BK12 end float?

[irving2008]

Hmmm, the plot thickens. Made some shims for the outer races and still have end float. With the bearings on the ballscrew, not in the housing and the lock nut tightened fully, the outer races have around 0.3mm of play in them...so no matter how solidly fixed the inner and outer races are, the play is in the bearings themselves. Am I missing something here, or is it the "china" bearings that are crap?

Are you sure you have the bearings back-to-back? If not, you won't be able to preload them.