I have an R1202 ballscrew mounted in a double row angular contact bearing (3205A2R), held by locknuts, the ballscrew has been machined to a tight slide fit and the runout on the ballscrew is +/-2um, the bearing is held in a housing which holds it tight, there's no play whatsoever. Yesterday I bolted the housing + bearing + ballscrew to a mount plate and here's what I got:



Any ideas why it wobbles / wiggles so much? the funny thing is that I had it mounted to a ballnut with some load on it and it rotates without any issues within the ballnut. Could it be that minimal load is needed for the bearing to work correctly?

Regards,
dsc.