So I have a very frustrating problem that won't go away. I have set up a mill with ugs and grbl. I have fine tuned the steps per mm to go 'exactly' one inch when I program a 1 inch move. It works perfectly when I move one inch. But when I program a .01 inch move it falls short by .008" and when I program a 2 inch move it overshoots by .008". You can see how this is not a backlash issue. Backlash does not make moves longer it makes them shorter. I then calibrated with a 10 inch move and got the same results only proportionally larger deviations. When I move less than the calibrated distance my move falls short and when I move longer than the calibrated distance my move is longer. My moves are only accurate when I move the calibrated distance. Having eliminated backlash or mechanical issues such as binding lead screws or loose mechanical connections I wonder if anyone else has had this problem of faulty scaling. when I searched your forum for 'grbl scaling issues' I did find one guy named jeffxclark who reported the exact same problem but the thread ended with no solution. any suggestions except to check for backlash of course would be appreciated.
