Well, I bought a pair of NSK bearings for the Z axis of my CNC mill, and removed the old ones and inserted the new ones. Cost $AUD 200. Plus 2 or 3 half days of dirty heavy work. And the problem persisted!!@!@
OK. Time to get an expert opinion. Here comes the cavalry. Thank goodness for my expert friend Stuart T.
Very puzzling. Even for Stuart. There was some unwanted movement in the Z axis (about 2mm), despite being apparently properly installed. Not a problem with the ballscrew or ballnut. Even Stuart was puzzled.
“have you got any left over bits and pieces? Is it all installed the way it was before?”
To cut the story short, we installed a thicker washer below the locknuts, and it seemed the problem was fixed. Or was it?
Today I did another test run of the bombard mouth Arabic script. Worked fine. OK. Time to finish the bombard.
The translation of the Arabic script is “Help O God the Sultan Mehmet Khan son of Murad. The work of Munir Ali in the month of Rejeb. In the year 868.”