Proper ball bearings for rollers on homemade belt grinders

B

blackboogers

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Jan 16, 2002
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For those who know, what style and width ball bearings do you use (roller.ball,etc). Does the bearing need to cover the width of the roller (2" wide roller/1.875 wide bearing) I'm making a 2x72 belt grinder. Any info is greatly appreciated.
 
rob frink is a great guy to work with and i can't see a reason way he would not share his knowlegde about the proper bearings for your needs.
 
Hurl,

Here is how I make my rollers and contact wheels:

I use two bearings with a spacer in between. The spacer fits against the inner races and allows you to mount the roller with a standard 1/2" bolt. It is as easy as bolting the roller to your machine frame. You can see the cutaway roller for details. I use this method for almost all of my wheels ...from 1.5" up to 10" diameters. The bearings have a slight press fit approx .0002"-.0005". I use deep groove radial ball bearings with rubber seals. They carry an ABEC1 rating which is a general purpose Motor grade bearing. I use the english size "R8" which has a 1/2" ID and a 1.125" OD and .312" width. The industry standard part number is R82RS which designates and R8 bearing with 2 rubber seals. They are available at any bearing supplier/power transmission dealer. As an alterantive you can use the ISO series such as the 6000 series which have metric dimensions instead of English dimensions. Grab a catalogue for the sizes...there are many!

If you need any more info, let me know...I'd be glad to help if I can.


Good luck with your project and have fun with it.

Sincerely,
Rob
 

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Thank you very much for the graphic illustration. I was wondering how you keep the axial end play down. Just one queston though, on your press fit do you mean 2 to 5 tenths of a thousandth or .002 to .005 press fit? I'm sure its the latter but I want to be sure. I can get ground shoulder bolts thru Mc Master-carr, is that necessary or over kill? I think its great that you will show how you make a product that you sell. It shows that you stand behind your product and the quality therein. I have a dynamic balancer at the shop I work at (we go to G2.5 which is good to 3600 rpm or however a tol. you want)if you have something you want bal. let me know. I'm in the Cincinnati area. Thanks again.
 
yep, the axial play issue is the primary reason for this design. I've used several methods including retaining rings and belleville springs for axial preload. Also, this method simplifies mounting. When you tighten the bolt, you clamp the inner races and spacer together against your machine frame.....very rigid and smooth running. Hence no need for stripper bolts or anything fancy (expensive$). The basic KISS principle in action.

The press is 2-5 tenths! not thous.....001" interference will cause this size bearing to run rough because the inner clearances get squeezed together too much. It is a standard spec that the bearings are design for.....The interference changes with the bearing size....bigger bearings have a wider tolerance for fitting.

Don't let the fit scare you...it doesn't have to be that technical. Just bore it close and tweek it with a polishing flap on a die grinder. Red locktite will fix some slop if you over-bore it.

Take care,
Rob
 
SKF 6000 Series either doublr sealed or single sealed with the seals facing out. Press on the roller and slip fit on the shaft with either snap ring grooves or shaft collars on the shaft. Deep groove ball style is the best in this application - good radial clearance, misalignment allowance and load capacity. MSC Supply or McMaster Carr.
Ed
 
Here is a bit of a backwoods type idea that worked for me on my homedone 2x27: use timing belt bearings out of Volvo cars from the scrap yard. They are about 1" wide, 2" diameter and you can put two of them on a long bolt and mount were needed (the bolt size that fits best is 20mm metric). They are easy to remove from the cars just under the timing belt cover. They are what was used for roller bearings on my flat platten, and have stood up great. (My dad is a bit of a tinkerer, and also drives old Volvo's.)
 
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