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pntrbl
04-20-2009, 12:48 AM
I have a wild ass bench grinder I use for hog work so I was real interested in the "Balance Your Wheel Once" article in the recent edition of HSM. While well and clearly written it still leaves a dope like me with some questions.

The author mentions pouring lead in the wheel centers, but I'm left wondering if this is just to correct the hole size, or is it an essential part of the operation? On my particular wheels the 5/8" holes seem to have a reasonable fit. Without clamping I can detect radial play but no up and down movement.

Obviously leaving the pouring of molten metal out bit makes it a lot easier but if it's essential for success ....

Whaddayu guys think?

On another note I believe I see an open unguarded wheel being used in Photo #9. I am guilty of the same myself, lol, but I could be persuaded to change my ways.

The only direct knowledge I have of an exploding wheel is from a friend of mine that unthinkingly ran it over 3450rpm. I forget the particular motor and pulley combo he used but I do know he went directly to the hospital with abdominal shrapnel over it. I've seen the scars ....

So how many of you guys run open wheels? Does anybody have any direct personal knowledge of accident/injury from the correct use of the same?

SP

J Tiers
04-20-2009, 01:30 AM
Not a direct answer.....

But the 'guards" I have seen on many grinders do not look as if they would either survive a wheel explosion, NOR contain the debris effectively.

Thin cast iron, 24 ga steel... friction retained flip-up plexi shield.......vs 8" wheel...... my sense of proportion tells me it ain't gonna stay in there.

Might as well run it open and stay off to the side... at least you will know it is not safe, no "false hope" that the shield will hold it and not become one with your body along with chunks of wheel.

Doc Nickel
04-20-2009, 02:04 AM
Two things:

One, never run a wheel without guards if you can possibly help it. I've never had a wheel explode, other than a chunk flying off a thin 3" cutoff wheel in an air grinder, but it's still possible, and even thin guards can at least slow down the shrapnel.

I have a monster 2HP Queen City pedestal grinder that takes 12"x2" wheels. The original guards have been shattered and rebuilt at least twice each- the end caps are entirely gone, replaced by shopmade covers formed from 1/4" steel plate. One motor endbell was cracked and rewelded.

I have no idea what caused the damage- the spindle/rotor still runs extremely smooth and true, but you bet your boots I'll be using it with the full guards- I'm actually thinking of building entirely new wheel guards, since most of what's there is brazed cast iron.

I doubt I'll be using the grinder anywhere near as hard as the previous owners- it came out of a prison shop- but a 12" wheel is going to have way more energy than a 6" wheel.

And two, I don't care what anyone says, the article about drilling a wheel and filling it with lead was stupid and irresponsible. If the wheel is that badly out of balance, replace it. Period, end of conversation.

If you buy good quality, name-brand wheels, you shouldn't have any problem. It's worth paying a little more for the good stuff.

Doc.

huntinguy
04-20-2009, 07:17 AM
I have heard of drilling and filling, known guys that have done it. However, that dates back to a time before rocks... ok, just after rocks were invented. Even at that, older wheels had density variations in them from manufacturing and you would have to periodically rebalance anyway.

Most quality modern wheels, for a bench grinder, will not need such work done. in fact I have never heard of balancing a wheel for a bench grinder.

Surface grinder, on the other hand, are a different story. I am sure a search of this site will bring more information than you care to read about.


I lean with Doc on this one.

ulav8r
04-20-2009, 10:41 PM
I don't believe there is a proper use of an unguarded wheel.

I had a 2"wheel on a handheld Milwaukee grinder explode. It cut a gouge in my glasses that was half the thickness of the lense. After that it hit my forehead. I was extremely lucky that the damage wasn't worse.

Carld
04-20-2009, 10:50 PM
pntrbl, I personally would not pour a lead center to bore out. I would ream or bore oversize and make a bushing to center the wheel.

Any guard at all would be better than none at all. even a sheet metal guard would slow the parts some. I have never had a wheel explode but I suspect the pieces would come out the open area of the guard anyway and do some damage.

JCHannum
04-20-2009, 11:02 PM
The article in this month's HSM details pouring lead as a means of reducing an oversize hole, not for balancing. It is a common method of accomplishing this, and has the advantage of retaining the balance when the wheel is removed and replaced. Bushings can slip and throw the wheel off when remounting. Some wheels are furnished with lead sleeves installed.

pntrbl
04-20-2009, 11:12 PM
Thanx for the collective wisdom and advice gentlemen. I have the original stamped steel guards which incidentally have a pair of threaded holes to mount a table. Fabricating a table is a good little project. :D

I have noticed upon closer examination that there's a bit of "egg" on this 8" wheel I'm using. With a dressing stick and a table to true it up from maybe I'll be able to get it to quit shaking the shop ....

Thanx again.

SP