Re: [CAD_CAM_EDM_DRO] tighten my ball screws

> My old CNC mill, Excello - bridgeport type, needs some attention to reducing
> backlash in the ball screws. What can be done to reduce backlash, short of
> replacing them?

See if you can adjust the spacing between the pairs of nuts on each screw.

> I'm tempted to try taking apart the ball assembly and cleaning and
> tightening. Will the whole thing fall apart,leaving me with a pile of ball
> bearings?

Yes, it will. Get an old blanket and put it on the floor. Sit in the
middle of it and work there so anything you drop won't bounce and
won't get far. When you take the nut off the screw all the balls will
fall out unless you feed a keeper tube in to hold them. Repacking
them is not that hard - probably takes about a half hour to figure out
a workable method and then 10 minutes to do. Grease can help hold
them in place if need be.

While you have the balls out you can mike them and buy some new ones.
Rarely you will see a nut with two different sized balls. If so, be
sure to get both sizes... and when you put them in, use the relative
numbers of each kind to figure out the proper pattern. Incidentally,
the tech guy I talked to at the nook factory said that the number of
balls isn't critical - plus or minus one or two per nut.

Alternatively, you would probably flush the nut out with some sort of
solvent and light oil (kerosene?) while it was still assembled. Be
sure to relube with something heavier afterwards.

> Or, are there places to send ball screws out for rebuild?

Yes, there are. Or I think you can just buy a new assembly if it
is compatible with bridgeport parts.

Chris