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well with no quick-change gears and no thread dial, it really doesn't matter what the minimum spindle speed is, threading is going to be very difficult at best.
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What is the minimum spindle speed when the machine is set up for thread cutting? The machine specs have minimum spindle speed at 80 rpm, but I seem to recall seeing something as low as in the mid 30's listed for threading.
80 is a little fast, but I can live with it.
well with no quick-change gears and no thread dial, it really doesn't matter what the minimum spindle speed is, threading is going to be very difficult at best.
Yeah, after threading with my 3in1, that is one of the reasons I got the leblond, quick change gearbox, half nuts, lowest spindle speed 25 rpm,and thread dial.
But before that I have done some threading on my 3in1.
Changing gears to set up the lathe for threading or feed is a little time consuming.
No half nuts or thread dial, you can just reverse the spindle at the end of the thread after backing out the tool.
Just need to practice backing the tool out at the right time
threading to a shoulder at 80 rpm at 5 TPI would really tax your reflexes.
Maybe stop the spindle and cut the last couple threads by turning the chuck by hand
Should be easy to come up with a speed reducer. Maybe a three phase motor and vfd.
Like Norvil says, threading on a 3in1 without the threading capabilities of a real lathe will be difficult at best, but with any lathe, the more threading you do the better you get.
Wasn't somebody working on an electronic leadscrew. That would be the ticket.
You will find ways to overcome the limitations.
Good Luck
Flathead
Most of my threading will be for rebarreling Mauser actions for custom rifles. I usually run at 45 rpm on a dedicated lathe. One shoptask owner builds target rifles with an older machine. Apparently, his rifles do well enough for 1000 yard competition.
It is nice to just change gears on a dedicated lathe, but I have the time. I'll do several practice runs on round stock to become familiar with the controls before I run a real barrel.
I found the info on thread cutting speed. The Patriot comes with a low speed set up to allow a speed of 31 rpm for thread cutting. That is slower than I am accustomed to using. That gives me about 13 seconds per cut on a barrel.
Roadster
If the patriot goes down to 31 rpm that will work.
After you get the threading procedure down and some practice you'll be able to increase the spindle speed and probably get a better looking thread and cut down the machining time too.
Flathead
Roadster,Originally Posted by Roadster
80 rpm is the minimum on the Patriot. The older machines had an oprion for 31 rpm, but because of the design change, it does not fit the Patriot model.
80 is workable once you get the hang of it- its sort of " old school" in that you must start your carriage on the same spot each time- easy with DRO and also start each pass in the same rotational position of the spindle- the spindle indexer does that for you.
I saw the ST12 low speed option online as being standard on machines made after 1996. I guess Taylor needs to change that to exclude the Patriot.
80 rpm will give me 5.6 seconds per pass on a mauser barrel shank .629 inches long. That is roughly 5 seconds plus reaction time to disengage the feed at the relief cut. That should be enough.
Except for the power feed that part hasn't changed. There a small gear box with 2 RH helical gears for the hand feed on the X axis added that's all. the spindle housings has been the same since 1990 except for a few changes but the old ones will work if modified. Which can be done with a reamer to fit the needle bearings. Also the shaft needs to be turned down. So I don't see any difference with the gearing or any reason to change it due to other design changes.
If the speed can still be cut to 31 rpm for threading short distances, it will help.
the spindle bore is a mt3 , no cathead on rear of spindle so threading a metric thread to a shoulder with no relief cut and no thread dial and no half nut a on bull barrel is going to be interesting. just out of curiosity what is major diameter on Mauser receiver threads?
Norvil the spindle bore is a MT4 . The tail stock is a MT3.
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