Cheap Discs and Angle Grinders

[mjac]

While there are cheap grinding/cutting discs out there I find most accidents with grinders are the result of improper use/technique. I’ve had good and bad cutting discs come apart before and it’s always the result me doing something I shouldn’t have.

The technique may have been lest then absolutely perfect, obviously had the rotation in the wrong direction if the kickback came at me as someone has pointed out, but it was not sloppy or careless, there was no side pressure, piece was very well secured, wasn’t rocking grinder across the surface, didn’t have the disc buried in the cut, it was on the surface, didn’t go straight down on the vertical leg, stayed on the outside and will admit if technique was absolutely perfect the kickback might not have happened. But as of right now, I firmly believe, that if during that very cut I had a top quality disc in that grinder, Walter, Pferd, Lennox, that kickback would not have happened. Might be wrong.
Did the disc disintegrate then kickback, or did the disc just kickback and disintegrated went it grabbed my pants leg?

Thanks
mjac

 

[mjac]

I use Benchmark and Hercules flap wheels mostly. But I absolutely wear jeans, boots, a carhartt jacket, and a face shield when I grind. It's not at all a big deal to throw some PPE on, and it's a lot more convenient to have all my fingers and toes attached to my body where they belong.

I could use more safety gear, got the full face shield and goggles, could use a leather apron. I like my chest and legs too…

Thanks
mjac

 

[mjac]

And bonded discs/wheels have an expiration date for a reason.


@mjac can you post a pic of those Black & Decker cut off discs?

Kind regards,
Olli

Have to dig them out of the trash, threw them all away out of disgust, about 15 of them. If there is anything embarrassing on them, I will pretend I couldn’t find them. But I will say this, the Warrior discs I were using that night and the one I finished up with after getting hurt were bought at almost the exact same time and stored under the exact same conditions.

Thanks
mjac

 

[mjac]

Get out of my garage! Yes that's my routine, face shield - proper pants - usually a welding coat. As for extinguisher, I suggest you track down a pressurized water or CO2 extinguisher. The ABCs filled with MAP will make a real mess of your space.

Can not laugh at safety guys after what happened, I am lucky I am still here…

Thanks
mjac

 

[mjac]

Yes and No.
There are two separate companies.
-The global Flexovit brand is owned by SG.
-Flexovit USA (Angola, NY based) operates as a separate entity, a privately held company. They manufacture exclusively in the USA and only distribute in the Americas (NY, CA, Mexico, Canada).

Not familiar with Flexovit at all, will have to find out about them. For the time being ate going to try Walter, Pferd, Lennox and Makita…

Thanks
mjac

 

[PCustoms]

@mjac is using a grinder relatively new to you?

 

[mjac]

@mjac is using a grinder relatively new to you?

Not an every day use, but can handle it. It is easy to blame the disc though…

Thanks
mjac

 

[mjac]

@mjac is using a grinder relatively new to you?

I could change my mind, but right now I firmly believe that if during that cut I had a top quality disc, Pferd, Walter, Lennox, that kickback would not have happened. I am going to try and duplicate that cut using some Makita discs today and see what happens. Will get rotation right this time so any kickback will be forward, not back at me…

Thanks
mjac

 

[M.Brane]

When grinding if at all possible stay out of the plane just like chain saw rules.

 

[PCustoms]

I could change my mind, but right now I firmly believe that if during that cut I had a top quality disc, Pferd, Walter, Lennox, that kickback would not have happened. I am going to try and duplicate that cut using some Makita discs today and see what happens. Will get rotation right this time so any kickback will be forward, not back at me…

Thanks
mjac

I can't remember, after it attacked you was the disc broken?

 

[mjac]

When grinding if at all possible stay out of the plane just like chain saw rules.

My biggest mistake was having the rotation wrong where a kickback came back at me instead of forward. This kickback was so wild, it didn’t matter what plane you were in, it could have gotten you.

