If you don't mind spending a bit more; consider spiral point (AKA gun taps) for through hole and spiral flute taps for blind holes. When starting a tap, it's important to use some kind of guide for the first few turns. A tap that's started straight will stay straight; one that starts bad will get worse. After that it's most important to be able to feel the torque and to reverse the tap every few turns to break the chips. And always use a cutting fluid. For info about reamers, see mcmastercarr.com page 2362. About the only reason to ream a hole is if you need to fit a shaft, bushing or pin. "Fits and Finishes" is a huge topic. General advice: You'll probably only ever need a couple of different sizes. For pins, .001 under for a press fit, .001 over for a locating fit. In my box I think I've got size, over and under for 1/8, 3/16, and 1/4; plus on size 3/8 and 1/2. Very much doubt I'll ever need anything else. I have no affilation with McMaster-Carr except many years as highly satisfied customer. They are fast. In Southern Maryland, if I order on-line before 10am, I've usually got it the following afternoon. Prices are good; but for small quantities of materials you may do better from vendors that cater to hobbiests. regards, DC ------- Re: ACME thread query [atlas_craftsman] Posted by: "Archie" jeep_32x~xxhughes.net Date: Mon Feb 19, 2007 11:04 pm ((PST)) Kirk Hillman wrote: > I was reading recently about producing large ACME threads for heavy > machines. How would one go about, or even plan to cut large threads like > this on a lathe like ours... or any other? The specifics are that I am > interested in figuring out a way to cut threads of between 2.5 and 3.5 > TPI (based on a single start). The shaft diameter would be in the > 1.25" to 1.5" Buy the acme threaded rod and and buy a acme tap and concentrate on making your project. The tap will come in handy in the future and you still have a lot of machining to get it from that point to finished product. Happy Hunting Archie Oh and there is a wealth of information in Machinerys Handbook, as well as on the net -- search cutting acme threads. One site to look at: http://www.armurerieduroi.com/pages/lathe/lathe_acme.html ------- Re: ACME thread query Posted by: "William Abernathy" williamx~xxinch.com Date: Mon Feb 19, 2007 11:22 pm ((PST)) Using an Atlas, this is in all likelihood going to prove a lesson in futility. For starters, the basic Atlas quick-change gear train only goes up to 4 TPI, so you will be messing around with change gears to get ratios as steep as 3.5 or 2.5 TPI. Second, though the machine *can* push the cutter ahead a quarter inch or more every turn, that's not to say it does it gracefully, or even especially well. Third, any really large Acme thread will require that you move a *lot* of metal to get a proper thread form. To get that form, you will need to grind or purchase one fat tool, which you will likely need to slant into the pitch of the thread, and odds are that as you get closer to your final dimension, you will start to get horrific chatter. Finally, you should bear in mind that if you're turning a long 1 1/2" rod on the lathe, you're turning something that's going to be a significant fraction of the mass of the lathe's bed. If there is an argument between your lathe and the part, you want the lathe to win without going to the score cards: it's best for the lathe to be lots bigger than the work. I'm not saying it can't be done, because I'm sure there are a few old geezers on this list with enough base cunning and lathe-fu to pull off a stunt like this; however, as a beginner project, you might want to learn how to cut conventional SAE threads in "mere mortal" sizes before you tackle Mission Impossible. If you want to try a big metal project, your best bet is to use the big metal lathe you are lucky enough to have access to. William A. ------- Re: ACME thread query Posted by: "Glenn N" sleykinx~xxcharter.net Date: Tue Feb 20, 2007 12:13 am ((PST)) There was recently a thread on this on the Quorn users group. The fellow used a hand crank on the feed screw and change gears along with the QC to get to 2 TPI. He used a toolpost grinder and a HSS cutting tool to actually cut the threads. I don't know if they were ACME form or just square though. ------- Re: ACME thread query Posted by: "jerdal" jerdalx~xxbrick.net Date: Tue Feb 20, 2007 8:59 pm ((PST)) The big problem is how fast the lead screw spins for this thread pitch. So, as mentioned, reverse it..... drive the lead screw, and let IT drive the spindle. The hand crank sounds like a lot of work..... typical of UK model engineering types, but using a small motor to drive it sounds much more reasonable. Make up a pulley that will go where the extra gear on the leadscrew would go. Usually there is space for two; dunno about Atlas. In any case, belted to that, the motor will run the lathe and you should be able to cut OK. The speed reduction will allow lots of torque, so go easy and don't have a dig-in. JT ------- Re: ACME thread query Posted by: "rwp399" rwp399x~xxyahoo.com Date: Wed Feb 21, 2007 5:35 am ((PST)) I saved the following web site from an earlier discussion of acme threads. It may be of some help in design. http://icrank.com/cgi-bin/pageman/pageout.cgi?path=/data/ac me/acme.htm&t=2. Bob ------- Re: ACME thread query Posted by: "jmartin957x~xxaol.com" Date: Wed Feb 21, 2007 6:19 am ((PST)) jerdalx~xxbrick.net writes: > So, as mentioned, reverse it..... drive the lead screw, and let IT > drive thespindle. I agree, in theory. In practice, it might be a bit different. The problem is that you'll be driving the spindle through the spindle gear, which won't stand up to a lot of torque. You could certainly cut a thread of this pitch this way. A 10 start 1/2" pitch thread would be easy, because each threading cut would remove only as much metal as a 20 tpi single start thread would. But when you are looking at a 2 or 2.5 tpi Acme thread, you are taking off a huge amount of material. The only way a small lathe can do that is by driving the bull gear through the back gears, which driving from the leadscrew would not do. You could, I suppose, use a toolpost grinder to grind the thread, and drive the spindle from the leadscrew. John Martin ------- Re: ACME thread query Posted by: "n8as1x~xxaol.com" Date: Wed Feb 21, 2007 8:37 pm ((PST)) jmartin957x~xxaol.com writes: > But when you are looking at a 2 or 2.5 tpi Acme thread, you are taking off a huge amount of material. The only way a small lathe can do that is by driving the bull gear through the back < if u are going to try this , i wud set the compound at 90 deg to the x feed, then use a 50 to 75 % wide bit & cut to full depth ...then " stone up " bit & use compound to trim rt/left few thou at a time till nut fits.......have cut several square & acme thrds this english/canadian way & find it easier on the eyes & nerves ..... best wishs docn8as ------- Re: ACME thread query Posted by: "jerdal" jerdalx~xxbrick.net Date: Wed Feb 21, 2007 6:39 pm ((PST)) John: WEll, that works both ways. The lead screw cannot be DRIVEN well because of the huge speed increase down the gear train to the leadscrew, PLUS the torque required to move it along at a rapid clip while cutting a coarse thread.... A lot of force, something lightweight will break. At least driving in reverse, you have control over the cut, and are operating a speed reduction. So taking THAT side as the driving side is a sensible way of doing something that shouldn't be done... A real lathe has a large diameter 2tpi LS and would eat that task for a snack. JT ------- Re: ACME thread query Posted by: "Kirk Hillman" hillman88x~xxtelus.net Date: Wed Feb 21, 2007 8:11 pm ((PST)) Thanks ALL for the terrific input. More than likely this little puzzle will be attempted on the larger lathe. It's still a little awkward figuring out the best way to cut such a coarse pitch. I've not seen any lathes with specs saying they'll generically cut such threads. It could be a case of not understanding what needs to be done though, on my part. On the large lathe I'm not sure how to drive the leadscrew either, if that was the best option. It's encased on either end IIRC. I suppose the first thing to do is get a closer look at it to determine available feed rates per rotation, etc. Thanks again, Kirk ------- Strength of a tapped #2-56 thread? [Min_Int_Comb_Eng] Posted by: "gehaddad" gehaddadx~xxhotmail.com Date: Wed Sep 5, 2007 10:30 am ((PDT)) How deep should a tapped #2-56 thread be for maximal bolt strength. I remember hearing a rule -- something about tapping depth being twice the diameter of the thread. How many threads need to be engaged for maximal strength? Do these thread properties exist in Machinery's Handbook? Thanks ------- Re: Strength of a tapped #2-56 thread? Posted by: "Clifford Ward" cd_wardx~xxnc.rr.com Date: Wed Sep 5, 2007 10:36 am ((PDT)) Depends on the Female material involved: Aluminum-2x diameter Cast Iron/Brass/Bronze-1 1/2 x diameter Steel- 1x diameter (Data from PM Research catalog...probably also found in some machining book. I did not check my Machinery's Handbook.) These are minimums, but provide an answer to your question. These are the guidelines I use and they have served me well. Cliff Ward Cary, North Carolina USA ------- Re: Strength of a tapped #2-56 thread? Posted by: "JACK SIMS" JACK-BR549x~xxWORLDNET.ATT.NET Date: Wed Sep 5, 2007 11:23 am ((PDT)) If one takes the time to really go through the Machinery's Handbook you can find about 80% of the answers to all sorts of machining questions. I have been using mine since 1966 and am still finding answers to my questions. If you take the time to look it's in there someplace. Jack Sims ------- Re: Strength of a tapped #2-56 thread? Posted by: "Roger Patterson" rlpattersx~xxshaw.ca rogerlpat Date: Wed Sep 5, 2007 12:00 pm ((PDT)) In the 24th edition the formula is given on page 1325. But I like Cliff's rule of thumb. Roger ------- Re: tap hole size [taigtools] Posted by: "Rich Crook" richcrook9418x~xxyahoo.com Date: Sat Sep 8, 2007 4:12 pm ((PDT)) Jim wrote: > > I need to tap a 3/4-16 hole in 6061 aluminum but am not sure what > > size hole I need to bore. Can someone help me on this? Jim D. >11/16" drill for a 3/4"-16 tap, generally speaking... A quick & easy way to figure tap drill sizes: For English threads (threads per inch) subtract the inverse of the pitch from the nominal diameter. Example: 3/4-16 thread - pitch is 16, so the inverse of the pitch (distance between threads) is 1/16 - subtract 1/16 from the dia (3/4") to get 11/16" Metric threads are even easier: just subtract the pitch from the diameter. (Metric thread pitch is already the distance between threads.) This will give you ~77% thread depth, which is what you want for tapping (>80% thread is a lot harder to cut with a tap & often leads to broken or jammed taps.) The drill size can also be fudged up/down slightly to get to the nearest standard drill size. This will work for any "standard" 60 degree included-angle thread pitch. Asymmetric & oddball threads (Acme, buttress, sawtooth, etc) are a whole different story. Note also, this is for *cutting* taps - thread *forming* taps (aka roll forming or cold forming - they don't have flutes) need a slightly bigger hole - you'll need a drill chart/table for these. Rich ------- Re: tap hole size Posted by: "Paul W. Chamberlain" pwcx~xxcapcocons.com Date: Sat Sep 8, 2007 8:05 pm ((PDT)) Here's the site I go to for tap drill info: http://www.precisiontwistdrill.com/techhelp/techhelp.asp Paul, Central OR ------- Re: UNC vs NC [LittleEngines] Posted by: "Donald Qualls" silent1x~xxix.netcom.com Date: Tue Sep 18, 2007 4:01 am ((PDT)) yangwuchenchiaolin wrote: > Can anyone explain the difference between UNC and NC threads? > thanks, David UNC = Unified National Coarse NC = National Coarse Basically, they're two different standards for the same thing. They have the same angles and sufficiently similar top clips that if they're the same pitch and diameter they'll interchange, but in many sizes the standard pitches are different (usually not by much). There are also NF and UNF, of course, with similar similarities and differences. Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com ------- Re: UNC vs NC Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Tue Sep 18, 2007 5:18 am ((PDT)) To expand a bit on Donald Qualls' response: The first standardized thread form was the Whitworth, adopted in England in 1841. The United States in 1864 adopted the Sellers standard, which became the American Standard in 1935. This was a 60 degree Vee form. There was no international standard until the US, Britain, and Canada agreed on the Unified Screw Thread in 1948 (driven by the logistical nightmare created by the incompatible systems during the Second World War). This was a compromise between the American Standard and Whitworth systems and provided interchangeability among threads in all three countries. The crest of the external thread may be flat or rounded, and the root is rounded. Otherwise the form is the same as the American Standard. The International Organization for Standards (ISO) was created in 1946 to establish a single international standard for metric threads. The standard metric thread has a flat crest and root, but the external thread may be rounded. Otherwise the form is similar to the American National and Unified threads. Nonetheless, I have encountered metric fasteners that are incompatible between machine tools manufactured in Germany and Japan, despite their having identical designations, and being claimed to adhere to the same ISO standard. For the home shop machinist, I advise choosing the standard most commonly used in the country where you live. That would be Unified in the U.S. and metric everywhere else. I cannot imagine a design that would suffer from replacing fasteners of any system with similar sizes in any other. Special purpose threads, such as Buttress and Acme, are another subject. And we have not yet touched upon classes of fit, formed versus cut threads, pipe threads, and more. Everyone with an interest in these matters really must have a copy of "Machinery's Handbook" from Industrial Press. As I used to tell my students and apprentices: "If you wake up trapped in a bad science fiction movie, wherein you are marooned on an uninhabited planet, there to recreate Technical Civilization, this is the first book you grab." (Happens to me about twice a month.) DC ------- Re: UNC vs NC Illustration posted Posted by: "David Clark" dcclark111x~xxcomcast.net Date: Tue Sep 18, 2007 5:38 am ((PDT)) see: http://ph.groups.yahoo.com/group/LittleEngines/photos/view/13c0?b=5 ------- Re: Basic 101 die information questions needed answered [taigtools] Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Thu Oct 25, 2007 10:14 am ((PDT)) "f24kdc"wrote: >I broke my die 2-56 Walthers #947-1314. Forced it on a diameter too > big. I am looking to replace it. Not your typical round 13/16" die. F24kdc Name?? No offense but to be blunt, I have yet to purchase a Tap or Die from Walthers, Micro Mark or any hobby store that was not of poor quality. I would suggest that you purchase quality Taps and Dies from a machine tool supply house such as MSC, Travers etc. You can purchase any size, type or style you will need preferably USA made for the best value for the dollar. You can also request a free chart listing all Tap and Die information such as OD`s, drill size, etc. Usable quality 00-90 dies are very hard to find at a reasonable cost. (Generally $75.00-$100.00.) For this reason I switch to 1.2mm metric as a replacement that is almost identical in size and readily available at reasonable cost`s for both quality Taps and Dies. 1.2mm nuts and bolts are also not easy to find but they are easily made with Taps and Dies. Jerry Kieffer -------- Re: Basic 101 die information questions needed answered Posted by: "Geoff Kingma" gkingmax~xxinterlog.com Date: Thu Oct 25, 2007 3:36 pm ((PDT)) I have 0-80, 1-72, 2-56 and 4-40 dies (all 13/16" od) purchased from KBC. I just checked the 0-80 and it was made in Poland. All work very well and are reasonable price-wise - all about $15 Cdn. I am sure they are cheaper from KBC USA. Geoff ------- internal threading question [atlas_craftsman] Posted by: "nathan.bigelow" nathan.bigelowx~xxyahoo.com Date: Fri Oct 26, 2007 6:50 pm ((PDT)) Novice here. The lathe operation manual shows internal thread cutting with the compound rest set at 29 deg. A machining book I have shows the compound rest perpendicular to the center line as do the diagrams in the J&L catalog. Rather than cutting some threads, what should I make of this? Thanks for patience w/ a newbie question ------- Re: internal threading question Posted by: "ahz" ahzx~xxinsightbb.com Date: Fri Oct 26, 2007 7:10 pm ((PDT)) Practice on scrap first :-) ------- Re: internal threading question Posted by: "n8as1x~xxaol.com" Date: Fri Oct 26, 2007 7:18 pm ((PDT)) by setting the compound at 29-30 deg , only the leading flank of the bit cuts. (1/2 the load on the tool) easier , & supposedly cleaner thrds , particularly w/ a LIGHT machine.....early machines had no compound & thrds were cut straight in, BUT they ususally used a gooseneck (FLEXIBLE tool/ holder) this mitigated chatter problems w/ light machines & heavy cuts .....when u do use the compound make sure that the cutting forces are shoving back against the compound taking out the slack to prevent a "drunken" thrd.... if u r just starting , light cuts straight in may be simpler for you to calculate depth .... best wishes docn8as ------- Re: internal threading question Posted by: "William Abernathy" williamx~xxinch.com Date: Fri Oct 26, 2007 10:44 pm ((PDT)) If you have a professional lathe, like a Hardinge or such, which weigh a ton have the bed and carriage flex of a brick, you don't need to worry (not nearly as much, at least) about all the various ways the tool can weasel out of the job you want it to do. Want to cut an inch-and-a-half by eight thread? No problem! Just set the point to reach the minor diameter, engage the power feed and gouge away. For mere mortals who own Atlas and other "hobby" sized lathes, known for their supple beds and yielding carriages, you can't just carve out your threads in a pass or two and be done with it. You need to sneak up on your threads, and a good way of doing that is by setting the compound at 29 to 29 1/2 degrees. When you advance the compound at that angle, you only push one edge of the threading tool into the work, and the lee side of the bit gets to hang out in the "shade" as you advance the cutting edge. You need to cut some threads. And if you're totally new to all this, you need to cut some outside threads first. When you cut inside threads, it's always a good idea to have a male component all ready to screw into the hole you're making. That way, you don't have to unscrew the part to check on it and then try to pick up the thread again. Don't be afraid to make scrap metal -- it's the only way you learn. Or as a certain calligraphy teacher once said, "You got a million bad characters in your fist, and the only way to get them out is to write them down!" William A. ------- Re: internal threading question Posted by: "jerdalx~xxsbcglobal.net" Date: Sat Oct 27, 2007 6:33 am ((PDT)) There is a reasonably good reason for doing it with the 29 degree angle in any case. That is the factor of wear and "drunken" threads. With the angle, and cutting on the advancing edge, the cutting pressure is in a direction to "take up" all the wear in the leadscrew/halfnut/ carriage system. And there IS always some wear and/or looseness. The carriage should follow the helix of the leadscrew perfectly. If it does not, the cut thread won't repeat the exact rate of advance set by the leadscrew. The threads will be inaccurate, maybe enough to actually jam in use. If you advance the crosslide for depth, there is no "bias" to the cutting pressure, since both sides of the tool are cutting. The wear and "slop" are not taken up. As a result there is the chance that hardspots in the work, or just the toughness of the material, can "take charge" and actually push the carriage ahead. In that case, the thread will be bad, "drunken" and out of the correct helix, wherever the carriage was "pushed". The tool path may wander around in the "slop range", and the resulting threads won't fit the nut, etc. Yes, this CAN occur with a larger lathe, when cutting a larger thread. The degree to which the carriage is pushed around will vary with weight, however, and you probably can get away with things on a large heavy machine that are not possible with a very light machine like Atlas, especially if your threads won't be "inspected" by QC. They may be "out" but not enough to fail to work in your application. JT. ------- Re: internal threading question Posted by: "nathan.bigelow" nathan.bigelowx~xxyahoo.com Date: Sat Oct 27, 2007 9:51 am ((PDT)) William, Thanks for the help on this. I've turned into chips all of the suitable scrap around the house here already. And recently purchased some new tube and round stainless and I wanted to be certain in my thinking processes before I sacrificed it away to the learning gods. Thanks again ------- Re: internal threading question Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Sat Oct 27, 2007 10:43 am ((PDT)) Go to the big box home store and get some plastic tubing on which to practice. If I'm doing something with significant cost and good crash potential (like inside threading a blind hole to a shoulder) I'll whack one out in plastic before using the good material. It can help get you into the swing of things (like the cutter retraction is backwards, etc.) before the real work starts. ------- Re: internal threading question Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sat Oct 27, 2007 11:18 am ((PDT)) Oh oh! You want to do internal threading on STAINLESS on an Atlas lathe? While possible, this is not the kind of job to start learning on! Stainless has the awful property of work-hardening. If you cut too fine a chip, the material under the cutter is work hardened, and can become a huge hassle to cut on the next pass. Internal threading is plenty hard enough when not complicated by tough material. Maybe you'd better tell us the diameter and pitch of this thread. It might be a candidate for a tap. The problem with materials that are both tough and susceptible to work hardening is that you have to maintain an agressive feed on every pass of the tool, or there will be no successful next pass. If the material is tough, then you are getting into a narrow "canyon", with cutter vibration on one wall of the canyon and work hardening on the other wall. The margin for making a good cut gets narrower and narrower. Then, when cutting a thread, the width of the chip goes up with each successive pass, as the tool gets deeper into the work. Eventually, either the thread has been completed, or nearly any lathe will begin to chatter. The 29 degree trick definitely helps in difficult threads, but the problem of chatter is still there. Also, with internal threading, you can't support the end of the work with the tailstock, so the threaded part needs to be very close to the chuck. You want the compound slide pulled back so the toolpost is as close to the swivel as it can be, to get the most rigid support. Just a guesstimate from working with Atlas/Craftsman lathes for some years is that if this is about 10 TPI, you probably will not be able to cut it. If it is about 40 TPI, it is not likely to be much trouble at all. Somewhere in the middle, you will find these problems of chatter and work hardening to meet and give you a heck of a "learning experience". Have you ever seen a 150 Lb lathe+table "dance"? I have gotten my 10" Atlas to literally levitate due to vibration on disaster cuts like this. (I now have a 15" Sheldon lathe, about 3000-3500 Lbs. and have cut some tough threads, and it acts like it is cutting soap! It is all about stiffness.) Jon ------- Re: internal threading question Posted by: "carvel webb" carvelwx~xxabsamail.co.za Date: Sat Oct 27, 2007 11:31 am ((PDT)) Nathan - stainless steel can be quite difficult to machine, so if you are looking to experiment, then mild steel, or even better, free cutting mild steel could be easier. If you land up with difficulties in getting the basic technique to work, at least it would not be compounded by the material. Good luck, Carvel ------- Re: internal threading question Posted by: "LouD31M066x~xxaol.com" Date: Sat Oct 27, 2007 11:57 am ((PDT)) Stainless steels are not all equal...some types will be in "possible" range and many others will be very challenging as stated. The average piece of scrap is unlikely to be easily machined. "Stainless Steel" is a generic term that is applied to a wide range of alloys with generally poor machining qualities as compared to the 'free" machining types of carbon steel. As many boaters have found not all "stainless steels" resist corrosion well or at all in marine use and stainless steel nuts and bolts will gall if over tightened...torque wrench is not optional. Louis ------- Re: Quick Question [taigtools] Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Date: Thu Nov 15, 2007 3:36 pm ((PST)) prettejohn wrote:> Hi Guys > I want to hold a tap in the headstock to tap holes in material mounted on the cross-slide and or hold a tap in the tail-stock and tap holes in material held in the chuck. Any suggestions; I know I could hold a tap in a 4 jaw chuck but mine is independent and it seems a clumsy method. regards Alan < You can use a spring loaded tap guide in either, although you might run out of room. In the tailstock I usually just chuck it in the Jacobs chuck, or use the dead center against the center hole in the tap (large taps) or tap wrench. You could use a drill chuck mounted on the 1140 drill chuck arbor to hold taps on the headstock. You could also get some blank collets and drill them out to hold taps, locking them with a tiny setscrew, or some blank arbors for the same purpose. See our homepage at www.cartertools.com/nfhome.html ------- NOTE TO FILE: The following websites hold useful information about standard (and some very odd) thread specifications. This one gives the American unified sizes in a nice colour chart: http://www.sizes.com/tools/thread_american.htm Next one gives the smaller machine screw threads. [Note: the left column Nominal Size & Threads per Inch is a bit too narrow and wraps. The thread names are 0-80 etc.] http://www.smithfast.com/msthreaddims.html For the origins of machine screw sizes try here: http://en.wikipedia.org/wiki/Screw#Unified_Thread_Standard And here is a very useful site when looking for oddball threads for cars or cameras or bicycles or whatever: http://www.gewinde-normen.de/en/index.html ------- Re: Taper Threading. Was Advice on setting up a 4400 [sherline] Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Sat Nov 24, 2007 5:21 pm ((PST)) "wru1941" wrote: > Hi Jerry, Please tell us about taper threading with > the threading attachment. Thanks, Bill Rutiser Bill: With the threading attachment mounted as suggested by the factory (Behind the spindle) the head can be rotated clockwise for taper threading. Depending on the taper you will need to space the spindle gear (Position A ) so it will match the threading assembly. This may also require additional threaded holes for the drive screw (No.3109) to match the location of the spindle Gear. It can also be accomplished with a short key between the drive handle and drive gear. Either way is a very simple setup. The head can be rotated counter clockwise by assembling the train in front of the spindle. Taper threading allows a gunsmith to duplicate some of the older taper threads from screws to breech plugs etc. For other projects it allows one to make special size miniature high quality wood screws that are not available. Very fine minature taper pipe threads are also easily cut with this setup. And the list goes on and on including taper governor drive worms for the very expensive Music boxes. Even some clock fusee`s are possible. The possibilities are only limited by your imagination. Jerry Kieffer ------- BA,BSC, BSB TAPS AND DIES [LittleEngines] Posted by: "hanley_gerald" gbhanx~xxaol.com Date: Wed Dec 19, 2007 7:24 am ((PST)) I'm looking for a U.S. source of British standard taps and dies. Can anyone recommend some vendors? Thanks, Gerry ------- Re: BA,BSC, BSB TAPS AND DIES Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Wed Dec 19, 2007 7:35 am ((PST)) http://www.britishfasteners.com has many sizes. It may be cheaper to order from the UK. Take a look at http://www.tracytools.com/ ------- Re: BA,BSC, BSB TAPS AND DIES Posted by: "Ed Bratt" brattx~xxsasktel.net Date: Wed Dec 19, 2007 7:45 am ((PST)) Gerry: Newman Tools has British Standard. You will find a US branch listed on their site: http://www.newmantools.com/tapdie.htm Ed Bratt Regina, Saskatchewan ------- Re: BA,BSC, BSB TAPS AND DIES Posted by: "brian458666x~xx550access.com" Date: Wed Dec 19, 2007 8:30 am ((PST)) There is a seller on ebay with some, and I have bought from this seller with very good results. The name is "giftable". I don't know that they will have what you want, but if you take a look... Brian ------- Rare threaded fasteners Posted by: "James W. Early" j.w.earlyx~xxworldnet.att.net Date: Wed Dec 19, 2007 9:23 am ((PST)) Rather than search for rare and expensive fasteners and threading tools I prefer to use this substitution chart to select cheap and available local ones. With this chart it is easy to see what is called for in the drawings and pick an available off the shelf local item. JWE Long Beach, CA ------- Re: Need info to reproduce parts on Logan 8" vertical feed.[Metal_Shapers] Posted by: "Alan R. Lapp" alanlappx~xxlevelfive.com Date: Tue Jan 15, 2008 6:21 am ((PST)) On Jan 14, 2008, at 8:04 PM, a7mmremmagman wrote: > I also need to build a new bronze nut for the crossfeed on the table > very soon. The one that is on it has threads that are paper thin. > Would anyone know if I could rent the 5/8" 10tpi Left Hand tap that I > need for this project? I would rather not fool with threading this nut > in the lathe if I can avoid it. McMaster has the taps, but the price > scared me off. I'm in favor of building a tap set. It's my understanding that Acme threads (commonly used on lead screws) often have two roughing taps and a finishing tap. Check in "Machinerys Handbook" for the thread forms of the roughing taps. I'd suspect that the first tap is a standard "V" thread form, and the second rougher is nearly a full-form Acme shape, and the final just shaves a couple thou off to make a good finish. Basically, if you can make male threads on a lathe, and have a propane/ mapp/oxy acetylene torch, you can make taps. The question is one of how to cut the slots. If you have, or have access to a mill, great. If you don't it's possible to put a milling cutter in a lathe, and use the cross slide to feed into the cutter. Grinding works better, but if you carefully clean up the slots with a needle file before hardening, a milling cutter works fine. On the occasions I've made a tap, I cut a "proof" hole in aluminum first, just to ensure that it works as intended before cutting into the "real" work piece. Here's a couple links. http://www.practicalmachinist.com/vb/showthread.php?p=804181 http://www.practicalmachinist.com/vb/archive/index.php/t-126394.html ------- Re: Need info to reproduce parts on Logan 8" vertical feed. Posted by: "n8as1x~xxaol.com" n8as1x~xxaol.com Date: Tue Jan 15, 2008 6:40 pm ((PST)) the brits/canadians frequently cut acme & square thrd with an undersize bit ( correct form ,tho ) using the x slide , the compound set at rt angles to the xslide ...after correct depth is reached, the compound is moved a few thou at a time rt , & left till the screw / nut fits to ur specs...this avoids having to grind the bit XACTLY dead on ...just need the angle correct .... i have cut as small as 7/16 X 10 internal sq thrds this way & will not cut a sq. thrd any other way ....FWIW ..if fitting a nut to an original screw , u shud take a cleanup cut on the screw to get it the same size thruout , otherswise , u must leave some slot for the unworn areas. best wishes docn8as ------- Re: Need info to reproduce parts on Logan 8" vertical feed. Posted by: "Clive Foster" clive_fosterx~xxtalk21.com Date: Wed Jan 16, 2008 3:29 am ((PST)) Further to the information from docn8as, my friend John used this method to cut feed nut threads and feed screws when he was working for the company that made the CVA precision lathes. Zero backlash was good enuf! I'd be vary chary about using sets of acme taps as it's much, much harder to get a true running, accurate thread than with a conventional tap. Especially in the tough metals favoured for feed nuts. John tells me that the bean counters decided that his way was too slow and expensive so they purchased a set of 5 (?) taps at vast expense (against engineering advice) to do the feed nuts starting with a plain drilled hole. I gather the machines were set up and 6 months worth of feed nuts done in a day or so. Bean counter very happy. Shortly afterwards they tried to use them. None were sufficiently true to be used straight out of the box. After a deal of (very expensive) hand fettling and selective assembly, the first two or three were made to fit and found insufficiently accurate. Managing director very unhappy. Bean counter and his management advocate now jobless. John went back to cutting threads his way. John reckons that the taps could have given satisfactory results but would have to have been entered into a thread already roughed out on the lathe in an unfinished nut blank. Then the assembly would have to have been fixed to an oversize true running threaded mandrel so that the outside of the nut could have been machined true to the thread. Finally the screw thread would have to have been cut to match the nut. Rather the long way round. Clive ------- Tapping Guide [sherline] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Fri Jan 18, 2008 3:56 pm ((PST)) Hello Group. Here's a useful design for a tapping block: http://tech.ph.groups.yahoo.com/group/sherline/photos/view/d71e?b=1 Throughout all of the machining operations to produce this piece - turning, facing, drilling, and boring on the lathe; followed by milling on the rotary table, the work was held exactly as you see here: http://tech.ph.groups.yahoo.com/group/sherline/photos/view/d71e?b=2 No steady rest, live center or other support. The work was never removed from the chuck. No loosening, no re-tightening, no problems. Clearly, some of us are finding our Sherline 3-Jaw chucks good for more than paper weights. I'd still like to understand why others are not, and am still willing to work with anyone on this problem. Looking forward to Cabin Fever tomorrow: http://cabinfeverexpo.com/ Hope to see some of you there. Best regards, DC ------- Re: Tapping Guide Posted by: "Dave Hylands" dhylandsx~xxgmail.com Date: Fri Jan 18, 2008 4:48 pm ((PST)) Hi DC, Very nice. I especially like the idea of using the brass inserts. I've done a much simpler version here: Only takes a couple minutes to crank one out. The same tapping black can be used for #0, #2, and #4 (maybe #6 but I can't remember). Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ ------- Re: Tapping Guide Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sat Jan 19, 2008 9:52 am ((PST)) Hello, I've uploaded some pics on my take on the tapping guide idea. They are in the photo folder called 'tapping guide'. The device is simply machined from a large bolt and I make one for each size that I need which is less fiddly than using little bushes (although one size bore will fit several different taps - especially in the small sizes). This is because of the way I organise my tools. I have a little box for each thread size holding the taps, die, clearance and tapping drills, plus a guide. I stamp the thread size on one of the bolt head flats so that it is easy to sort them out when several are on the bench at the same time. Ian ------- Re: Tapping Guide Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sun Jan 20, 2008 8:30 am ((PST)) DA Dossin wrote: > Ian, An interesting solution to a problem. > Did you think this up yourself? Dan Hello Dan, No, I cannot take any credit for this idea. I copied the concept from a very old and experienced toolmaker who I worked with when I first went into the engineering business. Except his guides were lovingly made, with a flat milled into the stem which was engraved with the size of the guide bore and the owner/s name. They were fitted into a beautiful wooden case and I'm sure they were all hardened and lapped to size. I just had a big bag of old bolts and a job to do in a hurry. Ian ------- Darn! Broke a tap... [sherline] Posted by: "Tom Bank" trbankx~xxpaonline.com Date: Sat Jan 26, 2008 7:46 pm ((PST)) Let's see, for a broken tap in brass you can oxidize the steel away with alum solution, can't you? But does that work with aluminum? Or does the aluminum sacrifice itself faster than the steel? If that doesn't work, is there anything that will remove my broken tap? Other ideas that come to mind are drilling it out. Would a carbide drill work on a tap? Or can I grind it out? And if the later, what should I use to grind it with, diamond? Then there is always the last resort, cutting teeth in the end of a steel tube and using it to take out a core, then making a plug and starting the hole over again. I should say that the tap is 6-32. Any helpful tips? Thanks in advance, Tom Bank ------- Re: Darn! Broke a tap... Posted by: "Marcus" implmexx~xxaxionet.com Date: Sat Jan 26, 2008 8:14 pm ((PST)) Taps can be drilled out easily with carbide drills. That's how I usually remove them, even though I've got an EDM. Cheers Marcus ------- Re: Darn! Broke a tap... Posted by: "Corndodger" corndodger2x~xxhotmail.com Date: Sat Jan 26, 2008 8:57 pm ((PST)) Some say you can "easily" drill out a tap, but that's not my experience. You'll end up with a hole too big and a wasted afternoon. If there is any wiggle room from the top of the tap that can be gripped in any way, I'd say try heating your brass. THEORETICALLY, it should expand faster than the tap, and you might be able to work it loose, then out. If you're going to try drilling it out, do it with a "backwards" drill or milling bit, plus the heating. If you're lucky it might grab and extract it. I've not had great experience removing taps and have, on occasion, ground them down flat and moved to another hole. Last summer I had a devil of a time with Hanson taps, available from your friendly ACE Hardware store. I think I went through 3 of 6-32 and two of 8-32. Sure, they got replaced for free, but I was terribly inconvenienced. My guess is they are being imported instead of made in the USA. Jim ------- Re: Darn! Broke a tap... Posted by: "Jim Ash" ashcanx~xxearthlink.net Date: Sat Jan 26, 2008 9:56 pm ((PST)) If it's a 2-flute tap, sometimes you can jam a couple sewing needles down the flutes, grip them with pliers and turn out the remaining piece. Jim Ash ------- Re: Darn! Broke a tap... Posted by: "shawn c" shawncd1x~xxmsn.com Date: Sat Jan 26, 2008 10:13 pm ((PST)) Stick a slightly oversized hex nut over the tap and use the mig welder to filler up. Making sure to start your arc on the busted portion of the tap and work your way up until you fill the nut with weld. Let it cool down a little, and unscrew. This works great for busted bolts also. The heat also helps to loosen its grip, especially if there's loctite present ;-) ------- Re: Darn! Broke a tap... Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sun Jan 27, 2008 1:10 am ((PST)) Hello Tom, Alum works with steel in aluminium - so I'm told (never used it anywhere to be honest, but I never let my inexperience stop me from giving advice!). I always use carbon steel taps - compared to HSS they stay sharper for longer, cost less (in the UK) and you can soften them at a sensibly low temperature to make it easy to drill out any broken ones. Of course this is probably no help to you at all if you are using HSS. Ian ------- Re: Darn! Broke a tap... Posted by: "montanaaardvark" boblombardix~xxcfl.rr.com Date: Sun Jan 27, 2008 12:28 pm ((PST)) Speaking of stuck taps, I've had a broken off 10-24 tap in a piece of stainless since I got started in this hobby - in 2003? Would alum work on a steel tap in stainless? Thanks, Bob ------- Re: Darn! Broke a tap... Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sun Jan 27, 2008 12:36 pm ((PST)) Hello Bob: The alum works by attacking the iron component of the steel tap, so it is only a usable method if the tap is stuck in non-ferous material. Ian ------- Re: Darn! Broke a tap... Posted by: "Marcus" implmexx~xxaxionet.com Date: Sun Jan 27, 2008 5:14 pm ((PST)) Hi Ian: I'm surprised that you find carbon steel taps stay sharper longer than HSS; I and most others have had the opposite experience. In fact, HSS was developed to address some of the shortcomings of plain carbon steel cutting tools, notably, their poor hot hardness and low wear resistance. Your point about being able to soften broken carbon steel taps is a good one however. Cheers Marcus ------- Re: Darn! Broke a tap... Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sun Jan 27, 2008 11:24 pm ((PST)) Hi Marcus: Yes, you are right in that HSS is better at high temperatures, but I only use taps by hand, not at high speed so this is never an issue. At 'low' temperatures (and under the gentle forces of hand use) CS does wear better. There is only one reason for choosing to use HSS taps and that is due to the manufacturing process rather than the material properties: CS taps are made by cutting the blank using a master die, grinding the flutes, then heat treating the tap to harden it. Although the heat treating is done under careful control, it will introduce some small amount of distortion. This means that you will have problems if you try to re-sharpen the tap in a tool and cutter grinder. HSS taps are made by grinding the threads into a fully hardened blank. This means the thread is always accuate to the centre of the tap (and is likely to be a more accurate thread generally - but QC comes in here so this is a theoretical point). This means you can resharpen the tap by mounting it on the centres at each end. The inherently more accurate thread on HSS taps may be important if you make micrometers, but otherwise all taps are made to some sort of standard of accuracy so this is not something I worry about. As for resharpening - I do not have a T&C grinder so I'm not concerned with this activity (the best my taps get is the occasional touch with a little slip stone). In fact I grind the centre point off the end of most of my plug (bottoming) taps anyway, so they can reach as far down blind holes as possible. Ian ------- Re: Digest Number 3644 (Re: Darn! Broke a tap...) Posted by: "Jeff Demand" jdemandx~xxgmavt.net Date: Mon Jan 28, 2008 1:07 pm ((PST)) Ian, and Bob: I don't use the alum technique but have used Sparex (jewellers pickle) also sold as Ph Down for swimming pool Ph adjustment. All of the stainless I used was completely untouched. The corrosion resistance of stainless is often improved by passivating... 30 minute dip in warm nitric (20%) or citric acid (10%) solution. Granted the sparex (sodium bisulfate) is an sulphuric acid analogue but it seems to also passivate stainless. Strange things happen when you mix chemicals or metals together, the properties of the mix are usually different than the ingredients. Think about table salt, NaCl is fine in the kitchen but not sodium metal nor chlorine gas. Jeff ------- NOTE TO FILE: This next conversation involves a newcomer to threading using a lathe, and the problems he encountered. Note that the thread being attempted is 55 degrees, hence his topslide setting of 27.5 degrees. He is basically trying what is a common practice in North America -- using the topslide for all advancement into the cut, and thus attempting to cut only on the left flank of the V-thread. What many in N.A. do not realize is that cutting straight in is a common practice in many machine shops, where time is money. During this conversation you will see how that method can be modified slightly to produce a very clean thread. Note carefully the warnings about the shape of the bottom of the "V". The different approaches to threading on a lathe were brought home to me one month when I received a copy of Home Shop Machinist detailing the common (here) topslide method, and also received a copy of Model Engineers Workshop with an article by a retired machinist advocating the straight in method. Why not try both methods on scrap and see which you prefer? ------- Re: Sticky Topslide [MyMyford] [Now about threading on the lathe.] Posted by: "taylor_pg" taylor_pgx~xxntlworld.com Date: Tue Feb 5, 2008 5:53 pm ((PST)) Thanks Stephen, I think I may have discovered the problem this evening. After completely removing the gib strip to eliminate that as a factor, I replaced the slide on its dovetail and it was still stiff. The topslide leadscrew screws into a replaceable insert secured with two screws. The insert is made of... aluminium. I think the aluminium has oxidised and 'grown'. I removed the insert and tried to screw it on to the leadscrew by hand but it was too tight to screw it beyond a couple of threads. This has provided me with a nice little project, namely manufacturing a replacement insert using brass. One way or another I'm going to become proficient at threading... The good news is that the drawbar is finished and my Clarkson Autolock milling chuck is now useable. The bad news is that I hand threaded the ends of it and I have therefore not advanced my proficiency in using the lathe for cutting a thread. I did try though. This brings me to a question for you experts... Having discovered what I think is the problem with the stiffness in the topslide, I decided to carry on regardless with my exercise. I replaced the gib strip, mounted the topslide in place and angled it to 27.5 degrees, fitted a 55 degree thread form tool at centre height and checked that it was properly at 90 degrees to the workpiece using a thread template. I advanced the tool to just touch the workpiece, backed it off 20 thou. with the cross slide and advanced into the workpiece using the topslide. I engaged the half nut and off we went. When I reached the clearance gap I disengaged the half nuts, backed the tool off 10 thou using the cross slide, wound the carriage back to the start and repeated the process. I didn't need to refer to the thread indicator because it was a 16 tpi thread and the main leadscrew of the lathe is 8 tpi. Please correct me if I'm wrong but any multiple of the pitch of the leadscrew will always engage in the right place. Everything went well for the first three passes and then the fourth pass removed the newly cut thread and left me with a plain mandrel again. (Please stop laughing, you at the computer!) This is my question... I accept that the tool will always engage at the correct place if you only use the cross slide to move it directly out of the thread and back in again but how do you ensure that it does so when you use the topslide to advance it at 27.5 degrees to the axis of the workpiece? Am I winding the topslide in from too far away? Peter ------- Re: Sticky Topslide Posted by: "tr0up" tr0upx~xxyahoo.com Date: Tue Feb 5, 2008 11:54 pm ((PST)) "taylor_pg" wrote: big snip > .... I set the topslide to 27.5 degrees and recalled that the > technique of threading calls for 'advancing the topslide and > retracting the cross slide', and wound the topslide out to provide > enough movement for the process. Peter: Setting over the topslide to half the thread angle is one way of achieving a better result, but when you are cutting your first threads, it may be introducing a potentially confusing factor. I'd be inclined keep things simple by leaving the topslide at 0 degrees for now, so that all depthing is done with the cross slide index. The disadvantage of this is that the V tool cuts on both flanks, which can limit the amount you can prudently take off in each cut, once you get to a substantial proportion of thread depth. Once you gain a bit of familiarity with the process (which doesn't take long if you keep things simple, you can alleviate the 'crowding' of the two chips into each other, by simply moving the tool sideways using the topslide, just a smignen with each new cut. Because the topslide is parallel to the work axis, this will not influence the depth. There is a mathematical way of working out how far to move it sideways (in proportion to depth of cut) but in practice you can actually get a feel for this by waiting until the cut begins and then simply winding the topslide leftwards until there is only one chip coming from the leading flank of the tool. Note how far you moved it, as a proportion of the depth of that cut, and this will be the amount for that pitch forevermore. Reduce the pro-rated amount slightly on the final cuts, so both flanks of the threadform will be cleaned up. These cuts will be shallower, and ultimately "spring cuts" (ie theoretically no depth of cut, in practice the work and the lathe will progressively surrender the accumulated deflection) This incidentally is how "Martin Cleeve" (actually Kenneth Hart) the all-time guru of Myford screwcutting -- who made a living cutting tricky threads on a production basis on his heavily self-improved Myford -- ended up handling the issue of how to cut the cleanest threads in the least time and fuss. (Except he calculated the offset, rather than my more empirical method) In the interests of keeping it simple, it is an excellent idea to practice initially cutting threads whose pitch is a multiple of 8 tpi. This means you don't need to use the threading dial at all - one less thing to watch. For a somewhat simplified set of rules for which threads can use which stations on the dial, refer to the Myford manual in the "Files" section. IF you can't be bothered, just always use the same number; as long as you're not cutting BA or other metric pitches, this will always work, and doesn't take much longer unless you're cutting really big threads. Remember that unless you stone the correct radius on the tip of the V tool (and who's going to do that afresh for every different pitch?) your tabulated or calculated depth of thread will be too shallow. If you don't have a female thread to use to check the fit at the end of the job before you call it finished, you'll need to do a calculation to account for the difference in penetration between a sharp V and the correct radius tip. ------- Re: Cutting Threads [atlas_craftsman] Posted by: "Lawrence Sciortino" las1940x~xxcomcast.net Date: Wed Feb 20, 2008 11:58 pm ((PST)) On Feb 20, 2008, angelo4967 wrote: > I've cut a few threads that were the full length of the stock between > centers BUT > When you want a thread to end at a certain location, how do you manage > to stop the feed and retract the tool bit precisely at the same spot > with every pass? thanks, Angelo Angelo, great question, it has puzzled me in the past that so little is written about that very detail. Here are some basic details that I think should help get you started, and you will find that as you gain experience with threading, you will develop your own favored methods. Assuming you are using a very basic lathe: There are many ways to terminate a thread, the simplest being to cut a channel to the full depth of the thread with a parting tool at the termination point. Then, you just retract the tool using the cross slide when it reaches the end of each pass. The width of the channel will give you time to do the retraction. You also disengage the split nut, assuming you have a threading gage on your lathe with which to register the beginning of your next pass, but remember, before disengaging you do your cross slide quick retract maneuver. To make a thread without a precut channel, like a commercially made thread or as most professionals would cut, you must know exactly where the termination point is as you are nearing the end of each pass, so that you can rapidly and accurately retract the cross slide and not have the tool dig in. Some fancier lathes have an auto retract function that removes the problem, but with the more basic machines, you've got to devise an alerting method that works for you. A simple method is to simply trace a ring around the material with a pencil or other marker, and when the point of the tool reaches the line, you do the rapid retract. A strip of tape banded around with the right edge of the tape at the termination point may be easier to see on some stock. The key to the technique is to have a very slow speed of travel when you near the end of each pass, so that your eye/brain/hand time fits the time available. A variable speed drive is golden when you're cutting threads, as you will appreciate. Lacking that capability, set your speed very slow, using the back gear if you have that feature. Do some practice threads at varying speeds to learn what you are comfortable with. I have a variable DC drive and find that for the last couple threads as I approach the termination, I've got the speed dialed down really slow, like 20 RPM or less. There are as many ways to signal the retract time as there are imaginative craftspeople, and in discussions with others you will get endless tips. I once rigged up a low voltage light system that comes on when the carriage reaches the desired point. When the light bulb comes on, I retract. I doubt it is original. That works fine too, but is still dependent on one's reaction time, so again, the slower your running speed, the more exact will be the forming of the thread end. I hope this gives you some new ideas, and if you have specific questions, feel free to ask, on group or off. Good luck, Larry ------- Re: Cutting Threads Posted by: "azbruno" azbrunox~xxyahoo.com Date: Thu Feb 21, 2008 8:18 am ((PST)) Cutting a thread landing groove is definitely the easiest as it will provide a clean end while also giving time to react. All that's needed is to disengage the half-nuts in the landing area. The tool needn't be retracted until moving the carriage back. As for triggering on carriage location, it's much harder to get a clean end. If the compound is set at about 30 degrees, then each pass will actually have the tool further along the part at the ending carriage position, and the tool will also be deeper. In order to look cleaner, you need to retract the tool at the right speed to allow the thread groove to gently taper up to the surface of the work. Easier said than done. I often do multi-start threads without a landing groove. What I usually do is when all the thread leads are done, I lock the carriage at the end point and with the tool retracted, I gently bring it in to clean the thread ends. Sometimes it works well, but with some softer materials (e.g. acrylic) it can still leave a bit of a rough edge. Alternatively, I might try to manually crank while retracting the tool at the end to get a cleaner thread. I need to do that for each lead and also make sure the ends are equally distributed around the part. I would like to figure out a better way. Bruno ------- Re: Cutting Threads Posted by: "jmartin957x~xxaol.com" Date: Thu Feb 21, 2008 9:34 am ((PST)) If you have a groove cut at the end of the thread, you don't have to worry about retracting the cross slide quickly. Throw out the half nuts when the threading tool is in the groove, then retract the cross slide at your leisure. Just remember to do it before you wind the carriage back. When cutting internal threads, you pretty much have to use the relief groove method. They are much easier if they run all the way through. John Martin ------- Re: Cutting Threads Posted by: "Lawrence Sciortino" las1940x~xxcomcast.net Date: Thu Feb 21, 2008 10:04 am ((PST)) Angelo, glad it helps. Automatic half nut disengagement would be convenient, but a more important function would be automatic cross slide withdrawal - which needs to take place spot on - the half nuts can usually wait a moment. Ideal, of course is automation that both withdraws the cross slide and disengages the half nut simultaneously. Which you can have by handing over boxes of money for that pedigree of lathe. Hardinge makes a popular tool room lathe with that capability, among others. Someday, maybe... regards, Larry ------- Re: Cutting Threads Posted by: "angelo4967" angelo4967x~xxyahoo.com Date: Thu Feb 21, 2008 10:19 am ((PST)) Thanks to everyone for their great replies. Angelo ------- Re: Cutting Threads Posted by: "Lawrence Sciortino" las1940x~xxcomcast.net Date: Thu Feb 21, 2008 10:28 am ((PST)) John, agreed that you can just disengage the half nuts if the tool is entirely within the pre-cut channel, but when cutting course threads with their greater relative depth, the cutting tool width may exceed the channel width before full thread depth is reached, unless an appropriately wider channel is pre-cut. If the channel is used as a visual marker at which point the cross slide is withdrawn, the channel width is not ever critical. It's possible to do either way, but I've found tool withdrawal first is the safer method. Larry ------- Re: Cutting Threads Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Thu Feb 21, 2008 10:33 am ((PST)) angelo4967 wrote: > When you want a thread to end at a certain location, how do you manage > to stop the feed and retract the tool bit precisely at the same spot > with every pass? You can't. The usual technique is to cut a narrow groove to the full thread depth at the stop point. Depending on the thread pitch and the threading RPM, you can make the width of the groove wide enough to suit your reflexes. I did some threading on a 1"-20 thread on my Sheldon at 900 RPM! It has a VERY precise and easy drop-out of the half nuts, unlike the Atlas, which sometimes requires strong force to release the nuts under load. This groove is a stress concentration, of course, and in some cases is undesirable on a highly stressed part. In that case you just have to pull the nuts out or back out the cutter infeed when you hear the lathe load up. At lower speeds, that isn't a real problem. Jon ------- Re: Cutting Threads Posted by: "catboat15x~xxaol.com" Date: Thu Feb 21, 2008 10:40 am ((PST)) Sometimes when trying to end a thread when you don't have or want a "run out" groove in the work you simply cut off the motor when near the end and turn the chuck by hand for the that last couple turns. Some people have fitted a crank into the spindle at the left end (expansion plug) and finish off a thread that way. ------- Re: Cutting Threads Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Thu Feb 21, 2008 10:45 am ((PST)) angelo4967 wrote: > I might look into rigging up a linkage to disengage the half nuts My 15" Sheldon has a kick-out linkage built into the apron that will disengage either the carriage feed or the threading feed when the apron hits a stop. (This is also part of an interlock that prevents conflicting feeds from being engaged at the same time.) The late-model Sheldon R15 has separate drives for feed and threading, through a keyed drive shaft separate from the leadscrew. The threading feed is pretty normal, but is engaged by raising a heavy lever and locking it in the "up" position. The trip mechanism pulls out a pin and allows the threading handle to drop sharply from it's own weight. A gentle tap on the handle will also drop it out at any time you desire. I didn't get the micrometer stop unit with my lathe, and haven't needed it enough to make one, yet. The carriage feed (and power cross-feed) are through a set of adjustable plate clutches, so you can set them to slip if anything goes wrong. This avoids massive damage to the machine in the event of a crash. The power carriage feed is engaged through a similar mechanism of raising a locking handle that will trip off when the carriage hits the stop. I think working this sort of feature into an Atlas would be a bit harder than a simple linkage that bumps the half nut lever when the carriage reaches a stop. You want a sharp release of the nuts, rather than a gradual easing out. That will wreck the threads on the half nuts, I fear. Jon ------- Re: Cutting Threads Posted by: "ahz" ahzx~xxinsightbb.com Date: Thu Feb 21, 2008 1:14 pm ((PST)) If you don't want to use the 'landing zone' technique common to hand-threading, can you not start all the way to the left (use your threading indicator and an indicator if necessary), and run the carriage rightward? Craftsman 12" have that darned handy reverse gear tumbler. ------- Re: Cutting Threads Posted by: "Lawrence Sciortino" las1940x~xxcomcast.net Date: Thu Feb 21, 2008 2:04 pm ((PST)) yes, you can. that's how you make a left hand thread. ------- Re: Cutting Threads Posted by: "Lawrence Sciortino" las1940x~xxcomcast.net Date: Thu Feb 21, 2008 3:47 pm ((PST)) On Feb 21, 2008, at 3:02 PM, ahz wrote: > I'm not seeing it. If the spindle is still turning the normal > direction, and the cutter follows the same path as it would have, but > left-to-right, I don't see a left-handed thread happening. If I were > threading the normal way and cut R-to-L to the 'landing zone', stopped > the lathe, and reversed the leadscrew direction, the cutter would > follow the same threads I just cut. > (But if I am correct, I don't see how to cut LH threads on my lathe.) > I think my brain just 'sploded. Your brain seems ok, don't worry. Thinking about these things away from the machine is sort of like rubbing your belly and patting your head. You cut left hand threads from left to right, with the spindle in normal rotation and lead screw moving the carriage to the right. Try it to see. A quick way to test such thread questions is to chuck up a piece of white PVC tubing, or other easily traced upon thing, and do the check moving a pencil like a cutting tool. If you actually want to cut a right hand thread from left to right, the spindle rotation must be reversed, and if your cutting tool is still positioned at the front of the workpiece, it must be mounted upside down. All possible to do, just unconventional and not the favored vector for the compound and cross slide to transfer pressure to the lathe bed. If you have carriage and compound provision to do all work from the back side of the lathe, that would be better, but since our little lathes aren't readily adaptable for that configuration, the normal right to left cutting for right hand threads prevails. Larry ------- Re: Cutting Threads Posted by: "angelo4967" angelo4967x~xxyahoo.com Date: Thu Feb 21, 2008 4:51 pm ((PST)) I'm really glad I asked this question. We're all getting a lot of info here. Angelo ------- Re: Cutting Threads Posted by: "jerdalx~xxsbcglobal.net" Date: Thu Feb 21, 2008 6:54 pm ((PST)) You flip the half nuts with your right hand, just after you retract the tool a turn or so with your left on the crossfeed. You can get good enough to make a very nice-appearing thread with surprisingly little practice, if you simply make that your preferred method of cutting threads. You just get the rhythm of the end of the thread passing, and watch the tool as it moves along the thread. You sort of "count down" the turns, and on the last one, you do it. If you retract at a pretty consistent rate, you will get a nice-appearing thread end. Classy, with a "professional" appearance. Naturally, you need to know where you 'were" so you can return the crossfeed to the correct depth. A small error can mean a very different cut on the next pass, since a few thou can be twice your desired cut depth. There are a lot of "easy shortcuts" for slightly more difficult jobs. But it is usually best to learn the harder appearing way, so that you can do it when you need to. After all, you can always "learn" to do the easy way. The easy way is easy to learn, it's the harder way that takes the practice, and there are cases where only the harder way will work. There is a retracting toolholder kit at "Metal lathe accessories", which retracts with a lever flip. That is a nice way to do it, with the advantage that you needn't keep track of your retraction turns or dial position. Use of a "threading stop" is also a good way, which likewise does not require keeping track of the dial position. You just crank in again to the stop, using the compound to feed (which you should do anyway, on a lightweight lathe). A number of expensive industrial machines have a built-in threading stop in their dial system. JT Re: retractable toolholder for threading Posted by: "audi200qpilot" las1940x~xxcomcast.net Date: Thu Feb 21, 2008 9:21 pm ((PST)) JT, I was not aware of the lever operated retractable toolholder you mentioned, do you have any contact info on how to source that item? It sounds like it might be useful to me, but I could find nothing about it when searching "metal lathe accessories". Any info would be appreciated. Larry ------- Re: retractable toolholder for threading Posted by: "EARL BOWER" earl.bower1x~xxverizon.net Date: Fri Feb 22, 2008 6:12 am ((PST)) JT: Try www.sc-c.com/metallathe/index.htm then look for the Quick Retracting Tool Post near the bottom. I have one of these on my South Bend. Earl Bower www.bowermachineandtool.com ------- Re: threading... [atlas618lathe] Posted by: "S or J" jstudiox~xxtbaytel.net Date: Wed Mar 5, 2008 11:55 am ((PST)) "Dan Margolien" wrote >I have not cut any threads yet, but here is something I hope can be done: I have some parts that the male threads are damaged, but mostly there. I have tried to use a jewelers file to fix them, but so far the mating piece is still fighting. Is it possible to set the lathe so that I can synchronize the thread cutting with the original threads? There are only 4 full threads, around 26 TPI. < Hi Dan: Sometimes the lathe is not the simplest or even a necessary tool for a male thread small repair job. While a jeweler's file can come in mighty handy, significant thread damage is more easily tackled with a specialty thread restoration tool. One such tool I really use and like is the "8-in-1" Thread File that claims: "RESTORES DAMAGED EXTERNAL THREADS IN A JIFFY! ANY DIAMETER ........ RIGHT OR LEFT HAND". A pair of these files work really well. No. 1 does TPI 11, 12, 13, 14, 16, 18, 20 and 24. No. 2 does TPI 9, 10, 12, 16, 20, 27, 28 and 32. Vendors include KBC Tools: http://www.kbctools.com/ 26 TPI unfortunately is not on those lists, but KBC sells a Universal Thread File which has a single 60 degree edge. Another thread repair tool that does multiple thread crests at the same time has the cutters on flexible fingers to automatically adjust to different threads. How well that works I do not know personally. Vendors include Lee Valley Tools which has a "Universal Thread Restorer". http://www.leevalley.com/ This one looks to be limited to max thread diameter of 1/2 inch and costs far more than all the files mentioned before added together. Hope this info helps someone. Steve -- in Thunder Bay, Ontario, Canada Machining and Metalworking at Home http://www.janellestudio.com/metal/ ------- Re: Working with Stainless Steel [atlas_craftsman] Posted by: "jmartin957x~xxaol.com" Date: Sat Mar 15, 2008 11:11 am ((PDT)) Mr_Billx~xxmailcity.com writes: > I am about to attempt to cut threads in some 3/4" 304 stainless steel > bar. Can anyone pass on some hints? I will be cutting metric threads > 1.0 so that's fine. What about spindle speed, coolant tools etc. Yes > I am fairly new and have enough stock to practice on. Thanks Bill Hints? Well, unless it absolutely has to be 304, trade it in on a bar of 303. There's a machinist's ditty that runs "303, she's for me, 304, she's a whore". John Martin ------- Re: Working with Stainless Steel Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sat Mar 15, 2008 11:17 am ((PDT)) The big trick with most stainless alloys is to keep a steady feed up through the last cut. If you ever back off on the advance each cut it will work harden and you'll have a big mess. So, when you get close to the last pass, you need to adjust the infeed amount so the last cut comes out at the right thread diameter without the luxury of taking a couple fine passes at the end. You have the problem that the lathe isn't as rigid as you might like for this tough material. I'd probably cut it in two passes on my Sheldon. You may be forced by chatter to do it in 3 or even 4 on the Atlas, but limit it to as few as you can get away with. My calculator says 60-80 SFPM for HSS tools and 175-200 for carbide, or 300-400 RPM for HSS and 900 RPM with carbide. If the bar needs to hang out of the chuck a long way (more than an inch or two) then use the tailstock center. Jon ------- Re: Miniature Taps [sherline] Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Fri Apr 25, 2008 3:32 pm ((PDT)) "Bob Breslauer" wrote: > I am looking for a source for miniature metric (UNM) taps in the 0.8 to 1.2 mm range... plug, bottoming, HSS, carbon steel - whatever. There are some VERY inexpensive sets out there manufactured in India which are also VERY poor in quality. Any Sherline Group members have a good source? Thanks in advance! BB Bob: Serviceable quality 1.0mm and 1.2mm Taps and dies can be purchased from Travers. They are at www.travers.com The only .8mm taps and dies of serviceable quality that I am aware of are from Bergeon (Swiss). However they are a little expensive. One source on the web who generally has them in stock is Otto Frei. They are at www.ofrei.com They can be found under watchmakers tools. Or of course you can make your own. Jerry Kieffer ------- Re: Miniature Taps Posted by: "Denis Jahn" dojahnx~xxprodigy.net Date: Fri Apr 25, 2008 6:20 pm ((PDT)) Bob. Here are a couple of sources: 1. Small Parts Inc. (Florida) 800-220-4242 www.smallparts.com 2. Timesavers (AZ) 800-552-1520 www.timesavers.com ($20 min) 3. Metric Screw & Tool Co.(MA) 800-638-7421 www.metricscrew-toolco.com ($unknown minimum) If you go below 1.0mm you're into watch sizes. ------- Re: Miniature Taps Posted by: "Willard E Wheaton Jr" wwheatonjrx~xxverizon.net Date: Fri Apr 25, 2008 6:59 pm ((PDT)) Jerry, I would like to know the best technique for making the cutting edges on these small taps. I assume you create a threaded blank, with the desired thread. What is your next step? I seem to recall from somewhere, you could harden the threaded blank, and then grind the end in a wedge shape, going from one side, diametrically across to the opposite side, for a length of 3 or 4 times the thread diameter. I have also thought about grinding 3 flats in an equilateral triangular pattern, but worry about the cutting edge angle not producing a cutting edge. Comments on your technique will be appreciated. Willard E Wheaton Jr. ------- Re: Miniature Taps Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Sat Apr 26, 2008 10:43 am ((PDT)) Willard: Over the years I have had a number of commercial taps that have had flats ground on them. The best of them would only form threads in soft materials with no visible cutting action. Miniature threads are best formed by cutting to reduce stress on the tap and reduce breakage. The cutting edge of a tooth can be sharpened by grinding if it is practical. However while possible it is not practical for the average homeshop machinist to grind threads that are only about .004" deep as in a 1.2mm tap. That is unless they have lucked on to some expensive specialized grinding equipment. Some very small taps will have thread depths down to .001" and smaller. Fortunately it is not necessary to grind threads on miniature taps if they are constructed properly. First a Tap blank is formed in a lathe. Then two right angle flutes are machined 180 degrees apart slightly deeper than the thread. Then and only then are the threads single point cut on the lathe. This leaves a sharp thread tip at the flute area that must be protected when hardening and tempering. Protection is accomplished by sealing the tap in a stainless steel container fitted for the Tap or Taps. In addition a small piece of newspaper is inserted with the Tap before the container is sealed. The paper burns when the container is heated removing oxygen and decreasing oxidation on the tap further protecting the sharp tips. A complete step by step procedure for this method is covered in the Jan.-Feb. 2008 issue of the Home Shop Machinist. The article also includes a sherline threading attachment modification to achieve up to 500 TPI. Jerry Kieffer ------- Re: Miniature Taps Posted by: "Willard E Wheaton Jr" wwheatonjrx~xxverizon.net Date: Sat Apr 26, 2008 3:29 pm ((PDT)) Thanks Jerry, I understand your procedure, and it makes sense to cut the flute relief prior to cutting the thread. Deburring could be done easily by stoneing prior to hardening. I also understand the need to prevent oxidation during hardening. For clock single tooth cutters, I have used a pipe nipple with pipe caps on each end to make a container, which in effect does what you described. I feel that the quenching is not as rapid, and had more success by wrapping layers of florist wire around the item, and coating with borax mixed with alchohol to form a paste. The alchohol evaporates rapidly, leaving a cocoon of borax surrounding the wire container. When heated the borax prevents oxidation, and quenching is rapid. Most of the borax falls off during the quench, or hot water will remove what remains. I'm sure you know this, just mentioning it for those that don't. We used to wrap tools in stainless foil, for oven hardening. With the foil package compacted around the tool, the quenching was rapid. If a small tap was placed inside a large container (relatively speaking), I wonder about the thermal effect of the dead deoxidized (air?) space surrounding the tap. However, it must work and I will see if I can get a copy of the HSM article. Should provide informative reading. Thanks for the education. Willard ------- Re: Miniature Taps Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Sat Apr 26, 2008 5:23 pm ((PDT)) Willard: With miniature taps because of the size, quenching has not proven a dependable or consistent method of hardening. With sizes sometimes as small as .010", the threaded part of the tap rapidly cools before it hits the liquid for Quenching. This is easily resolved by using A-2 drill Rod. Depending on the number of taps in a container and the size of the container, the container itself is sometimes quenched to assure hardening. I have not had oxidation problems with single point clock cutters since the only critical surface is dressed/sharpened on a oilstone. Jerry Kieffer ------- Re: Miniature Taps Posted by: "alenz2002" alenzx~xxbellsouth.net Date: Sat Apr 26, 2008 9:54 pm ((PDT)) Jerry, I don't know if you have tried this or not, but the watchmakers of old used beeswax to quench really tiny things such as pivot drills, etc. Hold the pin vise, (holding the drill) in one hand and the cake of beeswax in the other. Hold the drill over the alcohol lamp and as soon it shows cherry red (only seconds) quickly stab the drill into the cake of beeswax. Sort of like clapping your hands together more or less directly over the flame. Al Lenz P.S. And no, for the worry warts, I never ever heard of anyone stabbing their own hand with a red hot drill! ------- Re: Miniature Taps Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sun Apr 27, 2008 11:38 am ((PDT)) Hi. This trick is even easier to do if you use a candle: Heat the item in the candle flame, then plunge it straight through the flame and into the candle wax to quench. Ian ------- Re: Miniature Taps Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Sun Apr 27, 2008 1:21 pm ((PDT)) Al & Ian: Al, thanks for the suggestion on the use of wax for hardening. Many years ago when I started teaching myself watch repair I read about this method someplace. However personally I have had inconsistent results. I can only assume as with many old time watchmakers methods it is a acquired skill. These comments should of course NOT stop others from trying it. In the case of miniature Taps it does not address the issue of not allowing the flame to touch the sharp tips of the tap. Many times this will cause damage that is prevented with the fitted stainless container described. The stainless container is also an excellent and safe way of annealing a small watch arbor or part. After annealing, repairing and hardening a part using this method, the part will require very little polishing to return to original finish. Jerry Kieffer ------- Re: Miniature Taps Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sat Apr 26, 2008 5:08 pm ((PDT)) To prevent scaling, etc. I always used stainless steel wrap. We bought different size bags to suit the size of the work being heat treated. When the bag was removed from the oven at temperature, my trusty three corner machinist's scraper was used to stab the bag in a few places to ensure the quenching oil would penetrate the package. Then, the bag was immersed into the quenching tank. Worked well. Jerry G (Glickstein) ------- Re: Miniature Taps Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Sun Apr 27, 2008 1:42 pm ((PDT)) Mr. Glickstein: Since your comments were in response to my comments on miniature taps I would like to respond. Stainless wrap is a superb product for the larger parts it was designed for as you pointed out. However for the benefit of others who may try it on Miniature Taps or other small delicate parts per your post, it is not a good choice. It only offers limited oxidation protection and increases the chance of damage/breakage to tiny delicate parts such as miniature Taps. Jerry Kieffer ------- Re: Miniature Taps Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Sun Apr 27, 2008 5:12 pm ((PDT)) Mr. Kieffer, I must agree with your assessment. I was not advocating the SS wrap method for any delicate parts. When we had such parts to be heat treated, they were sent out to THE name in heat treating...Alfred Heller. I believe the company he founded in 1932 is still operating. No commercial connection. Mr. Glickstein P.S. As a side shoot of curiosity, what, in your esteemed knowledge would you classify "miniature taps" as? i.e., size, etc..... ------- Re: Miniature Taps Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Sun Apr 27, 2008 5:36 pm ((PDT)) Mr. Chieftoolmaker: I make taps and dies down to .009"x 354 tpi on a regular basis for use in model making. Anything below that is avoided if at all possible. Actually all Tap and die making is avoided if possible. Jerry Kieffer ------- [atlas_craftsman] Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "Paul DeLisle" ferretpdx~xxgmail.com Date: Tue Apr 29, 2008 8:39 pm ((PDT)) Okay....obviously, I have a *lot* more to learn than I thought. Two people have mentioned some kind of "wire" measurement....I'm completely lost. I've never heard of that measurement. I used a Thread Pitch gauge to confirm the 10TPI (and it fit perfectly, in pitch as well as depth.) Can someone explain the "wire" measuring? Thanks! Paul ------- Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "James Rice" james.ricex~xxgmail.com Date: Tue Apr 29, 2008 8:45 pm ((PDT)) http://www.vankeuren.com/tmo.aspx [for a complete explanation, and a useful site to bookmark] ------- Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Wed Apr 30, 2008 8:20 am ((PDT)) To properly measure the pitch diameter of a thread, you have to measure the sloping faces of the thread. The approved way is to lay "thread measuring wires" down in the thread and measure with a micrometer over the tops of the wires. Since the two sides of the thread are not opposite each other but interleaved, you use two wires on one side and one on the other to provide a stable set of surfaces for the mike to read from. Holding all this with your fingers is a real challenge, a couple of extra hands would be real welcome. Anyway, there is a chart that comes with the set that tells you what wire diameter to use for each range of thread pitches, and what you subtract from the reading to get the actual thread pitch diameter. The problem, of course, is this only works on external threads. So, for internal threads, if you don't have a sample to check on, you have to make a master first, using the thread wires and mike, so when you cut the inside threads you can check fit and keep cutting until the master is a snug fit in the thread. Did I explain it well? Probably not. Jon ------- Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Wed Apr 30, 2008 8:34 am ((PDT)) Actually, that was a pretty good description. What the thread wires are measuring is the pitch diameter of the threads. As long as there's a good fit between PDs the threads can be all sorts of messed up and they'll still feel like they're well matched. If 2 threads with the good PDs don't fit then the thread form has to be off. To hold the thread wires I've stuck the wire ends into foam (florist's worked pretty well until the wife caught me raiding her supply), packing peanuts worked OK, clay, whatever's handy. I've even put grease on the threads to hold the wires. Thread mics are easier to use than wires but are real finicky to get a good reading. ------- Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Wed Apr 30, 2008 6:54 pm ((PDT)) Robert Rochelle wrote: > I thought you explained it exceptionally well--especially the part > about extra hands. When I worked in QC I never could hold onto the > whole mess. Also had lots of small wire sets with only 2 wires left. Yeah, I almost mentioned that, I lost one of my wires already. They actually sell gizmos with 3 little o-rings and flexible wires to keep them from flying. I don't use them enough to need the gismo, or so I thought. Jon ------- Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "Pasek, Dennis Civ USAF AFMC 520 SMXS/MXDE" dennis.pasekx~xxhill.af.mil Date: Wed Apr 30, 2008 3:44 pm ((PDT)) I have used rubber bands to hold the larger size wires in place for 3-wire thread measurement. They can either be looped around the thread and over the wire or cut and pierced or tied to hold the wire. Initial positioning is a bit touchy, but once in place, the measurement is easy. I would think that a 3-ball method would work for larger female threads. the trick would be holding the balls. A plastic snap clip could hold the balls against extension accessories for the jaws of a caliper micrometer with just enough freedom of movement to do the job. Wire spring clips could also be made in a similar fashion. The limitations are that a separate pair of clips would be needed for each ball size, and tiny balls might not be suitable. Minimum ID would be limited by caliper jaw and ball dimensions. Similar clips for OD measurements could be made to hold wires retained by piercing bits of rubber. I posted a rough conceptual drawing in the 'dropbox': http://www.metalworking.com/dropbox/Thread_Measurement.jpg FWIW, Dennis ------- Re: Folks, I need help (*insert helpless, pitiful look*)... Posted by: "mf205i" mf205ix~xxyahoo.com Date: Wed Apr 30, 2008 5:08 pm ((PDT)) Two pieces of adhesive tape stuck together with two wires on one end and the single on the other. You will even be able to find them when you drop them in the chip tray. Mike ------- Tap Guide and Tapping Tips [LittleEngines] Posted by: "Ray and Ruby Brandes" rvbx~xxray-vin.com Date: Tue May 13, 2008 3:36 am ((PDT)) mini_engine wrote: > Ron, I have been thinking about making a tap guide or something to > help with the tapping process. I do all my tapping by hand. Gentlemen: The shop where I served my apprentiship had what we called a tapping block. I made one for myself and use it all the time. It is easily made and here is the description. Take a piece of 1" sq. mild steel about 5 or 6 inches long. Put it in the mill vise and fly cut one face. In the same setup drill, ream or bore holes to guide taps. My block boasts holes for #2 through 3/8". Case harden if you wish. To use it, put the flycut face against the work and put the tap through the proper hole. Holding the block tight against the work (don't clamp!) turn the tap in. 1. Unless you have a very short section to thread like sheet metal, try not to use more than 70% thread. I have uploaded a tap drill chart to the files section. 