A few problems with cnc lathe.

[terry1956]

Hi, I have been trying without much luck to calibrate the axis on my cnc lathe. I am running mach3 which does not have the auto calibration as the milling program.
Know matter how many steps per rotation I input I just can’t get the axis to move the correct distance. If I push the steps too high I find that the axis starts to move in the wrong direction which i is coursed by the torque in the motor.
I started at a rate of 800 steps pre revolution and then 1200 and going up by 400 steps ended at 16000 which must be wrong.
Can anyone help out here. And also is there a lathe cnc program that will calibrate the machine without all this fooling around.
Thanks.

[m_c]

Just calculate it.
What pitch are your ball/lead screws?
Are the motors direct drive?
What microstepping are you using? (I'm assuming that you're running stepper motors)

[terry1956]

Hi, I have calculated it. I made it 1000 steps per revolution. But that does not work.
The lead screws work out at 14 turns per inch. The drive is belt at 1 revolution of the motor to 1 1/4 turns of the screw. At the moment I am using 1/4 step.
It’s all very odd.

[Muzzer]

What's the machine?

Are you planning to work in imperial units?

What controller and driver and motor are you using?

What is the maximum pulse rate for the stepper driver?

Helpful if you give us a few clues, although I appreciate it's Xmas quiz season.

[JohnHaine]

14 tpi is a funny pitch for a leadscrew, 0.125 or 0.1 inch would be more common. What sort of lathe is it?

Anyway 1 motor turn moves the carriage 1.25/14 = 5/56 inches. You want to calculate the steps per unit, or steps per inch. You need 56/5 turns to move 1 inch, so (800 steps/rev) x 56/5 = 8960 I think.