I think there are two things to look at if you tell Mach3 to move a certain distance and Mach3 reports that it moved the correct distance but does NOT move the correct distance.
1. Calibration. There is a calibration process where you tell Mach3 how many steps per Inch (probably MM or CM if metric).
a) If your error is consistent under zero load moves, this is likely a good way to fix the issue
b) there is a routine in Mach3 that will help you calibrate, or you can do some controlled moves, entering the step value manually
2. The stepper is missing steps. In other words, Mach3 tells the stepper controller to move a certain number of steps but the stepper does not.
a) A few things come to mind that might cause this:
- Acceleration is set to high and stepper can't keep up (set acceleration very low for testing to see if this helps)
- Load to high for stepper, Gibs set to tight, Stepper defective, Too small of a stepper for the job, Other mechanical problems causing high load