My new grinding setup

not denying the danger...

David Weaver

..of grinders. I've got two 8" high speed grinders that I use for toolmaking that give me the willies a little, and they have cast guards on them. They feel like a catch resulting in anything getting stuck would turn into an explosion.

But, I wonder how much data there is on something like a 6" wheel and really catastrophic or deadly incidents. It seems like the potential is there (wheel with a tip speed around 80-90 feet a second and that can go right for the noggin).

I learned a while ago that this is not a topic that one should search if they're sitting around relaxed, as the pictures and such that come back are horrid.

(I did go to the ER once in the past for metal in my eye, too - but it was literally off of one of those cheap 4x36 bent sanders like they sell at home depot. I will not use anything that spins or involves any kind of impact without glasses on.

I don't use a TS much - the risk there is well known - google monster says 4000 amputations per year.

I can tell you...

Mark Hennebury

Nearly two years ago I had a 4" x 3/8" grinding wheel go ballistic on me. A chunk hit me just left of my nose, blasted open my upper lip, took a chunk of bone with three teeth in it and pushed it into the middle of my mouth. They sewed my lip up in the emergency ward, My face was so swollen that the surgeon couldn't operate inside my mouth to remove the bone and teeth for a week. That was an unpleasant week. I will spare you the photos.

Thanks, Mark

David Weaver

As I mentioned, it's not something I'm willing to risk myself (the guards are on my grinders, and I do one better, by staying out of the "arc of the prop" so to speak, which doesn't guarantee no contact, but it lessens the chance of it happening full speed).

I'm curious, though, when this comes up on forums where people use tablesaws and they account for 8-10 amputations a day. I've had one grinder catch on a 6" grinder, and it just resulted in the item and the rest getting mangled (the wheel was undamaged and I was, again, standing out of the "arc of the prop"). When I was a kid, I got hit in the face by a baseball twice and had two kids that I was playing with same, but they lost teeth permanently - not looking to compare results with that, just looking to understand how much of the damage from wheels has parity to what we're doing vs. large industrial wheels which have killed people with regularity for centuries.

Re: not denying the danger...

Joe Fleming

I heard from a pro woodturner from England that in order to use a grinder over there, you need to be certified because of the danger. Allan Batty was the source.

Re: Don't know what frequency

Larry Clinton At Frankfort, (Central) Indiana

an issue occurs! I was an Engineer for a large company and was in the tool room frequently. We had several surface grinders, 3 or 4 bench grinders in that area. We also had 3 or 4 in the maintenance shop. In my own shop I have 3 bench grinders, 1 Baldor 8" pedestal grinder and an ancient (but very accurate) manual Brown and Sharp 6 x 12 surface grinder.

In the near 40 years of employment I NEVER saw a wheel explode. I have seen chunks broken out when a tool was caught between the tool rest and the wheel but the chunk stayed there.

Obviously it does happen - just wonder how often, I always felt the guard was to keep metal dust / shards/ sparks from hitting the operator.

Me neither...

John in NM

But I did look it up on OSHA's website out of curiosity. Searching for both "grinding wheel" and "abrasive wheel" produced 227 reported incidents of all types (not just fragmenting wheels).... since 1984!

I'm sure the actual incidence is much higher than that (two workplace accidents in a shop I worked for, both serious ones, did not show up in the OSHA database). How much higher? Who knows? 100x? more?

At 100x that comes out to something like 614 per year. Seems very high for bench grinders, high even if much heavier industrial grinders like surface grinders are included. Seems low if angle grinders are included.

I have had exactly one catch with a small (1/2 HP) bench grinder. To my pleasant surprise, the piece that came out of my hands went right out the un-connected vacuum port on the back of the shroud. After that I kept the tool rests adjusted as the regs state - within 1/8" if I remember correctly. The wheel drag had caused the part to pivot around a rest too far out and that was the "catch". Rests adjusted correctly or not there at all is now my practice

Accidents like Mark's are horrific, and thankfully, much more rare. I have to wonder if they were more common when I assume grinding wheels were less well made, say pre-1950s?

Re: Don't know what frequency

William Duffield

If you think about it, the guard serves two purposes: protection from explosive shards, as discussed here, and also to decrease the chance in the first place that the wheel will be struck by something that initiates the crack.

If you work in a one person shop, you will probably know if there is a possibility that you struck it hard enough with something metal to damage it, but if in a large shop, you never know what some gorilla has done, shrugged his shoulders and walked away from the problem.

When I start my grinder, I always immediately walk to the side and well out of the way of potential shrapnel flight paths, until it has come up to speed. I'm also working on replacing my wheels with steel core CBN wheels, to further increase safety.