I have a very confusing situation with my Shapeoko2. The x-axis exhibits backlash (travels 0.007" short when reversing direction) on moves greater than about .08". The y-axis is backlash free (~0.001"), and the x-axis is fine on moves less than that. Both axes move predictably when each increment is in the same direction.
I have tried reducing the acceleration max and max speed but nothing helps other than smaller moves. All hardware is tight and the belt is properly tensioned. Are there any other settings on the gshield that could affect this? The step pulse time is 10 us which is 10x the minimum per the driver spec sheet. As I said, the motion is correct when each move is in the same direction so I have no indication of thermal shutdown etc. I've used a dial indicator to try to detect any flexing in the gantry but nothing is apparent.