Grinding Wheel Failure

[Rich Aldrich]

I was sharpening a 5/8" bowl gouge this afternoon using a varigrind jig.. The gouge slipped off the face of the wheel, I think and there was a loud bang when the grinder stopped and jumped back. The wheel chipped out on both sides and the lag bolt holding the grinder to the bench top pulled out.

The wheel was about 2 months old and saw a small amount of use. It is a Norton Gemini, 120 Grit. I dont think the gouge caught, probably the varigrind jig.

I am not sure how I let the tool slip off the face. Maybe the varigrind 2 is safer?

[Steve Kubien]

There is nothing I fear in my shop more than my grinder. Yes, I include tablesaw and chainsaw in that consideration. Too many things not under my control with grinders. Gald you are ok.

[John Keeton]

I am betting the gouge doesn't look quite the same either!!:eek: Glad it wasn't worse.

[Rich Aldrich]

Steve, Thanks. I learned to treat the grinder with a lot more respect - after this happened. It happened so fast and no time for pucker factor until it was too late.

I think this wheel is too soft. It grooves very easily and is really meant for carbide. I bought it from one of our vendors. I told him I wanted a Norton 3x, but this is what he brought and I accepted it without looking into it.

That being said, I should not have let the tool slip. The Varigrind 2 has a guide so you cant let the tool slip off to the side. Maybe it is somewhat safer.

[Rich Aldrich]

John, the gouge looks fine, in fact, I used it to rough turn a bowl afterward. I think the varigrind jig took the brunt of the damage, but I cant find much for damage on it either. It was almost like the edge of wheel shattered and caught jig.

If you look a the pictures, the edge ground on something for about 1/4 of a turn until it shattered the edge. I dont know why the other side shattered, also, but it might be just collateral damage.

[David E Keller]

Glad you're OK.

[Michael James]

double ditto on no harm to you! I bought the wolverine because my attempt at the homemade one was just not rigid enough. I saw the warnings out there that this could happen. Universal shop safety precautions at every power tool is my motto. I realize murphy's law applies to everything to touch out there in the shop.

[alex carey]

Like Steve said, the grinder is the only thing in the shop that scares me. I've heard some really bad stories involving them also.

Nice to hear your still intact.

[Cathy Schaewe]

I have the vari-grind 2. What happened to you has happened to me twice, but I wasn't using the vari-grind either time. I'm now fairly religious about using it, after losing most of a fingernail after the second 'explosion.' I think it's a good jig, for me at least, because I had absolutely no sharpening experience. I do think it makes the grinder safer.

[Allen Neighbors]

You're a fortunate man, Rich! Glad you didn't get hurt. Sometimes I have to check myself... I get into a hurry sometimes when I'm grinding, I want to get back to turning...

[Jonathan Harvey]

Wow thats scary. I don't know why but I always take my face shield off while I'm grinding, I guess I just need a bit of a break from wearing it all the time and grinding is the only chance I get but never again. WOW sorry it happened but I guess we can all learn from it, so thanks.

[Bernie Weishapl]

Glad you are ok. I fear my grinder more than any tool.

[Ronald Blue]

The wheel was damaged from impact or pressure. The wheel didn't fail. I have experienced/witnessed wheel failures before. Worst case scenario they fragment like a bomb and can do a great deal of damage. Based from the photos with both sides of the wheel sustaining damage while the center remained intact indicates the wheel wasn't the cause. As others have stated the good thing is you only received a scare from this. A faceshield is a good idea to wear during grinding operations. Just my two cents worth. Take it and a $1.75 and get a cheap cup of java somewhere.

[David Hostetler]

While I am not happy with my Norton white wheels... But that so far has been because of the lousy bushings. The stone itself seems okay. I am not sure about the model you have though. From what I have seen and heard, you want the white wheels for HSS tools... The softer stones are mostly for carbide....

Swap to the right wheels. If you don't have them yet, get some decent bushings from McMaster Carr...

So far, no problems with the Varigrind...

[Neil Strong]

I also remove my turning face shield when I'm grinding... so I can wear my high impact rated face shield while grinding. Only ever had one wheel let a piece go and that was enough to have me treat the grinder as the most life threatening bit of equipment inside my workshop.

Glad you also survived your incident, Rich.

.....

[Steve Schlumpf]

Rich - glad it wasn't any worse than it was and - most importantly - that you were not injured! If you still have the stone when it's time for our next turning club meeting - bring it along for show & tell and I'll bet that you'll get 40 different reasons (from the 25 attending) for the failure!

[Rob Cunningham]

Rich, glad you weren't hurt. I've been a tool & die maker for almost 30 years, and have seen my share of grinding wheel mishaps over the years. From small ones like yours to full blown wheel failure. The grinder deserves a lot of respect.
The green wheels for carbide do not hold up well on HSS.
Check your grinder bearings and shaft before mounting a new wheel. Make sure the shaft runs true and there is no play or damage in the bearings.
Always wear safety glasses and stand off to the side when starting a grinder.

