Originally Posted by
dharmic
You're losing steps.
Forgive me if this is overexplaining, but just in case...
Mach3 sends your stepper drivers step+direction signals. One wire is powered or not depending on clockwise or anticlockwise (direction). The other gets a pulse each time Mach3 wants the stepper to move one step in that direction. Every time it sends a step, Mach3 increments or decrements a counter for that axis. The DRO shows the counter, scaled according to your steps per unit in the motor setup, added to whatever the fixture/work offset is on that axis.
Point being: if Mach3 sends a step and the stepper doesn't for some reason, Mach3 doesn't know or care - it'll happily up the DRO.
Losing steps on one axis is going to be caused either by
- a programming issue (your feed rate is too high for the steppers on some part of the job, or you're maybe doing a small rapid whilst still engaged with the workpiece);
- a configuration issue (in particular look at the acceleration settings on the motors. You should be able to put your hand on the top of the spindle and apply a little braking whilst doing a jog from side to side without it skipping).
- a mechanical issue (if there's any tight spots or debris on the X screw or rails it can cause skipping).
Based on the litany of niggles you seem to be having, it might be worth considering abandoning carving all manner of pretty for a while and instead grabbing some stock, learning some basic G and M-codes (in particular G00, G01, G90/91, G3 and G5 with their associated parameters eg S and F) and using the MDI interface in Mach3 to do some systematic testing of loading it up in each axis and seeing where things are going wrong. Just a slightly more systematic approach, trying one thing at a time, is going to highlight issues faster than running a full job and getting to this fairly unhelpful (to you) point of "something went wrong but I've no idea of what actually caused it)".