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Tolerance for Wheel Bearing in Aluminum Hub?

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DaveBarbier

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#1
I've seen this question posted a lot in other machining forums but I'm still confused.

I'm machining a motorcycle hub spacer from aluminum to put in a wheel bearing. It needs to be press fit and I just want to know what the ID of the bore should be. Most answers I've seen are something like "check with the manufacturer of the bearing", so I'm on their website and think I found some info that will help but I don't really know what I'm looking at. I was hoping for a PDF saying something like "the bore ID for this bearing should be .0005" under size", or something like that.

It's a KML 60/22-2RD bearing which is 44mm OD and 22mm ID. Can someone help me out? Here are some links that may help.

http://www.kmlbearingusa.com/produc.../metric-single-row-deep-groove-ball-bearings/

http://kmlbearingusa.wpengine.com/wp-content/uploads/2016/02/P174-DG-Internal-Clearance.pdf

Thanks!
 

Chipper5783

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#2
Look up "Limits and Fits" in your Machinery's Handbook. Most bearing manufacturer's will provide a chart which documents the tolerances for "fits" of bearings on shafts and in bores. Google "Bearing Fits" and you will find many charts to reference. It is still up to you to determine what fit to choose.

For a one off home application, identifying the tolerance for the interference is less critical, because you will cut to the actual number

The simple approach is to allow 0.001" interference per inch of diameter - that will be a pretty solid press fit. Because it is an aluminum bore, you life is easy, you get it all set up at room temperature and heat the hub and the bearing will drop right in. So 44mm works out to 1.7322" so bore that hub to 1.7305".

Perhaps the biggest challenge will be accurately measuring that bore. I'd suggest practicing on a scrap first.

Let us know how you make out. Regards, David
 

Wreck™Wreck

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#3
1.732" +.000 -.001 will give you an excellent fit, I am not a hobbyist so I ignore the tenths in such work, the easy part will be measuring it and the hard part will be doing it.

It is a spacer, if you do the first one wrong do it again.
 

DaveBarbier

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#4
Thanks guys, I've done some more reading and re links I gave earlier weren't useful. Those were internal clearances of the bearings. Like the tolerance from the ball bearings to the outer and inner races which is known as C2, CN, C3 and so on.

I found another page on that site that just says use an interference fit so I'll use the .001" under size for my housing. I'll also read through my Machinery's Handbook.

As for measuring it properly, I was going to use a .0005" increment dial bore gauge.

Thanks!


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