LOL on the dizzy thing. But thank you for adding the video and drawing or the Z, that makes sense now.
If you want to get a rough measurement of a ball screw, can you measure the one on your Z? I should be able to figure out the others.
Would it be better to have all the motors on a belt drive setup?
I was wondering what that cap screw was for, that's a good idea for a bearing retainer.