There are companies that regrind and reball ballscrews. One I looked into
claimed they could grind rolled ballscrews to be as precise as ground screws.
Some ballscrews have every other ball undersized to further reduce friction,
but it also reduces load capacity. Replacing the spacer balls with full size
ones, removing one or more from the total to make room, increases the load
capacity and may improve precision or lower backlash.
Putting in oversize balls won't work with very uneven wear on the screw. It
could jam on the unworn areas. At best if the screw has some wear all along you
could oversize to be as tight as possible on the least worn area and have some
reduction in lash elsewhere.
On Wednesday, April 14, 2021, 7:48:12 AM MDT, Chris Albertson
<albertson.ch...@gmail.com> wrote:
I have no experience with this but I've read about people using oversized
balls to fix this. I think it is a stop-gap. But you can see how they
would ride above the center of the groove and be very solid. They are
talking *very tiny* amount of oversize. I seem to remember having to
sort the balls using a micrometer.
On Mon, Apr 12, 2021 at 8:14 PM Stuart Stevenson <stus...@gmail.com> wrote:
> Plus or minus .010 is an amazing amount. Also, you mentioned another area
> on the screw you saw .001 lost motion. This leads to a screw problem.
> I would do what Jon Elson says as this sounds strange but I would expect to
> find screw wear. If it was nut wear the backlash in all areas of the screw
> would be close to equal. Not knowing the drive train maybe there is a gear
> train and one area of the gear train has worn teeth and where you found
> almost no lost motion is where the gear train is the best.
> Expect screw wear but hope for a gear train problem.
> HTH
> Stuart
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