Cnc 3040 z ball screw

[routercnc]

Ok that's better. The first picture was of the supported bearing end not the nut - now we can see the ballnut it is a standard Chinese type.

Ballscrew is most likely 12mm and the pitch looks like you have measured between a peak and a trough. Needs to be between 2 peaks OR 2 troughs so it is most likely 5mm. So you have a 1205 ballscrew and nut.

You can try to buy just a new nut but they come as a matched pair with the ballscrew and the ball bearings are sized to be a good fit. That means another random nut may be too tight or too loose on your ballscrew. Unless you have a tuning set of ball bearings your best bet is to strip the nut down, clean it, grease it and reassemble with missing ball bearing in. Chances are it was clogged up inside and jammed the return channel. Have you ever greased the nut?

When you remove the nut watch out for the remaining balls which will fall out. You will also need a guide tube to sit over the floating end of the ballscrew to guide the nut off and back on again. Once inside the nut look for damage to the plastic returns.

The are videos on YouTube about repacking ballnuts