Thanks
mjac

 

[mjac]

I can't remember, after it attacked you was the disc broken?

The disc was absolutely shatteted and the shaft of the Metabo was twisted into my loose fitting nylon athletic pants, so tight, it stopped a very powerful Metabo motor but it was still grinding me until I managed to pull the plug, could not find the switch. I believe the disc shattered with contact on the pants.

Thanks
mjac

 

[Nobody-named-Olli]

Have to dig them out of the trash, threw them all away out of disgust, about 15 of them. If there is anything embarrassing on them, I will pretend I couldn’t find them. But I will say this, the Warrior discs I were using that night and the one I finished up with after getting hurt were bought at almost the exact same time and stored under the exact same conditions.

Thanks
mjac

Really not looking to embarrass you, just really interested in the discs. Reason being, and I think it has been pointed out before, I don’t remember when I, for the last time, saw any Black & Decker consumables for sale. And out of curiosity I googled a bit, and all I found was some eBay UK seller, offering some “new old stock” of highly questionable age to be actually used. Something that might actually be really great for a collector to put next to a Black & Decker grinder of the same age in some “time correct” show & tell garage, but not something I would ever use.

Really just interested in the discs, and I’m honestly happy your injuries weren’t worse and you’re still around to tell the story!

It’s really not for the sake of ”being right” or any Schadenfreude at all.

Kind regards,
Olli

 

[alwaysFlOoReD]

My biggest mistake was having the rotation wrong where a kickback came back at me instead of forward. This kickback was so wild, it didn’t matter what plane you were in, it could have gotten you.

Thanks
mjac

This so much. Always, always use the grinder so it is pulling away from you.

 

[PCustoms]

Really not looking to embarrass you, just really interested in the discs.

Same here.

I've had bad discs, and abused discs too. When they explode it's usually pretty immediate on contact with the cut.

A grinder is probably my least favorite way to cut material BTW

 

[mjac]

Really not looking to embarrass you, just really interested in the discs. Reason being, and I think it has been pointed out before, I don’t remember when I, for the last time, saw any Black & Decker consumables for sale. And out of curiosity I googled a bit, and all I found was some eBay UK seller, offering some “new old stock” of highly questionable age to be actually used. Something that might actually be really great for a collector to put next to a Black & Decker grinder of the same age in some “time correct” show & tell garage, but not something I would ever use.

Really just interested in the discs, and I’m honestly happy your injuries weren’t worse and you’re still around to tell the story!

It’s really not for the sake of ”being right” or any Schadenfreude at all.

Kind regards,
Olli

SCHADENFREUDE…i think I am in trouble

They have and still do sell Black & Decker cut off discs in the United States. But my point is this. These Black & Decker discs may be older then I realize, BUT, the Warrior discs I was using that night and finished up with after getting hurt, were bought at almost the exact same time as the Black & Decker discs and stored the exact same way. The Black & Decker discs kicked back, the Warrior discs did not kick back doing the same cut and finishing the cut the Black & Decker discs did kicked back on…

Thanks
mjac

PS: I will look for the discs…

 

[American Locomotive]

I have had good luck with Pferd and Carborundum brand discs. The Carborundum Carbo Gold discs are some of the best I've used. They don't fray or blow up. They're a saint-gobain brand, so probably the same as Norton.

Also, I really have a hard time accepting that you care about safety when you admit you don't run guards on your grinders. Been using angle grinders for 15+ years now, everything from heavy fab to body work. Guard stays on, and I just rotate it to the position I need.

I also find it insane you wear nylon pants when grinding. Those things are so flammable and melt so easy.

 

[mjac]

This so much. Always, always use the grinder so it is pulling away from you.

Damn near got me killed, so yeah, I think it might be important…

Thanks
mjac

 

[zendriver]

if there was "kickback" involved, is this a problem with the disc or user error?

 

[mjac]

Same here.

I've had bad discs, and abused discs too. When they explode it's usually pretty immediate on contact with the cut.