2. Cast iron should be tapped dry. Use no lube and clear the chips often, very often! 3. Spiral point plug taps (gun taps) seem to work the best. 4. Don't use big tap handles on small taps. 5. Use whatever you can to start the tap square to the hole. 6. Discard damaged or dull taps. A new tap costs a lot less than one broken in the work. One other thing to mention is thread forming taps. They require a bigger tap drill and the sizes are in Machinery's Handbook. These taps are great for blind holes that need to be tapped all the way down. Thread formers don't generate any chips. The resulting thread is less than with a cutting tap, but if you have 2x diameter engagement there shouldn't be a stripping problem. Regards, Ray in FLA ------- Re: Tap Guide and Tapping Tips Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Tue May 13, 2008 10:39 am ((PDT)) Hi Ray, I use a similar idea to keep taps true when tapping. I make small guides out of large bolts. See here for the pics: http://s219.photobucket.com/albums/cc210/ian-new/5%20-%20tapping%20guide/ Ian ------- Re: Tap Guide and Tapping Tips Posted by: "Ray and Ruby Brandes" rvbx~xxray-vin.com Date: Tue May 13, 2008 2:48 pm ((PDT)) Ian: That's the idea. I never thought to make individual ones, but if I couldn't get 1x1 CRS that hex head screw is fine. I'll bet you make 'em in the lathe, no? Regards, Ray in FLA ------- Re: Tap Guide and Tapping Tips Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Wed May 14, 2008 7:12 am ((PDT)) DA Dossin wrote: > Ian, I think you showed those before. When I saw them... I immediately > made a set for the taps I use. Thanks... they work well Hi Dan, Ray. Thanks, it is not often I get to say something clever -- I like to make the most of it! It is not my idea. When I started in engineering many years ago I worked for four years next to a very old and wise toolmaker. He had a beautifully turned set of tap guides, carefully polished, delicately knurled (and probably case-hardened too) fitted into a lovely wooden box. I thought it was such a simple, clever idea that I just had to copy it. His tap guides were works of art - mine are the bargain-basement version. As Ray pointed out - these are so simple and quick to make on the lathe that I have one for each of the small tap sizes I use and I keep them with the appropriate tapping and clearance drill for each size. It also helps if you stamp the tap size on the flat of the bolt -- makes life easier when you have several on the bench at the same time. Ian ------- cutting camera lens threads? [MyMyford] Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Wed Jun 4, 2008 3:17 pm ((PDT)) Hi group. I haven't used my Myford 7 much since I got it, but now I am faced with a need to cut fine threads on aluminum tubing for a special lens addition on my camera. Has anyone ever done this? Does anyone know how many threads per inch on camera lenses? How do I set up my lathe to do such fine work? Sorry to sound so helpless, but I need to learn this art quickly, and I appeal to all for your wise advice. Kind regards, Larry Heyda -------- Re: cutting camera lens threads? Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Wed Jun 4, 2008 5:07 pm ((PDT)) A plethora of different threads are used on camera stuff. For example, Leica screw is M39x26tpi, C-mount is 1"x32tpi, a Compur 00 shutter is m25x0.5. What are you planning to mount? ------- Re: cutting camera lens threads? Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Wed Jun 4, 2008 5:49 pm ((PDT)) Hi Ken, Good to hear from you again. I found out I need to cut the standard thread that is on most filters for lenses on the new DSLR's-- .75mm. That will work for me. I've just been reading a good little book called "The Amateur's Workshop" to learn how to set my lathe for these tiny threads. I think I got a thread cutting attachment with the lathe, but I haven't had a chance to look for it yet. Then, I guess I have to figure out how to use the change gears. Fun! Well, I better learn it sometime. Larry ------- Re: cutting camera lens threads? Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Wed Jun 4, 2008 6:10 pm ((PDT)) Did your lathe come with a gearbox? Did you get the metric conversion setup (Myford part #1481) which is required for exact metric threads? This option consists of an alternate banjo (gear quadrant in Myford speak) plus a number of gears (28T, 35T, 30T, 44T, 2x45T, 2x50T, 2x60T and 63T). However, there are some combinations of the standard gears that get you very close to 0.75mm. For something like a filter adapter with only a few threads I suspect that they are more than good enough. Perhaps someone else can provide the best gear combination for your job. ------- Re: cutting camera lens threads? Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Wed Jun 4, 2008 7:27 pm ((PDT)) Hi Ken, Yes, my lathe has a gear box and a bunch of change gears. I looked in the Super 7 manual, and it lists the gears needed to cut metric threads. For a75mm I have all the gears necessary except for one-- a 21 tooth. So I guess I'll have to order it from Myford or somebody else. Thanks again for your help. Larry ------- Re: cutting camera lens threads? Posted by: "tr0up" a.troupx~xxemail.com Date: Wed Jun 4, 2008 6:49 pm ((PDT)) The main trick to cutting threads of only a few turns is to improvise a handle for the left hand end of the spindle (at a pinch, and thumbing your nose to OSH, on a Super 7: remove the changegear cover and clamp the 4-jaw chuck onto the spindle end - on an ML7, remove the primary belt cover from the motor to the [top] countershaft and pull the big pulley round by hand, with the 3-speed belt on top speed) If your lathe has a clutch this can be used instead, but when starting out a handwheel or pulley is much more instinctive. You'll want a good light source and a lens for inspecting progress. For tiny threads I wouldn't bother with the complication of setting the topslide at a flank angle of half the thread angle, as most texts recommend. Just leave it parallel to the leadscrew and move it leftwards by 0.001" every couple of cuts. Put a pencil mark on the cross slide index to tell you when you're theoretically at full depth. You'll actually need to cut deeper than this (mainly due to the tool being sharp, whereas the theoretical depth is to a radiused root) but do this by trial and error, deepening by 0.001" at a time, and trying a female thread on after each cut. Ease the entry before trying the fit, on these big diameter threads, by coming up to the start of the thread a few thou deeper, and retracting back to correct depth within 20 or 30 degrees of rotation (sort of like a helical on-ramp) Someone else will be along soon to tell you some geartrains you can use to approximate to 0.75mm. I fully agree with Ken that a fair approximation will be perfectly adequate because the thread is so short, and in any case there is virtually no load. ------- Re: cutting camera lens threads? Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Wed Jun 4, 2008 7:29 pm ((PDT)) Hi TrOup, Sure appreciate your help. A lot of good tips in your email. As I just wrote to Ken, I only lack one gear inorder to cut the .75mm thread. Once I get that, I'll follow your directions and see what happens! Larry ------- Re: cutting camera lens threads? Posted by: "DA. Forsyth" notLeftBehindx~xxiwr.ru.ac.za Date: Wed Jun 4, 2008 11:44 pm ((PDT)) > Has anyone ever done this? yes, I made a 52-55mm adapter for lens filters > Does anyone know how many threads per inch on camera lenses? Filter threads are 0.75mm pitch iirc. If you mean the other end, lens to body, the pentax stuff is on the web, just search. Best is to cut to fit though, which is what I did... > How do I set up my lathe to do such fine work? I used a sharp handground tool made from a round file. one end was for outside threads and the other end I heated and bent over for the inside threads. You need a spindle crank because with a metric pitch you cannot ever disengage the halfnuts once you start cutting the threads. you have to wind the spindle backwards after making the cut. (My lathe does not have reverse, and will never have it, since the chuck can spin off in reverse.) > Sorry to sound so helpless, but I need to learn this art quickly, and > I appeal to all for your wise advice. Now look at http://iwr.ru.ac.za/~iwdf/lathe/crank.html for the spindle crank and http://iwr.ru.ac.za/~iwdf/lathe/ring.html for the adapter ring I made Easy enough, just takes a bit of planning, and then a bit of patience and focus. Don't forget the kerosene as cutting lube on the aluminum for a nice finish. You're running the tool very slow, much slower than normal cutting speed, so surface finish suffers. Though i did find I could turn the handle pretty fast for a turn and half which is how long my threads were. (ps, anyone know the pitch on the internal 39.5mm dia body threads on a Kodak DX7440?) David http://iwr.ru.ac.za/~iwdf/ ------- Re: cutting camera lens threads? Posted by: "durnfjmx~xxaol.com" durnfjmx~xxaol.com Date: Thu Jun 5, 2008 12:55 am ((PDT)) If this is a first or early attempt at thread cutting, I think I would practice on some more "usual" and non-critical threads first. I made an adaptor ring some years ago in order to fit a smaller filter to a lens. As it was to be a 1-off use, I simply made a plain plastic (polyethylene at a guess) ring which was a very light push fit on the threads - very quick and easy, and actually lasted for years of occasional use. MikeD ------- Re: camera lens threads? (DA) [MyMyford] Posted by: "DA. Forsyth" notLeftBehindx~xxiwr.ru.ac.za Date: Thu Jun 5, 2008 8:10 am ((PDT)) On 5 Jun 2008 at 8:41, Larry Heyda murmured decisively: > Dear DA, > Thanks for this super information.. Wow, plans for the crank and > everything. My only doubt is that maybe I read the Myford manual > wrong where it lists the change gears needed. From what I'm reading > on these posts, it sounds like the right combination of gears to > produce the ..75mm thread is not so easy to come by. DidI read the > manual wrong? On page 103 of the Myford series 7 manual it lists > METRIC PITCHES. I go down the column titled FEED PER REV. to .75 and > then go across, noting the 45 DRIVER, 40 DRIVEN, 35 DRIVER 50 DRIVEN, > 21 DRIVER (I need this one), and 70 LEADSCREW. Can someone confirm > that this is what I need? Forget the manual, they just list convenient setups and include gears they sell as expensive extras. I don't have a 21 and I cut this thread. How? By using a program to calculate the gears I can use from the set I *have* got. You can do it too. Click 'here' on this page http://iwr.ru.ac.za/~iwdf/lathe/change.html and follow the instructions. You will need to edit change.dat to list the gears you DO have (I have the unusual 12 and 95 gears). (NB: this is not a point and click program, you actually have to type a command in a DOS window.) so you'll want something like change /m 0.75 which gives me 2 sets of possible gears 3.944 :: Drivers 20 38 50 Driven 45 55 65 ratio 0.236208 error 0.005180% 3.044 :: Drivers 25 38 40 Driven 45 55 65 ratio 0.236208 error 0.005180% They'll both fit the banjo, but it will take some fiddling around. Just make sure that the ones listed under 'drivers' drive any one of the ones listed as driven and it will be fine. And then put some scrap in the chuck and turn a 'scratch' on it and compare that to the camera/ruler/vernier caliper etc. Ten turns should be 7.5mm long. Easy. Now I must go and mow the lawn.... David http://iwr.ru.ac.za/~iwdf/ ------- Re: cutting camera lens threads? Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Thu Jun 5, 2008 1:23 am ((PDT)) Hi Larry, The best way to produce fine threads on large diameters is to mill the thread - this is the process usually used comercially. Instead of a single point tool in the tool holder, imagine a small motor mounted on the lathe cross slide driving a little side and face cutter ground to the thread profile. The cutter has to be angled to match the lead of the thread. The lathe carriage is set up to feed as the work rotates in the usual way (as per the change wheel calculations you already have). The work rotates in the lathe at a relatively slow rate (say 10 rpm). The milling cutter turns at high speed and cuts a full depth thread in a single pass. For home use it quite straightforward to make a simple milling cutter to do this job. I use a piece of silver steel (drill rod) and grind back a little neck near the end so you are left with a small disk at the end of the rod. If you can grind a thread profile on a single point tool you will have no problems grinding the same profile on the periphery of the disk at the end of the rod. I use a fine grinding point on a Dremel type tool to cut the disk to provide two cutting teeth - a more conscientious person would do this in a T&C grinder or a milling machine to ensure the cutting angles are correct. Heat treat, hone, and there you have it. Mount the home-made cutter in a drilling spindle set to the appropriate angle in the tool post. If you are cutting Al. you sould have no problems with a home made cutter. Ian ------- Re: cutting camera lens threads? Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Thu Jun 5, 2008 3:54 am ((PDT)) Even easier than that to make one from a tap of the right thread pitch - simply grind off all bar [except] one of the flutes. Regards, Tony ------- Re: camera lens threads? (Tony) [MyMyford, with subject line changed] Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Thu Jun 5, 2008 7:51 am ((PDT)) Hi Tony, I like the idea, but a problem with using a ground down tap is that the tap would need to be mounted with its point towards the tailstock to ensure the cutting edge of the tap was pointing upwards. This would make powering the cutter tricky. It would also make the angle setting a little harder as the lead on the tap would need to be taken into consideration (and would be 'the wrong way' - i.e. suitable for milling a left-hand thread). Ian ------- Re: camera lens threads? (Tony) Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Thu Jun 5, 2008 8:31 am ((PDT)) Hi Ian - You have a number of degrees of freedom to play with here, so perm any N from the following and I'm sure that you could find a workable combination. 1) Use a left hand tap if that makes life easier for you. 2) Form a cutting edge on the other side of the flute (not hard to do) if need be. 3) Mount the cutter spindle in the "rear toolpost" position, or even directly above the work, if that makes setting the angle easier. 4) You could grind away the "back" (non-cutting edge) of the tap flute so that the tooth was narrow enough that you didn't care about the helix angle of the tap at all; the tooth wouldn't be as strong, but as the OP [Original Poster] is planning to cut aluminium, this would probably work just fine. By the same token, the diameter of the thread he is cutting is very large relative to the thread pitch, so you could probably get away with ignoring the helix angle of the thread as well. I will grant you it might involve a spot of thought & imagination, but the point (pun intended) is that it gives you the right thread form with minimal effort. Regards, Tony ------- Re: cutting camera lens threads? Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Thu Jun 5, 2008 3:51 am ((PDT)) Of course the other way to get good threads is to buy them ready made - for example, the square filter systems (Cokin etc) use adapters that are basically a metal flange with a suitable diameter male filter thread on one side; similarly, you can buy ready made step rings with various combinations of male and female threads. Wouldn't be hard to attach something like that to the end of the tube. I have made lens reversing adapters that way with considerable success. SRB carry a good range of such rings and will also machine to order if you need them to: http://www.srbfilm.co.uk/ Regards, Tony ------- Re: camera lens threads? (Tony) Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca Date: Thu Jun 5, 2008 8:49 am ((PDT)) If the tap is rotating much faster than the spindle does it really matter if the tap is cutting up or down? This would seem to be the same as climb milling which often gives a better finish than conventional milling. ------- Re: camera lens threads? (Tony) Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Thu Jun 5, 2008 10:49 am ((PDT)) Absolutely. Regards, Tony ------- Re: camera lens threads? (Tony) Posted by: "tr0up" a.troupx~xxemail.com Date: Thu Jun 5, 2008 2:09 pm ((PDT)) First let me say I think we're using a baseball to squash a mosquito here: given that the material is alu alloy (as long as it's a reasonably hard temper, ideally T6) a single point tool will do just fine. Personally I think suggesting thread milling to a guy who hasn't done screwcutting is not ideal, as the amount of information he's now being presented with testifies. However, I'm happy to add to the pile of that information, in the name of progress and general enlightenment, and failing that, entertainment at my degree of ignorance.... > >If the tap is rotating much faster than the spindle does it really matter if the tap is cutting up or down? This would seem to be the same as climb milling which often gives a better finish than conventional milling. < < I concur, but that resolves one of the two problems which have already been raised. The other remains, that of 'helix angle' handedness. When milling a thread, the relief on the cutter needs to be to the opposite hand to the thread. Ideally, as stated, you'd use a LH tap for milling a RH thread. This might be 'trumped' if the form relief on the tap exceeds the discrepancy, and this would be more likely if the tap used for a milling cutter was large (making the helix angle small). Good luck finding such a tap, though: it's likely to be as hard or harder than finding a LH tap, which for this pitch is effectively nil (see below). Which brings me to my final point: the nearest thing to a standard tap you will find for that pitch is ISO coarse M4.5 or ISO fine M6. Frankly I doubt there's more than a handful of outlets for either of these in the entire continental US so the question's largely academic, but these are just too small to make satisfactory milling cutters for anyone not highly skilled in the art, to my mind. However if you can find an SI DIN fine M8, you'd be (comparatively speaking) cooking with gas ! Good luck, if you choose this route .... ------- Re: camera lens threads? (Tony) Posted by: "tr0up" a.troupx~xxemail.com Date: Thu Jun 5, 2008 2:24 pm ((PDT)) Larry: I think there's a number of things here which risk clouding things for you, always a risk on these forums - the more helpful and inventive people are, the more diverse the range of suggestions. I infer that you have a Super 7 with an imperial leadscrew (8TPI) and a quick-change gearbox. Please correct me if I have this wrong. If so, you need to ignore the part of the manual you've quoted, which relates to lathes whose screwcutting relies on trains of changewheels or changegears. Rich Dean's advice points the correct route for you - you need to get the correct gears for the short train between the tumbler reverse and the input to the gearbox. I can't help much here, unlike Rich, I don't have such a gearbox, and don't know the ins and outs of the translation gears required. Unfortunately, the vast range of approximations such as those suggested by DA Forsyth are not available to those using a QC gearbox - It's a tradeoff between convenience and comprehensiveness. It's said there are as many as 750,000 different pitches theoretically available using the standard set of changegears. (Martin Cleeves - Screwcutting in the Lathe) Lastly, the supposition in my last post that you were somewhere in the USA was egregious, based solely on your name and the spelling of aluminum - I hope you're not Canadian, or an expat, or (most likely) that my evidence was not just too flimsy ! ------- Re: camera lens threads? attempting.... [MyMyford] Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Thu Jun 5, 2008 3:03 pm ((PDT)) Dear TrOup, Yes, I DO live in the US, and I do have a Myford 7, but no quick change gear box. After hearing all the excellent suggestions, I've decided to try my own silly way to do these threads. It's a bit hard to explain, so I'll see if I can actually pull it off before I report to this intelligent forum again. But I'm going to try to use two engaged filter threads as the driver to move along my Foredom handpiece with a Dremel saw bit in it that has been ground to make pointed teeth. The Foredom slides alongside the extended barrel of the tailstock, running parallel to it, and just the right distance away to cut 62mm threads on my aluminum stock clamped in the chuck. One of the filters is soildly joined to the Foredom, while the other is joined solidly to the stock. As the chuck is turned, it pulls the other filter toward it, and my threads are cut (hopefully!). ------- Re: camera lens threads? attempting.... Posted by: "tr0up" a.troupx~xxemail.com Date: Thu Jun 5, 2008 5:59 pm ((PDT)) Larry Not a silly idea at all, sounds like you have reinvented thread chasing, which has been much used, and in fact incorporated on some very high precision lathes and thread grinders. Often the "master" thread was coupled at the left end of the main spindle, and a rod connected a tracer (effectively a cut-down half nut, maybe a "tenth nut" to the carriage) Your implementation sounds most ingenious. I presume the 'master thread' is a bit longer than the slave you need it to cut? Provided the Foredom doesn't have too much end float (per another poster), it definitely sounds to be worth a try. If it does, you might find you can dismantle it and add one or more shim washers to apply a slight preload to one of the outer bearing raceways. I did this with a flexible cable-driven industrial Dremel, to be able to use if for toolpost grinding. I cut the washer from heavy brown paper, using a sharpened pair of dividers as a cutting device. With grinding, end float is even more critical than with milling. Apologies for muddying the QC gearbox waters - I got the wrong idea somewhere. Is yours an ML7 ( three speeds on the cone pulley in the headstock) or Super 7 (four speeds " " " ")? In either case, I highly recommend getting a 21T gear in due course if you're likely to do much metric threading: that's the only additional gear you need, and means you can simply use the manufacturer's proven geartrain solutions for all metric pitches. They're still approximations, but the error is negligible unless you're making micrometers. The problem with using calculated solutions is that sometimes they don't fit together on the banjo, which can cause a bit of mucking around if you have to try several solutions, given that you really need to clean the toothspaces of all gears before fitting them up, if you want them to last. (Of course if you're the disciplined type, you'd clean them after the job, before putting them away, and this would be less of an issue...) ------- Re: camera lens threads? attempting.... Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Thu Jun 5, 2008 9:41 pm ((PDT)) Hi TrOup. Thank you for the encouraging words. I know this isn't the very best way to do this, but I don't need complete perfection for what I'm doing. The biggest problem I'll have is that I can't find a 62mm thread longer than the standard filter length, which is not much more than 2 1/2 threads. So I don't have much room to play around, but I'll give it a try anyway. The Foredom doesn't seem to have any end play. I chucked a thin cut-off disk in it and buzzed into a piece of steel. When I turned it off it fit tightly in the little groove. So I think it'll be good enough. Just wish I had a longer thread. This is a better solution than using change gears because, I need to make many of these threaded lips, and I need to use the lathe at the regular speed as I make each one. They go on a stereoscopic camera attachment I'm putting on the market next month. I'm cutting them out of a long thick tube of aluminum with a 2 1/4" i.d. and a 3" o.d. I'll make the tube master thread just hug the tube, and be able to slide along it and clamp, so that I can cut the lip, thread it, cut it off and start another, thread, cut it off, etc. I'll send a picture to the forum if it works. The 62mm thread is all I need so I'm setting it all up for that size only. Larry ------- Re: camera lens threads? attempting.... Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Fri Jun 6, 2008 12:29 am ((PDT)) Can I suggest a refinement? Rather than using two engaged filter threads to do the driving, why not use a length of Metric studding of the right pitch (M5 for example), and a matching nut? That way, you are not limited to the 2.5 turns of engagement that you get with a standard filter. You also have some potentially neat solutions then for attaching the screw to the spindle - for example, get a MT2 blank arbor, drill/tap it axially to take the studding, and fit a drawbar at the back to secure it in the spindle. This shouldn't interfere with your using a 3- or 4-jaw chuck at the same time to hold the tube. Also, I suspect that you might find it more convenient to mount the Foredom on the cross-slide rather than using the tailstock, but YMMV. Regards, Tony ------- Re: camera lens threads? (Tony) Posted by: "DA. Forsyth" notLeftBehindx~xxiwr.ru.ac.za Date: Thu Jun 5, 2008 11:46 pm ((PDT)) On 5 Jun 2008 at 21:24, tr0up murmured decisively: > Unfortunately, the vast range of approximations such as those suggested > by DA Forsyth are not available to those using a QC gearbox - It's a > tradeoff between convenience and comprehensiveness. Fortunately, the software I used has been superceded by Marvin Klotz' new version which allows for a changegear train AND a gearbox. Takes longer to run, but it will find a combination if at all possible, within setable limits of accuracy. David http://iwr.ru.ac.za/~iwdf/ ------- Re: camera lens threads? (Tony) Posted by: "duncanwebster" duncan.webster2x~xxntlworld.com Date: Fri Jun 6, 2008 3:07 am ((PDT)) I must agree that this is all getting far too complicated. Cutting a fine pitch thread with a single point tool is not difficult, and is much easier than all these esoteric solutions involving taps and dremels. You can't turn the topslide to feed down the thread flank with a ML7, but since being told the following (by a guy who worked in shipyards just after the 1st world war) I never bother doing that anyway. With the topslide parallel to the spindle advance the tool till it just touches the job. If you have a zero setting index ring (very useful, can be backfitted to ML7), set it to zero, and set the topslide to zero. If not, set the topslide to half the reading on the cross slide. Move saddle towards the tailstock clear of the job and advance the cross slide by 10 thou. Also advance the topslide by half of this, ie 5 thou. Drop in the clasp nuts and cut the first Pass. I would do this in backgear, but if it's your first go, do it by pulling on the belts. When you reach the leftmost end, wind the cross slide back at the same time as releasing the clasp nut. Return to start point, and advance the cross slide by another 5 thou, and the topslide by 2.5 thou (no need for extreme accuracy) and cut again. repeat till you get close to the depth needed, and then go in smaller steps till it fits. Moving the topslide means that the tool is effectively following the thread form and is only cutting on the leading edge. Thus the swarf can get out of the cut easily, and it all works much better than plunging it straight in. For aluminium, grind plenty of top rake (remember its only cutting on one edge) or you will suffer from the dreaded 'built up edge'. Use of cutting lubricant helps as well. Some people use paraffin (kerosene), but I use tapping compound for a slow speed job like this. You are not trying to get rid of heat, just stop the swarf sticking to the tool. Setting topslide to half cross slide at the start means it stays half the cross slide and makes it easy to remember where you are up to. Can you set up to cut 34 tpi? If so you will find it very very close to 0.75mm pitch, less than 0.3% difference. Over a short length it probably doesn't matter. If you can tolerate a short undercut at the headstock end, it all gets even easier, as the tool cuts into fresh air and all you need do is release the clasp nut at approximately the right time. I invariably adopt this when cutting internal threads as you can't see what is going on. Whilst on the topic of internal threads, try putting the tool in upside down and cutting on the far side. Then the motions are the same as external and you don't get confused as easily. Plus the chipping fall clear of the tool more readily ------- Re: camera lens threads? (Tony) Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Fri Jun 6, 2008 4:51 am ((PDT)) Hi Tony, Please forgive my ignorance, but what does the word "studding" mean? Is it an English term for threaded rod? I suspect it is. I love your idea, but I couldn't find any threaded rod with a .75mm thread. I assume M5 refers to a metric thread size, so I'll search in that direction. I bet I sound VERY ignorant. I'm not a machinist per se -- I'm a sculptor with a Myford lathe, so you have to be a little forgiving with the likes of me. It's a great idea. Larry ------- Re: camera lens threads? (Tony) Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Fri Jun 6, 2008 5:13 am ((PDT)) Hi Tony, I just went to buy M5 studding and found out it has an .8 pitch. Is this really close enough to .75 for my needs? It sounds OK as I'm only using 2 or 3 threads for my ring, but I thought I'd make sure with you.... Larry ------- Re: camera lens threads? (Tony) Posted by: "DA. Forsyth" notLeftBehindx~xxiwr.ru.ac.za Date: Fri Jun 6, 2008 6:33 am ((PDT)) > I just went to buy M5 studding and found out it has an .8 pitch. Is > this really close enough to .75 for my needs? It sounds OK as I'm > only using 2 or 3 threads for my ring, but I thought I'd make sure > with you.... IMHO, not close enough. With that much difference you have a high risk of pulling threads out. Since only a small portion of the thread is in contact (instead of the 3 full turns normally required) it easily overloads that small portion, progressively pulling the thread out with little effort. I've had this a couple of times when mixing M6 and 1/4"BSF David http://iwr.ru.ac.za/~iwdf/ ------- Re: camera lens threads? (Tony) Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Fri Jun 6, 2008 5:24 am ((PDT)) Hi Larry - My apologies - yes, you're right - M5 is 0.8 pitch. M4.5 is 0.75 pitch, and probably difficult to find. The difference is about 6 or 7% - might be pushing your luck. Regards, Tony ------- Re: camera lens threads? (Tony) Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Fri Jun 6, 2008 5:57 am ((PDT)) Hi Tony, Well, I found some M4.5 tapping screws on this site. I guess I'll try those. The only other resource was to buy a M4.5 tap and an M4.5 die. Mmmm, I guess I'd only need the tap, because I could USE it to tap a hole. DUH! Larry ------- Camera filter threads cut! [MyMyford] Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Mon Jun 30, 2008 5:36 am ((PDT)) I'm happy to say that I was finally able to cut .75 metric flter threads on my aluminum adapter pieces for my stereo camera. The setup allows me to machine the adapter, cut the threads, cut off the adapter, move over and cut a new one, thread, etc., without changing any gearing. I did four pieces in about 90 minutes. To tell the truth I was a little amazed when a stock filter just screwed on this thing as sweet as anything after I'd cut the first thread. Praise the Lord! I've posted 4 photos in the file section. [Unfortunately the MyMyford group and its files are long gone.] The cutter is a Dremel bit that I ground into a V edge with another Dremel loaded with a cut-off wheel. I cast urethane resin around the tailstock mandrel and Foredom handpiece first. Before doing so, I wrapped the Foredom in tape and smothered it with Vaseline. The tailstock mandrel was also well greased. Then I put them in a cut- off plastic empty baby powder container, made them parallel, and poured in the quick-setting resin. Afterwards, I cut the casting down the middle, and screwed the two halves together with a bit of material in between to give a rocking situation. This allowed me to get very fine adjustment on the depth of cut. A piece of 1/2" threaded rod goes through the headstock mandrel, and is clamped tight by nuts at each end. The .75 metric threaded rod is brazed to the 1/2" rod and goes into a threaded hole in a plate attached to the urethane block. Thank you for all your advice. Larry Heyda ------- Re: Camera filter threads cut! Posted by: "tr0up" a.troupx~xxemail.com Date: Mon Jun 30, 2008 7:31 pm ((PDT)) Larry I can only imagine how satisfied you must feel to have developed a solution which is possibly one-of-a-kind, and which does exactly what you want with the resources at your command. Were you able to do the entire depth in one cut? To my mind, that would be one of the main benefits of your milling solution over a turning solution, the other being the ease of finishing such a short thread - at the desired rotational phase - without the need for a runout groove or any panicked winding out of the cross feed. Thanks for sharing the satisfaction, which we can enjoy a small portion of, by proxy... Respect ! ------- Re: Camera filter threads cut! Posted by: "Larry Heyda" larryedax~xxembarqmail.com Date: Mon Jun 30, 2008 10:29 pm ((PDT)) Hi TrOup, I really had no idea if it would work at all. The Foredom is quite old, and the cable rattles inside the housing. But I turned the tube down to what seemed like the right diameter, put the Foredom cutter next to the edge at what seemed like the right depth, turned it on, and started rotating the chuck into the cutter. It went very easily, and before I knew it I was four threads in. Then I kept ithe Foredom running and unwound the chuck, and backed off the cutter. I picked up a filter and it just screwed on as if it was a Nikon lens! I couldn't believe it. Just the right amount of play and everything. But the further fun was that I could repeat this after each time I turned more of the pipe, because the cutter stayed in exactly the same position in relation to the diameter. Thanks for your email. I was thinking my announcement was so full of pride that nobody would want to respond to it. I was just a very happy guy, and wanted to share. Larry ------- Re: Tapping [sherline] Posted by: "Alan Haisley" alanhyx~xxroadrunner.com Date: Tue Sep 16, 2008 5:33 pm ((PDT)) "mkaman69" wrote: > I need to tap the end of a .43 inch diameter by .53 long piece of > brass rod to #0-80. I have the end drilled to .3 deep. > I've been holding the tap in my right hand and a tapping guide block > and the part in my left. Even though it's awkward, it works. > Is there any other method I could use? > I'm going to end up tapping around 4 dozen pieces like this for a > project I'm doing. Will post photos after I get the prototype cleaned > up. Michael Michael: If you hold the rod in a lathe chuck, put the tap in a Jacobs chuck in the tailstock, and release the lock on the tailstock; you can turn the lathe by hand while applying enough pressure on the tailstock to get the thread to start. It will then self feed and you can rotate the spindle chuck by hand either forward or backward to clear the threads. Even if you back it clear out you will be able to get it to restart as needed. Since this is a blind hole you may want to back out and clear the hole with compressed air a few times as you go. You may want to hold the Jacobs chuck when backing out to keep it tight on its arbor. Alan ------- Re: Tapping Posted by: "mileagemayvary" gizmomakerx~xxbigpond.com Date: Tue Sep 16, 2008 10:51 pm ((PDT)) TOOL TIP: When tapping a blind hole, one can become extremely nervous. Is the tap just tight, or is it at the bottom, and the next turn you make will break the only tap you have and destroy the part and the time you have in it. Then, after 60 years of tapping and breaking, the solution became just so obvious or maybe I have a repressed memory from seeing it somewhere. Especially applicable for tapping several parts. 1. Thread two nuts onto the tap. 2. Poke a piece of wire into the blind hole and measure its length. 3. Thread the two nuts along the tap for this length MINUS about 1mm and lock them together. 4. Keep backing out the tap and clearing debris from the hole bottom. 5. Tap away worry-free because you can see when you are fully threaded, and the nut/locknut will prevent you from bottoming. I always do this now and have never broken a tap since :) Rob ------- Re: Tapping Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Wed Sep 17, 2008 7:57 am ((PDT)) A few more suggestions: In blind holes use spiral flute taps (search in McMaster.com for details). They channel the chips up out of the hole. If you have some sort of depth stop on the tap, this can block the chips from coming out; I just count the turns. Tap guides that don't provide clearance for chip extraction can also be a problem. A guide also needs to have a broad enough base to ensure the tap is normal to the surface of the work, and to avoid side loads. See my photo at http://tech.ph.groups.yahoo.com/group/sherline/photos/view/d71e?b=1 for a well designed tapping guide. If there is any doubt about whether you're going to successfully tap a hole, take the time to try a few tests on some scraps of the same material before you risk a workpiece you've got a lot of time in. You may find you need a new tap, or a slightly larger hole. DC ------- Re: Tapping Posted by: "David Morrow" morrow2002x~xxlightspeed.ca Date: Wed Sep 17, 2008 2:38 pm ((PDT)) On blind holes, I pull the tap out often and clean out the hole with compressed air. Then, I take a dental pick or something similar depending on how deep the hole is, and get it right to the bottom and slide it up the side. It doesn't take much to figure out how close the first groove is to the bottom. On shallower holes, I start with a bright light and maybe a magnifying glass. If necessary, I keep running the tap one turn at a time; less if I'm really close. I have some taps that are meant for blind holes - no taper. I change over to these taps half way through the process. On non-blind holes, I pull the tap when I feels that things are getting bound up. I'm more concerned that the chips will cause more problems than the possibility of cross threading. BTW, I typically use WD-40 as a threading lubricant. I've never heard of anyone else doing this but it's my preferred lube. ------- 55 Degree thread cutting [MyMyford] Posted by: "zitman2008" imarshallx~xxrocketmail.com Date: Wed Sep 17, 2008 4:21 am ((PDT)) Hi all, Can anyone tell me where I can get a 55 degree external threading tool. I can find 60 degree ones but I need to cut whitworth threads. I am not competant, at the moment, to grind my own! Thanks Ian ------- Re: 55 Degree thread cutting Posted by: "mike.crossfield" mike.crossfieldx~xxvirgin.net Date: Wed Sep 17, 2008 6:19 am ((PDT)) Lots of suppliers out there. One example is Chronos. Try www.chronos.ltd.uk/ Enjoy Mike ------- Re: 55 Degree thread cutting Posted by: "DA. Forsyth" notLeftBehindx~xxiwr.ru.ac.za Date: Wed Sep 17, 2008 7:02 am ((PDT)) > I am not competant, at the moment, to grind my own! Nor was I, till i tried. I grabbed the biggest whitworth bolt I could find and compared my tooltip to that as I ground it by hand. Turned out to be easy. David http://iwr.ru.ac.za/~iwdf/ ------- 55 Degree thread cutting Posted by: "duncanwebster" duncan.webster2x~xxntlworld.com Date: Wed Sep 17, 2008 1:00 pm ((PDT)) You can get a thread tool grinding gauge which is about 2 by 1.25" with notches cut in to act as a guide when grinding and a useful setting aid to get the tool square to the job. I've had mine since I helped Noah with his ark, so no idea where you get them from now, but a decent engineers merchant should have them. Mine is stamped up 'Moore and Wright No 200' You really should tackle grinding tools by hand, using a carbide insert for threading on our small lathes is overkill. I use carbide for heavy metal shifting, but do a lot of turning with 1/4" square bits. Get some 1/4 square mild steel to practice on, a good bright light over the grinder, and a jeweller's eye glass (about 4 * magnification is enough) to see what you've done. Rake angles aren't all that critical, and centre height doesn't need to be that accurate as long as you're not working on very small stuff. In the dim past when I drove a lathe for a living, the thinnest packing we had for the 4 tool turrets was 1/16 thick. What is important is enough clearance both front and side, small radius or flat at the very end, and a good sharp edge, although finish off the grinder is good enough for most jobs. I do have one of those Australian tangent tool holders. Very good, but they result in a lot of overhang, so not much use for heavy cuts, and they are quite expensive, especially when the good old post office try to charge you import duty, with a Ł20 handling charge on top. I can't find any reference to DIY ones, if anyone has a link please post ------- 55 Degree thread cutting Posted by: "zitman2008" imarshallx~xxrocketmail.com Date: Wed Sep 17, 2008 3:08 pm ((PDT)) Thanks Duncan, I have got one of the thread gauge thingys you describe, it just never struck me to use it!!! I have ground 1 tool for a particular project which I had no idea how to do with the tooling I had and I did buy some HSS tool steel blanks a couple of weeks ago so perhaps I should get my finger out and give it a go. Years ago in a past (working) life I was very good at grinding parting off blades so perhaps it will all come flooding back. Ta Ian ------- Re: 55 Degree thread cutting Posted by: "Christopher Hicks" cmh21x~xxcam.ac.uk Date: Thu Sep 18, 2008 12:44 am ((PDT)) You can also use a threading gauge (you know the little razor-blade sized piece of metal you use to help set a threading tool perpendicular to the work) as a grinding gauge to get the angle on the tool right. If you already have a 60 degree tool that you don't need then the amount of grinding needed to transform that into a 55 degree tool is pretty small. Unless your thread is super-critical I would also suggest just having a go. I managed to make a perfectly serviceable Myford nose thread at my first attempt, with a 60 degree tool modified to 55 degree. Christopher ------- Threading Question [mlathemods] Posted by: "jimclementssr" jimclementssrx~xxcomcast.net Date: Thu Oct 16, 2008 5:27 am ((PDT)) Has anyone been able to cut a 30tpi thread? I know it is not on the chart but I thought maybe a different combo of gears may achieve the result. I am trying to go into an existing piece that I cannot change the thread on, so I must thread the new piece to the 30 tpi. Any suggestions would be great. Jim ------- Re: Threading Question Posted by: "Kevin Jones" krjone01x~xxaye.net Date: Thu Oct 16, 2008 6:06 am ((PDT)) LMS has a calculator for just about any TPI you can imagine: http://www.littlemachineshop.com/Reference/change_gears.php For 30tpi it gives three possible gear combinations: A B C D 20 60 80 50 40 50 40 60 40 60 40 50 Just remember that the threading dial will not work with this TPI. You'll have to keep the carriage engaged to the lead screw and run the carriage back to the start by putting the motor in reverse for each cutting pass. (Don't forget to retract the cutting tool when you do that.) Regards, Kevin Jones Louisville, KY ------- Re: Threading Question Posted by: "John Stanton" johnsx~xxviacognis.com Date: Thu Oct 16, 2008 11:16 am ((PDT)) A very good solution would be John Dammeyer's ELS Electronic Lead Screw kit. It comes out of Canada and sells for about $200. You supply the motor, power supply and spindle position encoder. http://www.autoartisans.com/ELS/ JS ------- Re: reversing switch [atlas_craftsman] Posted by: "Robert Silas" robert.silasx~xxvideotron.ca Date: Sun Dec 28, 2008 3:54 am ((PST)) I don't know how many members of this group are doing production work? Most of us, I think, using machinery as part of our hobbies. I am old enough to remember what a great job the old masters turned out on primitive machines in my grandfather's shop about 70 years ago. They did not even have a digital caliper. How often do we cut threads on a lathe?? (There are exceptions of course). I am using two lathes (not in the same time). When the 13 x 47 QC lathe is set up for a particular job and suddenly I have to make something else for the job, I do it on the 10 x 24 Atlas, which has change gears only. Once you got used to changing those gears, an extra 10 minutes would do it. Seldom I have to cut threads, mostly metric threads. To see the depth of the cut I use a permanent, thick, felt tip pen to paint the surface of the finished shaft. Then, besides reading the dial, I can see the depth of the cut by watching the narrowing of the black mark. Usually, I pre-cut a thread on the lathe and finish it with a die. I've gotten better results by using HSS for thread cutting. Robert ------- Re: Tapping an M5x0.8mm thread [taigtools] Posted by: "Steve Blackmore" stevex~xxpilotltd.net Date: Tue Dec 30, 2008 12:25 am ((PST)) On Mon, 29 Dec 2008 19:58:18 -0500, you wrote: >I have a piece of aluminum which I'd like to tap in order to use with a cheesehead M5x0.8mm screw. I already own the taps, but I did not know which size drill to use. Since I do most of my tapping in imperial (and for which I have a chart), I thought the machinist handbook could tell me what metric drill to use. However, I found the handbook to be overwhelming and confusing. The best I came up with was that the minor diameter for an M5x0.8mm was a min of 4.134mm and a max of 4.334mm thus an average of 4.23mm (FYI on P. 1798 of Version 28). Is this the best way to use the machinist handbook or is there a more straightforward way when seeking drill sizes for taps? A quick look at an online chart (i.e. http://www.newmantools.com/tapdrill.htm) confirms that 4.2mm is correct - but can someone confirm my logic? < Metric sizes are easy to work out, you subtract the pitch from the diameter, that gives you the tapping drill size. e.g. for 5x0.8 5 - 0.8 = 4.2 and for 4x0.7 it's 3.3mm, 6x1 it's 5mm etc. >My second question is how the heck do I drill a 4.2mm hole? As an American hobbyist, my metric drills are limited at best. I have a 4mm and 4.5mm. Should I round down and use a 4.0mm? I was tempted to just try, but thought I'd ask first. Don't want to ruin a good tap if I can avoid it! < Either use nearest equivalent number drills or buy the right metric sizes, they are cheap and readily available. Steve Blackmore ------- Gear Train for 6t.p.i. [MyMyford] Posted by: "ANGELA TYE" tye677x~xxbtinternet.com Date: Wed Jan 21, 2009 2:58 am ((PST)) Hi. I'm trying to make a thread of 6 t.p.i. with a leadscrew of 8 t.p.i. Does anyone know what the gear train should be? ------- Re: Gear Train for 6t.p.i. Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Wed Jan 21, 2009 4:03 am ((PST)) Any train that will give you a ratio of 3:4 (spindle speed:leadscrew speed). Regards, Tony ------- Re: Gear Train for 6t.p.i. Posted by: "Frank Chadwick" fr4nk.chadwickx~xxtiscali.co.uk Date: Wed Jan 21, 2009 3:43 pm ((PST)) Angela, You want a system to give you six revs of the headstock for eight revs of the leadscrew. A 40 gear on the spindle and a 30 on the leadscrew would be fine but you have a problem in that you're gearing up to drive the leadscrew or in other words the myford isn't designed to cut such a coarse thread. If I were doing it I would drive the system backwards and cut the thread by manually cranking the leadscrew handle and using the gear train to drive the headstock. It will be hard work and you will only be able to put on very light cuts. Good luck. Frank C. ------- [Removing a tiny broken tap] Re: tap trouble -- another trepanning idea [sherline] Posted by: "Ron Ginger" rongingerx~xxroadrunner.com Date: Fri Jan 23, 2009 4:07 pm ((PST)) For a nice trepanning tool find a roll pin of the right diameter- roll pins are like dowels, but they are a small roll of very hard spring steel. They have a small slot along the length. Take your Dremel tool with a cutoff wheel and grind a couple of teeth on the end of the pin, to make a tiny hole saw. Two or three teeth are enough, and they don't even have to be perfect teeth. Just be sure they have the correct angles of a hole saw tooth. Now, here's the important part- grind the teeth LEFT HANDED. Put the pin in a drill, running left hand, and start to drill out the pin. Very likely the pin will catch the tap and unscrew it. If not it will still cut around the tap as deep as you want. This trick also works well for removing broken woodscrews. After you get it out write yourself a big sign that says NEVER TAP FREEHAND, ALWAYS USE A GUIDE. I routinely run taps as small as 4-40 under power in my Clausing mill with a VFD to control the speed. I also made a bench tap guide from an old drill press. I do not recall ever breaking a tap that was being guided. I do recall lots of broken taps before I started to guide them. ron ginger ------- Re: Metric gear set up for Ml7 [MyMyford] Posted by: "freddiefroggie" donaldjsmx~xxaol.com Date: Tue Feb 17, 2009 3:24 am ((PST)) Greetings all, Very close to Metric threads can be cut on an Imperial Super 7 with a gearbox by simply changing the gear on the spindle which drives the tumbler gears, with one which most of us will likely already have, no official Metric conversion set is required, and then selecting a suitable setting with the gearbox levers to get the pitch you want. I recently cut a 1.5mm thread for an ER25 collet closing ring by this method which is completely satisfactory. See Model Engineer item in Post Bag in Vol.168 No.3922 5-18 June 1992 entitled "Screwcutting Accuracy" by J.E. Walford and follow up article in Vol.169 No.3928 4- 17th September 1992 article by W.J. Faulks entitled " Accuracy In Screwcutting". A chart detailing the extra gear size and the gearbox lever settings necessary is printed in the M.E. articles. I must stress that the pitches achieved with this method are not 100% proper metric pitches but are probably near enough for most practical purposes. Purists please don't flame me. Keep making the swarf. Donald J. Mitchell Castle Douglas Bonnie Scotland. ------- Re: Metric gear set up for Ml7 Posted by: "Norman Atkinson" ravensworth2674x~xxyahoo.co.uk Date: Tue Feb 17, 2009 4:34 am ((PST)) And for the purists amongst us, the only correct metric threads which can be cut on a Myford have to use a 127 'transposing' gear -- and an accurate leadscrew. ------- Re: Fw: Tap Guide, 2MT Short [sherline] Posted by: "Alan Haisley" alanhyx~xxroadrunner.com Date: Tue Feb 24, 2009 9:45 am ((PST)) "Natividad, Eric" wrote: > Ian, Jerry, > Can you please enlighten us (newbie & in-experienced ) on these > tapping guide you are talking about. A link or a picture of it > would also be helpful. Thanks, Eric Look for the folder: "Tapping Guide" in the photos section. Those are intended to be used with a tap wrench of some sort. Another way is to clamp a disk to the tap shank, leaving some shank above the disk, and use the drill chuck set just tight enough to minimize wiggle. You can then make sure that the tap goes as straight as the drill bit did. This is hard to do with anything over about a #4-40 tap. For the larger ones, some better kind of clamp with a bit more leverage is useful. Sometimes I will start a larger tap as above until it gets too hard to turn, then remove everything from the mill and go to a bench vise and a regular tap wrench. If a larger tap is well started it will probably stay straight in the hole. Alan ------- Re: Fw: Tap Guide, 2MT Short Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Tue Feb 24, 2009 10:11 am ((PST)) Alan, another good tip in regard to: "it will probably stay straight in the hole" There is NO guarantee of that. Use a good machinist's square as you go (at 45 degree intervals) to insure that the tap is perpendicular to your work. You might have to remove the tap wrench to ascertain this. Correct (gently) as you tap. Later, Jerry G (Glickstein) ------- Tapping on a Sherline Mill [sherline] Posted by: "n2562001" jlkiefferx~xxcharter.net Date: Tue Feb 24, 2009 7:16 am ((PST)) Personally I have not seen a practical commercial solution For Tapping holes in a Sherline Mill. There are three issues when tapping holes on this machine. First the tap needs to be held in alignment. Second you need a practical method of turning the tap. And third you need to deal with limited clearance between the work piece and spindle. Commercial solutions I have seen to date tend to be time consuming and have not dealt with the real issues As I see them on a Sherline. My personal solution to these issues is as follows. I first purchased 3' of 13/32" drill rod that is a slip fit to Sherline's spindle Bore for about $6.00. I then cut off about 10" and drilled a 3/16" cross hole on one end and friction fitted a 2" long 3/16" "Tee" handle. On the other end I drilled a hole and fitted a cut off "Clock Key" arbor that fit common Taps that I use. The Clock key arbor can be held in place with a cross pin or set screw to change arbor sizes or additional tools can be made. Clock keys cost about $3.00 each and are available in all sizes needed for typical tap holding on a Sherline Mill. In operation the hole to be tapped is drilled. The proper tap is then set in the hole and the tap tool (Described above) is inserted at the top of the spindle. When engaging the tap it is held in alignment with the hole. The "Tee" handle at the top of the spindle allows for very easy sensitive turning of the Tap. In addition the system allows up to zero clearance between the work and the spindle nose. The Tap can be fully extended up inside the spindle bore while being held in alignment and still easily turned in and out. Since I use WW/8MM collets on a regular basis, I also have Tapping tools that fit inside my WW drawbar saving much time when tapping small holes. Jerry Kieffer ------- Re: acme threads [atlas_craftsman] Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Fri Feb 27, 2009 10:17 am ((PST)) pflatlyne wrote: > Does anyone have any pointes for cutting acme threads. Ive been trying > to cut some and keep having problems. Ive made three attemps so > far,fixing the problem that screwed me up the last time,but these seem > a somewhat harder to do than regular threads. Absolutely, they are harder. Flexible lathes don't like taking cuts where you get a wide chip. One way to do this is to make the form tool narrower than the full Acme tooth profile. You can then use the compound to offset the tool and take a little off each flank at a time. Jon ------- Re: acme threads Posted by: "VTatlasLathex~xxcs.com" Date: Fri Feb 27, 2009 11:34 am ((PST)) I've cut a fair amount of acme threads. Best investment I ever made was to get a threading tool that took preground insert tooling cutters. You need to take light cuts and use a lot of cutting fluid. I find the rocker style toolpost to be better for threading on the Atlas than a quick change, which seems to magnify the weakness in the compound rest. Take out the wedge, turn the washer over and shim up thee tool as needed. I love my Atlas, and still use it all the time, but the second best investment I ever made for Acme threads was to get my South Bend Lathe. Dave ------- Re: acme threads Posted by: "doc" n8as1x~xxaol.com Date: Fri Feb 27, 2009 5:30 pm ((PST)) Since a Canadian master machinist visited me several years ago, I have cut all acme &square thrds using the "Britt "method .....USE HIGH SPEED bits ...grind the bit w/ correct angles but undersize ( maybe 20% ) set the compound parallel to spindle .....use x slide to cut to FULL DEPTH ...now u use the compound taking lite cuts of a few thou, right /left cleaning up the thrds & cutting them to full size checking against ur nut. The thrds are now clean & u didn´t have to go go crazy grinding to xact size, just get the angle correct Best wishes docn8as ------- NOTE TO FILE: The following conversation is part of a much larger one dealing with a mysteriously modified Atlas with an extra lead screw. Here I have extracted some observations and a tip that could be useful for threading on any lathe. ------- Re: Twin Screw 12" Craftsman 101.28910 [atlas_craftsman] Posted by: "Robert Silas" robert.silasx~xxvideotron.ca robsi39 Date: Fri Mar 6, 2009 6:43 am ((PST)) Robert Silas wrote: >> I cut M 1.0, 1.25, 1.5 mm threads with the change gears as given in the >> table of the 10" Atlas. No need for another screw, for all practical >> purposes the above mentioned threads are perfect. Jon Elson wrote: > But, you can't disengage the half nuts, you have to back up the lathe > and leadscrew for each pass. And, your threads are not precisely > accurate, only workable approximations. If you tried to cut longer > threads and nuts, they might jam. Jon: Yes, I know about that, but so far I did not need to cut long threads, probably I could not even do it, never done it. According to the Atlas manual some of the threads are only out by one thread at the 3,000-th. With a 40/127 set up 1.0 mm threads with an 8 in one pitch lead-screw would be perfect and 50/127 would yield 1.25 and so on. I needed, so far, about 1.5-2" long threads and for that length it worked the way Atlas said. Yes, I could not open the lock once it is closed. But I have to confess that it happened that accidentally I opened the lock. I still continued the same thread by lock the half nuts, back the carriage to take up all backlash, use the cross and compound slides to adjust the tool into the thread, withdrew the tool, backup the carriage by turning the counter-shaft by hand (before I reversed the motor) and completed the thread. These were 1, 1.25, 1.5 mm threads. When I was finished with it I passed the die over it. I am not such an accurate turner than some of you guys. I am doing something, which I never heard from anybody else. Before I start cutting I pass a black marker over the whole finished rod, painting it black. As a second check, not to make a mistake and cut too deep, I am watching the narrowing of the black (top of the thread). If it completely gone I ruined the thread. Depending on the contact percentages of the thread a very thin black should remain. Is this stupid?, but it helps. Robert ------- metric screw pitches, (was in twin screw 12") [atlas_craftsman] Posted by: "jerdalx~xxsbcglobal.net" Date: Sun Mar 15, 2009 7:51 am ((PDT)) Original Message ----- From: Sent: Sunday, March 15, 2009 12:23 AM Subject: [atlas_craftsman] Re: Twin Screw 12" Craftsman 101.28910 > Actually, if you look at typical metric threads virtually all pitches above 2 mm are increased in 1/4, 1/2, or 1 MM steps. For the most part this includes 1 to 2 mm with some exceptions. The real *metric only* steps exist primarily below 1 mm. The difference is the steps in metric pitches are multipliers whereas in inch threads they are dividers. Anthony Berkeley, Calif. < First, your 1mm is the PITCH, and not the screw size. So the huge majority of useful screw sizes for small and medium work, up to about 6mm (roughly 0.236" dia screw) all suffer under these increments of 0,1mm steps. Second, the quarter mm steps are not terribly relevant. They make no difference to the thread dial complexity, since it is already required. Apparently the metric system originators rigid little minds could not accept the multiplier-based turns per unit system. They must have it "properly divided" into "rational divisions", meaning something to do with 10..... Too bad they really didn't actually USE "rational" divisions, which would have been ratio-based.... ;-) The newer IEC preferred number series might have been another potential good basis for threads. I have not checked it in detail as a threading system, but it has at least the good feature of repeating the same ratios. In the English system, once you have one set of numbers, all the rest follow. You have the coarse pitches, such as 8 or 9, 10, 11, 12, 13, 14 . Then those REPEAT as 16, 18, 20, 22, 24, 26, 28, and repeat again as higher TPIs, each with a simple 2:1 multiplier. Yes there are legacy oddities, but in the main they are repeating ratio increases. With metric, you have M2 x 0.4 M2.5 x .45, M3 x 0.5, M4 x 0.7, and M5 x 0.8 . Then M6 x 1, M8 x 1.25, M10 x 1.5, M12 x 1.75, etc. There is no common multiplier set, no standard ratio of increase, most every one is "unique" until large pitches are reached. Taking the first few, 0.4 leads to 0.8, 1.2, 1.6, etc. Only one of those is a "real" thread. Then 0.45 leads to 0.9, 1.35, 1.8..... no help there. Obviously 0.5 does hit a number of real threads when multiplied, but 0.7 (1.4, 2.1, 2.8, etc) does not, and 0.8 (1.6, 2.4, 3.2 etc) is likewise of no help. So all the turns per inch also repeat as inches per turn, in ratios that allow the thread dial to have ONE gear. With metric they do not until you reach the sizes limited to heavy machinery and structures. Naturally, this also complicates the adaptation of an english pitch machine to metric, as with the Atlas. The 127 tooth gear makes the basic change, but then it becomes much more chaotic when trying to achieve a specific metric pitch. JT ------- Re: metric screw pitches, (was in twin screw 12") Posted by: "Robert Silas" robert.silasx~xxvideotron.ca Date: Sun Mar 15, 2009 10:33 am ((PDT)) Thanks JT, this is a great comparison and summary of the facts, I really like it, never thought about it this way. I worked in both systems. Both systems have their shortcomings and their advantages. In both systems people completed great projects. Today, after working in the English system for over 50 years, I prefer it to the metric one. Regarding drill bit sizes metric is simpler than the "number-drills" and the "letter drills". I am in structural steel where the smallest unit is 1/16, which is considered a round number in fabrication, not in engineer- ing calculation. We don't have to take care of decimals in fabrication. In my hobby of machining I use both systems. Canada converted into the metric system for no good reason at all. I kept working in the English system. I refused to accept the changes in the metric system, the new Nm, Kpa, etc. What was wrong with cm, deci-liter, kg, etc???. Giving section-modulus and inertia in mm .... wild. Robert ------- Re: metric screw pitches, (was in twin screw 12") Posted by: "jerdalx~xxsbcglobal.net" Date: Sun Mar 15, 2009 6:37 pm ((PDT)) At work, I use metric almost exclusively, and like it, converting only when a panel layout, etc, is easier to do in english. I just use the Autocad 'scale" function and "shazam" it's all there in whichever I want. At home, I have measuring tools both ways, but inch calibrations on all the feeds, so I have to convert when making work protos in the shop here at home, or otherwise having metric input. The threads issue is a sore spot, I think they really blew it. But it's a done deal, so....... JT ------- Atlas QC gearbox for Metric and Imperial (was metric screw pitches ) Posted by: "carvel webb" carvelwx~xxabsamail.co.za Date: Sun Mar 15, 2009 9:10 am ((PDT)) All: Looking at this discussion, if one has a need for the more common 1mm, 1.25mm, and 1,5mm pitches, and the 52/44 conversion ratio used by Atlas is acceptable, then the article which I wrote in 2006 which is in the files section might be of interest. Repeated here for convenience - Regards, Carvel " A 30 second "Metric Conversion" for the Atlas 10" lathe fitted with the Quick Change screw cutting gearbox. One of my main interests is the restoration of classic cars and motorbikes, but as fate would have it, of both European and British origin - which involves fabricating small parts with both Metric and Imperial threads. Although I also have a largish lathe with a full Metric and Imperial gearbox, it is a bit clumsy for smaller threads, and I had often looked longingly at the gearbox on the Atlas and wished it read "mm" instead of "tpi" ! This prompted me to start reflecting on whether some form of easily implementable, and reversible, approach was not possible which would allow the cutting of the most often used smaller Metric pitches of 1mm, 1,25mm, and 1,5mm. The problem with most Imperial gearboxes is that the tpi intervals don't readily equate to any Metric pitch intervals - with one exception. While most Imperial gearboxes (Myford, South Bend , Smart and Brown etc) would typically include a range of say 16 to 28 tpi, Atlas in its wisdom extended this similar range to 30 tpi. In staring at these figures and playing with the ratios, I realized that 30 tpi / 24 tpi / 20 tpi represented the same ratio intervals as 1mm / 1,25mm / 1,5mm , and so the seed was born. If one could easily convert 30 tpi to 1 mm pitch, then the 24 tpi and 20 tpi positions would correspond to 1,25m and 1,5mm respectively, giving the three most needed ranges (in my case). 30 tpi = 25,4/ 30 = 0,8467 mm , but how to get this to 1mm ? Atlas to the rescue again courtesy of their 52 and 44 tooth gears with 0,8467 x 52/44 = 1,0006mm - what a pleasure, and close enough for most purposes. The next obvious question was how to introduce this into the gear chain in the least painful way. Examination of the standard set up for driving the Quick Change box from the spindle reveals that the tumbler gears include a 32/16 shielded gear which in turn drives a 40 tooth sliding gear, which in turn drives the box through a back to back pair of 48 tooth idlers. The 52/44 combination fits quite neatly in place of the 48/48 idler, and herein lies the trick. With the 40 tooth sliding gear engaging the 52 tooth gear to the box, the 52 tooth gear is acting as an idler, (with the 44 tooth gear as its spacer), and the gearbox operates in its normal 'Imperial Mode' with the exception of the coarsest (seldom used) range. However with the 40 tooth sliding gear in the other position, it engages the 44 tooth gear of the 52/44 combination and introduces the 52/44 ratio into the chain driving the box. The 30 / 24/ 20 positions, or 60 / 48 / 40 positions, become the desired 1mm / 1,25 mm / 1,5 mm pitches, depending on whether the 52 tooth gear of the 52/44 pair has been placed closest to, or away from, the headstock. In my case, I placed it away from the headstock to maintain the bulk of the tpi and feed settings as per the chart on the gearbox, so as not to have to remember to double everything as would be the case if the sliding gear was driving off the 32 tooth part of the shielded tumbler gear. All that is required to switch between the normal "Imperial Mode" and the "Metric Mode" is the few seconds it takes to loosen the yoke, and to move the sliding gear in or out. Have fun, and hopes this adds to the pleasure and convenience of your Atlas lathe if you have the same need. Carvel (Johannesburg South Africa) ------- Re: Atlas QC gearbox for Metric and Imperial (was metric screw pitch Posted by: "Robert Silas" robert.silasx~xxvideotron.ca Date: Sun Mar 15, 2009 10:58 am ((PDT)) Carvel: On the 10" and 6" Atlas lathes I only have change gears. I am playing with European motor bikes where metric is the standard. A few times I needed to cut metric threads, those three you mentioned, and I am used to changing gears, no big deal, not something I need to do every day. On the 13" lathe I have a QC box. In three years I used it twice for threading but it is handy for changing feed-speed/rate. Unless you are in production, QC is only a convenience, not a necessity though it's nice to have. Robert ------- Small Tap Alignment [LittleEngines] Posted by: "Gary Briggs" briggs451x~xxyahoo.com Date: Sun Apr 12, 2009 7:58 am ((PDT)) Here's an easy way I've found to hold small taps in alignment. It uses two telescoping brass tubes, the larger tube is held in the mill chuck and the smaller tube engages the conical top end of the tap through the top side of the tap wrench. When finished drilling the tap holes, I leave the work on the index table and rotate the work to each hole to be threaded. Then I place the tap and slide the smaller tube down on the end of the tap. This holds the tap in perfect vertical alignment without any pressure on the tap that would obscure the "feel" of it. As the tap progresses down into the work, the smaller tube simply slides down to remain engaged with the tap. I scored the sliding tube with 0.1" marks to aid in tapping blind holes. I've posted a photo in the Miscellaneous Album here. The photo shows the work, a brass six-lug hub, with four holes already threaded, the #0-80 tap positioned in the fifth hole, and one hole to go. Works great - cheap, easy and fast, and I haven't broken a tap or spoiled a thread yet. You can get assorted small brass tubes at most hobby stores. ------- Tapping Group Started [posted in DIY-CNC group] Posted by: "Cliff. Johnston" moments-in-timex~xxcomcast.net Date: Tue Apr 28, 2009 10:59 am ((PDT)) I have a project that involves tapping many small holes. I asked an "old pro" for some advice on tapping them. He told me that his tapping machine was one of the best investments that he had ever made. I took his advice and bought a used Procunier tapping machine. It arrived late last night, and this morning I got it set up. Later I went online. I couldn't find a group dedicated to tapping heads/ machines, so I've started one. If you've ever thought about buying a tapping head or tapping machine (electric or manual), or if you own one and want to expand your knowledge about it and the subject of tapping, or if you've owned or currently own a tapping machine and know all about them and want to help, here's just the group for you: http://groups.yahoo.com/group/TappingHeads I invite you to join. Cliff. Johnston ------- Re: Tapping Group Started Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Tue Apr 28, 2009 8:12 pm ((PDT)) I have a Procunier "CNC" tapping head that I have used on my Bridgeport with CNC. I have some $8 thread-drills that can be used with this. The tapping head has forward and reverse clutches activated by pressing the tap forward or pulling back, respectively. The "CNC" version has no overload clutches or leadscrew; it expects the CNC machine to feed at the right rate to keep up with the tap's thread pitch. As long as the spindle is running a little faster than the programmed Z feed, the clutch will slip a little to maintain sync. The only problem with this setup is that it is so long that it almost exceeds the height over table of my Bridgeport. But, it was TOTALLY cool to spot, drill and tap many holes in one setup, at 1200 RPM! Well, I have this 150-Lb mini-mill (sometimes called an X2) that I tote around to shows to demo my CNC electronics hardware, and it is really easy to rig an encoder to the spindle, unlike the Bridgeport, where massive machining would be required. So, I rigged an encoder to the spindle with a little belt, and connected the spindle motor to a servo amp so I could reverse it under program control. Now, I use it for rigid tapping, and it works out really well. I just put the thread-drill in a Jacobs chuck, so the stack-up is much more rigid and well centered, and the hole position doesn't wander at all. With that long stack with the Procunier head, I think the hole positions tended to wander a little, and I was always worrying that if the thread drill started the hole off-center enough, it would break the tap off. So, if you have a CNC machine, there are a couple ways you can do tapping right on the CNC machine in one operation. Jon ------- broken tap [atlas_craftsman] Posted by: "wheezer" wheezer606x~xxverizon.net Date: Mon May 11, 2009 7:15 pm ((PDT)) Group, I have a 3/16" tap broken off in a bored through hole in a steel block. The hole is in the exact spot to hold a vertical vise for a cross slide milling attachment I am making. The broken tap is hard to drill due to its small diameter and its hardness. I was hoping to drill it and use an EZE-Out. Anybody have any ideas how to get the tap piece out without ruining the hole? lance ------- Re: broken tap Posted by: "Richard Hughson" loopyrichx~xxyahoo.com Date: Mon May 11, 2009 7:48 pm ((PDT)) EDM is great and can definitely remove the tap. But if you've got the touch, and are lucky, you can try a tap remover / extractor. It's a small tool with rods that slide down along the grooves of the tap to get hold of it and give you a chance to work it back out. Again, you have to have a fine touch and be lucky. Here's a link to one I found by Googling 'tap extractor'. http://www.wttool.com/product-exec/product_id/26277?utm_medium=cpc&u tm_source=froog With a through hole you can sometimes work it from the other side as well. If you can gently tap it loose so it wiggles you'll have a better chance. Good luck, Rick ------- Re: broken tap Posted by: "bill phelps" sweetwaterent2000x~xxyahoo.com Date: Mon May 11, 2009 8:14 pm ((PDT)) If you have a Dremel tool with a small grinding wheel and are very careful, that will work. ------- Re: broken tap Posted by: "Michael Fagan" woodworker88x~xxgmail.com Date: Mon May 11, 2009 8:57 pm ((PDT)) I have had the most success with a solid carbide spade drill in a very rigid setup (good drill press or vertical mill). You need to feed about 0.005" per peck, usually against a stop. Any faster and you will break the drill. Once you drill out the minor diameter of the drill, you can chip out the rest with a chisel. ------- Re: broken tap Posted by: "jerdalx~xxsbcglobal.net" Date: Mon May 11, 2009 9:12 pm ((PDT)) Tap extractors are a sick joke...... Don't waste a moment of time, or any money, on them. They do NOT work except in the most simple of cases, cases where you can just about shake the tap out of the hole. When a tap breaks, it nearly always shatters with at least one piece, part of a flute, which is split-off at least partly down the length of the stuck part. That means that no matter which way you turn it, the split-off piece will probably act like a "sprag clutch", turning slightly, jamming, and siezing the whole works in the hole. You can drill it out, if it is mostly in one piece, or edm it out, or shatter it more with a punch (pulling out the pieces), or maybe heat it and draw its temper if it is carbon steel (then drilling) or weld a nut on it and try to turn it out. But a Walton, or other tap extractor will almost never work. JT ------- Re: broken tap Posted by: "TCHarex~xxaol.com" Date: Mon May 11, 2009 9:36 pm ((PDT)) This guy has the right idea, first try a tap extractor. Another guy suggests using a Dremel tool with a stone, this is also a good one, especially if you can mount the work piece and the tool. Mounting the tool on a vertical mill is excellent, but most of us don't own one. Another idea is to use a tig or mig welder to carefully heat the part of the tap that is at the center of the X that makes the flutes of the tap. Alternate heating and chilling can melt part of the center and also cause cracking in the tap. Just make sure you ground the tap, and not the work piece, or you might just weld the tap into the hole! It has been my experience that yelling and cursing are of only very limited value, but I have only applied these methods using the English language so my experience here is limited. Good Luck Tom ------- Re: broken tap Posted by: "Richard Hughson" loopyrichx~xxyahoo.com Date: Mon May 11, 2009 9:44 pm ((PDT)) Well, as I say it takes luck in how it broke and what kind of touch you have. A lot can be done with a thin punch. I've made many by grinding own an Allan wrench to the shape and size needed. Taps are very hard and brittle, as you have found, and very difficult to drill. The 'sprag clutch' effect can be incredibly frustrating. This can really test your patience so clear out all the chips you can and think your way through. It's surprising what can be done with a massive continuous effort. Good luck man. Rick ------- Re: broken tap Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Tue May 12, 2009 8:22 am ((PDT)) This (breaking off inside a through hole) is about the only situation where I've had a tap extractor work, as long as the tap broke because the shank was bent over and not because the tap was jammed. As for clearing out the broken tap the fastest way for me is to use a carbide tool to get it out. I usually start with a drill or center- cutting endmill a little over the body size of the tap and peck it out with an air blast in the hole. Watch out if you do that as the teeth will be coming out at a pretty good clip. If the tap didn't engage much before breaking I have just bashed it out from the far side, the few teeth in the work will usually break off. You have to be pretty careful cleaning out the few threads afterwards, a small bit ot the old tap will often cause the next tap to break off in a hurry. Finally, if the hole is small and I can't clear the old bits I'll run an oversize carbide tool though the hole and TIG in material to fill it. The new material usually threads better than the old (I tell myself that anyway). If you have a lot of time in the job and nothing else has worked take the part to a shop with a tap burner. It's a cheap EDM designed to pop a tap out of a hole, not caring about the quality of the hole in the tap. They shouldn't charge much for the work, but remember that they have to charge shop time to most anything that comes in or they can't pay their bills. ------- Re: broken tap Posted by: "jmartin957x~xxaol.com" Date: Tue May 12, 2009 9:00 am ((PDT)) You've had some good suggestions. One thing that will not work is the Easy-Out you mentioned. The flutes in the tap necessitate that the hole you drill for the Easy-Out be so small that the Easy-Out that fits will be a ridiculously small size. There are two tricks to using an Easy-Out: 1. use the largest size you can, BUT, 2. make sure that the shell you leave is not so thin that the Easy-Out will expand it and lock it in the threads. Also, an Easy-Out has to be able to bite into the broken piece, and your tap is probably about the same hardness as the Easy-Out. As Russ and some others mentioned, the nature of the tap and the circumstances of the break are important. If the tap broke because you bent it, a tap extractor may very well work. If it broke due to jamming in the threads, the tap extractor may not work. If the broken piece is short and the tap is carbon steel, shattering the tap with a punch is possible. HSS is tougher and doesn't shatter as easily. You might try a saturated solution of alum in hot water. This is sometimes used to remove broken taps in aluminum, as it will attack the steel but not the aluminum. In your case, it will eat the threads of the workpiece as well as the tap. If it eats too much away before it loosens the tap, re-tap for a helicoil or the next size screw. Drilling with a carbide drill or end mill is an option. Especially as you can drill from both sides. Drilling from the bottom with a RH cutter may even grab the tap and thread it back out. From the top, drill with a LH cutter if you have one. EDM will of course work, but if you had that at home you wouldn't be asking. John Martin ------- Re: broken tap Posted by: "Jerry Freeman" jerryx~xxtcenet.net Date: Tue May 12, 2009 9:30 am ((PDT)) Is this something you can heat cherry red without damaging it? If you can heat the part hot enough to anneal the tap, then you could drill it out. If you don't have a suitable torch, you can build a big enough wood fire somewhere, leave the part in the fire till it's glowing brightly. Take it out and let it cool (don't quench). Drill the tap out. Best wishes, Jerry ------- Re: broken tap Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Tue May 12, 2009 10:07 am ((PDT)) > Is this something you can heat cherry red without damaging it? That would work on a carbon steel tap, but doesn't have a chance with a HSS tap. Unless the tap was very old or a special order (or, perhaps, a real cheap import) it is unlikely to be a simple carbon steel. Grinding the stub would tell you the difference; you get a brighter streak and spark from high carbon than HSS. ------- Re: broken tap Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Tue May 12, 2009 12:02 pm ((PDT)) On Tuesday 12 May 2009 Jerry Freeman wrote: > I did some looking around, and here's what I found: > "High-speed steel is softened by annealing at 850°C for about > four hours, followed by slow cooling." > http://steel.keytometals.com/Articles/Art8.htm > Perhaps the time factor (four hours) is the key? It would have had to be > soft enough to machine at some time in its history, so it seems like it > should be possible to return it to a machinable state. It might work, but remember that the soak time for the tap *starts* when the soak time for the steel piece ends. Also, the drop in temperature can't exceed something pretty small (I recall 25degF/hr, it might be a bit more) or you have to start over again. Also, all this has to be done in an inert atmosphere or at least bagged (I'm not sure that the bag would like 4+ hours at 1600 degF - that's up into the "yellow" range). You're talking about some fairly specialized equipment that he's not likely to have, and something not needed if you put $10 into a carbide drill or endmill. Let me know if you do it, and if it works. I see people suggest it but have never heard of anyone actually trying it. ------- Re: UPDATE broken tap Posted by: "wheezer" wheezer606x~xxverizon.net crashbone256 Date: Tue May 12, 2009 2:14 pm ((PDT)) Broken Tap Update Tried and didn't work: HSS drill end mill carbide tipped drill cold chisel EZE-out I will buy a better quality carbide drill tonight. For now, I have made another angle brace and the original becomes a project for later. Thanks for all the ideas. I tried the EDM concept with a homebrew and I can see that it would work, but I'd have to send the brace out to be fixed. I don't have time to build an EDM. lance ------- Re: UPDATE broken tap Posted by: "jmartin957x~xxaol.com" Date: Wed May 13, 2009 8:52 am ((PDT)) wheezer606x~xxverizon.net writes: > Broken Tap Update > Tried and didn't work: If you have tried the Easy-Out you obviously have drilled a hole through the center of the tap. That's the hard part. If you were able to do that, I'm surprised the tap is not out. Drill the hole larger until you hit the flutes, and the pieces of the tap will fall out. John Martin ------- Re: broken tap Update Posted by: "wheezer" wheezer606x~xxverizon.net Date: Sat May 16, 2009 5:06 pm ((PDT)) On May 14, 2009, Mrs Leon Robinson wrote: > L. H. > I concur, where I used to work Tap Magic for Aluminum is the best > thing for aluminum. Leon K5JLR Group, I bought a gallon of Tap Magic Aluminum. The tap was broken in steel however, the trick for me was to DEEP FREEZE the piece. Couple of days in the deep freeze, then used a spade-pointed carbide bit and the right slowish speed and it ground the broken HSS tap out. It took two days, because the tap heated up during the first half of the drilling, and I put it back into the freezer. So, the tap is out, the hole is reamed oversized and life does on. Thanks for all the ideas ... obviously this has happened before? lance ------- Re: broken tap Update Posted by: "wheezer" wheezer606x~xxverizon.net Date: Sun May 17, 2009 5:43 pm ((PDT)) On May 17, 2009, Richard Hughson wrote: > Way to go Lance, but I'm a bit lost. How did the deep freeze help? > Were you using temperatures that were liquid nitrogen deep? Rick Rick: You're lost now, wait until you follow my logic here?! Many of the tap removal suggestions were based on the brittleness of the HSS tap. My previous attempts to drill out the tap were brought to an abrupt end when either the carbide tip shattered or the HSS drill bit rounded off. If brittleness was the characteristic that separated the mild steel from the tap, then if I froze the whole block, that would increase the brittleness of the tap and I could whack it with a hardened concrete nail and shatter it. Yo ho ho, the concrete nail bent in half. So, let's try the last carbide bit in the box with the hand drill in the basement (nearest drill to the freezer). The drill's battery was low, so it turned slowly, but wonderation... the bit didn't shatter and tap dust started to emerge from the hole. About when the drill battery died, the carbide tip was getting grabby with the tap. The block goes back in the freezer, the battery on the charger and next day... whack-a-mole, no tap, just hole. It's Tap Magic! lance ------- Taps [semi-OT] [MyMyford] Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca kstrauss7 Date: Sun Jun 21, 2009 4:42 pm ((PDT)) I've decided that I need to have taps in Myford standard sizes -- 1/4 BSF, 7/16 BSF, 3/8 BSF, 2 BA -- so that accessories can use the same wrenches as the lathe. I have no need for additional tap handles so I hesitate to purchase sets that include them. There are dozens of suppliers including Tapdie, Tracy Tools, Newman Tools, Engineers Toolroom, Chronos, etc. What is a good source for quality taps for a Canadian customer? ------- Re: Taps [semi-OT] Posted by: "John Stevenson" johnx~xxstevenson-engineers.co.uk Date: Sun Jun 21, 2009 4:58 pm ((PDT)) Tracy tools as the chances are you will get surplus taps as opposed to Indian made ones because BSF isn't used much any more hence they probably still carry surplus. BA will probably be imports. Bought some 7/32 x 24 the other week and got Osborne taps, which were a good UK brand at the time. John S. ------- Re: Taps [semi-OT] Posted by: "Roman Gargulak" romanx~xxcncwings.com roman_gar Date: Mon Jun 22, 2009 2:52 am ((PDT)) Ken, I bought some odd sizes from e-taps in the past. Their web site is http://www.e-taps.com/ and they have Whitworth taps and dies as well. Roman in Ottawa ------- Re: Taps [semi-OT] Posted by: "jwgott1" jwgx~xxleonard.com jwgott1 Date: Mon Jun 22, 2009 7:04 am ((PDT)) Try British Tools & Fasteners Co. in Lyons, NY. I use them for all my British size tooling, taps, dies, nuts and bolts. A family run business and very nice folks. http://www.britishfasteners.com/mm5/merchant.mvc Jonathan Bethesda, Maryland USA ------- Re: Taps [semi-OT] Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca kstrauss7 Date: Mon Jun 22, 2009 7:08 am ((PDT)) Wow, their prices are impressive! I'm reading their price list at http://www.e-taps.com/Ofertapage%20050.html At least they are HSS made in Poland instead of India. British Fasteners http://www.britishfasteners.com has BSF taps for much less but they provide no information regarding their sources. Tap-Die http://www.tap-die.com/ has their "EXCELLENT superior quality" taps for Ł3 to Ł6 [2009 prices] in the sizes that I need or Ł28 ex-VAT for six in a metal box. Has anyone purchased from them? Arc Euro http://www.arceurotrade.co.uk/default.aspx BSF/HSS-716x18-BSF-3pc-TiN-Coated-Tap-Set has 3-tap sets in HSS for about Ł8. Are these Indian? Tracy Tools http://www.tracytools.com/ has BSF taps for Ł2 to Ł3 but they don't list overseas shipping charges.. ------- Re: Taps [semi-OT] Posted by: "rrh0001" mollygeorgiex~xxmac.com Date: Mon Jun 22, 2009 6:37 pm ((PDT)) Hi Ken An excellent local source of individual taps and dies in HSS is Taylor Tools in Cambridge Ontario. Not cheap but quality rarely is. Their website is: http://www.taylortool.com I've bought a number of BSF and BA taps and dies from them for my Myfords and have been pleased with the quality. It's also nice to be able to just drive over and pick them up....