I almost died today. Safety with old wheel grinders

Sam Salvati

Sam Salvati

Joined
Aug 6, 2007
Messages
5,060
I almost died today.


I took my old pedal powered stone sharpening wheel and hooked it up roughly to my belt grinder motor, set on the middle speed pulley configuration, it was running smooth and true. I put a piece of steel to the wheel while it was running, I was off to the side not sitting on the seat. If I had been sitting in the seat I would either be in the hospital in a vegetative state from a crushed in skull or laying in a bed with massive blunt trauma, or dead laying in my shop until someone found me. The stone exploded, and when I say exploded I don't mean it came apart I mean it exploded with a bang, broke into 4 main pieces and in line with how it was spinning. 2 small chunks went through my roof, 1 chunk went through my small ryobi wood bandsaw and embedded chunks of stone and the bandsaw itself into the 2x4 shelf beam behind it, another main chunk flew into my KMG motor which was powering the grinder and put a 1/2" deep 2 1/4" round dent into it and broke off the magnet inside and pulverized the wireing box on the front, the other 2 main chunks and small bits went into the wall and pulverized. A split second after it exploded I went running out of the shop, seeing the directions and sizes of the pieces after the aftermath I was lucky I was not hit by a ricocheting piece that could have seriously damaged my body or killed me. In hindsight it did not seem that stupid an idea, but thinking deeper a natural sandstone(?) wheel as compared to the vitrified wheels that run just fine 3 times as fast on my bench grinder was not a smart idea. If you own one of these grinders, do not attempt to motorize it. I thankfully made it through this event unscathed, but it could have been worse in more ways than it could not have.


I am talking about this type of grinder

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Holy smokes! Through the roof! Through a bandsaw!

Amazing that you made it out alive!
Congratulations go play the lottery man!
 
Wow. Holy cow man. I'm glad you're okay.

Do you know how fast was it turning?
 
That was the most unbelievable STUPID thing I have seen on the forums yet

Glad you survived unscathed.
natural pieces of sandstone are not meant to be used as centrifuges, which is the effect that the circumference of the grinding wheel was experiencing. Use rotary tools as they were designed to be used, that includes running them at the speeds they have been designed for. When a flywheel unloads (slang term used by hotrodders is "grenades") they kill people and rip through cars. Glad you were not inline when it blew. Say a prayer to whomever you regard sacred, reaffirm your relationships with your loved ones, and think about them before doing another dangerous tool mod.

-Page
 
Yeah..... Judging from the damage you described it sounds like you could very easily have died or at bare minimum had significant brain damage, though death would be more likely IMO judging from the distance you would have been at.... Glad you weren't hurt. I think we should have you run ideas past several members on several forums BEFORE you attempt anything like this again. You might also need to be supervised....... Not trying to be hard on you but you are a good guy Sam and I'd hate to see you attempt something so risky with little prospect for benefit again...
 
Nathan the Machinist said:
Wow. Holy cow man. I'm glad you're okay.

Do you know how fast was it turning?
Click to expand...

Nathan, I am not sure. If you can calculate the speed, I can give you the pulley sizes and motor speed. it was a 1725RPM motor with a 1" pulley to a 3" pulley on the 5/8ths shaft on the stone, which was about 2ft in diameter.

Thanks everyone for the kind words. There is no supervision needed, I understand my error of judgement. I would please ask this thread to not get into the mental stability of myself (feel free to PM ME on that subject), let it be as a lesson to others not to do this.
 
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Sam,
I'm glad you are OK.

This is a prefect object lesson for those who say...." It isn't a big deal, lots of folks do it."

If you make something do what it isn't intended to do, bad things often happen.

Again, I am so glad you are OK. It could have be tragic.
Stacy
 
Stacy, thank you.

This was not a "It isn't a big deal, lots of folks do it" kind of thing, it was a misjudgement that a natural wheel could handle the speeds of a modern vitrified wheel.
 
I didn't mean my post to be harsh (though after reading it again I can see it is) and I don't think you mentally unstable. I'm just concerned about a good guy I see post on here regularly getting hurt for trying something pretty risky. I apologize if it was too harsh. Just be careful.
 
Wow. Definitely glad you are ok, my friend. We all do stupid things at some point in our lives. It's a wonder any of us live as long as we do. The important thing is that you're ok and that we all learn from this. Heck, when I was young and a bit more dumb than I am now, I flipped a pickup on a dirt road going 85mph and had it come to rest ON my head. Luckily some farm hands came along and used a bottle jack to lift the truck off of my head and I walked (stumbled) away with just some cuts, shredded finger tips, and a Texas-sized concussion. Now I have a true claim to hard headedness.

You, Sam, now have a true claim to being blessed. Praise God you weren't sitting with your head and chest only inches away from that grenade.

Oh, and we're going to need pics of the aftermath.

--nathan
 
3613 feet per minute is the rim velocity I calculated, a modest 60 feet per second(1/2 the speed of a spring powered BBgun) I never took physics, so I don't know the equation to calculate the energy in one pound of rock traveling at that speed, but it's prodigious as evidenced by the shrapnel damage to the shop


-Page
 
Glad to see your ok Sam. Mate as much as there's some conflict over opinions and approaches we all love our hobby and we should all help each other be safe with it.
 
I'm very, very glad that you're unhurt. You already know how dumb it was so I won't say anything about that.

Time to thank you're guardian whatever very sincerely!
 
geeze,i have been thinking a lot about getting a water jet cutter to cut a stone for me for that exact job.i will now be rethinking it.i dont think it was stupid sam,im glad you wernt hurt.i wonder what kind of stone the japanese use and the sheffield cutlers too.,from what ive seen they look white like the sandstone?
look after yourself and go buy a lottery ticket too.
cheers, casey
 
I'm glad you were not physically hurt. I can't even imagine how terrified I would have been.

I'm really glad you posted this. It really helps put things in perspective in the dangers of trying to save money, time, and just cutting corners.
 
Thanks for the number Page.

Nathan, I sure as heck said a few prayers afterwards.

John, opinions are like buttholes, everyone's got one, but it never keeps me from buying a person a beer and if I ever meet you in person you can bet that's what i'll do, despite differing opinions on something trivial as a hobby.
 
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