Threading on Sherline lathe

And the second part of the question?

Not sure if it is able to do 4 tpi. For what I am doing I have to have 40 tpi internally and externally. I tried threading again, and I set the spindle speed at roughly 1000 rpm. The tool engaged engaged the part at the same speed it jogged to the part from the home position. It simply is not synching up to spindle.

Boltonbrass wrote: Not sure if it is able to do 4 tpi. For what I am doing I have to have 40 tpi internally and externally. I tried threading again, and I set the spindle speed at roughly 1000 rpm. The tool engaged engaged the part at the same speed it jogged to the part from the home position. It simply is not synching up to spindle.

Max velocity in the INI file is 0.475 in/sec.

40 tpi @ 1000 rpm = 0.417 in/sec.

So the machine should be able to do 40 tpi @ 1000 rpm. How accurate is your spindle speed? It would not have to be much faster than commanded for the system to be unable to keep up.

It might be that the Z-axis can never actually "catch" the commanded position.

Andy, I have just successfully made 40tpi work. Thanks for all the help. My problem was trying to use g76 instead of g33. So basically I was already there.
My slowest rpm is basically 1300 so I will have to change motors, so I believe I am good to go. You are a real trooper and I thank you for your help.

G76 should work. But your spindle speed will be a problem.
If you can't get more Z speed the other option is to turn the spindle by hand. LinuxCNC can still sync to a hand-cranked spindle.

I used a gear reduction attachment from Sherline and I made perfect threads this morning.
Thank you for the help. Next will be to get the 5i25 mess kit to work.