(Phone first for pricing and stock.) Ramsay ------- A breadcrumb trail through the thread/spanner forest? [MyMyford] Posted by: "obald102" obaldx~xxihug.co.nz obald102 Date: Mon Jun 22, 2009 2:10 am ((PDT)) Not a post here for a while as I beaver way in the barn. Recent acquisitions feature a white grinding wheel and a diamond dresser which have been the best things I have purchased since the ML7 itself. Also arrived from the UK is a set of gear wheels and under the encouragement/ cyberspace guidance of an antipodean expert I have started thread cutting. As with all I have encountered thus far, crossing this hurdle has revealed further hurdles as far as the eye can see. All good - I wouldn't want it any other way. However I am much confused by threads and in particular what is current and what is still wearing the wide lapelled suits of the 1940's. The ML7 is an Imperial lathe and so Metric theads are hard. Correct? Without a 21T change wheel or two these threads are pretty much an impossibility? No problem. Large threads cut on a Myford are BSF and small ones BA. Still correct? Where does Whitworth fit in? What non metric threads are still being used in the 21st century? If I am going to cut threads de novo on any work I may do on my Imperial lathe in 2009 what thread system am I going to use? How are spanners measured? AF means 'Across the Flats' does it not? I assume this measures the bolt/nut head. How are old British spanners measured? If the spanners that came with the lathe are anything to go by they have two appellations, BSF and Whit, so I assume they rely on measuring the threaded part of a bolt in some way. If anyone could even point me in the right direction that I may ferret out some of the answers to the above I would be most grateful. ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Christopher Hicks" cmh21x~xxcam.ac.uk Date: Mon Jun 22, 2009 4:05 am ((PDT)) > The ML7 is an Imperial lathe and so Metric theads are hard. Correct? Yes. > Without a 21T change wheel or two these threads are pretty much an > impossibility? You can only get them exactly right with a factor of 1:127 somewhere in the gear train, and what with 127 being a prime number the only way of achieving that is a gear with a multiple of 127 teeth. However, if you don't need utterly precise threads then you can get pretty close to the right pitches with a 21 or 63 tooth wheel in the train (21 x 6 = 63 x 2 = 126 which is within 1% of 127, so there will be less than 1% pitch error if you do the sums right). If you only need a few threads in mesh and it is a non-loadbearing noncritical application this is generally fine. Remember though that there's the additional complication of not being able to release the half-nuts when you're working with awkward thread pitches. You have to wind the thread back by hand which makes the whole job quite tedious (I have only ever run my Myford in reverse under power once. Never again - it's not worth the risk of the chuck or faceplate unscrewing). > Large threads cut on a Myford are BSF and small ones BA. Still > correct? Where does Whitworth fit in? BSW = British Standard Whitworth BSF = British Standard Fine These are both imperial-sized thread series which were very widely used in Britain until the seventies. The spanners are sized according to the bolt sizes, so for example a 1/4" BSW 1/4" BSF are both bolts of 1/4" diameter (BSF is finer pitch than BSW - 24 and 16 TPI respectively if I recall correctly), and the correct spanner is irritatingly just slightly bigger than 1/2" AF. BA (British Association) is a bit of an oddity. It persists only in niche applications such as model making and clock making. The biggest size (0BA) is 6mm diameter 1mm pitch, but none of the other sizes are such convenient round numbers because they are derived from 0BA via a mathematical formula. > If I am going to cut threads de novo on any work I may do on my > Imperial lathe in 2009 what thread system am I going to use? I stick to imperial pitches where possible because it is so much easier on an imperial lathe, but you can really choose what you like. Quite a lot of folks (including me) cut threads with metric diameters but imperial pitches for one-off jobs; just don't expect to be able to pick up a tap or die to match! > How are spanners measured? AF means 'Across the Flats' does it not? Yes. > How are old British spanners measured? If the spanners that came > with the lathe are anything to go by they have two appellations, > BSF and Whit, so I assume they rely on measuring the threaded part > of a bolt in some way. Exactly. BSW and BSF spanners are measured by the bolt diameter. > If anyone could even point me in the right direction that I may > ferret out some of the answers to the above I would be most > grateful. Towards the bottom of this page http://en.wikipedia.org/wiki/Screwthread there is a section on thread standards which is reasonably good and contains some further links. Christopher Hicks ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Ian Newman" ian_newx~xxyahoo.com ian_new Date: Mon Jun 22, 2009 5:19 am ((PDT)) Hi, Regarding bolt head sizes, the following rules apply: Whitworth: Bolt diameter = D Across flats (AF) = 1.5 D + 1/8 inch Nut height = D Bolt head height = 7/8 D BSF dimensions are for one size smaller BSW e.g. 5/16 BSF is same size AF as 1/4 BSW This means a spanner will often be marked with both the above sizes. (From 1941 onwards the old BSW head sizes were dropped in favour of using the BSF head size - apparently this was to save metal during the war - so both a 5/16 BSF and a 5/16 BSW both have the same size head based on a one size smaller old BSW, that is 1.5 D + 1/8 where D is 1/4, not 5/16 - so that is nice and simple isn't it?) Metric - totally random relationship between head size and bolt diameter, due to the selection of head sizes to allow prefered sizes of standard hex bar to be used (most of the time). BA is the only truly logical system: 0BA has a pitch of 1mm and a major diameter of 6mm For any BA size N: Pitch = P = 0.9 ^ N Diameter = D = 6 P ^ 1.2 Head size = 1.75 D All very logical but resulting in really weird pitches and AF dimensions. Ian ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Bob Minchin" bob.minchinx~xxntlworld.com bobdownfield1 Date: Mon Jun 22, 2009 6:27 am ((PDT)) Ian, I'd not seen a formula for Whit/BSF hexagons before so I was intrigued and put yours to the test. Failed at the first hurdle I'm afraid: 1/4 Whit is 0.525"a/f not 0.5" as per your formula. I tried it all the way up to 1" BSW and no joy. I don't know where you got it from but it seems to be a dud! All the BA info checks out well though. Bob ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Ian Newman" ian_newx~xxyahoo.com ian_new Date: Mon Jun 22, 2009 7:49 am ((PDT)) Hi Bob, Yes - sorry, I should have typed "approximate rules". For the BSW calculation, the diameter used is the dimension that would be achieved if you took a bolt of the appropriate major diameter, but extended the thread form to a point instead of rounding the crest. From the thread form, the theoretical pointed crest would be 0.16 P higher than the rounded crest (where P = pitch). Therefore the diameter for calculation is nominal dia + 0.32 P For 1/4 inch 20 tpi this gives (0.25 + 0.32/20) * 1.5 + 0.125 = 0.524 (0.525 from tables) For 3/8 inch 16 tpi this gives (0.375 + 0.32/16) * 1.5 + 0.125 = 0.718 (0.710 from tables) For 1/4 inch 12 tpi this gives (0.5 + 0.32/12) * 1.5 + 0.125 = 0.915 (0.920 from tables) Still not perfect, I know, but better than the accuracy of the jaw width of my spanners. Ian ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "obald102" obaldx~xxihug.co.nz obald102 Date: Mon Jun 22, 2009 12:19 pm ((PDT)) And we built an Empire with that! I can just imagine platoons of sappers running round Rangoon with wheel barrows full of spanners trying to bolt back together all machinery that had spontaneously come unfastened. Anyway, thanks for all who have made a murky subject a liitle clearer. There is clearly no easy way of remembering all this on a bolt by bolt basis so tables would appear to be the go. Zeus? Dare I ask one more thing? What determines what thread gets what tpi? ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Barry Kneller" bkba09515x~xxblueyonder.co.uk Date: Mon Jun 22, 2009 2:14 pm ((PDT)) [gave link to a chart in 2009 for a now abandoned website] ISTR that there is a more comprehensive, 'spanner' chart on one of the other ME sites....If I can find it I'll post it up. ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Norman Atkinson" ravensworth2674x~xxyahoo.co.uk Date: Mon Jun 22, 2009 2:34 pm ((PDT)) My copy of Machinery Handbook has it all in. It is so old that it raises doubts about whether we- the Empire, would win the war. Not sure, I always thought that it would be the Golders Green Hippodrome not Hackney Empire. Well, really. N ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Ian Newman" ian_newx~xxyahoo.com ian_new Date: Mon Jun 22, 2009 3:41 pm ((PDT)) > Dare I ask one more thing? What determines what thread gets what tpi? Hi, there is a link between the thread pitch chosen for a particular bolt diameter. There are three mode of failure for a nut/bolt combination: The bolt can fail in tension (i.e. snap off at the root). The metal in the thread can be crushed (failure in bearing). Failure by shearing across the thread (stripping). The thread pitch is selected so when loaded to the point of failure, the bolt will fail in tension (unless the threads are damaged, in which case the failure mode may be through shear and the thread stripping). This is why you get high tensile bolts but never high tensile nuts. As the material used to make nuts and bolts improved, it was possible to use a finer thread without compromising the shear strength - the finer thread resulted in a higher cross sectional area to the bolt and so a higher tensile strength. The result was BSF which is a stronger nut/bolt combination than the same size BSW. This pitch/thread depth factor also influences the nut thickness - the nut should be thick enough to ensure that the bolt will fail in tension, before the nut strips. The interesting conclusion that you can draw from this is that it is pointless to make a tapped hole that is deeper than the thickness of the nut - the extra depth of threaded hole will not make the bolted joint any stronger. Before BSW, there was no common standard for threads, each individual manufacturer producing their own bolts. When creating his "standard" for threads, Joseph Whitworth researched the various threads used by other companies to find a selection of sizes that would cover everyones needs (and, I suspect, with pitches that his own company could produce without having to re-tool). To minimise the range of pitches, some pitches are used on more than one diameter. Ian. P.S. This is what made Britain "Great" (or should that be "grate"?) ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "anthrhodesx~xxaol.com" Date: Thu Jun 25, 2009 11:41 pm ((PDT)) Please, please, -- PLEASE --, don't do this. It's important to know when you don't quite understand the things you're discussing and to throw in a few caveats to that effect. In a message dated Mon Jun 22, 2009, Christopher Hicks writes: "You can only get them exactly right with a factor of 1:127 somewhere in the gear train, and what with 127 being a prime number the only way of achieving that is a gear with a multiple of 127 teeth." The above is correct. "However, if you don't need utterly precise threads then you can get pretty close to the right pitches with a 21 or 63 tooth wheel in the train" The above is also correct "(21 x 6 = 63 x 2 = 126 which is within 1% of 127, so there will be less than 1% pitch error if you do the sums right)." But this illustrates the misunderstanding. The math is correct but the application is wrong. When using a 127 to convert from inch to metric pitch it is used in the driven position, for instance 100 driving 127. For the sake of convenience reverse the calculation and divide 127 by 100, result 1.27. But when using a 63 for the same conversion it's used as a driver. The closest equivalent to 127 / 100 is 80 / 63 = 1.26984. To determine the error by using a 63 in this way rather than the preferred 127 divide 1.27 / 1.26984 = 0.99988 or 1-1/4 parts in 10,000. The gear trains for converting from inch to metric pitch using 63 as a driver can be calculated but there are readily available published tables for all the likely desired pitches. Christopher, I don't really mean to take you to task or embarrass you but it's a common experience that once something incorrect is stated on a forum such as this it takes on a life of its own and is quoted from then until doomsday, in the process interfering with actual understanding of the mechanisms being discussed. I've made my boners and felt pretty foolish after the fact so please take this message as well intentioned. Anthony Berkeley, Calif. ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Norman Atkinson" ravensworth2674x~xxyahoo.co.uk Date: Fri Jun 26, 2009 12:12 am ((PDT)) Time for more 'Archimedes'- I think. It's all right pontificting about Metric conversion in screwcutting with the magic 127, or the 63 (nearly) or 21 (key of the door) but the following happens in real life. Now listen carefully! 1. Fart about as much as one likes but a 127 20DP gear won't fit on a Myford. So you have to alter the diametrical pitch to make a smaller diameter - or put your head between your legs and settle for 63- or 21. But, the famous Myford lead screw pitch has to be exact. We are back to Archimedes. If the leadscrew is worn, putting a 127 gear in the system might be no more accurate than a --- dare I say it-- a 60-- and we don't have to bugger off the shop to get a 'funny' gear. Sorry- do your arithmetic-- and your measurements. A child's plastic rule might suffice. Norm ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Christopher Hicks" cmh21x~xxcam.ac.uk Date: Fri Jun 26, 2009 4:10 am ((PDT)) In MyMyfordx~xxyahoogroups.com, anthrhodesx~xx... wrote: > When using a 127 to convert from inch to metric pitch it is used in the driven position, for instance 100 driving 127. For the sake of convenience reverse the calculation and divide 127 by 100, result 1.27. But when using a 63 for the same conversion it's used as a driver. The closest equivalent to 127 / 100 is 80 / 63 = 1.26984. To determine the error by using a 63 in this way rather than the preferred 127 divide 1.27 / 1.26984 = 0.99988 or 1-1/4 parts in 10,000. < Right. I calculated the error introduced by the obvious substitution of (say) a 50:63 ratio in place of a 100:127 ratio. Given the set of gears available on a given day for a given machine it may be possible to come up with something better, and I agree that 63:80 is indeed substantially closer than 50:63. CH ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Dennis Jewitt" dennis.jewittx~xxtiscali.co.uk Date: Fri Jun 26, 2009 9:18 am ((PDT)) Ian. Didn´t the BSW head size change at some point? maybe during the war to save steel or for some other reason. I think I have a few spanners lying around that confirm this but will look later. Dennis ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Bob Minchin" bob.minchinx~xxntlworld.com bobdownfield1 Date: Fri Jun 26, 2009 12:09 pm ((PDT)) Dennis, You are correct about the headsizes. Ian wrote about in his reply as you will see further down this thread. Bob ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Norman Atkinson" ravensworth2674x~xxyahoo.co.uk Date: Fri Jun 26, 2009 1:08 pm ((PDT)) But Whitworth bolt heads were originally square not hexagonal. So, for that matter, were the French ones. Large square headed bolts were still being used in the Savoie as late as 1974-5 when Belles Challes in Les Arcs 1800 was being built. I think that the 'war' is an old wives' tale. What seems to have happened is that the Lords of Admiralty originally insisted on big bolt heads which the matelots could not twist off. Eventually, hexagon flats came into general use (giving more area for smaller spanners than hitherto.) What has to be remembered is that square nuts were blacksmith forged. Torque amongst yourselves, eh? Norm ------- Re: A breadcrumb trail through the thread/spanner forest? Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Fri Jun 26, 2009 2:05 pm ((PDT)) Gentlemen, the internet has a horrible habit of turning rumour into fact - I used the word "apparently" in my comment about the reason for the change in BSW bolt head sizes being due to the attempt to save metal during WWII - I have no evidence for this, but to quote the well known journalist's motto - "Don't let the truth get in the way of a good story". Ian ------- Screw cutting help needed [MyMyford] Posted by: "the_iliad26" stephen.white200x~xxntlworld.com Date: Mon Jul 6, 2009 10:05 pm ((PDT)) Very new to all this and i am trying slowly to learn how to use a lathe. I have a super 7 complete with quick change gear box. Is there and simple straightforward written instructions on how to cut threads using this box? I have read Martin Cleeves book on screw cutting and i am now just very confused as the he states in the book that he does not like the quick change gear box and the book does not deal with it. I have read the instructions for the gear box and can't figure that out either. I know of no one local to me who is interested in this type of thing to get any help or instruction from. Can some please help? ------- Re: Screw cutting help needed Posted by: "Bob Minchin" bob.minchinx~xxntlworld.com bobdownfield1 Date: Mon Jul 6, 2009 11:49 pm ((PDT)) If you have Cleeve's book on screwcutting then just consider the gearbox as an easy way of setting the gearing ratio between the mandrel and the leadscrew. Set the two levers to the row and column for the TPI needed AND reverse the gear behind the strap inside the end gear cover. You will also need a thread dial indicator -- a myford accessory that bolts on the right hand side of the saddle to show you when to engage the saddle feed. Don't forget that screwcutting is done at very low speeds with the backgear engaged -- see myford lathe manual for how to do that (in the files section of this group). If this does not answer your problem then come back with some more specific questions and we can try and help. Bob ------- Re: Screw cutting help needed Posted by: "tobybishopx~xxaol.com" tobybishopx~xxaol.com tsb2225 Date: Tue Jul 7, 2009 2:54 am ((PDT)) Hi Stephen. If you tell us roughly where you are in the world, you might find that someone is close enough to offer some direct assistance. I'm in Fareham, UK. I too have a S7 with gearbox and have not yet used it to screw cut but I'm about to cut a matching (hopefully) nut and thread on a large collet to hold a flywheel on an engine shaft. I'm aiming for 20TPI on 1.5" dia -- non standard I know, but it will meet my particular needs. My understanding is that you reverse the gear pair in the end cover -- the pair held in place by a strap which will swing up and over to release the gear. Take the pair off, turn over and replace. This switches you from the fine feeds on the gearbox to the Threads Per Inch range. Move the 2 levers on the gearbox to select the TPI you require -- you might need to turn the spindle by hand to ensure the gears will engage. Then you want to use the backgear to bring the speeds very low or even turn the spindle by hand with a handle on the headstock end. A threadcutting indicator will be useful but you can get by without it by hand winding the spindle backwards between cuts (having withdrawn the tool beforehand to preserve the tip). Have a look at: http://f1.grp.yahoofs.com/v1/cPJSSiGTg7UPJxctzMSEVfLzEp-7J4KJMI X5aZjwlv59VQSDs2HJCFnJQauccc-EC2PyCVoOMEu4TqUKckOgKgaRVL2B/Sup er%207%20Gearbox%20manual%20712V.pdf This is the QC Gearbox manual (I hope). Item 3 in Fig 7 on page pair 6-7 is the gear you need to turn over. The strap is just above the number 3. It swings up and away to the left allowing the gear to slide off its stud. Hope this isn't too confusing. cheers Toby ------- Re: Screw cutting help needed Posted by: "the_iliad26" stephen.white200x~xxntlworld.com the_iliad26 Date: Tue Jul 7, 2009 4:20 am ((PDT)) I have a thread dial indicator which was attached to my lathe when i bought it. My problem seems I am too dumb to operate it all. Is the larger number printed on the gear box the pitch of the required thread? ------- Re: Screw cutting help needed Posted by: "Bob Minchin" bob.minchinx~xxntlworld.com bobdownfield1 Date: Tue Jul 7, 2009 4:35 am ((PDT)) Not know how to do something is not being dumb. Asking questions and learning from the answer is the right thing to do. > Is the larger number printed on the gear box the pitch of the > required thread? Correct. With the gear one way round, you get the large number in TPI. Fit it the other way round you get the fine (r) feed express in thou per rev. Bob ------- Re: Screw cutting help needed Posted by: "the_iliad26" stephen.white200x~xxntlworld.com the_iliad26 Date: Tue Jul 7, 2009 5:51 am ((PDT)) Okay i know that the gear is in the fine feed position at this point in time. So i can change that and have a go at producing a thread. ------- Re: Screw cutting help needed Posted by: "Ken Strauss" ken.straussx~xxsympatico.ca kstrauss7 Date: Tue Jul 7, 2009 6:29 am ((PDT)) At the risk of further confusion I suggest that you ignore the threading dial and simply leave the half-nuts engaged at all times. It is one less thing to worry about and the threading dial is useless if you need to cut metric threads. Also, a hand crank will greatly reduce the drama of threading to a shoulder or internal threading to near the bottom of a hole. ------- Re: Screw cutting help needed Posted by: "bobdownfield1" bob.minchinx~xxntlworld.com bobdownfield1 Date: Sat Jul 11, 2009 1:47 pm ((PDT)) One tip Stephen is to make sure when you are starting out screwcutting is to make sure you have some decent free cutting steel. I find there is always a temptation to try things out on bits of scrap just lying around the workshop. There are enough things to concentrate on when taking those first few faltering steps in screwcutting without having to contend with a bit tough stringy old steel! Good Luck Bob ------- Tapping Guide [taigtools] Posted by: "John" johnsaundersx~xxpetruspartners.com Date: Mon Jul 20, 2009 6:43 am ((PDT)) After botching a part this weekend due to crooked a crooked tap, I need to buy/make a tapping guide. I'm looking for something modular (i.e. to use freehand instead of rigging up a tap & guide in my drill press or lathe). I saw the "Tapping Block" by OWM at LMS (part #2571. Link: http://tinyurl.com/lzxrsr which looks like it would fit the bill except for $40, why not just make it in-house? Am I missing some aspect to this part which makes it difficult to make/machine in the home shop? I see that it's out of 4140, which is tough, but still machinable... Thoughts? ------- Re: Tapping Guide Posted by: "rx~xxshred2.net" Date: Mon Jul 20, 2009 7:18 am ((PDT)) I just drill short stub ends of rod to make single-size tapping blocks. Others use bolts or fancier setups-- http://www.homemodelenginemachinist.com/index.php?topic=5406.msg56917 ------- Re: Tapping Guide Posted by: "wildhorsesoftware" gfbx~xxmypage.net Date: Mon Jul 20, 2009 7:30 am ((PDT)) Nothing against LMS, but why pay that kind of money for a block of metal with a few holes drilled in it. Grab a hunk of aluminum of the appropriate size and start drilling holes. I have a half dozen such blocks, all from aluminum. Unless you are going to be tapping one heck of a lot of holes (in which case you should consider a Tap-O-Matic) aluminum will work just fine. It doesn't matter what size the hunk of metal is so long as it is of a thickness appropriate to the length of the tap and has two faces that are parallel. Also have a look at Enco catalog page http://www.use-enco.com/CGI/INPDFF?PMPAGE=107&PARTPG=INLMK3&PMITEM=893-1274 I have several of what they call the Micro Tap Guide and use them for 70% of my non-production tapping jobs. I also have a Tap and Reamer Aligner (same page). Although pricey, they are great for use when you cannot easily get the piece on the table of a mill or drill. They also have a V-Slot for tapping into round objects. Another tool I use is http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=12387815&PM AKA=326-1568 I use a cheaper version, I think it came from LMS. I use this on a particular production job that does not lend itself well to my Tap-o-Matic. I paid around $70.00 for mine. I'm not thrilled with the "adapters" that came with mine, but they are easy to replicate. Point is, I would never spend $40.00 for a hunk of metal with a few holes drilled in it. If that is the tool you want, make it yourself. BTW, shop around before you buy anything. I like LMS but he tends to be a bit high priced on some items. Sears is a good place to do some comparison pricing. Regards, Gary ------- Re: Tapping Guide Posted by: "Stan Stocker" skstockerx~xxcomcast.net Date: Mon Jul 20, 2009 8:25 am ((PDT)) Hi John: Nothing to making these at all. The order of operations is: Make one face FLAT. Not to the micron, but really flat. This is your reference surface. OPTIONAL: Make the other face flat and parallel OR mark it "This Side Up". If you are going to stamp this into the metal, do it BEFORE final flattening of the reference face. The displaced metal will put some small but non zero bend on the material if it's fairly thin flat stock. Clamp the reference flat face down on the mill table using parallels, or whatever turns you on. The flat side should be parallel to the table, and the mill or drill press should be trammed pretty well. Drill the holes using the shortest bit you have that does the job. Plunging with an endmill to open up the hole is even better as endmills are stiffer than twist drills. As needed: Finish holes to size, either with reamers, or by drilling to final size. General note: While production blocks are either made from tougher material or are hardened, for the amount of use typically seen in a hobby or small shop just about anything from aluminum to drill rod is fine. If in ten years you find you have worn a hole oval make another. The material should be thin enough to allow a few turns of the tap to get the threading started, but not so thin that it allows the tap to wallow around. Fancy touch: After making a face flat, mark out the hole locations. Mill a V groove centered on the line of holes, and lap flat. Now you can guide a tap into round stock too :-) Cheers, Stan Stocker, Clockmaker Linden, Virginia ------- Re: Tapping Guide Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Date: Mon Jul 20, 2009 11:02 am ((PDT)) Since switching over to gun taps (that shoot the chip ahead of the tap) and form taps (that forge rather than cut the thread) I have cut down on tap breakage tremendously. Dull taps break. Hand taps need to be reversed every half to full revolution to break the chips. If the flutes clog up with chips then they'll break. Using proper lube is important as well. I use a Fisher tap guide on the big lathe, but most tapping is done by hand without any guide. See our homepage at www.cartertools.com/nfhome.html ------- Re: Tapping Guide Posted by: "Don Rogers" Donx~xxCampbell-Gemstones.com Date: Mon Jul 20, 2009 11:31 am ((PDT)) For what it's worth, when I'm tapping parts, I'll usually tap them on the drill press. I drill the hole, remove the drill and then chuck up the tap and tap the hole without moving the part. I tap by hand unless it is a through hole. I just hold slight down pressure and turn the spindle pulley by hand, being careful not to pinch yourself with the belt. When I have the tap to depth, I use the belt to back it out. For through tapping, you need a gun tap or spiral tap. Put a slight down pressure on the tap and blip the start switch. Once the tap is 1/4 way into the stock, I'll make another turn or two by hand to make sure the piece is fully threaded -- then use the belt and back it out. It's a bit of mucking around, but it gives you a straight tap, at least as straight as the drill press is to begin with. When tapping a turned piece on the lathe, I'll do the same, Drill the hole and then put the tap in the drill chuck and tap by hand. The tap guides like the one that has all the holes, is too big and cumbersome for small work. Tapping with the same setup you drilled with ensures that the tap is following the hole exactly. Last summer, a guy had a tap head for sale for $40. I picked it up and I've got to say, it is the best thing since sliced bread. IF, your drill press will handle it. My small drill press, the tight and accurate one is too short to handle the tap head. My bigger drill press has a wobbly spindle, and I won't use the head for any thing under a #10 tap, but man it is so easy to tap a hole with it. I need to get my spindle tightened up and then get my X-Y-Rotary table set up and give it a real work out. I need to build a screw plate for my mill anyway, and this way it would be very easy to get one done. Don ------- Re: Whitworth thread cutting [atlas_craftsman] Posted by: "Dragonflight" dragonflightx~xxrogers.com Date: Wed Aug 26, 2009 6:13 pm ((PDT)) I have a question - never really understood why the compound is set for 29 degrees for metric/UN threads instead of 30? Further would this not also apply to Whitworth threads? (ie 26.5 degrees?) As a note: In the Atlas lathe guide it says to cut the Whitworth thread as the ACME thread for which they use exactly half the angle implying that it should in fact be 27.5 degrees. As well they talk about the top and bottom of the thread being shaped correctly with a formed tool. Specifically with .1373xpitch radius and a thread depth of .64033xpitch. I imagine a vee bottom and flat top would work fine once you figured out the equivalent depth and outer diameter. mike ------- Re: Whitworth thread cutting Posted by: "Starlight Tool Services Ltd" starlight_toolsx~xxtelus.net Date: Wed Aug 26, 2009 6:39 pm ((PDT)) Mike: By setting the compound at 29.5 deg instead of 30, you are no longer cutting on both faces as you feed in, but only the leading face, so you get less chatter and a cleaner cut. If I were cutting Whitworth Thread, I would probably set the compound to 27 Deg, again 1/2 degree off the theoretical so that only the leading tip of the cutter would be engaging the cut. A sharp vee at the bottom of the thread is like putting a notch into it. A stress point where a crack can propogate, thus the recommended radiused bottom of the thread. Makes for a stronger overall thread. Walter ------- Re: Whitworth thread cutting Posted by: "Michael Schetterer" finegrainmetalx~xxhotmail.com Date: Wed Aug 26, 2009 6:58 pm ((PDT)) I will have to respectfully disagree. In truth, by moving 1/2 degree closer to straight in, you are actually ensuring that a light cut is made on the full extent of the trailing face with every pass. It might help to imagine what would happen if you took each case (underrotation and overrotation) to their extremes. In the extreme underrotated case, the advance is straight in, and both edges are taking equal, full-face cuts. In the extreme overrotated case, the trailing edge would be a shallow-sloped stairstep. The very front part of the trailing edge will be cutting, but the trailing edge will never have a chance to take a full-face forming cut. Regards. Mike ------- Re: Whitworth thread cutting Posted by: "Starlight Tool Services Ltd" starlight_toolsx~xxtelus.net Date: Wed Aug 26, 2009 7:24 pm ((PDT)) Mike: By setting the compound to 29 or 29.5 deg on a standard 60 degree thread form the main advantage is that it reduces the tendency for the part to push away because some of the cutting pressure is directed towards the spindle. See Machine Shop Trade Secrets page 180 section 6 on threading. This way the trailing edge of the cutter is yes, as you mention, just taking a fine chasing cut on the finished side of the thread while the cutting edge does most of the work of forming the thread. Again the main benefit is that you reduce chatter, deflection and get a cleaner cut. Walter ------- Re: Whitworth thread cutting Posted by: "jmartin957x~xxaol.com" Date: Wed Aug 26, 2009 7:36 pm ((PDT)) It has little to do with the part pushing away or with chatter. The main advantage is that it loads the carriage against the leadscrew. Cut straight in, with an equal chip coming off each side of the cutter, and there is nothing to keep the carriage from occasionally jumping ahead, then lagging, causing a drunken thread. With the chip coming off just the headstock side of the bit, the leadscrew has to constantly force the carriage along - and that is what gives you an even thread. John Martin ------- Re: Whitworth thread cutting Posted by: "Dragonflight" dragonflightx~xxrogers.com Date: Wed Aug 26, 2009 8:47 pm ((PDT)) I have to think there is more to this. By setting it to 29 instead of 30, each cut is less than 1/10 and more like 1/100 of a thou on the trailing edge. Whether it is 29 or 30, most of the force is directed at an angle to the headstock. In any case I don't know why it would be different for other threads, but I have read 29 degrees for metric/UN and exact angle for acme threads. Perhaps someone once made a mistake and said 29 and it's never been corrected since!!! (kinda like reading 50 references on the internet and then realizing it all only came from one source) To John Martin's point, I have found that I still need to apply pressure on the handwheel to make sure the early cuts don't skip and it seems to make the later ones cleaner. I have also cut threads head on ie compound at 90 degrees (favoured by some because you can finish the thread by moving sideways at the end and make a flat bottom in the thread -- luckily at 60 degrees you move the compound half the cross slide) and I seem to have the same trouble, same solution to it skipping threads, ie light back-pressure on the carriage handle. mike ------- Re: Whitworth thread cutting Posted by: "Starlight Tool Services Ltd" starlight_toolsx~xxtelus.net Date: Wed Aug 26, 2009 9:28 pm ((PDT)) MIke: An Acme thread cutter is a formed tool which results in a thread with a large flat bottom, a large flat top and steep 29 deg sides. If you offset the cutter it would not give you a proper cut. The steps to cut an Acme thread are almost the same as 60 Deg type threads but the compound rest is set at 0 deg and the compound is advanced after each cut, while the cross feed is returned to the same setting. Lighter cuts must be taken because the total cutting face of the tool is longer. For 60 deg threading I have seen references to both 29.5 and 29 degrees in different text books on turning; the main thing is to get most of the cutting forces towards the spindle and have only a light chasing cut on the trailing side of the cutter. Just watched the MIT video on threading and he uses 30 deg, but then he is also turning the threads on a Hardinge. Hope this helps Walter ------- Re: Whitworth thread cutting Posted by: "Michael Schetterer" finegrainmetalx~xxhotmail.com Date: Wed Aug 26, 2009 9:51 pm ((PDT)) Acme threads can be cut with the compound at anything between 0 and 14.5*, just like 60* threads can be cut at anything between 0 and 30*. The benefits of cutting 60* threads at 29* apply to cutting Acme at 13.5* (or 14* or 13*) -- most of the cutting happens at the leading edge so the leadscrew is consistently loaded, and the trailing edge is making a consistent full-face light cut to nicely define the trailing flanks. I realize there's a LOT of opinion on these details. My version of the truth is based on real-world thread-cutting. Maybe I'm just dumb-lucky, but it works for me -- 60* threads at ~29* and Acme at ~13*. If I were to do a Whitworth, I'd use 26*. YMMV and FWIW . Regards. Mike (S) ------- Re: Whitworth thread cutting Posted by: "Starlight Tool Services Ltd" starlight_toolsx~xxtelus.net Date: Wed Aug 26, 2009 9:59 pm ((PDT)) Michael: Fortunately I do not have to do much threading on the lathe. About 99% of my turning is trueing up armatures and you do not want a thread pattern there. When I do threading I have to get out the book and double check what I am doing, so generally I am following what my text books have set out for steps and angles. Walter ------- Re: Whitworth thread cutting Posted by: "Michael Schetterer" finegrainmetalx~xxhotmail.com Date: Thu Aug 27, 2009 7:20 am ((PDT)) I have done an occasional "straight on" and it works fine for small threads. I pretty much always have my compound set to 28-29* though so I'm usually all set up for threading even if I'm just doing regular cuts. On the Acme, I grind a form cutter that represents the entire threadform. Yes, each Acme thread has a different termination, but it's no big deal to bring the flat to size after I've got the sides ground to 29* included angle. Regards. Mike ------- Re: Whitworth thread cutting Posted by: "jo barden" jobarden422x~xxmsn.com Date: Thu Aug 27, 2009 8:08 am ((PDT)) I have recently made a false nose for my Drummond M type lathe which is a 1" 1/8 Whitworth form thread (so I can mount lathe chuck on rotary table); and not having a top slide to set the tool at 27 1/2 degrees, I cut it straight on, no problems, worked well, took about 4 cuts from start to finish at 10 thou (ish) a pass; take it easy, slow back gear, use a thread gauge so that the tool is correct to the work and away you go. good luck Jon ------- Re: Whitworth thread cutting Posted by: "catboat15x~xxaol.com" Date: Thu Aug 27, 2009 6:08 pm ((PDT)) As I remember without getting out the text books the Whitworth thread is 55 degrees, not 60 degrees. During World War 2 it was found much of the American stuff sent to England had American 60 degree threads and the British nuts would not fit. That was when both England and America came up with the "U" thread systems (UNF and UNC) for Unified National Fine and Unified National Coarse; and all threads according to that standard were 60 degree threads. I also think there was some compromise on the outside of nuts so "spanners" and "wrenches" would interchange as well. I can remember a project where I purchased some 1/4 inch by 20 TPI bolts and nuts at a local home center and when I got them home there was no way those nuts would fit the bolts. I tried to chase the threads on the bolts with a 1/4 X 20 die and split the die right in two. The Chinese are not too good on American threads. In the same light I purchased one of those Chinese mini mills and to horror and some ruined work I found the 1/1000 markings on the feed dials were on 16 TPI lead screws so there was an "odd" graduation at each revolution. I had to change out the lead screws and nuts to 20 TPI so the feeds came out correctly. (Replacement lead screws and nuts are available from "Micro Mart" if you have that same problem.) ------- Re: Whitworth thread cutting Posted by: "jerdalx~xxsbcglobal.net" Date: Thu Aug 27, 2009 9:33 pm ((PDT)) TCHarex~xxaol.com wrote: > You expected a Bridgeport for $425 dollars? Tom No price difference makes up for an actually non-functional item (except in the mind of a chinese manufacturer who may {with reason} consider us to be stupid)......... and a lower price should not be automatically assumed to have a fatal flaw.... unless far lower than correctly made items. It may, surely does, lack refinement, and accuracy, in comparison to a more expensive item. But there is no excuse for an item which is made as a "counterfeit", with dials that look right, but are actually wrong, as I have heard with respect to some items, perhaps including the mill in question. Particularly when similarly priced items with proper dials etc are available. JT ------- acme & square thrds ...one more way [atlas_craftsman] Posted by: "n8as1x~xxaol.com" Date: Thu Aug 27, 2009 3:15 pm ((PDT)) ..FWIW ....for me , always necessary on square thrds to get proper clearance & also on acme when trying for zero lash ........set compound at 90 deg to x slide ( in line w/ lathe center line.) use acmr thrd ga or specs from handbook to grind an UNDERSIZE bit w/ correct side angles & front flat ....now cut w/ crosslide to FULL depth ..use compound to take side cuts , couple thou at a time till desired fit ...this cleans things up nicely & allows a no slop fit w/ a worn or better yet skim cut screw , to size it true, whole length ,when single pointing a nut .....also when cutting a screw to a tandard nut , you are not bound by any discrepancies in the nut size ( manufacturing tolerances.)...........this is an " old brit" method used & shown to me by a canadian master machinist during an extended visit several years ago ... when cutting coarser thrds w/ crosslide only , i use a spring ( gooseneck ) holder for the thrds & thrds are clean on the late model craftsman 12x36 .....but w/ V thrds, i use the conpound set at 30 deg ,,,,,easier for me to figure depth of cut , & has worked well last 50 years.. i have cut coarse thrds w/ crosslide only on 1895 Reed 14 in.....using a spring tool holder , they are clean ..big problem w/out a compound is keeping track of where your last cut was after backing x slide off to return carriage....w/out a dial , u must chalk a mark or make a thrd stop ( which i did) ...PIA ........w/ a dial on crosslide, straight in cutting w/ a spring tool has worked well..... best wishes docn8as ------- Re: acme & square thrds ...one more way Posted by: "Robert Silas" robert.silasx~xxvideotron.ca Date: Thu Aug 27, 2009 3:33 pm ((PDT)) Forgive my ignorance, what does a "spring tool" look like?? Robert ------- Re: acme & square thrds ...one more way Posted by: "doc" n8as1x~xxaol.com Date: Thu Aug 27, 2009 6:27 pm ((PDT)) .gooseneck comes pretty close....start w/ Armstrong /williams parting tool holder BUT . instead of the slight rise at the bit clamp , the gooseneck goes straight up for maybe an inch , then curves to come back down & become horizontal & continue back like the ordinary parting tool holder.. there is an angled vertical slot of varying width separating the up/down loop .. this allows the tool bit to spring back when "overloaded " ., effectively reducing chatter & making a cleaner cut . there are variations & some are for a turning bit , some for a thrdng bit & some for cut off... some are adjustable for the amt of spring. & one shop made one I have is VERY flexible .w/ it , I can plunge cut a 60 deg point on a one inch bar w/ a flat full width 3/8 bit on my Reed at 145 rpm or on my crftsmn 12x36 at just under 100 ( back gear , cant remember xact speed, 3rd or 4th in back gear, abt 89 rpm ) I can watch the bit deflect as much as 1/16 in when pointing up & hitting a "hard place" or avoiding a chatter. On ebay these armstrong & Williams gooseneck parting tool holders have an S in front of the number like S-30, S 31, S-23. WILLARD also makes a gooseneck thrdng tool holder for cutoff & turning /thrdng bits.. these were mostly used on olde tyme lathes w/out compounds ( thrds were plunge cut ) , the lathes , made for carbon tooling , were still in use in 1920's... not beefed up for the then new hi speed tooling ( came out around 1905)......around the 1930's . lathes again began to be beefed up for the then new carbide tooling ......... My circa 1918 monarch 14 inch , built for hi speed weighs circa 2000#...... 14 inch monarchs made after WW2 for carbide tooling weigh 4000#+..... my 14 inch Reed , 1895 , weighs circa 1650 #, 15 inch Prentice bro. , 1890 , weighs a few hundred less..!!!!!!!!!......gooseneck tools allowed higher speed w/ out chatter , & cleaner thrds... & are an answer to the same wt. problems w/ atlas /crftsmn.... so hold on to your lantern tool post .. there are times when they are really needed ( tight places, special tools..) Best wishes Docn8as ------- Threading non-standard size - calculation [atlas_craftsman] Posted by: "hwandre" mandrex~xxen.com Date: Sat Sep 12, 2009 5:04 am ((PDT)) Hello all. Probably stupid question on something already covered many times, so forgive me but I can't find the darn thing! What I'd like to know is how one determines the inside diameter for perhaps a screw-on lid for non-standard threads. For example - suppose one makes a container with a 3" diameter and threads it 16 TPI - how do you determine the necessary ID of the proposed lid prior to doing the internal threading? The only thing I've found was one reference saying: the minor Ř = the major Ř minus double depth of the thread. Any help? Best, Mike ------- Re: Threading non-standard size - calculation Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Sat Sep 12, 2009 7:47 am ((PDT)) There's a whole section in _Machinery's Handbook_ dedicated to screw calculations. For something like that, you can use what you want and make the screw thread inside diameter the major diameter minus 1/TPI. So, for a 3" major diameter 16 TPI outside the inside diameter would be 3 minus 1/16 or 2.937". As long as you're making both parts as a one-off that will get you into the ballpark. Make one and then make the other to fit. ------- Re: Threading non-standard size - calculation Posted by: "hwandre" mandrex~xxen.com Date: Sat Sep 12, 2009 8:01 am ((PDT)) Hello Russ: Thanks for the response. It sounds a bit like the one I found but simpler. Yes, this would be 'one off' stuff and non-critical in any way - just messing around. I have Machinery's Handbook, 25th edition, and darn if I could find the calculations other than for standard sizes. Best, Mike ------- Re: Threading non-standard size - calculation Posted by: "William Rutiser" wruyahoo05x~xxcomcast.net Date: Sat Sep 12, 2009 8:31 am ((PDT)) In MH, 24th ed, the basic 60 degree thread form is shown in the diagram at the beginning of the section titled "Screw Thread Systems" at the "Threading" thumb tab. ------- Re: Threading non-standard size - calculation Posted by: "hwandre" mandrex~xxen.com hwandre Date: Sat Sep 12, 2009 3:36 pm ((PDT)) Bill: Thanks for the info Best Mike ------- Re: Threading non-standard size - calculation Posted by: "Russ Kepler" russx~xxkepler-eng.com Date: Sat Sep 12, 2009 9:21 am ((PDT)) The "nominal - thread_pitch" will give a hole that would give 75% of thread if tapped (plus or minus a bit). In metric threads that means that you subtract the pitch from the nominal size; in inch systems you subtract 1/tpi. > I have Machinery's Handbood, 25th edition, and darn if I could find the > calculations other than for standard sizes. The chart at the bottom of the page starting with "Screw Thread Systems" gives the information that you need. If you pick a common UN pitch, the chart about 6-8 pages later giving thread depth, etc. for UN pitches gives you the numbers you need without having to calculate them; you just need to apply them to your nominal dimensions. ------- Re: Threading non-standard size - calculation Posted by: "hwandre" mandrex~xxen.com Date: Sat Sep 12, 2009 12:19 pm ((PDT)) Hello Russ: Thanks for all the help - I'll give it a try (and I'll look at that darn MH again - too many pages and the print is too small!) Best, Mike ------- Re: Threading non-standard size - calculation Posted by: "azbruno" azbrunox~xxyahoo.com Date: Sat Sep 12, 2009 6:50 pm ((PDT)) Not a stupid question at all, Mike. I tend to cut a lot of non-standard threads and when I first started I spent a lot of time pondering over the MH and the math. How to determine the bore can depend on the amount of flat on the internal and external threads and the desired fit. Considering a standard 1/8 flat on an external thread and 1/4 flat on internal thread; the thread overlap is 5/8 times the thread depth, which is root 3 times half the pitch. Double that for the difference in diameter. So basically, take the square root of 3 divided by the TPI and multiply by .625. That's the amount to subtract from the external thread diameter to bore for the internal thread. For a 3"-16 TPI, the external is turned to 3.000" and internal is bored to... 3.000 - (square root(3) / 16 * .625), or 2.932". Now that implies a tight fit thread so you may want to loosen it up a bit. And don't forget to account for the sharpness of the tool when determining the thread depth you're cutting. Do one thread and then cut the other to fit. Bruno ------ Re: Threading non-standard size - calculation Posted by: "hwandre" mandrex~xxen.com Date: Sun Sep 13, 2009 2:17 am ((PDT)) Hello Bruno: Good to hear from you again! As usual, you always have the answer - thanks for sharing this. Best, Mike ------- coil winding and metric threads [atlas_craftsman] Posted by: "wgmna48" wgmna48x~xxyahoo.com Date: Sat Sep 12, 2009 11:45 pm ((PDT)) The lathe operation manual that came with my 12" QC lathe says that Clausing can provide gearing for thousands of coil and wire sizes; is this service still available? Question 2 is, if I wanted to run some metric threads, what gears and other parts would I need. Thanks for any help with my dumb questions. Had this thing for years and still need to learn more! Thanks, Bill ------- Re: coil winding and metric threads Posted by: "carvel webb" carvelwx~xxabsamail.co.za Date: Sun Sep 13, 2009 12:27 am ((PDT)) Hi Bill: The gears and the set up are described in the manual. Depending on which Metric threads you are looking for, it is easy to convert the QC lathe for 1mm, 1,25mm, and 1,5mm using just the 52T and 44T gears. I have described this in an article in the files section, and Lathes.co.uk have included it in the description of the QC box on their site. Kind Regards, Carvel ------- Re: coil winding and metric threads Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Sun Sep 13, 2009 12:28 am ((PDT)) The manual has metric gear setups. They all use a 56/44-tooth gear combinations. That gives a 1.2727 that is very close to the ideal 127 ratio. It will cut good enough threads. I have a near 3/4" long, 1.5mm pitch thread cut for a 50mm nut that works fine. Careful, the manual may be wrong on metric threads. Mine was all wrong. Even the updated table I found was wrong. When set to 1.5mm it cut a 3mm pitch. In the files area of the group are some updated thread tables. There is also a gear calculation program that you enter the gears you have and the desired standard or metric thread pitch. Works well but you may need to add idler gears. If you need to wind coils, you could figure the TPI needed and try the program. Scott G. Henion Stone Mountain, GA Consultant SHDesigns http://www.shdesigns.org ------- Re: Help with single point threading [SherlineCNC] Posted by: "imserv1" imservx~xxvectorcam.com Date: Mon Sep 14, 2009 5:47 am ((PDT)) In SherlineCNCx~xxyahoogroups.com, "tony_dspglobal" wrote: > Hi all, > I have a question regarding thread dimension charts. > Such charts usually give a max and min for the major diameter. > What dia. should I turn the blank prior to threading, > the max, min, or somewhere in between? Also, there are > 1A, 2A, and 3A specs. Which is the correct one to use > for general purpose threading? Once I start making the > thread, how do I know how deep to go? For most machine fastener applications, class 2 threads are the correct selection. Class 3 tend to be too tight and class 1 are too loose. Turn the OD to the size indicated in the thread tables in for example Machinery's Handbook. They provide a tolerance so that an acceptable threaded part can be produced and will always fit a nut made to the same specification. As long as your OD is within the spec, your thread will be OK. The depth of cut is the real problem. All the experts argue about how to do it and what size, and the direct answer does not lie in the table. In one of my former reincarnations I spent a lot of time creating a manufacturing cell with a precision CNC lathe as the focus. The criteria for operation of the work cell was that any setup could be done in less than 15 minutes, and the first piece had to be good. Setup included making the first part. Typical lot size per setup was 2-12 parts. Initially, first piece good on a threaded part was a challenge. When making OD threads, you do not measure the minor diameter. It is solely a function of your thread form clearance and has little to do with the function of the mating part. The critical items are thread form (there's a gage for that, looks like saw teeth), Major diameter (there's a gage for that-micrometer or caliper), and pitch diameter (there's a gage for that thread wires or thread mics). Hopefully you have recognized a pattern, that the only way to make an interhangable thread is to correctly gage its size. Inch unit, Unified threads (UNF UNC, etc) like 1/4-20, 8-32, etc have a small flat between the threads and a small flat at the bottom of the "V". The tools available to cut single-point turned threads may be pointed, flatted, or more likely radiused. The combination of the tool geometry and the thread specification will determine the actual total depth of cut. In all cases, the pitch diameter controls the fit. Depending on your controller, you can turn a thread, measure it (pitch diameter of course), adjust your tool offset (in X-diameter), and then recut the same thread with a slightly deeper cut. With our servo systems using DeskCNC, we cut an initial pass, measure the pitch diameter, and then simply flip the servo reset switch to make a small size adjustment on the Handwheel. If the adjustment is less than .002, I usually change the X coordinate in the controller which has the same effect. Move the tool to 1.0000 inch, change the X coordinate to 1.0020. Re-run the program and the next pass will remove .002 on the diameter. Fred Smith - IMService http://www.imsrv.com ------- Re: Help with single point threading Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Mon Sep 14, 2009 9:50 am ((PDT)) Hi, the best way to control and measure a thread is using a go-no go thread gage. However, for hobbyists or less than production that will prove pricey. So, the next best way is to use the 3 wire method. Jerry G (Glickstein) ------- screw cutting [myfordlathes] [new group at Yahoo] Posted by: "andyevans_2000" andyevans_2000x~xxyahoo.ie Date: Mon Oct 5, 2009 3:58 pm ((PDT)) Hello All - I am trying to cut a 5/8 BSF thread and need some help as i am new when it comes to screw cutting in the lathe. I have my topslide set over 27.5 degrees and have a 55 degree cutting tool (no radius) at center height. I am cutting 14 threads per inch. Everything seems to go fine, feeding in with the topslide by about 5 thou each time - i reach full thread depth and then do another pass without moving the slides - still more metal is removed, another pass and still more metal removal all from the leading edge of the tool cutting the thread away. Not sure if this is down to play somewhere? The result is that i cannot screw on a nut. Can anyone help - should i chamfer the screw ends, if so at what angle? Do i need to round off the crests and troughs of the threads or can i leave them angular? Would really appreciate any help as it is driving me up the wall. Cheers Andy ------- Re: screw cutting Posted by: "John" johnx~xxstevenson-engineers.co.uk Date: Mon Oct 5, 2009 4:28 pm ((PDT)) Andy, taking metal off on the last cuts is normal; it's what is known as 'spring passes' where the spring is coming out of the work. You normally allow for this so the last 3 or 4 spring passes leave you at the finished size. If you had taken too much off then the nut should fall on. Three main reasons it hasn't: [1] Burrs at the start as you have noticed, any chamfer, any radius will do, you need to break the sharp edges. [2] Not going to full depth, hard to determine this for a newbie, one way are thread wires that you drop in the vee's, two one side and one the other so you can mike over them and compare them to a table. [3] Crest radii fouling the base of the nut threads, a vigorous application of emery cloth will reduce the rough edges and round off some of the sharp corners, or light application of a smooth file. In industry they use what is known as full form inserts where it has one tooth and two finished crests, one either side so it forms a correct thread; the only problem is they are expensive and you need one insert per pitch. This is a poor man's version: http://www.stevenson-engineers.co.uk/files/screwcut1.jpg One piece out of a Coventry die head set will form a perfect pitch, root, and crests. They are found for a pittance at car boot sales, especially if one is missing or chipped and any pitch will cut any thread of the same pitch; diameter doesn't matter. John S. ------- Re: screw cutting Posted by: "andyevans_2000" andyevans_2000x~xxyahoo.ie Date: Mon Oct 5, 2009 11:59 pm ((PDT)) thanks very much John - i will try again this evening ------- Re: screw cutting Posted by: "durnfjmx~xxaol.com" Date: Tue Oct 6, 2009 1:38 am ((PDT)) I find it best to cut the thread almost to size using a single pointed tool, then use the full form tool just for the last couple of passes. It needs to be aligned very carefully with the thread you have already cut. Use cutting oil, and clean the crests of the thread as John suggests with emery. Even a vigorous application of a wire brush while the lathe is turning slowly can help remove burrs from within the thread. As well as Coventry die heads, you can use a tap of the appropriate pitch and profile; you will need to attack it with a grinder, and fabricate some sort of holder. If you have a die or die nut, of course that will clean up the cut thread perfectly. They appear very regularly at car boot sales, especially in BSF and BSW sizes. If all else fails, try cutting the thread on a bar that starts off (say) 10 or 20 thou undersize; if that fits the nut, at least it would tell you that you are cutting the correct pitch and angle. Or if you are using steel now, you could try cutting the thread on brass or something easier to cut -- that might confirm your?technique. The Myford is not a very stiff machine by industrial standards, and many tricks have to be learned to overcome that problem -- most of those come from experience and practice, so don't give up! Let us know how you get on. MikeD Off into the shed now to experiment with rotary broaching! ------- Re: screw cutting Posted by: "andyevans_2000" andyevans_2000x~xxyahoo.ie Date: Tue Oct 6, 2009 4:22 am ((PDT)) Thanks Mike ------- Re: screw cutting Posted by: "moyes_a" admx~xxamoyes.fsbusiness.co.uk Date: Tue Oct 6, 2009 3:21 pm ((PDT)) Hi Andy, It sounds like the same problem I had when I started model engineering 40 years ago. My bible was L.H. Sparey's brilliant book 'The Amateur's Lathe' which didn't mention this problem. I (and surely 99% of all model engineers?) don't have thread chasers to give the correct rounded crest. The problem is that if you don't round off the crest, the metal you haven't removed prevents the nut spinning on. The temptation is to carry on removing more metal from the flanks until you have a pointed thread which allows the nut to fit but still doesn't touch on the flanks. The answer is to turn off the crest before you start screwcutting. It's perfectly OK to do this, in fact metric threads are specified that way. The amount to turn off radially is, in nice easy numbers, 0.1/tpi So in your example of a 5/8 inch BSP thread of 14 tpi, you turn the stock to 0.625 inch then advance the tool to turn off another 0.007 inch. Then screwcut the thread. Incidentally, the amount of infeed of the screwcutting tool is 0.7/tpi which in your case is 0.050 inch (multiply by 1.127 if you have set the topslide over by 27.5 degrees). It's easy to memorise these two formulae and with them cut any Whitworth form thread (BSF, ME etc) without reference to table if you know the tpi and have a simple calculator to hand. This method might be used by others but I haven't seen it in print myself. Give it a try and let me know how you get on. Andrew ------- Re: screw cutting Posted by: "durnfjmx~xxaol.com" Date: Tue Oct 6, 2009 3:54 pm ((PDT)) I must get around to obtaining Sparey's book - so many recommend it! Good to see some numbers put to what I've been doing by intuition. Thread chasers are easily made from old or broken taps of the correct pitch and angle with just a little (lot of) grinding with an angle grinder or offhand - if you don't have the right one in your "odds and ends" box, have a look in the car boot sale, there are usually boxes of 'em - and while writing this I think, ? bet you could make a holder to use a "good" tap without destroying it - I'll have a look at that idea tomorrow - if it's possible, there's no doubt someone wrote it up somewhere before the Boer war . . . never mind, that sort of experiment is probably quicker, and certainly more fun than,?academic?research. Nos da, MikeD ------- Re: screw cutting Posted by: "Ian" forumsx~xxzitnet.co.uk Date: Thu Oct 8, 2009 7:40 am ((PDT)) Mike, I read somewhere recently about using a tap as a "chaser" for finishing an internal thread. I have a couple of questions though. 1 - Am I right in assuming that for an internal thread you would mount it along the axis of the lathe as you would a boring bar? 2 - Do you let the partly formed thread "pull" it in or use the power feed with the appropriate TPI feed rate? 3 - How do you set it up for external threads? Thanks Z ------- Re: screw cutting Posted by: "Robert" bob.minchinx~xxntlworld.com Date: Thu Oct 8, 2009 8:12 am ((PDT)) Yes, set up as for boring bar with power feed. Use the topslide to align the tap and the part formed thread. External threads need the lathe running in reverse and the tap cutting edge set up facing downwards. Less easy to put on the cut at each pass when doing external threads but doable. Bob ------- Re: screw cutting Posted by: "durnfjmx~xxaol.com" Date: Thu Oct 8, 2009 11:25 am ((PDT)) OK, but - using a tap for internal threads in this way presupposes that the thread you are cutting is quite a bit (someone'll tell us just how much) bigger than the tap, and there is sufficient depth in the hole - etc, etc. If you are prepared to take a disk cutter to the tap, and separate one of the flutes from the rest of the tap, you can then mount this in a appropriate holders for either internal or external thread chasing (running the lathe the "right" way and so on.) Start with a broken/damaged tap of the right pitch/angle - there's usually 4 or 5 or more good teeth left on at least one of the flutes, or a find a "car-boot" bargain tap - there's usually plenty around ready for salvage - especially in the older standards (BSW, BSF, NPT etc) My local BOC Gas and Gear shop sells 0.8mm thick 4 1/2" discs for the angle grinder, and these make cutting bits of HSS tools dead easy - do it outside the shop on a nice day, to save the getting grinding effluent on the machine slides.? The thread (in or ex - ternal) should be cut to nearly the right size in the conventional way using a single point tool, and the chaser used to finish the teeth to the correct profile - using the power feed, having first carefully aligned the chaser with the newly cut teeth by means of the compound slide. (and . . .Glad we now have at least 3 convertees to rotary broaching . . . anyone else experimenting?) Stay safe, MikeD ------- Re: screw cutting Posted by: "Ian" forumsx~xxzitnet.co.uk Date: Fri Oct 9, 2009 1:08 am ((PDT)) Thanks for the info, Now I have finished the rotary broaching experiments and once I finish the next two projects (Starting rollers and grinding rest) I will explore this idea further. Cheers Z ------- Re: screw cutting Posted by: "G Bennett" gbennettx~xxshaw.ca Date: Sat Oct 10, 2009 11:09 pm ((PDT)) There is an article in this month's (October 2009) MEW by Harold Hall that describes the use of a tap for internal threads with description and pictures of the setup. ------- Using Dies [myfordlathes] Posted by: "alan4227" a.j.moorex~xxbtinternet.com Date: Tue Oct 6, 2009 2:35 am ((PDT)) This is probably a really dumb question and I'm embarrassed to ask it, but here goes. Do other people have the same difficulty I have in starting a die to tap an external thread? Once I get above M6 or 1/4 inch, I struggle to get the die to bite and start cutting, rather than just chewing up the end of the shaft. I now make the shaft extra long, so that I can turn a long taper on the end and part it off after threading. And I apply the die with plenty of pressure, but still I have trouble getting it started cleanly. There doesn't seem to be the die equivalent of the 1st, 2nd and finish taps (or if there is I haven't heard of it). I know that if you have split dies you can open them up a little bit for the first cut, but not many dies on sale now seem to be the split ones, and in any case the range of adjustment available on them is very small. What do other people do? Regards, Alan ------- Re: Using Dies Posted by: "tsb2225" tobybishopx~xxaol.com Date: Tue Oct 6, 2009 2:46 am ((PDT)) Hi Alan: With dies I don't have too much difficulty - it's good to have a short tapered section to start the die. If I can, I'll start off in the lathe (not powered) with the tailstock barrel providing some pressure to keep the die and holder square. Is it possible that your dies are blunt? I had trouble with a tap recently whilst making some T nuts for my Dore Westbury mill. One flute of the tap started to chip on the rear edge (not the cutting face) and then I couldn't back it out of the hole or advance it (chip build up). The tap became totally stuck and I ended up knowing it would break off. Fortunately I'd already got enough nuts done. Any one else had this and found a solution? cheers Toby ------- Re: Using Dies Posted by: "mike.crossfield" mike.crossfieldx~xxvirgin.net Date: Tue Oct 6, 2009 4:10 am ((PDT)) Alan: I have similar problems on larger diameters, particularly if the thread is coarse. Like you, I put a taper on the end of the bar if I'm cutting the thread entirely with a die. However, where I can, I rough out the thread with a few passes of a single point tool in the lathe, and then finish it to size with the die. Mike ------- Re: Using Dies Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk Date: Tue Oct 6, 2009 4:23 am ((PDT)) I find it varies considerably with the quality of the die. The tailstock ram trick helps a lot -- my lathe has an inverter drive with a "jog" setting -- the lathe runs at slow speed but only while you hold down the green button -- and I often use this to start the die cutting. If the die holder has long enough arms, the nearest arm locks against the corner of the lathe bed and obviates the need for 3 hands...a bit crude, but it works if you take care. I find with larger/coarser threads, the problem is more often the material slipping in the chuck, and/or the belts slipping, rather than getting the cut started. The better solution is to rough out with a screwcutting setup and then clean up for accurate thread form with the die (or as John suggested, with a Coventry die insert). Regards, Tony ------- Re: Using Dies Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk Date: Tue Oct 6, 2009 5:37 am ((PDT)) Hi Alan, When you say "not many dies .... seem to be split etc", are you thinking the taps and dies you bought at a car accessory shop or flea market are the real thing? Scr**fix purchasers take note! If you want a die to work (at all) you have get one of a known good quality, the difference between a good one and a bad one is broadly comparable with chalk and cheese. As a general rule of thumb, non split dies are best only used to clean up an existing thread not create a new one, there are exceptions but let's not muddy the waters too soon. cj(UK) ------- Re: Using Dies Posted by: "myford7x~xxymail.com" Date: Tue Oct 6, 2009 12:23 pm ((PDT)) >As a general rule of thumb, non split dies are best only used to clean up an existing thread not create a new one, there are exceptions but let's not muddy the waters too soon.< Yeah what he said -- and the other guys -- and this -- 1-- there's an entry side on each die - the other side has a steeper chamfer for running a thread up to a shoulder -- make sure you use the entry side. 2-- I made a die holder to slide on the tailstock barrel. When I can't get the job in the lathe I use the same holder assbackwards with a guide bushing in the part which slid on the barrel. The hole in the bushing lines up the die with the rod. I used to chip teeth on dies before, especially on stainless steel, but this made everything go real good and the threads start easily every time. 3-- I had the same troubles like you said with this holder until I realised I should have made the hole for the die bigger. I just made it one inch for a one inch die. It needs to be like 2 percent bigger so you can expand the die enough. I reckon lots of home shop guys might not realise this. ------- screwcutting - fallen at the first hurdle. [MyMyford] Posted by: "nick" hierophylusx~xxyahoo.co.uk hierophylus Date: Wed Oct 28, 2009 4:44 pm ((PDT)) I am very new to this and would like to ask a bit of advice so all the smarties waiting to show how clever they are - please keep your clever comments for your mates, as they put a lot of people like me off posting here. I am trying to teach myself screwcutting on a super 7. The problem is that despite using the thread indicator my cutting tool is not following the original cut on the second pass. I suspect the gearing set up. Am in back gear I think and slowest speed. This is the gear arrangement http://www.flickr.com/photos/eldooderino/4053574267/ Not sure what is going here with the set up, - I haven't changed it since I bought the lathe. I would like to get back to 8tpi as I might stand a chance of knowing what I am doing. Despite reading some books (Ian Bradley, sparey) they are all not good at explaining the gearing set ups. (Why can't the change wheels have the number of teeth stamped on them ??) I can see in the charts I need a 20 tooth driver and a ? 75 idle wheel - don't know how to achieve it. ------- Re: screwcutting - fallen at the first hurdle. Posted by: "redpiperbob" robert_sims_3451x~xxyahoo.co.uk Date: Wed Oct 28, 2009 11:34 pm ((PDT)) Hi Nick. If you look at the picture on page 104 of Ian Bradley's Myford book. to get 8 TPI the following set up is needed. The outer gear on (4) in the pic should be 20t then the gear on the back (or the closest to the lathe mandrel) of (5) should be 75t then the gear on the lead screw (8) should be 20t. I hope this helps. PS most of my gears have the number of teeth punched on to them, the ones which don't I have used an engraver to scribe the number into the rim of each gear. Bob ------- Re: screwcutting - fallen at the first hurdle. Posted by: "ravensworth2674" ravensworth2674x~xxyahoo.co.uk Date: Thu Oct 29, 2009 12:44 am ((PDT)) Nick, I would agree that neither writer really covers the subject. In whatever opinion you regard my contributions, I would recommend Martin Cleeve for 'gearing' in his Screwcutting in the Lathe and George Thomas in the Model Engineers Workshop Manual for an explanation of several systems to try. At further risk of 'nasties', I think that you are going too fast to really see what you are doing (right or wrong), you could follow through with a GHT Mandrel Handle to slowly find out. Smart arse-ing further, have you thought that you are already expert in screwcutting? If you have power fed in surfacing -- and you have got it right, you've done it already. If you look at your work with a glass, you will see that you have created tiny threads. I hope that these few words will encourage you. Norman ------- Re: screwcutting - fallen at the first hurdle. Posted by: "nick" hierophylusx~xxyahoo.co.uk hierophylus Date: Thu Oct 29, 2009 2:12 pm ((PDT)) Hi Bob, thanks for the advice. I saw some similar that was just as welcome from Norman which seems to have disappeared (just after i ordered the Gleeve book.) I am now in the queasily familar situation of having taken everything apart and am unable to reasssemble either the way I want it or the way it was. My gears are in this pic http://farm3.static.flickr.com/2464/4055988167_f772699190_b.jpg I seem to have the right gears - 2 x 20 teeth and a 75. I have some problems tho. The 20 to go on the arm nearest the mandrel doesn't contact the ?tufnol gears and it is a loose fit on the spindle. None of the etxra bits seem to be ble to make a decent fit on the spindle. The gear at the extreme left which is made up of 2 gears that I can't separate is a 30 and a ?60. This is what came off said spindle and makes nice contact with tufnol. Hmmm. ------- Re: screwcutting - fallen at the first hurdle. Posted by: "ravensworth2674" ravensworth2674x~xxyahoo.co.uk Date: Thu Oct 29, 2009 3:04 pm ((PDT)) Nick, Sorry but I deliberately 'deleted' for the following reasons:- 1. I was worried about you stripping the gears at 8TPI. It's too coarse to experiment with. I suggested that you used a Mandrel handle (ouch!) There are 2 places that I can recall. One is the Heapy site and the other is GHT's MEWM. 2. I thought that 'Cleeve' set the job out properly. A lot of reading to be sure, but well written. When you get Cleeve, you will still have it by your side (when I have gawn a long time before). There is lots of practical 'other stuff'to add to your growing fund of knowledge. 3 I'd get friend Geo. Thomas. You will find that it may be heavy going at times but you'll make a lot of simple tools first -- and flushed with success -- go on to greater things. Somewhere (not here) I was prattling about parting off. I cannot recall when I made the thing (the Coronation of Queen Victoria, perhaps) but GHT described all these vee this and that so the metal would curl and that. Yea, got me the tools but for kicks, I made a plain one. No bells and whistles -- parted off 1" round with lashings of lard oil. You get the drift (of other chips). 4. Then back to topic and I wondered whether you had the stuff on your lathe to pin gears and to let them freewheel on short stubs. You know, Nick, it's dead easy when you've done it so many times but the guy that you are trying to advise hasn't. So you know some of the reasons for the backing off. It's not easy doing a 'correspondence course'. My apologies- please accept them Norman ------- [OT] 3/16"-40 tap [sherline] Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Mon Dec 21, 2009 7:45 am ((PST)) I know I've seen this subject here before...but Where can I find a 3/16"-40 tap? If the response is McMaster Carr, please be specific. It may be there amongst the 10 zillion taps they carry, but it has eluded me. Dick ------- Re: [OT] 3/16"-40 tap [sherline] Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Mon Dec 21, 2009 1:12 pm ((PST)) In the steam modeling world, there are 3 common threads... 