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Truing grinder wheel

Posted by spambdamn_rich (My Page) on
Tue, Dec 13, 05 at 23:04

I've had this Harbor Frieght 8" bench grinder for a while, and just recently decided to repalce my trusty 6" Delta with it bolted to the workbench (the Delta just sat there free).

Well, the HF grinder shakes like a lawnmower. I found that by greatly tightening the mounting bolts (to the bench) I could reduce the shaking, but the real problem seems to be that the wheels are out of round (a commong HF grinder wheel problem, I understand). I tried dressing them with a star dresser, to no avail. Then I dismounted the wheels, found the heavy (long) spots, put those up high, pressed down a bit, and tightened up the wheels again. That helps a bit.

Then I took some 1/4" steel stock (Simpson Strong-tie flat washers for foundation work) and tried to use them to help wear down the high spots on the wheels. That may have helped a bit, but I think it might take quite a while to do that. Part of the difficulty is that the tool rests on the grinder are a bit too flimsy and springy to hold a trueing steel to them steadily enough to hit only the high spots.

So... my question is, is there a good in-shop/on-grinder method to true a pedestal grinder wheel?


Follow-Up Postings:

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RE: Truing grinder wheel

It's not easy but can be done.
When mounting the wheel, make sure the wheel you put on is as round as possible, you can dial in the wheel, but first, put a layer of tape over the outside, so the dial indicator stem doesn't get scratched up. If the wheel is still out, I usually dress with a Industrial diamond, mounted on a block of steel, the base holds a key, where it slides in a key-way on the tool rest of your grinder.
The diamond I have mounted in a screw [fine pitch] so you can turn and advance when dressing.

These Star type dresser as you mention, don't work very good, they have to be large and heavy, this makes them less vibrating and jumping when grinding high spots on wheel.
You can try this with yours, .. by holding with one hand a heavy piece of steel bar or plate on the end of handle while dressing, [do not push hard, otherwise you follow the uneven pattern of the wheel] to make it less bouncing back and force.
Good luck.
Konrad


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RE: Truing grinder wheel

Spam,

You need to get a dressing stick. It's just a super hard, abrasive material that will get that wheel back into shape and balance, quickly. I use mine all the time on my Dremel grinding tips. It's amazing how that tool will be growling, vibrating and struggling to turn with an out of balance tip, and just smooth out beautifully when it gets trued up.

GG

Here is a link that might be useful: Dressing stick


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RE: Truing grinder wheel

These dressing sticks do not work very well for heavy 8" Grindingwheels...it will only follow the extcentricity of the wheel.....not heavy enough.
They work OK for small and light wheels.

Konrad


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RE: Truing grinder wheel

Thanks, Konrad and GG.

Before I saw your replies tonight, I took another stab at quieting down the HF beast.

Basically, I adjusted each wheel so that it had the minimal amount of runout. There's enough play in the center holes to do this. Then I adjusted the orientation of one wheel to the other to minimize static turning (weight balance).

OK, I know that it would be best to have the wheels weight balanced and concentric, but... this works well enough for now. The grinder is much quieter at speed than before. It does go through a fair amount of shaking at half rpm's, more on spinning down (takes longer) than spinning up.

I am considering replacing one or both wheels with higher quality numbers. But for now, this works ok.

I did first try truing the wheel with a small diamond dresser I use for my tool grinder... but this didn't seem to work all that well.


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RE: Truing grinder wheel

I hadn't thought of sloppy fit on the arbor. Every wheel I've ever mounted on my grinder had no play. Large wheels will cause major problems with vibration if they are off center. Running a grinder with wheels that are out of balance, create vibration that will destroy the bearings if it is bad enough, as well as making the machine work harder just to spin the wheels. You'll really see how much it loads the machine when you turn it off. Out of balance wheels will cause the grinder to stop faster, while wheels with good balance will take much longer to slow to a stop. Compare that to what I said about my Dremel bits being out of round. And they are less than an inch in diameter.

I think you would do better to toss the wheels and get a good brand like 3M/Norton or similar.

GG


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