Shaft Trouble?

[Dan Graves]

I have a grinder that I built. Have had 5 great years on it. Now my belt shifts a 1/16 or 1/8 every revolution. Could this be the shaft and if it is, is there a way to check it. The pillow blocks are in good shape, any hints on what to check and how?

[mike koller]

I have some belts that run that way on their own. So... try a few other belts, check the idler (if you have one) and all other wheels for any crud build up that may be throwing things out of balance.

[Rob Frink]

Dan,

I would say that it is from the belts. I've seen it over and over. Some belts run better than others.....even the same type from the same box. I think it depends on humidity changes and if the belt was left on the machine over the weekend.


Here is the quick check to determine belt or machine. Carefully watch to see if the belt moves the same amount at the same spot on the the belt.....say 1/8" every time the belt goes around once....you can even mark that spot on the belt. Since most of the other wheels on the grinder turn 6-15X more revs than the belt...you should expect the belt to jump 1/8" several times for one rev of the belt if you have problems with a wheel or bent shaft.


If this explaination wasn't clear...please let me know and I'll keep working on it.

I'd say with 99% certainty...it's the belts.

Please let me know,

Sincerely,
Rob



edit: grammer/spelling

[Dan Graves]

Thanks guys. Will check tommorow as I have a bad cold. Got me laid up. Will let you know.

[tmickley]

It's curious, but I've had belts that wobbled on a big wheel, work fine on a small wheel and vice versa. When I get worried about it, I switch to a different brand or a known good belt and it goes away every time.

[allan lanigan]

I,ve just had the same problem with trisac belts,was drivin me crazy, what Rob says is true, he has described it well, I also thought i had machine problems.




















r

[Geno]

Turn the belt over and see if it tracks the other direction.
If so, it is a bad belt.

[StevePryor]

I had this problem a little while back and it was the belts. Five out of the twenty belts I had hanging by the grinder would wobble.

[Dan Graves]

Yes it is better on some belts than others, but still a problem. A friend of mine said it might be the drive rubber belt. He said that they can retain thier shape when left overnight, turn grinder on and wobble until heated up. Has any one experienced this, and what type of drive belts do you use?

[allan lanigan]

Your drive belts should not cause your sanding belt to wander unless it is setting up vibrations or you have a bad bearing, I use automotive type belts they seem to be higher quality than the industial ones , Most of the industrial belts i have used seemed to have a buldge in them which would set up vibrations..