I've been investigating where my backlash of 0.07MM in the X axis has come from. I took the table off to check the ballnut mounting block and one thing I noticed is that if you move the end of the ballscrew you can see the back end of the ballnut (with the orange caps in) move. The front is solidily located in the block.
Is this normal? Are these ballnuts actually anti-backlash? I would've thought the pressure between opposing ball nuts would take a bit more than slight pressure on the screw to move in some way.
Last edited by iGG1e; 05-13-2009 at 04:19 PM.
Only one end of the ball nut is fastened to the frame. The other end is only held in place by two locking tabs and the ball screw. The floating nut is rotated toward the other nut and locked by the tabs. This sets the near zero backlash. If the backlash is too great, it might be possible to insert a .001 or .002 shim between the two nuts to decrease the clearance. I haven't tried this so can't verify it.
What ever you do, don't run the nut off the end of the screw or you will have a handfull of balls. I can verify that it isn't fun to get everything back where it belongs.