A grinder is probably my least favorite way to cut material BTW

That really is the big question, what happened on contact with the metal. What caused the violent kick back. Did the edge of the disc fray and caught the edge of the metal on the down cut then shattered twisting into the pants or did the disc shatter in the metal causing the kickback…

Thanks
mjac

 

[L.Cheapo]

3M, Lennox, Pferd, Walter, Makita, which is your choice?

Thanks
mjac

3M, always.

Not disparaging the others, I just know if I buy something from 3M it will work properly, last longer than most, and be as safe as possible. Also easy to find from any industrial supplier, some box stores, and certainly online. Sure it might cost more, but I'll take that over the alternative.

 

[Nobody-named-Olli]

SCHADENFREUDE…i think I am in trouble

They have and still do sell Black & Decker cut off discs in the United States. But my point is this. These Black & Decker discs may be older then I realize, BUT, the Warrior discs I was using that night and finished up with after getting hurt, were bought at almost the exact same time as the Black & Decker discs and stored the exact same way. The Black & Decker discs kicked back, the Warrior discs did not kick back doing the same cut and finishing the cut the Black & Decker discs did kicked back on…

Thanks
mjac

PS: I will look for the discs…

Appreciate the effort! Thank you!

Have you seen the copyright date on those discs you posted the picture of, that are being sold? 2005 … This makes them, give or take, 21 years old …

Typical expiration for bonded discs is between 2 and 3 years after manufacturing/ and ideally purchase. The last ones I bought mid 2025 are good through 2028.

Again, this doesn’t have to be the reason for what happened, but I think it’s at least noteworthy.

Kind regards,
Olli

 

[mjac]

I have had good luck with Pferd and Carborundum brand discs. The Carborundum Carbo Gold discs are some of the best I've used. They don't fray or blow up. They're a saint-gobain brand, so probably the same as Norton.

Also, I really have a hard time accepting that you care about safety when you admit you don't run guards on your grinders. Been using angle grinders for 15+ years now, everything from heavy fab to body work. Guard stays on, and I just rotate it to the position I need.

I also find it insane you wear nylon pants when grinding. Those things are so flammable and melt so easy.

Going to try Pfred, Walter, Lennox and Makita for now, some others have been suggested.

i will have to reexamine not using guards, but this is my position. A guard helps prevent shards snd sparks from hitting you, but it does not prevent kickbacks, the most dangerous element of an angle grinder and the one I am obviously most concerned about right now. In my opinion a guard makes a kickback more possible because it interrupts your sightline to where you might put a disc in a position where it is more likely to cause a kickback. I want to see what I am doing and have that visual feedback so adjustments can be made. Compensate by using premium goggles, premium full face shield and now, a leather apron. If you do not think safety is of concern, look at the picture in the OP and realize that could easily have been much, much worse.
Okay, nylon pants were not such a good idea ( but they are so darn comfortable) need a leather apron. Afraid to find out how much they cost.

Thanks
mjac

 

[mjac]

Appreciate the effort! Thank you!

Have you seen the copyright date on those discs you posted the picture of, that are being sold? 2005 … This makes them, give or take, 21 years old …

Typical expiration for bonded discs is between 2 and 3 years after purchase. The last ones I bought mid 2025 are good through 2028.

Again, this doesn’t have to be the reason for what happened, but I think it’s at least noteworthy.

Kind regards,
Olli

Did not look that closely, just grabbed one of the pictures of Black & Decker cut off discs for sale and took a screen shot of it. There were numerous others. But you are right, these discs in a grinder turning 11,000 rpm can be so dangerous you do not want a disc beyond the expiration date spinning in that grinder making contact with metal.

Was this Schadenfreude?

Thanks
mjac

 

[Nobody-named-Olli]

No, not at all.

Kind regards,
Olli

 

[mjac]

3M, always.

