RE: [CAD_CAM_EDM_DRO] Ball screw/nut repair

There are two places where you get play in a ball screw assembly, the ball
screw itself, or the end thrust bearings.

The whole thing professionally overhauled is going to eat money.

I would pull it apart and have a look first. The end thrust races will be
easy to change, and reasonably priced, they may just need tightening.

8 thou backlash is a lot, I would expect a ball screw to be jamming long
before it gets this bad, and be extremely noisy and chewed up, but a loose
thrust race could easily be this bad.

So hopefully it’s just a little bit of thrust race work. If the ball race is
suffering, you can have them reground and use oversize balls, but the
grinding job is expensive.

Most ball screws have less than ½ thou play, worn ones a bit more but not 8.
If the groove is in good nik you might be able to fit oversize balls, you
can get these cheap on ebay.



A good method to see if it’s the ball screw is to look at the backlash in
the middle and at the ends. If it’s the thrust race, you will have the same
backlash, if it’s the ball nut you will probably have less at the ends.



Just some thoughts before you hand that hard earned cash over.



Dr. Mark Vaughan Ph'D. B.Eng. M0VAU

Managing Director

Vaughan Industries Ltd, reg in UK no 2561068

Water Care Technology Ltd, reg in UK no 4129351

Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
Phone/Fax 44 1872 561288

_____

From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Vince Endter
Sent: 04 February 2007 19:16
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Ball screw/nut repair



I was able to get my Yamazen mill up and running and check the
backlash. Both the Z and X are less than 0.001. The Y is 0.008. I
checked the Y ball screw and I can feel a "crunching" when I rotate it
back and for. It looks like I need to get it overhauled. Does anyone
know of a place (Northern California would be prefered) that I can get
a ballscrew overhauled?

Thanks

Vince





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