"Douglas Adams" wrote in message
...
We just had new ballscrews installed on our knee mill and are finding a
slight "vibration" or chatter while manually indexing the screw on the
x-axis. You can feel it occurring around the same position i.e. between 0
and 90 degrees rotation of the screw.

Their doesn't appear to be any interference issues between the screw and
the
frame.

Any suggestions on trouble shooting this one?

The installer is being dodgy on addressing this issue.



Could be alignment, loosen the support bracket on one end and drive the nut
to that end, then retighten....do this on the other end...repeat the process
a couple times.

Also, as Steve has alluded....the thrust bearings 'should' have been
replaced....could be old bearings, crud, or excessive preload in it /
them.....

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SVL