Centroid Community CNC Support Forum

Hi, I am trying to calibrate my cnc lathe. I have been using the turns per revolution calculator from this forum. However I am getting some odd results. My stepper drivers are set to 5000 steps per revolution. My bullscrew is direct drive and it takes 6.25 turns for 25mm. I started with a small movement command. G0 z5 f1, the machine moved 24mm. I input the calculation into the calculator and input the results into c12. Switched off both c12 and the acorn board. Restarted both. Input the same command again, but nothing has changed. What am I doing wrong?

How are you inputting this new value, through the wizard?
You're sure to hit the "Write settings to CNC control configuration" button after changing the value?

Yes through the wizard. And I do hit write settings before closing. The green bar shows up etc.

metric or imperial setting on your machine?

What kind of steppers? 5000 steps are unusual.

Pls post a report.

Uwe

And a 5.5mm pitch ballscrew is also suspect, as would be a 5.6TPI ballscrew.

tblough wrote: ↑Fri Aug 22, 2025 12:13 pm And a 5.5mm pitch ballscrew is also suspect, as would be a 5.6TPI ballscrew.

25/6.25=4mm pitch

Uwe

You are correct Uwe. I must be getting senile.