Lead screw or thread dial not right?

I looked it up, Eisen does say 4 TPI for the leadscrew. Also saw in the pics that the thread dial chart is on the front of the thread dial itself. Regardless, for 24 TPI you should be able to engage the half nuts anywhere, no thread dial needed.

The only other thing I can think of is if you are threading using the modified flank method, as in using the compound slide to advance cuts. Typically you would set the compount to just under 30°. Usually on asian lathes, with the compound parallel to the spindle axis, the protractor reads 0. So in order to set the compound to 29.5° or whatever for threading, on your lathe's protractor you would need to set it to 60.5° & NOT 29.5°. This commonly happens. Not sure if that's what's going on in your case but I can't think of anything else right now.

mg9520_f67ec4f4-e574-46c9-80ba-91633f4cf138_grande.jpeg.jpg
Compound_Thread_Angle.jpg
 
Wow, that’s coarse.
Regardless shouldn’t make any difference on an even pitch thread. Something else is going on.
 
Did you check the pitch of the threads on the work piece with a thread gauge? Sounds like you may have the wrong change gears installed. Perhaps, for Metric threading? Usually, cutting even number english threads, you can engage the half-nuts on any Division. My Hamilton lathe has a 4 tpi lead screw and works this way.
 
4 tpi is pretty big.
Have you actually measured the threads to see what pitch they are?
Whatever you find, one way that is failsafe is to use the same # on the dial every time.
 
No idea, unless you're not actually set for 24 TPI. If it was say 28 TPI I would say check to see if the thread dial gear is loose. It happens & on some lathes that gear is not keyed. But if you're set for 24 TPI should be able to engage anywhere.

What method are you using for advancing DOC? Cross slide or compound slide?
Advancing on the compound
 
I looked it up, Eisen does say 4 TPI for the leadscrew. Also saw in the pics that the thread dial chart is on the front of the thread dial itself. Regardless, for 24 TPI you should be able to engage the half nuts anywhere, no thread dial needed.

The only other thing I can think of is if you are threading using the modified flank method, as in using the compound slide to advance cuts. Typically you would set the compount to just under 30°. Usually on asian lathes, with the compound parallel to the spindle axis, the protractor reads 0. So in order to set the compound to 29.5° or whatever for threading, on your lathe's protractor you would need to set it to 60.5° & NOT 29.5°. This commonly happens. Not sure if that's what's going on in your case but I can't think of anything else right now.

View attachment 450085
View attachment 450086
I do have it set to 60.5 - I used an angle gauge to verify the compound was 29.5 and made a mark on my cross slide. 60 is not marked on my lathe.
 
You installed a new leadscrew after your lathe got damaged. Is it possible the new part is metric leadscrew?
I guess it’s possible - it does cut a 24tpi if I stay on one number…
 
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