3/16X40 1/4X40 5/16X32 PM Research does have a supply of both tap and die for each of the above. While you are ordering from PM Research, you can also order the brass steam piping and valves too. http://www.pmresearchinc.com/store/home.php Dan ------- Re: [OT] 3/16"-40 tap Posted by: "fpres61" fpres61x~xxyahoo.com Date: Tue Dec 22, 2009 8:32 am ((PST)) Hello everyone, Looking at the PM Research site, 3/16-40 is a model engineering tapered pipe thread and not a standard straight thread. Happy holidays, Frank Presley ------- Re: [OT] 3/16"-40 tap Posted by: "ransome michasiow" ransome_dukex~xxyahoo.com Date: Tue Dec 22, 2009 9:25 am ((PST)) Coles has them, see site for pricing. Ransome ------- Re: [OT] 3/16"-40 tap Posted by: "Steve Davis" sdavisps4x~xxyahoo.com Date: Tue Dec 22, 2009 1:12 pm ((PST)) Try Rutland tool or Travers Tool. I buy fine thread taps and dies from them all the time. Usually cheaper than McMaster Carr. Request their huge free cat. They have no broblem with small orders. Steve ------- Re: 3/16"-40 tap Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Wed Dec 23, 2009 8:25 am ((PST)) Thanks for everyone's input. I really thought this might be simpler, but.. PM research has a straight and a tapered 3/16"-40 tap. The straight is $6 and the tapered is $30.50. Almost certainly through the nature of things the callout is for the tapered one. The drawing calls out a '5/32 drill (1/4" deep tap to 3/16") for model pipe fittings.' I always did hate plumbing. Dick ------- Re: 3/16"-40 tap Posted by: "Alan Marconett" KM6VVx~xxSBCglobal.net Date: Wed Dec 23, 2009 9:55 am ((PST)) If the tap is a dead-end into a steam chest, you almost always need a taper to get started, and a plug to finish off the threads. I think my Stuart has a 1/4-40 (?) for that threaded hole. Hard to start (use a tapping fixture or the mill to get the taps started). I don't remember the threaded taps being THAT much! Even ordering from England. Try MMM? Alan KM6VV ------- Re: Threading on the lathe... [SherlineCNC] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Thu Dec 24, 2009 2:40 am ((PST)) Here's another idea: do your CNC thread turning on the 4 axis milling machine. Mount the Rotary Table on the mill bed with its axis horizontal, parallel to the X axis. Mount the work in a chuck on the RT. Remove the headstock, and mount a single point thread cutting tool on the Z axis -- maybe bolt a lathe tool holder to a headstock spacer. The Y axis feeds the tool into the work, the X axis feeds the tool the length of the thread, while the A axis turns the work. This seems like way too much fun not to have. I'll see if I can cobble something together and post a photo. BTW, the milling machine can be used as a lathe for turning as well. Rotate the head horizontal, put the work in a chuck on the head, and mount the cutting tool on the mill table. DC ------- Re: Hello!; going to take a look at a Mk. 2 lathe [atlas618lathe] Posted by: "John Bump" johnbumpx~xxgmail.com Date: Sun Dec 27, 2009 9:40 am ((PST)) >Today I've been experimenting with the gears for cutting threads. >Thread cutting takes coordination and quick reflexes if you have >the thing turning mok-5 (that sucker is quick!) I guess slow is the >way to go when cutting threads.... I built a crank, with a rotating handle and a bore like a bicycle stem, that fits into the headstock on the gearing end so I can turn the spindle by hand when cutting threads. It's an *enormous* help because all the stuff I've been doing lately involves turning up to a shoulder and even in the lowest gear that's still far too much excitement. If you try this, be warned in advance that you can't have the crank offset at 90 degrees because it'll interfere with the gears. >I have "engineered" a motor pulley and belt arrangement until I can get >the material to turn a motor pulley to "specs" and get a new belt... >I wonder, where is a likely place to find a piece of round alumininum bar >about 3" in diameter for the pulley? Maybe cut it out of a piece of 1/2" thick plate, 3" on a side? ------- cutting threads Posted by: "n1ltv" n1ltvx~xxyahoo.com Date: Sun Dec 27, 2009 11:03 am ((PST)) John: Have you seen the stem-style spindle crank under "Bruno's Lathe"? > >I wonder, where is a likely place to find a piece of round > >alumininum bar about 3" in diameter for the pulley? > Maybe cut it out of a piece of 1/2" thick plate, 3" on a side? I guess it would need more than one such plate but those could be neatly bolted together. One advantage of bolted sections is that the smaller diameter grooves could be turned from pieces already rough cut smaller than the 3 inch max. diameter, rather than having to turn off all that extra material on the lathe. Hank ------- Re: Hello!; going to take a look at a Mk. 2 lathe Posted by: "Uldis Stulpins" u_stulpinsx~xxyahoo.com Date: Sun Dec 27, 2009 2:28 pm ((PST)) If you need to cut threads up to a shoulder, it may help to undercut the shaft down to the thread root diameter (with a square-nosed cut-off bit) to provide a groove next to the shoulder whose dimension is wide enough to provide a "safe zone" where you can disengage the feed and let the shaft turn without the bit being engaged with the material. It also provides a starting place for when you're doing left-hand threads. The last 1 or 2 threads next to a shoulder usually don't much enter into the final picture anyway, except to sometimes cause problems with the female thread bottoming out on them before the shoulder is contacted, if those last threads are incomplete or buggered up at all. For expediency's sake, and if the threads don't have to be 100% concentric with the material's axis, there's also the use of an axial-style, round die holder (from Enco, etc. for a few dollars) held in the tailstock and turning the chuck by hand with a tommy bar (or, as has just been suggested, a crank attached to the spindle) while feeding the tailstock in or out with the right hand. Standard dies up to 1/2" thread size are cheap, much quicker to set up and use, and will always give predictable results, but you need to concentrate on the "feel" through both hands to avoid trouble. An undercut next to any shoulder will be helpful with this technique also. Naturally, YOU WILL HAVE DISCONNECTED ALL POWER TO YOUR LATHE using this technique. The same proceedure also works for larger thread diameters. (I've used it for 3/4" thread on steel with a handle-style die holder simply pinched between the tailstock and material to be threaded.) The handle is blocked from rotating by the top of the carriage or a block of wood placed across the ways, but needs room to feed itself forward as the thread cutting proceeds. The success is dependent on a few variables that determine if the die holder is perpendicular to the spindle axis when you start cutting and to your ability to manually apply torque to the chuck (or spindle), since the chip you're cutting with a die can get big pretty quickly with larger thread sizes. (I think that's why plumbers use that machine.) Also, you want to avoid permanently jamming the chuck onto the spindle nose, if you're applying torque to the spindle itself. That's why I use a tommy bar in the key holes around the perimeter of the chuck, to which I apply torque directly. The worst that will happen then is that the material may spin in the jaws if the chips jam things up. The die holder here is also fed forward with the right hand advancing the tailstock spindle, or withdrawing, as you break the chip free to make another cut. With either of these techniques, the chip cutting is not continuous, as it would be under lathe power, but similar to hand threading where you turn the die a portion of a turn and then back off, to clear the chip. But you can install much greater accuracy (concentricity) to your thread than you can with the material held in a vice and you holding the die holder in "free air". Here, the die is kept from rotating, but can advance forward, while the material rotates. Uldis ------- Re: cutting threads Posted by: "Leo Reed" lpreedzonex~xxearthlink.net Date: Sun Dec 27, 2009 4:40 pm ((PST)) I used the "hand crank" method to cut 1 x 8 threads, the same as on the spindle nose. Takes a lot of "crank power", but you have very fine control of the cut. (The threads are in aluminum parts, in steel it would be a problem.) Leo (pearland, tx) ------- LH Internal thread cutting [sherline] Posted by: "Jerry Jankura" toolzngluex~xxsbcglobal.net Date: Fri Jan 1, 2010 9:22 am ((PST)) Hi, Folks: With all of the traffic concerning threading & taps, I'm curious about how I'd go about cutting the left hand 3/8 x 20 thread to make one of those delrin/nylon saddle nuts to minimize backlash on my leadscrews. I've yet to find a specialty tap that will cut 3/8-20 as a left-handed internal thread. Jerry Jankura ------- Re: LH Internal thread cutting Posted by: "Thayer Syme" thayerx~xxgryffinaero.com Date: Fri Jan 1, 2010 10:07 am ((PST)) Can you make a tap from a section of lead screw? ------- Re: LH Internal thread cutting Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Fri Jan 1, 2010 10:50 am ((PST)) Yep! Case harden it with Kasenit. However, Delrin likes dead sharp tools. So, hone/grind those cutting edges in. Jerry G (Glickstein) ------- Re: LH Internal thread cutting Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Fri Jan 1, 2010 12:36 pm ((PST)) The Sherline thread cutting attachment will cut both RH and LH threads. Dick ------- Re: LH Internal thread cutting Posted by: "Marcus" marcusx~xximplant-mechanix.com Date: Fri Jan 1, 2010 1:31 pm ((PST)) Hi Jerry: The suggestion to use a section of leadscrew as an impromptu tap is a workable one but it's also worthwhile to precut the thread as close as possible by single point threading beforehand. The hardest part is making the threading bar...a workable way is to prowl through your worn out tap collection and grab one that's about the same TPI count but smaller in diameter, then grind away all of the threads but one on the flute you intend to use for threading. This gives you the proper threadform without having to make it yourself, and it can be done on an ordinary bench grinder. In your case a 1/4: 20 tap will be just the ticket...even better if it happens to be a left hand tap, but if not, then get out your Dremel and relieve the sides of the point you'll use without nicking the cutting edges. Magnification helps a lot for this. Practice a bit on other areas of the tap before you grind the remaining points away, and pick the best one as your keeper. You're only cutting Delrin, so exaggerated clearance angles will be of no consequence. Set up the gears with the proper pitch and left hand cut according to the Sherline chart and then mount your tool and determine which way you have to rotate the workpiece to make the cutter cut. The direction it runs (toward or away from the headstock) will be determined by the gear setup, and doesn't matter...you just want to turn the workpiece so the cutter is cutting and not rubbing. Keep nibbling the thread out in small increments until you're close. Now take your bit of leadscrew and put a 10 degree taper on the last 4 threads or so. Cut two gashes at about 180 degrees to each other with a file and then mark the cutting edges with a Sharpie. File a bit of relief on each taper until you just kiss the cutting edges on each side. Make sure you do this in the proper direction for LH taps...grab another tap (any old tap...you're just going to look at it for reference) and put it on the bench beside you so you don't get it backward and to get the proportions of your gashes about right. Now take a bit of hardened steel like a milling cutter shank and stroke over the faces of the gashes just a bit to displace the metal outward a hair. (Those of you who are woodworkers will recognize this technique... it's used to sharpen scrapers.) This will create a tiny bit of clearance for the thread. Don't overdo it...one light stroke is usually all you need, and if you're too timid the first time you can always raise the bur again. Don't harden it...just run it through the workpiece with a bit of Vaseline and then check the fit. If it's too tight, stroke the edges again and run through again. When it feels right, you're done. Cheers Marcus http://implant-mechanix.com/splash.html ------- Re: LH Internal thread cutting Posted by: "buckeyevs" buckeyevsx~xxyahoo.com Date: Sat Jan 2, 2010 11:42 am ((PST)) I made a 3/8-20 LH tap out of some drill rod on the lathe and mill with indexing attachment. Since I only needed to use it once on Delrin, I didn't go to the trouble of hardening it. It worked great for me. Eric ------- Tapping guide [sherline] Posted by: "arcmaster3" tomx~xxwade.name Date: Thu Jan 7, 2010 12:20 pm ((PST)) Have a bunch of holes to tap. Have a hunk of 1 1/2" square steel bar stock, and was thinking of making a tapping guide. Anyone have a good idea how tall the tapping guide should be? Was thinking about drilling holes for #4, #6, #8, #10, #12, 1/4. Any suggestions for other sizes I should include? Tom Wade Hope, In ------- Re: Tapping guide Posted by: "Michael" Michaelx~xxkbuilt.net Date: Thu Jan 7, 2010 12:38 pm ((PST)) Tom, I have one I bought a while back that is 1 inch high. Michael ------- Re: Tapping guide Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Thu Jan 7, 2010 12:50 pm ((PST)) Mine is 1.2" tall and works fine for those sizes. D. ------- Re: Tapping guide Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Thu Jan 7, 2010 12:56 pm ((PST)) This has been addressed a number of times. The solution, which I have used, is to go buy a handful of 1/2 X 1 inch bolts. Chuck up the threaded end, turn the top of the bolt, drill a hole though the bolts to fit the size of the desired tap, just a little bit over size. Works fine if you are using a piece of flat stock. Dan ------- Re: Tapping guide Posted by: "Greg.Procter" procterx~xxihug.co.nz Date: Thu Jan 7, 2010 2:10 pm ((PST)) On Fri, 08 Jan 2010, wrote: > Hi Tom, Google < Bauer Precision # 110 Hand Tapper > > A boss unit ! I really dig it...... Jerry G (Glickstein) About 1/8" taller than you finally make it. ;-) My serious answer is that the "U" has to accommodate the tap holder, longest tap and the widget you wish to tap and a little clearance. Make the upright pillars from a basic size of round rod - that way you can quickly make longer ones when you find the originals are too short. The taller they are the more flexible they will be! Greg.P. ------- 6 x 18, Basic Threading question for a rookie [atlas_craftsman] Posted by: "mstrauch858" mikesx~xxpgisd.com Date: Mon Jan 25, 2010 9:10 am ((PST)) I'm sure you machinists out there will find this question pretty basic but that's why I'm asking you guys. I have a 6 x 18, 101.07301. I am new to the lathe but have come up to speed ok. I have tackled some of the basics, Facing, Side cutting, boring, etc. Now I am working on chasing a thread on the outside of an aluminum rod; I have it all set up to cut 20 TPI on a 1/4" shaft, tail stock in place, speed set to around 80 rpm. I have been able to make the first cut no problem, now getting to index the second and future passes is where I need some advice. I have the thread dial engaged and have noted where I engaged the saddle for the first cut but when I try and match that for the next pass I miss by this much and bugger the whole thing up. Please let me know how you guys do it there must be a trick and I know practice will be part of it but I'm willing to put in the time I just need a procedure that works. Don't hesitate to go basic on me -- I need it. Thanks in advance. Mike ------- Re: 6 x 18, Basic Threading question for a rookie Posted by: "Dean" deanwx~xxbmi.net Date: Mon Jan 25, 2010 3:52 pm ((PST)) Hi Mike; I don't know if you just "picked some spot" on the thread dial, or if you picked a specific place to start your threads. For cutting even numbered threads, like 20 TPI, you have to start the thread dial at a specific point for your first cut, and continue with that point for subsequent cuts. That specific point is "1", or the mark on the thread dial 180 deg around from "1". You need to choose one of those marks every time you engage the halfnuts. There are other ways to do it, but just stick with this method to simplify things until you get it sorted out. If you mean you are having trouble getting the halfnut to engage exactly at the number "1", maybe your halfnut mechanism is a little dirty. It's hard to hit the mark if the halfnut lever is stiff. Start the carriage at a point that lets the cutter "cut air" for about half an inch before it starts cutting the threads on your piece. This way, if you miss your mark on the threading dial the first try, you can disengage and try again when the number comes around again. If you have the cutting bit right next to the work, and you engage the halfnut a little off, it will start to cut before you can disengage it. Give yourself a little breathing room. Another problem could be that the gear on the bottom of the threading dial is not engaging the lead screw properly. It's adjustable. If it's not meshing well, it could be skipping a tooth now and then, which will throw the dial off in it's calibration with the halfnuts. That problem will have you cutting threads all over the place. Make sure the lead screw is clean where the thread dial gear runs in it. If it has a bunch of crud in the threads, it will sometimes push the thread dial gear out of the thread on the lead screw, and once again, you lose your spot. Ask again if this didn't cover your problem. Dean ------- Re: 6 x 18, Basic Threading question for a rookie Posted by: "Dean" deanwx~xxbmi.net Date: Mon Jan 25, 2010 8:46 pm ((PST)) Hi Mike; I put a few things between the lines of your last post. > Thank you Dean, very clear answer. > I will try starting in the air giving myself some room. > The machine is completely clean and re lubed so the thread > dial meshes well, I just did not know how to use it, the nut also > engages fine. > > Question, once I engage the nut and run my first pass. I then disengage > the nut (keep the dial on the screw) run the saddle back past the work > and start the procedure all over again catching the dial at the same > spot? Yes. Before you crank the carriage back to your starting point, back out the cross slide, or you'll take the tips off the threads you just cut. > I found that once I engage the nut the thread dial stops spinning; > is that correct? Yes, it's normal. When you engage the halfnut, the carriage is moving in sync with the lead screw. The threading gear is then just following along on the same tooth, all the way down the lead screw. > So as long as I engage the nut in the same spot it will index to the > chuck and start the threads in the same place? Yes, it will be in sync with the spindle. > I await your answers since I am still a little confused how the thread > dial stays indexed to the chuck, it also seems that if you don't nail > that mark then you're a mess. That's why I suggested you engage the halfnut with the tool 1/2" or so away from the threads you are cutting. It gives you a chance to see if you caught the dial before it actually starts cutting. When you have the lathe gears set up to cut threads, as long as you leave the reverse tumbler in the same position, (forward, in this case), the spindle and lead screw are always in time for that particular thread. The carriage is the variable in this situation, since it is the only thing that is ever disconnected from the gear train/lead screw/spindle. You disconnect it by opening the halfnuts. Even though you move the carriage back and forth, independent of the lead screw and spindle, the threading dial is keeping track of its position in relation to the lead screw and spindle, because it is always in contact with the lead screw, even when the carriage is not. Try to find a video on cutting threads, as Hank suggested. Check Youtube. If you find a good one, it will tell you about the threading dial, along with setting the compound to 29 deg, using the cross slide only for backing out of the cut, using a fish tail for setting your tool properly. Taking a test skim cut to check thread count. All that good stuff. It's a lot to tell here in one whack. Dean ------- Re: 6 x 18, Basic Threading question for a rookie Posted by: "n1ltv" n1ltvx~xxyahoo.com Date: Tue Jan 26, 2010 12:14 pm ((PST)) Mike: If you try doing some very coarse practice threads (like 8 per inch) in a piece of soft plastic, it will be easy to see the right marks to use on the thread dial and you can just get some plain old threading technique practice on material that's easy to cut. Hank ------- Re: 6 x 18, Basic Threading question for a rookie Posted by: "Mike Nicewonger" twmasterx~xxtwmaster.com Date: Tue Jan 26, 2010 2:36 pm ((PST)) PVC pipe is great to practice threading on. Cheap too. ------- Re: Internal Threading [atlas_craftsman] Posted by: "jmartin957x~xxaol.com" Date: Fri Jan 29, 2010 11:19 am ((PST)) wheezer606x~xxverizon.net writes: > Group, > I would like your insight into the process of creating 6 tpi > internal threads in either mild steel or 6061 T5 Al. > This would thread onto my lathe spindle to hold a collet chuck > at the other end. What tool to cut with, lube, speed, angles > or reference to an articles about the process? Thanks lance The tool to cut with will depend on what you have - forged threading tool, boring bar with user-ground HSS 60 degree bit, boring bar with commercial HSS or carbide threading insert, or a short commercial HSS or carbide threading bar designed for use in a boring head. All will work. Just keep in mind that the helix angle for a 6 tpi thread can be pretty steep, and factor that in when you check the clearance angles on your cutter. Lube would be whatever you normally use on the material you choose. Speed should be about the slowest you have. At 6 tpi, your threading dial will be moving right along, and you want to make sure you engage the half nuts at the proper time. And, of course, DIS-engage them at the proper time. Screwing up either operation may break something. If you are threading completely through your workpiece, the job is a lot easier as you don't have to worry about opening the half nuts at the proper time. Cutting a runout groove at the end of the thread will make things easier. Since you can't see the tool inside the bore, a carriage stop or even a magnet stuck to the lathe ways will let you know when to stop. Toolmaker48 mentioned threading from left to right, with the lathe in reverse. It's not a bad method. A couple of caveats, though: make sure your chuck is screwed on tight or hold it with a setscrew, and be very careful to engage the half nuts fully and at the proper time. Feeding from right to left you have a few turns to make sure everything is OK before the cutter hits the work, but from the inside out you don't have that advantage, even when starting in a run-out groove. I like feeding from right to left, with the spindle in the normal forward rotation, but with the tool bit upside down and cutting on the backside of the bore. You set the compound to the same 29 or 29-1/2 degrees you would when external threading and feed with the compound, but use the crossed to quickly retract the cutter at the end of every cut. Use a crossfeed stop so you don't have to rely on the crossfeed dial, just as you would when external threading. The motions of backing out the crossfeed and releasing the half nuts will be exactly the same as when external threading, which helps keep you from making a mistake. And the chips fall away from the cutter. Cutting on the near side of the bore, you have to remember to run the crossfeed IN before you release the half nuts - and that can take some getting used to. Plus, you can't use the crossfeed stop. Keep your tool projection as short as possible, and keep the compound overhang to a minimum. Use the largest and stiffest tool you have that will fit the bore. Double-check the clearance angles. Practice withdrawing the crossfeed and opening the half nuts a few times without the tool near the workpiece. Pull the chips out of the bore after every few passes. John Martin ------- Re: Help ! Threading tool broken on first use :-( [myfordlathes] Posted by: "dnaman43" mevagissyx~xxgmail.com Date: Sun Feb 7, 2010 7:55 am ((PST)) "eddyfonfon" wrote: > The tool broke in the middle of the third pass, but it was exatly "in groove"... I still do not know if i took a too large cut or if the tool was defective...( broke in middle of carbide tip ) < One thing that I don't think has been mentioned ... you probably took care of it but I'll mention it anyway: You don't have any significant backlash in any of the movements do you? The first time I tried to cut a thread on my Chinese 5x7 I made the first couple of passes OK, then the work just grabbed the tool and it was game over. I had noticeable backlash between the leadscrew and half-nut. ------- Re: Help ! Threading tool broken on first use :-( Posted by: "Barry Kneller" bkba09515x~xxblueyonder.co.uk Date: Sun Feb 7, 2010 8:21 am ((PST)) If you have backlash in the lead screw half nuts, the easiest way to deal with it is to apply a little pressure to the manual feed wheel.......just the palm of your hand resting on it will do the trick. ------- Re: Help ! Threading tool broken on first use :-( Posted by: "dnaman43" mevagissyx~xxgmail.com Date: Sun Feb 7, 2010 9:12 am ((PST)) If you've done that and it works, Barry, then I have to bow to it but I must say I'm surprised. My experience has always been that once the work has grabbed the tool bit, nothing is going to stop it and it's hard to see where a little light hand pressure will make much difference on top of the inertia of the whole carriage assembly. ... but I'll give it a try next time I'm in that situation. Oh, I just thought - which way do you bias the feed wheel? I'd been assuming that you bias it against the feed (in the same manner as the carriage inertia) but if you bias in the feed direction ..... ------- Re: Help ! Threading tool broken on first use :-( Posted by: "Barry Kneller" bkba09515x~xxblueyonder.co.uk Date: Mon Feb 8, 2010 2:47 am ((PST)) Bias the wheel in the against the direction of travel, as if you are trying to slow it down - use enough pressure to take all the backlash out of the manual drive rack - this was shown to me by my instructor when I was learning to screwcut and I just do it automatically now. ------- Re: Help ! Threading tool broken on first use :-( Posted by: "eddyfonfon" eddy.fontainex~xxpandora.be Date: Sun Feb 7, 2010 10:52 am ((PST)) The backlash is not my problem here i think. It broke about halfway of the thread length, at about 3/4 inch of the thread start. I suppose a backlash problem would break the tool at the start of the thread, when it reaches the job ..? Eddy ------- Re: Help ! Threading tool broken on first use :-( Posted by: "Sid Knee" mevagissyx~xxgmail.com Date: Sun Feb 7, 2010 11:06 am ((PST)) > I suppose a backlash problem would break the tool at the start > of the thread, when it reaches the job ..? Not necessarily. In principle there shouldn't be a problem at all since the cutting forces should act against the tool pushing it to one side of the backlash. The problem comes when the tool picks up slightly in the work (due to a rough spot, vibration, etc.) and tries to pull into the work. If you have much backlash, there is nothing to prevent the tool digging in for the amount of the backlash and the forces are then enormous. It may stop the lathe or it may break the tool. This can happen at any point in the cut. ------- Re: Help ! Threading tool broken on first use :-( Posted by: "MikeD" durnfjmx~xxaol.com Date: Sun Feb 7, 2010 12:50 pm ((PST)) I think we are getting all a bit theoretical here, yes, the cutting forces should push the tool against the driving force and therefore a pickup *could* pull the tool into the cut, but there should also be some friction, stiffness and inertia holding it back, and we *are* talking light cuts - on a Myford Lathe. My advice to the OP, would be to get a piece of HSS, grind up a tool the right shape, hone the edges very carefully, set it precisely to (or very slightly below) center height, then get a piece of something out of the scrap bin roughly the same composition and size as the original workpiece, chuck it up, and try again - and again, and if necessarily again, until he can identify which part of the operation is causing the problem. (Unless of course, he can get someone to stand by his shoulder, who knows better than him, to show first hand!) OK, it all takes time, but it will be time well invested for the development of his turning, and analytical, skills. Stay safe, MikeD ------- Re: 27 TPI [atlas_craftsman] Posted by: "PeterH" peterh5322x~xxrattlebrain.com Date: Sun May 16, 2010 10:47 pm ((PDT)) On May 16, 2010, Dave Clements wrote: > After 25 years I found something my old 12" Craftsman w/quick change > wouldn't do. I needed to single point some 11/16" X 27TPI internal > threads but the QC skips from 26 to 28. 11-1/2 and 27 tpi, both of these being pipe threads, are missing from many engine lathes, but are usually found in toolroom lathes. ------- Re: 27 TPI Posted by: "n8as1x~xxaol.com" docn8as Date: Mon May 17, 2010 2:44 pm ((PDT)) havent checked the cfrtsmn manual in long time cause w/ the 20 or so gears, imcluding a 127 TpI, i can cut near any thrd on my 1895 14 inch Reed, but i think there are setups there for special thrds such as pipe thrds ...requires some xtra crftsmn change gears .....fwiw ...my crftsmn commercial 12x36 is one of very few quick changes that will cut a winchester model 12 barrel thrd ...30 TPI ....& the need was there a few times. best wishes docn8as ------- Re: 27 TPI Posted by: "James Walther" indianfourriderx~xxyahoo.com Date: Mon May 17, 2010 3:31 pm ((PDT)) The MLOMT has the setup for 27 TPI. You can get the manual from Clausing for I think it's $25 +s&h. I use mine all the time. If, however, you're cheap like me and really don't want to spring for the book, I can scan the two pages you'd need and post them. Jim ------- Re: 27 TPI Posted by: "rod rowzee" rrowzee1954x~xxhotmail.com Date: Mon May 17, 2010 3:57 pm ((PDT)) > does this page help? > http://bellsouthpwp.net/t/h/thib9564/Atlas_Lathe_Threading.htm for newer lathes: http://bellsouthpwp.net/t/h/thib9564/Atlas_Lathe_Threading_Modern.htm ------- NOTE TO FILE: Both of the above pages are very useful for Atlas lathe owners to keep handy. The standard gears needed and the setup are clearly shown for most threads we will ever use, including the 27 tpi. But not the relatively rare 30 tpi that Doc mentioned. ------- [Tailstock Threading Dieholder] Taistock Threading Dieholder for the Sherline Lathe [sherline] Posted by: "lhbakeland" digitaltorquex~xxaol.com Date: Tue May 25, 2010 10:40 pm ((PDT)) Some two years ago, I purchased the LittleMachineShop.com #2314 Tailstock Die Holder for the Sieg C2/C3 mini-lathe. http://www.littlemachineshop.com/products/product_view.php?Prod uctID=2314&category= In the interim, although I still have a mini-lathe as a spare for large parts, I do most of my machining on the Sherline. Well, the tool from LMS sat in my tool drawer, until today. So, using my Sherline, both the 1MT and 0MT adapters that fit the 3/8x24 threads on the drill chuck, and a piece of 5/8" 303 stainless steel round bar, I made an adapter for the LMS tailstock die holder and tried threading the end of a long shaft. This thing is really sweet. If I didn't already have the dieholder, it would be quite easy to make one, since it's just a hunk of aluminum round bar with a hole bored in the middle with counterbores for the dies and a few set screws to hold them. I also drilled out the center of the free end of the shaft to 5/16 diameter a couple of inches deep to increase the working depth of the dieholder. For those interested in making the 0MT tailstock shaft, here is the technique I used. 1. Hold the stainless bar in the 3 jaw Sherline stock. 2. Drill and tap one end for 3/8x24 threads. 3. Screw the 1MT Sherline adapter into the 3/8x24 tapped hole and lock it into the spindle of the Sherline lathe. 4. Center drill the free end and drill out the end using successively larger bits to 5/16 diameter and about 2 inches deep. 5. Using a live center for support (probably not needed), I turned down the shaft to match the bore of the die holder. I used the LMS dieholder, but it can be any reasonable diameter of your choosing, if you made your own dieholder. 6. Remove the 1MT adapter and screw on the OMT adapter, and you're done. While this unit is not as versatile as the Sherline Threading Kit, it is very convenient to use to thread rod and shaft ends, as well as threading stem shafts on engines and clock parts. I hope this might be useful to other Sherline users. Regards, Leo ------- [Cutting Metric Threads on an Atlas] Re: Collet adapter options for Atlas 618 [atlas_craftsman] Posted by: "anthrhodesx~xxaol.com" Date: Mon Jun 28, 2010 10:01 pm ((PDT)) In a message dated Jun 27, Peter H. writes: > Well, I have a 100/127 transposer and all the stud gears which are required to generate ANY customer and "model-maker' required... NO need, at least not on my part, to use an approximation. < Peter, I presume your 100/127 conversion gear(s) are not for an Atlas 618. Since the idea is to cut a metric thread for an attachment to be used on a 6" Atlas it is most helpful to post solutions which will be usable by a person who has access to only an Atlas 6". That's not to say that other solutions are unwelcome, simply not quite as useful. If you know where one can acquire a 24 DP 127 gear, please so advise. The standard Atlas conversion set is 44 driver / 52 driven. This results in an error of 6 parts in 10,000 (1.00060606). The basic reason for this conversion set is it uses two of the standard Atlas gears. A couple of alternatives which would require non-standard gears are 52 driver and 66 driven or 26 driver and 33 driven. Each of these results in the same error and would require making or acquiring additional gears but the additional gears in the change gear train to cut specific metric pitches might be easier to calculate. You would, of course, have to calculate your own gear trains or adapt a change gear chart from a non-Atlas lathe. An example of a metric pitch (which is no longer listed in the manual for the Atlas 6") which could be cut with one of these conversion gear sets is 16 driving idler driving 33 followed by 26 driving 40 which results in 0.5 mm pitch (0.50030303 mm). Two other gear sets that require non-standard gears but give reduced errors are 37 driver / 47 driven sometimes used by Logan and resulting in an error of 2 parts in 10,000 (1.00021281), and 63 driver / 80 driven resulting in an error of 1-1/4 parts in 10,000 (1.000125). As with the alternatives in the previous paragraph, they would require making or acquiring additional gears but the additional gears in the change gear train to cut specific metric pitches might be easier to calculate. You would, of course, have to calculate your own gear trains or adapt a change gear chart from a non-Atlas lathe. 16 driving idler driving 47 followed by 37 driving 40 gives 0.499893617 mm and 16 driving idler driving 80 followed by 63 driving 40 gives 0.5000625 mm. Of course the ultimate conversion ratio requires a 127 driven combined with one of various alternative drivers but very large gears like the 127 are difficult to fit into a gear train on a lathe as small as the Atlas 6". There are alternatives, you could probably write a book on the subject. In fact, Martin Cleeve has, "Screwcutting in the Lathe". Anthony Berkeley, Calif. ------- Thread Cutting Attachment / Tools [sherline] Posted by: "KWC" kencondalx~xxyahoo.com Date: Fri Sep 17, 2010 11:36 am ((PDT)) I'm about to order the Sherline thread cutting attachment for my lathe but am unsure of which cutting tools to order for making both inside and outside threads. The documents say that a 60 degree cutter is good for outside threads and Sherline has several of those to choose from. I'm just not clear on which cutter to buy for inside threads. Any suggestions? Thanks, Ken ------- Re: Thread Cutting Attachment / Tools Posted by: "Hamilton Elliott" helliottx~xxmicroflex.ie Date: Fri Sep 17, 2010 11:43 am ((PDT)) Hi Ken, I haven't tried any inside threads, but, if using a carbide cutter make sure you back off the cutting tool when moving back to the start of the thread or you will damage the carbide tool. Regards, Hamilton ------- Re: Thread Cutting Attachment / Tools Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Fri Sep 17, 2010 12:00 pm ((PDT)) This one: http://tinyurl.com/2ugtc8t David Clark in Southern Maryland, USA ------- Re: Thread Cutting Attachment / Tools Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Fri Sep 17, 2010 12:08 pm ((PDT)) And now, you have seen the pic of the cutting tool, realize, you can grind your own. DanD. ------- Re: Thread Cutting Attachment / Tools Posted by: "Ken Condal" kencondalx~xxyahoo.com Date: Fri Sep 17, 2010 1:09 pm ((PDT)) Thanks David. I was looking under Lathe Accessories where they show every tool except this one. Duh. ------- Re: Thread Cutting Attachment / Tools Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Fri Sep 17, 2010 3:34 pm ((PDT)) You're welcome. Good luck with your new learning. Don't be discouraged if your first attempt at thread cutting doesn't go smoothly. Sherline's gizmo will work. It works very well -- once you get the hang of it. But that may take a little practice. Once you set up the attachment for a given pitch, before you even put a workpiece or a tool in the lathe, crank the handwheel many turns in and out repeatedly. See what comes loose in the gizmo. Something will. Most likely the gears will jam or jump out of mesh. Takes a little wiggling, a few tries, to get everything lined up, solidly engaged, and tight. And put a light coat of grease on everything. Do not try cutting threads for the first time on a good workpiece that you have already put a lot of effort into. Don't try to learn by cutting 0-80 threads in half hard brass. Get some material that's really easy to machine, like 12L14. Say 3/8 or 1/2 inch diameter. Take some practice cuts. Don't even worry about achieving a particular standard thread until you feel confident using the attachment. Patience, practice... you'll get it. Let us know how you're doing. DC ------- Re: Thread Cutting Attachment / Tools Posted by: "R.L. Wurdack" dickwx~xxnwlink.com Date: Fri Sep 17, 2010 4:36 pm ((PDT)) Excellent advice. Be sure you have the gizmo set up and tight before you attack anything you're proud of, and be patient. I wouldn't like to make 1000 screws using the Sherline system, but it has done a remarkably fine job on my 49X1 mm adaptors for telescopes and microscopes - one off kind of work. Dick ------- Re: Thread Cutting Attachment / Tools Posted by: "Bert Harless" bharlessx~xxq.com Date: Fri Sep 17, 2010 1:38 pm ((PDT)) It's possible but it's also tricky to get the angles right. It's not like you can just crank these out by hand on a bench grinder, at least not on my bench grinder. You have got to make the point 60 degrees and centered and getting the undercut right is hard to do by hand. A diamond disk in a Dremel works pretty good if you just take a little off at a time and inspect it under a magnifying glass after each pass. If you screw up you have pretty much ruined the whole tool blank and will need to start over. It's too bad someone doesn't make a simple device to hold parts while grinding. I've thought of making one but don't want it to get really complicated or expensive. Maybe something like the magnetic base to hold the DI, where you could put it at the angles you need and clamp it down. What do you guys use? Bert ------- Re: Thread Cutting Attachment / Tools Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Fri Sep 17, 2010 1:49 pm ((PDT)) A. start with a 1/4 HSS tool blank. B. get your handy dandy Starrett gauge part number C391, for angles C. look at the pic to get the approx point to narrow D. get a bowl of water to cool the tool as you grind it E. start grinding.... to match the picture What do you have to lose for trying? One end of a 1/4 inch HSS blank. Maybe buy a professionally ground tool and use it to compare to your efforts. Even if you buy and use the tool, at some point you will have to sharpen it. When you get confident, you can knock one out in less than 15 mins. It may not be as pretty as the professionally made tool but, if you have the cutting edge right, you will be home free. Wanna see the tool I made? LOL DanD. ------- [sherline] Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "wongsterwish" wongsterwishx~xxyahoo.com.sg Date: Fri Sep 17, 2010 5:58 pm ((PDT)) A little OT on threads. I'm thinking of making a little stand for a Sony camera so that I can clamp it on my work area to take videos or still short for my blog. How do I measure the internal threads on the camera to know what size threads to cut? Regards, Wong ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Fri Sep 17, 2010 6:03 pm ((PDT)) Wong: If you can find the directions for your camera, it will give you the thread information. Failing that, go to a camera store and ask them. The camera stands pretty much all have the same thread so you can pick and choose the stand you like. DanD. ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Jeffrey T. Birt" birt_jx~xxsoigeneris.com Date: Fri Sep 17, 2010 6:06 pm ((PDT)) There is a 99% chance that it is 1/4 - 20 as that is the 'standard' for camera tripod mounts. Try [carefully] threading in a 1/4 - 20 bolt; if it fits then you are done. For unknown internal threads you can try to measure the diameter of the hole and compare to a tap/drill table looking at the major diameter column. This will get the possibilities down to a few common thread types. If it is an off the wall thread you'll need a thread pitch gauge to measure it. Jeff Birt ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Fri Sep 17, 2010 6:22 pm ((PDT)) Hi Wong: All small camera tripod threads are 1/4 - 20 British Standard Whitworth regardless of the country of manufacture. A 1/4 - 20 UNC works fine. Very large cameras use 3/8 - 16 Whitworth. A few things will never go Metric -- too much legacy. DC David Clark in Southern Maryland, USA ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Tue Sep 21, 2010 1:00 pm ((PDT)) If you want to adjust the tightness of the fit between threaded parts, it is the male part that is varied (that is why button dies are split and can be adjusted). It is much easier to measure and control the male thread which is why the specifications on threads are always much tighter on the male thread than the female thread - BSI typically allows three to four times the tolerance on the nut minor diameter compared to the bolt top diameter. Ian ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Tom & Judy Bank" trbank1x~xxverizon.net Date: Wed Sep 22, 2010 1:52 pm ((PDT)) "chieftoolmaker" chieftoolmakerx~xxearthlink.net wrote: > Hi Ian, what is your opinion of the use of a taper tap in a through hole (not blind)? Regards, Jerry G (Glickstein) < Personally, my impression is that the taper tap was developed for use by non-machinists to hand tap when they don't have an adequate tapping tool and also lack the mental faculties to realize they should invest in one. Although I should add that with very hard material it is sometimes convenient to tap with a taper as far as you can conveniently, then switch to a plug to deepen the partially cut threads, then back to the taper to go a little further, etc. In such situations on through holes (which is what we are discussing) it also helps to have gun taps. Regards, Tom Bank ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "chieftoolmaker" chieftoolmakerx~xxearthlink.net Date: Thu Sep 23, 2010 11:42 pm ((PDT)) Tom, Are you joking? I doubt that a tool/tap was developed on the factors you mention. It is my understanding that a taper tap is to ease into the threading. For harder alloys, etc. Gun taps are my favorite, but I do have a few forming taps for more ductile materials.....No chips and a stronger thread. Regards, Jerry G (Glickstein) ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Pierre Coueffin" pcoueffinx~xxgmail.com Date: Wed Sep 22, 2010 5:20 pm ((PDT)) Sometimes a workpiece is large enough to be worth tapping by hand rather than disassembling, taking it inside and using a tapping fixture. ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Bert Harless" bharlessx~xxq.com Date: Thu Sep 23, 2010 8:05 am ((PDT)) Not to mention that not all of us can afford to have all the right number size drills and have to go with the closest fractional size. The difference between the number 21 which is called for on 10x32 and the fractional 5/32 is .159 vs .15625 =.00275. A tapered tap is much easier to start. I know having the right tool for the job is critical but being able to improvise shows a certain degree of mental faculties as well. Bert ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Pierre Coueffin" pcoueffinx~xxgmail.com Date: Thu Sep 23, 2010 8:14 am ((PDT)) On that topic, I recently bought a set of metric drill bits. They go up by half a mm per bit and usually fall between two fractional bits. Gets me closer, and was much cheaper than buying the number drills. ------- Re: Thread Cutting Attachment / Tools - OT: Threads on camera mounti Posted by: "Art Fish" 1art2fishx~xxcomcast.net Date: Thu Sep 23, 2010 9:41 am ((PDT)) Another thought on the bits...Get the size needed for tap and clearance size for 6-32, 8-32, 10-32 and 1/4-20, or whatever size bit you need or don't have. Go to your local Home Depot, Lowes's or home town hardware, and buy 1 each of the ones you need. For probably less than $15 you can get the set, will provide all you will ever need and for much less than the cost of an index. On the other hand, if you only have use for the size of a 6-32 tap size bit...just buy that one...probably $1.50, and you'll always have it, no guessing what other size 'might' work. Art Fish Corvallis, OR USA Back in Time Clock Repair ------- Thread taps [sherline] Posted by: "RICHARD WIECKOWICZ" tmdlbearsx~xxyahoo.com Date: Sun Oct 3, 2010 2:43 pm ((PDT)) The many Youtube videos from Tubal Cain (mrpete222) on machining and metalworking are very useful training. The most recent ones deal with the basics of taps and dies. A new series of instructional youtube videos by Tubal Cain, an Illinois machinist, is now showing tapping methods. Highly recommend his clear- cut, no frills techniques: www.youtube.com/user/mrpete222 ------- new guy, needing info [barstockengines] Posted by: "largrin" LarGrinx~xxaol.com Date: Thu Oct 7, 2010 5:22 pm ((PDT)) Hello All, I am new to this group, and to small engine building. This seems to be a very nice group you have here. I had a friend that passed away a few years ago, but in years prior to that, he gave me a tour of his shop. He had an impressive collection of model steam engines he had built. From an elaborate 4 cylinder, down to a wobbler that he sat on a dime. He was an amazing craftsman. I have been in machine shop for 38 years. I am able to do most machining operations. I have an old Leblond lathe, a HF mill, and a little drill press. I also have a Gingery shaper that I built, and a horizontal mill that I built from the Phoenix plans in HSM. I bought the Rudy Kouhoupt book- Working Steam Engines, and I think I can do those projects, when I get smaller tooling. I have never worked below tap size 4-40. I need some information. I want to buy an assortment of taps and drills, and I want to buy good stuff, not junk, so I need a good supplier. I have a catalog from Micro Fasteners, and it looks pretty good. Are there any other recommended vendors out there? Next question is- does anyone have a plan for a shop built sensitive drill press? I can come up with something, but I much prefer experienced opinions. Thanks for reading, and thanks for any info or advice you can give me. Larry in WV ------- Re: new guy, needing info Posted by: "brian carter" briankenyn2x~xxyahoo.com Date: Thu Oct 7, 2010 6:21 pm ((PDT)) Hi Larry: First things first, I'm a retired banker who is careful with his funds. Having said that, I have explored a load of tool sources in my efforts to find taps and dies. One source will have one or two taps and no dies, or vice versa, so it pays to hunt around. I'm a good deal less discriminating than you are, and am happy to take HC (High Carbon) taps when I can get the sizes I'm looking for- including very small, odd sizes and fractional. Accordingly, here are some suppliers in order of quality: Enco - good quality and selection MSC Industrial Supply - same McMaster - Carr - Generally good with less selection Reiff Nestor- Haven't used them but the site seems to speak to quality Brownells - I find this a good source for odd sizes in taps and dies - but all HC. HW Wilson Engineering- Don't remember ordering from them, but seems comprehensive. Victor Machinery Exchange - good selection of low priced taps and dies - seem ok - I have a few. Hope that helps a little. Regards, Brian ------- Re: new guy, needing info Posted by: "largrin" LarGrinx~xxaol.com Date: Fri Oct 8, 2010 6:32 am ((PDT)) Hi Brian: That helps a lot. Thanks for taking the time to make that list. I have dealt with the first three over the years, and I know they are good vendors. I will spend some time today looking at the others you listed. Like you, I don't want to waste good money. But I will spend it freely for good quality, because I get good results. When it comes to actual "name brand", I am not too discriminating. I just don't want generic stuff. For example, there is a young man I am teaching machinist work to. He got real excited and bought a tap and drill set from Lowes in the Kobalt brand. The drills are pathetic. They just are too soft. The taps don't feel crisp edged and sharp like the better brands. But, as they say, you get what you pay for. Again, thanks for the list. I will use it well. Larry in WV ------- Re: new guy, needing info Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Fri Oct 8, 2010 6:01 am ((PDT)) Hi Larry: Further to Brian's comments about using carbon steel taps - I would recommend always using CS rather than HSS taps for the following reasons: 1) They stay sharper for longer (HSS is much better than CS at high temperatures, but at the normal temperatures encountered in tapping CS wears better than HSS). 2) They cost less (about 1/2 to 2/3 the price of HSS in the UK) 3) You can soften them at a sensibly low temperature to make it easy to drill out any broken ones (it happens to us all). Unless you are doing heavy machine tapping in a production environment, the temperature of the tap does not get high enough for you to see the benefit of HSS. There is only one reason for choosing to use HSS taps and that is due to the manufacturing process rather than the material properties: CS taps are made by cutting the blank using a master die, grinding the flutes, then heat treating the tap to harden it. Although the heat treating is done under careful control, it will introduce some small amount of distortion. This means that you will have problems if you try to re-sharpen the tap in a tool and cutter grinder. HSS taps are made by grinding the threads into a fully hardened blank. This means the thread is always accurate to the centre of the tap (and is likely to be a more accurate thread generally - but QC (Quality Control) comes in here so this is a theoretical point). This means you can resharpen the tap by mounting it on the centres at each end. The inherently more accurate thread on HSS taps may be important if you make micrometers, but otherwise all taps are made to some sort of standard of accuracy so this is not something I worry about. As for resharpening - I do not have a T&C grinder so I'm not concerned with this activity (the best my taps get is the occasional touch with a little slip stone). In fact I grind the centre point off the end of most of my plug (bottoming) taps anyway, so they can reach as far down blind holes as possible. Ian ------- Re: new guy, needing info Posted by: "largrin" LarGrinx~xxaol.com Date: Fri Oct 8, 2010 6:54 am ((PDT)) Hi Ian, thanks for the input. I am familiar with what you are saying. You explained it well. On most of my starter taps, I have ground the ends off too. Just enough that it will still start easily, but it will go deeper into a blind hole. Most of the taps that I currently own are HSS. This is because the company bought them, and when I retired, the boss told me to keep the ones in my tool box. I had maybe 100 of them, so I am well stocked. In fact, I have only purchased one tap in my life. Of all things, deep into a project, Ine eded a 7/16 tap, and did not have one. Anyone ever try the tapping fluid from Grizzly called Safe Tap Ultima? I used it 2 days ago to tap some 3/4-10 holes in 4140. I am impressed. It is now my new tapping fluid. I used to used Moly-Dee, and it is excellent, but makes a nasty mess. As for my slow replies, I am still on moderation on this group, so I have to wait to get my messages posted. I don't have a problem with that, Iun derstand the reasons. Just the way it is. Larry in WV ------- Re: new guy, needing info Posted by: "brian carter" briankenyn2x~xxyahoo.com Date: Fri Oct 8, 2010 8:27 am ((PDT)) Hi Larry - Yeah, I know- that Lowe's stuff is trash. Take a look at Brownells site - they are good people, will take back anything no questions asked. Despite having the outward appearance of seeking life long air condition- ing and minimal labor, I was really misplaced- I've had a war-worn Atlas 6x24 since I was in HS '50s, and have always loved metal crafts. I built a wobbler in the '70s [didn't do anything for 25yrs] and then another eccentric valve engine just recently after I retired. I'm working on a ported .750 / .625 model that I found in a '44 Popular Science article [available if you're interested]. Many of the UK models call for fractional sizes and very fine threads - 1/4 40, by example, or 1/8 some- thing or other- pitch escapes me just now - Hard to find in matching sets. I have researched a number of free engine sites and plans along the way some of which are really, really iteresting [and available]. There's a fellow with the nickname, Bogstandard from the UK that has published a very fine, two cylinder marine engine complete with plans and instructions, that I would love to build - no sweat for you, but I'll end up making and remaking parts for quite a while 'til I get it. Regards, Brian ------- Re: new guy, needing info Posted by: "gratianx~xxgmail.com" gratianx~xxgmail.com Date: Fri Oct 8, 2010 8:28 am ((PDT)) Hi Larry, Here is an old Popular Mechanics article about a sensitive drill press that might give you some ideas: http://books.google.com/books?id=9dkDAAAAMBAJ&lpg=PA88&dq=pop ular%20mechanics&pg=PA135#v=onepage&q&f=false If that link gets broken up by yahoo, try this one: http://tinyurl.com/28uxl5f regards, Gratian ------- [Subject is actually about cutting to match an unknown thread.] Re: Cutting BA tHreads on Sherline -- Warning: Tangent [sherline] Posted by: "Tom & Judy Bank" trbank1x~xxverizon.net Date: Wed Oct 13, 2010 9:08 pm ((PDT)) > Maybe I asked the question wrong. I have hole with a known diameter and I've chosen a pitch, how do I determine the diameter to machine the male cylinder to prepare it for threading. Likewise, if the male (before threading) is known, how do I determine the female diameter before threading? < I just had to do some threading -- not BA, but then. The talk of the fine pitch threads makes my efforts pertinent. Maybe some members of the group have heard of the OttLite, a "natural light" fluorescent. The one my wife got cost about $100.00. It consists of a weighted base, a two piece pole, a length of flex stuff, and a head with a proprietary fluorescent bulb. The problem we had was with the two piece pole. The two tubes of thin steel are threaded at the joining ends for about half an inch each with a fine thread on the inside. Into these threads is screwed a white metal cast coupling with male threads which is about 3/4" long. That leaves about 3/8" of thread in each of the tubes. Further, the male thread on the cast coupling is undersized by 0.012", which is about the depth of the threads on a side, -- not the depth of both threads on the opposite sides. At any rate, the threads gave out. The lamp head flopped over. Being a Sherliner, I tore everything apart and cut a new coupling piece. Mine is steel, it has a full inch of thread, and it is 1-3/4" long over all, with a reduced (no thread) 3/8" section at each end to add support for the joint. And the threads are a tight match! To answer Ken's question, below, I used a thread gauge to determine the thread count; guessed at the major diameter, going for the high side; then began cutting threads -- and as I got to the point where the thread profile started looking like a saw tooth form I began testing with the female thread in the tube at the end of each pass. My eyesight isn't good. The threads are .012" deep. I cut threads .050" deep before I finally got down to the right size, starting out taking .0025" cuts and then shifting down to .001" cuts and -- as I began to close in on the proper size -- finishing up with .0005" cuts, which reduced the major diameter of the connector threads by .001" per pass. It took a while to do the job, but eventually I got done, and the wife"s prized $100.00 light is back in business. I'm wondering, though, how many non-Sherline owners are out there who threw these lamps in the trash with a string of vile language because they didn't have the means of fixing the problem. For me, that one little part amortized a sizable portion of the price of my Sherline threading setup. Regards, Tom Bank ------- NOTE TO FILE: The following question about threading is from a fellow living in a very isolated area (The Falkland Islands), and he wants to accomplish his goal without having to order much stuff from outside. There is no imperial change gear and using a closest metric thread has an error that would only be okay for a few threads. ------- Thread chasing [myfordlathes] Posted by: "norman.valentine" ongata_rongaix~xxyahoo.com Date: Fri Dec 24, 2010 12:18 pm ((PST)) Hi, I have access to a Myford 254 metric equipped with a gearbox. I need to make 2 parts with an internal thread to fit a 68mm x 40TPI thread. Is this something that could be cut using a chaser? I don't want to spend a lot of money on a one off requirement so I was considering buying a 3/8 x 40 ME tap and somehow using that as a chaser. Has anyone any ideas on how I could achieve this? Thanks, Norman ------- Re: Thread chasing Posted by: "JOHN QUIRKE" jjquirkex~xxeircom.net Date: Sat Dec 25, 2010 2:42 am ((PST)) HI Norman: The tap can be used sucessfully if you clamp it in a piece of square with a slot cut in it in the toolpost and use the nearest set up with the gearbox (with the 5 % error) to complete about 3/4 of the thread depth and finish the thread by hand with the tap as a handheld chaser. John ------- Re: Thread chasing Posted by: "norman valentine" ongata_rongaix~xxyahoo.com Date: Sat Dec 25, 2010 4:57 am ((PST)) Hi John, that sounds like the sort of advice I was looking for. I can see that working. I was worried about how I would get the thread started. You have answered my question, thank you very much. Norman ------- Re: Thread chasing Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Sat Dec 25, 2010 8:14 am ((PST)) John: Not being a very experienced machinist, I have not tried hand chasing a thread before and am interested in learning more about your method. Am I right in thinking that after screwcutting the 0.6mm thread to three quarter depth you disengage the screw feed, clamp the tap longitudinally in the toolpost, force the tap into the workpiece using the crossfeed, then rely on the interference between the tap and the part-formed thread to pull the saddle along the bed at the correct rate? Bearing in mind that 0.6mm pitch is a pretty fine thread, is there enough interference to overcome the friction in the saddle and its handwheel geartrain without chewing up the thread? Alan ------- Re: Thread chasing Posted by: "JOHN QUIRKE" jjquirkex~xxeircom.net Date: Sat Dec 25, 2010 2:41 pm ((PST)) HI. No. Take the tap out and grip it in a vice grips so the vice grips and tap are in line. Remove the tool post clamp and position the near side of the center bolt of the tool post inboard of the inside of the workpiece by approximately the tap diameter. Use the slowest speed possible and lever the tap onto the work using the center bolt as a fulcrum. Small adjustment of the cross slide will allow the tap to be aligned with the lathe centre line. A support block of wood under the tap helps maintain horizontal alignment. Final finishing is best done using the tap in the vice grips freehand with the slide out of the way. John ------- Re: Thread chasing Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk Date: Sat Dec 25, 2010 10:12 am ((PST)) Hi Alan: Thread chasing is a useful skill to learn but it is now more a skill used by woodturners rather than metalists. As a general rule you are asking for trouble if you hold a chaser in the tool post, unless the screw cutting gears are set correctly. Thread chasers are normally hand held and this is where the skill comes in, getting the thread started, once started the chaser follows the thread. Have a look at; http://www.youtube.com/watch?v=jslgNh5b-S8 You will notice he starts on the corner, then brings the tool around once a thread has been started. Always start with over size material in case you make a series of grooves instead of a thread. The technique is to turn down the OD to size, once you have something to follow, and then cut the thread to the right depth; it is not a good idea to keep cutting the full thread if it is still oversize. Other than learning the skills, which will come with practice, what is required is a tool rest that the chaser has to be able to slide freely on. This rest must be very close to the work and be at such a height that the chaser's top surface is a continuation of the radius. Give it a go if you can find the chasers, but first try on a close grained wood, like Boxwood if you can find it. For the metal turner, chasing is a good way of getting the correct thread form after single point threading. CJ(UK) ------- Re: Thread chasing Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Sat Dec 25, 2010 11:30 am ((PST)) Hmm, yes. Well I can see it works on wood, but I would imagine it is a bit more tricky on metal, especially if, like Norman, you are cutting an internal thread. With an external thread you can rotate the tool on the rest to start the thread, as shown in the video, but you can't do this with an internal thread, can you? And how do you work to an accurate dimension? Or do you just make the first part roughly to size and then keep on reducing the mating part until it fits. Alan ------- Re: Thread chasing Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk Date: Sat Dec 25, 2010 1:50 pm ((PST)) Hi Alan: It is perfectly possible to cut both internal and external threads in metal with hand held chasers. That is how it was done in the old days, before screw cutting lathes had been invented. Someone was indeed cutting threads with a chaser on the SMEE stand at the Sandown exhibition last fortnight. I think they were demonstrating a gift to SMEE by Tracy Tools of some chasers. Yup, one part is made to fit its matching one. Actual size is relatively unimportant, they just have to fit each other. These techniques are even older than British Standards threads sizes. CJ(UK) ------- Re: Thread chasing Posted by: "crawleystones" dickmx~xxwaitrose.com Date: Sun Dec 26, 2010 8:10 am ((PST)) JOHN QUIRKE wrote: Use the slowest speed possible and lever the tap onto the work using the center bolt as a fulcrum... I've never tried this in metal, but have done threads in wood. A couple of points that might be worth adding to the above. 1. It helps to start an internal thread with the chaser pointing at 10-20 degrees towards the centre line of the workpiece until it starts to get drawn in to a thread. (That is probably just another way of saying "levering the tap onto work using the bolt as a fulcrum") 2. A bit obvious, but make sure you have enough of the smooth part of the tap exposed for it to slide to the end of the internal thread without getting caught. If anything catches on the centre bolt as the chaser is being drawn into the workpiece and before you reach the intended end of the thread, you will chew up any incipient thread and have to start again. Chasers for wood have their lower (and upper) surfaces flat, to rest on the toolrest (or the wooden block suggested above). Might be worth grinding two opposing sets of "teeth" off the tap if you don't mind sacrificing it, as this would give a bit better resistance to the tap rotating in the work, and would give better clearance above the cutting edge. Dick Morris ------- What size 3/4-16 thread for Sherline spindle? [sherline] Posted by: "sportandmiah" sportandmiahx~xxyahoo.com Date: Tue Dec 28, 2010 6:22 pm ((PST)) I notice some taps are NC,UNF,NF,GH3...ETC. Which tap would i need to make a faceplate? thx ------- Re: What size 3/4-16 thread for Sherline spindle? Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Tue Dec 28, 2010 6:37 pm ((PST)) NF Get both the taper and the bottoming tap. If you can only want to buy one, by the taper, IMO (usual disclaimer here) DanD. ------- Re: What size 3/4-16 thread for Sherline spindle? Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Tue Dec 28, 2010 10:04 pm ((PST)) DanD., (Sport), Do you have any prejudice against plug taps? They are most likely the most used between/of the three choices. The face plate is a through thread and the bottoming tap would not be as suitable. Jerry G BTW, NC = National Coarse UNF = Unified Fine NF = National Fine GH3 is not a thread specifically, but a class of tolerance. i.e. ------- Re: What size 3/4-16 thread for Sherline spindle? Posted by: "DA Dossin" danatlx~xxyahoo.com Date: Wed Dec 29, 2010 3:11 am ((PST)) JerryG, I have nothing against the plug tap. I have one of each, 3/4X16. But, some folks just want one and it may be difficult to start a plug tap. As per the face plate being a "through" piece of equipment, using a tapered tap, you have the advantage of turning it over and re-tapping (chasing) from the other side if necessary. Or, am I miss reading what you wrote? I have been known to do that more and more each day. Or maybe, I did not say what I meant? And I did include my usual disclaimer. DanD. ------- Re: What size 3/4-16 thread for Sherline spindle? Posted by: "Jerry G" chieftoolmakerx~xxearthlink.net Date: Wed Dec 29, 2010 7:31 am ((PST)) DanD., I would avoid tapping from both sides. Too much chance of crossing the threads. Starting any tap, if done properly is no sweat. Perpendicularity is the key. Break the chip frequently by backing up at intervals. Use the right cutting fluid for the material. Correct tap drill as well. Think thusly. 6-3-1 * 6 = # of threads removed on lead of taper tap 3 = # of threads removed on lead of plug tap 1 = # of threads removed on lead of bottoming tap You may not have said what you meant, but you should always mean what you say..... Later, Jerry G ------- Re: What size 3/4-16 thread for Sherline spindle? Posted by: "danp" danx~xxpines.co.il Date: Tue Dec 28, 2010 10:49 pm ((PST)) Hi. The best fit for the spindle thread on the Sherline can be achieved using NF 3/4-16" H2 tap. H2 is tolerance class. Sherline said this is the best class to fit their spindle thread. This is according to information received from Sherline. Note that 3/4-16" already indicates that it is an NF thread so no problem if these 2 letters are missing. danp ------- What is H2? [sherline] Posted by: "loonitech" loon432x~xxverizon.net Date: Wed Dec 29, 2010 9:08 am ((PST)) Hi All. H2 is a clearance specification. Every size thread has a pitch diameter (which varies for different major diameter threads), and this pitch diameter is the same for both the inside and outside version of any given thread size (theoretically perfect). If the pitch diameter is the same for both the inside and outside thread, you will have metal to metal contact between the two and the fit will be so tight the thread will bind. This is where the H specification comes in. Each "H" number equals an increase of 0.0005" to the pitch diameter and is applied only to inside threads. If the inside and outside PD (pitch diameter) are equal, you have H0(zero). H1 would indicate the PD of the inside thread is 0.0005" larger than the basic dimension for that thread, therefore a specification of H2 would indicate a tap will cut a thread that has a PD that is 0.001" larger than the basic dimension for the thread. You will never buy a tap that has a H0 spec. The higher the "H" number, the less precision the thread will be. By the way, the basic pitch diameter is the theoretical diameter at which the distance through each thread equals the distance across the groove between each thread. Terry Looney ------- Re: What is H2? Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Wed Dec 29, 2010 10:14 am ((PST)) Hi. There is a slight problem in using the H designation: There are the international standards defined by the ISO and used throughout most of the world, and there is the ANSI definitions used in the USA (but not many other places). Check this document for a quick overview: http://www.sutton.com.au/Assets/1401/1/IPD05MeasurementThread_tap.pdf Ian ------- Re: What is H2? Posted by: "loonitech" loon432x~xxverizon.net Date: Wed Dec 29, 2010 11:16 am ((PST)) Hi Ian: Thank you so much for posting the additional information. My description was meant to be very basic and I neglected to mention that it applied to the Unified thread system. Thanks again Terry Looney ------- Re: How to put a 1-1/2"x8tpi chuck on a 3/4"x16tpi- [atlas_craftsman] Posted by: "jo barden" jobarden422x~xxmsn.com Date: Thu Dec 30, 2010 2:06 am ((PST)) Hi Richard I have a Drummond M type to go with my Atlas and I needed an adapter similar to you. First off get some free cutting steel, leaded if possible, now practice cutting the exterior threads at slowest back gear, small cuts, lots of lube. Once you are happy do the same on the actual adapter, then centre drill, followed by bigger drills until you can put a tap through. Honest it is daunting but taken in small bites it is not hard, you only need to buy the free cutting steel and the 3/4 x 16 tap. I hadn't done screwcutting for 25 years and even then it was only once but practice on scrap first and it will be fine. Jon G6UWK ------- Re: How to put a 1-1/2"x8tpi chuck on a 3/4"x16tpi- Posted by: "jmartin957x~xxaol.com" Date: Thu Dec 30, 2010 12:58 pm ((PST)) In a message dated 12/30/10, gcrimminsx~xxyahoo.com writes: > You can buy chuck adapters from places like Penn State Industries (less > expensive) or Oneway (higher qaulity.) If you can't find what you need > Oneway will even custom make one. I would advise a bit of caution with > a large chuck on a 3/4" spindle. A good catch while turning could > bend the spindle. --Geoff It looks like Penn State's Barracuda chuck has a 1-1/2 x 8 body thread, and they offer it with an adapter to fit a 3/4 x 16 spindle, so there may be an off the shelf adapter that will fit. There may be others, but it is hard to tell - most of the descriptions of woodturning chucks do not mention the body thread size. Packard and Craft Supplies are two of the specialty woodturning supply mail order firms, and may be able to help if Penn State cannot. Then there are the woodworking suppliers - Woodcraft, Rockler, etc. Whether the 1-1/2 x 8 adapter will fit your chucks perfectly is not certain. Lathes meant for metal turning usually have a non-threaded register section designed to locate the chuck perfectly. The Penn State adapter may or may not have such a register, which may or may not fit the register which may or may not be present in your chucks. There's a good chance everything will fit, but you may have to do some fiddling. And the fit may not be as snug as you'd want it for metal turning. Worth a try, though. I agree with the above poster's caution about the metal chucks being a bit heavy for your lathe. I'd be worried not so much about a catch as about the weight on your spindle bearings, though. I've made two different adapters to switch chucks between my Atlas 6" metal lathe (1 x 10) and Delta wood lathe (1 x 8). If you make your own adapter, which is easy to do, you need both. I first held a piece of 1-1/2" 12L14 round in the Atlas 3 jaw, and bored and threaded it to fit the Atlas spindle. I periodically removed the entire chuck and workpiece to test the fit against the Atlas spindle, and got it just right. Then I mounted the workpiece directly on the Atlas spindle and turned the external threads to fit the Delta attachments. Why bother with that first adapter, when what you really want is the adapter to go from the wood lathe spindle to the metal lathe chucks? Simple. To do a good job on the second adapter, you need to mount it on the first. And it's awfully handy to have the first adapter when making up chucks to fit the wood lathe. To make the second adapter, do essentially the same as for the first one. Hold your stock in the chuck on your metal lathe and bore and thread it to fit the wood lathe spindle. Remove the entire chuck and workpiece to test the fit against the wood lathe spindle. When you get it right, mount the first adapter on your metal lathe and then screw the new one onto it. Cut the external thread and register to fit your metal lathe chucks, and you're done. Someone advised using a 3/4 x 16 tap to cut your internal thread. I'd advise against it. It's a good way to clean up an internal thread, but when tapping an unthreaded piece it is hard to get the threads straight and perfectly centered. Single pointing them is best. Plus, it will give you a better fit. Mill or even file wrench flats or hexes on the adapters, or drill them for tommy bars or pin spanners. John Martin ------- Taps and Dies [myfordlathes] Posted by: "Steve" black19650x~xxo2.co.uk Date: Mon Jan 24, 2011 11:12 am ((PST)) I am currently adding to my collection of taps and dies and want to buy quality. So.. given that I am mainly looking for imperial sizes which old manufacturers should I be looking out for? Any advice gladly accepted. Steve ------- Re: Taps and Dies Posted by: "meatblubber" meatblubberx~xxyahoo.co.uk Date: Mon Jan 24, 2011 1:27 pm ((PST)) Hi Steve: Try to get hold of some 2 piece dies if you can. I don't own any but used to use them years ago. One of the advantages of using these is that the depth of cut could be set to as small or as large as you like, unlike dies with a single split in them. (Not as much adjustment in the 1 piece dies.) Presto, Hall, Osbourne. To name a few... Happy Hunting! Tim ------- Re: Taps and Dies Posted by: "Andrew Curl" methuselahx~xxntlworld.com Date: Mon Jan 24, 2011 2:30 pm ((PST)) The old firms that still supply the old stuff have already been mentioned. Don't forget Totem, and don't dismiss high carbon stuff. High carbon is -harder- than HSS, holds an edge just the same, but it cannot take heat. Drills and lathe tools, this can be a problem. Not taps and dies. For the small stuff, you can go straight in. Over a certain size, you should be screwcutting, then finishing to size with taps and dies... 1/2" Whit. is a notorious tap breaker. Avoid Tracy's. Another hot tip when tapping is to pay attention to percentage thread engagement. Threads only work at the effective p.d. and tapping hole sizes given in the manufacturers' booklets are often smaller than those we model engineers (and engineers, too) actually require. 65% is usually perfectly sufficient, and the tables are given in Tubal Cain's book "Drills Taps and Dies" in the appendices. Don't forget that the action of tapping any hole is a mixture of cutting and extrusion, and even this will vary with the material. Andrew ------- tapping fixture [Prints_and_Plans] Posted by: "Oshb5" andyx~xx0acs0.co.uk Date: Sun May 1, 2011 9:26 am ((PDT)) Hi. Does anyone have any plans for a DIY tapping Fixture please? Andy ------- Re: tapping fixture Posted by: "Bill F" bfmanx~xxinsightbb.com Date: Sun May 1, 2011 10:20 am ((PDT)) Andy: In the Photos section under a folder named BF there are plans for a basic tapping stand... ------- Re: tapping fixture Posted by: "MartinD" omikamix~xxyahoo.com Date: Mon May 2, 2011 5:18 am ((PDT)) Harold Hall (Model Engineer's Workshop) has put his version of a tapping stand with automatic feed online: http://www.homews.co.uk/page41.html The drawings are on the second page. ------- screw cutting [myfordlathes] Posted by: "we'realldoomed" sardinesarniex~xxyahoo.com Date: Mon Jul 4, 2011 3:26 pm ((PDT)) Hello. Please could someone offer some advice on screwcutting? I've done screwcutting before on larger manual machines, so I'm ok with toolsetting, principles etc. These machines had reverse facility, which makes things much easier. I have a super7 with gearbox and a motor that only runs forward. When cutting a metric thread on an imperial machine, or any thread for that matter, what is the correct procedure to take the tool back to the start of the thread for the next pass? I can think of a couple of ways: 1. Stop the spindle and rotate the chuck by hand in reverse direction until the tool is back at the thread start position. A very long winded method on a long thread I think. 2. Engage half nuts at a mark on the thread indicator, disengage at end of thread, manually wind saddle back to start of thread position and re-engage half nuts at the same mark on the thread indicator dial. Are there any other ways to do this? I don't intend to change my motor to a reversing one! A google search shows all sorts of opinions and advice, but which one do you guys use? Many thanks and kind regards, ------- Re: screw cutting Posted by: "Ken Strauss" ken.straussx~xxgmail.com Date: Mon Jul 4, 2011 3:41 pm ((PDT)) The only way that is guaranteed to work is to *NEVER* disengage the half-nuts if doing metric threading with an imperial leadscrew. Why not just fix the no-reverse deficiency? FWIW, I usually thread forward using a hand crank and use the motor reverse to get back to the starting point. ------- Re: screw cutting Posted by: "Andrew Chapman" Chapmanadx~xxaol.com Date: Mon Jul 4, 2011 3:43 pm ((PDT)) Well, I don't want to seem any more smug than is entirely necessary but... My S7 has a 3-phase motor with an electronic controller. I run it slow when thread-cutting and fast when reversing. It is one of the great advantages of that setup. As you say, there are lots of other methods but they are all annoying. That's why I have the setup that I do. Kind regards, Andy Chapman ------- Re: screw cutting Posted by: "Robert Mitchell" rmm200x~xxyahoo.com Date: Mon Jul 4, 2011 6:27 pm ((PDT)) Let me vote for putting a reversing switch on the motor. I have not seen a motor used on a Myford that would only run one direction. Robert Mitchell ------- Re: screw cutting Posted by: "anthrhodesx~xxaol.com" Date: Tue Jul 5, 2011 8:33 am ((PDT)) sardinesarnie, Double sided single tooth dog clutch. Read this thread: http://www.model-engineer.co.uk/forums/postings.asp?th=49358#951976 on the ME web site. Anthony Berkeley, Calif. ------- Re: screw cutting Posted by: "Andrew Curl" methuselahx~xxntlworld.com Date: Wed Jul 6, 2011 2:25 am ((PDT)) I cannot remember the last time I screwcut under power at home. I am a jobbing engineer by trade, and spent most of my time on centre lathes. At home I use a mandrel handle. There are some motors around (like the "gryphon" I use) that have a dangerous tendency to continue running in the same direction if you flick the switch in a rush, too... I do use a Dewhurst drum switch. Andrew ------- new article: An Easy way to Single Point Turn a Thread [atlas_craftsman] Posted by: "RG Sparber" rgsparberx~xxaol.com Date: Sun Aug 14, 2011 8:53 pm ((PDT)) This procedure was generously given to me by Frank Petrin of the Valley Metal Club of Phoenix, AZ. If you are interested, please see http://rick.sparber.org/ftt.pdf Your comments and questions are always welcome. All of us are smarter than any one of us. Rick ------- NOTE TO FILE: Rick's initial article prompted tremendous discussion and suggestions over the next couple of weeks. The article on his site has been completely updated with reader input. Well worth reading. ------- NOTE TO FILE: The Sherline group was having a discussion in October 2011 about how to get better results with the manually operated Sherline threading attachment made specifically for that lathe. {Parts of that conversation can be found here in the Sherline Lathe Quirks or Tips file.) Then the discussion changed to if and why an offset to 29.5 degrees of the top slide was needed. The following site has an excellent illustration of the different threading approaches for any make of lathe. http://www.mmsonline.com/articles/threading-on-a-lathe ------- Re: gear train for screw cutting , super 7. [myford lathes] Posted by: "Andrew Curl" methuselahx~xxntlworld.com Date: Mon Jan 9, 2012 5:08 am ((PST)) I really would asvise that until you are fluent with screwcutting, you obtain (and use) a mandrel handle, and leave the half nuts engaged throughout. This is by far the safest way to do it, as the motor is never even turned on. You have complete control of the tool's progress, and you will also avoid the chance of re-engaging the half nuts in the wrong position. As for sizing threads without "official" gauges, for standard sizes, tap out a piece of barstock, and use that. For other stuff, where you are likely to be making both the male and female threads, cut the female thread first. If you rough bore to the minor size, then finish bore with the screwcutting tool itself before screwcutting, you'll know where the major diameter is going to end up, so when finished, you can use the female component itself as a gauge. If you are making both threads, for something for yourself, and they screw together as they should, it doesn't really matter if they are not dimensionally perfect to B.S. standards, does it? Pukka gauges can come later, if you feel such stuff necessary. It is expensive, though, probably costly enough to put you off the idea -- I'm thinking Ovees, thread measuring parallels, ring gauges, shadowgraphs and the like. I have all these things, but... One really good solution is full form carbide tooling. A different tip is used for each pitch, so if you cut your blank a couple of thou. oversize, you can then measure directly over the male thread crests as you go, and if you have the specs. in front of you, you can make a perfect thread with nothing more than a micrometer every time. Whitworth is easiest, because of the way it's specified -- if a male thread is one or two thou. under nominal size, it is "in limit". Metric is a bit different in this respect, and you'll want "the book". Now this carbide tooling isn't that cheap, but you can buy odd tips at shows. Engineers' Merchants sell them in boxes of ten, but RS splits these boxes and sells them in twos instead, which is more affordable, if that's the way you want to go. All of my male screwcutting is done with these things, female threads are cut with a "part profile" insert -- right 55 or 60 degree angle, one tip does all, all gauged by the mating component. For the book, I have spent the vast majority of my career as a centre lathe turner, screwcutting under power; I have never used anything other than a mandrel handle at home. I do so comparatively little screwcutting, it is not an issue, and it allows me to use the absolute minimum length of undercut, which is frequently important on the small stuff I make. Largest I've screwcut at home were the 1.25"x32 tpi threads on a Quorn spindle. I've gone past 5" diameter by thread milling. Standard pitch threads are produced with a coventry diehead, around here -- that *is* used under power. Andrew ------- [How to identify the thread in a hole -- a female thread] Industrial stand thread sizes [myfordlathes] Posted by: "cdavisonx~xxbtinternet.com" cdavisonx~xxbtinternet.com Date: Mon Jan 16, 2012 2:35 pm ((PST)) Hello, I am relatively new to this group but not to the planet (unfortunately). I have just picked up an industrial stand for my rather aged Myford. I naively thought that the two drain holes on the tray would be BSP but it appears not. Does anyone know what the thread sizes are? They seem quite fine but paint and use have rather gummed then up. Best rgds Chris ------- Re: Industrial stand thread sizes Posted by: "Robert Mitchell" rmm200x~xxyahoo.com Date: Mon Jan 16, 2012 2:40 pm ((PST)) My low-tech method would be to run a tapered wood dowel into the hole -- and then measure it with a ruler. The threads make a nice imprint. Robert Mitchell ------- Re: hex /sq. holes [atlas_craftsman] Posted by: "Vaughan Seed" vseedx~xxparadise.net.nz Date: Mon Feb 6, 2012 12:58 pm ((PST)) Good morning, Just a note on British thread systems - Whitworth is not a collective name for all the British thread systems - it refers only to the single BSW (British Standard Whitworth) when it was adopted as the standard (coarse) thread to try and unify the myriad of individual threads previously used when every manufacturer had their own thread standards within their factories and there was significant variation in head size and arrangement. BSF (British Standard Fine) and BA (British Association) are the fine thread series as indicated; most UK cars threads were BSF until the European/Japanese firms took over the UK motor plants and they are now mostly metric series threads. The vibration etc indicating fine threads. BA threads go down to very small diameter and was mostly used on instruments and small appliances. So BSW and BSF are equivalent to UNC and UNF. Note - BSW and UNC are pretty much interchangeable - the only difference (for the most part) being the thread angle. Cheers Vaughan New Zealand (where we use all these systems routinely British -US -Metric depending on what we are working on at the minute ------- Re: hex /sq. holes Posted by: "wa5cabx~xxcs.com" Date: Mon Feb 6, 2012 1:45 pm ((PST)) Actually, BSF and BSW are both listed under Whitworth Threads in the Machinery's Handbook. British Standard 84:1956, Parallel Screw Threads of Whitworth Form, covers both. You are correct that the BA thread form is not Whitworth. But BSW and BSF are. Whitworth is a 55 deg. thread form. BA is 47.5 degrees. ------- Re: hex /sq. holes Posted by: "Paul" kimchex~xxQuixnet.net Date: Mon Feb 6, 2012 4:18 pm ((PST)) Hello all. The Feb./March issue of "Machinist Workshop" has a 5 page article on screw threads. It has 2 pages that compare threads, a brief review of forms; covers metric, U.S., British, square, etc. Hope it helps. Paul Orting, WA. Qc10x54 jet 8x15 ------- Shaper Feed Nut S7-32 material? [atlas_craftsman] Posted by: "rhino_johnmc" JohnMcMillianx~xxboisepaper.com Date: Thu Feb 23, 2012 5:34 pm ((PST)) I need to make a new feed nut, part S7-32, for my shaper. The threads are plum worn out. The one in it looks like brass or bronze. What should I use to make a new one out of? The screw looks practically brand new, it is in wonderful shape. ------- Re: Shaper Feed Nut S7-32 material? Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Thu Feb 23, 2012 8:30 pm ((PST)) the original ones appear to be brass.....bronze wud be longer wearing, harder to cut & harder on the leadscrew..think i wud go w/ atlas used ...there shud be some wear on the screw as well...if you intend to single point the acme threaded nut, i wud take some measurements & if worn as i expect, i wud take a cleanup cut on the screw to true it up ...then when you single point the nut, & cut it to fit the screw, near ALL lash will be removed.....i have single pointed 7/16 X 10 square threads as well as 1/2 X10 acme, so it is very feasible. best wishes docn8as ------- Re: Shaper Feed Nut S7-32 material? Posted by: "rhino_johnmc" JohnMcMillianx~xxboisepaper.com Date: Fri Feb 24, 2012 1:47 pm ((PST)) Well, then brass it is for the new one. Makes sense, far easier to replace the nut than the screw. I do not have the correct tap so will single point it on my lathe. Thanks for the feedback. John McMillian ------- odd threads. [atlas_craftsman] Posted by: "Dave Clements" davidcclementsx~xxgmail.com Date: Sat Mar 3, 2012 9:05 pm ((PST)) I need to cut some 3 TPI acme threads. Is there any way to get a AC 12" QC to do 3 TPI? I lent my manual to a friend half the state away who just got a 10" Atlas. The chart only goes down to 4 TPI. Dave ------- Re: odd threads. Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Sat Mar 3, 2012 9:12 pm ((PST)) The manual is in the files area under "Operation and Parts Manuals" http://tinyurl.com/qcgbmanual You will need to change the standard gear set driving the gearbox. Scott G. Henion Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 ------- Re: odd threads. Posted by: "wa5cabx~xxcs.com" Date: Sat Mar 3, 2012 10:37 pm ((PST)) If you've already downloaded the QCGB instructions (URL sent by another list member) you may have already come to the same conclusion as I did. Call Clausing on Monday. As best I can figure out by referring to the QCGB parts list and the requirements chart for 3 tpi, you need a 24t gear, two 48t gears and a 32t compound gear. You have two 48t and a 40t available. But nowhere can I find what compound gear is already available. It looks to me like the compound gear shown in Figure 14 in the QCGB instructions (Figure 164 in the Manual of Lathe Operations) is mounted in Position C. But the chart says to put a 48t gear there. So I can't figure out from the two manuals what's needed that isn't already on hand. It may be that the existing compound gear is a 32/16t. But where would it go? Hence the phone call. But anyway, at a minimum you are going to need a 24t gear and a spacer. Robert & Susan Downs - Houston wa5cab dot com (Web Store) ------- Re: odd threads. Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Sun Mar 4, 2012 3:38 am ((PST)) Dave: 3 TPI is a large thread for a small lathe. Once you have your gears you need to rough out the thread first meaning: cutting from the sides of the thread and for your final cuts I recommend a tool bit ground close to size and for the final cuts you will still need to cut the sides. This will eliminate chatter and give you a good thread. I used to make long acme screws with 1 3/8 threads per inch and 10 feet long and 4 inches in diameter. That was the way I had to do it to produce a good quality thread. Once you start feel free to contact me I will be glad to help. GP ------- Re: odd threads. Posted by: "Ray" ray.waldbaumx~xxyahoo.com Date: Sun Mar 4, 2012 10:42 am ((PST)) Dave, I just looked at my acme thread gauge and the tip of the tool for 3 TPI is .110" wide. Are you using some really free machining material? I recently made a 1/2" x 10 TPI LH acme cross feed screw on my 10" Atlas and that was quite a challenge as the thread got deeper. Yes, I used a follow rest. Your threads are going to be a lot deeper and wider. I'm really interested in how that turns out. ------- Re: odd threads. Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sun Mar 4, 2012 10:50 am ((PST)) This will be pushing the gear train VERY hard. You want to set up for 6 TPI and then add an additional 2:1 gear up in the train. If you don't have any loose gears, then it becomes quite difficult. Jon ------- Re: odd threads. Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sun Mar 4, 2012 11:02 am ((PST)) Yeah, I really have some doubts it can be cut like that on an Atlas. Anything with a wide chip causes horrible chatter. Just try ordinary turning with a cutoff blade that is 1/8" wide and see if that happens. If so, the thread cutting will be MUCH worse. I think the only way to do this on an Atlas is to mill the thread. You could probably use a 1/16" solid carbide end mill in a die grinder, or even a Dremel tool. You might make a simple slot first, then rotate the toolpost or compound slightly to mill the sides of the thread. You would probably follow the thread by turning the carriage leadscrew, and letting the gear train rotate the spindle through the gear train. I did a face thread (scroll) this way once, and it worked out quite well. The other way is to grind the thread with a toolpost grinder set to match the helix angle of the thread. But, grinding the entire thread would take forever. I also made a replacement crossfeed screw some years ago, and it was a slow process indeed to keep from having chatter. I made the cutter narrower than normal, and made alternating cuts on the left and right flanks, and then one down the middle. It made a great screw, but it took a couple evenings. Also, I made it right-hand by mistake! Arrgh! Jon ------- Re: odd threads. Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Sun Mar 4, 2012 12:05 pm ((PST)) FWIW if you can get your hands on a gooseneck (spring) threading tool bit holder, it will cut your chatter problems in 1/2 ....maybe cutting a v thread first will also be beneficial. as Guenther said, using a roughing bit slightly under width but full depth first, & then a bit to size will give cleaner thrds. one way to do this final cut is, if you have the female, use a slightly under width bit, take the cut with the xslide, then advance the 14 1/2 * compound a tad, & take a cut w/the xslide, then back off the compound & take a cut on the other side w./ the x slide til the fit suits you... this works especially well w/ square threads & the compound set at rt angle to x slide ....i have cut several this way, but nowhere near the volume i am sure Guenther has & he may have a method that suits him better. pay attention to depth of thread. a gooseneck thrd tool holder will make life much easier. best wishes docn8as ------- Re: odd threads. Posted by: "jerdalx~xxsbcglobal.net" jtiers Date: Sun Mar 4, 2012 1:25 pm ((PST)) You will strain the heck out of the gear train in the normal way of setup.... even without much depth of cut... you'd be better off to drive the leadscrew, and let IT drive the spindle through the gears, that is a step-down, not a step up ratio. With a 10 TPI thread, you need to run the leadscrew 3.333... turns for every spindle turn. Might work, but it's on what I'd call the "edge of worthwhile" to try that way. Then also, no way you will use a full form tool for that on an Atlas. I would count on using a series of tools to rough out and then finish the form, just the same as they used to make coarse threads 100 years ago. Rough-cut the groove first, well short of the faces, working it outwards towards the thread face surfaces. Then rough the angles close to final shape and form. Last few passes will be to finish the thread faces smooth, you will probably set your compound to the exact 29 deg angle and take passes feeding in across the face of the thread. Even with low depth of cut, I'd bet on chatter if you try to do the whole face. Sounds long, and may be long, but should go well if you take it the right way. I would suggest referring to the specs for that thread, and making a "male" template which you can try in the groove as you go along. And check pitch right away before you get more than a scratch on the work to mark your advance. JT ------- Re: odd threads. Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Sun Mar 4, 2012 2:37 pm ((PST)) JT You surely make a complicated operation out of the thread cutting operation. It's so simple. GP ------- Re: odd threads. Posted by: "jerdalx~xxsbcglobal.net" jtiers Date: Sun Mar 4, 2012 3:11 pm ((PST)) Complicated? Not hardly..... On the types of lathe you are used to, it IS simple.... set the QC to the thread and go...... I've seen a 2 tpi Acme cut on a large lift screw nearly 2 meters long, using a 20" Monarch. Didn't go quick, but it strained nothing. On a limber little Atlas, where the shaft to be threaded may be stiffer than the lathe (and maybe heavier than the bed), it isn't quite like that.... might be easier if an atlas had a feed rod, but they don't. I've seen threading via the feed rod on 1.5 meter swing machines from Poland, and it worked well for coarse threads. According to my figuring, a 3 tpi acme will have a width at full depth (minor diameter) of 0.125", and a thread depth of 0.176". For a full-form tool that is about 0.5" of edge in contact with the work. Maybe YOUR Atlas can do that, but it would be pretty rare. So yes, I figure you would have to choose one of several approaches that take more passes. 1) Rough cut and then finish out as described with whatever tools on hand will fit. That is predictable, if slow. 2) Take the regular ground full form tool, and step-cut a bit doen one face, then swap and step cut down the other, alternating until you get to full depth. Doing that you do not have full 0.5" length of contact until the final cuts. 2A) To make it go easier, a slightly narrower than spec tool would allow you to final cut the faces one at a time. 3) Use of a narrow cutoff type tool would allow a similar simple progression, and also allow using a tool you may have on hand, if care is taken not to overcut the width of the minor diameter flat. You can step cut down the flanks to rough out, then feed along them to finish. If light cuts are taken, the feed might be a low enough force not to strain stuff..... As I mentioned, it might work OK, the LS needs to turn 3.3333 turns per spindle turn to advance properly. So maybe driving the leadscrew externally is overkill for "only" a 3:1 speed-up. But you are entitled to your opinion. Go ahead and hog it in 3 passes if you must.... even the Monarch operator didn't do that, but every "hexpert" has their own way! ;-) JT ------- Re: odd threads. Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Sun Mar 4, 2012 3:26 pm ((PST)) http://www.google.com/url?sa=t&rct=j&q=u-tube%20cut%20a%20ma le%20acme%20thread&source=web&cd=3&sqi=2&ved=0CEMQtwIwAg&url=ht tp%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Ddhec5osxSs4&ei=WvhTT4 21LI3CsQLk5ajwBQ&usg=AFQjCNEY5Qd5tSKe9q0uLoPVCQRnSkAhLw Here is a u-tube like to cut acme thread. Also watch part #1 GP ------- Re: odd threads. Posted by: "jerdalx~xxsbcglobal.net" jtiers Date: Sun Mar 4, 2012 3:54 pm ((PST)) Sheesh............... he's cutting an acme thread of HALF the depth (6 tpi), in PLASTIC, on a 14" Clausing where the carriage probably weighs as much as a whole Atlas 12" lathe does.... Sure it looks simple...... because with that material and machine, it IS simple. The carriage of the Atlas likely weighs less than the compound of that Clausing..... just a tad less simple with the Atlas, lots more passes and less length of edge in contact. BTW, I think I said 29 deg earlier... that's the total angle... obviously the angle of the compound needs to be 1/2 the total thread angle. JT ------- Re: odd threads. Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Sun Mar 4, 2012 3:42 pm ((PST)) > You surely make a complicated operation out of the thread cutting > operation. It's so simple. GP If it is so simple, _you_ cut a 3TPI Acme thread on an A/C lathe. Most threads are trivial. Cutting one 1/6" wide and just as deep on a lightweight lathe is the issue. Many have seen using any kind of blunt cutter causes chatter on their lathes. It can probably be done in many light passes. After my latest improvements in reducing play in the cross, carriage and compound, chatter will probably be not bad. I do know as most of these lathes have aged, it would be difficult to do a smooth cut. The gear train would be stressed but I have done some 1TPI grooves by running the lathe real slow. Scott G. Henion Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 ------- Re: odd threads. Posted by: "Jon Elson" elsonx~xxpico-systems.com Date: Sun Mar 4, 2012 9:14 pm ((PST)) Dallas Richardson wrote: > G.P. > For us that are just learning.. I for 1 would love to see that laid out > from front to back on that making of those threads.. > In School, we had 4 hours of thread making and that included the > lathe time.. Every thing I'd give up my interest in hell to > learn how to be proficient at making threads.. Well, practice helps. Try light cuts with standard 60 degree screw threads in aluminum bar stock at slow speeds until you get the feel for engaging the half nuts snappily when the thread dial indicates the right alignment. Advance the compound slide in small increments for each pass, use the cross slide to back the cutter away and then return to the same setting each pass. The threads may not look great (depends on alloy) but you won't break anything if you goof. When you get the feel of it, then you can try upping the speed and threading mild steel. Jon ------- Re: odd threads. Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Mon Mar 5, 2012 3:24 am ((PST)) Yes practice makes perfect. Also I found with small machines that have 1 screw for feed and lead, engage the 1/2 nut and leave it engaged till the thread is finished, more so when one cuts fine thread -- and do that with any hobby machine. GP ------- NOTE TO FILE: The conversation continued. Personally I would not attempt a deep 3 TPI thread on a light weight Atlas or any other small lathe unless the material machined was very friendly, perhaps a plastic. While I cannot imagine what home project would need such a coarse thread, the discussion as to how it might be accomplished was interesting. ------- Screwcutting accuracy etc. [myfordlathes] Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk Date: Sat Apr 14, 2012 2:01 pm ((PDT)) On 13 April 2012 Andrew Curl wrote: >Subject: Re: Taper attachment mounting holes ML7 UN is a political thread that arose during WWII to supposedly allow limited interchangeability between English and US threads. If you had a big enough spanner. I don't know where all this b%ll&cks is coming from- they're not the same. And besides, if you can't make four simple bolts, why own a screwcutting lathe in the first place? Sorry, just had to ask. -Andrew UK < Hi Folks This is my first post on what seems to be a very active site. Thank you for allowing me in. The statement "if you can't make four simple bolts, why own a screwcutting lathe in the first place?" is very valid and just sums up my own feelings regarding many items that regularly come up for sale for our beloved machines. Why buy the stuff, when it can be made at home with a minimum cost. I appreciate that time is not always on our side and to be honest if all of the materials have to be bought at top price, then it probably is never going to be an economic proposition, but all the stuff I make (for me) is a one off, even when an outright blatant copy, it will have an element of my own input. This is what I have the lathe for. Right, having said that, on the subject of screwcutting. The difference in angles,radii, depths between Unified,Whitworth and Metric threads needs no input from me. But what I would say on the subject is this. I served my apprenticeship at Harland & Wolff Bootle, many years ago. To be honest the standard of work turned out was a real credit to the guys that worked there, given the fact that the lathes were well past their best. BUT, to say that it was fine work would not be true, Enormous YES. Back to screwcutting, even the small stuff was BIG, threads were made using tools ground to an angle freehand,(to a gauge) no radius at root or tip, etc. etc. Nothing ever gave any cause for concern. Now I totally understand that with tiny stuff 1/4" BSF etc. things are very different, but bolts for a taper attachment on an ML7 are never going to be the most highly stressed item we will need to make and the accuracy of them will, in my opinion be adequate. As I've come into this "debate" part way through, please allow for a newbie's lack of subject knowledge-------------Just my 2 pennies worth. Regards Bob ------- Re: Making or buying - was: Screwcutting accuracy etc. Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Sun Apr 15, 2012 12:57 am ((PDT)) Hi Bob, I agree with your sentiments - it is the attitude that I have when I need tooling for my own lathe (a Drummond flat bed made in 1910). I have fabricated fixed and traveling steadies, changewheel banjo, etc. Other people will scour the flea markets, carboot sales and ebay to get the original parts. It is here that you have ignored a very important issue - some people get enjoyment in owning the "right" things. As an example of this, many years ago I was in a tooling suppliers, looking covertously at a number of items, when I noticed an old gentleman cautiously handling a rather splendid mitre jig. At this point the gentleman's wife (a large, formidable woman who I would not be so impolite as to refer to as a Dragon, but I am sure she could turn bread into toast by breathing on it) entered the shop. She marched up to her husband and started to bark at him: "What are you doing?" "What have you got there?" "Why are you holding that?" Then the penny dropped... "You were going to buy that weren't you?" "You would get that and it would go in the shed with all of those other tools" "You would buy that and it would go in the shed and would you ever use it, would you?" "No! It would sit there and just like everything you would never do anything with it" At this point the old gentleman replied: "No, but it is just the pleasure of knowing that I have it" To this day I have an image of the old man going down to his shed when his wife is out shopping and just sitting amongst his prized possessions, oiling and caressing them. All the best, Ian ------- Re: Making or buying - was: Screwcutting accuracy etc. Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk Date: Sun Apr 15, 2012 2:24 am ((PDT)) Hi Ian. Your post raised a smile here and I can certainly relate to it. Here in the UK we have two companies, Aldi and Lidl. They send a weekly list of items for sale and these include "special purchases". Now some of these items are VERY INTERESTING and I find that although I've never had any of them previously, they suddenly become "Must Have's", certainly things that I never knew I needed. The reason that I make that statement is because I've found myself making stuff that falls into that category. I don't know if photos will come across with this text but here is the latest toy. And some previous stuff. I will put some photos in the proper area, but if these come across (and if it is acceptable) I will generally include a photo or two to illustrate better the text. Regards Bob [Note: no image can be attached to a Yahoo group message and he will have to upload pix to the Yahoo myfordlathes group's picture bin.] ------- Re: Screwcutting accuracy etc. Posted by: "David Alexander" dave_ale2008x~xxyahoo.co.uk Date: Sun Apr 15, 2012 1:55 am ((PDT)) "if you can't make four simple bolts, why own a screwcutting lathe in the first place?" I do own an S7 with a screwcutting gearbox, and can't make bolts. Not yet. If I don't own one I have no way of learning and practicing. my 2c. David Alexander Towcester, England ------- Re: Screwcutting accuracy etc. Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk Date: Sun Apr 15, 2012 2:44 am ((PDT)) Hi David: I've just realised that I have fallen into the trap and done something that I have accused many others of doing for years. That is --Assuming others have a degree of knowledge that they have not. (and there is no reason to make the assumption in the first place) I have worked in numerous companies and been the "new start"; everyone there seems to know where everything is and the pet names for places, etc. etc. etc. Whereas I know nothing. You get the picture????? Sooooo, let's start again and bear in mind that I am a NEWBIE to this group. I'm going to make another assumption. As I've not yet had a chance to look at the files section, (or anything else really) is there anything in there to help you with regard to screwcutting?? If not, I am pretty confident that Youtube will turn up something (no humour intended). If that fails there must be something available to download. Incidentally, I would suggest trying a nice big thread size as a first attempt. Something like Whitworth, or similar. Any mistakes will be far easier to spot and there will be far more material to remove than on a bsf thingy. If you need any help just ask. A bit difficult on line, but I'm confident we can get you started. Regards Bob ------- Re: Screwcutting accuracy etc. Posted by: "John" a.johnwx~xxyahoo.com Date: Sun Apr 15, 2012 3:25 am ((PDT)) Most people who own a lathe and make things finish up buying taps and dies and screw cut above a certain size or when work due to its dia or pitch/ thread form/size combination needs it. Few would bother making 1/4 bsf bolts via screw cutting. Few would bother making them at all and if it happened to be a socket screw that would be rather difficult anyway. Most would prefer to spend time working on more interesting aspects of the project which may or may not need screw cutting. As a for instance, some might want to make rather than buy T bolts. They want these to hold something down while working on it. They could cut all of the threads and even make the nuts but most would want to get on and use them so would buy suitable taps and dies. I suspect many would just go out and buy the lot. The original poster wants to use his taper turning attachment. Form accuracy is easier these days due to the availability of carbide screw cutting inserts. Chasers used to be used along with various types of form tools when accuracy is needed. Sometimes, eg a mic thread, it's best to screw cut and finish off with a die, same with the hole it runs in. Here form and pitch accuracy is needed and hopefully the tap and die pitches are correct. Lathe lead screws wear. If some one wants to learn to screw cut, it's best to just chuck a piece of mild steel and practice cutting threads. A suitable size would be one to match the spindle nose of the lathe that's being used as a back plate may have to be made some time. :-) In my case, a long time ago, it was 4 ft of 6 inch dia steel. I cut 4 tpi thread forms lathe style bs and un followed by square, acme and buttress. The acme was done in 2 ways - direct and then by modifying a square thread. I ground all of the tools by hand. As if it's possible to see a few 0.0001 in. gaps when a tool is held up against the gauge and viewed against a light, I know the form is that accurate. Lathe style? When cutting a BS thread for instance, classically a pointed tool is used. The work is turned to the required od minus the radius on the end of the correct thread form. A calculation is then done to see how far the threading tool needs to go into the work to make the flank angles of the thread correct. If the work needed to be particularly accurate, the actual position of the flanks would be measured with wires and a micrometer, 2 wires on one side and 1 on the other. In that case, or more when a thread is being fitted to another part, a small radius can be added to the end of the tool providing that it's smaller than the correct form radius. That can be often done by eye with a 10x loupe and a rule. The radius can also be estimated and used to modify the pointed tool depth avoiding the use of wires but those are needed for ultimate accuracy. Internal threads are handled in the same sort of fashion but measuring them accurately has its problems. Once someone has mastered screw cutting, a useful 1st project would be a replica spindle nose for use when making back plates. This can be used to get the register and the thread to the correct size. John ------- [SherlineCNC] Re: Thinking of anodizing the sherline aluminum tooling plate Posted by: "Stan Stocker" skstockerx~xxcomcast.net Date: Sat May 12, 2012 6:55 am ((PDT)) > The helicoil idea is interesting. I'm wondering what is often used > to secure it in the hole? Greetings, Helicoils lock in place when you install them. You install them with the installation tool and snap off the tang. All done. Here's the word from the horses mouth: http://www.helicoil.com.sg/HeliCoil-Screw-Thread-Insert-Types.htm I haven't heard of anodizing causing warping, just some dimensional changed from the coating, which you already know about. You mentioned that you had a CNC table. Does this mean you have a CNC mill, or just a CNC ready mill? Drilling a grid of holes in a piece of surplus aluminum jig plate is pretty easy on a CNC machine. In reality, as the hole locations are not critical, you can make tooling plates on a drill press with a fence and a batch of short wood strips as thick as the hole spacing. Tapping can be sort of a chore, but gun taps can be run in using a cordless drill. Aluminum jig plate shows up surplus now and then, it's precision ground, hard, and flat. Wonderful stuff, but very expensive to purchase new. Have fun, Stan ------- Re: Thinking of anodizing the sherline aluminum Posted by: "Marty Swartz" marty.swartzx~xxgmail.com Date: Sat May 12, 2012 7:26 am ((PDT)) On Hellicoils - They are indeed held in by spring tension. One prepares the hole in the plate by drilling and tapping with an oversized drill and tap. The coil has a tang at the front end, which is grabbed by a provided insertion tool that winds the the coil up into a slightly undersized state, which gets "dragged" into the prepared thread. After insertion, the tang gets broken off, and the coil holds itself in place by spring tension. Works great. For the relatively small loads we are talking about here, it's a great solution. Kits come with the necessary drill, tap, and insertion tool and tang-breaker, along with a quantity of inserts. Additional inserts are available separately and quite economical. We've spent more time describing this than it will take to execute the work. Try it, you'll like it. ------- Helicoils -- from tooling plate thread [SherlineCNC] Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sat May 12, 2012 4:46 am ((PDT)) Good Morning All, I spent my career at NASA, building spacecraft. Every tapped hole in aluminum, in every flight project I ever saw, had a helicoil or other type threaded insert. I've installed thousands of them. An insert significantly increases the strength of a bolted structure, and allows multiple re-assembly without wear in the aluminum. They allow the fastener to be torqued higher, increasing stretch and clamping force. They also are available with self-locking features. A few points: Take care to select the correct tap for the particular insert and type of material. Tap drills are standard number or letter sizes. If the hole is not properly drilled and tapped, the insert may jam with the tang broken off. Major PITA. Practice installing in scrap meterial before you risk a valuable part. Don't use stainless steel inserts with stainless steel screws -- they will gall and jam. For the sailors out there -- stainless and aluminum is a bad mix in a salt water environment. Use bronze inserts, or paint the outside of the insert with zinc chromate primer and install while the paint is wet. All that said, the practicality for the home shop is questionable. In aerospace, where strength to weight, and reliablity are at a premium, they are invaluable. But, except to repair a stripped thread, I've not used one since I retired. As for mill plates: if I need to drill or mill to a depth that would damage the mill bed or plate, I use a piece of sheet ABS plastic under the part to take the hit. 1/8 inch ABS is cheap. Make a bunch of cover plates for your mill plate with a matching pattern of clearance holes. Throw away when you run out of flat surface area. Best, David Clark in Southern Maryland, USA ------- Re: Helicoils -- from tooling plate thread Posted by: "jamboacn" jambomacx~xxsbcglobal.net Date: Sat May 12, 2012 10:34 am ((PDT)) "ABS sheet" recommendation should be understood and attended to accordingly. IANA DANGER! "Acrylonitrile-Butadiene-Styrene (ABS) uses a number of hazardous chemicals. These include butadiene and styrene and acrylonitrile. Acrylonitrile is highly toxic and readily absorbed by humans by inhalation and directly through the skin. Both the liquid and its vapor are highly toxic. Acrylonitrile is classified as a probable human carcinogen as are styrene and butadiene." GIYF [Google Is Your Friend] John Adam Libertyville, IL ------- Re: Helicoils -- from tooling plate thread Posted by: "Ron Thompson" ronx~xxourcadguy.com Date: Sat May 12, 2012 5:19 am ((PDT)) I use MDF or aluminum plate for this. MDF is cheap but the aluminum compresses less for a hard to hold part or where tolerances are tight. Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA Think, Draw, Print. 3D printers ROCK! http://www.plansandprojects.com/My%20Machines/PrusaMendel2012-1/ http://www.plansandprojects.com My hobby pages are here: http://www.plansandprojects.com/My%20Machines/ Visit the castinghobby FAQ: http://castinghobbyfaq.bareboogerhost.com/ ------- Re: Helicoils -- from tooling plate thread Posted by: "jamboacn" jambomacx~xxsbcglobal.net Date: Sat May 12, 2012 10:37 am ((PDT)) " I use MDF" Another caution: "MDF can be dangerous to use if the correct safety precautions are not taken. MDF contains a substance called urea formaldehyde, which may be released from the material through cutting and sanding. Urea formaldehyde may cause irritation to the eyes and lungs. Proper ventilation is required when using it and facemasks are needed when sanding or cutting MDF with machinery. The dust produced when machining MDF is very dangerous. Masks and goggles should always be worn at all times. Due to the fact that MDF contains a great deal of glue the cutting edges of your tools will blunt very quickly. MDF can be fixed together with screws and nails but the material may split if care is not taken. If you are screwing, the screws should not be any further than 25mm in from the edge. When using screws always use pilot holes. Urea formaldehyde is always being slowly released from the surface of MDF. When painting it is good idea to coat the whole of the product in order to seal in the urea formaldehyde. Wax and oil finishes may be used as finishes but they are less effective at sealing in the urea formaldehyde" John Adam Libertyville, IL ------- Re: Helicoils -- from tooling plate thread Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sat May 12, 2012 11:17 am ((PDT)) You cannot make assumptions about the toxicity of a compound from its ingredients. Sodium and clorine are both deadly. Sodium cloride is table salt. ABS is one of the most common engineering plastics. Most of the plastic in your home is ABS. I wouldn't eat it, or smoke it -- but then, I wouldn't eat aluminum, or smoke anything. On the other hand -- there is some controversy about the use of plastics in food containers. And many substances used in machining and industry certainly are hazardous in many ways. Good shop safety practice includes an awareness of these factors and due diligance in mitigating them. DC ------- Re: Helicoils -- from tooling plate thread Posted by: "jamboacn" jambomacx~xxsbcglobal.net Date: Sat May 12, 2012 11:28 am ((PDT)) I made no assumptions.... Vaporize some table salt in a confined area, breath deeply for an extended period, then get back to me. I don't cut (which always means vaporizing constituent materials) ANY "plastics" without ensuring negative air flow. And some will still insist Darwin was an idiot.... ------- Re: Helicoils -- from tooling plate thread Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sat May 12, 2012 11:40 am ((PDT)) Goodness John, what are you getting all snarky about? There's no dispute here that I can see. I was not dissing your post. You can certainly drown in salt water. Doesn't mean avoid it entirely. Same with plastic. Best regards, DC ------- Re: Helicoils -- from tooling plate thread Posted by: "jamboacn" jambomacx~xxsbcglobal.net Date: Sat May 12, 2012 11:49 am ((PDT)) Apologies for snark - lack of coffee and "highly evolved" client calls this morning (errr- afternoon) have me at sixes and nines. Really just wanted to encourage folks to not huff vaporized plastics. Best, JB ------- Re: Helicoils -- from tooling plate thread Posted by: "a3sigma" dcclark111x~xxcomcast.net Date: Sat May 12, 2012 12:21 pm ((PDT)) Understood, thanks, I know the feeling. Peace, goodwill, safe and happy machining to all. DC ------- I broke a die [taigtools] Posted by: "StlBill" stl.billx~xxyahoo.com Date: Mon May 21, 2012 10:11 am ((PDT)) I have been running a Taig lathe for about 30 years (1982ish). I am not very good but I do have fun. I hate it when I make a dummy mistake. I wanted to thread a 1/8" ss rod (annealed) 5-40 for a 1/4". Easy, huh? No big deal. When I was loading the die into the tail-stock die holder, the die didn't seem to be square. I removed the die and wiped it down. I wiped out the die recess in the holder and tried it again. It still didn't look quite right. Since this was such a simple job I had done many times before, I just tightened the set screws a little more (a lot more!). I was having trouble getting the the thread to start so I removed the die again. It came out in two pieces! 5-40 is a common thread size for my projects and I had used this split die for more than a dozen years. When I examined the die-holder and die, I suspect I failed to line up the set screws of the die-holder with the dimples in the die. I mention it only because I am reminded by these kinds of errors to slow down. When something doesn't look right, it probably isn't. The couple of minutes I saved not listening to that inner voice ("Something is not right!!!") cost me several days of waiting for a replacement die to arrive. This was a cheap mistake and easy to correct. My lesson for the day (if you wish to accept it) is to slow down, keep your work clean and be methodical. It is probably the first day lesson in machine shop. I confess to being to too much of a hurry to start carving metal to mess with such basic stuff. Take care and have fun. Bill ------- Re: I broke a die Posted by: "ED MAISEY" holmes_ca_2000x~xxyahoo.com Date: Mon May 21, 2012 11:33 am ((PDT)) Some good advise there Bill. A little trivia Bill, it's best to spread open the die for the first run. You can always take a second cut to size it, that's providing the die doesn't have an adjustment screw for setting the die, Edmund ------- Re: I broke a die Posted by: "alighazizadeh" alighazizadehx~xxaol.com Date: Mon May 21, 2012 4:51 pm ((PDT)) Hi Bill, I am glad that I am not the only one whom suffers from these sorts of mishaps. My workshop is in my very small English loft and as I am only just about 5'10" in height, I'd still have to be careful as to where I stand up straight in the busy loft. I am at pains at times to make sure that I keep things tidy and clean; at times this looks like a losing battle hence, my sympathies. Regards, A.G ------- Re: I broke a die Posted by: "Don" Donx~xxCampbell-Gemstones.com Date: Mon May 21, 2012 6:56 pm ((PDT)) Bill, I'll probably file this away with some other stuff that couldn't happen to me. So this is to inform you that you have an "I told you so" deposited and drawing interest. I'm sure that Don's Regional Bank of Dumb Stunts will make good on the note. On the bright side, it wasn't a tap broken off in a project that you had a hundred hours into. Don ------- Date: Tue, 21 Aug 2012 14:43:18 +1000 From: Mick Dowling Subject: [OldTools] How to use a screw plate. GGs I have a small screw plate, the business end being about 75mm 3 inches long. Pic here: http://tinyurl.com/8bo8qj9 The screw sizes are tiny, and I can't figure out how you would use it without snapping the screws off. I've never used a screw plate of any size, so am completely clueless on this subject. So my question, is the screw plate held stationary and the screw is somehow turned into it, or is the screw held stationary and the screw plate turned. Either way, if I were doing it there'd be a lot of busted and bent screws. Mick Dowling Melbourne Member, Hand Tool Preservation Association of Australia Inc. ------- Date: Tue, 21 Aug 2012 11:11:34 -0400 From: "Cliff Rohrabacher Esq." Subject: Re: [OldTools] How to use a screw plate. I'm guessing you have a jeweler's screw plate. The thing works like any other. It just requires a delicate hand. ------- Date: Fri, 24 Aug 2012 08:40:21 +1000 From: Mick Dowling Subject: Re: [OldTools] How to use a screwplate. Hello Cliff. So how do you use a screwplate? I agree, it's probably a jeweller/watch/clock makers tool. But I still don't understand the method of use. How do you hold a tiny rod of metal that you plan on turning into a bolt, and then either turn that tiny rod somehow into the stationary screwplate, or turn the screwplate around the stationary tiny bit of rod, and not snap the rod? How do you hold it square? Is this something that takes place with the aid of a lathe, or a drill press? I reckon most screwplates that I've picked up over the years have at least one snapped off bolt. Can the spokesperson for the Screwplate Users Interest Sub-group please chip in here with an answer? Mick Dowling Melbourne Member, Hand Tool Preservation Association of Australia Inc. ------- Date: Fri, 24 Aug 2012 08:26:58 +0800 From: Peter McBride Subject: Re: [OldTools] How to use a screwplate. Mick, The rod for making a screw is the diameter of the head or larger. It is turned in a lathe until the shank is the right size. Then the screw plate can be held up to the taper of the shaft and the lathe manually turned. Or the rod taken from the lathe and clamped in a pin vice and turned in the screw plate which is held in the other hand. Accuracy with respect to square, is experience, and is just done by eye. There is a brass collet mini lathe arrangement for holding the threaded end, and that can be used to hold the screw while the slot is cut and the head is polished with emery or a burnisher by running the palm of the hand back and forth over the spindle. It is then ready for blueing. Here is that tool. It is held in the vice with the block on the base. The burnisher is held against the rest on the bottom one in the picture, and the other one is missing the rest. http://www.petermcbride.com/watchtools/2_collet_lathes.jpg Here is a picture of a steel LH tap I made. I used a small tap holder to hold the rod, which was a softened needle file shank. http://www.petermcbride.com/planemaking/images/LHtap1.jpg From this page... Must finish that one ... http://www.petermcbride.com/planemaking/miniature.htm Regards Peter ------- Date: Thu, 23 Aug 2012 20:12:21 -0500 From: John Holladay Subject: Re: [OldTools] How to use a screwplate. It will be the first number one plane that is actually worth the cost. At least in terms of the materials it is made from. Doc ------- NOTE TO FILE: For those who are not aware, the Stanley Number One plane is the smallest plane in the line that has the form and function of what most of us think of when we picture a woodworking plane. It was intended for small hands as for children and schools. When governments had scrap metal drives for the WW2 war effort, it is likely that these small and relatively impractical planes (at least from an adult's perspective) were frequently contributed and thus have become exceedingly rare and valuable. Peter McBride has made a brilliant miniature including precious metals that is indeed valuable by any measure. Another woodworker (sorry I can't remember who at the moment) also made a life size replica and then tortured it. Hence imagine the shock of a visiting woodworker to see a No. 1 drilled and nailed to a drawer front as a drawer pull. Tears. Lots of tears. Hmmmm... Every hobby or pastime has its own version of a rare and expensive tool or accessory ... we could make our own clever approximation and torture it ... and our friends ;-) ------- tips on tapping? [taigtools] Posted by: "juangelt" juangeltx~xxyahoo.com Date: Wed Oct 24, 2012 2:26 pm ((PDT)) This is about the most tedious part of any project, to me- spending a day tapping holes makes the day go v e r y s l o w l y. Mostly I do 6-32 and 10-32 in aluminum and brass. I'm always fearful of breaking one of the 6-32 taps inside the hole. My EDM machine isn't done, so that kind of faux pas is really a grand gaffe. Does anybody have tips on getting the job done without the dramatic boredom? ------- Re: tips on tapping? Posted by: "Nicholas Carter and Felice Luftschein" felicex~xxcasco.net Wed Oct 24, 2012 2:50 pm ((PDT)) Get some high quality "gun" or spiral point taps if they are through holes. For #6-32 using form taps reduces the risk of breaking as well (as it does with #10, but the aren't as weak as the 6-32). Form taps are also good for blind holes. They use a different tap drill size and cold forge the thread rather than cutting. ------- Re: tips on tapping? Posted by: "Paul J. Ste. Marie" taigx~xxste-marie.org Date: Wed Oct 24, 2012 9:57 pm ((PDT)) I would think the form taps would be more likely to break on through holes, since they require higher torque. Blind holes, where chip buildup is a problem, are a different story. One of the machine shop books I have recommends designing stuff to use 6-40 fasteners instead of 6-32. The threads are better proportioned to the diameter (13% greater cross-section if I didn't botch the calc). I imagine an M3.5 would also be a good alternative -- ISTR [I Seem To Recall] that metric fasteners tend to have finer threads than their UNC equivalents. ------- Re: tips on tapping? Posted by: "Boman33" boman33x~xxvinland.com Date: Wed Oct 24, 2012 2:58 pm ((PDT)) I sometimes do a lot of tapping and here are a few points: 1. If not absolutely needed because of thin material, use a little bigger drillbit and get less % thread. It does not matter if the tapped material is thick, the thread will be strong enough. 2. Use "Gun" taps when possible. 3. Good lubrication 4. I often power tap either: a. Using the mill on low RPM and carefully watch when to reverse it. b. A tapping head (a great way but not cheap) c. A regular hand electric drill. I did a ľ" aluminum plate with about 400 1/4" X 20 tapped holes that way. 5. If delicate, I use a tap guide either in the mill or a separate one to make sure the tap goes straight. I literally do not remember the last time I broke a tap. (Maybe bad memory...) Bertho ------- Re: tips on tapping? Posted by: "Jake Horky" jacob.horkyx~xxgmail.com Date: Wed Oct 24, 2012 3:10 pm ((PDT)) Good tips. I really don't care for drilling and tapping either... Lately I've been using high quality taps, Tap Magic, and a cordless electric drill to help ease the boredom on #8s and bigger. I feel more confident that the taps won't break when they cost a little more. I also picked up an old, solid tap guide which speeds things up, especially when backing the tap out since I can quickly spin the handle with one finger. ------- Re: tips on tapping? Posted by: "Will Schmit" anchornmx~xxyahoo.com Date: Wed Oct 24, 2012 3:23 pm ((PDT)) I use a cordless drill and set the clutch to 3 and let the clutch hammer the tap around. A double ended tap handle is helpful too (it tells you by tactile response if you need to crank up the clutch). ------- Re: tips on tapping? Posted by: "ED MAISEY" holmes_ca_2000x~xxyahoo.com Date: Wed Oct 24, 2012 6:11 pm ((PDT)) Juangelt: If you are manually tapping, no talking or conversations, no music or television, complete silence and concentration; that will help evade an accident. Edmund ------- Re: tips on tapping? Posted by: "Low Compression" editorx~xxmodelenginebuilder.com Date: Wed Oct 24, 2012 8:59 pm ((PDT)) I tapped 1500 holes 6-32 in 306 SS without breaking the tap. I used a tap made for SS (German made and specially coated) and no lube. I did it in my Bridgeport in low gear, just about as slow as the mill would run. I would bring the quill down until the tap dug in and then let the tap pull the quill down until I wanted to reverse the mill. Do remember that taps have a definite life and most manufacturers stop using a tap before it reaches the maximum number of holes for which it is designed. That's why you can buy batches of used taps for so little. They are ready to break. ------- Re: tips on tapping? Posted by: "Pierre Coueffin" pcoueffinx~xxgmail.com Date: Wed Oct 24, 2012 9:50 pm ((PDT)) The problem with a broken tap is mosty that it usually breaks off flush with the surface of the work piece, or below the surface. This leaves you trying to grip the flutes inside the hole to work it loose. This tip from Popular Mechanics is pretty slick: http://books.google.ca/books?id=5dgDAAAAMBAJ&lpg=PA207&pg=PA225&re dir_esc=y#v=onepage&q&f=false By creating a weak area higher up the shank, if you overstress the tap and snap it off, it should leave you with enough shank sticking out to put some vice grips on it and work it loose. ------- Re: tips on tapping? Posted by: "Ian Newman" ian_newx~xxyahoo.com Date: Thu Oct 25, 2012 8:52 am ((PDT)) Hi. Assuming you have three taps for each size (in the UK we call them taper, second and plug -- different terms are used in other parts of the world). If you are tapping small threads into blind holes, start with the second tap not the taper tap -- there is a risk that the taper will bottom on a blind hole and and as the thread at the entrance to the hole will only be partly cut it will strip very easily. If you have a set of taps and dies with only two taps of each size, they usually leave out the second tap so it may be worth buying one. I would always recommend using Carbon Steel rather than High Speed Steel taps for the following reasons: 1) They stay sharper for longer (HSS is much better than CS at high temperatures, but at the normal temperatures encountered in tapping, CS wears better than HSS). 2) They cost less (about 1/2 to 2/3 the price of HSS in the UK). 3) You can soften them at a sensibly low temperature to make it easy to drill out any broken ones (it happens to us all). Unless you are doing heavy machine tapping in a production environment, the temperature of the tap does not get high enough for you to see the benefit of HSS. There is only one reason for choosing to use HSS taps and that is due to the manufacturing process rather than the material properties: CS taps are made by cutting the blank using a master die, grinding the flutes, then heat treating the tap to harden it. Although the heat treating is done under careful control, it will introduce some small amount of distortion. This means that you will have problems if you try to re- sharpen the tap in a tool and cutter grinder. HSS taps are made by grinding the threads into a fully hardened blank. This means the thread is always accuate to the centre of the tap (and is likely to be a more accurate thread generally -- but QC comes in here so this is a theoretical point). This means you can resharpen the tap by mounting it on the centres at each end. The inherently more accurate thread on HSS taps may be important if you make micrometers, but otherwise all taps are made to some sort of standard of accuracy so this is not something I worry about. As for resharpening -- I do not have a T&C grinder so I'm not concerned with this activity (the best my taps get is the occasional touch with a little slip stone). In fact I grind the centre point off the end of most of my plug (bottoming) taps anyway, so they can reach as far down blind holes as possible. All the best, Ian ------- Re: tips on tapping? Posted by: "ED MAISEY" holmes_ca_2000x~xxyahoo.com Date: Thu Oct 25, 2012 6:23 pm ((PDT)) Ian, I recently did a search for carbon taps (for the amount of use they get as a hobbiest) they will probably last a lifetime, (tongue in cheek). All my ME taps are carbon, and as you say cheap at half the price. If I had the choice all my taps would be carbon. Edmund ------- Re: tips on tapping? Posted by: "Pierre Coueffin" pcoueffinx~xxgmail.com Date: Fri Oct 26, 2012 12:23 am ((PDT)) Back on topic, if I'm threading something that seems inordinately tough (like a weldment of random scrap steel) I sometimes tap using a smaller diameter tap first that uses the same thread pitch. For example, if you run an 8-32 tap into a hole that is sized for a 10-32, then follow it with the 10-32 tap, it goes much easier. The 8-32 tap makes about a 10% thread, so it is not really stressed, but when the 10-32 goes in, it has a nice pre-cut track to follow. I got the idea from some high-priced tapping sets I once read about that use 3 taps to produce a threaded hole. Two progressively larger undersized taps, then an on-size finishing tap. ------- Re: tips on tapping? Posted by: "cary brief" caryncbreeefx~xxyahoo.com Date: Fri Oct 26, 2012 4:06 pm ((PDT)) As a former machine shop owner that did production tapping on ss bearings down to M 0.75 as well as lots of other tapping and od threading coolant/ lubricants are super important. I think we used moly lube on non-cnc applications. It is thick and worked wonders, even on hard to tap and thread stuff with geometric die heads. When tapping on the lathe I use a floating guide into the back of a tap holder. ------- Re: tips on tapping? Posted by: "Don" Donx~xxCampbell-Gemstones.com Date: Sat Oct 27, 2012 10:54 am ((PDT)) A couple years back, there was a garage sale of machinist tools. I picked up a Prociner 2E tap head with a full set of collets for $50. It is sweet. The issue though is that it takes up a lot of height. My 13" bench drill just had enough height to work. My little drill press couldn't handle it, shank size (1/2") and length were both out of range. I started looking at the Tapamatic and STM heads. I ended up picking up a nice used STM YSN7 head with a range of #0 to 1/4". The Procunier is right hand thread only, but the YSN7 works for either rotation. I had hoped to be able to use it on my Taig mill, but again even with the shorter length, there isn't enough throat to handle anything a inch above the table. I'm making a steel dovetail plate 8" in length which will allow the tap head to work. The issue with a mill though is providing a constant coordinated down pressure so the tap doesn't start and stop, or is overfed and results in a broken tap. The hand feed of the drill press is a better fit, but you then lose the precision of locating the hole. Something else to point out, you have to have the work clamped because it requires an up pressure to engage the reversing mechanism and if the work is not firmly attached to the table, it will try to lift, generally resulting in a broken tap at best or cracked knuckles from the work turning. The up feed is faster than the down speed. The Procunier is 1.6 to 1 in reverse, while the YSN7 is 2 to 1. I think the Tapamatic 30x is the same as the YSN7. Last, here is a link to the Procunier Tap Drill Chart showing the tap drill sizes for both cut and roll threads as well as the speed for different metals. Note the speed they recommend. My YSN7 has a recommended speed of 1500 rpm. http://www.rockford-ettco.com/Default.aspx?tabid=1488 ------- [Broken Tap Removal] Oh S*!t [myfordlathes] Posted by: "alan4227" a.j.moorex~xxbtinternet.com Date: Sat Dec 29, 2012 10:26 am ((PST)) Does anyone have a foolproof method for getting a broken 8BA tap out of a piece of stainless steel? Naturally it has broken off flush with the surface, so there's nothing to grip. It's my own fault. I only have a single 8BA plug tap (or rather I had), but I've used it succesfully many times to tap into brass, bronze and mild steel. I drilled the holes with the approved 1.8mm tapping drill, but I obviously did not make enough allowance for the greater toughness of the stainless steel. The piece is the end cover for the steam cylinder on a stationary engine I'm building. The 8BA holes take studs which hold down the stuffing box gland around the piston rod. Tapping these was the last operation on the cover (isn't that always the way!). If the worst comes to the worst I can rotate the piece by 60 degrees, drill three new holes, buy myself a full set of 8BA taps and try again. The trouble is that I will always see the other three holes sitting there. Regards, Alan ------- Re: Oh S*!t Posted by: "Robert Mitchell" rmm200x~xxyahoo.com Date: Sat Dec 29, 2012 11:21 am ((PST)) Try this one: http://modelenginenews.org/meng/edm/index.html Myself, I would try Nitric acid first, since stainless is slow reacting, but the spark EDM is something I always wanted to build. Be careful with acid - Nitric loves flesh... Robert Mitchell ------- Re: Oh S*!t Posted by: "Barry Kneller" bkba09515x~xxblueyonder.co.uk Date: Sat Dec 29, 2012 11:33 am ((PST)) Alan - a Diagrit Hard Cut drill will do it (if you can grind a tiny 'centre pop' for the drill to start in) - I don't think they make 'em any more and the smallest I have is 1/8", which you're welcome to borrow, but that'd mean you have to fit a threaded insert or even a helicoil, if they do them that small? Maybe another member has a 1/16th or 3/32 Hard Cut drill that'll do it. PM me if you want to borrow mine. ------- Re: Oh S*!t Posted by: "john baird" alexandra.leavingx~xxyahoo.co.uk Date: Sat Dec 29, 2012 1:33 pm ((PST)) A spark erode unit, would be the way to go, but where do you find one of those in the New Year holiday period? Regards jb ------- Re: Oh S*!t Posted by: "gnuoyb" gnuoybx~xxgmail.com Date: Sat Dec 29, 2012 2:44 pm ((PST)) If your tap is carbon steel then vinegar will do it but it will take at least a couple of weeks. I had a similar problem on a small SS item last year, popped it in a jar with the vinegar, kept it in a warm place (anywhere here, I live in the tropics!) and pushed the remains of the tap out with a scriber. If the process is working you will see bubbles rising from the dissolving tap. If your item is too large to fit in a container you will have to be a bit more inventive. Try to get the vinegar at both sides of the tap. I suspect this fix will not work on HSS taps. Good luck! ------- Re: Oh S*!t Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk Date: Sat Dec 29, 2012 5:27 pm ((PST)) Hi Alan, I'm with Robert, Nitric acid is a way to go. If you are wondering in these paranoid H&S days where you can get it, try a gun/shooting shop as it is used to clean cartridge cases. Ask for "cartridge case cleaner". I have used it to dissolve a M2.5 tap that I rather foolishly snapped in some Aluminium. It only took an afternoon to work, leaving a soft black sludge where there was once a tap. I would also highly recommend that small taps are only used in a tapping stand or some other form of rigid support; using free hand is asking for trouble. CJ(UK) ------- Re: Oh S*!t Posted by: "Orologe" knibbx~xxastro5.com Date: Sat Dec 29, 2012 6:17 pm ((PST)) A saturated Alum solution will eat away steel. I knew a watchmaker who used toilet bowl cleaner to eat away broken screws. Ralph ------- Re: Oh S*!t Posted by: "Robert Mitchell" rmm200x~xxyahoo.com Date: Sun Dec 30, 2012 12:12 am ((PST)) I must be running short on projects - I just joined the Yahoo home built EDM group: http://tech.groups.yahoo.com/group/EDMHomeBuilders/?yguid=177091715 Robert Mitchell ------- Re: Oh S*!t Posted by: "Kevin" tadpolex~xxbtinternet.com Date: Sun Dec 30, 2012 3:47 am ((PST)) As they've said, any acid will do it eventually. The clockmaker's classic way of removing taps from brass was to boil it up in a solution of alum (aluminium sulphate), but that was in the days when every household had some alum in the kitchen and every clockmaker had it to hand for removing flux residues. The process goes much faster if it's warm, or hot. There's a residue left behind, and it helps if you get that out of the hole from time to time. You often find that after a while you can pick the remains of the tap out with a bit of wire; you don't always have to wait for it all to be dissolved. No guarantees at all that your piece of stainless will be fit for purpose afterwards though ... depends on the particular alloy. Other "helpful" comments .... consider scrapping and remaking (?). Make a core drill to cut it out. If it is not in a blind hole you might be able to punch it through. Kevin, NW England, UK ------- Re: Oh S*!t Posted by: "werealldoomed" sardinesarniex~xxyahoo.com Date: Sun Dec 30, 2012 4:08 am ((PST)) CJ. That's a pretty neat trick. What effect does the acid have on the aluminium, is there discolouration, for example? You think it would work for bigger taps, M8 maybe? I guess it would just need more acid and longer time. Thanks. Kind regards ------- Re: Oh S*!t Posted by: "c j.s" callinicus1953x~xxyahoo.co.uk Date: Sun Dec 30, 2012 8:29 am ((PST)) Hi 'Doomed, It had no noticeable effect on my Al, but doing a test on any new job would be a wise move. Obviously the larger the piece to be eaten the longer it will take, but all you need to do is remove enough of its outside to get the core out; you certainly would not need to dissolve the whole thing. For those interested I got my case cleaner from Delway Technical Services at one of the ME exhibitions many years ago. Unfortunately they no longer go to shows but are still in business I believe. They used to sell metal blacking kits and ultrasonic cleaning tanks, thinking of which, I wonder if one of those tanks would speed up broken tap dissolving? On the subject of EDM, for those in the UK, at the upcoming exhibition at Ally-Pally (Jan 18-20) there is a good chance that SMEE will have one or two home built ones on their stand. CJ(UK) ------- Re: Oh S*!t Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Sun Dec 30, 2012 5:39 am ((PST)) Many thanks for the interesting and useful advice. Now where is the nearest gunsmith? Thinks - what effect will nitric acid have on my stainless steel piece? Better try it on a bit of scrap first. Regards, Alan PS. I was using a tapping stand, but I think my mistake was to use the standard 1.8mm tapping drill. Next time I will use 1.9 or maybe even 2.0 and start with a taper tap. ------- Re: Oh S*!t Posted by: "David Ingram" davidi1107x~xxyahoo.co.uk Date: Sun Dec 30, 2012 5:53 am ((PST)) Hello Alan Do not worry about the nitric acid and stainless steel (unless it's lower than grade 304 - no experience outside 304 & 316); in previous life we used 15 to 20% Nitric acid to passivate the internal surfaces of stainless steel pipework to protect it from corrosion. Stainless steel naturally passivates but using nitric speeded up the process and yes the nitric would remove non stainless steel surface inclusions such as mild steel grinding dust. We would also used citric acid where the disposal of the nitric would prove troublesome, but citric took much longer to work. Regards Dave ------- Re: Oh S*!t Posted by: "Steve T" steve.talbotx~xxtiscali.co.uk Date: Sun Dec 30, 2012 12:58 pm ((PST)) Hi Alan. Found in a box of oddments I purchased at auction were a number of tap removal tools. They consist of three arms, a central shaft and handle, and a screw ferrule. The arms are poked down the tap flutes (obviously you choose a set that fit the tap) and the ferrule tightened down to clap the arms. The whole unit is then rotated unscrewing the tap. Well at least that's the theory, haven't tried them yet!! You could probably make one up using either silver steel or piano wire for the arms. Hope this may help. Regards, Steve T ------- Re: Oh S*!t Posted by: "hooyaicon" hooyaiconx~xxyahoo.co.uk Date: Sun Dec 30, 2012 2:32 pm ((PST)) This is absolutely no help for you at all, but... I snapped an 8BA tap off in a bit of cast iron that I had several hours invested in - the tapping was the last operation. At the time, I was learning to TIG weld at Norwich City College, and the instructor was 'moonlighting' from Vacweld in North Walsham. I took it in to the next night and asked him if they had an EDM machine, and if so could he possibly.... He said he'd see what he could do. About ten minutes later, he appeared at my side with the broken stub of tap in one hand and the bit of cast iron in the other. He'd welded a tiny 'handle' of stainless filler rod to the tap, and screwed it out. I kept it for a couple of years, but then lost it. It was rather small. John -------- Re: Oh S*!t Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Fri Jan 11, 2013 4:53 am ((PST)) Update on my broken tap. The only cartridge case cleaner I could find online turned out to contain, not nitric acid, but phosphoric acid, glycolic acid and, wait for it, dodecylbenzenesulfonic acid. It took a week to dissolve my tap out, as against what might have been a few hours with nitric, but it got there in the end. My cylinder cover is now tapped 8BA all round and I am a happy bunny. Many thanks for all the valuable advice. Regards, Alan ------- Re: Oh S*!t Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk Date: Fri Jan 11, 2013 9:33 am ((PST)) > dodecylbenzenesulfonic acid It's a wetting agent (detergent) to help the liquid get everywhere. Good news; thanks for updating us. David Littlewood ------- Re: Removing a broken screw [myfordlathes] Posted by: "davetherave_11" davetherave11x~xxgooglemail.com Date: Wed Jan 16, 2013 5:01 pm ((PST)) "davetherave_11" wrote: > Good afternoon all, > Yesterday I discovered the bottom half of my ML4's clasp nut sitting > on the drip tray. I found that the retaining screw / pin had sheared > off below the level of the hole. > Can anyone suggest a way of removing the broken part of the screw? Thanks for the suggestions everyone. I'm not sure what route to take yet, I'm going to mull it over for a day or two. The general consensus is to use a screw extractor but I'm scared of snapping the thing! ------- Re: Removing a broken screw Posted by: "Edmund" wiggyracing2009x~xxtalktalk.net Date: Thu Jan 17, 2013 2:43 am ((PST)) Another way of removing that is by using a MIG Welder, something I've had to do so many times & which really works. Hold item securely in a vice or small clamp, clean up the bit to be removed using wire brush to scrub it clean, followed by a solvent cleaner to remove all traces of oil & grease etc. Allow to dry thoroughly, or use compressed Air to blow dry, them using MIG Welder to carefully spot one blob of weld at a time, blob outwards on the end of the steel threaded screw, until you have come out far enough to enable you to clamp a small fine pair of Mole Grip Pliers or similar onto that weld. (The broken stud MUST be absolutely clean & dry for the Weld to stick and hold.) If you are VERY careful with the accuracy of those weld blobs, and bear in mind that any welding spatter will not stick to the Alloy body of the Nuts themselves, then the generated heat of this process will also soak into those Nuts, expanding them greatly, allowing you to carefully undo and remove a previously very tight broken screw. Be VERY careful not to burn yourself! I use this trick all of the time, and it usually works for me... ------- Re: Removing a broken screw Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Thu Jan 17, 2013 3:40 am ((PST)) Dave, As someone has already said, this screw should not be rusty, just held in with gunge. It would be a good idea to clean things up with the most aggressive grease solvent you can find (I would have suggested carbon tetrachloride in the bad old days, but now I'm not sure what is available). Dry the piece thoroughly and then dunk it in WD 40 for a day or so. This will give the screw extractor the best possible chance. You need to be very careful with centre popping the broken screw and drilling the pilot hole for the extractor. If it wanders significantly off centre it will make the work of the extractor that much harder, as well as the risk of damaging the nut. A stub drill in a milling machine would be best, but the minimum would be a sturdy drill stand and machine vice. If you don't have a stub drill it might be worth sacrificing a normal drill to grind it down to a stub. The other thing to be aware of is the limit of shear strength of the extractor. They are pretty tough, but they can break if you are too enthusiastic, especially the small ones. It is better to put too little torque on it and have to think of another approach than heave too much and end up with a broken extractor to compound your problems. How much is too much? You just have to rely on common sense and engineering 'feel', I'm afraid. Regards, Alan ------- Re: Removing a broken screw Posted by: "Pete W." enwodex~xxyahoo.co.uk Date: Thu Jan 17, 2013 7:43 am ((PST)) Hi there, Dave, I realise that I've come into this thread a bit late. I have tried both the so-called 'Easy-Out' and the extractor that resembles the point of a left-handed drill. The left-handed drill would get my vote every time. Because of its sharp taper, the 'Easy-Out' tends to expand the stump of the screw in the hole and compound the problem. I'll try to find a photo of the type of extractor I mean. Look here: http://www.axminster.co.uk/axminster-screw-extractor-quick-ch ange-adaptor-and-bit-set-prod576720/ The top three in that set are the type I DO recommend - the bottom three I despise! You need a hand-held electric screw-driver or an electric hand drill but it must have the facility to rotate in reverse. A drill-press won't do because once the extractor bites and stops cutting, you have to keep the pressure on while the screw backs out. It looks from your photo as though your screw has broken off quite close to the surface of the half-nut and nice and square. That should help you start the extractor on the screw centreline. Good luck with it - please let us know how you get on. Best regards, Pete W. (aka 'Enwode') ------- Re: Removing a broken screw Posted by: "Haydut1200" haydut1200x~xxgmail.com Date: Thu Jan 17, 2013 7:46 am ((PST)) Have you tried the easy ways first, such as trying to tap it round with a centre punch? I have an old scriber that I use for small bolts. Is there room to get in with a Dremel or similar and cut a slot in the end, possibly using an engraving tool, to allow a screwdriver to be used? Getting some heat into it will generally help too. If it won't turn, tapping (not clouting:) with a small brass drift may help to loosen it. Personally, I wouldn't go near it with screw extractors. I must have removed hundreds of broken bolts over the years and what's needed most is patience. They all come out eventually. ------- Re: Removing a broken screw Posted by: "Stephen Voller" stephen_vollerx~xxhotmail.com Date: Thu Jan 17, 2013 8:44 am ((PST)) Hi Pete, I can see why you might might despise those easy outs. I have used easy outs on sheared engine studs, the easy outs I used had a much longer thread and taper and those in your Axminster link look like they are asking to fail for the very reason you stated. Makes you wonder if the product designer/manufacturer ever tried actually using them! kind regards Steve V ------- Re: Removing a broken screw Posted by: dennis.jewittx~xxtalktalk.net Date: Thu Jan 17, 2013 2:56 pm ((PST)) In the case of a flush break I usually get a bit of scrap strip and drill a hole in it to suit and then position hole over broken stud and fill the cavity with a mig welder - works well and the strip provides a shield. Dennis ------- Re: Removing a broken screw Posted by: "davetherave_11" davetherave11x~xxgooglemail.com Date: Thu Jan 17, 2013 6:06 pm ((PST)) Success!! I drilled a pilot with a stub drill in the drill press, then used an easyout (sorry chaps). The stud was not seized so it came out easily. Thanks everyone for the help. ------- ML7 graduated dial [myfordlathes] Posted by: "garthn444" garthnx~xxpbt.co.za Date: Mon Jan 28, 2013 7:38 am ((PST)) Hi. Can anyone give me the approximate diameter of the dial? I need to make one as per http://www.jeffree.co.uk/pages/ml7-cnc/part-2-files/myfordcncpt2.htm Also, aluminium should be good? And - the internal thread needs to be 1/4" BSF, and I can use a tap for this? (I've never tried tapping in the lathe, is this simple?) Thanks Garth ------- Re: ML7 graduated dial Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Mon Jan 28, 2013 8:47 am ((PST)) Garth, The purists will roll their eyes at this suggestion, but the easiest and safest way for a novice to tap in the lathe is to put the work in the headstock chuck, put the tap in the tailstock chuck, release the tailstock lock then push the tailstock up against the work while turning the chuck by hand. This ensures that the tap is square to the work, you can rewind to break the chip every so often and you can stop at any time if things get too stiff. Crude, but it works for me. Regards, Alan ------- Re: ML7 graduated dial Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Mon Jan 28, 2013 9:51 am ((PST)) On 28/01/2013 17:02, garthn444 wrote: > That's exactly what I was going to try, what is the purist method? Garth, I suppose the purist method (or at least the method closest to professional practice) would be some kind of tapping box with clutch. You run the lathe under power at low speed and push a lever to engage the clutch and prevent the tap or die rotating, but still able to slide longitudinally. Releasing the lever allows the tap or die to rotate freely. Hemingway Kits web site (www.hemingwaykits.com) shows a tailstock die box using this principle. In industry now they have much fancier units which can tap at high speed and auto-reverse, but I know very little about how they work. Regards, Alan ------- Re: ML7 graduated dial Posted by: "Paul Kennedy" clankennedy2004x~xxyahoo.co.uk Date: Mon Jan 28, 2013 11:45 am ((PST)) Having a large enough tap Wrench that will 'jam' or 'stop' against the bed will help prevent the tap from spinning on the dead center in your tailstock! Absolutely nothing wrong with using a tap for tapping! especially if it's a common size and you of course have the tap. Otherwise then thread cutting can be done but it can be tricky for a novice especially if the hole is blind. [later message: An adjustable spanner can be used in a pinch, depending.] ------- Re: ML7 graduated dial Posted by: "Kevin" tadpolex~xxbtinternet.com Date: Tue Jan 29, 2013 3:23 am ((PST)) Alan Moore wrote: > Crude, but it works for me. No no no, I disagree! Not crude at all, perfectly sensible. Well, I would say that, it's what I do too. Drill the hole from the tailstock then replace the drill with the tap to ensure that the hole is concentric with the axis. If I've drilled a hole for tapping using the drilling machine I normally do something similar ... put the tap in the chuck (workpiece is in a vice which is bolted to the table) and either turn the chuck by hand or put a bar type of tap wrench on the tap and use the chuck jaws, just loose, as a guide. Once it's started then take it out of the machine vice and into the bench vice to finish. Kevin, NW England, UK ------- NOTE TO FILE: I normally place a conversation into only one file here, the one I think most suitable for the particular topic. But the following discussion involved threading, and making an Atlas backplate [or any other brand's for that matter], and doing it with a boring bar. So it ended up in all three files. ------- Boring bar deflection [atlas_craftsman] Posted by: "geoffrey_in_siam_atlas_12in_3991" lovex~xxcvbt-web.org Date: Fri Mar 1, 2013 9:04 am ((PST)) We're making a backing plate for a 4-jaw chuck that I bought. I have to bore and thread 1.5" 8tpi threads. In making trial cuts on a test piece I've come across some puzzling things: Boring, we dialed in .150 on the cross feed and get .003" Threading, we dialed in on the compound rest .067" and got less than .010" Our boring bar is about 1/2" in diameter and 6" long. We mounted a linear dial indicator on the carriage and put the tip on the boring bar about 2" from the tool post. It seems that the boring bar is deflecting. When we set it up for real then we can grip it shorter. As we cut threads we think that the deflection will become greater. So, how can we measure to know when we have sufficient depth of thread? We don't have a male bolt handy. ------- Re: Boring bar deflection Posted by: jmartin957x~xxaol.com Date: Fri Mar 1, 2013 12:43 pm ((PST)) Use the largest bar that will fit the bore, and choke up on it so that you can cut just as far as you have to. No further. It should be sharp, and cutting. Not rubbing. Set it at center height or a bit above. Even if you do everything right, you'll still have to take a couple of "spring cuts", without changing the cutting depth, to take out the slop and windup in the system. Silly question, but you are taking out the backlash in both cross and compound feed screws in the cutting direction - outward - right? John Martin ------- Re: Boring bar deflection Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Fri Mar 1, 2013 12:45 pm ((PST)) if you are using the lathe that the chuck is intended for, you must EITHER make a copy of the spindle thread to check your thrdng progress, OR mount the back plate on a face plate ..then you can remove the face plate w/ back plate attached to check progress & then replace w/ out needing to pick up the thread...you are threading to fit, and NONE of the current depth of thrd specs will be correct ...you need to cut a V thrd, not some other stndrd.....you thrd to FIT on these spindles & on most home shop items ..if you doubt that, i will GLADLY sell you a 1-1/2 & 8 new tap for $20 + shpg. if you are inexperienced in boring /thrdng, PRACTICE on scrap first ... all boring bars flex ...just a question of how much, (doc, extension, diameter, grind etc) ....use a sharp pointed HIGH speed bit ....carbide cannot be made as sharp & requires more FORCE to cut, hence more flex... books show a rounded point ..forget it ...you want a sharp point w/ back rake & PLENTY side rake .for a real smooth finish; either angle the bit as flat as opossible w/ out chatter OR grind a 1/32 flat & take cuts under 5 thou (real smooth not needed to thread on)..these are light machines (plenty flex w/ using turning tools also) & until you really know where you are, 20 thou doc is plenty ...too fast a feed, & the bar will spring away ......stone your grind, makes a big difference....i use at least a 3/4 bar w/ bit on the end for 1-1/2 thrd.....i assume you are using a 1/2 bar w/ a small tool bit at the end???? you can still make it work, just lite cuts. fifty years ago w/ a 6x18 i bought the catalogue boring tools & cud not figure out for a LONG time why i cud not bore ...turns out the tools were not HARDENED ...experience wud catch that right away ...but as a beginner, it drove me nuts. oh yeah, dont forget to compensate for the back lash on your compound / x feed ....if you have not dialed it out, you can put on 20 thou or so & not move the bit !!!!!!! & just for the record i have cut more than a dozen back/face plates, finally on the last one i made a dummy spindle. best wishes doc ------- Re: Boring bar deflection Posted by: "cliff" kenx~xxucsp.com Date: Fri Mar 1, 2013 1:20 pm ((PST)) Make a male bolt first. You can check it as you make it by using a chuck or other 1.5 x 8 threaded part as go/no go. Then use the bolt as the go/no go for the back plate. The male part is much easier to make (external threads), and I doubt you will have great joy making the internal threads without having a go/no go test method. ------- NOTE TO FILE: The following tip provided by Doc is applicable for any number of situations, so I have repeated the wording to make it easier for search engines to find the variants that folks are looking for. In this instance the tip was placed in both the Chucks General and Threading files here. Increasing thread depth for a dog plate. Increasing thread depth for a back plate. Increasing thread depth for a face plate. Increasing thread depth for a chuck. Picking up a thread on a lathe. ------- increasing thrd depth on a dog plate [atlas_craftsman] Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Sun Mar 31, 2013 6:19 pm ((PDT)) FWIW .....fitting an ebay dog plate to a lathe in the garage, 28 feet from the basement shop & up a flight of stairs. d/plate was correct thrd (10TPI), but thrd was shallow & wud not start. i ground an ID spring caliper tip to 60 deg + so it wud not bottom out & used the 4 jaw backplate as a guage ...inserted the spring caliper between thrds & adjusted for right feel ...check against the d/plate & it was TIGHT (too lazy to cut a dummy spindle & didn't want to walk up stairs 1/2 dozen times checking the fit (81 yr old knees), so thought to use the spring caliper for gaging fit ...i have a factory OD spring thread caliper & it has been VERY useful, abt as good as the thrd mic. set up the lathe for 10TPI & internal thrdng.......engaged the thrd dial & the 1/2 nuts & adjusted carriage to an inch or two from the thrds, a bit beyond contact, & then fed carriage in to abt 1-2 thrds & shut the lathe off....VERY IMPORTANT TO GET THE SLACK OUT THIS WAY or you end up xthrdng ...NOW use the xslide & compound to center your bit in the hollow of the thrds using your eyes & TACTILE sense to center it up ...this is the only difficult part ....next set your xlide / compound dials to ZERO ...this is how to pick up a thrd after losing it all due to movement, jam up, wreck, whatever .... well worth knowing. two 5 thou cuts & two 3 thou cuts ...later i gaged w/ the spng caliper & it felt the same between thrds as on the chuck b/plate ..i unscrewed the face plate w/ the still attached d/plate & climbed out to garage to check fit ...went on smooth w/ no shake till near the register ....i backed off two turns & it went smooth for a few turns, did the same a couple more times & the fit was way better than it needed to be for a dog plate ..good enuf for a 3 jaw....