the mystery of the wonky corners

[Jonathan]

Intereting...

By 'meant to be square', do you mean it's meant to be a square, or that the corners are supposed to be sharp? If its meant to be cutting squares and you get that, then at least part of the problem is the step/mm value in the motor tuning settings has changed...so check those. On your machine it should be the same number on X and Y and two times that number on Z.

Is the machine loosing position, i.e. does it return to (0,0) when finished? If you suspect it might be a motor stalling, then run the program I made here:

http://www.mycncuk.com/forums/gcode/...or-tuning.html

If it survives that test without stalling it'll survive pretty much anything, so I'd do it anyway as you've changed the motor settings.

Does it look correct in the tollpath preview in Mach3? Zoom in on the corners...
If you run the program again does it follow the same path?