Quote Originally Posted by Gary View Post
Out of interest what are the flats for? Are you fixing the ball screw and turning the nut?
Also 0.25mm is going to be very sloppy on the bearing and may cause you problems?

The flats are for the grub screws that lock the pulleys and handles in place. The nuts hold tension against belleville washers I wouldn't want to rely on them to grip anything.

The tolerance does not apply to the shaft diameter, that wants to be a nice sliding fit. I'm sure you can do better than .25mm anyway.