( to my surprise, i expected to have to take a couple of cleanup cuts of a thou or so)..... & by backing off a couple turns & then screwing on some more, i was most likely working out some rough cutting. hope this may be of value to some. best wishes doc ------- Re: increasing thrd depth on a dog plate Posted by: "L. Garlinghouse" lhghousex~xxsuddenlink.net Date: Mon Apr 1, 2013 11:08 am ((PDT)) Just a quick comment on this general thread about threads . . . I was making something to screw on the spindle. Knowing I was going to have the problems already discussed, my first step was to make a plug- gage so I could test the threads without doing all the things we have been discussing. For the "master" I used the dog-plate aka face plate as the female thread gage. I managed to get a really nice fit. So I cut the threads on my project and stopped when I had a nice tight fit on my plug gage and was gloating about all sorts of things. Then I tried what I had just finished on the spindle and it was very sloppy. So what went wrong? On my plug gage I had left the crests of the threads too sharp. They had interfered with the flatter root of the thread on the face-plate giving me a false "snug fit." If you have ever seen a real plug type thread gage you will note that the crests of the threads are flat. The thing you are really gaging is the pitch diameter. So when making your thread gage, don't worry about making the crests of the thread flat -- just as long as you don't get down to the pitch diameter. The OD of your plug gage is not important as long as it is small enough. Too big, like maybe according to the max on the spec, and you may get a false positve. L8r, L.H. in Arkansas ------- Re: increasing thrd depth on a dog plate Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Mon Apr 1, 2013 12:09 pm ((PDT)) over many years i have fitted over a dozen back, dog & face plates w/out a spindle dummy ...slow & repetitive trials ....why ? ..mostly afraid of what happened to you .....finally on the barnes 4 1/2 i made a spindle copy, & things went well ...this last thrd deepening, i got lazy & wanted to see what i could do w/ a spring caliper ..i filed the points to 60deg plus a tad to make sure they did not bottom out ...& i wud read somewhere near the middle of the thread. I still am queasy abt using a spindle copy for a 3 jaw, since i want a no shake fit & a register as close to 1/2 thou over as i can get. maybe if i use wires & mic over them, i can make an ACCURATE copy?? i once saw a post in which 3 sizes were cut on the same bar .. no go, go, & way too much. tnx for your experience doc [In a later message this same day Doc wrote: i have mentioned this before, however to me it looks like atlas & other older spindles were cut w/ a V thread & therefore current taps like my 1-1/2 x 8 are useless for fitting to the spindles, since they are made to a different standard.] ------- Re: 1"-10 TPI Nut ??? [atlas618lathe] Posted by: wa5cabx~xxcs.com Date: Sun May 19, 2013 11:40 am ((PDT)) "none" wrote: > >What I'd like to find are a few 1x10 TPI hexnuts to use to > >fabricate tooling for the Atlas 618 headstock. I did just this > >for my old 10" Atlas years ago which can use a 1.5" 8 series > >nut by the way. In a message dated 05/18/2013, dolphin_79605x~xxyahoo.com writes: > Gary, I am unfamiliar with the BSF/BSW system, but 1" BSF is supposed > to be 1" 10tpi and if so, the below outfit has them. Mick > http://www.boltmasters.com.au/nuts/hex-full-nut/bsf/1-bsf-bright-h > ex-nut/afa.asp?idWebPage=47894&CATID=443&ID=21981&SID=443049909 I would point out that the Whitworth Thread Form is a 55 deg. thread with a radius on both the crest and trough. The Unified Thread Form is a 60 deg. thread with flats on the crest and trough. Looking at the thread form drawings in Machinery's Handbook, it is not intuitively obvious that with tolerances and allowances, all properly made nuts of one Form will screw onto all properly made screws of the other in the few cases where nominal diameter and pitch or TPI are the same. However, my experience from my Land Rover collecting days is that they usually will intermate. Bass Tool (local machine tool supply house) offers a large assortment of special thread taps and dies, including 1"-10 Taper, Plug and Bottom x~xx $33.62 ea. If 1" BSF hex nuts would be a useful raw material for you, I would suggest buying some and buying one 1"-10T (Taper) tap (in your use, the Taper will last longer than a Plug or Bottom tap). When you receive the nuts, run the tap through each one. Then put the tap away for future use, and go on about your business. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Date: Wed, 22 May 2013 19:46:55 -0700 From: James Thompson Subject: [OldTools] 12-20 screw threads I found myself in need of some threaded rod with 12-20 threads. I looked in several stores, but the only rod that diameter I could find was 3 feet of 0-1 steel. So I bought it for $5. I own a solid die with the thread, and I was trying to use it, but it was a struggle. The solid die cuts the full depth of thread in the second turn, so it is hard going. 0-1 doesn't like to thread easily. Then I remembered what Scott G. said about finding a split die in 1/4-20 thread and choking it down. The one I have will not choke down to the desired size, so I ran it first, then followed with the correct solid die. It is much easier to do it this way, even though I had to do it twice. I also learned that it will be easier to run a mess of thread on the rod, then cut off the lengths I need rather than trying to thread a little, cut it off, and thread the other end. I have a picture of the two diestocks on a rod. https://plus.google.com/photos/102358420595488787966/albums/58809956408 80636977?authkey=CI7Fr9Sx9JOkGA James Thompson, the Old Millrat in Riverside CA ------- Date: Thu, 23 May 2013 08:08:43 -0400 From: Tom Dugan Subject: RE: [OldTools] 12-20 screw threads Weird. http://www.engineershandbook.com/Tables/threadlimits.htm jumps from #10 to 1/4". I know there are #12 and #14. What gives? Surely #12 is NOT a 1/4" major diameter. ------- Date: Thu, 23 May 2013 09:29:25 -0400 From: Ken Shepard Subject: Re: [OldTools] 12-20 screw threads The #12 has a 0.216" diameter. It was once a common size but fell out of favor by the early 1900's. This was the size used by Bailey and when Stanley acquired Bailey, they continued to use this thread size. There are several theories as to why Stanley used this "non-standard" thread long after it became obsolete instead of one of the more common sizes. These theories (and much more) are discussed in great detail in "Stanley Planes and Screw Threads" by John Bates -- a special publication of the Traditional Tools Group of Australia. Ken Shepard [later message by Clynt in Sydney, Australia] The books by John Bates of The Traditional Tools Group on "Stanley Planes and Screw Threads" may be found as a link on the home page of www.tttg.org.au ------- Date: Thu, 23 May 2013 10:02:07 -0400 From: gary caron Subject: Re: [OldTools] 12-20 screw threads Need to go back a few revisions, to the days when 12 and 14 were more common. I still have taps and dies for those threads, and they can still be got on the bay, if you are so inclined. Gary Caron York, PA ------- Date: Thu, 23 May 2013 07:31:20 -0700 From: James Thompson Subject: Re: [OldTools] 12-20 screw threads I just looked on the bay for a 12-20 tap. I found a total of one, which is declared to be a super rare 12-20 bottoming tap and is priced at only $46. I did find a site online offering a very wide variety of taps including 12-20 which were priced at $10.25. If you have need for a bottom tap you only need to grind off the tapered end, and Viola! (As Kelly Bundy used to say.) You have a bottom tap. I guess I should buy some and grind them so I could offer them on the bay for the bargain price of only $45 each. Yep! Uh huh! ------- Date: Thu, 23 May 2013 07:38:02 -0700 From: James Thompson Subject: Re: [OldTools] 12-20 screw threads Replying to my own post, I thought someone might like to buy such a tap, so here is the url. http://www.victornet.com/cgi-bin/victor/productlist.html?subdepart ments=Special+Thread+Taps:618%2C1170%2C1171 I mis-remembered the price, it is $10.50, which I think this is a very good price. [In a later message] Doing it again. I decided to search for a 12-20 die, thinking that if they make the tap, they might just make the die too. No such luck. They make #12 dies in threads from 26 through 64, but not a 20. Oh, well! It was worth a try. ------- Date: Thu, 23 May 2013 14:53:33 +0000 From: "Maddex, Peter" Subject: RE: [OldTools] 12-20 screw threads Hi, James. St James Bay did a special order tap and die set a while ago. I had to wait until they had enough orders; I got one and it came with a taper tap that is now a bit shorter ;-) Pete ------- Date: Thu, 23 May 2013 16:01:17 +0100 From: paul womack Subject: Re: [OldTools] 12-20 screw threads Is is time for my link again? ://www.geocities.com/ply bench/tour.html#stanley_threads BugBear ------- Acme tap? [Metal_Shapers] Posted by: "Miket_NYC" mctaglierix~xxgmail.com Date: Sat Jul 27, 2013 6:17 am ((PDT)) I just discovered my recently purchased South Bend shaper is missing the nut for the leadscrew that moves the table from side to side. This is a left-hand Acme thread, 1/2" x 10 tpi. Is there any chance someone has a tap this size they'd be willing to lend me or an Acme nut this size to sell me? (I've already noticed what these taps cost, and I'd be willing to give you a security deposit for it if you want.) Of course, if somebody happens to have the missing part for my shaper, I'd be interested in that too, but I'm not exactly holding my breath.... Mike Taglieri ------- Re: Acme tap? Posted by: "FLYWHEELERS CAR CLUB" flywheelersccx~xxgmail.com Date: Sat Jul 27, 2013 7:29 am ((PDT)) Hi Mike. Hey take a look here. http://www.mcmaster.com/#acme-nuts/=nsy9yl I hope this helps. Joe ------- Re: Acme tap? Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Sat Jul 27, 2013 9:49 am ((PDT)) mike ...i have successfully single pointed severa; 1/2 X 10 acme nuts ... the advantage is COST, & the ability to fit to the screw you have available, which will result in a better fit w/ less lash because of the screw wear ...in truth, the BEST answer is to take a cleanup cut on the screw eliminating the wear at specefic spots, & THEN single point the nut to FIT. it is as easy as cutting an internal V thread, only different grind point & parameters ....you can grind the tool out of a lathe bit or use a boring bar /bit setup .....read up on it !.....for the ultimate in minimum back lash, you may try the method used by the Brits : using a 10-20% narrower bit to cut to FULL depth using straight in cutting (compound set in line w/ spindle); after cutting to spec depth, you then take shave cuts on the sides by advancing /retreating compound a thou or so, feeding in w/ the x slide checking for fit until you have what is desired ....straight in feeding works quite well w/ the small thread & lite cuts ......FWIW .. if nothing else, you can use the old screw as a gauge to grind your toolbit, providing clearance of course...at one time i single pointed a 7/16 X 10 SQUARE nut w/ this method....way down on the learning curve, i cut it twice ...stupidly cutting a rt hand thrd the first time .... certainly not a professional machinist ...just an aged home shop guy not afraid to make scrap the first time! best wishes doc P.S. if you decide to go this way, i will walk you thru as best i can, if desired... ------- Re: Acme tap? Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sun Jul 28, 2013 6:48 am ((PDT)) One of the first Acme screws I cut, many years ago, was for the local Cheese factory. It was 304 SS 1" diameter-5TPI. I just could never get the nut to fit! Finally realized the one I'd cut was 4 TPI. (Or visa versa, I don't recall.) And truth be told, that's far from being the only such blunder I've made. Glen ------- Solution to my Acme nut problem Posted by: "Michael Taglieri" mctaglierix~xxgmail.com Date: Sat Aug 3, 2013 12:51 pm ((PDT)) I've been wondering about the various ways to solve my problem of the missing Acme nut on my shaper table. Then I realized this is for the CROSS-travel on the table, not travel up and down, so it doesn't have to be very strong. Also, the travel will always be when the ram is not cutting, so the only thing it has to resist is the friction in the dovetails. So the brass Acme nut from MacMaster-Carr (about $5) should certainly be good enough. If not, it'll get the shaper operational while I make something better. Mike Taglieri ------- Re: Solution to my Acme nut problem Posted by: "x23y4u2" mickeyx~xxthesweetoasis.com Date: Thu Aug 15, 2013 2:36 am ((PDT)) > I've been wondering about the various ways to solve my problem of the > missing Acme nut on my shaper table. This: http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-lead screw-nuts-the-easy-way May be the best solution. You may want to read all 18 pages to see how well this worked out for a number of people. ------- cutting inside thread [atlas_craftsman] Posted by: "ddean49" ddean49x~xxyahoo.com Date: Mon Aug 5, 2013 4:37 pm ((PDT)) I need pointers on cutting an inside thread. I am trying to make a face plate from an old Subaru hub. I have the hub chucked in a three jaw, faced off for the register, bored to 1.420". I have only a lantern tool post and a few hss bits. Any suggestions for a cutting bit? Don ------- Re: cutting inside thread Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Mon Aug 5, 2013 4:51 pm ((PDT)) If you have a tool holder that turns to the left and you can get it in the bore without rubbing your work piece you can use it. A 3/4 -1" boring bar would be ideal. You have boring bars and a boring bar holder? GP ------- Re: cutting inside thread Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Mon Aug 5, 2013 4:51 pm ((PDT)) Don, Do you have a boring bar? Do you have a "fish" to set the correct angle of the HSS cutter? For starters, I would chuck up some scrap aluminum and perfect your skill first. Rick ------- Re: cutting inside thread Posted by: "Donald Lewis" ddean49x~xxyahoo.com Date: Mon Aug 5, 2013 5:18 pm ((PDT)) Nope just hss bits, some junk drill bits, a few broken taps. I think I understand the geometry for outside threads. I am not sure how to translate that to the inside. Don ------- Re: cutting inside thread Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Mon Aug 5, 2013 5:23 pm ((PDT)) Don. Do you have all the tool bit holders that come with the lathe? If yes, tell me what you have. GP ------- Re: cutting inside thread Posted by: "Donald Lewis" ddean49x~xxyahoo.com Date: Mon Aug 5, 2013 6:01 pm ((PDT)) I have one tool bit holder; it is marked 3-139-L. I bought the lathe at a garage sale. It is a 12-36 and came with the lantern post, a 5" three jaw and a lantern tool post. I have very little idea how to use a lathe. But for 150.00$ it will give me a lot of entertainment in my old age. I have no idea what came with the lathe new. Don ------- Re: cutting inside thread Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Mon Aug 5, 2013 6:19 pm ((PDT)) Don. Now first a reprimand, what's the old stuff we don't have any old guys on the forum -- just guys the caught their second wind. Now if you started to turn your blank i would remove it from the chuck and wait till i have the proper tooling. When you go back to finish what you started use the 4 jaw and indicate it back so it runs true. Here is a guy that sells real reasonable and has all types of tools i have bean buying from him. His name is David his e-mail is: tooldocx~xxcheqnet.net I am not affiliated with David but he is a great guy to buy from and you save money. So now spend your bucks and get what you need so you can use your toy, besides you got a steal on the lathe. GP ------- Re: cutting inside thread Posted by: "Donald Lewis" ddean49x~xxyahoo.com Date: Mon Aug 5, 2013 6:36 pm ((PDT)) Thanks GP. I have told many people that a lathe without tooling makes a fair boat anchor. But we all have to start somewhere. It's difficult to decide what you need before you decide what you are going to do. I didn't say I was old but I have every intention of getting that way. It beats the alternative. Does David have a website, catalog, list? Don ------- Re: cutting inside thread Posted by: "David Beierl" dbeierlx~xxattglobal.net Date: Mon Aug 5, 2013 6:40 pm ((PDT)) Have a look at https://picasaweb.google.com/117189706757545167023/Threading?auth user=0&authkey=Gv1sRgCJmEy7Hgrsfjdw&feat=directlink Yours, David Beierl ------- Re: cutting inside thread Posted by: "Donald Lewis" ddean49x~xxyahoo.com Date: Mon Aug 5, 2013 7:05 pm ((PDT)) Thanks David, that will keep me busy for the rest of tonight. Don ------- Re: cutting inside thread Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Tue Aug 6, 2013 3:42 am ((PDT)) Don Just e-mail David and give him a idea of what you need. He will get back to you. As far as i know he does not have a website. David send me a catalog He is a retired man that was a buyer i believe for a big company. He said to me that he can offer tooling cheaper as e-bay does. I bought magnetic Dro's for my mill from him and some other mmeasuring devices and some tooling. GP ------- Re: cutting inside thread Posted by: jerdalx~xxsbcglobal.net jtiers Date: Mon Aug 5, 2013 8:52 pm ((PDT)) You can grind an inside threading tool from a regular cutter blank, although it is a fair bit of grinding, and it is limited in the depth it will handle. But you may have a blank around now, as opposed to ordering stuff. I have a couple of them. A standard boring bar that takes short pieces of HSS cutter stock will do fine, you grind the short piece to a 60 deg angle with relief for the thread cutting. JT ------- Re: cutting inside thread Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Tue Aug 6, 2013 4:27 am ((PDT)) Jt. This member needs tooling, let him buy some. Cutter blank is round. Most boring bars use square tool bits. I have made boring bars and used cutter blank (round). GP ------- Re: cutting inside thread Posted by: "John Cibulskis" jacs1954x~xxnetzero.com Date: Tue Aug 6, 2013 6:05 am ((PDT)) Don: YouTube, has a lot of very good videos, from beginner's, to professional. you can get a lot of useful visual demonstrations, that for sure will help you get going. John c ------- Re: cutting inside thread Posted by: "Don Wilson" wilstyxx~xxtampabay.rr.com Date: Tue Aug 6, 2013 7:22 am ((PDT)) Check this out. I made one and it worked perfectly. http://madmodder.net/index.php?topic=3523.0 ------- Re: cutting inside thread Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Tue Aug 6, 2013 7:33 am ((PDT)) Don, Elegant solution! Thanks, Rick ------- Re: cutting inside thread Posted by: jerdalx~xxsbcglobal.net jtiers Date: Tue Aug 6, 2013 7:15 pm ((PDT)) The threading tool tool ends up similar to a commercial Criterion or Bokum boring bar. If you keep the "stem" as large as possible, it is stiffer, naturally. Aside from being non-HSS, it should work fine, and you get lots of re-sharpenings from it. JT ------- Re: cutting inside thread Posted by: jerdalx~xxsbcglobal.net jtiers Date: Tue Aug 6, 2013 7:10 pm ((PDT)) Round? Not in my world..... lathe cutter blanks are square.... 3/16", 1/4", 5/16", etc, etc.... And the boring bars *we* would typically be using take the smaller sizes. (I do have some bars up to 1.5" diameter, but they don't get used at home.) Larger sized blanks can be ground to be good inside threading tools. If you want, I can show pictures. (I DO also have some boring bar carbide cutters that are round with flats for the screw, but oddly, no bars with round holes.) As for the OP buying tools, sure, why not? I find it faster to buy what I need to do the work rather than making tools in many cases. In other cases, I DO make the tools and then do the work. However, I see too many folks who wait for money to buy what they could make now, never considering that it may be makeable fairly quickly and easily, often at substantially lower cost than buying. It happens that boring bars of the inserted cutter type are a pain to make, unless you DO use round cutter inserts, because the square holes for typical lathe cutter stock are a nuisance to do. But grinding a threading tool from a cutter blank is not so difficult, and can generally be all done and being used days before any order would arrive. Just as the OP [Original Poster] prefers. Make, order, whatever. JT ------- Re: cutting inside thread [atlas_craftsman] Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Aug 6, 2013 1:58 pm ((PDT)) On August 06, 2013 Don Wilson wrote: > Check this out I made one [thread cutting tool] and it worked perfect http://madmodder.net/index.php?topic=3523.0 don ...nice idea.....have not seen the double cuttng edge before ....shud be great for OD & large ID, .......for small ID, i use a 1.4 in boring bar or one of several grond lathe bits i keep handy. FWIW i have a few comments, most of them learned the hard way utilizing a large scrap pile over the last 60 yrs .....by having the cutting edge below center, there is built in clearance, as you knew although the machinist you talked to apparantly did not. i wud recommend heating the tool in a drill press circa 200 rpm ...heat is even this way & when you quench, just raise up the can of whatever you are quenching with: ATF, sae 10 or whatever light oil if using w-1 drill rod.. ..this way the quench is even & warpage is minimal, (neck is where it is more likely & more devastating ...i keep a "bananna" reamer around to remind me .... particularly inportant for quenching reamers, but valuable for all )...of course if you desire to harden the shank as well, not sure why, but this obviously cannot be done. easier to see the color desired in a dull light ....everyone's eyes are different but cooked carrots is abt right for me .......also if you have a 3rd hand, the steel becomes non magnetic at the critical quenching temp. if using 0-1 which i prefer, i wud draw the temper at abt 375 in the kitchen oven for i hour, or if w-1, i wud do the same only at abt circa 415 ....drawing to a blue is way too soft (spring steel)...look for a straw color & quench in brine ..less chance of cracking at the neck.... possibly if your tool had been drawn, it may not have droken off, properly drawn, a file will still not bite, .....& it will be way less subject to breakage. best wishes doc -------- Re: cutting inside thread Posted by: wa5cabx~xxcs.com wa5cab Date: Tue Aug 6, 2013 9:58 pm ((PDT)) In a message dated 8/6/2013, jerdalx~xxsbcglobal.net writes: > (I DO also have some boring bar carbide cutters that are round with > flatsfor the screw, but oddly, no bars with round holes) Probably for milling machine boring heads. Or for the QCTP boring tool holders. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: cutting inside thread Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Wed Aug 7, 2013 3:39 am ((PDT)) JT: In the professional machine world if one refers to cutter blank, one refers to round. Square cutter blank as you call it is referred to as a tool bit. GP ------- Re: cutting inside thread Posted by: jerdalx~xxsbcglobal.net jtiers Date: Wed Aug 7, 2013 5:47 am ((PDT)) I like your pointed use of the word "professional".......as opposed to "amateur bunglers"......which probably means the rest of us who are not you..... But you may find that word usage actually varies among "professionals" depending on where you are. Yes, "cutter" is, at least among folks who live "up east", usually a "milling cutter"..... 'taint always so elsewhere. A "professional" (or an amateur bungler) would call the unground piece a "blank", and the term "tool bit" would be a "blank" that has been ground into some presumably useful shape which has a cutting edge. Although I have seen an unground (but reasonably sharp) new blank used for roughing on a very large lathe. JT ------- Re: cutting inside thread Posted by: "Donald Lewis" ddean49x~xxyahoo.com Date: Wed Aug 7, 2013 8:37 am ((PDT)) OK Update. I have attempted to attach pics of my lantern tool post and my newly made boring bar. Now I need to grind a threading bit and with the information from David I may be on my way. Thank you all. Don ------- Re: cutting inside thread [3 Attachments] Posted by: "Carl Hollopeter" chollox~xxbellsouth.net Date: Wed Aug 7, 2013 10:14 am ((PDT)) Don, That should work, however IMO you have way too much of the bit sticking out of the boring bar. Can’t tell from your photos but hopefully you can loosen your clamp bolt and slide it back till “just enough” sticks out to cut your threads. You will want to keep everything as short and stout as possible to increase rigidity. Also take very small cuts. Good Luck! (Practice on some scrap first) Carl H ------- Re: cutting inside thread Posted by: jerdalx~xxsbcglobal.net jtiers Date: Wed Aug 7, 2013 9:41 pm ((PDT)) If the attachment comes through, here is a picture of some boring/ threading bars usable for inside threading. The left one next to the rule is a regular boring bar of the type taking a short piece of lathe tool /cutter in a square hole. (It has a grooving tool in it at present, not a 60 degree threading tool.) The other two were ground out of solid blanks. The boring bar has about the sort of tool stickout that you want.... as little as possible, just enough to allow cutting the feature you need, which is in your case threads. You appear to have an extreme amount of 'stickout", which usually has a very bad effect. If you stick out the cutting tool too far, you get several problems... First, there is a lot of torque on the bar, which wants to twist it in the holder. Second, you are open to chatter, caused by the springiness of the tool and bar. The shorter the distance from the support to the cutting edge, the less the springiness, and generally the less the chatter. For "completeness", I have to mention that properly controlled, springiness can actually reduce chatter, but that is with a specifically designed tool, one that reduces its depth of cut as it springs. Normally, a cutting tool tends to dig in as it springs, which increases chatter. JT ------- Re: cutting inside thread Posted by: "cliff" kenx~xxucsp.com Date: Thu Aug 8, 2013 6:33 am ((PDT)) Good points and example pix, JT. Here's something I do that has worked out well over the years; I have many old Allen wrenches (I sometimes buy a bunch at yard sales or flea mrkts), anyway just pick the biggest size for the bore and grind off the shorter leg so it just can be ground to the cutter shape you need. Cheap, easy, fast, and the spring in the Allen wrench seems to be of the good kind -- rather like the goose neck tool holders. As time goes by one builds up almost any needed shape or size 'bar' this way. Anyway this works well for me, maybe it will work for someone else also. ------- Re: cutting inside thread Posted by: "Donald Lewis" ddean49x~xxyahoo.com Date: Thu Aug 8, 2013 5:38 pm ((PDT)) The attachment shows the final configuration of the thread cutting rig I used. Then thread is cut. The face plate screws onto the spindle fine. Due to lack of forethought, after doing the truing cuts on the face plate the spindle nose sticks through. Not a terminal problem but not what I had in mind. I have considered putting a shim behind it but that will effect repeatability. I may build up the register surface with weld and re cut to true. Or I could just cut another; I can use the practice anyway. I like the Allen wrench idea, I have a pile of those. I now have the experience of making a boring bar, grinding a threading bit, cutting a thread with a lathe and making lots of chips. Total money spent 0. That = a good week and it is only Thursday. Thanks for all the help. Don ------- Cutting threads [atlas_craftsman] Posted by: thehairsx~xxoptilink.us Date: Sat Sep 7, 2013 3:16 am ((PDT)) When cutting 1/2 - 20 threads on drill rod using may Craftsman 12 inch lathe I'm getting threaqds that fit the nuts, but the threads themselves are rough. Am I cutting too deep on each pass? If not what is the secret to cutting smooth threads. How many thousands should I be cutting on each pass? D.Hair ------- Re: Cutting threads Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Sat Sep 7, 2013 3:39 am ((PDT)) David, I hope you are not using a carbide threading tool bit. GP ------- Re: Cutting threads Posted by: "David Hair" thehairsx~xxoptilink.us Date: Sat Sep 7, 2013 6:56 am ((PDT)) I've tried both HSS and carbide and they both do the same. I will admit that carbide does the worst. D.Hair ------- Re: Cutting threads Posted by: "Charles Gallo" Charliex~xxTheGallos.com Date: Sat Sep 7, 2013 4:40 am ((PDT)) 1) not using drill rod if you don't need to harden it. 12l14, 1144 heck, 316 stainless is easier than most drill rod 2) properly ground and sharp cutters, and or inserts 3) good cutting fluid. For drill rod, threads that large, a dark sulphur cutting oil 4) speeds and feeds. Yes folks, I know it is scary to run threads fast, but as you get more experience you'll tend to run faster, and get better finishes. ------- Re: Cutting threads Posted by: jasjms2x~xxyahoo.com Date: Sat Sep 7, 2013 4:52 am ((PDT)) First of all if your single pointing the threads using the machine, you must use a thread V Gauge, we old timers call it a Fishtail, to square up your tool bit in relationship with the piece you are threading, this Fishtail also is notched out so you can grind your tool bit to the proper angle for threading. Makesure you have the proper rake and clearance on the tool bit, otherwise you will not get a good finish on the work piece. Also take moderate cuts so the piece doesn't spring or use a center hole on the end of the piece to ensure rigidity. Use either white lead or a good sulfur base oil when cutting the threads. Your finish cut should be light at the end of the thread cutting, and no cut at the end do the finish will be better also. I use a small V shaped file to smooth out the threads. I have had my original Craftsman lathe since 1967, and I still tinker around with it. Good luck on your threading. Jim ------- Re: Cutting threads Posted by: jerdalx~xxsbcglobal.net jtiers Date: Sat Sep 7, 2013 6:30 am ((PDT)) Material of cutter is not overly important. Geometry of cutter is. Material being cut is. You can cut good threads having a good finish with a carbide insert and not have to run fast. I have done it in certain types of steel. Those steels worked well with HSS also. Some materials, including some drill rod, do not cut smoothly at low speeds. To get a decent finish on those, you must run faster, and to do that, you may need carbide. Another reason for problems is that the geometery of most threading tools, including carbide, is stupid and wrong. They have a flat top face, and so they "plow off" the material instead of cutting it the way a sharp edge and lots of rake does with a regular turning tool. While you CAN make a raked threading tool, it requires a lot of work, and/or compensation for odd angles, so it isn't done. The result is that threading tools "plow" the metal and leave those burrs on each side of the "furrow". That problem is reduced at high speeds, accounting for another reason to use faster speeds, especially with carbide. With some materials, built-up "piles" of the cut material stick to the cutting tool (partly due to the flat top face) and will drop bits of that material which becomes welded-onto the cut metal and leaves roughness as well. Lots of oil helps in that case. A valid complaint about carbide tooling is that it is "dull".... it cannot generally be sharpened to a keen edge, and if you DID so sharpen it, the edge would be broken down very quickly. Carbide is particles of hard stuff in a "cement" made of a softer metal. It's a bit like "sharpening concrete". A duller tool works better at higher speeds, which partly accounts for the idea that carbide cannot be used except at extreme surface speed (and with a high power machine). There are reasons for the existence of "free machining steels" and this is one of them. Free machining steel cuts clean, and has no tendency to "re-weld" particles back on the cut surface. That is due to the sulfur or lead additives in the steel, which, among other things, "poison" the surface and mess up welding. You really can't weld these materials in any way, intentionally with an arc welder or unintentionally on a machine tool. Free machining steel is not very strong, however. But cut threads are not the best anyhow, and most threads are "cold-rolled" now. Rolled threads are a degenerate form of forging; the "grain" of the metal is formed, not cut across, and the part is much stronger. Work-hardening due to cold- forming also strengthens the part. JT ------- Re: Cutting threads Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Sat Sep 7, 2013 7:16 am ((PDT)) On 9/7/2013, David Hair wrote: > I've tried both HSS and carbide and they both do the same. I will > admit that carbide does the worst. For me it depends on the carbide. Most of mine do a real smooth finish and have a razor sharp edge. The new ones with real fine grain, new alloys and fancy coatings cut real smooth. Some of mine are coated with titanium or nickel alloys. The old set that came with the lathe do well but even rotating to new tips are not as sharp as the new tech ones and have the metal buildup on the tip. They are the type the old-timers say are not as good and are used to. Some will match the finish of the HSS shear cutter I have; real nice as I can get the same finish on a heavier cut but still can do a 0.0005" cut. Still will chip in a heartbeat on interrupted cuts if it has a chip breaker. That is all I use HSS for. If you want awful finish, pick up some Chinese brazed carbide cutters off ebay. ;) Scott G. Henion Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 Welding pages and homemade welder: http://shdesigns.org/Welding ------- Re: Cutting threads Posted by: "James Irwin" jirwin1x~xxaustin.rr.com Date: Sat Sep 7, 2013 7:21 am ((PDT)) Drill rod is difficult to machine smoothly. Final passes need to be very shallow...only a thouą or two. Use plenty of good cutting fluid. Of course, the rod being threaded must be held quite firmly and the tool must be quite sharp and smooth and itself held firmly. So why not thread using an adjustable die? Spread it open a tad for roughing, then close down to final for the fine pass. Jim ------- Re: Cutting threads Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Sat Sep 7, 2013 9:34 am ((PDT)) Maybe this will help http://rick.sparber.org/spt.pdf Rick ------- Re: Cutting threads Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Sat Sep 7, 2013 11:33 am ((PDT)) On 9/7/2013, David Hair wrote: > OK. I haven't just asked and left. I have honed both the HSS and > carbide tools and cut more threads. I think my major problem was just > cutting too fast. If 'm right turning my dial in 5 thousands is > actually doing a 10 thousands cut. Can someone tell me for sure if the > late model Craftsman 12" is a direct reading or total reading dial. > All cuts when I feed only .003 per pass and do 2 or 3 cleaning passes > at the end are looking much better. The dials are direct reading (will cut diameter by 2x amount dialed in). You should be using the compound at 29.4 degrees of perpendicular. Moving the dial will advance the cutter 87% of the dial due to the angle. The Atlas Manual of Lathe Operations and Machinists Tables has the amounts to advance the compound. You can probably find them online. I use a cheap small C clamp (1") on the cross slide as follows. 1. Put the compound in the center of travel. 2. Advance cross slide up to the work. 3. Place C clamp in front of cross slide as a stop. 4. Back off compound a bit and advance cross slide up to clamp. 5. Advance compound until cutter just touches. From there advance the compound the desired cut. Then back off the cross slide a turn or so. Move back to start of thread and turn cross slide back up to clamp. Then advance the compound for the next cut. This avoids the step of backing off the compound then having to remember where it was on the next pass. The alternative is to zero the cross slide and back off then return to 0 between passes. I said _cheap_ C clamp. It is real soft steel and does not harm the slide way. I sometime put a piece of aluminum under it but it works without it and does not need to be very tight. Somewhere I have a plastic woodworking clamp I have used. If you are using the cross slide to advance, then you will get rough threads. Scott G. Henion Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 Welding pages and homemade welder: http://shdesigns.org/Welding ------- Re: Cutting threads Posted by: "Carl Hollopeter" chollox~xxbellsouth.net Date: Sat Sep 7, 2013 3:45 pm ((PDT)) Scott, Don’t have your machine but you can verify direct or total dial reading by simply setting up an indicator and cranking into it. Just remember you will be cutting twice what the indicator shows but you can verify what your dial is reading. Probably should be the first thing to do when starting to run a new “different” machine. You could also chuck up a piece of scrap, mike it, take a known cut, say .010, then measure it again. Should then leave no doubts about your dial reading. Carl H ------- Re: Cutting threads Posted by: "James Irwin" jirwin1x~xxaustin.rr.com Date: Sat Sep 7, 2013 7:17 pm ((PDT)) Atlas and most lathes dials read in depth of cut, so if you dial in 2 thousandths on the crossfeed dial, you take 4 thou off the diameter. Taking 5 thou in a threading pass is OK to conservative for roughing. 1 to 2 thou to get close, and 1 thou to finish....IF one wants best possible finish, has sharp tools and everything tight (Including the headstock bearings). Iąm wondering how you honed the carbide tools??? The green wheel or a diamond is about all that will phase a carbide tool. Ask me how I know!!! Normal abrasive wheels just donąt do a thing good. Jim Irwin ------- Re: Cutting threads Posted by: jerdalx~xxsbcglobal.net jtiers Date: Sat Sep 7, 2013 9:16 pm ((PDT)) > Cutting threads Honing carbide usually doesn't do much good.... > it doesn't stay sharp the way HSS can. I guess I'd figure about 3 thou is about the minimum for carbide in terms of depth of cut, and probably larger than that on average. I HAVE seen inserts that would dust off a thou, but not for long. Green wheels don't give sharp edges, diamond will. JT ------- Re: Cutting threads Posted by: jerdalx~xxsbcglobal.net jtiers Date: Sun Sep 8, 2013 5:52 pm ((PDT)) September 8, 2013 "jerdalx~xxsbcglobal.net" wrote: >> That does end up with negative rake, and a possible geometry change, >> on the trailing "cleanup" angle, which may not be such a great idea. >> Ideally you would cut a groove down the middle, similar to a cutoff >> tool, leaving a small flat on each edge. That would preserve >> everything, but is harder to do. JT September 08, 2013, Charles wrote: > If you put the compound cross slide at the proper angle and feed with > it, only the tool edge with the proper rake will be cutting anything. > The V you are talking about would assume you are plunging directly in, > which is not optimal in my opinion for these small lathes. Reading the > old books, it is evident that there was once a lot of controversy about > feeding in at an angle, but I think it has been resolved and is "modern" > practice for non CNC. If you do it right, you DO "dust off" a bit because you set to just under the flank angle....29 1/2 deg or so , NOT 30 deg. That way most cutting is on the "front", but the back gets a "cleanup" cut as well. If you leave a bit of the tip flat, for many threads, that is about the whole depth, and you don't get the benefit of rake. It IS possible to correctly set the angles to give a good threadform despite rake, but it is more fancy grinding than the average HSM is interested in doing. And you still get negative rake on the back. If you increase speed drastically, you can avoid so much "plowing", it will cut cleaner, but there are other disadvantages for non-CNC operation at such speeds...... like your reaction time. JT ------- Re: Cutting threads Posted by: "Curt Wuollet" wideopen1x~xxcharter.net Date: Sun Sep 8, 2013 7:12 pm ((PDT)) On 09/07/2013 05:20 PM, Doc wrote: > grinding in rake on a single bit of HS is really pretty simple > ......just place the bit at an angle that grinds the rake away > from the cutting edge (the left leading flank of a rt hand > thrd). as you grind, you gradually approach the cutting edge > & STOP before you grind into it, thus maintaining the correct 60 > deg.....you can stone the final few thou if you wish at a > slightly less angle than the rake angle you ground in. > .......this makes a noticeable difference in a clean cut, > allowing deeper depth of cuts ....a gooseneck spring tool allowing > even deeper depth of cut. > if you are using a disc type HS treading tool, one usually does > not grind in the side rake for the sake of the life of the disc > .....i usually use the disc thrd bit & reserve the rake grind > & gooseneck tool holder for coarse thrds /difficult materials. > best wishes > doc On both the parting and threading issues, I was amazed on the Leblond at work. It was just about as nasty as the 6x18 and the 7x14. We are retooling with carbide insert tools as they are carried by the only local source and I'm spending most of my time on automation and control rather than machining. Anyway, I ordered a "miracle" insert parting tool and a single point threading tool that uses inserts. The parting tool has sort of a spoon shape on top and looks way too fragile as the inserts are only 1/4" high and are clamped top and bottom rather than the usual. The threading inserts are pretty much a single extremely sharp 60 degree tooth. I was skeptical, but the results in my quicky tests were awesome in stress proof steel which is kinda crisp for lack of a better term. I can't see anything special about the threader, but where I was getting all sorts of tearing and ugliness with a sharp hss tool, it cut like butter. It did leave light "swirly" marks in the threads. The parting tool was pretty amazing also. I think its magic is the rake provided by the dish on top and the fact that it is relieved in back of the cutting edge. It cut a nice straight curl and I fed right to center to keep it cutting. When I get a chance, I will study the forms to see if I can make things better on the light lathes. In both cases, they seemed to cut very easily with less tool deflection. Just a data point. I wouldn't have believed it if I hadn't seen it. Regards cww ------- Re: Cutting threads Posted by: "rogers92026" brogers9941x~xxsbcglobal.net Date: Sun Sep 8, 2013 7:55 pm ((PDT)) Doc, thanks for the explanation. A couple of days ago I thought that I had a revelation that it would be easy to put in side rake (doing what you mentioned in your recent post). I thought that I came up with something new. Ha ha. Then I read your post indicating that it is something that others (including yourself) have thought of in the past. I suspect that the grind that you mentioned will help to make a nicer looking thread. I'm going to grind a HSS bit as you mentioned. Many thanks. I always appreciate the many bits of wisdom that you share with us. ------- Re: Cutting threads Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Mon Sep 9, 2013 12:16 am ((PDT)) While you CAN make a raked threading tool, it requires a lot of work. ------- CNC threading on a mill idea [SherlineCNC] Posted by: picmaxx~xxgmail.com Date: Sun Sep 15, 2013 9:41 am ((PDT)) This may not be a new idea but I'd like to gather some feedback anyway. First of all I have both a mill and a lathe but only the mill is CNC'ed. I'd like to be able to cut thread without the Sherline thread cutting attachment. So here is the idea. 1. Turn the piece on the lathe to appropriate dimensions. 2. Mount the piece with the chuck on the mill. 3. Mount a cutter sideways on the X table, pointing in the X-X direction. Align the cutter with the piece. 4. Remove the standard motor and mount the Sherline stepper motor spindle kit on the Mill. 5. Switch the Y-axis stepper control cable to the spindle stepper motor. 6. Write simple g-code to cut the thread. Calculate and use simple linear interpolation in the Y-Z plane to synchronize the workpiece rotation and the feed for desired the thread pitch. 7. Back off in X, retract, advance X, repeat step #6 until the thread is cut to depth. It seems it will work. Any potential issues you guys can see? Thanks Max ------- Re: CNC threading on a mill idea Posted by: "Sonny Mounicou" sonnyx~xxmounicou.com Date: Sun Sep 15, 2013 9:46 am ((PDT)) Max, Get a threadmill bit and you'll have a much easier time. ------- Re: CNC threading on a mill idea Posted by: picmaxx~xxgmail.com Date: Sun Sep 15, 2013 11:07 am ((PDT)) Sonny, Thanks for the suggestion. I will take this into the consideration for my overall threading needs. Thread milling can be an easier solution but it is less flexible and may have problems of clearance and reach. Max ------- Re: CNC threading on a mill idea Posted by: "Sonny Mounicou" sonnyx~xxmounicou.com Date: Sun Sep 15, 2013 11:18 am ((PDT)) Max, No problem. I've used both on different occasions, but I find thread milling much easier. And honestly I try to minimize the times I have to overhaul my setup. Swapping motors between machines and such while possible, makes for a much longer setup/alignment cycle. The MSMStdMill setup makes using a mill like a lathe pretty easy. Even though it's for Mach3, you may want to look over the documentation for it to get some ideas. Lastly, I'm about to start working up a mount for the headstock so that I can mount a stepper without removing the DC motor. Then I could mount a normal tap and use a tool offset to tap many small holes easily. Though you are probably talking about external threads, a die could be mounted in the same fashion. Anyway, good luck on your adventure! Let us know how it turns out. ------- Re: CNC threading on a mill idea Posted by: "jowhowho" jowhowhox~xxyahoo.com Date: Mon Sep 16, 2013 6:49 am ((PDT)) The mill is not as rigid as the lathe, and this will cause some increased deflection and chatter. For some threads you will find this works, for other threads you'll need thread milling, and for some threads, you may have problems that only a CNC lathe, or a threading attachment will handle. Oh, and sometimes taps and dies work great. If you want to add an archaic skill, take up hand thread chasing. You can do this on a lathe with no CNC or threading attachment. ------- Patting myself on the back [myfordlathes] Posted by: "Haydut1200" haydut1200x~xxgmail.com Date: Tue Sep 17, 2013 4:23 am ((PDT)) No big deal for most, if not all of you, but after around 35 years of owning a lathe of some description, today I cut my very first thread on the lathe. Having plenty of taps and dies of all the usual flavours, I never needed to do any screwcutting. Until today, when I wanted a mandrel for my Dremel chuck. The thread is 7.1mm x 40tpi, so probably not the best size for a first attempt, but it came out OK albeit with a rather rough finish. I've got Mr Sparey's book, 'The Amateur's Lathe' to thank for making it easier than I thought it might be. Martin, chuffed to bits. ------- Re: Patting myself on the back Posted by: "David Everett" deverett2003x~xxyahoo.co.uk Date: Tue Sep 17, 2013 5:07 am ((PDT)) It's always satisfying when a new skill has been achieved. I have cut many standard threads with a single point tool, but have always followed the screw cutting with a die to ensure the thread looks almost presentable. Dave The Emerald Isle ------- Re: Patting myself on the back Posted by: "Malcolm Tulloch" malc395x~xxbtinternet.com Date: Tue Sep 17, 2013 7:40 am ((PDT)) Martin, You have every right to be chuffed, well done mate, it's nice when you do something different & it works out OK. ------- Re: Patting myself on the back Posted by: "Robert Mitchell" rmm200x~xxyahoo.com Date: Tue Sep 17, 2013 8:03 am ((PDT)) I hesitate even mentioning this to a long time lathe owner -- but your project of a Dremel mandrel is well served by mild steel. Free machining steel like C12L14 (dare I say leaded steel) takes a thread beautifully, and is well worth the minor cost. ------- Re: Patting myself on the back Posted by: "Yi Yao" yix~xxyao.ca Date: Tue Sep 17, 2013 9:46 am ((PDT)) Very nice. That's an odd looking thread, good thing you had a lathe handy! How many tries did it take you? I remember my first time. I put my compound on the wrong angle and the threads ended up looking like buttress threads. A smart person would learn from their mistakes, but alas, I've made that same mistake multiple times. ------- Centec mill ACME threads to cut [myfordlathes] Posted by: philx~xxhvtesla.com philiptuck Date: Fri Sep 20, 2013 10:23 am ((PDT)) All, I have a few questions regarding an old Centec 2 mill in need of two 8 tpi lead screws and nuts, all of which I'm hoping to make, and with limited thread cutting experience, I feel I need some advice. The two threads in question are a 0.5 inch 8 tpi RH, and a 0.5 inch 8 tpi LH. Starting with the nuts, 0.5 inch 8 tpi taps seem hard to find, so I can either screw cut two 0.5 inch 8 tpi internal nuts, or convert to 10 tpi for which I can easily get a tap and then cut their corresponding lead screws at 10 tpi on the lathe. (The index dials needed replacing anyway.) So firstly is a 0.5 inch 8 tpi internal thread going to be hard to cut on the lathe because of the size? Secondly, I was considering get some ground 0.5 inch bar to use for the lead screws (rather than turn some larger stuff down) and thought of a free cutting silver steel, so any recommendations? I was wondering if stainless, which a YT video suggests, would probably be too much for thread cutting on a Myford possibly? Lastly, most lathe imperial threading tools seem to be from America, Chronos & the RDG mafia only stock the Acme taps, so do most people grind their own using a gauge? Phil ------- Re: Centec mill ACME threads to cut Posted by: "Paul Farmer" paulfarmer609x~xxyahoo.com Date: Fri Sep 20, 2013 11:05 am ((PDT)) Pill, Early models had a feed screw 1/2" x 10tpi later models had 5/8" x 10tpi. Suggest you join this group http://groups.yahoo.com/group/centec_milling_machines/ Paul ------- Re: Centec mill ACME threads to cut Posted by: paulfarmer609x~xxyahoo.com Date: Fri Sep 20, 2013 11:25 am ((PDT)) 1/2 x 10tpi taps and dies, either left or right thread, are Ł15.00 each. ------- Re: Centec mill ACME threads to cut Posted by: "Phil Tuck" philx~xxhvtesla.com Date: Fri Sep 20, 2013 11:35 am ((PDT)) I'll look over at the Centec group, but mine is so heavily modified (previous owners) it's only a Centec by name. Certainly my screws are 8 tpi at present and not the 10 you say it should have. Conversion to 10 tpi seems the easiest route, especially as one lead screw is shot anyway and needs replacing (the other is debatable). Have you or anyone else any thoughts on the best material within a Myford S7's capabilities? Phil ------- Re: Centec mill ACME threads to cut Posted by: "Paul Farmer" paulfarmer609x~xxyahoo.com Date: Fri Sep 20, 2013 11:58 am ((PDT)) 1140 stessproof Atlas superior ground 1040 Some local Bearing stockist can sell you a length of ACME bar. http://www.tizaro.com/product/FA1FDD/lancaster-lc01201003pldar-thre aded-rod-lcs-acme-10-ft ------- Re: Centec mill ACME threads to cut Posted by: "Phil Tuck" philx~xxhvtesla.com Date: Fri Sep 20, 2013 1:29 pm ((PDT)) Handy link, I had never heard of Tizaro before. I can't use acme bar though as the first 8 inches or so are of plain 0.5 inch bar with only the last 8 inches with an acme thread. I rather fancy the challenge of turning it on the lathe now. Just researching the material suggestions. Threading it longer than needed and then cutting a piece off to turn into a tap, would mean any 'glitches' from my screw cutting won't matter so much as well. I suppose silver steel would then have its advantages for making the tap. Phil ------- Re: Centec mill ACME threads to cut Posted by: "Ken Strauss" ken.straussx~xxgmail.com Date: Fri Sep 20, 2013 4:28 pm ((PDT)) You might want to consider making the nuts of Delrin® (Acetal) rather than the traditional bronze. See http://bbs.homeshopmachinist.net/threads/43645-Making-Acetal-lead screw-nuts-the-easy-way I've successfully made several nuts as described in the article: 1. Drill axial hole in Delrin. The hole should be somewhere between the thread root diameter and diameter. For example, I used an X-drill for half-inch threaded stock and the hole was probably too large. 2. Saw Delrin tube along axis. 3. Put two halves in vise with threaded rod in the middle. 4. Heat *ROD* with hot air gun until Delrin softens while tightening the vise. The melted plastic will ooze out the ends and the saw-cut gap will close. 5. Let things cool without disturbing the rod. 6. Use Vise-grips to unscrew threaded rod. 7. Grind end of rod into a D-bit and run through the nut a few times from each end to make for an easier fit. 8. Thread nut onto rod, chuck rod, turn outside and ends of the nut. ------- Re: Centec mill ACME threads to cut Posted by: "Phil Tuck" philx~xxhvtesla.com Date: Sat Sep 21, 2013 5:34 am ((PDT)) Ken, My initial thoughts on this were rather dismissive, and the word 'bodge' flashed across the screen, but on actually reading the link and seeing the results, I am very surprised at the excellent, or so it seems, result. My nuts are easy to get to (no sniggering) so if it didn't work, removing and replacing with brass or bronze is not too difficult, so I will give Delron a try. Paul emailed me a couple of links off list showing the ACME standard threads and my 0.5 inch x~xx 8 tpi is NOT one of them. I assume therefore someone must have had a set of graduated 0-125 thou micrometer dials to hand, and replaced the original (worn?) 10 tpi screws, with the present 8 tpi that I have now. Using some 0-100 thou Myford dials and reverting back to 10 tpi seems the favourite choice. Phil www.hvtesla.com ------- Re: Centec mill ACME threads to cut Posted by: "Kevin" tadpolex~xxbtinternet.com Date: Sat Sep 21, 2013 7:14 am ((PDT)) philx~xxhvtesla.com wrote: > Secondly, I was considering get some ground 0.5 inch bar to use for the > lead screws (rather than turn some larger stuff down) and thought of a > free cutting silver steel, so any recommendations? Phil, I've always found silver steel, and gauge plate, to be very nice to work with. That said, twice in the last year or so I've come across extremely hard inclusions while machining, hard enough to put grooves in the HSS tool. There is a specifically free cutting grade, but you might struggle to find it in the size you want. If you decide not to go with silver steel, which is normally ground to size, then personally I wouldn't be seeking out ground material. You can get "precision ground mild steel", but I would have thought that 0.5 inch as drawn material would be suitable for this job. Regarding the ACME rod mentioned in another post, and your need for a length of 0.5 diam unthreaded, you could always join a suitable piece of plain onto the end of a piece of threaded (reduced plain diam into a suitable hole with Loctite, or reduced diam threaded connection if you really want to). Silver steel normally comes in 13 inch lengths, so if you need 8 plus 8 you'd have to do some joining anyway. Kevin, NW England, UK ------- Re: Centec mill ACME threads to cut Posted by: "Andrew Curl" methuselahx~xxntlworld.com Date: Sat Sep 21, 2013 9:50 am ((PDT)) Chaps, a freecutting grade of silver steel has been mentioned twice in this thread now -- where does this mythical stuff come from? I used to buy it up to the early '90's, when legislation stopped the use of selenium in the alloy, and as far as I know, it hasn't been available since. What am I missing? As to the original question, EN8 is my solution to most things needing some sort of toughness (without un-machineability) and using silver steel and screwcutting an acme thread just sounds like expensive, wanton pain and suffering to me. I've never come across silver steel feedscrews in real life; only on newsgroup speculations. I'd use EN8M, and if that weren't enough, I'd look into cyanide hardening it as well. As to the nuts, brass won't hold up. Red bronze is a pig to work with, but a good compromise is leaded or phossy bronze instead. However, a fellow might want to investigate to possibility of using recirculating ball screws if he needed to replace both feedcrews and nuts. They are not as expensive as they once were, and the attractions of zero backlash are pretty obvious. Andrew UK ------- Re: Centec mill ACME threads to cut Posted by: "Ken Strauss" ken.straussx~xxgmail.com Date: Sat Sep 21, 2013 4:13 pm ((PDT)) A possible issue with converting to ball screws is that cutting force on the table can backdrive the screws. This isn’t a problem in CNC applications because the screws are restrained with steppers or servos. ------- Re: Centec mill ACME threads to cut Posted by: "Phil Tuck" philx~xxhvtesla.com Date: Sun Sep 22, 2013 12:30 am ((PDT)) That method on mine would not be worth the expense or effort really. Delrin seems to handle the back-lash issue for mine the best, but even that is now under debate on this mill, due to a lack of room for their surrounding brass bushes. I will put something in the 'photos' when I have finished all of this. Regards Phil T www.hvtesla.com ------- Re: Centec mill ACME threads to cut Posted by: "Kevin" tadpolex~xxbtinternet.com Date: Sat Sep 21, 2013 10:56 am ((PDT)) > as far as I know, it hasn't been available since. What am I missing? This link is to a supplier, but not in the size needed for this job http://www.williamhaycock.co.uk/shop/silver%20steel.htm Kevin, NW England, UK ------- Re: Centec mill ACME threads to cut Posted by: philx~xxhvtesla.com philiptuck Date: Sat Sep 21, 2013 2:03 pm ((PDT)) Kevin: I too got quite excited when I first found that link, but his sizes are certainly for clocks & not lathe screws! ------- Re: Tap & die sets [atlas_craftsman] Posted by: jmartin957x~xxaol.com Date: Mon Oct 7, 2013 7:28 am ((PDT)) In a message dated 10/4/13, jerdalx~xxsbcglobal.net writes: > Oh, yeah, IGNORE the folks who say how horrible and useless "carbon steel" taps and dies are..... They cut fine if sharp, like any tap/die, their only problem is really with being a bit more brittle, and also being harder to re-sharpen if that is needed. JT < Absolutely so, and sometimes even the brittleness is a plus. Have a horizontal mill in which someone had broken off the tightening screw in the double overarm support. It was way down deep. Tried a drill, which didn't want to cut. Hmmm, maybe it's not a screw. Nope, it's a tap. Can't drill it. Maybe it's a carbon steel tap. A couple of hits on a long pin punch and it shattered, and it fell out in pieces. A HSS tap would have been in there until I found someone with an EDM setup. They are harder to sharpen only if one waits so long that they are really dull and need a lot of metal ground off. Until then, using a slipstone or a few light passes on the wheel, they are easier. A tap is one tool that will cut even when quite dull. And that's a mistake, because you have to use extra force and that's when it snaps. John ------- Re: Tap & die sets Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Mon Oct 7, 2013 2:47 pm ((PDT)) learned 50 yrs ago to use carbon steel taps for 6X48 screws mounting target scope blocks & sights ......in the event that one snapped, it COULD BE REMOVED ....dont know when EDM was around, but i never heard of it then. FWIW ...heating to hardening state & quenching in mercury (& the fumes WERE bad news), made carbon taps GLASS hard & near as brittle...spot annealiing generally took care of case hardening. little off topic, but for those not familiar w/ removing hardened items that are frozen in place, it may be of value. the M head on the throwaway (literally) bridgeport mill had the head PINNED w/ a dowel in the vertical position ...trouble was it WASNT vertical...ground off flush, ....no threads to draw out &..blind hole... gave up trying to move it w/ a chisel biting the circumference & took the oxy /actylene to it heating to a cherry red, planning on drilling it out since i assumed it was carbon steel & wud anneal ....started drilling & it spun right out ...i had totally forgotten how i removed the remains of a rear axle bearing in the axle housing years before... just heat it up to red heat or buzz box a bead on it ...& it MUST expand, so it does in the only direction it can ...as it cools it shrinks in size EVERYWHERE (circumference & length) ...& they drop out. best wishes doc ------- Re: Tap & die sets Posted by: "James Irwin" jirwin1x~xxaustin.rr.com Date: Mon Oct 7, 2013 3:01 pm ((PDT)) I, too have had the łpleasure(?) of breaking out a 6-48 tap. Brownells said it would work, and it did w/o much trouble. Heating will make it expand. Itąs confined so it will compress against the hole itąs in. When it all cools, clearance will be there. Good tip! Jim ------- Re: Tap & die sets Posted by: jerdalx~xxsbcglobal.net jtiers Date: Mon Oct 7, 2013 4:15 pm ((PDT)) The difficulty of sharpening is mostly from needing to make sure you do not overheat it in the process. It's easy to do that with glass-hard carbon steel, even if you do not "soften" it, it may be locally less than "glass-hard" afterwards. Glass-hard" may not be always great, but if it starts that way, it should stay that way. Drawn to "straw" color, which is still reasonably hard, and considerably tougher, will wear faster. JT ------- Re: Tap & die sets Posted by: "oldstudentmsgt" wmrmeyersx~xxsbcglobal.net Date: Wed Oct 9, 2013 3:24 pm ((PDT)) I bought the cheap (less than $10) chinese sets of metric & SAE, carbon steel dies. (Said so, right there on the package!!! REALLY!) and have been replacing them as I destroy them with Vermont American taps and dies. The case and organizer fittings are good quality, anyway. I did not expect to use the original taps more than once, just got them to have a place to put the VA stuff as I got it, on a when needed/as needed basis. A local distributor, Steve's Wholesale Tools, carries the VA taps and dies individually, and in sets. I think I've got about $60 invested in good taps and dies, and $20 in the cases (with about half the original cheap taps and dies still in there). The larger taps and dies seem to work fine as seldom as I use them. The smaller ones were generally the crap everyone seems to think they would be. My workshop area has always been long on stuff, and short on stuff to keep stuff organized. After 17 years here, I'm trying to remedy that situation. Bill in OKC ------- yet another Drill & Tap size chart [taigtools] Posted by: "Paul J. Ste. Marie" taigx~xxste-marie.org Date: Mon Oct 28, 2013 9:08 am ((PDT)) After getting dissatisfied with the usual drill & tap size chart formats, I threw this together. If folks think it's useful I'll put together metric and crossover (US drills/metric threads and vice versa) versions. http://www.ste-marie.org/DrillAndThreadSizes.html ------- Re: yet another Drill & Tap size chart Posted by: "greg.mcfadden" greg.mcfaddenx~xxgmail.com Date: Mon Oct 28, 2013 12:47 pm ((PDT)) Awesome, once I figured out how it was organized, I love it. PDF or Excel would be brilliant. thanks Greg ------- Re: yet another Drill & Tap size chart Posted by: "chuck" chuckelsx~xxverizon.net Date: Mon Oct 28, 2013 6:06 pm ((PDT)) you can cut and paste it into Excel I just did just be careful mine treated the dashed numbers as dates ex: 2-56=Feb 56. Chuck ------- Re: yet another Drill & Tap size chart Posted by: "Don Rogers" Donx~xxCampbell-Gemstones.com Date: Mon Oct 28, 2013 6:11 pm ((PDT)) Guys, you can make a PDF file by using PDFprinter. The chart ends up as three pages with no clear break line. You can do a CTRL A on the page then copy and paste it into Excel, You loose the bold prints, group outlines, and color of the groups which you will have to put back in yourself. I think Paul has done great job with this chart and I for one appreciate it as is. Any other format is either going to make the print so small that it will be hard to read, or be a multi page that is hard to read. My hat's off to the work Paul has done and that he is sharing it.. Don ------- Re: yet another Drill & Tap size chart Posted by: "Paul J. Ste. Marie" taigx~xxste-marie.org Date: Tue Oct 29, 2013 12:13 am ((PDT)) On 10/28/2013 11:03 AM, felicex~xxcasco.net wrote: > I'm confused as to how you derived the thread percentages however. > They seem to differ from other charts that I think use the external > minimum rather than the internal minimum as the basis for the > calculation. Short answer is: (major diameter - tap hole) / (major diameter - minor diameter) A longer explanation... The height of a sharp V thread is: H = 1/2*(1/TPI) * tan(60 deg) 1/TPI is the base of the thread triangle, 1/2 of that gives you the base leg of a right triangle, and tangent * leg gives the height of the triangle. That works out to 0.866/TPI Unified Standard threads are 5/8th's of that height. Tap hole size is then: major diameter - 2 * thread % * 5/8H = major diameter - 1.08253 * % thread / TPI (see Machinery's Handbook, 28th ed, Tapping, p1935). (minor diameter is major diameter - 2 * 5/8H) Let Dm = major diameter, Dt = tap hole size, and tp = % thread, and you have Dt = Dm - 2 * tp * (5/8) (1/2) tan(60) / TPI 2 * tp * (5/8) (1/2) tan(60) / TPI = Dm - Dt tp = ((8/5)/tan(60)) * TPI * (Dm-Dt) = 0.924 * TPI * (Dm-Dt) You can go further and adjust that number for class of fit, but I don't think the correction matters much. Looser fits will have slightly bigger taps, and you'll get slightly deeper threads and slightly less thread engagement -- in other words, it cancels out in the end. The master is an Excel sheet, which is why doing metric and mixed charts would be fairly easy. I'll post the xls and pdf versions in a few minutes. ------- Re: yet another Drill & Tap size chart Posted by: "Paul J. Ste. Marie" taigx~xxste-marie.org Date: Tue Oct 29, 2013 11:27 pm ((PDT)) New versions of the xls and pdf with adjustments for page breaks. http://www.ste-marie.org/DrillAndThreadSizes.pdf http://www.ste-marie.org/DrillAndThreadSizes.xls ------- Re: yet another Drill & Tap size chart Posted by: "Pat Goodyear" kf6pbnx~xxgmail.com Date: Wed Oct 30, 2013 8:43 pm ((PDT)) Paul, thanks for the chart it is fantastic in whatever format. I have used both metric and imperial close enough threads several times. Last time on a antique automatic fly reel that the pivot screw broke off, best guess was 3mm .4, but a 3-48 worked close enough. I would be very interested in a crossover chart. Pat ------- gotta love those broken taps [atlas_craftsman] Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Thu Nov 7, 2013 6:19 am ((PST)) My last shop challenge was to cut 32 threads per inch on the 1.159? OD of a tube. The threaded area was .125? wide and followed by a .032? wide run out area. Beyond the run out area was a 1.300? lip. A standard threading tool hits the lip before the threaded area is reached. I used a trick taught to me a long time ago: take a Ľ-20 tap and grind off all but one point at the very end. Then shape the front of the point to have the proper relief. I then ground the end of my little boring bar so it did not extend beyond the root of the thread. This tool lets me thread right up to the lip with no problems. Sure glad my lathe can run at 28 RPM so it all happens in slow motion. Otherwise, I would have turned the lathe by hand. Rick ------- Re: gotta love those broken taps Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Thu Nov 7, 2013 4:11 pm ((PST)) i think i remember using an ummodified tap to cut an internal thread a bit larger than the tap diameter because of size constraints. FWIW ...think you cud also w/ a 32 P thrd, have ground a 60 deg point on the far left side of a regular tool bit, leaving just enuf plus a little to complete the thread....??? best wishes doc ------- Re: gotta love those broken taps Posted by: jmartin957x~xxaol.com Date: Fri Nov 8, 2013 5:22 pm ((PST)) As you remember, Doc, it works well on internal threads. Not as well on external threads, as the helix goes the wrong way. You can get the necessary clearance by rotating the tap down (clockwise) so the radial clearance makes up for any rubbing on the cutting flank. Of course, you're then changing the profile of the thread from 60 degrees to something greater. I agree that it's pretty easy to grind a HSS tool bit to thread up to that shoulder. John ------- Re: gotta love those broken taps Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Sat Nov 9, 2013 2:49 am ((PST)) Doc, I recall this trick from a Bedside Reader. They put a sliver of hardwood in a tap flute to offset it by a few thou. I could never get it to work because the wood crushed. Maybe brass would do better. The cutter point I got with the modified tap sure is tiny. I doubt I could have ground it the 60 degree point free hand as well as it was machined by the manufacturer. Besides, I have plenty of broken taps ;-)) Rick ------- Re: gotta love those broken taps Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Sat Nov 9, 2013 2:51 am ((PST)) John, The thread that I cut looks good when I put a 6-32 screw against it. But I really won't know if it works until the mating part screws on. There sure isn't much meat in that thread. Rick ------- Re: gotta love those broken taps Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Sat Nov 9, 2013 9:51 am ((PST)) Rick ....yes i was unclear ...i used the tap as a "chaser" to cut a larger diameter ...set the lathe to cut the TPI & used the tap as a multi point tool .....trying to remember why ...i think the hole diameter was too small to use a boring bar? no boring tool that small? or didnt want to grind down a lathe bit to make a small boring tool ....anyway i do remmber that it worked.....! i remember abt packing the tap to enlarge the thrd a bit ...never tried it ..maybe rock maple wud not crush???/...aluminum? .....one more "tip:" that needs to be subjected to scientific repeatabilty testing ..sounds like your bailiwick ????///he he .....anyway we now can reinforce our belief that you are an honest man .,..admitting to a plethora of broken taps... he he. i have made boring bars from broken end mills, & they work well..... never thot abt using a broken tap ...hmmmmm....grind off thrds, groove gives built in rake, hmmmm..... was given a fairly large shop-ground worked-over endmill last month ...the middle was 1/2 ground away on one side ...& a boring configuration ground on the end of the same side that was ground away in the midddle ...took a second look to figure that it was ground to make an internal recess. abt a dozen years ago, doug King visited here for about 10 days of non stop shop tiime ...he has since retired early, he had 45 machinists & a pile of millwrights under him keeping a VERY large paper mill running in canada...having never had formal training, it was a revelation watching him work & instruct ...actually getting a friendly light "klop auf dem koph" (slap on side of head) after telling me not to "cut corners'.... anyway ....he made a B&S 9, 1-1/4 inch left hand arbor on my 1895 Reed w/ the ancient taper attach that attached to an xtra slide under the x slide .....went right at it like he had been using it for years....result was an arbor & i am sure there was cancellation of errors in spindle, arbor whatever, ...but an indicator showed less than a thou run out at the end.....i WAS impressed. got carried away, but point here was, in less than 5 minutes (actually less than 3 min., while i was looking for a boring bar).. he took a lathe bit & ground a boring bar to use in boring out the nut for threading. FWIW ..he showed me the "britt" method of cutting acme & square thrds ... set the compound in line w/ the lathe axis ..grind a bit undersize, but correct angle, & cut the thread to full depth ...then advance the compound a few thou at a time on both flanks till the "fit " is as desired ...... cutting the thrd this way takes more time, but i got less lash than using full size ground bits, or tap..... this solves the very tedious task of grinding a HS acme /square bit EXACT. FWIW #2...for the very LEAST lash, take a cleanup cut on the screw to eliminate wear in the center, & then cut the nut usinng the above method. best wishes doc -------- Re: gotta love those broken taps Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Sun Nov 17, 2013 5:02 am ((PST)) Doc, Sorry for the very slow response. Been on vacation enjoying time with my granddaughters. I do have a LOT of broken taps but they are from my novice days. Now that I tap with one of my alignment fixtures, I rarely break a tap. I’ve also (mostly) learned to notice when the tap is dull so I don’t twist it in half. A tap modification trick I picked up, maybe from a Bedside Reader, was to use a Dremel with cut off wheel to cut a groove in the OD slightly smaller than the OD at the root of the thread. The groove is between the square end and the start of the flutes. If you break the tap, it should break at this weak point. Then you have plenty of shank to grab in order to unscrew it. Neat idea – just never tried it. That visit from Doug King sounds invaluable. Too bad there wasn’t some way to have captured it all, other than in your head. I think we addressed the cutting of threads with a simple plunge cut in that monster article on threading we did a few years ago: http://rick.sparber.org/spt.pdf I still have another iteration to make on this article involving insights from Andy Wander. Rick ------- Tap for making spindle threads [atlas_craftsman] Posted by: jerster1959x~xxyahoo.com Date: Tue Nov 19, 2013 3:25 pm ((PST)) I'm sure this question had been asked. maybe someone can direct me to the forum or file. but here goes. I want to reuse the chucks that U have on my old HF 9x20 lathe for the Atlas Craftsman. I need to make new backing plates. I have found 1 1/2x8 taps but usually in pipe threading. which type of TAP should I get. UN, UNR? in 1 1/2x8. ------- Re: Tap for making spindle threads Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Tue Nov 19, 2013 3:30 pm ((PST)) You don't want to use a tap. It will likely be off center. Cut them on the lathe. It is not that hard to do. Besides, you can order back plates for what you would probably pay for a tap. Scott G. Henion, Stone Mountain, GA Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 Welding pages and homemade welder: http://shdesigns.org/Welding ------- Re: Tap for making spindle threads Posted by: "jerry Herrera" jerster1959x~xxyahoo.com Date: Tue Nov 19, 2013 3:35 pm ((PST)) Thanks Scott. I've been trying to setup my lathe for that size thread. just has not been successful. but If using a tap's not the correct way, then i'll continue to try and figure it out. Question. when cutting threads I understand the change gears but is there a certain speed that I should set the lathe to. ------- Re: Tap for making spindle threads Posted by: "Eggleston Lance" wheezer606x~xxverizon.net Date: Tue Nov 19, 2013 3:41 pm ((PST)) Fast enough to cut smoothly, slow enough for you to see what's happening and control the half nut lever. Be sure to cut a run-out area at the back of the thread. lance ------- Re: Tap for making spindle threads Posted by: "Scott Henion" shenionx~xxshdesigns.org Date: Tue Nov 19, 2013 3:43 pm ((PST)) Usually as slow as possible. I used the back gear and slowest spindle speed when I made my ER40 collet chuck. Sorry, i forgot to take pictures of the steps cutting the threads. Slow helped stopping in a defined area. Scott G. Henion, Stone Mountain, GA Craftsman 12x36 lathe: http://shdesigns.org/Craftsman12x36 Welding pages and homemade welder: http://shdesigns.org/Welding ------- thread forming question [atlas_craftsman] Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Tue Dec 24, 2013 12:30 pm ((PST)) I have been studying the Unified Screw Thread tables in Machinery's Handbook in order to better understand the details. I usually single point cut threads until a go/no go gage says I'm done. I want to better understand this subject. I can see that to cut an external thread, I would first turn the OD to be within the Major Diameter spec for a given nominal size, TPI, and thread class. Easy enough. Then the table specifies pitch diameter. I understand that this is the diameter at which the width of the recess equals the width of the ridge. MH does not say that it is when the width of the recess equals half of the pitch. So, to me, this is saying that the exact pitch cannot be trusted to be ideal. One way to measure/calculate the pitch diameter is the 3 wire method. But as far as I can tell, it assumes a perfect TPI and a perfect 60° included angle on the flanks of the thread. I do not see any spec in MH for the tolerance of the TPI or the included angle. So is it customary to assume perfect TPI and included angle? If so, am I correct in assuming that you simply feed in the cutter until the pitch diameter is in spec (and the root is correctly formed)? Thanks in advance, Rick ------- Re: thread forming question Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Dec 24, 2013 3:15 pm ((PST)) BECAUSE there is tolerance on the major diameter, & unintended tolerance in the angle grind of the bit, the perpendicularity of bit placement, AND the truncating, never mind the flex in light lathes & the variability of getting the exact doc applied, (like how many times did you take a cut w/out adding on, a clearing cut? & WHERE ?) the only possibilities are to thread to a go/nogo gage OR to the mating part. the gage maker has to work to supposed absolutes, & must take the pitch diameter to be determined by fixed parameters...most probably an adjustment of the V thread pitch diameter to conform w/ the adjusted unified thread depth /ht ......but that is my supposition, not based on knowledge ...research into thread gage makers may provide the answer. it is intereting that machinery's handbook w/ ALL the verbiage to wade thru bearing little relation to home shop, does not think the origination of pitch diameter to be important enuf to be dug out. sounds like a thesis subject for a doctor of engineering ......i do know how something can drive one 1/2 crazy searching for understanding or maybe an answer....have had many a nites sleep delayed running things over & over in my head ....(the 30 degree compound travel being a jagged line for one)......but thanks be, this is not one of them. PRACTICALLY, it is still, make the thread to FIT. gage or part....if producing to a spec, one needs a gage. merry xmas doc ------- Re: thread forming question Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Tue Dec 24, 2013 3:46 pm ((PST)) Doc, Thanks for your usual sage advice. At the moment, my head is into theory, not practical concerns. I've always used a go/no go gage to test my threads. After puzzling over every column in the UN thread table all day, I think it is starting to sink in. As I said, I was unable to find any reference to TPI or 60° form tolerances. I did find mention of maximum thread length. If I read it right, there is a limit to how many threads can exist in a nut and it is 15. Maybe this is the hint that when TPI is off a little, it won't catch up to you until the 15th revolution. When my mind is clearer, I really want to fully understand this limitation. I have reasoned out, maybe erroneously, that since 3 points define a plane, a nut suspended on a bolt is contacting at only 3 points. If it contacted at more points, it would mean those extra points are EXACTLY on the same plane. Not likely. If the nut is pressing on a surface and is tight, then the nut might only contact the bolt at a single point. The nut's position is dictated by the surface and the threads of the nut define which point on the bolt is touched. This does assume no deflection of the threads. Rick ------- Re: thread forming question Posted by: wa5cabx~xxcs.com wa5cab Date: Tue Dec 24, 2013 9:16 pm ((PST)) No. If the circularity is perfect and the thread form and pitch are exactly the same in both screw and nut, given that a point, by definition, has zero dimensions, the nut and screw will contact at an infinite number of points over the length of the nut. The fact that three points define a plane does not mean that two planes touching at three points are only touching at three points. They will be touching at an infinite number of points. