How do You Make a Belt Grinder Wheel?

[SteveHGraham]

I found a bearing at the local Grainger. They want almost ten bucks, which seems ridiculous. I can probably get it on Ebay with two-day shipping for less.

http://www.grainger.com/product/DAYTON- ... =P2IDP2PCP

Thanks for the help with the bore.

For future Googlers, I will add that a bearing with a half-inch bore will work with a half-inch bolt, even though the bolt will really be more like 0.440" in diameter. How do I know this? Because other people do it. The size is R8-2RS.

[SteveHGraham]

Now I have to deal with making the bearing seats (holes, whatever they're called) the right size for a good fit. Something I have never been good at.

Guess I'll have to put this aside after making the bore and cutting the pulley to length.

[warmstrong1955]

http://www.vxb.com/page/bearings/PROD/Kit7478

I've bought a lot of bearings from these guys over several years.

No complaints.

[SteveHGraham]

Thanks. I decided to do Ebay. Four bearings shipped for eleven bucks. Now I have to find some dimensions so I can bore the hole.

[SteveHGraham]

I can't find dimensions, so I guess I'll just subtract 1/4" from the OD of the bearing. So 0.875".

[redneckalbertan]

All it said was that a pulley 300mm across would have a crown 3mm high. So 3% of the width.

Is that a typo? 3mm in 300mm is 1%

[refinery mike]

you can get bearings reeeeel cheap on ebay. i would suggest 6201,6202, and 6203 bearings for most things with a radial load only. and then you can go into 7201 etc for radial and axial loads. (same physical size) Those seam to be the common bearings used. They are metric sizes but you can get them anywhere and about half the price of the same bearing in an english size. I think the metric people have standardized bearings where we are still all over the place with sizes so they can be made cheaper. If you open up most bench grinders, small drill presses, belt sanders these are the bearings in almost all of them. you can get them in about every type and grade. I would suggest sealed bearings rather than shielded bearings for a sander.

[SteveHGraham]

Sorry; I went to school in Canada.

Actually, it is a typo.

[SteveHGraham]

If you open up most bench grinders, small drill presses, belt sanders these are the bearings in almost all of them. you can get them in about every type and grade. I would suggest sealed bearings rather than shielded bearings for a sander.

As luck would have it, I picked sealed.

[SteveHGraham]

Hmm. Looks like I got the tracking wheel confused with the idlers. Most grinders I can Google up have tracking wheels at least 3" in diameter, and I am looking at 2.25". Wonder if it will matter.

I don't care. I'll go ahead and make it, and if it sucks, I'll turn it straight and use it for an idler.

[BadDog]

As said, your ID through bore of the idler should be only slightly smaller than the OD race dimension. Just enough to locate the bearing positively, but still allow the outer race to be used for bearing removal if needed. And that ensures that cages/seals/shields are not interfered with by the ID of the roller. Likewise you want the step on the shaft (bolt or otherwise) to bear only on the inner race, but normally that's not a problem since it is usually proud of the bearing surface anyway.

Ignoring platen and inside attachments, there are 3 wheels on most of this style belt grinder.

The contact wheel is usually 6" to 8" or bigger (up to about 12"), with a rubber tire, often with slotted surface.. Some use casters. Or buy a "real one", often from Grizzly, or other sources like ebay. A few people make their own. This is free running mounted on bearings, and given the loads it may experience, you might wish to put larger bearings here (if making your own).

The idler is generally on the top ahead of the contact wheel (from belt travel perspective). It is mounted on a rocker to aid in proper tracking, and has a low crown. I've seen these in the 2-3" range, so yours should be fine. Most designs also use this wheel for belt tension, usually with a spring and lever arrangement.

The drive wheel is the only one not mounted on bearings, and is either keyed to the drive shaft. This may be an intermediate driven shaft, or the actual motor shaft. It's size is governed by having sufficient surface to grip and drive the belt as well as being the final arbiter setting the sfpm of the belt. If you have a fixed speed motor and direct drive, then the diameter will be directly determined by desired SFPM, and so on. These may be in the 3 to 5" range, and have no crown for full contact for driving the belt.

Variations include 2 wheel systems where the idler is eliminated and it's functions divided between contact and drive. Or platens with idlers top and bottom, often of different diameters and with rubber tires to function as small radius contact wheels, or even as large(er) gap inside grinding attachments. Inside grinding attachments may have wheels as small as 1", but smaller diameter can have a direct trade off with belt life. And the list goes on...

[duckman903]

I'm going to jump in now, you need a spacer in between the bearings so when you crank the mounting bolt you don't pinch the inner races together which will cause them to fail very fast. Your spacer should be the same length as the shoulder measures.