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Question on Bearing cup pocket size?

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Mike8623

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#1
OK guys I've got a project where I have to mill a hole for a race (bearing cup) and insert a bearing. My question is how much undersize should you mill the pocket to press in the race (cup)
 

Ray C

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#2
Without knowing exactly what bearing you have it's hard to give an exact answer. Generally speaking, you do not want a very tight fit at all. I'm assuming a taper bearing of around 1-2 inches or so. Maybe 0.0002 to 0.0004". Anything tighter than that and you risk damaging it or warping it out of shape.

Ray
 

mikey

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#5
Whenever I need to bore a hole to fit a bearing I contact the bearing manufacturer by email and ask them for clearances. There are so many different bearings and the fit has a direct impact on internal bearing clearances. The maker will know what you need. Being able to bore to that dimension, which will usually be in the micron range ... is another thing.
 

Mike8623

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#8
I'll be placing the bearings (2) in aluminum. I'm actually making a rifling machine for my lathe and am using two wheel bearing for a shaft on which a pinion gear lives and interacts with a gear rack.
 

BtoVin83

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#9
If using tapered roller bearings you can utilize a fair amount of press fit as the bearing clearance is made up between the bearings, ball bearings the clearances are built in and cannot stand much press. Tapered rollers don't like out of round.
 

Mike8623

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#10
I want to thank all that replied. I got just the type of answers I was looking for from the forum, thanks again.

I was born and raised in Bakersfield, but moved to Montana a long time ago.
 

BtoVin83

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#12
One more thing, with aluminum housings we put a tad more press on the bearings compared to steel as the aluminum can heat faster and expand faster and sometimes the brg can start spinning. Nice thing about tapered brgs they can stand the press and not self destruct.
 

cg285

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#13
i always understood it was the grade of tapered bearing that allowed more or less press fit. c3 comes to mind as one with looser tolerances that has a greater press acceptance
 
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