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.
Doug, I'd look at the thrust bearings, and check to see that the graduated dial had space between it and the housing.
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.....
Brinneling?
Perhaps the ballnut isn't exactly lined up with the end bearings. You get a ballscrew trying to work on two different axes at the same time, and it sometimes finds a way to let you know things are off. Is there a movable bearing holder/pillow block of some sort on either end? If so, see what happens when you unbolt it. If the screw pushes the bearing block to the side or anywhere else, things aren't lined up properly. What does the block do if you turn the screw while it's loose? Another thing that just went through my mind would be to find a way to check pitch diameter at various angles of rotation. Things might not be as concentric as people assume. Happy hunting.
Later,
Charlie
Thanks to all the helpful hints.
And thanks for all the fish!
Pete
And the answer is ... 42
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