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Using lathe to cut threads

Glen Linscheid #5924 For many years I used to take a scratch run on the part and check it with a thread pitch gage, the DRO method (In this case the dial indicator method, but not a dial test indicator) works as well and leaves no scratch marks, which wouldn't show anyway I guess. toggle quoted message Show quoted text On Mon, Aug 1, 2022 at 5:13 PM Joseph Difusco via <josephdfco=[email protected]> wrote: Thanks, Glen !? I'll give that a try and report back with my findings.
Joseph Difusco All Messages By This Member #5923 Thanks, Glen !? I'll give that a try and report back with my findings.
Joseph Difusco All Messages By This Member #5922 Sorry for the misunderstanding, DW.
Glen Linscheid #5921 The last time I tried to set up the old style gearing I gave up without a struggle, just because a feed box makes it so easy that it's part of my understanding of the lathe. One of the questions I stumbled on was the term "stud" and not knowing which position it meant, however, you only have three opportunities, two of which are wrong, so it should still be easy, just don't choose a thread that needs compound gearing to make it work until you make your discovery (I think compound gears go on the stud if I'm not wrong, Haven't looked at a selection plate in a while). To test your setup engage the half nuts and make a mark on your chuck with a felt pen and an opposing mark on the headstock so they line up. (Leave the power off for this) divide one inch by the number of treads per inch, in this case it would be .050". Set a dial indicator to show the movement of the carraige at zero and pull the chuck over by hand exactly one revolution, the indicator should read .050" if you have it right. Much easier with a DRO.
john rosberg #5920 开云体育 I ask because I’ve the same question! John Rosberg toggle quoted message Show quoted text On Aug 1, 2022, at 13:18, Joseph Difusco via groups.io <josephdfco@...> wrote: ?Hi John! No, not yet. I just need to know exactly which gear is which on the gears, as listed on the back plate. Thanks!
dwshelf #5919 I'm backing out, intended no snark.
Joseph Difusco All Messages By This Member #5918 Hi John! No, not yet. I just need to know exactly which gear is which on the gears, as listed on the back plate. Thanks!
Joseph Difusco All Messages By This Member #5917 I'm a certified machinist, but it's been about 6 years, and several hospitalizations at the VA, since I've done anything in my machine shop.? I'm not asking how to cut threads, just how to cut them manually with a machine like the Dalton, and at this point, the only info I need is which gear goes where as labeled on the back cover.? I'm cutting the inside of two1.5" OD tubes, 20 tpi NS, and the outside of a 3/4" OD tube, 28 NS.? I know how to cut threads on a modern lathe. I'm curious, DW: in the time it took to write that snarky, unhelpful reply, why you couldn't simply have answered my question about the gears, or let someone else help?
john rosberg #5916 开云体育 Did you ever get your stud gear question answered? John Rosberg toggle quoted message Show quoted text On Jul 31, 2022, at 22:11, Joseph Difusco via groups.io <josephdfco@...> wrote: ?Thank you, Glen! Yes, I'm all set, except for how to put on gears.? I just need to know which gear is the stud, which gear is the screw.? I'm doing a 20 tpi internal thread.?
Glen Linscheid #5915 ?So you still think you know what size he wants to make an internal thread in, or what hand? BTW, I only saw one 1 1/4 - 20 tap for $25.50 tap and with shipping it's $39.40, maybe he isn't rich enough to pay that for a one time ID thread, especially when he wants to learn how to become more savvy than hobby lathe users who never learn to thread with their lathes, we all started sometime. Besides all that we still don't know what size hole he does want to tap, or even if it's a common size. Above all that, he didn't ask where to buy a tap, he asked how to set up his lathe to cut threads.
dwshelf #5914 And if it's a size that no taps are made for what would he ask himself? Taps are almost always available. To use your example, there are at least a dozen online sources of 1 1/4-20 taps.
Glen Linscheid #5913 And if it's a size that no taps are made for what would he ask himself? toggle quoted message Show quoted text On Sun, Jul 31, 2022 at 8:46 PM dwshelf via <dwshelf=[email protected]> wrote: What I do know is that cutting decent, let alone precision internal? threads requires some skills which are well in advance of how to? select gears. I don't doubt those skills can be acquired by experience and mentoring, but I'll suggest again, during such a period of acquisition? it is predictable that one would contemplate the question of "why didn't I use a tap". Or even more likely, "maybe I should use a tap".
dwshelf #5912 What I do know is that cutting decent, let alone precision internal? threads requires some skills which are well in advance of how to? select gears. I don't doubt those skills can be acquired by experience and mentoring, but I'll suggest again, during such a period of acquisition? it is predictable that one would contemplate the question of "why didn't I use a tap". Or even more likely, "maybe I should use a tap".
Glen Linscheid #5911 ?I'm curious DW, how did you know what size hole he wanted to produce threads in? He may have been wanting to make an internal hole inside a telescope eyepiece mount, or to get higher quality centricity and alignment and fit in a muzzle break. There are special taps for sizes other than 1/4-20 or 1/2-20, but they are more expensive. toggle quoted message Show quoted text On Sun, Jul 31, 2022 at 8:16 PM dwshelf via <dwshelf=[email protected]> wrote: By the time you have succeeded, and I have no doubt that you will, you will have revisited the question of why you didn't use a tap.
Glen Linscheid #5910 I'm curious DW, how did you knew the internal diameter is small enough that a tap is made for it? If he's making a telescope eyepiece fitting it may be 1.25 X 20 TPI, but he didn't say, or, he may be wanting a 1/2 X 20 TPI hole in a muzzle brake for extreme accuracy and fit, I sure don't know.
dwshelf #5909 By the time you have succeeded, and I have no doubt that you will, you will have revisited the question of why you didn't use a tap.
Joseph Difusco All Messages By This Member #5908 Thank you, Glen! Yes, I'm all set, except for how to put on gears.? I just need to know which gear is the stud, which gear is the screw.? I'm doing a 20 tpi internal thread.?
Glen Linscheid #5907 Edited I apologize Joseph, when I saw your email last night searching for a youtube video that would cover it and found four that didn't cover them, and intended to continue however I was exhausted after two day work which I'm not used to and turned in early. What video did you find? ?Of course South Bend lathe's early book "How to run a lathe" made before they switched to gear feed selector types should have a great deal of information, and myself, after a lifetime past my first lathe which did use pick off gears, I've forgotten all of it and recently thought about this because I own several older lathes which I keep for display and historical purposes. ?I'm glad you found the info! Glen Linscheid
Joseph Difusco All Messages By This Member #5906 Nevermind, guys; I just watched a video explaining how to do the marks on the chuck, screw, and bed.? I still need help with what gears go where please.? Thanks!
Joseph Difusco All Messages By This Member #5905 BTW, I'm cutting 20 TPI threads inside of a tube.? I'll be using a steady rest, after turning a shallow bearing surface for it.

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