This file has many users' tips for cutting threads. 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. 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 more than 70 additional files on my home page Machining and Metalworking at Home http://www.janellestudio.com/metal/ 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 - 2012 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 "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 Ģ2.21 and the dies Ģ4.89 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 ------- 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. ------- 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 ------- [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: 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 didnīt 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 an