Hi Graham
Thanks for your reply.
Pitch is 2mm, 4 starts, and you are correct when you say motors are driving the lead screws directly. I'm not sure what you mean by stepping though.
Mach 3 units are set to mm in the 'set native units' drop down and set to mm in the settings tab, this is confirmed by Mach 3 displaying G21 in the top right of the screen. Files are created in Vcarve and are set to mm, and saved to the mm option in the post processor save dialogue, and have G21 at the start of the G code .txt file.
This issue I have is not steps per unit; I set that empirically for the X and Y (the drives that I have changed) and Z has always been on a 2mm pitch, 4 start lead screw with 5120 steps per unit. I set X and Y to this and have made adjustments using the 'axis calibration' option in the settings tab. The issue I have is that now it only moves in inches, even the Z-axis which I haven't changed, only fine tuned with the 'axis calibration' option.
The only thing I am doing differently is that I have been using the MDI page when testing X Y movement. I have found that MDI only seems to work in inches, regardless of settings. i.e. with everything set to mm, an input of X1 in MDI caused a movement of 25.4mm, not 1mm as expected.
On the advice of newfangled solutions, I uninstalled/reinstalled Mach 3, but the issue remains.
Any suggestions?
Regards
Peter