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: thread forming question Posted by: "Rick AOL" rgsparberx~xxaol.com Date: Wed Dec 25, 2013 3:25 am ((PST)) Given your assumption that the mating surfaces are perfectly congruent, I agree that they will touch at an infinite number of points. I was assuming the general case of non perfect surfaces. Rick ------- Re: thread forming question Posted by: "Guenther Paul" paulguenterx~xxatt.net Date: Tue Dec 24, 2013 4:29 pm ((PST)) Rick. You can use a standard micrometer and piano wire to check the depth of the thread but if you want to spend the bucks there is a micrometer made to measure threads. GP ------- new artical: Understanding Nut and Bolt Specifications [atlas_craftsman] Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Wed Dec 25, 2013 6:35 am ((PST)) This article, intended for those new to our hobby of metalworking, deals with nut and bolt thread specifications. It is based on material found in the Machinery's Handbook. I attempt to explain thread class, thread allowance, major and minor diameters, and pitch diameter. If you are interested, please see http://rick.sparber.org/nbo.pdf Your comments and questions are welcome. All of us are smarter than any one of us. For the full index of my articles, see rick.sparber.org. Rick ------- Re: new artical: Understanding Nut and Bolt Specifications Posted by: "jo barden" jobarden422x~xxmsn.com Date: Wed Dec 25, 2013 8:50 am ((PST)) Hi Rick. You are allowed to have a break at Christmas you know! your bit is very good but living this side of the pond I would also mention BSW, BSF, BSC, BA Metric Coarse and Fine as well as BS gas oh and some weird ones like taper threads. I find the "Model Engineers Handbook" by Tubal Caine (not the guy off the internet) and "Zuess Tables" very informative. Happy Holidays Jon ------- Re: new artical: Understanding Nut and Bolt Specifications Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Wed Dec 25, 2013 11:33 am ((PST)) Jon, What makes you think that writing articles isn't how I take a break ;-)) I own a few of Tubal Cain's excellent books but not this one. It is on my list now. Thanks! Rick ------- Re: new artical: Understanding Nut and Bolt Specifications Posted by: azbrunox~xxyahoo.com Date: Wed Dec 25, 2013 10:40 am ((PST)) Rick, Thanks for doing this. I just read both files. Are you able to determine the range of diameters for various classes mathematically? In other words, say you want an arbitrary thread like .215-36 with the usual 1/8 flat on the bolt and 1/4 flat on the nut. What are the ranges for turning the bolt and boring the nut for each class fit? On another point, it's common to buy internal and external threading tools that are cut to a sharp V. I would suspect most people who do single point threading use such tools, which means a necessarily deeper cut from the 0 point. And related, what are the issues related to using a tool with a flat on the tip... now you're cutting on two faces of the tool. Regards, Bruno ------- Re: new artical: Understanding Nut and Bolt Specifications Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Wed Dec 25, 2013 1:22 pm ((PST)) Bruno, Funny you should ask. At this very moment I am trying to add to my web site two spreadsheets developed by my friend, Mark Cason. They will let you take any arbitrary diameter and generate the essential values needed to form the thread. I just need to figure out what is wrong with my HTML coding. I usual post .pdf and sometimes .xls. But the spreadsheets are in .xlsx and .ods formats. I grind my own threading tools from HSS using a 'fish' to check the angle. As long as I grind slowly, it is easy to get the angle close. Blunting the end to give the proper root is easy although far from precision. I never had any problem cutting with it. Recall that all cuts are light when threading. Rick ------- [atlas_craftsman] new set of spreadsheets: calculate thead parameters for any diameter Posted by: "Rick Sparber" rgsparberx~xxaol.com Date: Wed Dec 25, 2013 3:01 pm ((PST)) My good friend Mark Cason developed a set of spreadsheet calculators that let you input the basic diameter of a fastener and it will return all parameters needed to form the thread. Although intended for standard diameters, it works as well for any diameter with only a minor bit of fuss. The spreadsheets are in LibreOffice and Excel 2007 formats. See the ReadMe file at http://rick.sparber.org/tcmc.pdf The LibreOffice file is at http://rick.sparber.org/ASME_2A_2B-Inch_Thread_CalculatorVersion2.ods The Excel 2007 version is at http://rick.sparber.org/ASME_2A_2B-Inch_Thread_CalculatorVersion2.xlsx Excellent work Mark! Your comments and questions are welcome. All of us are smarter than any one of us. For the full index of my articles, see rick.sparber.org Rick ------- Re: Metric Threading [atlas_craftsman] Posted by: mplieb1x~xxgmail.com Date: Mon Jan 13, 2014 5:02 am ((PST)) If you are changing end gears, there is an online calculator that figures out what gears to use from your existing set. There is an option to choose "other lathe" and then you put in the TPI of your lead screw, the gears in your existing set, and the desired threading outcome. I haven't tried it yet, but it looks promising. http://littlemachineshop.com/Reference/change_gears.php Regards, Marc ------- [Remove broken tap] Old tip for an Newbie -- it really works [Taigtools] Posted by: terryallen2x~xxcox.net valkcapt Date: Wed Jan 15, 2014 1:26 pm ((PST)) I decided to do the bearing modification on my steady rest. But when I was tapping for a 5-40 thread in one of the three brass rods in the rest, I broke the tap. I had heard that tap extractors didn't work, and I didn't want to have to mill a replacement part. So discovered what is said to be an old remedy for broken taps: putting the part in boiling water saturated with Alum. I got the pot boiling at the start of King Kong, and by the end of the movie, the broken tap was completely gone, and the hole was clean as a whistle. I had to keep tending the pot and replacing the water every 10 minutes, because the water evaporates so fast. You guys probably already knew this, but for me it was nothing short of a miracle. One more thing. It only works on non-ferrous materials. ------- Re: Old tip for an Newbie -- it really works Posted by: "Pat Goodyear" kf6pbnx~xxgmail.com Date: Sat Jan 18, 2014 10:10 pm ((PST)) Ok the trick I use is a can of quick freeze and a small center punch or pin punch, automatic center punch works the best. Spray the tap with quick freeze until a frost line forms, smack the tap with the punch and hammer and the tap will shatter, pick out the pieces and you can re-tap the hole. Pat ------- Re: Old tip for an Newbie -- it really works Posted by: "Caparo" caparox~xxsaltmine.org.uk Date: Thu Jan 23, 2014 7:57 am ((PST)) Hi, does not matter what the tap is made of if you just weld a T handle to the broken shank. The heat breaks the surface grip and the tap is simply screwed back out and since the tap is now softer does not damage your hard work. I do this a lot with broken studs in motorcycle & car engines too. TTFN Caparo ------- left hand threads [atlas_craftsman] Posted by: "Rgsparber" rgsparberx~xxaol.com Date: Mon Jan 20, 2014 2:42 pm ((PST)) I'm trying to get my head around the idea of single point turning left handed threads. Wouldn't the lathe run in reverse? Or does the leadscrew run in reverse? Thanks in advance, Rick ------- Re: left hand threads Posted by: "Art Eckstein" art.ecksteinx~xxwirelesshometown.com Date: Mon Jan 20, 2014 2:57 pm ((PST)) Rick, IF I were going to cut left handed External threads on my lathe, I would: Cut from the Chuck towards the Tailstock. Set the compound to ~29° to the left of center. Have a recess in the stock so I could engage the carriage at the correct point. Run the lathe in the NORMAL direction so I would not have to worry about the chuck unscrewing from the spindle! Art Country Bubba ------- Re: left hand threads Posted by: "Jon Elson" elsonx~xxpico-systems.com jmelson2 Date: Mon Jan 20, 2014 3:02 pm ((PST)) If the lathe is running in the normal direction, then the leadscrew needs to run backwards, so the cutter moves AWAY from the chuck. With threaded chucks, this is the way to do it, otherwise the chuck could unscrew. Jon ------- Re: left hand threads Posted by: "Rgsparber" rgsparberx~xxaol.com Date: Mon Jan 20, 2014 3:07 pm ((PST)) Art, Thanks for the help. I'm glad I don't have to run the spindle in reverse! Rick ------- Re: left hand threads Posted by: wa5cabx~xxcs.com Date: Mon Jan 20, 2014 3:10 pm ((PST)) I agree. Except that I would turn the compound around so that it was still pointing in the direction of carriage travel (i.e., toward the tailstock) so that as you advance the compound between passes most cutting would be on the side of the V that you were moving toward. Robert D. ------- Re: left hand threads Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Mon Jan 20, 2014 8:15 pm ((PST)) FWIW. if the chuck is turned up to the shoulder w/ a lite BUMP it is highly unlikely that it will unscrew w/ the lite thrd cuts & lo speeds ....mine never has yet in 50 + years ....once you know what you are doing, the specter of a chuck coming loose almost vanishes ...& NO, you dont run a THREADED chuck at 2000rpm & cuts of .125 inch. when they started using 5 hp, carbide & high speed w/ heavy cuts, they went to LOO taper & D4,5 whatever spindles. when cutting a rt hand thread, running the spindle in reverse & the carriage moving towards the t/stock is valuable for threading AWAY from a shoulder (rather than up to a shoulder), particularly on an inside thread where one cannot see as well as desired...(thrd bit must be upside down unless threading from a rear tool post). best wishes doc ------- Re: left hand threads Posted by: "Carvel Webb" carvelwx~xxabsamail.co.za Date: Mon Jan 20, 2014 11:42 pm ((PST)) Rick, To complete the options one can run the spindle backwards and thread from right to left the normal way, especially if you have some chuck clamping arrangement such as used on the Emco lathes, although the possibility of the chuck coming unscrewed at low speeds and low cutting forces is I think somewhat overrated. You do however then either need to mount the threading tool upside down, or mount the tool in a rear tool post holder. Mounting the tool upside down in the front has the advantage that it is less inclined to dig in, as it can lift out slightly at the point that it would jam given the play in the cross slide / top slide assembly. Regards, Carvel ------- Threading tool [atlas_craftsman] Posted by: "Bradley" peacehelotesx~xxsbcglobal.net Date: Mon Jan 20, 2014 1:54 pm ((PST)) Does anyone have a source for the round Atlas/Armstrong thread cutter with the 5/16 mounting hole? We used to get them here from Alamo Iron Works but they don't carry anything like this anymore as well as on line from Wholesale Tool. Brad ------- Re: Threading tool Posted by: brogers9941x~xxsbcglobal.net Date: Tue Jan 21, 2014 10:43 am ((PST)) I have used old files as a source of carbon steel for tools and knives. I made an inside single-point threading tool using an old file and it works good. When I first got my 12x36 lathe, I filed a similar post to your own. I think that Doc suggested that I make my own cutter. But at that time I didn't know where I could get a 1/8" x 3/4" piece of carbon steel. Eventually I found that old (dull) files are a great source for carbon steel. Making a new wheel from a file should be easy. It isn't a very high precision or demanding project. First, I would snap off an appropriate- sized piece using a vice and a hammer. Then, I'd take out the hardness by heating to the bright red (Curie) point and letting it cool SLOWLY. After it is down to room temperature you can check it's hardness (or lack of hardness) by stroking it with another file. If the sharp file skitters over the old file piece without cutting, then you did something wrong. If you can file it, you did it right. Then it's just a matter of grinding off the file grooves and rough shaping it to about the right size. Drill a hole in the center and fasten it to something like a hex coupler and chuck it up in your lathe. If you want better concentricity for turning (probably not really needed for this application), drill and tap a piece of hex stock and make your own (more precision) coupler. Then turn the disk to the right diameter and profile. When you're done, grind off 1/4 of the disk (like taking a pizza-shaped slice out) to match the shape of the original. To get a real sharp edge, perhaps finish with a fine/sharp file and stone. If you have access to a mill that would be another alternative. But you still probably want to stone it. When you get it to the right shape and sharpness, then you may want to consider re-hardening it. If you plan on threading aluminum, it might not be needed. But if it is harder, it will stay sharp longer. In crude terms, that means heating it up again (red/Curie temp) and quenching it (probably old drain oil is preferable to water). That will make the tool super hard but brittle. But if you are doing single point threading and taking light cuts, it probably doesn't matter that it would be brittle. Just don't drop it on the floor. If you're a purist, you can always re-temper it (i.e., take out some of the brittleness). When I do that, I first shine up the metal which takes off the oxides that formed during the heating. Then I would carefully/slowly heat it with a propane torch until the shiny metal just starts to turn a straw color. At that point, remove the heat and let it cool. A purist would do all of this with a lot more finesse, but this application is very forgiving/non-critical. It is a good project for a beginner. I'm glad that Doc suggested I do this several years ago. ------- Re: Threading tool Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Jan 21, 2014 2:43 pm ((PST)) FWIW ..i havent had the need yet, but did think abt what i wud do if i needed a circular bit .....when i saw the armstrong price many years ago, i ddecided i wud take a piece of 0-1 or w-1 & mount it on a mandrel ... turn up the 60 deg angle & mill / grind/ saw / out the outside contour ... at the ususal thrding speeds & feeds, a hardened piece of carbon steel, drawn to abt 375 for 0-1, 0r 410 for W-1 in the oven, shud work fine ... QUENCH it VERICALLY. best wishes doc ------- Re: Threading tool Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Jan 21, 2014 5:58 pm ((PST)) till you see a pic .....this is a circular piece w/ a central hole, bolted to the front of a 3/8 & 7/8 bar ....the disc is turned so that the circumference is beveled to a 60 deg included angle ....there is a horizontal cut at the center line into the disc abt 1/4 way in where it connects to a vertical cut, these two cuts take OUT a rt angle chunk so that the front edge of the disc is now a thrding bit ... since it is at center line, there is clearance below ...as it wears you rotate the disc & grind the top surface flat again.....there is also a lug at the rear of the disc w/ a threaded hole for a bolt which bears on the rear of the disc to help anchor it from rotating during use. ..very useful ...abt all i use unless i need a gooseneck holder for either very coarse thrds or "old school" thrding straight in on my antique Reed 14 inch which was built w/out a compound ... having a rise & fall xslide & an xtra slide underneath to attach to the taper attachment, leaving insufficient room for a regular compound.....i thot i needed one so i built a "side saddle compound (slide ways are vertical rather than horizontal, occupying less height which bolts to the tool post T slot... but have never used it after testing .....w/ a gooseneck holder i get clean threads cutting straight in ....reckon i shud use it at least one time! best wishes doc ------- Re: Atlas Metal lathe on Craigslist [atlas_craftsman] Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Thu Feb 13, 2014 1:49 pm ((PST)) white5415 wrote: > Yeah it does look cool......LOL What I hate is jumping back and forth between cutting a 3/4" 16 thread and then back to a fine feed rate for turning....... < John FWIW ...many of us even some who have a QC box ..still feed manually xcept on very long cuts ....besides saving a threading tear down, it saves the leadscrew accuracy / 1/2 nut wear when you DO have a QC. my 1895 Red 14 inch has fixed 3 speed feed by pulley drive & a FEED screw ...so changing thread set ups usually only means i need to change one gear...when that is inadequate, there is a compound gear mounted that just needs to be slid into the gear train ......it goes so fast, that i do not really miss a QC box......but you are correct, the combined thread & feed on the bench lathe is a real PIA, atlas, crftsmn, SB & Logan, but if you ever work on antique firearms, metric, or other exotic stuff, you will love a loose change. best wishes doc ------- how to use "Myford Thread Chaser" [myfordlathes] Posted by: lothar-kielx~xxarcor.de l_doring Date: Sun Feb 16, 2014 6:56 am ((PST)) I'm working already 35 years with lathes and a ARBOGA mill but have no idea how to use "Myford Thread Chaser" which are offered under the item No. 331126187198 on EBAY-UK. Are they for cleaning old rotten threads or to produce a new one in steel, brass or so? Are you just holding them by hand or are they clamped in a holder - they look quite unequal on surface. Could somebody please explain the usage? Have fun in your workshop Lothar ------- Re: how to use "Myford Thread Chaser" Posted by: "Bob Hamilton" bobx~xxhamilton-bob.freeserve.co.uk Date: Sun Feb 16, 2014 7:35 am ((PST)) Hi Lothar. There are at least two types of thread chaser. A machine held one and a hand held one. There are internal and external. They have the correct form for the particular thread size that you are making. That is, the angle and radius for a Metric or imperial chaser of a particular pitch as marked on the chaser. Note, the diameter of the thread is immaterial. They are really, in my opinion only used to finish or tidy up threads, after screw cutting with a single point tool, or when a thread has been damaged slightly. External hand chasers are quite handy for use on a lot of stuff where absolute accuracy is not the prime consideration. They are used with a large handle and a rest similar to wood turning. Internal hand chasers are less used as it is difficult to hold them adequately. Both internal and external machine chasers need to be used very carefully. I base the above on 100 year old practice, not modern CNC type machines. Bob ------- Re: how to use "Myford Thread Chaser" Posted by: dickmx~xxwaitrose.com crawleystones Date: Sun Feb 16, 2014 9:56 am ((PST)) The "old boys" used these extensively for threading on plain, non- screwcutting, metalworking lathes, but they are probably obsolete for metalwork these days. However, for wood turning, once you get the knack, they can be invaluable for making threaded lids for jewellry boxes and the like, or even for wooden screws. But if making lids, always thread the female portion first - you can always make the male portion smaller to fit, but it's not easy the other way round. DAMHIKT. Dick Morris ------- Re: how to use "Myford Thread Chaser" Posted by: "Andrew Curl" methuselahx~xxntlworld.com Date: Mon Feb 17, 2014 2:42 pm ((PST)) Lothar, chasers (or "combs" depending on your age/ location) are used as a hand tool, to produce the correct crest and root form after screwcutting with a vee tool. There are those tales of chaps who can strike a thread with them freehand, but for we mere mortals, they are strictly for finishing only! You don't see them often these days, as full-form carbide insert tooling has become ever more common. I haven't used one for about twenty years now. For external threads, most people make up a handle to take a coventry diehead chaser anyway. Andrew UK ------- Re: how to use "Myford Thread Chaser" Posted by: jonathanagibbsx~xxgmail.com jonagibbsuk Date: Tue Feb 18, 2014 4:12 am ((PST)) Hi Lothar, As with many things on Ebay the Myford tag is just to catch those unwary punters searching for all things Myford. As a hobby woodturner, I've dabbled, like Dick has, in thread chasing in boxwood and those chasers would be ideal for working in wood. You can also use them for chasing zinc, tin/pewter or maybe brass too from scratch or for cleaning up worn threads or for rounding over the crests on Whitworth threads. If you bought them in error wanting to use them for metalworking then I'd separate them into pairs (male & female) and sell them on Ebay again one at a time. In the 12-26 TPI range they've got to be worth a tenner each pair to a woodturner IMHO. HTH Jon ------- Date: Tue, 18 Feb 2014 18:24:59 -0700 From: "annewatson" Subject: [OldTools] 12-20 tap and die for Stanley plane 1.. As I mentioned before my brother and I have been messing around with old woodworking planes some of which are in pretty bad shape, but the price was right. The last one in had pretty bad threads on the rod for the tote. A search on EBAY showed one for 35.00. Kinda expensive for a one time usage. It seems to me that someone could just make one in the right length and offer them for sale. Or even better maybe some one who had an extra one would be willing to sell it. With all the interest in old wood planes you would think the taps and die would be more available. ------- Date: Tue, 18 Feb 2014 17:16:43 -0900 From: Phil Schempf Subject: Re: [OldTools] 12-20 tap and die for Stanley plane Anne - There is a guy on eBay that goes by Nicobie that sells 12-20 dies, also $35 (hope I'm note confusing myself re: the $35 you mentioned). Once you get some suitable brass rod stock you could make a bunch of rods for <$35 each. Phil ------- Date: Tue, 18 Feb 2014 18:28:40 -0800 From: "Adam R. Maxwell" Subject: Re: [OldTools] 12-20 tap and die for Stanley plane You can use a 1/4-20 split die to make 12-20 threads. I can't find BugBear's original post on it, but this one is good: http://swingleydev.com/archive/get.php?message_id=156732 Adam Port Angeles, WA ------- Date: Tue, 18 Feb 2014 18:31:08 -0800 From: James Thompson Subject: Re: [OldTools] 12-20 tap and die for Stanley plane An adjustable die, one that is split in half, and sometimes even only cut through on one side, can be adjusted down to cut the desired thread. I use a normal 1/4"-20 die set tight, to cut the initial thread, then use a squished down die for the final cut to reduce the diameter to #12. It is not rocket science. ------- Date: Wed, 19 Feb 2014 09:01:50 +0000 From: paul womack Subject: Re: [OldTools] 12-20 tap and die for Stanley plane Here's an archive of my old web site: ://www.geocities.com/ply bench/tour.html#stanley_threads > but this one is good: > http://swingleydev.com/archive/get.php?message_id=156732 I think this is the original: http://swingleydev.com/archive/get.php?message_id=101860&submit_thread=1 BugBear ------- Date: Wed, 19 Feb 2014 15:35:58 +0000 From: "Stager, Scott P." Subject: Re: [OldTools] 12-20 tap and die for Stanley plane Years ago - maybe as many as 10 someone on oldtools had a run of custom 12-20 tap/die sets made. I believe the quantity was based on commitments to purchase from oldtools members. As I recall the price for the set was $75. So $35 is a good price. It is my understanding that making such things are within the skill set of a capable machinist. I'm not a machinist nor have I ever attempted to personate one, but I do recall that technically these are a bit different than the originals. Something about cut rather than rolled threads. Maybe something about the shape of the threads also? I like the split die idea others mention. I have no idea where to find such things - whether they are still manufactured, or if one needs to keep an eye out for old sets. Scott ------- NOTE TO FILE: A conversation began in the Metal_Shapers group in Feb 2014 about restoring a metal shaper and that thread can be found in its entirety in the text file here called "Metal Shaper Repair General". Part way into that conversation, there was a discussion about repairing or replacing or making a lead screw; so that portion was copied to this "Threading (Lathe and Otherwise)" text file. So too was a later tangent about threads on rifle barrels. ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 7:58 am ((PST)) Got up at 0'dark-thirty, and started re-assembling my Lewis Shaper. So far, I've had no trouble finding the parts, which is a minor miracle in itself. ;) While I'm doing this, I'm measuring the bits and pieces I think of as consumable non-standard hardware, i.e., gibs, and bits and pieces I can't get at Lumber II or a decent hardware store. I think I'm going to need to replace the leadscrews, sooner or later, as they are, I believe the technical term is "buggered up" a bit. The original builder or a later restorer used the manufacturer's specified set-screw collars to hold them in place, and they've obviously slipped and then gouged the heck out of the threads near the handle end of the leadscrew. So part of my project today, while I'm working on the shaper, is to clean up the shop enough to get to my lathe. I can't afford a 5/8"-10 tpi LH square-Thread tap and or die, but I do believe I can make them. With enough practice, anyway. ;) Double that as I think one of the leadscrews is 1/2"-10tpi LH Square-thread. Currently both are soaking in Evaporust so I can't check them right now. I got the power supply for the DC motor, but I would rather use it on my bandsaw, I think. Will have to revisit that when I get to looking a what it takes to modify the drill press motor and pulleys I plan on using for the shaper. Gotta do the math and see what speeds and feed rates I'll get before I can make the decision. I knew that there WOULD be math when I got back into this machining stuff. Time to learn it a bit. Wish me luck, guys, I'm gonna need it! Bill in OKC ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: dkinzerx~xxgmail.com don_kinzer Date: Sat Feb 22, 2014 10:10 am ((PST)) >I think I'm going to need to replace the leadscrews [...] I had to replace one of the leadscrews on my Brodhead-Garrett. I believe that it was 5/8-10LH also and I bought a length from a supplier like MSC. I do have some left over. If you are interested, I'll confirm the size, pitch and length. Don Kinzer Portland, OR ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sat Feb 22, 2014 10:11 am ((PST)) Bill, Square threads? Are you positive? In England they use to use square threads but they are difficult to make especially for a long screw. Much more common would be Acme, which is 29 degree included sides. Even Acme threads are not for the rusty or "all thumbs" machinist. The only square threads I've seen or heard of in the U.S. is rifle breeches, and I think those are Mausers I've read that of. Well, any gunsmith can do that, it's only an inch or so and fine threads. I once owned a Lewis long ago, and would have noticed, but the builders are the ones who decide how they are going to make them so every one is different. If you do make a new feed screw you would do well to add a key everywhere the original had a setscrew for torque resistance, like a handle or gear terminus. I can't say for sure because I can't see it but if you follow common engineering practices you will be way ahead. When you do have to have a setscrew lock down on a screw (Never on an Acme or square in my experience, only on 10 TPI or finer 60 degree threads) a small piece of brass or copper at the bottom of the setscrew hole, preferably running the tap through to cut threads in the brass or copper face so they won't damage the threads, is the way to do it. But I assume you are talking about an area that is turned down? If an area of a thread is turned down at the end and a collar or handle or gear is placed there (Still really bad engineering) you may want to dimple the turned area to receive the setscrew point. I wish I could see this shaper, but I remember I was not impressed with the Lewis I had so I gave it to a friend. I assumed the poor engineering I saw was individual high school shop shortcuts I was seeing. No reason to not redo it right if you have to do it over anyway. (Smile) Glen ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "JRWilliams" jrwillmsx~xxhal-pc.org Date: Sat Feb 22, 2014 11:17 am ((PST)) Square threads -- check the US Springfield and M1 Garand rifle barrels. ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "William R Meyers" wmrmeyersx~xxsbcglobal.net Date: Sat Feb 22, 2014 11:20 am ((PST)) Don & Glen, Well, they're both definitely 5/8"-10tpi, but I am not certain about the square thread. I looked closely at them, and they do appear to slope a bit at the sides, but I'm not sure if it's wear or what. They're deeper than the 10tpi notch on my Starrett ACME thread guage, but it's for checking cutting tools, not threads. I have the gauge because I've been planning on doing ACME threads for a very long time. This is the first time I've used it in the 3 or 4 years I've owned it. Went looking for a cheaper US or import gauge at my local supply place, and they'd had someone special order it, and then not pick it up. After nearly a year, they wanted it gone, and gave it to me for what the import would have cost. It is the only GOOD machinists tool I own, so far. Well, not counting some damaged & salvaged Starrett rules. The threads do look more like the square thread on my broken vise, and on a couple of chinese drill vises I have, one of which came with the shaper. Not exactly square, either, but maybe not as slope-sided as the ... Just realized I DO have an object with an ACME thread to look at. The Atlas MF mill uses ACME leadscrews on its table. Yes, I'm afraid they're ACME screws. Guess I have to learn soon. I can use them as-is, there are just areas of the screws I'll have to avoid until I can get new leadscrews made so this isn't a show-stopper. Hmmm. Now I have to learn to thread, and on a challenging thread form. ;) Don, how much of that screw-stock do you have left, and how much would you want for it. I'm in 73115 zipcode, if that helps for figuring shipping. Oh, and is it left or right-hand thread? Bill in OKC ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 11:24 am ((PST)) > Square threads-?? check the US Springfield and M1 Garand rifle barrels. Wish I had one to check. My Springfield '03-A3 was stolen over 22 years ago, and I was unable to replace it, and I've never owned a Garand, although I'd sure like one. ;) One of my interests in metalworking is using it for gunsmithing. Got a long ways to go, and a lot to learn. Bill in OKC ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sat Feb 22, 2014 2:25 pm ((PST)) I do think I mentioned rifle barrels. ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sat Feb 22, 2014 2:25 pm ((PST)) Bill. Any thread pitch gage will work with acme threads for pitch. Glen ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sat Feb 22, 2014 2:37 pm ((PST)) I was very surprised to find a square threaded lead screw on my English lathes recently after buying them (I need to look and see if the feed screw is square too). The reasons for motion transmitting screws to be acme instead are many and important. I really see no need for square threads on anything but I could be convinced otherwise if proven wrong. An acme screw is every bit as strong as a square thread, much much easier to cut accurately for either a leadscrew, for a lathe, or a feed screw on a mill or shaper or lathe cross slide, in addition an acme screw is self centering. There are threads that are stronger than either type, a buttress thread comes to mind, and big guns use those. I've always wondered why Mauser used square threads, and, of course the Springfield was a Mauser design, stolen I think I read, or did they ever pay royalties? ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "William R Meyers" wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 2:42 pm ((PST)) So will a ruler, Glen. Just count the number of bumps in an inch, or a centimeter. I did get & retain that much from machine shop and mechanical drawing, even though I flunked the latter, due to teenage attitudinal problems and no corrective factors. Would have taken at least a 2x4, and may have broken it... ;) Bill in OKC William R. Meyers, MSgt, USAF(Ret.) ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Dennis Turk" dennis.turk2x~xxfrontier.com Date: Sat Feb 22, 2014 2:44 pm ((PST)) I have a 5/8 10 tpi Acme left hand tap. Acme thread stock is hard to find in a 5/8 -10. Most outlets like McMaster Carr and others keep standard acme thread stock on hand in right and left hand. Problem is standard acme threaded stock comes 3/8- 12 7/16 -10 1/2 -10 but 5/8 seems to be always 8 pitch. The 5/8 10 lead screws I have had to make my own. Have done several for Standard Modern lathes. Also for a French Lip 4 inch surface grinder I have. Turk ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Dennis Turk" dennis.turk2x~xxfrontier.com dturkcars Date: Sat Feb 22, 2014 2:46 pm ((PST)) Interesting in that the large ring as well as the small ring (Swedish) are not metric threads rather they are inch or imperial threads Glen. I am not sure what the thread profile is though. ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "William R Meyers" wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 3:15 pm ((PST)) I'm considering chopping off a chunk of the better of the two I have. I'd lose about a third of the current travel doing it that way. The worst damage on it is right in the middle of the screw, and more closest to where the collar was supposed to keep the thing from moving back and forth, as it so obviously did. I could flute it on the shaper, and harden it, even if I have to case-harden it. Then make a die, and use that to make a tap, or learn to turn an ACME thread on my lathe. Need to do it anyway, may as well do more than one of them. I've looked for a tap, not had any luck finding one yet. Will probably keep looking in case the money fairy visits again. ;) As you've done this, does it make better sense to use easy-machining stock, or tool stock, for the leadscrews? I'd have to buy 5/8 or a bit larger stock and turn it down anyway, as I don't have anything but Lowes Mystery Metal in that size right now, but have several options for buying a better grade of stock nearby. I do have 24" of 1" 12L14, which would let me reproduce the collar on the current cross-rail leadscrew. Easy machinging sounds like "easy to damage" to me, though. Bill in OKC William R. Meyers, MSgt, USAF(Ret.) ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Charles" xlch58x~xxswbell.net Date: Sat Feb 22, 2014 4:32 pm ((PST)) A lot of old machinery uses a square thread form, since Acme didn't appear til the end of the 19th century (I have several 19th century machines with square threads). You will also see it used on screw jacks well into the twentieth century as it is lower friction. Charles ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sat Feb 22, 2014 7:06 pm ((PST)) "A lot of old machinery uses a square thread form" Yes, but the Lewis shaper came out in the 50's. The acme thread was so obviously superior in almost every way that the square thread was an archaic form in a very short time. The Acme thread was first mentioned in 1895. But it is so obvious to any machinist with any understanding of what he is doing in the tool/metal interface that the slightest taper to the sides makes threading easier that I'm sure it was used long before that. You should feel how square threads and half nuts engage! I'm sure even there that they put a taper at the tops of the minor diameter threads so they can engage a bit easier. Otherwise they have to have a lot of play between the sides of the thread forms, ID to OD, to ease engagement of the halfnuts. Looking back at this conversation I've enjoyed it, but later it occurred to me that the term acme was harder to remember than square, as opposed to V threads. They do look a little squarish. I didn't mean to make a big deal of it. Bill, making a tap out of the same screw can be done, but there are much better ways. Any material with medium carbon can be made into a fine tap for limited use, much better than case hardening IMO. The reason using the same screw is problematic is that you end up either having to make your new screw smaller or wobble the tap around in the hole like a tribesman on a red dirt floor in the third world to get it to make a hole large enough to pass the same sized thread. Also, a hand ground 29 degree boring bar will thread an acme nut, it's much more difficult than a V thread because the shank has to be so small for clearance. You can also buy a nut made of bronze with a LH acme hole reasonably cheaply. http://www.roton.com/mating_components.aspx?family=7160450 Glen ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sat Feb 22, 2014 7:07 pm ((PST)) > So will a ruler, Glen. Just count the number of bumps in an inch, > or a centimeter. Really? Do you think that being a commercial machinist for almost thirty years I may have thought of that? Glen ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 7:50 pm ((PST)) I figured that you'd thought of it, but didn't know that I would or even could. After all, I'm not a machinist. Just a wannabe. ;) And I do have some serious holes in my knowledge of machining. I've been reading about it for about 40 years, but not gotten much practice. That makes it harder to put things together, and make sense of some of what I "know." Lots of book knowledge, not much sense, so to speak. I'm fairly expert in enough other fields to know that I'm very much not in this one. ;) Bill in OKC ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: dkinzerx~xxgmail.com don_kinzer Date: Sat Feb 22, 2014 7:11 pm ((PST)) > Don, how much of that screw-stock do you have left I believe that what I have is the same as the MSC p/n 01206176. It's 5/8-10LH Acme. Their price is $170 for a 6 ft. piece. I have 55 inches left and I'd be willing to sell part of it. How much do you need? Don Kinzer Portland, OR ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 7:51 pm ((PST)) It looks like somewhere between 25 & 30 inches. I'm not at all sure I can afford to buy it. What would you want for about 4-6" of the stuff? I could use that to make a tap, at least, and bootstrap myself up. For me this a hobby, and I'm on a very limited budget at least until (and unless) I could start making some money at it. Seeing how long it's taken to get this far, I'm not holding my breath waiting for it to get profitable for me. ;) Bill in OKC ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Sat Feb 22, 2014 7:59 pm ((PST)) Glen, from what I understand, the Lewis shaper came out in the 20's or 30's, and stopped being produced in the 50's. I know I have pdf's of a 1937 catalog, and one undated as far as I can see, but during or maybe a bit post-WWII. Nothing after that, that I can find, anyway. I also know I'm missing a drawing or two, as they are numbered and lettered, 106 is the shaper overview, showing the main castings, and 106-?, I have 106, 106-B, C, D, E, F, & G, and I expect there should be a 106-A that I don't have, and possibly others. Parts lists, directions, etc. On using a chunk of one of the lead screws, I was thinking that it would at least be close to the size of the tapped holes in the main and cross-rail castings. I've already put a 1/2"id/5/8"od bronze bushing in the left side of the cross-rail to center that leadscrew. I think it being free to flop around had something to do with the leadscrew being buggered up. ;) It also marked the back of the cross-rail slide from flopping about. I think I need to get a dog-point set screw for the collar until I can come up with a better way to do the job. A guy named Ron Shimon refurbed one he got partially completed, and it looks like he put something like my Atlas MF mill has on the table screws at each nd of his cross-rail screw. I will probably try that. After I get the mill going, and learn how they did it. ;) In the mill's IPB they're just called "plates" and they hold the screw in tension from both ends. I think my Lewis needs that, too. Will need longer screws to make that work, too. ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: dkinzerx~xxgmail.com don_kinzer Date: Sun Feb 23, 2014 2:16 am ((PST)) > What would you want for about 4-6" of the stuff? I'd be happy to send you a piece that size. Send me your address. (don at kinzers dot com) Don Kinzer ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Jim S" mrjschmidtx~xxhotmail.com toolingjim Date: Sun Feb 23, 2014 2:17 am ((PST)) > Interesting in that the large ring as well as the small ring (Swedish) > are not metric threads rather they are inch or imperial threads Glen. > I am not sure what the thread profile is though. Just for the record, the Mauser was a metric diameter 55 degree Whitworth thread with 12 thread per inch English pitch. The best guess I have read as to why this is so suggested, that unlike later on, mid/late nineteenth century Germany was not yet an industrial powerhouse. Like all developing countries they purchased their first technology from other countries. The surmise was that they bought their threading machinery from England and used the tooling and pitches the machine was designed for, hence the odd metric/English mix. Oh, and for the fellow on this thread who mentioned that he didn’t have much in the way of good shop gear, I would suggest he check out his local ‘antique mall’. These places sell all sorts of oldish stuff, including tools. Woodworking tools get premium prices, even for junk, but metalworking items are often very inexpensive. I think that is because most sellers and buyers have no idea what they are, so demand is low. This is especially so for measuring tools like vernier calipers, mikes, machinists scales, etc. I purchased a large micrometer in its old wooden box for less than the cost of an empty wooden box for wood chisels sitting on the same shelf. If you find something, ask if it is their best price. Some places give a discount of 10% just for the asking. Jim (Just a guy who likes to build stuff) ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sun Feb 23, 2014 9:03 am ((PST)) Thanks Jim, I knew it was some Mauser design, am I right that the Springfield 03 had square threads? ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Charles" xlch58x~xxswbell.net Date: Sun Feb 23, 2014 10:00 am ((PST)) The Springfield had square threads, but it didn't get them from Mauser, more likely from the Krag, which also used square threads. The 1903 was a considerable departure from the Mauser and many consider it inferior. The early ones certainly were due to faulty heat treating. The Mauser was a metric V thread. Interestingly a lot of them were mated to new barrels in the US using 12 threads per inch V thread on the barrel. It was close enough and metric lathes were not common. There are plenty of other guns out there with square threads like the old Savages. A square thread does not impart the radial stresses in the receiver ring. This is another factor that makes it popular for cast iron screw jacks, and why you might find it used on table elevation screws on shapers even if the cross feed is a trapezoidal form (not every one is an Acme thread, there are a couple of other standards and some wildcats out there). I am pretty sure the Z on my 1892 Milling machine is a plain square thread. Charles ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Charles" xlch58x~xxswbell.net Date: Sun Feb 23, 2014 10:01 am ((PST)) Just read this completely. Interesting Jim. Explains a lot. My info came from Dunlap, who I have found a reliable source, but he may have been thrown off by the angle. I believe there are plenty of Mausers out there with a 60 degree 12TPI barrel. Charles ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Sun Feb 23, 2014 4:47 pm ((PST)) Charles, You are right, there is little "expansion" going on in the nut with a square thread. I had never considered that. You can get away with a lot of thread imprecision when the threads are short, though I think on any high powered rifle I would shoot I'd want precision threads. The US armory was in litigation before and maybe during and after the first world war over the Mauser design, clearly they are a lot more alike than different to most observers. Even if there are differences they would look suspiciously like legal dodges rather than improvements. It seems like such dishonest practices couldn't get past the courts even in an anti Germanic climate. "The War Department had exhaustively studied and dissected several examples of the Spanish Mauser Model 93 rifle captured during the Spanish- American War, and applied some features of the U.S. Krag rifle to a bolt and magazine system derived from the Mauser Model 93, to produce the new U.S. Springfield Rifle, the Model 1903. Despite Springfield Armory's use of a two-piece firing pin and other slight design alterations, the 1903 was in fact a Mauser design, and after that company brought suit, the U.S. government was forced to pay $3,000,000 in royalties to Mauser Werke" (Wikipedia) ------- Was: Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Re: square thrds [Metal_Shapers] Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Mon Feb 24, 2014 6:36 pm ((PST)) FWIW ........when doug king visited me a dozen hrs ago, he brought w/ him from Canada the Brit method of cutting square thrds ......& it worked out WELL when i single pointed a 7/16 X10 square nut for a 1890 prentice bros 15 inch compound . set the compound in line w/ the lathe centerline .... grind the tool bit to a slightly under size bit thread STRAIGHT in till you get full depth take slicing cuts on each side, by advancing the compound & cutting in full depth w/ the xslide ..till then you have a fit ... usually more clearance is necesary than "by the book"....AND by grinding slightly under, a precision size grind is not necessary best wishes doc ------- Was: Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Re: springfield vs mauser actions [Metal_Shapers] Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Mon Feb 24, 2014 6:36 pm ((PST)) FWIW ben near 50 yrs now since i put a 22-250 on a springfield action, but IIRC, the barrel had to be beveled at the rear to provide room for the extractor .. so the rear of the case was not supported as well as in the mauser ...i think the designer was trying to avoid patent infringement. & yes i fitted / chambered more than a few mausers at 12 tpi ....we were aware of the metric thrds, but as you say, most lathes cud not handle metric & there did not seem to be any problem w/ 12TPI. later improvements were a recess in the bolt head fully enclosing the case head. incidentally, in blowup tests that PO Ackly conducted, the Arisaka came out the strongest. when the surplus 98 mausers came into the US so cheaply ($10) after WW2, it was like manna from heaven ....no more wrecking beautiful hi walls & engraved Stevens for an action for a varminter. ------- Re: springfield vs mauser actions Posted by: "Charles" xlch58x~xxswbell.net Date: Mon Feb 24, 2014 7:16 pm ((PST)) The cone or bevel on a Springfield receiver was to facilitate loading individual cartridges directly in the breach. There was a magazine feed stop as well, the theory being that you only used the magazine when in a hurry. The Mauser was designed to be only magazine fed. Probably time to return to Shaper talk. Charles ------- Re: springfield vs mauser actions Posted by: "Glen Linscheid" partsproductionx~xxcenturylink.net Date: Tue Feb 25, 2014 1:11 am ((PST)) Doc, Were Arisaka's made in Japan? I'm sure they were later but originally did Japan buy them from Mauser? I owned a late production type 94 Nambu, crudest pistol I've ever seen, but it worked! I was once wanting a Siamese Mauser to have rechambered for 45-70, they were able to take the specific size of either the .45 bored barrels or the size of the cartridges. In the end I could never stand up to the cost though. Glen ------- Re: springfield vs mauser actions Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Feb 25, 2014 10:59 pm ((PST)) Glen. yes, the Arisaka was japanese manufactured ...in 6.5 MM & a reasonably accurate military rifle .....rough looking but stout ...i originally wrote Jap & then thot that term was no longer politically correct but when i went to add on, i had hit a key somewhere & it was erasing stuff so i just deleted Jap (which was the common term during WW2 & after. i remember well the model 94 Nambu.....it functioned adequately BUT there was a REAL problem ...the gun cud be fired by pressing in on an exposed part on the left side of the action ...i dont know if anyone met his demise from that but i did hear that several were near scared to death. i have not had a siamese mauser to examine, but lack of funds is what started my gunsmithing activities...& led me thru the rear door into machining. i bought my first rifle at age 10 for $1,25,,, a stevens crack shot, missing a firing pin ...i filed one from a nail, not knowing any better nor having any other material ...later made a stock from a blank, checkered & carved it after buying a 20 ga lefever that needed a butt stock ....i made more than a few parts for "liberated " guns frorm WW2 w/ only hacksaw, chisel, & files ...finally got a cheap walker turner drill press w/ a key less chuck, (yeah the type used on the eggbeater hand drill)...using it like a lathe made firing pin work a lot easier, and BETTER...& later spent the $100 rent money for a 6x18 crftsmn..... little by little .....enuf,...sorry, got carried away. best wishes doc ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "Jim S" mrjschmidtx~xxhotmail.com toolingjim Date: Tue Feb 25, 2014 11:01 pm ((PST)) > I believe there are plenty of Mausers out there with a 60 degree > 12TPI barrel. There was a lot of confusion about Mauser barrel threads over the years. America was for many years relatively clueless about the thread systems used outside the US. I once saw an old Machinery’s Handbook from between the wars that had exactly two pages on the metric system, and nothing on metric threads or any other metric standards (tooling, gears, etc.). There are copies of the Mauser factory prints for the barrel thread in two books out there, and they show 12 threads (zwelf gewinde in german) with a 55 degree thread angle. I have them both. That said, many, many barrels have been threaded 12 pitch 60 degree and screwed into Mauser actions to make an accurate shooting rifle. The action cleanup taps sold to the trade are 12 pitch 60 degree taps, as are all the prethreaded barrels I have seen. Confusing, isn’t it? Jim (Just a guy who likes to build stuff) PS I think that we better get back to shapers before the moderator notices us gun nuts (grin). js ------- Re: Bill in OKC has finally (after over 40 years!) gotten his own sh Posted by: "William R Meyers" wmrmeyersx~xxsbcglobal.net oldstudentmsgt Date: Wed Feb 26, 2014 2:32 am ((PST)) Jim, at least one of the moderators IS a gun nut. The reason I've wanted, and finally gotten, and am now refurbing my Lewis is among other things to make gun parts on it. Though I doubt I'll be cutting any 12 pitch threads on it. ;) Bill in OKC ------- NOTE TO FILE: Yes this conversation, originally about repairing a metal shaper got way off topic. Fortunately it included some thread information that may be useful. The firearms stuff may be of interest to some of us. But enough for now. The firearms part went on for several more days and you can read those later messages in the Metal_Shapers Yahoo archives. ------- NOTE TO FILE: Threading ACME (threading a square thread) comes up in a conversation in atlas_craftsman when folks are suggesting making a nut rather than buying a fairly expensive replacement. See the conversation here in the text file "Atlas Parts General" with subject "Re: Carriage Part - Nut [atlas_craftsman]" starting Wed Mar 19, 2014. ------- [atlas618lathe] Have any one in this forum actually cut any "none standard threads w Posted by: migueldeservantesysaavedrax~xxyahoo.com Date: Sun Mar 23, 2014 10:06 am ((PDT)) You know! I think that this thread have actually open a very good door for an extremely important question? How many people in the forum have actually cut threads with this lathe? I mean it, not malice intended! There are literally "Thousands Of Different Operations That Can Be Performed With A Lathe". Because no matter how personal I can actually take the messages from other members. I have an other two lathes, and the largest, is the one that I actually use to cut "none standard threads with! Is My Atlas 12/36 and I use a Quickomatic that I installed my self! so.... Really and seriously please you and I mean it, is there any of the members of this community that have actually used this small lathe to cut "High Precision Threads Internally & Externally With It"? ------- Re: Have any one in this forum actually cut any "none standard threa Posted by: azbrunox~xxyahoo.com azbruno Date: Sun Mar 23, 2014 12:30 pm ((PDT)) I cut threads all the time with my 618. My common thread pitch is 36 TPI and I often do 4 lead threads where I set up the lathe for 9 TPI. I've periodically done 50 TPI when I want .5mm as it's "close enough for gov't work". And if I want .75mm, a 36 TPI setup works well too. These are all done single point on various diameters and I make internal and external to match. I've done standard depth of cuts, but also non- standard, such as when one of the parts may be too thin for a standard cut. Mostly I cut into acrylics, hard rubber (ebonite) and brass. Anything harder gets dicey. I built a crank so I hand crank the lathe for all my threading. This allows me to get right up to shoulders. Generally I take cuts of .002" to .004", but final passes of .0005" or less. Each material behaves differently and it's not always easy to get the smooth operation I require without extra work. I've accumulated many extra change gears as well as gear studs so I can keep a few sets of gears readily available to mount on the lathe quickly. Bruno ------- tap for the 1 x 10 tpi [atlas_craftsman] Posted by: rosslathex~xxyahoo.com Date: Mon Apr 21, 2014 10:48 pm ((PDT)) I made an adapter to run the atlas faceplates on my wood lathe to make wood patterns for casting, then clean up the cast item on the metal lathe by remounting on a faceplate -- so I want more faceplates and cast some but need to do the female thread -- doing the adapter thread -male- was interesting per the very grabby cutting. I would like to tap rather than inside thread but don't see them available. Any reasonable sources for the tap? Jim ------- Re: tap for the 1 x 10 tpi Posted by: "Chris Anderson" zertwizx~xxgmail.com Date: Tue Apr 22, 2014 12:07 am ((PDT)) Why not single point? ------- Re: tap for the 1 x 10 tpi Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Apr 22, 2014 8:41 am ((PDT)) non standard ..one in hi speed taps costly ...more so than stndrd...may not find they are available since spindle probably a V thread & not unified ....singlepoint internal no harder than external, just different ...i have a 1-1/2 x8 tap that is worthless for atlas spindle. wt tool, victor mach exchange, travers, enco ...if you can find a carbon one, it MAY be old enuf to cut a V thrd..single point it .....cheaper & you will be the better for it. best wishes doc ------- Re: tap for the 1 x 10 tpi Posted by: wa5cabx~xxcs.com wa5cab Date: Tue Apr 22, 2014 9:20 am ((PDT)) Jim, Bass Tool and Supply in Houston has 1"-10 listed in their catalog, Taper, Plug or Bottoming. As your faceplates will presumably be threaded through you only need a Taper. According to the catalog page, they are USA made. I would consider $80 to $120 as "reasonable" today, judging by the prices on some 1"-8 taps earlier in the catalog. So the listed price of $32.40 has to be Cheap! :-) I didn't call them to check stock but I've bought special thread taps and dies from them in the past and they almost always had what I wanted in stock. I've also never dealt with them for mail order as they are located less than 2 miles from my house but there is an 800 number at the top of each catalog page. URL direct to the catalog page 398 I found the tap on is: http://www.basstool.com/basscat.html#398/z URL to their home page is: http://www.basstool.com/ Unless you already installed it, you will probably be prompted to install an upgrade to the Adobe Flash Viewer in order to view the catalog. This only takes 2 or 3 minutes. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: tap for the 1 x 10 tpi Posted by: "Jim Ross" j-ro7x~xxcomcast.net Date: Tue Apr 22, 2014 6:27 pm ((PDT)) The tap is a good price and will get one if only just to clean up threads in faceplates and the chucks. Your bass tool seems to beat out me having grizzly 6 miles away in bellingham. I remounted the cast faceplate in the 3 jaw chuck to get the inside end clear of faceplate threads and tried the single point -- lots of flex in the little lathe but did the cut in cast aluminum .. I am not sure how to check the threads for ‘doneness’ without dismounting from the threading alignment —- Sharp point to the top of the threads? Sharp bottom the depth of the cut? thanks Jim ------- Re: tap for the 1 x 10 tpi Posted by: "Chris Anderson" zertwizx~xxgmail.com Date: Tue Apr 22, 2014 7:09 pm ((PDT)) Make a copy of your spindle nose and use that test your threads make sure its very accurate to the spindle. ------- Re: tap for the 1 x 10 tpi Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Apr 22, 2014 9:18 pm ((PDT)) You can also, remove the faceplate AND WHAT IT IS MOUNTED ON, & try it on the thrds ....then if necessary, you can remount on the spindle & continue ...if you take the faceplate off what it is mounted on, you will have to pick up the thread by resetting the xfeed & compound, w/ the 1/2 nuts closed & the b/lash taken out ...a PIA on inside thrds. BUT it can be done, ...i have picked up the thrds on ebay plates /chucks that were fitted to other 11/2 x 8 lathes several times (& a couple times 40- 50 yrs ago on OD thrds when i got lost or things shifted). i wud cut a V thrd ....1x10 = .100 X, 866 =.0866 depth of V thrd .....if cutting in w/ x slide ...if using the compound, increase by by the co sin of 30 deg.....been a long time & my trig may be inaccurate, so it bears checking (IIRC, the atlas handbook has figures for V thrds cut w/ compound) & that shud be somewhere in files. FWIW ...inside & outside spring calipers w/ points filed to abt 59 -60 deg can be used to transfer readings from spindle, & from chucks that fit the spindle to use as an aid to final cut ..they will measure on the pitch diameter 1/2 way down the thrd......they were factory available at one time (POOR BOYS THRD MIC)... the 3 wire system for measuring OD thrds is the most accurate. best wishes doc PS do not know your set up, but the compound can be set differently at times to reduce extension / flex. PPS...if you make a dummy spindle, use wires to mic it DEAD ON ...& probably fit the new work a tad loose if in doubt ....the last one i made worked out well on a faceplate, but a backplate came out too tight & i had to pick up the thrd & increase the depth of cut .......hard to see in there....(& in truth i did not use wires on the dummy ...i fitted it to an existing chuck ...i knew better ...., just short cutting again. ------- Re: tap for the 1 x 10 tpi Posted by: jerdalx~xxsbcglobal.net jtiers Date: Tue Apr 22, 2014 9:36 pm ((PDT)) Good for you. I have always found that the best plan is to just go ahead and attack whatever machine operation it is that you do not want to do. So long as you can develop a reasonable plan for getting it done... I don't advocate blindly rushing in. That gets you experience, and the knowledge that when you have to, you can do whatever it is. Tapping the threads for a faceplate etc isn't the best plan anyhow. Taps rarely go in straight, not as straight as wanted for lathe work, anyhow, no matter what you do. Single pointing is the best plan. If course you clean up the face of the faceplate afterwards, to get it to run true. But the better the threading the less has to come off the face. Oh, yes, I HAVE threaded faceplates and adapters with a tap.... and I wasn't impressed. Never repeated the operation, which was for the little 109 I had many years ago. It worked, though. Jerry ------- Re: tap for the 1 x 10 tpi Posted by: wa5cabx~xxcs.com wa5cab Date: Tue Apr 22, 2014 9:39 pm ((PDT)) Jim, There was a time when Bass Tool & Supply, Roman Sales, Rutland Tool and Supply, Wholesale Tools and WW Grainger were all within a 2 mile radius of my house. Three of the five are now long gone from Houston. Philosophys vary. One school on here would hold that if you CAN (at least theoretically) do (or make) something, you MUST make it. My philosophy is that if you can make it and want to make it or have to make it, make it. If you have better things to do with the time, buy it. You will have to make the register counterbore to an accuracy of about +0.0015/-0.0000. I would just buy the tap and make one face plate to prove up the tap. No, you do not cut until either the root or the crest of the thread is sharp. The root is normally always sharp as soon as you start threading (although the specs do not require it to be quite so). The crest should not be sharp as that would require the root of the mating thread to be sharp (it does not have to be) and would in any case soon enough sustain enough minor damage that it might jam and gaul. The thread tables in Machinery's Handbook will give the proper ID range for the bore before you start threading (you'll have to achieve that before you start either tapping or boring the thread). Then you calculate from the thread tables how many thousandths the cutter needs to move out and as you approach that number, you either use a GO gauge, an ID thread gauge, or you remove the part from the chuck, remove the chuck from the spindle and try the faceplate, using the spindle as the GO gauge. Obviously you have to be able to get the part back in the chuck exactly as it was at the beginning. You can make a GO gauge but it would be worth the labor only if you were going to make several parts using it. And BTW, the threads are not what centers the chuck on the spindle. That is the purpose of the register, which is the short length of unthreaded spindle between the threads and the face of the flange that the chuck or other attachment shoulders up against. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: tap for the 1 x 10 tpi Posted by: "Doc" n8as1x~xxaol.com docn8as Date: Tue Apr 22, 2014 10:15 pm ((PDT)) Robert ...do you know to what thread the atlas crftsmn spindles were cut ???...V thrd? american standard? unified? ...the 1x10 crftsmn wud have been made circa 1958 .....i have fitted plates/chucks to 8 lathes, (2 crftsmn), manufactured from circa 1890 thru 1974 & it seems as if i have always had to cut deeper than what the manual /handbook calls for in order to fit the spindles ....?????? i recently had to pick up the thrds & deepen them on a south bend dog plate needed for a logan 820 lathe, so here is one instance when specs whatever they were, were not equal. best wishes doc ------- Re: tap for the 1 x 10 tpi Posted by: "Steve" skadsmx~xxgmail.com Date: Wed Apr 23, 2014 4:46 am ((PDT)) Machine shop discount supply has the best selection of odd sizes at reasonable prices. http://www.msdiscount.com/ 1"x10 is $33. I got a 1"x16 from them for my milling machine drawbar and it was about a quarter of what anyone else had it. Steve ------- Re: tap for the 1 x 10 tpi Posted by: garybauer46x~xxyahoo.com Date: Wed Apr 23, 2014 6:50 am ((PDT)) Hello All, This has been a great "thread" so to speak. I too have been digging into the 1x10" thread issue for making a faceplate for my little Atlas 618. The 1x10" thread is indeed a special thread. I found taps for it in a couple decade old industrial catalogs at $61 to $64 each. The prices revealled in this thread are the best yet. A larger lathe or tapping machine can run that large 1x10" tap rather squarely into prepared stock but not so precisely as single-point threading on a lathe can do. To obtain a decent single-point thread I have used a smaller tap of the same TPI as the threading tool. It works !!! No need to grind off the non-used points on the tap. I have made some larger faceplates for my old 10x36 Atlas lathe years ago using a 1.5x8 threaded nut trimmed to fit the reference shoulder of the headstock shaft then welded to a thick steel plate. The resulting assemblage is then turned in-place to true it all up. That thread by the way is a standard bolt thread. Very handy. However this 1x10" thread isn't standard in the US... There is a 1x10" BSFW (British Standard Fine Whitworth) nut used on some old Brit sports cars. The nuts are still made here in the US by a company in New York. The BSFW thread has a wee bit sharper V form that the typical 60ş US types... but so what. The register shoulder is what matters. Gary in AZ ------- Re: tap for the 1 x 10 tpi Posted by: "Charles" xlch58x~xxswbell.net Date: Wed Apr 23, 2014 7:00 am ((PDT)) A lot of folks say that, but actually, the chuck centers on the threads unless cocked by uneven cuts on the 90 degree faces of the chuck and spindle. The only way it could center on the register is if it was tapered (like more modern camlock spindles). Charles ------- Re: tap for the 1 x 10 tpi Posted by: jerdalx~xxsbcglobal.net jtiers Date: Wed Apr 23, 2014 4:15 pm ((PDT)) True enough, Charles, but it is generally not worth trying to convince others. The folks who believe in the "register legend" are never convinced by any factual information, the arguments usually get bitter, and are not worth the effort. Better to let them persist, it doesn't hurt me at all. Besides, it looks like Mr Bauer, at least, may mean the *shoulder*, (he said "The register shoulder is what matters.") and that's perfectly correct. The shoulder DOES participate in alignment. The false belief is in the parallel unthreaded portion. It is usually billed as being a sort of "mystical alignment area" that backplates must be carefully and closely fitted to or you will have a worthless, variable, out of true chuck alignment. One or two machines have had unthreaded portions (of different diameter) in front of and behind the threads. Those were helpful in pre-aligning the threads so they could do their conical alignment job. Others have no full diameter area, it is relieved behind the threads. Both work fine. Jerry ------- Re: tap for the 1 x 10 tpi Posted by: wa5cabx~xxcs.com wa5cab Date: Wed Apr 23, 2014 4:28 pm ((PDT)) None of which explains why the tolerance on the unimportant register area of the 10-31T (used all the way from the Timken equipped 10D through the 3996) has a diameter tolerance of +0.0000"/-.0005". Intelligent engineers who have to answer to perhaps less intelligent accountants don't use half a thou tolerances just for the fun of it. Somewhere over the 44 year run of that part someone would have changed the drawing if it weren't important. Robert D. ------- Re: tap for the 1 x 10 tpi Posted by: jerdalx~xxsbcglobal.net jtiers Date: Wed Apr 23, 2014 4:54 pm ((PDT)) Now, let's see the backplate tolerances on the "mating" parts. In my experience, chucks etc are all over the place on that, ranging from 0.060+ clearance, to some considerably smaller amount. Obviously, there will always be some clearance between the chuck/backplate and the cylindrical portion. 2X that clearance is the best alignment the combination can produce as far as TIR. It may be unkind to point out that the OD of that section is identical with the OD of the threads, on which there might well be a close tolerance for any of a number of reasons, although the pitch diameter is also obviously important. The threads were ground from the raw spindle OD which is no doubt what that close tolerance is truly on. I think that a few minutes thought will show that if there IS a tight clearance there, the system will have "fighting tolerances" as the threads and parallel portion each attempt to locate the chuck. Any misalignment will cock it, since the two are at different axial positions, and will lead to a "fighting tolerance" versus the shoulder. It is kinematically redundant. Bad, for any precision fits. If the chuck were held on by a drawbar (no threads on nose), that would be OK, within the slop allowed by anything less than a "wringing" parallel fit between the chuck and the parallel portion. That "wringing fit" would, however, probably quickly wear to a sloppier fit. To prevent that slop, a tapering fit would be better....so taper that section and match it to a taper on the chuck. Voila..... we have essentially invented the modern cam-loc chuck. Jerry ------- confused about cutting 11.5 TPI [atlas_craftsman] Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com Date: Sun May 11, 2014 12:02 pm ((PDT)) I have single pointed a lot of threads with my A/C 12" lathe with QCGB but never 11-1/2 TPI. I just tried to do it and got more like 23 TPI. I checked the sliding gear and it is in the "out" position. That is no surprise since 20 TPI, for example, comes out fine. So what is going on here? Thanks in advance, Rick ------- was: confused about cutting 11.5 TPI: now: guidance to anyone wanti Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com Date: Sun May 11, 2014 4:47 pm ((PDT)) I think I figured this out and have now cut the 11-1/2 TPI correctly. Found nothing to support what I did in the user's book. I set up the QCGB as specified on the plate but only started threading when the threading dial was at the same place for each pass. If I just started at the next tick mark, I would start at two different places and end up with 23 TPI but maybe it was actually 11-1/2 double start. Just thought of that. Rick ------- Re: was: confused about cutting 11.5 TPI: now: guidance to anyone w Posted by: "charles brady" ctb11365x~xxyahoo.com Date: Sun May 11, 2014 5:12 pm ((PDT)) Well that is exactly what happened; the two start thread. Odd pitch threads must be started on the whole numbers on the thread dial; I always start on the 1, odd or even, it just is easier to remember that way. Charlie ------- Re: was: confused about cutting 11.5 TPI: now: guidance to anyone w Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com Date: Sun May 11, 2014 7:41 pm ((PDT)) Charlie, Thanks for confirming my guess. I normally cut 16, 20, 24, and 32 so was oblivious to the problem. Any tick marked worked fine. Just cut 13 TPI and stayed on the same number for each pass. 11-1/2 TPI is both odd and non-integer and it sure needs to be on the same number. Rick ------- Re: was: confused about cutting 11.5 TPI: now: guidance to anyone w Posted by: "David Beierl" dbeierlx~xxattglobal.net Date: Sun May 11, 2014 5:45 pm ((PDT)) For the 12-inch: Even threads - any of the four marks. Odd - any opposite pair. Halves - only the same mark you started with. P. 142 in the Atlas Manual 1988 edition. That page is in the section for 12" change gear lathes, doesn't seem to be in the QCGB section. Yours, David Beierl ------- Re: was: confused about cutting 11.5 TPI: now: guidance to anyone Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com Date: Sun May 11, 2014 7:54 pm ((PDT)) David, My owner's manual is from 1964 and I could not find any mention of the subject. I just updated it with the rules you stated. Thanks! Rick ------- Re: was: confused about cutting 11.5 TPI: now: guidance t... Posted by: wa5cabx~xxcs.com wa5cab Date: Sun May 11, 2014 8:32 pm ((PDT)) The manual which contains the information on use of the threading dial is the Manual of Lathe Operations (MOLO), not the thin 8-1/2x11 unbound white parts and sometimes setup manual that also originally shipped with all Atlas and Atlas-Craftsman lathes. I have 8 or 9 Atlas or Craftsman editions of the MOLO spaced every several years between 1961 and 1988. All of them have three and a fraction pages on use of the threading dial. Depending, at least in my sample, upon whether the front cover says Atlas or says Craftsman, this information will be found on pages 142 through 145 or pages 144 through 147. Robert Downs - Houston wa5cab dot com (Web Store) MVPA 9480 ------- Re: was: confused about cutting 11.5 TPI: now: guidance t... Posted by: "Rick - yahoo" rgsparber.yax~xxgmail.com Date: Sun May 11, 2014 8:43 pm ((PDT)) Ah, now I see it! "Rules for using the threading dial". I've added a few footnotes so I don't miss it again. Thanks, Rick ------- 27 tpi Threading question [myfordlathes] Posted by: "Ken Strauss" ken.straussx~xxgmail.com Date: Wed May 14, 2014 9:52 am ((PDT)) I need to cut some 27 tpi (~0.9407mm) threads on my S7 with QC gearbox. The gearbox gives easy setup for 26 and 28 tpi; I can’t find 27 in the Myford instruction sheet. What do I do? If you are curious, 5/8-27 is apparently “standard” for microphone stands in North America. ------- Re: 27 tpi Threading question Posted by: "mark Dean" markdean61x~xxmsn.com Date: Wed May 14, 2014 10:01 am ((PDT)) 16x1 mm thread seems fairly common for tubing in the uk, it is very close to 5/8x27, the threads might be interchangeable on short lengths, it might be worth a try!! ------- Re: 27 tpi Threading question Posted by: "Adrian Nicolson" adrian_nicolsonx~xxyahoo.com Date: Wed May 14, 2014 10:33 am ((PDT)) Hi Ken, Take the 24 tooth driver off...below the tumble reverse, and replace with a 34 tooth gear (you will have to adjust clearances...but should have plenty adjustment on the banjo). Then set the the gearbox to "cut" 38 TPI. This will then produce a pitch of 0.947mm (to give a pitch error of just over 6 micron). This was taken from the charts produced by Brian Wood on the Model Engineer web-site and as per his articles and charts in MEW 212 and MEW213. I am sure that the actual Charts (produced by Brian Wood) are available for download from the ME Forum web-site. His article expands on the knowledge that by replacing the 24 tooth driver gear with either a 33 or 34 tooth gear...you can cut quite a wide range of metric (and other) pitches. His Charts lay out gears to use...and gearbox "position" for a wide range of Metric, BA, DP Pitches, Holtzapffel thread pitches, etc. Regards, Adrian ------- Re: 27 tpi Threading question Posted by: "Ken Strauss" ken.straussx~xxgmail.com Date: Wed May 14, 2014 10:39 am ((PDT)) Thanks, that is exactly what I was looking for! I knew that I had seen it somewhere but was having a senior moment. ------- Re: 27 tpi Threading question Posted by: "Adrian Nicolson" adrian_nicolsonx~xxyahoo.com Date: Wed May 14, 2014 11:07 am ((PDT)) Hi Ken, Here is the link to the forum page where you download the pdf of the Charts http://www.model-engineer.co.uk/forums/postings.asp?th=94391 Regards, Adrian PS I have just noticed "Table 4 Imperial pitches beyond the normal gearbox range" on one of Brian Wood's Chart Pages... It says that if you used a 32 tooth Mandrel Gear and set the gearbox to "cut" 36 TPI...the then pitch achieved would be 27 TPI. So either way...you have a solution. The reason I gave you the "solution" using the 34 tooth gear...is that the 33 and 34 tooth gears would be the most "useful"...in allowing you to cut "other pitches" as laid out in Brian's Charts. ------- Re: 27 tpi Threading question Posted by: "Ken Strauss" ken.straussx~xxgmail.com Date: Wed May 14, 2014 11:56 am ((PDT)) My joy was short lived! I neglected to mention that my Myford has a North American gear box so I get 11.5/23/46 tpi and lose the 9.5/19/38 tpi of the standard gear box. And I have 28T, 30T, 34T and 35T gears but not a 32T nor a 25T gear (25T + 28tpi would give 26.88tpi). It looks like my best choice using available gears is a 28T + 32tpi to get 27.43tpi. It was good while it lasted! ------- Advice on buying a tap [atlas_craftsman] Posted by: brogers9941x~xxsbcglobal.net Date: Mon May 26, 2014 1:48 pm ((PDT)) I would like to ask for advice on buying some taps (#8-32, 10-32, and 1/4-20). I realize that this is slightly off topic, but it is somewhat related to using my atlas 12 x 36 lathe on projects. General: I'm a hobbyist and occasionally need to tap a project. I have recently been using my drill press to ensure alignment when I'm hand- tapping and to minimize breaking taps. My current tap set is cheap and I notice that when tapping 6061 aluminum that I get a bunch of displaced material ABOVE the tapped hole. I presume that this is the result of a dull tap but perhaps some displacement is normal? I tried hand sharpening the tap with some minor improvement. 1. Brand names - In the MSC catalog I see names like Cleveland, OSG, Interstate, Hertel, etc. Are there some to avoid and some that have higher end-user value than others? The number of manufacturers has me confused. 2. Finish - I hand tap aluminum (6061 and home-cast 356 or "wheelium") as well as 1018 (and occasionally 12L14) steel. I see that some are HSS (shiny), some black oxide and some TIN or TiCN. I'm wondering how much difference that makes. 3. Shape - I generally do through-hole tapping and avoid blind holes. So I assume that a 3-5 thread chamfer or a tapered chamfer would work fine. I also see some taps with a spiral point and a spiral flute. Are these for machine tapping or do they also work well for hand-tapping? With the spiral point or spiral flute, can I skip backing out the tap to clear chips every turn or two? Bruce ------- Re: Advice on buying a tap Posted by: "brokenwrench1 ." brokenwrenchx~xxgmail.com Date: Mon May 26, 2014 2:00 pm ((PDT)) When tapping aluminium i deburr the hole to be tapped and use a 60 degree counter sink bit or a larger drill bit to make a small counter sink. I find in some cases during the tapping process aluminium will push roll form the metal instead of cutting the threads. A high speed gun tap i find works better for me. Another trick i used was using the 3 tap method. The starting tap the form tap and the bottoming tap if i want precise threads. I also consult the machinery handbook for alternate drill sizes for the class fit i want for thread root clearance on different materials. Robert Halbrook ------- Re: Advice on buying a tap Posted by: "Tooldoc" tooldocx~xxcheqnet.net davidhallsten Date: Mon May 26, 2014 2:40 pm ((PDT)) I just did a group buy for 16 taps with 32 stub drills. Do i need to do another one? They were $132.25. Started with 4-40 and went thru 5/16. I should have added these are very high quality USA made taps and Stub drills. Spiral fluted or gun taps, they screw the swarf out, that's what this group buy was. I need ten more interested guys to do it again. ------- Re: Advice on buying a tap Posted by: "JACK SIMS" jack-br549x~xxatt.net Date: Mon May 26, 2014 2:55 pm ((PDT)) Stick with Cleveland or other USA made taps, stat away from the cheaper ones. Do back out and clear chips with any tap, my opinion only, have fun. And be sure to put a good chamfer on the hole before you try to do your tapping. Jack Sims Carrollton, Texas ------- Re: Advice on buying a tap Posted by: billg1277x~xxgmail.com bg7701xj Date: Mon May 26, 2014 7:53 pm ((PDT)) Good advice already said... If you're looking for taps that you can buy at a store try Fastenal. Some of the best taps I've used. Now, these are made in china, but they blow away snap-on, vermont and Irwin. If you're doing some aluminum and steel I would advise to keep taps strictly set aside for aluminum only. They need to stay as sharp as possible especially with the small stuff. Should always chamfer the hole before tapping. Easier starting tap and bolt plus looks more professional. I use 90 degree countersink bits. Spiral flute taps are great and really all that should be used for blind holes but smaller sizes seem weaker than straight flute. Break chip often on deep holes. There's plenty of choices for taps with different coatings for different uses or materials. Generally I just buy the plain or shiny to save a little money. Honestly I don't know if any coating really helps for aluminum. ------- Re: Advice on buying a tap Posted by: "brokenwrench1 ." brokenwrenchx~xxgmail.com Date: Mon May 26, 2014 8:37 pm ((PDT)) I like to go to a small town with an old hardware store they generally had a display of bulk drills taps and dies in a counter top case either by irwin , ace, hanson or cleveland. I have had good luck with the hanson and ace brands made in usa for a long time. They furnished to the tool trucks for years. ------- Re: Advice on buying a tap Posted by: "Kevin Gibson" k3030aix~xxyahoo.com Date: Mon May 26, 2014 8:39 pm ((PDT)) I thought Irwin made Snap On and Matco taps. I have a set of Matco's and both my std and metric are in plastic cases identical to cases that Irwin's are available in. Kevin ------- Re: Advice on buying a tap Posted by: "Carvel Webb" carvelwx~xxabsamail.co.za Date: Tue May 27, 2014 12:20 am ((PDT)) Bruce, After many years of mixed experiences (and emotions!) I invested in a set of spiral point (machine) taps for general use. They work perfectly as hand taps . The only exception is of course if you need to tap a blind hole. Make sure you get HSS, not carbon, and in most cases one can tap through without backing off. Apart from chamfering, the key to tapping small holes in aluminium in my experience is to use a cutting fluid designed for aluminium – “Tap Matic” in this part of the world. One can normally “feel” if the tap is cutting comfortably, and it is only necessary to back off if the going gets tough to avoid breakage. It is essential to get the tap perpendicular to the work. If not convenient to start the tap with your drill press, then take a short piece of squared off bar stock and drill a clearance hole through it and use that as a guide for the tap if the piece you are tapping has a flat surface. Alternatively use your lathe to drill a hole for a guide rod in the back of your tap wrench, and hold the guide rod in the drill press while turning the tap wrench by hand. Regards, Carvel ------- Re: Advice on buying a tap Posted by: "brokenwrench1 ." brokenwrenchx~xxgmail.com Date: Tue May 27, 2014 1:28 am ((PDT)) this style is what i use as starter taps; the ones i like are cobalt http://www.ebay.com/itm/4-NEW-5-16-18-HS-GH3-HAND-GUN-TAPS-DIFFERENT-BR ANDS-/141297203964?pt=LH_DefaultDomain_0&hash=item20e5f83afc ------- Re: Advice on buying a tap Posted by: "L. Garlinghouse" lhghousex~xxsuddenlink.net Date: Tue May 27, 2014 8:22 am ((PDT)) Good question -- My recent experience [last 6 months]: I've bought some Hanson taps at my local ACE hardware and both of them cut small in aluminulm and steel and had to be chased with a name brand US made tap. Several years ago I bought sets of SAE and METRIC tap and dies from Harbor Freight for a very reasonable price figuring they might be really good, but in any case they would at least be good for chasing existing threads. NOT!!! I have been able to use the cheapo holders I got in the sets, but have not really discovered what to do with the other contents. Finally, sometimes the proper lubricant can make an unbelievable difference in a good way [I guess that is what "proper" means.]. "Tap Magic" is one that is available and well regaraded -- especially the one for aluminum. Kerosene works OK on aluminum too and if you are lazy, or pressed for convenience, WD-40. Sulphur based oil [aka "thread cutting oil" at ACE and elsewhere] is good for steel and ATF is better than nothing. Before this becomes a cutting oil tangent that changes into a zombie thread, look up what Machinery Handbook says and the archives on this and other relevant groups. Later, L.H. in the Southern Ozarks ------- Re: Advice on buying a tap Posted by: "Kevin Gibson" k3030aix~xxyahoo.com Date: Tue May 27, 2014 9:22 am ((PDT)) I have yet to actually tap anything with the cheapie HF tap and die set. It's rare I need taps and dies so I picked up a set just to have around. Worthless! Stick with Irwin taps, I've had very good luck with them. Kevin ------- Re: Advice on buying a tap Posted by: "Richard Marchi" rfmarchix~xxaol.com Date: Tue May 27, 2014 6:57 pm ((PDT)) There are traditionally three tap styles: taper, plug and bottoming. In high production, taper taps were used to start a hole and bottoming tap to finish a blind hole. Plug taps were kind of an in-between option. Of course, spiral fluted taps have become the choice for high production, these days. tough to get old. Richard Marchi 600 Water Street, SW NBU8-2 Gangplank Marina Slip H-22 Washington, DC 20024 ------- Another problem encountered; buggered up spindle threads...