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Using lathe to cut threads
Hi guys!? I was hoping somebody could help refresh my memory.? I have a machine shop in my basement, and life has gotten in the way of me enjoying it for the past few years.? I have a Dalton Six B-4, and I'm getting ready to cut some threads with it.? I've completely forgotten the procedures, like marking the chuck and way, manually withdrawing the carriage, etc, and which gear is the stud.? Is it the one that sits below the two little gears that are directly below the spindle, or adjacent to the screw on the same bracket?? I'm guessing that the screw (as marked on the plate that covers the gears) is just that; the one attached to the screw that moves the carriage.? If you could walk me through the whole procedure like it's my first time,? I'd greatly appreciate it.? Thank you!
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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 |
Glen Linscheid
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.
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Glen Linscheid
?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. On Sun, Jul 31, 2022 at 8:16 PM dwshelf via <dwshelf=[email protected]> wrote:
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dwshelf
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
And if it's a size that no taps are made for what would he ask himself? On Sun, Jul 31, 2022 at 8:46 PM dwshelf via <dwshelf=[email protected]> wrote:
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Glen Linscheid
?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. |
john rosberg
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On Jul 31, 2022, at 22:11, Joseph Difusco via groups.io <josephdfco@...> wrote:
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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?
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john rosberg
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On Aug 1, 2022, at 13:18, Joseph Difusco via groups.io <josephdfco@...> wrote:
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Glen Linscheid
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. |
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