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Talk about shaft and housing fits and roundness

When ball bearings have been processed with CSL, the CSL fills the entire space between the inner and outer race for the width of the bearing. It will mold around the cage and form to the geometry of that space. Since the graphite is a non-flexible solid, its roundness is determined by the roundness of the bearing (occasionally a bearing may be somewhat out of round and processing with CSL is not possible). Spin a processed bearing on your finger and you will see that it spins very free. Of course, there is still a very, very small gap between the CSL and the races allowing the balls, and not the CSL, to bear the load.

If the bearing processed with CSL is forced onto the shaft or into the housing that gap could be closed and cause drag in the bearing. This drag will produce heat in the bearing causing the metal to swell and tighten up even more. It is easy see how this situation can quickly snowball into bearing failure. The same bad results will occur if the shaft or housing is out of round, even if proper fits are followed. The reason is an out of round shaft or housing will cause the bearing to take the out of round shape (because bearing steel is flexible) and again the gap may be closed. So if the bearing spins poorly when installed, or if it gets noisy after installation, check for proper fit and roundness.
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