Ballnuts: Do you really need all the balls?

[geohot]

I was trying to reload a ballnut and couldn't get all the balls to stay in place. I tried just putting the ballnut back on the ballscrew without having all the balls. It seems to spin nicely with no backlash. How important is it to make sure all the balls get back in?

[HuFlungDung]

A little dab of grease would not help you with the problem? What kind of nut is it, one with external ball return tubes, or internal ball return circuit?

The more balls that the screw has, the better it will be for its wear life. This is because the unit pressure per ball should theoretically be lower if more are sharing the load. Think too, of what might happen if the screw experiences a shock load through a crash: more balls may help resist damage to the screw through dimpling.

[geohot]

It has internal ball return tubes. In the time since I made this post I came up with an idea. I put Neodymium magnets all around the ballnut. The balls were much easier to get back in.

[harlan]

I just reloaded two ballnuts, i've got it down to ~20 minutes each at this point. I've had them together and apart a few times though.

Internal returns, 4 circuits, 92 balls each nut. A little tub of bearing grease and a short piece of .035 TIG rod was all I needed. Just don't be bashful with the grease.