On 4/12/21 9:48 AM, Todd Zuercher wrote:
Those here who have had to deal with a worn out ball screw. How is this normally manifested. I have a
machine that is only showing backlash under load. Is that normally how a worn out screw shows it's age?
I was expecting it to be normal loose backlash that you can measure. But this is showing up as springy
softness that you have to give a pretty hard shove against to move the dial indicator, then it snaps
back to zero when you let go. Using the usual jogging methods to read backlash, the machine reads zero
backlash and positions well. But dynamically it is awful, with loud clucking noises on direction
changes and horribly wavy marks left on the pieces milled at those changes. Giving a shove on the
table, I can measure more than +/-0.01" of this "springy" backlash, but moving the screw
to a normally unused position I can only measure about 0.001". This is a big fixed screw (about
2" diameter and more than 14ft long) with rotating nut, is there any hope of fixing it? I'm co
nsidering trying to send the screw out to one of those screw refurbishing
places. The machine manufacturer quoted us over $18,000 to replace it.
Todd Zuercher
P. Graham Dunn Inc.<http://www.pgrahamdunn.com/index.php>
630 Henry Street
Dalton, Ohio 44618
Phone: (330)828-2105ext. 2031
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Normally a ballscrew is not "springy or spongy" anyplace. Usually the
balls wear more than the screw or nut. Reballing a nut is not hard or
expensive.
Does this have an external ball track?
Is the backlash more in one place than another?
Ed.
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