Bench Grinding Wheels

In all my career in the many shops I worked in I'd never experienced the cluster I went through when I had to replace my old HF 8" bench grinder I got for Christmas in the 80's. Even it didn't shake like the 8" Ryobi. The replacement Norton wheels were no better and even after making new hubs I could get the wobble out, but not make them concentric. Seems as though they don't care about that anymore. And even if they are concentric they are not balanced. The tool rests on most grinders are junk so it makes it impossible to use a dresser to true the wheel when out of round and balance in my experience.

After watching a YouTube on balancing the wheel on a Tormac SG and how they have a hub that uses bolts as balancing weights I though why doesn't somebody make that for bench grinders? Did a search and they do, it's called the Oneway. It's $80 and it's nicely made and I was able balance both wheels, then dress them true and tweek the balance again and the grinder runs smooth.
 
benmychree said:
Is the grinder in balance itself? I was given a HF grinder, a real POS; everything wiggled and wobbled, I made new inside and outside washers, changed to USA wheels, dressed the wheels true, and it still vibrates partially due to the motor being out of balance; that combined with work rests and the wheel guards that are made out of material not much stronger than a tin can, have me nearly ready to junk the damned thing.
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I also have a Harbor Freight 8 inch grinder. Did all the same things you did with all the same results. Unfortunately, I paid for mine. It doesn't seem to have a start winding so it takes forever to spool up and it vibrates so much the light has a very short life. I have my green wheel and wire brush on it. I only use that machine to sharpen my tungstens and the few brazed carbide tools that I have . I use insert carbide mostly. The wire wheel doesn't care about vibration. I get annoyed every time I use it but it works so I haven't tossed it. (yet)
 
jschmidling said:
What am I missing?
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The hole in the middle of a grind wheel is meant to pass the shaft easily. It obviously has to be located in or near the center of the wheel but there is no need for the level of concentricity required for something like the bore of a gear or V-belt pulley. Please note that I am only referring to general purpose wheels for bench grinders. Any bushing required is to keep the wheel located in the ballpark and allow you to respect proper mounting procedure.

When mounting a wheel, the clearance around the shaft allows me to dial in the grinding surface for a minimum of run out. This should provide the best balance prior to dressing as well as the least amount of dressing.

I understand if you want a way to swap out wheels regularly with a minimum of fuss. However, my approach is to have more than one grinder so that the wheel I need to use is only a flick of a switch away.
 
Tozguy said:
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When mounting a wheel, the clearance around the shaft allows me to dial in the grinding surface for a minimum of run out. This should provide the best balance prior to dressing as well as the least amount of dressing.
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I don't understand how or why you would balance a wheel that is not round or concentric. When you correct the eccentricity, you also change the balance. The slop in the shaft is a bit of fudge waiting to get you.

>"I understand if you want a way to swap out wheels regularly with a minimum of fuss. However, my approach is to have more than one grinder so that the wheel I need to use is only a flick of a switch away.

I have 3 grinders with capacity of 5 wheels. At the moment only one wheel works on one grinder. I made the big mistake of trying to improve one that was working.

js
 
Some of the whole process is counter intuitive. As I found out after run after run at my cluster. I checked the motor for balance, runout on the shafts and eliminated those. I didn't have play in the shaft fit with the plastic bushings I got with the Nortons. I made an arbor to mount the wheel in the mill and used a diamond nib to true the wheels. But they were still out of balance. So even with hubs I made they ran true but we're out of balance.

The Oneway setup fixed that with a little bit of mod like soaking the bearings for the balancing jig so they had less friction from the grease. The balancing jig also came in handy when I got a Baldor tool grinder clone off CL. One side of that grinder even though the shaft showed no runout the wheel wobbled. Thanks to Janderso who posted a YouTube about a real Baldor that had that prob and the guy made a tool to true the hub on the machine, I was able to fix the wobble and use the Oneway balance jig to get the green wheel and diamond wheels both balanced and trued.
 
It seems like what ever they use to mix the mud in is a serious expense item so they spend as little time mixing as possible. The obvious explanation for imbalance of a concentric wheel is that the mud in the wheel is not homogenized. Meaning that the mass varies in different sectors of the wheel and nothing will prevent vibration until this is balanced out with outboard weights as in balancing car tires/wheels.

As mentioned before, using a press fit bushing and a press fit 1/2" axle, rolling over a track, any pendulum tendency should be caused by eccentricity if the material of the wheel is homogeneous.

It's sad to say that this conversation would never have taken place 40 years ago. One bought a grinder, wheels and spent 5 minutes dressing if necessary and used it. When the wheel got too small 10 years later, you bought a new wheel dressed it and went on doing useful stuff.

Thanks China.... Go Trump!

js
 
jschmidling said:
It seems like what ever they use to mix the mud in is a serious expense item so they spend as little time mixing as possible. The obvious explanation for imbalance of a concentric wheel is that the mud in the wheel is not homogenized. Meaning that the mass varies in different sectors of the wheel and nothing will prevent vibration until this is balanced out with outboard weights as in balancing car tires/wheels.

As mentioned before, using a press fit bushing and a press fit 1/2" axle, rolling over a track, any pendulum tendency should be caused by eccentricity if the material of the wheel is homogeneous.

It's sad to say that this conversation would never have taken place 40 years ago. One bought a grinder, wheels and spent 5 minutes dressing if necessary and used it. When the wheel got too small 10 years later, you bought a new wheel dressed it and went on doing useful stuff.

Thanks China.... Go Trump!

js
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Agree with what you said. The wheels I use are Camel Brand, made in Israel. They have been great so far. Truing with the diamond has them spinning without vibration along with making flanges and bushings and adjusting for minimal wobble. I gave up trying to get Chinese grinding wheels to run true without excessive vibration.

Roy
 
royesses said:
Agree with what you said. The wheels I use are Camel Brand, made in Israel.
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Always interested in what works for others but they do not seem to offer a 6" bench grinder wheel.

On another tack, I had an interesting experience with one of the wheels that came with the WEN grinder.

I made a center punch out of an old 3/8" drill bit and the wheel rapidly took the shape of punch. By the time I finished, it had about a 30 deg list on the face and there was an impressive pile of gray dust on the floor.

I have an old brass hammer that I wanted to reshape the head a bit and by the time I finished that, the wheel was "dressed" back to flat and square.

Can you imagine what kind of junk that wheel was made from if it could be dressed with a piece of brass?

I remember when the Japanese taught us about QC and now we have the Chinese teaching us how to get away with selling trash and keep important customers happy with a very high level of quality.

js
 
jschmidling said:
I have an old brass hammer that I wanted to reshape the head a bit and by the time I finished that, the wheel was "dressed" back to flat and square.
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My 6" harbor freight grinder was noisy and jumpy. I just didn't do anything to it, just because it's a cheapo. Then one day, it starts to take for ever to slowdown when shut off. It is quieter and no walkie, jumpy.
I then learned that this thing work well if I treated it well. I should have dress it and try to true it up.

The funny thing is I have other grinders, one good name, one decent name, one 3 phase. But I don't use any of them. One needs new bearings or rebuilt. One is just heavy and the shafts was bent by previous owner (I didn't know much when bought that, thinking of decent brand). The other is 3 phase and very heavy. The harbor freight is light. I grab it outside, point a fan on me and off I go.
 
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