[Matt Newton]

Glad you're OK. About 3 weeks ago I wasn't so lucky. I was sharpening a gouge with the varigrind and was in a hurry (mistake number one). The gouge slipped off the wheel and the middle finger of my left hand came into contact with the wheel. By the time I pulled my finger away, I had lost a good chunk of skin between the first and second knuckle. I think part of the problem was how I was holding the jig. It's all healed up now. (My finger and my ego):rolleyes:

[John Hart]

Rich...I am very glad that you aren't dead or maimed. I agree with some of the others here that the grinder is the one tool that is the most scary.

You're really close to it...it seems harmless....it can explode.

You're reminding me that I need to finish my belt-sander-sharpener thingie. :)

[Faust M. Ruggiero]

Rich,
While I am sure you had the sharpened edge of the tool well above the center line of the wheel, perhaps part of the body of the grinding jig was only slightly above. Perhaps the body of the jig touched the wheel just above center and was forced backward by the circumference of the wheel itself. It's scary to think one split second of misjudgment can cause a catastrophe. When I researched grinding jigs I chose the Sharpfast system because the tool cannot slide off the edge of the stone. However, if you remove the tool from the jig without removing the jig itself, the jig can still get trapped between the wheel and bushing the jig pivots in. I am always careful to lift the jig from the bushing because left on the base it can vibrate forward and hit the stone. The VariGrind II now offers the same safety factor with additional adjustments.
Glad you didn't get hurt. Change your underwear and try again.
fmr

[Rich Aldrich]

Thanks for the comments, guys. I always wear my face shield when grinding. It has been drummed into me from our safety meetings at the paper mill. I had my shop apron and gloves on, but a short sleeve shirt. I am on the fence about a long sleeve shirt, just like the gloves, I could get pulled into the grinder. The shirt might help for fragments if one blew up big time.

I am convinced that the jig did the damage - it may have been below the center line when it came in contact with the wheel, but it seems like there may have been previous damage or defect to cause this failure.

I talked to the company where I bought it. They had never sold this type of wheel before and wanted my feedback. I told them I didnt expect anything because I wasnt so sure it isnt my fault, but they want to take a look at the wheel. His supplier might replace it anyway.

I ordered a replacement Norton 3X from Hartville Tool today. I went with the 80 grit, K type. If the other one is repalced, that would be kind of nice - 80 on one side and 120 on the other. Awe shoot, that means I will have to make a decision on which one to use.:rolleyes:

[Rich Aldrich]

Rich - glad it wasn't any worse than it was and - most importantly - that you were not injured! If you still have the stone when it's time for our next turning club meeting - bring it along for show & tell and I'll bet that you'll get 40 different reasons (from the 25 attending) for the failure!

I will wait to give it back to the sales guy after the meeting so we can show people. I am in no hurry since I ordered another today from Hartville.

[Rich Aldrich]

I have the vari-grind 2. What happened to you has happened to me twice, but I wasn't using the vari-grind either time. I'm now fairly religious about using it, after losing most of a fingernail after the second 'explosion.' I think it's a good jig, for me at least, because I had absolutely no sharpening experience. I do think it makes the grinder safer.

Cathy,

With the vari-grind 2, can you even get close to the wheel with the jig near or under the centerline? I suspect it can't. I think I had a major slip and put the tool under or close enough to the centerline like Faust mentioned in his reply.

The Varigrind 2 is something I am seriously considering.

[Rich Aldrich]

Rich,
While I am sure you had the sharpened edge of the tool well above the center line of the wheel, perhaps part of the body of the grinding jig was only slightly above. Perhaps the body of the jig touched the wheel just above center and was forced backward by the circumference of the wheel itself. It's scary to think one split second of misjudgment can cause a catastrophe. When I researched grinding jigs I chose the Sharpfast system because the tool cannot slide off the edge of the stone. However, if you remove the tool from the jig without removing the jig itself, the jig can still get trapped between the wheel and bushing the jig pivots in. I am always careful to lift the jig from the bushing because left on the base it can vibrate forward and hit the stone. The VariGrind II now offers the same safety factor with additional adjustments.
Glad you didn't get hurt. Change your underwear and try again.
fmr

Faust,

I will check into the Sharpfast system. I had not heard of this one before. The more I think about it, I think you are right. It was probably a big enough slip that the jig did end up near or under centerline and bam.

Update: I just checked out the sharpfast system. This is what I am looking for. Thanks for the advice. That is one slip that should not happen again. Now I just have to ask my better half about funding.....

[Faust M. Ruggiero]

Rich,
Don't overlook the Versagrind II. It is new to me but so far, I really like it. It is locked in at the base, adjusts for different grind angles and shapes so it accommodates bowl and spindle gouges. With any of them, don't lose your focus for even a second.
Be safe. Woodworking is more fun that way.
fmr