[atlas618lathe] Posted by: curtis.normanx~xxcomcast.net crackerfactory03 Date: Tue Jan 6, 2015 3:44 pm ((PST)) I have another problem that you guys might be able to help me with. When I tried to remove the spindle collar at the rear of the Atlas 618 lathe that I just recently acquired, I had a very hard time unscrewing it from the spindle. It came off, but then I discovered why the collar was so stiff coming off- the little lead ball that was supposed to be under the setscrew was missing, and apparently has been missing from the spindle for a long time. Of course, the previous owner had tightened that set screw down hard against the spindle threads there and those threads are deformed. When I go to put the headstock back together again I would either have to use a wrench to tighten the collar back onto the spindle (which I am not going to do) or somehow attempt to renew the threads at least to the degree that the spindle collar (part M6-32) will screw on more freely. That end of the spindle measures .749", I think (I wrote it down while in the basement, but forgot to bring the paper upstairs to the computer with me). I am not sure where I would get a die that size to run onto those threads and reshape them. Any ideas how best to proceed with this problem? Since I got the collar off (with a lot of torque applied with a wrench)? I am pretty sure I could get it back on but really do not want to use the Neanderthal method again. Another consideration is the Timken bearings- they are filthy with black oil and I have even found some black gritty grease inside the bearing housing. I do not know how they could even get that dirty excepting that the person who owned this machine prior to me seemed to be in love with grease. There is thick black gritty grease all over the inside of the headstock, on and under the bed- everywhere. So I am thinking; time for new bearings, perhaps? Thanks in advance for your input, fellows! Regards, Curtis ------- Re: Another problem encountered; buggered up spindle threads... Posted by: rgarzottox~xxcomcast.net rgarzotto Date: Tue Jan 6, 2015 5:24 pm ((PST)) The threads are 3/4-16 file them a bit then lap the nut back on. Clean threads well after lapping. Rich Chicago Il ------- Re: Another problem encountered; buggered up spindle threads... Posted by: "The Wiesers" wiesersex~xxverizon.net isaacsdad1 Date: Tue Jan 6, 2015 7:05 pm ((PST)) Get a thread file! Bought two (standard & metric) years ago from Snap-On man, have SAVED THE DAY numerous times! Keep them well oiled and wrapped in a shop towel for the time when needed most! My 618 was same as yours, past owner buggered the main spindle all to heck! I used the thread file for the threads & Arkansas stones to smooth the divots on the spindle from the set screws! Good Luck, Steve ------- Re: Another problem encountered; buggered up spindle threads... Posted by: burkheimerx~xxverizon.net ar1911 Date: Tue Jan 6, 2015 8:15 pm ((PST)) Get a thread file, be sure it has a 16 TPI face. I would also buy a new nut from Clausing, and possibly the correct spanner wrench for it. ------- Re: Another problem encountered; buggered up spindle threads... Posted by: wa5cabx~xxcs.com wa5cab Date: Tue Jan 6, 2015 11:01 pm ((PST)) Curtis, I whoeheartedly agree with Steve. Invest in a good US made thread file set for Inch threads. The metric one is optional. There should be two files in the inch set. The files are about 1/2" square, and have 4 thread pitches on each end. Total of 16 pitches. They should come with a plastic protector over each end. Only remove the one on the end of the file you are using. As soon as you are done using one of them, always replace the protector. I bought my set around 1975. Over the years, they have saved many projects. The set won't be cheap but may be cheaper than the die nut that you would likely only ever use once. To use, secure the spindle with the bad spot at about 12:00. Lay the correct pitch onto the threads slightly before the bad spot (say around 12:30). Push the file with a rocking motion to about the same distance on the far side of the bad spot (maybe 11:30), keeping the file on a tangent as it goes up and over. Lift file, back up and repeat four or five times. Inspect the threads. Ignore the damaged thread crests, as there is nothing you can do about them, and they won't hurt anything. Try the collar. If it is still tight over the damage, run another half dozen strokes and check again. Robert Downs - Houston ------- Re: Another problem encountered; buggered up spindle threads... Posted by: "Jim Ross" j-ro7x~xxcomcast.net Date: Tue Jan 6, 2015 8:24 pm ((PST)) Lapping a nut? I get a picture of this but wonder about the details. I have an outboard faceplate that does not fit the outboard spindle and took two large pipe wrenches to remove. It is LH and 1 1/8” 8 tpi for an Oliver lathe so I don’t go to the hardare store. I cleaned the spindle with a triangle file at low speed –vfd— but the faceplate is another matter...aluminum about 8" dia -- will lapping of threads give me a smoothfitting of the faceplate? how?? jim ------- Re: Another problem encountered; buggered up spindle threads... Posted by: "Robert Paine" rpainex~xxvom.com rpaine Date: Tue Jan 6, 2015 11:08 pm ((PST)) Jim, I would not try lapping aluminum. The aluminum is soft enough that the lapping compound will likely become imbedded in the aluminum and remain there to cause excess friction and a cutting action any time you unscrew the face plate. The lapping compound will be cutting the steel rather than the aluminum. RPaine ------- Re: Another problem encountered; buggered up spindle threads... Posted by: youngberg.brianx~xxyahoo.com youngberg.brian Date: Wed Jan 7, 2015 5:32 am ((PST)) After you refresh the threads on your spindle, be sure to install a lead buffer in the collar’s set screw hole. I found that an 1/8” slug of 1/8” diameter 50/50 solid core solder worked perfectly. BRY ------- Re: Another problem encountered; buggered up spindle threads... Posted by: curtis.normanx~xxcomcast.net crackerfactory03 Date: Wed Jan 7, 2015 9:29 am ((PST)) Thanks Brian, good suggestion there- I hadn't thought of solder for this application. Regards, Curtis ------- Re: Another problem encountered; buggered up spindle thre... Posted by: "Dan Dobbs" k.dandobbsx~xxatt.net Date: Wed Jan 7, 2015 7:57 pm ((PST)) Paste smootheth and it taketh away (sometimes too much where you don't want it). Look for another way. This would be the line of last resort. ------- Grinding internal threading tools [myfordlathes] Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac Date: Tue Mar 3, 2015 9:30 pm ((PST)) G'day all, Cut my first internal thread last night. Put an M18x1.5 into a piece of 1/2" galv water pipe. I used the tool inverted and at the back of the workpiece, which seemed more natural for me as I could wind the top slide on like I do when threading externally. I ground up a tool from a piece of 5/16" HSS. Reducing the neck was a bit of a task on the grinder, but grinding an accurate 60 deg tip was far worse. I have a 8" grinder with an 80 grit grey wheel for roughing, and a 6" grinder with a pair of 200 grit white wheels for finishing. One of those I reserve for jobs where I need a sharp corner on the wheel and that is what I used to cut the internal face. I then honed it up with my new favourite tool (ezy-lap handheld fine diamond stone). The M18 thread is to screw one of my dremel style tools into so I can make a honing jig with it and some small diamond wheels. Hopefully that will help me make a better job of it next time. I realize now that I could have used my boring bar and just ground up a 3/16" bit with a 60 degree tip on it, but at the time a stand alone tool felt like a better idea. I certainly need the practice grinding anyway. The finish on the thread was quite torn and I figure that is because the grinding was pretty ordinary and there was zero rake on the top of the tool. Having said that, the water pipe is pretty nasty steel to turn anyway. I have a rudimentary adjustable grinder rest with a protractor and slide, but nothing fancy. Is there a better way to make an internal threading tool? Regards, Brad ------- Re: Grinding internal threading tools Posted by: "Ian Newman" ian_newx~xxyahoo.com ian_new Date: Tue Mar 3, 2015 10:11 pm ((PST)) Hi Brad, Internal threading is fun isn't it! The only thing I would add to your method is that, if possible, cut the thread with the lathe in reverse and the tool the right way up in the toolpost, cutting on the far side of the thread (as you did). This allows you to see what is happening (cutting on the far side) but the tool starts at the bottom of the thread and moves outwards, so you do not have nervous moments deciding when to stop the feed to avoid bottoming the tool on the bottom of the threaded section. This method is not possible if you have a screw on chuck. The other observation is that it is worth investing lots of time getting the tool profile correct -- you will only ever do this once as the tool will get almost no use (unless you cut vast numbers of internal threads) and so only ever needs a little honing to keep it in shape. All the best, Ian ------- Re: Grinding internal threading tools Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac Date: Tue Mar 3, 2015 10:59 pm ((PST)) Actually, I'm finding threading in general to be an absolute lark. More so once I discovered that for the sort of threads I turn, the early myford metric approximations are actually adequate to do a reasonable job and I don't need to buy a set of 21T gears to get into it. > The only thing I would add to your method is that, if possible, cut the > thread with the lathe in reverse and the tool the right way up in the > toolpost, cutting on the far side of the thread (as you did). And so when I ground the tool initially this is precisely what I had intended to do. Once I had a tool that looked spot on I remembered... > This method is not possible if you have a screw on chuck. ... and thus I threw the tool away and started again (ML7). As a legacy of some of the tiny electronics I fiddle with, I have a small (sub 6mm) borescope head mounted on a mag-base and hooked up to a 17" monitor. I use that as a permanent set of remote eyes for when I can't see what I'd like to see. It has proved extremely useful on the lathe for things like this. > The other observation is that it is worth investing lots of time getting > the tool profile correct I figure this is the case with a lot of my HSS tools really. I've started working on finishing tools that are ground and honed to as close to perfection as my shaky hands allow. Then I just hit the grinder with roughing tools to do the heavy lifting. I've found that doing this means all the finishing tools need is an occasional wipe on the stone to keep them razor sharp and making fine steel wool swarf. I spent a great deal of time making a very nice external threading bit, and the finish it produces is lovely. I think I was in a rush, and I was frustrated at having wasted the first internal tool by grinding it upside down, so the profile and finish was not as nice as it could have been. I've got plenty more 1/2" pipe, so I might have another crack at the tool and try it again. I find time at the lathe quite cathartic and I've got a nasty perfectionist streak, so I don't mind doing the same job 5 or 6 times as long as each time it sees incremental improvement. Regards, Brad ------- Re: Grinding internal threading tools Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Wed Mar 4, 2015 5:41 am ((PST)) Hi Brad, You say the finish on your thread was quite rough. Were you feeding the tool straight in at right angles? Setting the top slide over to 25 degrees allows you to do virtually all the cutting on one side of the tool as you feed it in and reduces the likelihood of tearing bits out of the workpiece. Apologies, grandmother, eggs, etc. Regards, Alan ------- Re: Grinding internal threading tools Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac Date: Wed Mar 4, 2015 6:13 am ((PST)) No, no. All suggestions warmly welcomed. It's a poor day when you don't learn anything. I had the top slide over at ~29.5 degrees. I found that works nicely for external threading, and figured it'd do the same for the internal. I set the cross slide to a nice round number, and use that to retract the tool while running the lathe backwards to return to the start, and then put it back *exactly* where it was. I do all feeding with the top slide. I got the 20x magnifier out tonight and had a look at the threading tool. While the 60 degree angle is spot on, the relief angles are wrong and the honing process has introduced more facets than were there off the grinder. So ultimately it's just an ugly little tool which tears up the steel rather than peels it off nicely. I did get "better" results using my bracket for the shop vacuum nozzle to evacuate the chips as they were produced. Kept the lathe cleaner too. I'll sit down on the weekend and have another go at grinding one up from scratch. I just need to pick up some more 1/4" tool blanks as I'm out. I've found what appears to be a source of O1 tool steel locally (I think it's known as Silver steel in the upper hemisphere), so I might buy a couple of meters of that to play with. All indications are that it's a pleasure to turn and hardens up nicely. ------- Re: Grinding internal threading tools Posted by: "Andrew Moyes" admx~xxamoyes.fsbusiness.co.uk moyes_a Date: Wed Mar 4, 2015 6:11 am ((PST)) When using this method, a trap for the unwary is that the topslide should be rotated with the feedscrew handle to the right for external threads and left for internal threads, both assuming a front mounted tool. And the converse for an inverted tool at the back. Otherwise the backlash in the leadscrew will give a rough thread. It's perhaps obvious when explained but caught me out for a while -- I couldn't understand why I was getting lousy internal threads. Andrew M ------- Re: Grinding internal threading tools Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Wed Mar 4, 2015 6:31 am ((PST)) Andrew: Am I right in thinking that what you are saying is rotate it 25 degrees anti-clockwise to cut an external thread and 155 degrees anti-clockwise for an internal thread (assuming your topslide will go round that far). Any backlash is always in the same direction then. Alan ------- Re: Grinding internal threading tools Posted by: "Andrew Moyes" admx~xxamoyes.fsbusiness.co.uk moyes_a Date: Wed Mar 4, 2015 7:32 am ((PST)) Alan: Rotate the topslide 25 degrees anti-clockwise for an external thread (turn topslide feedscrew clockwise to apply cut) and 25 degrees clockwise for an internal thread (turn topslide feedscrew anti-clockwise to advance cut). In both cases, you're advancing the cut into the left hand flank of the thread being cut, so the reaction is always pushing the saddle to the right against the leadscrew. Andrew M ------- Re: Grinding internal threading tools Posted by: "Robert Mitchell" rmm200x~xxyahoo.com rmm200 Date: Wed Mar 4, 2015 7:58 am ((PST)) Silver steel is a British term. O1 would not be my choice to play around with -- unless you need a hardened finished product. If you are buying a couple of meters, your budget is bigger than mine. Try for some leaded steel -- that is a pleasure to turn. [and in a later message] I think I misunderstood -- O1 is excellent to make cutting tools from. Leaded steel like 12L14 is great to make threads in. ------- Re: Grinding internal threading tools Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac Date: Thu Mar 5, 2015 12:24 am ((PST)) Yes, that is what I meant. The place I found to source O1 only does it in 1000mm lengths, so I figured a length of 8mm and a length of 14mm would probably do me for a *long* time. I know it's not going to be cheap, but then I'm already paying $15 for 3 bits of crap Chinese 1/4" HSS and seem to be going through it like I'm eating it. I've been looking at some leaded steel to play with, but a lot of the things I've been making lately also need a bit of welding and I believe TIG and leaded steel are pretty incompatible. To be honest I've been spending a lot of time refining my tool edges to get a nice finish in whatever offcut crap steel I can lay my hands on. ------- Re: Grinding internal threading tools Posted by: "Martin" dumptongeex~xxhotmail.com dumptongee Date: Thu Mar 5, 2015 12:30 am ((PST)) To set up for cutting internal threads, take a look at https://www.youtube.com/watch?v=olC9xyHheDU AND all mrpete222's other videos and all the other Youtube videos on this subject, And FREE downloadable machinists books. Google it. Martin ------- Re: Grinding internal threading tools Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac Date: Thu Mar 5, 2015 1:06 am ((PST)) G'day Martin, I had already watched that video (and many others) however as I said in my original post I wanted some advice on grinding an internal threading tool, not grinding a tip to use in a boring bar. I have spent many hours in front of google and read most of the freely available downloadable machinists books. I turned to the list because as a source of information this was inadequate, with most concentrating on using a tip in a boring bar. My boring bar won't fit in some of the holes I'm threading, and thus I wanted to learn how to properly grind a complete tool from a stock bit of HSS. As I stated in my original e-mail, I've done it and the results were barely acceptable so I was after some advice on how to do it better. If you have some definitive sources for me to watch or read, I'd be most grateful, but I've already watched a _lot_ of mrpete222's stuff and read a lot of books. Almost none talk of how to approach this particular problem suggesting that if the hole is too small for a boring bar then one best use a tap. I find this particular list gives *valuable* advice based on real experience with small lathes, that is often not available or referenced elsewhere. If you believe I'm out of line asking experienced hobbyists and machinists for advice then feel free to ignore my question. Telling me to "google it" is a *wee bit* patronising and appears to imply I've done none of that before asking for additional advice from the list. I've actually had some incredibly helpful replies from people with relevant experience to share. Regards, Brad ------- Re: Grinding internal threading tools Posted by: "Cliff Coggin" clifford.cogginx~xxvirgin.net cliffcoggin Date: Thu Mar 5, 2015 1:26 am ((PST)) Please keep asking Brad as I get some useful advice from the replies. You’ll just have to accept the fact that many people don’t bother to read the questions fully in their eagerness to respond and get the thrill of seeing their names “on the internet”. And that’s particularly true of the HSS/carbide tools debate when the world and his uncle want to display their preferences. ------- Re: Grinding internal threading tools Posted by: "Martin" dumptongeex~xxhotmail.com dumptongee Date: Thu Mar 5, 2015 1:44 am ((PST)) I am sorry you have taken offence at my attempt to help you, this was the last thing I expected ,but having seen the various questions regarding turning the topslide 25 degs etc, it appeared to me that you would benefit from my suggestions....obviously my mistake....perhaps I have misunderstood those posts. Never mind, I shan't take the risk of patronising you with any further suggestions, especially as the other members of this group probably have much more experience than I have. I was not setting myself up as some sort of know-it-all Guru, I am someone who has benefited from asking questions from this group in the past, & I definitely don't know it all......does anybody? Anyway, how was I supposed to know what you've read.....or what you've seen....or what you know? Martin ------- Re: Grinding internal threading tools Posted by: "Brad Campbell" lists2009x~xxfnarfbargle.com yeldarb_llebpmac Date: Thu Mar 5, 2015 2:44 am ((PST)) G'day Martin, I unreservedly apologize for my outburst. It was both rude and un-called for. I'd make an excuse to do with the sort of day I've had, but that'd be trying to absolve myself of the responsibility for my rudeness. I'm glad my mother does not subscribe to the list. Regards, Brad ------- Re: Grinding internal threading tools Posted by: "Martin" dumptongeex~xxhotmail.com dumptongee Date: Thu Mar 5, 2015 3:15 am ((PST)) OK Brad, all is forgiven. Cheers, Martin ------- Re: Grinding internal threading tools Posted by: "Tony Jeffree" tonyx~xxjeffree.co.uk tonyjeffree Date: Thu Mar 5, 2015 2:10 am ((PST)) Brad -- If the primary problem is getting the right tooth form, then one possibility is to start with a tap of the right pitch (but no greater diameter than the thread you want to cut), and modify that to suit -- grind off two of the 3 flutes, etc. Leaving it as a multi-tooth cutter may help with the quality of finish too. Regards, Tony ------- Re: Grinding internal threading tools Posted by: anthrhodesx~xxaol.com anthrhodes Date: Thu Mar 5, 2015 9:55 pm ((PST)) Brad, One thing I've seen suggested is to take a tap for the pitch desired and grind off all but one tooth of the tap. You can grind off additional material from the shank to be more comfortable with the clearances. It becomes a dedicated boring tool for cutting a particular inside thread. Should be useable for the same ID and pitch as the original application of the tap and probably for larger IDs for the same pitch. This is not a perfect solution, ability to grind a tool for a particular application is highly desirable. However, for an immediate solution for a particular job it's worth considering. Anthony Berkeley, Calif. ------- Re: Grinding internal threading tools Posted by: "Paul Kennedy" clankennedy2004x~xxyahoo.co.uk clankennedy2004 Date: Sun Mar 8, 2015 7:00 am ((PDT)) My two cents worth referring to cutting a thread in an internal diameter. If the hole is too small to fit even a small boring bar then you should be using a tap. In my experience, depending on the material to be tapped of course, grinding up a tool specifically for a specific hole diameter is more hassle than it's worth. I've tried it, and due to the material's hardness that I was attempting to thread, the boring bar deflected due to its lack of rigidity as it had been ground up to fit the hole. I ended up tapping the thread instead. Of course if it had been brass or a leaded steel then it might have worked :/ Using a tap is just easier, quicker and gives better results for small diameter holes in my opinion. ------- Threading [Sherline] Posted by: nbutterfield34x~xxyahoo.com nbutterfield34 Date: Fri Apr 24, 2015 9:26 am ((PDT)) As a new member and a new Sherline lathe user I would like info on how you fellows are threading on the lathe, both with a die and a tap? Not single point cutting but using taps and dies. Thanks, N. ------- Re: Threading Posted by: jowhowhox~xxyahoo.com jowhowho Date: Fri Apr 24, 2015 1:23 pm ((PDT)) I don't use spindle power for tap and die threading. I use the Sherlines to get good alignment, then finish the thread using a handle. I also do this in my drill press -- no power. Or I CNC single point with a stepper on the spindle. I never use the threading attachment. Justin ------- Re: Threading Posted by: nbutterfield34x~xxyahoo.com nbutterfield34 Date: Fri Apr 24, 2015 4:44 pm ((PDT)) Thanks Justin. In using your Sherline to get good alignment, what typical sizes and what material are you using? Do you go over 1/4" tap or die for example? Are you using steel or aluminum, plastics, and other soft materials? I'm trying to get a sense of what others are doing on their Sherline. I have larger machines but attempting to set up for smaller model work with my new Sherline which will entail using steel, aluminum and even some plastic. I do not have any CNC and will need to make threaded multiples in small quantities, both internal and external threads. Looks to be an awkward process on the Sherline. That is why I was questioning how others are doing their threading. I've seen very little discussion concerning threading in this Yahoo Group which surprises me as in my model work I do a lot of threading. How do you fellows cut your #0-80's and #2-56's quickly? Neil ------- Re: Threading Posted by: "procter" procterx~xxihug.co.nz kwstse Date: Fri Apr 24, 2015 9:52 pm ((PDT)) The Sherline isn't intended for powered thread cutting. Thread cutting with a tap or die is easiest - the lathe effectively aligns the cutter and material. The threading attachment works ok and can produce non-standard diameter threads - eg camera lens threads. Any material from plastic to machinable steel can be threaded. I haven't tried stainless. Personally I buy standard size bolts and nuts where they are available as there is a certain amount of effort involved - I have plenty of tasks to take up my hobby time :-/ For a long threaded rod that isn't available at the hardware shop the Sherline does a good job. Regards, Greg.P. ------- Re: Threading Posted by: "Tom & Judy Bank" trbank1x~xxverizon.net eimcr28 Date: Sat Apr 25, 2015 8:07 am ((PDT)) Neil, Two photos of the way I do my tap and die threading on the Sherline lathe are at: https://groups.yahoo.com/neo/groups/sherline/photos/albums/332715421/light box/1915917769?orderBy=ordinal&sortOrder=asc&photoFilter=ALL#zax/1915 917769 and https://groups.yahoo.com/neo/groups/sherline/photos/albums/332715421/light box/927276457?orderBy=ordinal&sortOrder=asc&photoFilter=ALL#zax/927276457 The first photo shows the pieces of my set. The comment describes how they go together. The second photo shows die threading in action. I have threaded down to 00-90 inside and out. Jerry Kieffer threads to 400 per inch with DIY taps and dies on his Sherline lathe. Several years ago he demonstrated at NAMES how he makes his own [really] miniature taps and dies. I drove 800 miles R/T to attend. That presentation was worth the trip. One point that Jerry made was that when you are putting small external threads on a piece, it pays to use collets to hold the stock and then cut the protruding stock to size in short increments, thread, and then extend, size, and thread the next increment. Regards, Tom Bank ------- Re: Threading Posted by: chieftoolmakerx~xxearthlink.net glicker31 Date: Sat Apr 25, 2015 8:33 am ((PDT)) I should like to point out that Jerry Kieffer is in a special category all his own. AKA Mr. Good Buddy. He has an edge in that he utilizes a microscope. Jerry G (Glickstein) AKA Mr. Chief ------- Re: Threading Posted by: nbutterfield34x~xxyahoo.com nbutterfield34 Date: Sat Apr 25, 2015 10:39 am ((PDT)) Tom, Thanks for your reply and the photos. I mentioned #0-8 and #2-56 threads which I have made in the past but primarily my current work will be #4 thru #10 threading. Your technique is much like what I'm making which is a #0 MT arbor with a 2-3" lg. sliding straight shank for the Sherline tailstock and a sliding sleeve which slides over the straight shank. The sleeve will hold a 1/4" capacity tap and also a 13/16" round split die holder. The sleeve can be hand held for the smaller sizes and utilize a stop arm or handle for the larger sizes. Backing the tap out and backing the die off (reversing the spindle) will have to be done manually using the Sherline spindle handwheel with a handle applied. Starting either a tap or die is awkward, as I said before, because the Sherline variable speed motor has no torque, but it can be done. The "no torque" is a blessing in disquise, it's like a shear pin, I haven't broken a tap or tore up a die yet. Threading under power for small quantities certainly speeds things up. Also, in response to Greg P. So-called standard hex machine screws and nuts in the smaller sizes are not proportionately correct in size. For example, an off-the shelf #6-32 hex nut is .303" across the flats whereas a #6-32 scale model hex nut is .216" across the flats. The "standard" does not look right on a model, in fact it looks terrible. Model fasteners can be purchased but they get rather expensive and are not easy to find in many sizes. It is easier and cheaper to have Hex material in stock and make your own. Especially if you occasionally need brass hex. Neil ------- Re: Threading Posted by: "Ian Newman" ian_newx~xxyahoo.com ian_new Date: Sat Apr 25, 2015 1:40 pm ((PDT)) Hi N, Threading: It is best to use what are referred to in the UK as 'Swiss dies' - round, solid 'button' dies (UK terminology, I'm not sure what they are called in the USA). These dies are made to cut threads to a specific standard of fit. Less desirable are split dies, these are button dies with a split in them so they can be adjusted for class of thread fit. In use, you really should run a few practice threads and test the fit - once set up they are the most versatile as they allow you to adapt the fit of the threads to meet your specific needs. Note: Do not try to use split dies to make multiple passes, tightening the die with each pass, this is not how split dies are intended to be used (a little bit of arithmetic will show you that the difference between the loosest and tightest adjustment is only a couple of thou). Do not attempt to cut threads with die nuts (the hexagonal shaped dies) - they are designed for thread chasing and restoring, not for thread cutting (although hexagonal versions of the 'Swiss die' seems to be popular in the USA, so you are in that country you may need to check to see if a hexagonal die is for threading or chasing). Cutting the thread: Hold the work in the headstock chuck and brush the end of the work with a file to create a small taper to aid the start of the thread. Ideally, hold the die in a tailstock die holder, alternatively, use a conventional die stock but put the die in 'the wrong way round', i.e. with the engraved side of the die facing in to the socket of the die holder and against the shoulder. Lock the tailstock quill and loosen the tailstock to bed clamp so the tailstock can be pushed along the bed by hand. With one hand hold the die stock against the end of the quill - this will hold the die square to the axis of the lathe with the engraved side towards the bar being threaded. Slide the tailstock in to contact with the work and rotate the chuck by hand while pushing the tailstock/die on to the work. Tapping: Do not hold the tap in the tailstock drill chuck - both the tap shank and the chuck jaws are hardened and so the chuck will not grip the tap shank effectively. Ideally, hold the tap in a 'floating' tap holder (the type also used to hold reamers), alternatively, hold the tap in a tap wrench rather than the Tee shaped type of tap driver. Drill the work in the lathe then remove the tailstock drill chuck. Lock the tailstock quill and loosen the tailstock to bed clamp so the tailstock can be pushed along the bed by hand. With one hand hold the tap wrench against the end of the quill - this will hold the tap parallel with the axis of the lathe. Slide the tailstock in to contact with the work and rotate the chuck by hand while pushing the tailstock/tap on to the work. Hope this is useful. All the best, Ian ------- Re: Threading Posted by: "Martin Dobbins" trainnutzx~xxyahoo.com trainnutz Date: Sat Apr 25, 2015 2:13 pm ((PDT)) Nice work Tom. Neil, it sounds like great minds think alike. By coincidence, today I came across a couple of videos that might be interesting to anyone contemplating doing the same thing, the project is in two parts: Part 1: https://www.youtube.com/watch?v=MmGzzZEFSJU Part 2: https://www.youtube.com/watch?v=QmBeofg4d_A Martin ------- Re: Threading Posted by: nbutterfield34x~xxyahoo.com nbutterfield34 Date: Sat Apr 25, 2015 2:37 pm ((PDT)) Martin, Yes, I've seen those two videos. My tool is similar but much simpler and can be used for tapping as well as die cutting. I'll have photos and video available soon. Neil ------- Date: Fri, 19 Jun 2015 11:14:56 -0400 From: John Ruth Subject: Re: [OldTools] Don't you hate wen you lose a screw GG's Losing a screw from anything that is both antique and Stanley is a particular horror, because Stanley tended to continue to use whatever thread was used in their "Type 1" of anything. Witness the "approximately" #12-20 screws with the rounded thread profile used in the Bailey planes from the 1800's until into the 2000's! They held onto that until they went Metric! One thing to watch for is "Sellers' Threads" - fractional threads like 1/8-40. Today, we use numbered screw sizes for anything less than 1/4", but there was definitely a now-disused standard for fractional screws smaller than that. Victor Machinery has a good assortment of non-standard taps and dies in stock. (No relation, etc.) As a sort of P.S., an archive search will turn up the humorous story of a hardware store selling me a #14-20 die when I asked for a 1/4=20. There's only about .004 difference, hence the #14 has disappeared from common use. John Ruth -------- Date: Fri, 19 Jun 2015 17:59:48 +0000 (UTC) From: Erik Levin Subject: Re: [OldTools] Don't you hate wen you lose a screw Working on a pre-WW-II Westinghouse part, and the co-worker swore that an oil hole was messed up, since he couldn't get a 1/4-20 screw in and it was obviously 1/4-20, since nothing else is close. The service book (Westinghouse service books are available for pretty much everything they ever made, going back to the civil war) stated clearly that it was #14-20. He swore it was a misprint. In the end, he tapped out the hole. From that point on, the oil plug (#14-20) wouldn't properly seat. I have, kicking around somewhere, a #16 tap (I don't recall the threading) as well as a 0.125" and a 0.050-80 tap and die set (orthodonture wire size, apparently). History, short form: Machine screw sizes in imperial are 0.060" +0.013" *size, so a #0 is 0.060" dia, a #2 is 0.086" dia, etc. Odd sizes through #5 were once common, and occasional? #7. Even sizes larger than that. Smaller than 0.060, stacked zeroes like wire gauge: #00-90 is 0.060-0.013, or 0.047". Not to be confused with `miniature' sizes. They are often spec'd in imperial, but are actually metric sub-2mm sizes, added to the standard in the US in the late 1950's and intended to replace the sub#0 sizes. A miniature M1.2-0.25 is really close to a #00 in diameter (2 tenthousandths of an inch) but the thread is finer (approx 102/inch). I have seen old (pre-WW-I) references that give the size for machine screws using the multiplier 0.0132, which is suspiciously close to 1/76. Truly odd is wood screws, where the odd sizes are still fairly common. ------- What's the old fashioned way to make a tiny steel screw? [sherline] Posted by: professorguy2006x~xxyahoo.com professorguy2006 Date: Mon Jul 6, 2015 6:22 pm ((PDT)) I have a Sherline 4410 (metric long-bed) lathe with the manual threading attachment. I'm a machining novice and I need lots of advice. You can see my shop at http://professorguy.com/blog/workshop.html I've been trying to cut a small steel screw, but no luck. I can cut pretty small brass screws (the picture is taken on a coin): http://professorguy.com/watchmaking/project1/firstscrew1.jpg But in steel, I can't get a decent thread. The problems are myriad and I'm filling a box with my rejects. Tool dulls quickly. Or tip chips. Or doesn't cut at all and just pushes the tiny 1mm shaft (about 5mm long) out of the way. Or I accidentally pick too large a pitch and cut the shaft in half. Or... I've been using O2 drill rod, which seems fairly easy to shape to the correct profile with a simple right-hand HSS cutter. But when I go to use the 60 degree tool, the O2 steel suddenly seems too tough. I tried to harden the HSS steel tool after polishing the tip, but I'm told I actually softened the tip by using too low a temperature. It is possible I'm getting the tip cherry red during the grinding process to make the 60 degree tool (I grind them myself) and that softens the tip. How do I grind a 1/4" HSS blank into a 60 degree shape without heating too much? Or, if that's impossible, how do I harden HSS? I don't want to use carbide, or even too exotic steel, I'd rather stick to methods from the Victorian era. They obviously made fine steel screws then. How'd they do it? Thanks in advance for any light you can shed. ------- Re: What's the old fashioned way to make a tiny steel screw? Posted by: dcclark111x~xxcomcast.net a3sigma Date: Mon Jul 6, 2015 6:37 pm ((PDT)) Here's a suggestion to keep a small piece from springing away from the cutter: https://groups.yahoo.com/neo/groups/sherline/photos/photostream/light box/443460216?orderBy=mtime&sortOrder=desc&photoFilter=ALL# David Clark in Southern Maryland, USA ------- Re: What's the old fashioned way to make a tiny steel screw? Posted by: jowhowhox~xxyahoo.com jowhowho Date: Mon Jul 6, 2015 10:30 pm ((PDT)) You could try leaded, free machining steel. It may not get as hard as O2 though. It will cut nicely. For annealing, hardening, and tempering consistently, put the screw on a larger piece of steel and heat that. Keep the flame away from the screw. Using screw plates (old school) or thread milling (new school) might work. When you grind the HSS bit, it should be held in something massive. The mass makes it cut faster. I hold them in a Chinese universal grinding fixture. If you hold it in your fingers, it mostly bounces and gets hot. Touching it up can be done by hand. HSS should keep its temper even if you get it very hot. Don't quench it if it is very hot. Finish the bit as you would a graver, in a jig on an arkansas stone. Grinding fixture: http://www.ebay.com/itm/SHARS-UNIVERSAL-VISE-MILL-MILLING-GRINDER-GRIND ING-FIXTURE-NEW-/300876103862 Justin -------- Re: What's the old fashioned way to make a tiny steel screw? Posted by: "Grant Maizels" grant.maizelsx~xxgmail.com grant.maizels Date: Tue Jul 7, 2015 5:19 am ((PDT)) I also have a sherline lathe and mill and have been working towards starting the multi-decade project of building a watch. Of course I'm still at the stage of building tools to build the tools to build my watch. I carefully follow the build being done by the gentleman at watchmaking.weebly.com. His Cowells lathe does not do screwcutting and he cuts all his threads with dies held in a tailstock die-holder. He does use this to make screws from small O-1 Drill Rod, I think the smallest on his site is M0.5, but he mostly uses M1.5. His site is well worth visiting if you are making a watch. He documents all his mistakes and failures along with success, making it much more educational then books. I have just finished a making a die holder to hold 1" and 13/16" dies on my sherline; but need to make more, smaller holders, to hold my 16mm, 12mm and 8mm external diameter dies. The suggestions about using "Leaded Steel" e.g. 12L14 make sense and, for small sizes, the cost should be quite reasonable. It is probably much easier to get in the US then here in Australia. The smallest I have been able to get is 8mm dia. Even just going to 1214 would probably help. Grant ------- Re: What's the old fashioned way to make a tiny steel screw? Posted by: jlkiefferx~xxcharter.net n2562001 Date: Tue Jul 7, 2015 7:42 am ((PDT)) The first small watch screws were made with the help of screw plates as I understand it. It has been said that the screw plates were made with free hand formed taps. At any rate, examples of the early screw plates and screws are pretty crude by today's standards The Sherline Lathe and threading attachment can single point thread carbon steel down to about .010" in diameter and up to about 500 TPI so equipment capability is not an issue. I occasionally do demonstrations at seminars and workshops single point cutting Taps in this size range. However there are a few requirements that allow this to happen. (1) Repeatability of the threading system is absolute must. This is assured by spring loading the Carriage and gear train per the photo under my Name. (2) I only use the highest quality W-1 where carbon steel that has proven to generally be the easiest to machine. In addition, it is only purchased after being assured by the manufacturer/supplier that it has the best machinability characteristics available. (3) It has been my experience that HSS steel provides the cleanest thread cut in steel. Again, I only use the highest quality that can be purchased. It is then sharpened using 1200 grit diamond wheel on a non heat generating Accu-Finish grinder. At no time should this tool be subject to heat of any type at any time. It is ground per the photo under my name to allow the tool to thread up to a shoulder. (4) The tip of the threading tool MUST be set dead center to the spindle center line of rotation. This is done by sharpening a piece of stock to a pencil point that is extremely sharp in the lathe spindle that runs true under magnification. The cutting tool tip is then set using the sharp tip as a guide under strong distortion free magnification from the back side of the lathe. The back side allows obstruction free viewing. (5) Thread length should be no longer than can be supported by the work piece without deflection. This should not be an issue when machining screws. For multiple common size screws, you may want to consider commercial Taps and Dies. Jerry Kieffer ------- Re: What's the old fashioned way to make a tiny steel screw? Posted by: "Stan Stocker" skstockerx~xxcomcast.net stanstocker Date: Tue Jul 7, 2015 7:48 am ((PDT)) Greetings, If you insist on single pointing, save yourself much pain and hassle and go to AR Warner and get their threading insert and holder. That will eliminate your toolbit grinding issues and make threading via single point a joy. Take shallow passes and use a threading oil such as Mitee, Vipers Venom, or some other heavy sulfurized cutting oil. As for the traditional way of making watch screws before screw machine days: 1) Chuck up raw stock. 2) Turn major diameter of threaded portion, finish underside of screw head, bottom chamfer if desired. On first screw chamfer the lead in area of the shank. 3) Using a V tool, PARTIALLY part off the screw blank such that the V notch forms the bevel around the edge of the screw head to be and the bevel of the next screw major diameter (depth of cut will be to about minor diameter, requires experimentation). HINT: V tool upside down on rear toolpost, saves tool swaps! 4) Brush on some cutting oil, grab a shop made screw plate and thread the screw (under power, low speed). In factories the screw plate might have hundreds of identical threading slots. When the head bottoms out on the plate, the unfinished screw will shear off of the stock. You now have a screw with a somewhat pointed head and a nice perimeter chamfer firmly screwed into the screw plate. 5) Repeat until your screw plate has as many screws as you need plus some spares. 6) Mount screw plate on grinder or mill table and level off the tops of the screws. Can do with silicon carbide papers of increasing fineness on a surface plate too. Think head polishing jig, just polishing a batch at once. 7) Slot the screws -- easiest with a horizontal mill and a fine slitting saw. Tedious with a screw slot file. 8) Deburr and polish as much as possible while on the plate, then unscrew the screws. 9) Get real tired of this BS and invent a screw making machine around 1860 or so... :-) 10) Polish, degrease, blue as usual. To make a screw plate requires a tap. So you either buy one or make one. You'll need taps anyway, as the plates need to be tapped. You might have a look at Archie Perkins Watchmakers Lathe and Vintage Watch Restoration books, and also Daniels Watchmaking. It's old tech, and fairly low tech, but there are many lessons the master watch guys have learned the hard way and pass on to us for free if you have library access and an interlibrary loan system. There's always Amazon, and if you are in the US the NAWCC library is great. For $72 a year there are darn few horological books I can't get my hands on. As a machining novice who wants to make watches, you need to read the watchmaking books, and also anything related to small machines. I sold all my WW stuff and my jewelers lathes and have never regretted it. Sherline and Taig work so much better and easier. If you are in the eastern US, try to go take the lathe class Jerry Kieffer teaches once in a while at the NAWCC in Columbia, PA. You will see and learn how to do some things on Sherline machines (quickly and repeatably to boot) that the die hard traditionalists insist can only be done on old school machines. Don't overlook miniature versions of box tools and other goodies from turret lathes if you need to do more of these sorts of limited production run items. Although I have CNC equipment, I can promise you that unless you have a stock feeder, it's quicker to do this stuff with turret tooling and maybe some gang tooling on the cross slide than via CNC. For info on Sherline scale turret machining, have a peek at: http://downrivertools.com/about-downriver-tools No connection other than a pleasant conversation with the owner several years ago at Cabin Fever, and I bought some of his plans. Have fun, Stan Stocker Bentonville, Virginia ------- Loose faceplate [myfordlathes] Posted by: n1arbx~xxyahoo.co.uk n1arb Date: Fri Jul 24, 2015 1:44 pm ((PDT)) Firstly may I say that although I rarely post (and as a result had to re-subscribe), I read virtually every post and think this is a fantastic group. The reason for this particular post is that at long last I went to use a faceplate that came with bits and pieces for my ML7 and found that is such a loose fit on the spindle that it is more or less useless. It screws on and seems to have the same number of tpi as the spindle but is just too large. The threaded internal hole diameter is 1.08". The recess at the back is Myford size. I then started wondering how this could arise -- is it intended for another lathe and if so what? The threads don't look particularly bad so it is not wear. Was it just made wrong. In view of the the price of new ones I am reluctant to throw it away. Any ideas and any suggestions what I can do? It is cast iron and I'm not sure if my skills would go to doing an insert (with no faceplate to mount it on anyway!) and a new thread. Stephen ------- Re: Loose faceplate Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Fri Jul 24, 2015 4:48 pm ((PDT)) Boring out the loose threads, pressing in an insert (possibly with a little Loctite) and rethreading is exactly what I’d so. Assuming that you have a chuck, mounting the faceplate shouldn’t be a huge problem. Just attach something to the face of the faceplate and grip it with your 3 or 4-jaw chuck. Possible choices include a piece of pipe with a floor flange to bolt to the faceplate (face the floor flange to ensure that it is perpendicular to the axis of the lathe) or a disk of ˝-inch thick aluminum or steel bolted to the centre of the faceplate. Even a disk of plywood would probably work for a one-off job. Perhaps you could borrow a Myford faceplate from a friend and bolt the two face-to- face. If you make a mistake you can always bore out the insert and try again. ------- Re: Loose faceplate Posted by: n1arbx~xxyahoo.co.uk n1arb Date: Sat Jul 25, 2015 1:17 pm ((PDT)) Thanks for the advice. I have an old backplate which also doesn't fit and tried it out on that today. Only having a stud-lock loctite which I wasn't sure would work, I bored a very slight taper to the new insert and the plate and heated the backplate with a blowtorch and dropped it on. It seems to be solid. I've now ordered a tap from RDG. As you say, if it doesn't work, try again. Stephen ------- Re: Loose faceplate Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Sat Jul 25, 2015 4:14 pm ((PDT)) If you single point screwcut the thread almost to depth and then finish with the tap you’ll probably get a better result than trying to thread with the tap alone. ------- Re: Loose faceplate Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood Date: Sat Jul 25, 2015 5:56 pm ((PDT)) You will probably need to skim the faceplate after fitting the new thread insert, as it almost certainly will not be perfectly concentric. In fact, it's not a bad idea to do this with any new faceplate, to make sure it is spot on when fitted to *your*lathe. David ------- [Actually a question about cutting screw threads on a lathe] Setting over top slide on ML7 [myfordlathes] Posted by: "Haydut1200" haydut1200x~xxgmail.com haydut1200 Date: Sun Aug 9, 2015 3:19 am ((PDT)) I've decided to have a serious go at screwcutting on my ML7. The only thread I cut until now was for a Dremel, and I could probably have done that with a junior hacksaw. :) I'm thinking of making, or trying to make, an ER25 chuck to fit on the ML7 mandrel. On my first attempt at cutting an external 1.125" WW thread, I made the mistake of setting the topslide over at the wrong angle. Once I realised this, I found that setting it to 27.5 degrees is right at the end of its travel, and with no marks to line it up. The question I have been leading up to is, is there an easy way to accurately set the ML7 topslide to 27.5 degrees? Although I am unlikely to want to screwcut any metric threads, how would I would I go about it if I can only set the topslide to around 27.5 degrees? Martin ------- Re: Setting over top slide on ML7 Posted by: "David Everett" dernhx~xxyahoo.co.uk deverett2003 Date: Sun Aug 9, 2015 3:46 am ((PDT)) GHT used to recommend swivelling the topslide round to half the thread angle and feed in using the topslide handle. Some other exponents suggest swivelling round a degree less so that when the topslide is infed, the tool shaves the leading edge of the thread without fouling the trailing edge. However, Tubal Cain preferred to keep the topslide parallel and feed in using the crossslide. When getting deeper in the thread cutting process, he would advance the topslide 1 thou and then retract the topslide by 1 thou at the same depth before continuing at the 0 setting. I've tried both methods but usually I cut to approximate depth and then finish off with a die. Not much good if you are wanting to cut a 1-1/8" diameter thread, I realise. Unless you are desperate to make your own ER25 chuck, why not just buy a suitable backplate casting and fit an ER chuck to it? Doing it that way ensures the most accurate mounting for your collets. I won't get into an argument about the accuracies of collets or them versus a 4 jaw chuck, that's for a whole new thread! Dave The Emerald Isle ------- Re: Setting over top slide on ML7 Posted by: "Haydut1200" haydut1200x~xxgmail.com haydut1200 Date: Sun Aug 9, 2015 10:10 am ((PDT)) Thanks for the info, Dave. I'm not desperate to make an ER25 chuck, in fact I have one with MT2 for my WM14 drill/mill that I can use in the ML7, as long as I only want to hold short pieces. However, making one will give me something to do on the lathe now I am retired, and might even be a selling point when the time comes. Cheaper than buying, too. Cheers, Martin ------- Re: Setting over top slide on ML7 Posted by: "Kevin" tadpolex~xxbtinternet.com klokenz Date: Sun Aug 9, 2015 2:53 pm ((PDT)) Martin, I had need to do this once. First stop was to look in a few books. GHT makes mention of it, but I recall that he was a bit vague, seemed to be calling for bars to be laid in the Tee slots in order to provide fixing holes where there is normally just air. Having pondered his idea for a while, and being in somewhat of a hurry, I went my own way.... made an adapter plate from 1/8th inch steel sheet which overlapped the cross-slide. It had holes for short countersunk screws to go into Tee-nuts to hold it in place, and suitably placed holes in the areas overlapping the cross-slide to take screws locating in the top-slide curved slots. By this means the top-slide could be swung round to any required angle. Sitting on the adapter plate meant that it was raised up by the thickness of the plate, but I could lower the tools needed for this job enough to accommodate. For setting the angle I made a simple angle template and used it between a bar held in the chuck and an edge of the top-slide. I was concerned about rigidity, which would clearly be less than normal, but turned out to be no problem for the job. I was making a fly-cutter which needed rather precise angles, so it was silver steel with an interrupted cut. It didn't look pretty, but got the job done! Kevin, England ------- Re: Setting over top slide on ML7 Posted by: "Ian Newman" ian_newx~xxyahoo.com ian_new Date: Mon Aug 10, 2015 12:48 am ((PDT)) Hi Martin, Setting over the compound slide for 55 deg (Whitworth) threads: The angle you want is "just less than half of 55 degs" -- so it does not need to be exactly 27.5, don't get hung up on exact angles and fractions of a degree. To set any angle on the compound, it is wise to never rely on the graduations marked on the lathe. Use a protractor such as: http://images.toolbank.com/images/extralarge/MAW44.jpg Or the one that is included in a combination square: http://www.rdgtools.co.uk/acatalog/Moore---Wright-Combination-Set-MW 521-01-MW52101.html All the best, Ian ------- Re: Setting over top slide on ML7 Posted by: garthnx~xxpbt.co.za garthn444 Date: Mon Aug 10, 2015 3:03 am ((PDT)) If you have a PC and printer, download Google Sketchup (free) and print your own patterns. Cut out with a pair of scissors and you have a custom 27.5 degrees "protractor". I find it very useful for any pattern marking -- glue the paper onto what you want to mark using Pritstick -- the paper comes off afterwards by soaking in hot water and acetone cleans the glue off. You can glue something like the angle onto a thin sheet of aluminium to be able to cut and file that accurately, for a permanent solution. It's a whole lot cheaper than 83 pounds. ------- Re: Setting over top slide on ML7 Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Mon Aug 10, 2015 6:39 am ((PDT)) As Ian says, don't get hung up on getting exactly 27.5 degrees. The point of setting the topslide over is to stop the tool having to work hard cutting on both faces. When it does this on a lightly built lathe you are more likely to get chatter. Setting the slide at exactly 27.5 degrees means that all the cutting action occurs on one face, with zero on the other face. Setting it above 27.5 means that you will get a series of steps on one shoulder of the thread, as each pass is slightly shallower than the last. Setting it below 27.5 means that both faces of the tool are doing some work. A degree or two low is not a bad idea, as it means that you are taking a light shaving off the thread shoulder on each pass, which should give you a better finish (if the tool is sharp). Regards, Alan ------- Re: Setting over top slide on ML7 Posted by: jonathanagibbsx~xxgmail.com jonagibbsuk Date: Tue Aug 11, 2015 1:18 am ((PDT)) If you normally have your topslide at 90 degrees to the cross-slide you can also just put on half the cross-slide cut with the topslide and this results in an angle of arctan(0.5) = 26.565 degrees. The advantage of this method is that when the thread is to depth (direct reading of the cross-slide rather than topslide reading multiplied by cos (set-over)) you can easily broaden it a thou at at time with the topslide. If you have Martin Cleave's book, this is the method he said he used. Hope this helps Jon ------- Date: Wed, 19 Aug 2015 16:15:18 -0500 From: Brent Kinsey Subject: [OldTools] Screw box help Oh helpful Galoots, I have an old screw box with matching tap that I want to use. The tap is in sad shape with cutting edges that are rounded over and dull as a butter knife. I received it this way and think someone at some point took a wire wheel to it. http://galootcentral.com/component/option,com_copper minevis/Itemid,/place,thumbnails/album,748/ What is the best way to approach sharpening a screw box tap? I am assuming I should use a large taper file in between each tooth, then a slightly convex file on the face in the flutes. Is there something I am missing? Any advice appreciated. Brent A Kinsey ------- Date: Wed, 19 Aug 2015 18:13:01 -0400 From: Claudio DeLorenzi Subject: Re: [OldTools] Screw box help Hi Brent. I would not touch the outer sides at all (apart from dressing the burrs) -- that's the diameter of the thread it cuts (then it won't match your screw). You should only touch the grooves going along the length of the tap to sharpen. There is something on one of Roy Underhill's books on these if you want to look it up. Claudio ------- Date: Thu, 20 Aug 2015 00:08:50 +0000 (UTC) From: Erik Levin Subject: Re: [OldTools] Screw box help Having sharpened a good number of taps for metal (some well, some not so well), I will offer the following advise: Option 1: DO NOT TOUCH THE OUTER PROFILE. Sharpening happens ONLY on the cutting face in the flutes. I am not sure what the angle appropriate for this is in this case, as most metals need a tap with anything from 0 degrees to about 5 degrees rake, but it isn't as critical as that the edge between the face and the outer profile being dead clean. No rounding, no nicks. I would guess, by the method of orifical extraction, that maybe 5 degrees would be appropriate for most woods, but this is nothing more than a guess. If there is a clear angle already, follow it. The tool I use when working by hand to sharpen is a diamond file. If I can, I prefer to use a grinder and fixture to present a consistent angle and reduce the risk of rolling an edge. I have used powered tools, such as a die grinder -- use a treadle dental drill if you want to avoid circulation of electrons -- with stones, diamond points, and diamond wheels on larger taps, where there is a bit more leeway. Only the first few threads actually cut. Once the profile is the final profile, no more cutting is going on. This leads to Option 2: Ever so carefully, bring the taper at the lead end back a thread or so. Note that the lead has a taper, and the cutting is distributed amongst a few threads. The lead is not a cone. Each cutting edge is a little bit higher than the rest of the little bit of thread. I have ground these a number of ways, but for a large diameter tap, a grinding wheel is fine. There is a technique, but basically the lead is made a cone to the root depth of the thread, then each thread section between the flutes is relieved back of the cutting edge a little bit to prevent binding. If the lead is worn, you might make the tap a thread or two shorter than it started by the time you are done. ------- Date: Thu, 20 Aug 2015 09:59:12 -0700 From: Kirk Eppler Subject: Re: [OldTools] Screw box help On Aug 19, 2015 Erik Levin via wrote: > DO NOT TOUCH THE OUTER PROFILE. Hate to say it, but to my uninformed eye, it looks like the leading edges are already fouled from a wire wheel. Maybe it's just the first few, but they look really rounded off. I would think that if you have good edges at the back, you can mess with the front to make them cut, and count on the more-rear-ward ones to refine the cut to fit the die. Kirk Eppler in HMB ------- Date: Thu, 20 Aug 2015 13:38:09 -0400 From: Ed Minch Subject: Re: [OldTools] Screw box help Another option if the threads are rounded over would be to file them until they are sharp, then adjust the screw box to cut threads to fit the tap. This way the finished product would not be any particular dimension, but the two pieces would fit each other. Ed Minch ------- Date: Thu, 20 Aug 2015 14:33:22 -0500 From: Brent Kinsey Subject: Re: [OldTools] Screw box help This was kind of my thought as well. Badly rounded over and not full dimension at this point anyway. May have to adjust cutter in screw box to accommodate. But, I am going to try to dress the faces of the flutes first as suggested and see if that will work. I don't know that there is any down-side to having the bottom of the threads on a wooden nut rounded as long as I ease the edges of the threads on the screw portion. In my minds eye I am thinking ACME style threads which are rather flat. I will take the least abusive approach first with the flutes and work from there. Thanks for all of the input. Brent A Kinsey ------- Date: Thu, 20 Aug 2015 20:34:21 +0000 From: David Nighswander Subject: Re: [OldTools] Screw box help My apologies for the abuse of bandwidth. Errant key strokes be dahmddd. When I sharpen taps I take the approach that each tooth is a chisel that has to cut in a proscribed arc. The cutting edge must engage the material, wood, steel, or plastic, and the rest of the tooth has to clear while supporting the cutting edge. Wood threading taps have the unenviable task of cutting both with and across grain. That requires a compromise edge angle. The saving grace of the operation is the tap is held at a fixed angle and depth of cut that is determined by the taper of the lead threads. Long taper taps start easier and in my opinion cut better threads than shorter ones. Smaller chip thickness means less load on the tap tooth and the material so shear angles can be higher for smoother cutting. As a reference consider starting a hole with either a plug tap or a bottoming tap. Plug tap will win hands down. It was suggested that the back threads are a guide more than cutters and I agree with that premise. They can be considered cutters in waiting with the option of sharpening the tap like a pencil. Moving the taper towards the back and obtaining a fresh edge through reduction. Long explanation of a simple process. For those that already know, sorry for the length. ------- Date: Tue, 25 Aug 2015 10:23:27 -0800 From: Phil Schempf Subject: Re: [OldTools] Screw box help Galoots - While digging around for other info I found this reference on sharpening taps. http://www.wkfinetools.com/contrib/jThompson/sharpTap/sharpeningTap-1.asp From Jim Thompson no less, continuing to keep galoots on the path. May be of some use. Phil ------- Super 7 Imperial Gearbox lathe conversion to Metric [myfordlathes] Posted by: nevillerhendersonx~xxgmail.com nevillerhenderson Date: Fri Sep 18, 2015 1:59 am ((PDT)) My 1st post here, although I've been lurking on the list for a while. My question is I'm suddenly confronted with producing a metric thread of M12 x1.75 pitch (14.5 something TPI ) and I have ML Super7 imperial lathe with gearbox and I see that for a fairly large consideration Myford will supply a conversion set of primary gears to give metric threads such as the one that I need to produce. Has anyone any experience of using these conversion gears and are they worth the investment? I'm fairly new to this lathe, having graduated from a small Chinese variety. Any advice welcome. Regards Neville in Athens Greece ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "Mike Crossfield" miked.crossfieldx~xxbtinternet.com Date: Fri Sep 18, 2015 2:21 am ((PDT)) Neville: Since you have a gearbox there is a very simple way of cutting metric gears by simply changing one gear on the end of the banjo, and selecting the right ratio on the 'box. There was a very good article by Brian Wood describing the method in Model Engineers Workshop issue 212. According to the article, for a M12 x 1.75 gear you need a 33 tooth gear in place of the standard 24 tooth item and a gearbox setting of 20 tpi. Simples! HTH Mike ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "Andrew Moyes" admx~xxamoyes.fsbusiness.co.uk moyes_a Date: Fri Sep 18, 2015 2:41 am ((PDT)) The official metric conversion set is not worth the money and definitely not worth the trouble of setting up every time you want to change from imperial to metric. You can cut most of the threads you will need using just 33 and 34 tooth wheels which you should be able to get from Myford. For 1.75mm pitch, just replace the first wheel in the chain after the Tufnol tumber reverse gears by the 33 tooth one as in this chart and set the gearbox levers as shown. The results are an approximation but near enough for most model engineer purposes. Most threads are accurate to better than 0.2%. mm pitch driver gearbox TPI 0.40 34T 10+fine feed 0.45 24T 56 0.50 34T 8+fine feed 0.60 25T 44 0.70 21T 32 0.80 30T 40 1.00 34T 36 1.25 33T 28 1.50 34T 24 1.75 33T 20 2.00 34T 18 2.25 34T 16 2.50 33T 14 3.00 34T 12 3.50 33T 10 4.00 34T 9 4.50 34T 8 Andrew M ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Fri Sep 18, 2015 7:04 am ((PDT)) To further answer your question about the metric kit: One of my first purchases after getting my Myford (years ago when I had hair) was the metric conversion banjo. In the intervening years I have never used it although I often cut metric threads for camera accessories and such. For my purposes the approximations such as Mike mentioned are more than good enough. And far less effort than changing the banjo. Depending on your available gears and accuracy requirements there are other choices than the one listed by Mike. For example, using a 30-T and gearbox set to 18 or a 20-T and gearbox set to 12 you will be within 0.8% of 1.75mm pitch. ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: nevillerhendersonx~xxgmail.com nevillerhenderson Date: Fri Sep 18, 2015 12:15 pm ((PDT)) Thanks to everyone that answered. I will go looking for a 33T and 34T wheel to start with and see how I get on with that. I agree on my Chinese lathe that I had I managed most threads accurately enough by some weird gear combinations that worked very well. Many thanks again Neville in Athens ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: colin.bowler9x~xxyahoo.com colin.bowler9 Date: Fri Sep 18, 2015 10:12 am ((PDT)) I have been watching this post with some interest as I have a requirement to cut a 0.58 mm metric thread with my Imperial ML7 (no gear box). This is a fairly common thread for camera adapters but the closest standard thread appears to be 0.70 mm. Is this close enough or can anyone recommend appropriate gearing? Thank you, Colin ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "Alan Moore" a.j.moorex~xxbtinternet.com Date: Fri Sep 18, 2015 10:35 am ((PDT)) Colin, 0.58mm pitch equates to 43.79 tpi. There is a standard setup in the manual for 44tpi, which only gives 0.47% error. This should be close enough for most purposes. Regards, Alan ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "David Littlewood" davidx~xxdlittlewood.co.uk dmlittlewood Date: Fri Sep 18, 2015 11:20 am ((PDT)) Colin, I'm very surprised about the 0.58 mm thread; most camera filters have a 0.75 mm thread (some smaller ones have 0.5 mm threads). I strongly suggest you check the camera thread, if that's what you are making something for. If it's for something else and it really is 0.58 mm, then as some other kind soul told you, the nearest imperial equivalent should serve OK. David ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Fri Sep 18, 2015 11:43 am ((PDT)) I’ve never seen anything with 0.58mm threads. That said, 0.60mm (43.33 tpi) is a standard metric thread for 3.5mm screws. Are you certain that you have measured accurately? You can get 0.6013mm using a 25T driver with the gearbox set to 44tpi. I have a gearbox on my S7 but I assume that you can get something similar without using a gearbox. ------- Re: Super 7 Imperial Gearbox lathe conversion to Metric Posted by: "Colin.bowler9" colin.bowler9x~xxyahoo.com colin.bowler9 Date: Fri Sep 18, 2015 12:15 pm ((PDT)) Thanks for the reply Ken and David. Unfortunately the required thread size is .58mm. I'm trying to make an adapter to attach an older Canon G6 camera to a stereo microscope. I'll give it a shot using the closest thread I can come up with. Glad to hear this isn't as common for optical applications as I thought. Cheers, Colin ------- Grub screws [myfordlathes] Posted by: "Bill Bedford" billbx~xxmousa.biz billbuk2000 Date: Fri Oct 16, 2015 11:46 am ((PDT)) Can anyone suggest a source of 3/16" BSF grubscrews to replace the gib strip adjuster on my ML4? Bill Bedford ------- Re: Grub screws Posted by: "Peter Dobson" peterdx~xxmodelrail.net peter317217 Date: Fri Oct 16, 2015 12:43 pm ((PDT)) Yes - that one is easy. Use 2BA -- it is as near as you could want. Other BSF or BSW are a PITA -- there would appear to be no alternatives. Peter Dobson ------- Re: Grub screws Posted by: "Bill Bedford" billbx~xxmousa.biz billbuk2000 Date: Fri Oct 16, 2015 1:33 pm ((PDT)) Maybe, but a 2BA screw won't go into a hole that's tap 3/16 BSF -- I've tried. Bill Bedford ------- Re: Grub screws Posted by: "Peter Dobson" peterdx~xxmodelrail.net peter317217 Date: Fri Oct 16, 2015 1:52 pm ((PDT)) Maybe the threads are a bit clogged up. Run a tap thro' first. It worked for me -- on a Myford. Peter D ------- Re: Grub screws Posted by: "David Ingram" davidi1107x~xxyahoo.co.uk davidi1107 Date: Fri Oct 16, 2015 3:14 pm ((PDT)) Hi. Please note that BSF and BA screws have a different thread angle, BSF is 55 degrees, BA was our "British version of the metric system" and the thread angle is 47.5 degrees. This is why there is a bit of a interference fit if you try to mix the forms. Hope this helps. Dave ------- Re: Grub screws Posted by: harry.wilkesx~xxsky.com harry.wilkesx~xxsky.com Date: Fri Oct 16, 2015 11:39 pm ((PDT)) Got mine from Myford Lathe Spares, ML7. http://www.lathespares.co.uk/ ------- Re: Grub screws Posted by: java_needx~xxyahoo.com java_need Date: Mon Oct 19, 2015 2:08 am ((PDT)) My ML4 also uses 2BA for the gib screws ------- Re: Grub screws Posted by: "Tim Stevens" bobweightx~xxbtconnect.com bobweight Date: Tue Oct 20, 2015 10:06 am ((PDT)) The dimensions for 3/16 BSF and 2BA threads are very similar, so as long as you are not using more than about 1/2" of thread in engagement either will serve. It is therefore likely that anyone measuring a grub screw to identify the thread may plump for the wrong (but very near) size. A further source of confusion is that the hexagon size for 2BA is sometimes used for 1/8W and 3/16BSF fasteners. Of course, we all know that BA and BSF have quite different thread angles, and the pitches are metric and inch, but you can still hold a pair of used threads up to the light and not see a difference. Cheers, Tim ------- Re: Grub screws Posted by: "Bill Bedford" billbx~xxmousa.biz billbuk2000 Date: Tue Oct 20, 2015 10:51 am ((PDT)) I had a delivery of 3/16" BSF grub screws and nuts today, and I can confirm that 2BA will go no more that half a turn into the BSF nuts. Bill Bedford ------- 3 start acme thread of 10 tpi on myford Super 7B [myfordlathes] Posted by: gwe1x~xxbigpond.com.au sparrowmudgee Date: Sat Oct 31, 2015 3:46 pm ((PDT)) Is it possible to cut a 3 start thread on a myford supper 7B as I am restoring a Myford cut off slide from a capstan setup. Many thanks GARRY ------- Re: 3 start acme thread of 10 tpi on myford Super 7B Posted by: "Ken Strauss" ken.straussx~xxgmail.com kstrauss7 Date: Sat Oct 31, 2015 8:11 pm ((PDT)) It is a pain but yes. See http://www.practicalmachinist.com/vb/general-archive/how-do-you-cut-mu ltiple-start-threads-83607/ for some good info. I’ve used the “advance the compound” technique described there to successfully cut 2-start threads. For 3-start thread you just need to do things one more time. Alternatively the method discussed in message #6 of the above link should work well if are turning between centres with the headstock centre held in a 3-jaw chuck. ------- [Actual subject is cutting threads in wood] Date: Tue, 3 Nov 2015 22:55:13 +0000 (UTC) From: Thomas Conroy Subject: Re: [OldTools] Gum lumber Claudio DeLorenzo emailed me off-list: "Would be interested in knowing more about the presses you fixed up and how you made the threaded parts? The screws seem fairly straight forward, the 'nuts', not so much..." I wrote a reply, then thought it might be of general interest. So: Happily, the female threads seem to be far more sturdy than the male threads. I've never had to do any repairs to them. Presses made in the last thirty years or so are most often made with the standard Conover- style Chinese screwboxes, so if they jam (very common w. both old and new presses) you can open out the female threads with the right size tap. Running over male threads a second time with a screwbox usually just chips it all to hell and ruins the screw. With new presses, sometimes the screw is so badly chipped that it has to be replaced, and this can be made with a new screwbox. With an old press, if the screw is trashed you can hand-carve an entirely new screw on a turned blank. I've done this maybe five or six times, don't want to do it again if I can help it but probably will have to. It's not that hard, just boring. Start by cutting a spiral on the blank with a dovetail saw with a stop clamped on, use a chisel to cut down from the crest, fair it in and provide slop with a file. Check progress in the female thread using carbon paper to highlight places to pare away. I thought St. Roy went through the whole process of hand-cutting screws with a chisel in 'The Woodwright's Workbook," but I don't see it in a fast glance -- but somewhere in his books or show (at least three or four episodes on wooden screws) he says enough. If an old press has screws that jam, and you don't have the right size tap (you never do with an old press) then open up and fair the screw with a chisel and file, like the last stages of hand-carving a screw. I've almost always used screwboxes and taps for threading wood. With proper choice of wood (black locust, walnut, well-aged beech, maple in that order; **never** cherry, oak, or ash, and cut a test screw in the wood you want to use -- DAMHIKT) and lubrication (slather with BLO before cutting) and in good condition screwboxes give completely satisfactory screws. Toolmarks on old screws show that they were almost always cut with screw boxes. The best screwboxes made are German, and they have the proper pitches for their diameters (which the Conover-style ones don't), but they are damned expensive. A proper screw-cutting lathe is capable of cutting the best wooden screws, but you need one that will handle a pitch of 4-12 t..p.i. to 2 t.p.i., and you need special cutters for threading wood. I'm willing to accept shopmade router jigs as a possibility, since the best screwcutter in the world (Frank Wiesner in Australia) uses one -- but he's a German-apprenticeship-trained professional, not just professional woodworker but professional screwcutter, and he knows exactly what he's doing. But I bought a commercial router jig once, from wonderful and helpful people, and when it arrived it -- well, leave it at "wasn't worth the money." Apart from anything else, the jig registered on the uncut surface of the wood blank, so unless the blank was an extremely true cylinder you got a horribly irregular screw. So no hand-turned blanks, no commercial dowels, you had to use high-precision dowels -- which they sold, as a convenience. This is just dumb. The entire expensive high-precision surface of the blank gets cut away when you cut the screw. A screwbox registers on the part of the thread you have already cut, so there is no need for high precision. If you are going to use a screwbox you can easily hand turn a cylinder true enough on an ordinary woodworking lathe, and you can turn it as a single unit with the handle and its bearing surface. So no router jigs for me. Running long here, but one more thing: I can't emphasize enough the importance of having the screw and the handle turned from one piece of wood, and having the bearing surface at the base of the handle being large and sturdy. If a screw is just glued into a hole in the handle, the force of closing the press is often great enough to break the glue joint and pull the screw right out of the handle. A handle that is pegged onto the screw, the peg will be snapped. I've had adequate results by threading the screw into the handle and also gluing it in (leaving an unthreaded length to turn in the cheek and receive the garter), but it is hard to get this straight. One-piece is best. And bearing surface: this is apt to wear rapidly if narrow, and to wear a track into the chop; and if there isn't enough "beef" behind the bearing surface it will chip out. For a 1-1/4" screw I want a base to the handle at least 1-3/4" diameter (i.e. a bearing surface 1/4" wide), and I want the base of the handle to go back as a full-diameter cylinder for at least 1" before it necks in for a comfortable grip (this is for handles without a tommy bar, ones that you just turn with your hand). Note that a traditional wood-screw vise is likely to have a bearing surface at least 1/2" wide, and a screw diameter 2" or more in diameter with a pitch closer to 2 t.p.i. than 1 t.p.i. As Adam said, there is lots I've said about wooden screws back in the archive. Lots and lots. And lots. And.....lots.....zzzzzzzzzzzz Tom Conroy Sleep well and prosper. ------- [Picking up and extending an existing thread] Cutting threads [atlas_craftsman] Posted by: c.hintonx~xxhotmail.com nm0l Date: Wed Feb 24, 2016 1:59 pm ((PST)) I have a 1.0 in. round with 1.0 inch of threads. Is it possible to chuck this round up and extend the threads to 2.0 inches? Can I set up for the 13 threads per inch and engage the carriage feed and slip the round in the chuck so the bit is in the first thread groove? Or is there a better way? ------- Re: Cutting threads Posted by: "greg" gregx~xxgelhar.com greg.gelhar Date: Wed Feb 24, 2016 2:17 pm ((PST)) You can use the compound slide to "pick up" the existing thread. Simply dial the cutting tool to match the threaded part. Greg G. Osseo, MN ------- Re: Cutting threads Posted by: "Jon Elson" elsonx~xxpico-systems.com jmelson2 Date: Wed Feb 24, 2016 6:48 pm ((PST)) Put the compound parallel to the main bed way. Engage the threading gears, and turn the lathe over by hand until the carriage starts to move. Bring the threading tool toward the existing thread using the cross feed until it is close to the major diameter, then adjust the compound until the point is centered in the thread. Advance the cross feed a bit, and adjust until the tool is all the way down into the thread. This will allow you to pick up and continue the thread with minimal error. Jon ------- Re: Cutting threads Posted by: "Art Eckstein" art.ecksteinx~xxgmail.com axtein Date: Wed Feb 24, 2016 2:31 pm ((PST)) The way I have "picked up the thread" on a shaft is as follows (and it has worked quite well for me): 1. Chuck the piece up in the lathe with it sticking out far enough to do what you want. (Of course if using a 4 jaw, indicate it true and use a live center in the tailstock if possible.) 2. Run the saddle out past the end of the stock. 3. After setting up for the proper thread in the change gears/qcgb, make sure the tool is clear of the shaft. 4. Turn on the spindle and engage the leadscrew. As you have indicated a 13TPI, you will have to use only 1 number on the thread dial. We will use #1 for the example. 5. When the thread dial comes to 1, engage the halfnut and allow the carriage to move over the threads (I use a point somewhere near the middle of the thread). 6. Stop the spindle. 7. Now jockey both the cross feed and the compound (assuming it is set at the proper angle) until the tip of the cutting tool is aligned with the thread. 8. When you're satisfied that you have it centrally located, set the cross slide to zero location or set your stop. 9. Back off your compound as it is now at full depth of your thread. 10. Open the half nuts and move the saddle clear. You can now test your location in the usual manner, but don't set the compound too deep till you're satisfied that you are right. If your testing shows good, you can now cut your thread as normal. Art Country Bubba ------- Re: Cutting threads Posted by: "brokenwrench1 ." brokenwrenchx~xxgmail.com brokewrench Date: Wed Feb 24, 2016 3:13 pm ((PST)) Yes set your compound to the correct angle with a good vee point cutter. Put the point of your cutter to just touch the unthreaded area of the stock and zero the crossfeed and compound feed dials. Move the carriage to the threaded area off the work. Align the thread dial to number 1 closest to the center of a thread. Move the cross feed and compound feed until the vee cutter is centered and bottoms in the root of the thread and note the distance of travel to obtain your root depth. This will tell you how many thousands to make your max depth of cut -- unless you have a thread mic. Now back out your crossfeed to the 0 point of the stock diameter and back the compound feed 0.001 back away from the headstock for every 0.025 cut you make in no more than 0.002-0.005 per cut you make depending upon the hardness of the work. This is done to prevent the tailstock side of the cutter from cutting the back side of the threads of the work. Set your spindle speed to the slowest gearing and i adjust the drive belt on the loose side -- just tight enough to prevent slippage in a cut this way. If you have a wreck, your drive belt will slip and not break your cutter or spin the work in the chuck. You might want to center drill the stock and support it with a live or dead center while cutting the threads. If you spin the work in the chuck or drive dog you will have to realign everything all over again to a thread dial number. When I was working in the shop I had to make several long lead screws on lathes that were too short to do the job and had to use both a steady rest and follower rest to support the work piece correctly when the lathe bed was too short. It is a good practice to have a thin 1" - 13 tpi nut screwed on the original thread area to test the fit as you get close to correct depth. I have used this method to cut threads on a 10 ft long piece of bar stock most of its length on a 12 x 36 lathe. I hope this helps ------- ------------------------------------------------------------------ This is just one of some 80 files about machining and metalworking and useful workshop subjects that can be read at: http://www.janellestudio.com/metal/index.html ------------------------------------------------------------------