How to bore out the hole in a grinding wheel to enlarge it.

[george wilson]

If you have a wheel with a hole smaller than your arbor,you can just drill it out.

Stuff paper into the hole in your chuck so wheel grit cannot get into the scroll of the chuck. Best to take the chuck apart afterwards and carefully clean it if you value the longevity of the chuck's accurate life.

Select a HSS drill the size you want the hole to be. Try to pick out a drill that is not your most perfect one. The drilling may wear the sides of the drill a bit,making it slightly tapered.

Cover the lathe's ways with paper or plastic,NOT cloth. Cloth will let fine grinding dust through it because it is woven,and does have tint openings where the threads cross,BELIEVE ME on this-personal experience.

Run your lathe at the SLOWEST back geared speed you can get. The drill will drill right through the grinding wheel. Mount it in the tailstock,of course.

Clean your lathe carefully and oil it. I probably would have the nozzle of my shop vac close to the drilling action. I HATE loose abrasive dust floating around.

 

[Tony Wells]

Along the same lines, a profile on a grinding wheel can be achieved by roughing it out at speed with a diamond point or appropriate means, then turn off the power, and with a piece of flat stock with the desired shape held firmly, and rubbing against the wheel, turn the wheel by hand. It will cut the wheel with very little abrasion of the "template". Done many radii this way.

 

[randyjaco]

I think I'd rather spend the extra couple of bucks and buy a new wheel. Having had a wheel blow up on me, I don't want to to do anything that might disturb the integrity of that wheel. A spinning grinding wheel is a potential hand grenade. It has the potential to kill or maim anyone in the vicinity.

Be Careful out there!

Randy

 

[Tony Wells]

One of the better tool grinder guys I know, retired now, lost his right eye due to a white wheel blowing up. A chunk hit him square on his glasses and sent shards into the globe, along with fragments of the wheel. Pretty disturbing sight. Never underestimate the danger of any grinder. Use the guards, use your PPE, and use your head.

 

[george wilson]

Wheels can blow up,but if they still ring after boring them out,they are still uncracked and are o.k. to use. Your friend's white wheel had something wrong with it. Did he have a guard on the wheel?

The guy who taught me that trick was an old,vastly experienced machinist. He was retired,but machine shops in the Norfolk.Va. area still came to him with problems they didn't know how to solve. He solved them.

 

[Tony Wells]

This guy was an old timer, and I suspected at the time that he thought the wheel was safe, because I knew he was pretty careful, and did ring out his wheels. The problem was, in my opinion, we had a second shift that had access to the toolroom, so who knows what took place. He should have known to ring it based on that, and maybe he did, but I've never seen a wheel blow up that sounded good. There were factory guards on the T&C grinder, but a chunck about the size of a quarter evidently bounced in such a way as to hit him kind of from below, the best we could determine.

 

[george wilson]

Disagreeing is o.k.,and I appreciate your regard for me. The process has worked fine for me,and fact is,us old timers had to make do with what we had back when we were poorer. The old guy who taught me that trick was a lot older at the time,and I know from his bag of tricks,he had to make do way back.

I cannot see why a bored out wheel is risky as long as it rings. It is either broken,or it isn't. I've worked with machinery since 1959,and I never had a wheel I put on blow up.

What Mr. Wells said is true: When dealing with machines used by others,there is a LOT more risk than with your own machine.Someone could have given that wheel a whack with a wrench or something,and did not bother to inspect it,causing another person to lose an eye. There are a LOT of careless people working in factories and shops. Careless supervisors,too.

I was in a furniture factory in North Carolina once,a friend of the president, A supervisor was with me. This was in the 60's. A nearby workman was using a nail gun,and sort of tossed it on his bench. BLAM!!! That sucker went off,and sent a 2" nail bouncing off everything. That early gun must have had a delicate trigger!! The supervisor looked at him,but said nothing. Lucky one of us was not shot.

 

[george wilson]

Obviously we don't want to run a wheel with a chunk out of it,and you could tell that in the dark. The structure of wheels is not such that it invites some kind of internal structural damage by boring out the hole. It doesn't suffer internal structure damage from having its surface shape changed,does it ? A wheel is not like a piece of natural stone which has layers of strata or "grain" in it. It is made up of small crystalline structures that are friable,and designed to break off independently,exposing new,sharp crystals as it is used.

All I can say is that it has worked for me. Certainly a wheel with chunks out of it will ring,because it isn't cracked,but probably would yield under centrifugal forces that exceed the wheel's strength to hold together,and cause a lot of vibration.

You are aware that "crush rolling" is a well used technique industrially,for example, for forming threads on wheels for thread grinding. That technique sounds pretty dangerous,too,but it works every day in countless factories.

 

[george wilson]

Post deleted by me because it was not understood as a joke(though I did use 3 smiley faces.)

 

[pdentrem]

A surface grinder does make such a nice finish, doesn't it.