Re: [CAD_CAM_EDM_DRO] Help! Ball Nut Catastrophe

gjameson1 wrote:

> Well, my curiosity got the best of me. I was cleaning a greasy,
> rusty linear lide with a nice ball screw and nut and decided the nut
> needed cleaning also (it nor the screw is rusted, i was just trying
> to remove old grease). i have never worked with ball screws and did
> not know that the ball were ready to jump out at me when i removed
> it. i scratched my head, cleaned the nut and all the balls and
> figured it couldn't be that hard to get them back in there properly.
> After about the 10 disassembly/reassembly i have resorted to this
> global request for help. the problem is that when i reassemble and
> put all of the balls in the nut and some in the tube that runs
> diagonally along the outside of the nut and fasten it in place and
> grease it, the nut spins freely a few turns then binds. some of the
> balls will even escape the nut through the felt wiper. the screw is
> parallel with the travel of the slide also. before i ever removed
> the nut from the screw the motion was flawless. is there some secret
> to this or have i cost myself serious dollars. surely getting the
> balls to run the internal race correctly isn't impossible. please
> help.

There are two ways to reload a ball nut. If you can remove the
recirculating tube, put the screw in the nut and start feeding balls
into the hole where the tube went. Turn the screw into the nut to
feed the balls into the track until they start to come out.

If it is a preloaded nut with two tracks, count the balls and put half
in each track. If you put too many balls in a track, it can bind up
and damage the screw and nut.

The other way is to make a mandrel which has the same minor diameter
as the ball track. Separate nuts are usually sold with a cardboard
tube of just the right diameter for this purpose. You screw the screw
into the nut while holding the mandrel against the end of the screw
so the balls can't escape. For loading, it is a LOT easier to see
what is going on, and you can drop balls in while slowly advancing the
mandrel to keep the ones already in the track from escaping.

Jon