Vibrating Bench Grinder

[Todd Burch]

Several years ago (circa '89) I picked up what I thought was a nice, heavy duty 8" bench grinder from Sears. I've used it on and off over the years, but my smaller 6" grinder was always easier to drag out and use.

The 8" grinder came with a heavy cast iron pedestal and an overarm light with a 40 watt elongated bulb. The bulb was the first to go, and I never could find another "rough duty" replacement. It seem the vibrating of the grinder would cause it to burn out quickly. I eventually just removed the whole arm assembly.

It came with coarse and medium grey wheels. I replaced the medium with a fine brown wheel. I don't remember if replacing the wheel caused it to not vibrate as much. I guess the net result was no noticeable improvement.

I decided to quit moving it from under my feet a couple weeks ago and mount in onto a bowling-alley-top workbench. There are rubber pads on the feet, but nothing significant. I did tighten it down pretty good. I turned it on, and it came up to speed alright, but then it started shaking the whole bench. Pretty rough. I turned it off, and then the shaking got worse. Everything else on the workbench started walking around, all in unison, just like those green metal football games we had as kids. I had to grab stuff to keep it from falling off the table - it was bad.

I spun the wheels around manually, and they are obviously not turning on a flat plane. As you spin it, at the point closest to you, the wheels get closer, and then further apart when spun 180 degrees. Chicken toed - pigeon toed, and on and on.

So, my questions are, if this is a bent shaft, it must have been that way from the factory (shame on me). Or, could the wheels themselves warp over time (20 years I guess it has been now on the grey wheel, and maybe 17 on the brown wheel).

Or, it is time to put it in my garage sale this coming weekend? (and some how manage to get by with the three other bench grinders I have that operate satisfactorily... :rolleyes: )

[Jerry Bruette]

Todd,

Did you use a wheel dresser to true up the wheels after they were installed? That could be your problem. You could remove both wheels and then run the grinder and check for vibration.

If there's no vibration with the wheels off get a dresser and dress the wheels after reinstalling them. There'll be alot of grinder dust flying around when you dress them so you may want to wear a dust mask.

Good luck
Jerry

[Todd Burch]

Can you dress a wheel in the sides? (And should you have to as a matter of normal wheel maintenance?)

[Paul Atkins]

Do you have a dial indicator? Take the wheels and the flanges off and check the shaft. Not under power of course. If it reads true, get some new flanges that fit the shaft and are true, then try the stones and dress them. Lousy flanges are a big factor - get some turned ones rather than the pressed steel ones. Makes it a new grinder. I had a stone that had some oil soaked in on one side - tossed it.

[Todd Burch]

I have a drawer of dial indicators. Duh me. Thanks Paul.

[Jerry Bruette]

Todd,

Maybe I misunderstood the problem with your grinder. No you shouldn't try to dress the sides of the wheels, in fact you should never grind anything on the sides of the wheels either unless they're specifically rated for it. They could shatter under power and you don't want to be around if that happens.

I'll agree with Paul it could be the flanges are no good or are ill fitting.

Jerry

[Dan Forman]

I have never found a replacement wheel, including spendy ones from Norton, that are anywhere near true. They all wobble side to side, and are uneven in circumference. It would be nice if someone t=could get it right, I'd certainly buy a few.

Dan

[Steve Southwood]

I have a Delta that viberates real bad. I had never used it until I mounted to a bench. I went out and bought some bolts that fit the holes snug, can't remember the size. Tightened it down real good and stuff started moving everywhere. For some reason, I loosened the bolts and the vibration quit. It doesn't hop or anything. Might want to give that a try. I changed out the nuts to nylock, so she can't come off the bench.

[Tom Esh]

Truing (though obviously necessary) won't help the balance except by pure luck and the problem with just bolting or clamping it down to something heavy is it does nothing to reduce the vibrational load on the bearings. I have a Delta 8" that would walk the whole bench across the shop until I got one of these kits http://www.oneway.ca/sharpening/index.htm . Awesome! Zero vibration now from 0 -3600 RPM even with two 8" x 1" wheels.

[David G Baker]

I use the nylon inside of steel lock nuts on my grinders and don't tighten the nuts real tight. I also use the rubber inserts that fit in the mounting slots to isolate the grinder from the hard surface of the grinder support and the bolts. I like my grinders to float on the rubber isolation pads.

[Todd Burch]

Thanks Tom. I went to the link and read the data, and even the review by the other Tom.

But I am still scratching my head. What causes the wheel to become balanced with this system? Or, would I just be counteracting the out of balance by the use of their flange? (sorta like wheel weights on a car?) So if I had 4 grinders, each with 2 wheels, I would need the balancing kit, and then 3 more sets of flanges?

Would I register the flange via pencil mark when transferring the wheel from the balancer back to the machine?

[David Hite]

The instructions for installing the balancing flanges are on their website here. http://www.oneway.ca/pdf/balance_kit.pdf

[Tom Esh]

Thanks Tom. I went to the link and read the data, and even the review by the other Tom.

But I am still scratching my head. What causes the wheel to become balanced with this system? Or, would I just be counteracting the out of balance by the use of their flange? (sorta like wheel weights on a car?) So if I had 4 grinders, each with 2 wheels, I would need the balancing kit, and then 3 more sets of flanges?

Would I register the flange via pencil mark when transferring the wheel from the balancer back to the machine?

It does work much like automotive wheel weights. The balancing flanges have a machined groove or t-slot all the way around and the weights (capscrews, nuts, washers) are positionable along the slot. Instead of mounting the wheel directly to the grinder, you mount it to one of the flanges, balance it in the jig, then mount the balanced flange/wheel assembly to the grinder. You can move the flanges among different wheels but of course that requires re-balancing each time. If you swap wheels often, one flange per wheel would be ideal. With 8 wheels it's probably worth call to the mfr to see if you could get extra flanges at a reasonable price.

[Paul Atkins]

I still wonder where you guys are getting all these out of balance stones. I don't think I would trust a stone that was manufactured so poorly that it wouldn't be balanced with simple truing. When I worked at a nut company (I can hear you now) we had a butter machine that had a 30 hp motor that turned 5000 rpm with a 12" stone and was 'smooth as butter'. I'd bet that there was no room for a poor stone there.

[Tom Esh]

I still wonder where you guys are getting all these out of balance stones. I don't think I would trust a stone that was manufactured so poorly that it wouldn't be balanced with simple truing. When I worked at a nut company (I can hear you now) we had a butter machine that had a 30 hp motor that turned 5000 rpm with a 12" stone and was 'smooth as butter'. I'd bet that there was no room for a poor stone there.

The most un-balanced wheel I have is a premium Norton 3x. Had to fabricate a couple extra weights for it. Honestly I'm not sure anyone makes an effort to manufacture a truly balanced wheel. Either that or maybe they figure nobody spins a 8x1 wheel faster than 1700 rpm.