Engraving small font - the bit digs deeper and deeper as the job goes on. 6040z

[lucan07]

OK so I mixed up the poster of one part of thread it does not change the point that whatever is moving 3.75mm should be easily identifiable, if the ball screw is dropping the retaining nut on base would be 3.75mm below expected position and obvious. this is obviously a poor design the retaining of ballscrew appears to be on wrong end but unless ballscrew dropping 3.75mm an easily visible amount another fault is likely to be the problem.