Not disparaging the others, I just know if I buy something from 3M it will work properly, last longer than most, and be as safe as possible. Also easy to find from any industrial supplier, some box stores, and certainly online. Sure it might cost more, but I'll take that over the alternative.

Must agree. 3M across many product lines is a superior choice, not familiar with their discs though…

Thanks
mjac

 

[mjac]

No, not at all.

Kind regards,
Olli

I know my Scadenfreude…

Thanks
mjac

 

[Bert_]

The saying I always heard,

"Cut towards your buddy not towards your belly (leg)"

"You can always get another buddy but you can't get another belly (leg)"

Failure is always a possibility. I don't care how high quality of stuff you buy.

 

[alwaysFlOoReD]

I've modified my guards when necessary. Even to the point there is only a half inch left. I had a disc pick up the tail end of thin strip of metal and did the cat o nine tails on my hand. I was very lucky to get 17 stitches and no permanent finger damage. That had no guard...

 

[mjac]

if there was "kickback" involved, is this a problem with the disc or user error?

What I keep going back to, same cut, even finished the cut that the kickback occurred with a Warrior disc, no kickback, two new Black & Decker discs, violent kickback. Only used the new Black & Decker discs because the last Warrior disc was about 1/3 worn down. After the second Black & Decker kickback, finished the exact same cut with the worn down Warrior disc.

Thanks
mjac

 

[mjac]

The saying I always heard,

"Cut towards your buddy not towards your belly (leg)"

"You can always get another buddy but you can't get another belly (leg)"

Failure is always a possibility. I don't care how high quality of stuff you buy.

I am going with sparks toward you, not away from you…

“Failure is always a possibility” and it can be catastrophic. Got to get leather apron.

Thanks
mjac

 

[Bert_]

Even the most expensive disc out there could kick back or bind up under the wrong circumstance.

Buying a better disc maybe lessens the chance. How often do you want to slice your leg? Once out of 100 cuts, or once out of 1000 cuts?

Me personally I'm just not going to cut towards my leg!

 

[mjac]

I've modified my guards when necessary. Even to the point there is only a half inch left. I had a disc pick up the tail end of thin strip of metal and did the cat o nine tails on my hand. I was very lucky to get 17 stitches and no permanent finger damage. That had no guard...

Guard would have stopped it? Never considered that, have to take a closer look. I just like seeing what I am working on.

Thanks
mjac

 

[mjac]

Even the most expensive disc out there could kick back or bind up under the wrong circumstance.

Buying a better disc maybe lessens the chance. How often do you want to slice your leg? Once out of 100 cuts, or once out of 1000 cuts?

Me personally I'm just not going to cut towards my leg!

Technique was not bad, in my opinion a top quality disc would not have kicked back.

Cut was away from body and leg, rotation was wrong, causing kickback to come back toward you instead of forward away from you.

Thanks
mjac

 

[mjac]

They have some nice welding aprons at reasonable prices, I thought they were much more expensive. “YESWELDER” looks like a good value. I would be insane not to get one after what happened. Then I could keep wearing my nylon pants.

Thanks
mjac

 

[finn]

The technique may have been lest then absolutely perfect, obviously had the rotation in the wrong direction if the kickback came at me as someone has pointed out, but it was not sloppy or careless, there was no side pressure, piece was very well secured, wasn’t rocking grinder across the surface, didn’t have the disc buried in the cut, it was on the surface, didn’t go straight down on the vertical leg, stayed on the outside and will admit if technique was absolutely perfect the kickback might not have happened. But as of right now, I firmly believe, that if during that very cut I had a top quality disc in that grinder, Walter, Pferd, Lennox, that kickback would not have happened. Might be wrong.
Did the disc disintegrate then kickback, or did the disc just kickback and disintegrated went it grabbed my pants leg?

Thanks
mjac

You didn’t answer a couple of questions brought up earlier.

First, did the grinder have a guard, or not?

Second, did the grinder have the handle attached, or not?

