Grinding Belt Wobble... Need Help Please

T

TheCivilman

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Oct 1, 2007
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I have a home made 'KMG' type grinder. I work at a welding shop/machine shop and all of my parts were made there. The only thing I was not able to do was balance parts. (shafts, contact wheel etc.) Everything is square and true. My problem is a tracking issue. The belt tracks str8, or a least stays on track when set but it continually moves back and forth about 20 thou. with a 'wobble' type issue happening. It acts like the belt splice is out of alignment but I believe this not to be the case. (I have checked with several different types and makes of belts.) I have also tried different contact wheels and a slack belt attachment with the same results. :grumpy:
My idler wheel and contact wheel is bang on, checked with a dial indicator, and there is only a few thou difference in the drive wheel/pulley. The idler and contact wheels are square faced and the drive wheel has a slight crown for belt aligning. The drive wheel is secured to the shaft with two set screws in a keyway.
Does anybody out there have suggestions to get rid of the 'wobble'? I am going to try a square faced drive wheel with slight flanges on the outside to stop the belt from tracking off but I am not convinced this will work. Any suggestions would be very welcomed. Thanks guys. Kevin :cool:
 
I'd say .020" wobble is small. I have had some, especially the fine grit belts that were all over the place.

My theory is no splice is perfect, just my 2 cents worth.

I have two home built grinders, one uglie, one better fashioned like one of Wayne Goddards in his book, it is a really slow speed for final shapening and sharpening.
 
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onley .020" thats small potatos. mine when i first built was wobbleing more then that. with a new fresh 60 grit belt i would say .060-.125" of wobble. but now every thing has smoothed out very nice. when the belt gets broke in then it will track better. but right out of the gate with a fresh belt and your getting .020 thats nice. is your tracking wheel crownd at all. if its not it should be, try putting a few wraps of electrial tape around the center and see how that works. I would bet thats your problem.
 
I have the drive pulley flat and the idler with a crown. Wrap thre center of the contact wheel with say 5 turns of 1" masking tape. For sure not duct tape. and give that a try. Also make sure your idler isnt a bit loose and can moe side ways . But hey .020 isn't much . Frank
 
If the belt goes from the drive wheel ...to the idler wheel....to the contact wheel, and the idler and contact are flat, the belt will wobble a bit. Dome the idler and the problem will be less. Some belt wobble is normal . 0.020 isn't a lot, so I would not let it worry you, but I would still dome the idler.
Stacy
 
TheCivilman said:
I have a home made 'KMG' type grinder. The belt tracks str8, or a least stays on track when set but it continually moves back and forth about 20 thou. with a 'wobble' type issue happening.
Click to expand...

I had a wobble issue with my home made KMG style grinder. Once I dommed the idler the wobble was reduced quite a bit. Testing with tape on the center of the idler as others have suggested above should make a difference.

Eric
 
One cause of belt wobble can certainly be the belts. Belts that have been around for a long time, especially in humid environments, are subject to be out of shape, causing them to wobble. Lately I've noticed that some Norton belts have arrived not cut straight. I had to send an entire order of Blaze belts back not long ago because every one of them had a "bulge" on one edge, like the cutter they used to produce the belts was really dull.

I've discovered that many times, if a person experiences belt wobble, they immediately think something is wrong with their grinder.....more often than not the grinder is fine, and the belts are to blame.
 
My clone had some wobble with some belts, almost none with others.
Increasing the belt tension fixed the wobble in several cases
 
Wayne Goddard showed his solution for wobble. He bolted a piece of hardened steel next to the belt so that it contacted the belt.
I don't think that much of a wobble is a problem. I use a file if I need it that close.
Just what I do,
Lynn
 
Wobble comes from the belts, good ones don't wobble so your machine is not likely to be the problem. About the only thing that helps is to tighten the tension, or if the belts are really bad return them to the supplier.
 
Thank you for the great responses and input...

Many different thigs to try.

My original set up had a crown on the idler & drive pulley and in an effort to reduce some of the wobble I installed the square faced idler wheel while keeping the crowned drive wheel. It seemed to help some. I have also played around with the tape idea trying different widths and numbers of wraps etc. on both the idler and drive wheel separately as well as both at the same time. Wobble still there though. I will try some different ideas put to me here and report back. (I guess that 0.020" is not much but when viewing different videos of fellas grinding, the belts seem dead str8.)

...Question: Should the contact wheel not be square faced or 'flat'? I always thought so but maybe it is not a concern.

Again Thx for all the input. This forum is great!:thumbup:
 
I believe everything here has been answered. I thought I probs with my Bader, but the belt was a bit loose. Crown on idler ,flat drive. I tape my idler, though just to save the crown. Finally .020 is fine by me. Good luck
 
it is definatly the belts...i bought some 3m trizact belts that did the same thing...then i tried a 3m cubitron belt and no more wobble
 
That would not indicate a bad belt. A trizac belt has a soft, flexible backing. A cubitron belt has very stiff, hard back. The hard back belts won't wobble any at all. Apples and oranges.
Stacy
 
Nevermind; I missed something in your initial post.

One thing we did in days of poorer belts was to set them up tight as heck and let them run 10-15 minutes to stretch them to the machine a bit.
Don't leave a belt on the machine tight when not in use, BTW. They stretch over the crowns.

KMG has an intentionally rough surface on the crowned idlers and drives, in case that may help.....
 
The only time I have ever had a problem is when I put a fresh belt on, then grind grind grind, then turn the grinder off and leave the belt on the machine without it running for a few minutes. I go to turn it back and and VOILA a wobbly belt.
 
I agree with those lining up to shift the blame to belts...

As I became better at grinding and able to purchase better quality belts...I saw huge leaps in the quality of my grinds.

Also as I refined my process I weeded out the oddities..and also a lot of the "trouble spots".

Listen to Ed Caffrey....he's good people.

Shane
 
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