Help – I Just Spun the Nut off the Ball Screw Shaft !

Routinely we get a phone call at least once a week – “hello – help – I have a Steinmeyer ball screw and I just spun the nut a bit too far at the shaft end by mistake and now I have some loose balls – what do I need to do?”The short answer is “make sure you never do that again”!  The more useful answer is – “return all pieces to Steinmeyer” so we can inspect and repair it.  And yes that means returning the product to our factory in Germany.  Could you get it repaired domestically?  Yes, but chances are it will not be repaired to exactly the same state as when it was new.  The reason?  When we assemble ball screws, the match between ball nut and shaft is within a few microns!  This means we choose the correct size balls to install inside the nut to achieve the correct axial play, including zero.  And the balls we use are metric, matched to within one micron.  Domestic repair facilities typically use the nearest inch equivalent – and hope for the best.  BTW, we also have seen instances where someone inadvertently spun the nut too far, a few balls came out, and the person tried to re-insert the balls – but to his/her dismay the nut no longer moves as smoothly as before.  The reason?  Unless you have the proper tools and are able to re-insert balls into their proper location inside the nut, just “stuffing” balls back inside results in the balls being in the wrong location (outside the ball deflector path).  Then when the nut is moved on the shaft these balls end up skidding, not rolling.  So take a tip from us – be safe and return the parts to the original source.  Now this piece of advice presumes that you are the OEM who installs the ball screw in the first place.  If not – then you need to contact the machine builder and not us directly – more on that in another blog.

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