# BK12/FK15 Bearing Housings



## TomS (Sep 23, 2014)

I'm working on calculating ball screw lengths for my PM-932 conversion and have not been able to find a spec sheet on BK-12 and FK-15 bearing housings that clearly shows the length through the bearings and spacers.  The best I can determine is it is 30 mm for the BK-12 housing and 32 mm for the FK-15 housing.  Is this correct?


Do these housings come with bearings, seals and spacers?  The eBay ads and my web searching are not clear if these items are included.


Thanks in advance for your help.  I'm sure I'll have more questions as I move through my project.

Tom S


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## jbolt (Sep 23, 2014)

Tom, see attached.

Jay


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## TomS (Sep 24, 2014)

Hi Jay,

Thanks for the info.  These are similar to the drawings I have but I can't determine if the spacer and bearing stack-up is the same measurement listed as "L2+L3" for the BK12 and "E+T1" for the FK15.  How about the bearings, seals and spacers; are they included?

Thanks,

Tom S


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## jumps4 (Sep 24, 2014)

Tom

 I have purchased quite a few of these from china on eBay and everything was always included if it came with the ball screw.

 the housing, bearings, seals and spacers come assembled.

If you purchase the ball screw separate, you will also have to purchase the nut to fit the bearing end of the ball screw most of the time.

 The bearings I have purchased have always needed a modification to be able to adjust a preload. the problem is the inner and outer races of the bearings touch each other before the bearings are preloaded and a spacer is needed between the two outer races to keep the two inner races from touching each other when the preload nut is adjusted. also disassemble, clean and lube the bearings before use making sure the bearing are facing the correct direction. I have found them assembled from the factory wrong.
Steve


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## jbolt (Sep 24, 2014)

Attached shows standard shaft dimensions. 

As Jumps4 said, they come pre-assembled with bearings, spacers and seals. 

Jay


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## TomS (Sep 24, 2014)

Steve and Jay - thanks for the info and answering my questions.

Tom S


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