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Needle Bearing Fit Question

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ddickey

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#1
How are needle bearings supposed to fit?
I need to replace two. Low load and speed. It's for a table on a small surface grinder. They fit tight in the housing but the shaft is a loose fit,
 

Desolus

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#2
There's quite alot of needle bearings out there, you will need to give some more information. I've seen bearings held in a housing by everything from glue to a, well come to think of I don't know what it's called... like a reverse e-clip...

Pictures if possible.
 

ddickey

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#3
They're open cup full complement I think they're called. I've installed them. Made a new shaft as the old one was worn .003" from the OD. I did some searching and thought I read for my size 1/2" x 11/16" x 1/2" shaft diameter could be .001" larger so .501" in my case.
 

benmychree

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#4
The shaft should fit with very little clearance; soft shaft and needle bearings is a very poor thing to do; ideally the shaft should have a hard race on it or the shaft should be hardened.
 

Asm109

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#5
If you are talking about drawn cup needle bearings where the outer race is a thin sheet metal shell, then....
They must be press fit into the housing because the roundness of the housing is what makes the bearing accurate.
Also the shaft needs to be hardened into the Rc 55+ range. I am going from memory but a cold rolled shaft won't last long.
 

ddickey

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#6
Yes. That's what I've been reading.
Thanks guys.
 
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