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 - 2008 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