If you were cutting angle iron, it’s almost a certainty that the wheel pinched. I much prefer to use the horizontal bandsaw for cutting angle. Even the bandsaw pinches, but you’re not trying to decelerate a 20000 rpm wheel in that case.

Blaming the disc is easy, but it may have been a casualty of binding from side pressure in the cut, or previous damage, compounded by aiming the grinder in the wrong direction. Just because it worked cutting like that 100 times previously doesn’t mean it won’t happen.

The biggest issue I have with cheap discs is that they don’t last long, so I generally don’t buy them. I won’t grind wearing anything but denim jeans, and heavy weight jeans at that, along with face and eye protection. I also inspect the disc, and double inspect if I put the grinder down “incorrectly”. I’ve broken the little 3” air cutoff discs when they snag while cutting. It’s always from too much side force in the cut, ie operator error.

It takes a conscious effort to not use a cutoff discs as a grinding wheel, too. They can’t handle that.

 

[whateg01]

Technique was not bad, in my opinion a top quality disc would not have kicked back.

Cut was away from body and leg, rotation was wrong, causing kickback to come back toward you instead of forward away from you.

So, which was it?

 

[mjac]

You didn’t answer a couple of questions brought up earlier.

First, did the grinder have a guard, or not?

Second, did the grinder have the handle attached, or not?

If you were cutting angle iron, it’s almost a certainty that the wheel pinched. I much prefer to use the horizontal bandsaw for cutting angle. Even the bandsaw pinches, but you’re not trying to decelerate a 20000 rpm wheel in that case.

Blaming the disc is easy, but it may have been a casualty of binding from side pressure in the cut, or previous damage, compounded by aiming the grinder in the wrong direction. Just because it worked cutting like that 100 times previously doesn’t mean it won’t happen.

The biggest issue I have with cheap discs is that they don’t last long, so I generally don’t buy them. I won’t grind wearing anything but denim jeans, and heavy weight jeans at that, along with face and eye protection. I also inspect the disc, and double inspect if I put the grinder down “incorrectly”. I’ve broken the little 3” air cutoff discs when they snag while cutting. It’s always from too much side force in the cut, ie operator error.

It takes a conscious effort to not use a cutoff discs as a grinding wheel, too. They can’t handle that.

- No Guard ( would not have prevented kickback)
- No Handle, but both hands properly on grinder
- Previous cuts that night, same materiel, same grinder, material fixed the same way, same technique Warrior discs, not a hint of kickback. Last Warrior disc wore down, went with 2 new Black & Decker discs, two violent kickbacks touching the vertical leg being held in vise and 2 leg grabs. With material still in vise from that cut, with blood dripping down the leg, changed to the worn down Warrior disc and finished the exact same cut, no kickback. Picked up, went inside to take a lookie look at how much damage I did. Expecting the worse, not too bad, could have been very bad, even lethal. That is why I say it is the discs. Might be wrong.
- Just looked at some leather welding aprons, they looked nice and were reasonably priced, after what happened I have to get one, “YESWELDER” looks good…

Thanks
mjac

 

[whateg01]

- No Guard ( would not have prevented kickback)

Can prevent other injuries, but I suppose we can wait until they happen to address that.

- No Handle, but both hands properly on grinder

A handle makes a big difference in the amount of control you have over the grinder. You have ahold of it on 2 different axes, whereas holding just the body, even with both hands still allows the grinder to rotate even if you think it isn't happening. So, when a disc does grab, even a little it twists the body in your hands because the disc is off to one side. Then it binds and you get kickback. You said earlier your technique is good. No it's not.

 

[mjac]

So, which was it?

I am not sure what you are asking but the direction of the grinder was away from the body across the top of the horizontal leg of the angle iron with the vertical leg of the angle iron in the vice away from the body. But the rotation of the disc was throwing sparks away from the body which meant when the grinder kicked back it came at the body instead of away from the body.

Thanks
mjac