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

[sinnsvak]

I assume I have the same machine, and this is where the ballscrew is fixed.

Atleast on my machine, no motor-coupling would have anything to do with it.

[cropwell]

Yes, we really need to see what is going on at the lower end of the Z on the OP's machine

[xoneeleven]

Hello All,
Here are some photos of the bottom of the screw, the mid point, and another of the upper section per your request.

Thanks again for these tips and info.

[cropwell]

Check the bottom bearing is not loose in the plate. It just looks like a push fit and it could have gone sloppy.

[magicniner]

In the photo in post #4 there's a gap between the red buffer and the driven section of the coupling, either the ballscrew moved down or the driven section of the coupling moved down.
If the driven section of the coupling can move down then it's not tight enough and would also slip in rotation, and because more torque is required to lift Z than lower it the axis would slowly slip down.
If the coupling driven plate is slipping then stripping, cleaning, then reassembling with a stud & bearing fit compound may provide a temporary fix,

- Nick

[lucan07]

I cannot see this being the problem more likely the simple options, ER11 thread damaged and not locking collet properly, material insufficiently secured if clamped at edges acrylic will lift in centre with any sort of up cut helix, wrong collett size used, whatever is causing a 3.75mm shift is gong to be measurable so measure collet protrution, relative position of ballscrew, deflection in frame or material plane with dial indicator etc and identify movement.
Before trying to remedy a problem identify it and save a lot of unecessary speculation.

[magicniner]

I cannot see this being the problem more likely the simple options, ER11 thread damaged and not locking collet properly, .

Could you speculate on how this would cause the bottom section of the Z axis motor coupling to move into contact with the screw underneath, leaving a gap in the coupling assembly which should not be there it as can be seen in the video?
:D