# Grinding Wheel Safety



## instock (Nov 17, 2012)

I just got my first angle grinder and I'm trying to figure out how to use it without hurting anybody. My goal is to grind off a bunch of sloppy mortar where somebody tried to repair cracks in the foundation wall. The cracks are 1/8 inch and they put half inch thick mortar over them (and made no effort to smooth it out). 

What's the difference between to $40 diamond cup wheel and the $4 grinding wheel? 

Should I take the guard off the grinder? That seems dangerous, but I can't figure out any other way to get it flat on the wall.


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## griz (Nov 26, 2009)

instock said:


> *I just got my first angle grinder and I'm trying to figure out how to use it without hurting anybody.* My goal is to grind off a bunch of sloppy mortar where somebody tried to repair cracks in the foundation wall. The cracks are 1/8 inch and they put half inch thick mortar over them (and made no effort to smooth it out).
> 
> *What's the difference between to $40 diamond cup wheel and the $4 grinding wheel? *
> 
> *Should I take the guard off the grinder? * That seems dangerous, but I can't figure out any other way to get it flat on the wall.


Difference between the two is $34 dollars.....

The guard thing....be VERY careful......

Why not hire a Mason to clean the mess up?....:thumbsup:


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## cdkyle (Jul 12, 2009)

griz said:


> Difference between the two is $34 dollars.....
> 
> The guard thing....be VERY careful......
> 
> Why not hire a Mason to clean the mess up?....:thumbsup:


40 - 4 = 34 ?:laughing: Ditto on the be careful.


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## Rockmonster (Nov 15, 2007)

For smoothing something out, the cup wheel is the way to go......you're using virtually the entire grinding surface of the wheel, and stock removal goes quickly, and it's fairly safe, but pretty dusty. The guard won't do a lot when used like this, but it doesn't hurt......

If you're using the _edge_ on a grinding wheel (disc), you are ALWAYS safer with the guard on.....generally, the guard won't limit the depth too much, it's usually the size of the wheel you use.....when you start using larger diameter wheels, it can start to get cumbersome......

Just a tip, though I've never _seen_ it happen.....a friend who has a stoneyard said that an employee of his was working without a guard, and a piece came off the wheel, and embedded into his thigh about an inch....... could be quite a hassle.


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## CarpenterSFO (Dec 12, 2012)

Be careful, and move slowly. Check that whatever wheel you have is rated for the speed of the grinder. Eye protection.


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## Kniggit (Apr 11, 2013)

CarpenterSFO said:


> Be careful, and move slowly. * Check that whatever wheel you have is rated for the speed of the grinder. *Eye protection.


 Needs repeated, made that mistake...once...scared the bejeezus outta me


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## instock (Nov 17, 2012)

Awesome. I'll go ahead with the cup then. Somebody told me the Bosch rep was just trying to make a commission when he sold me the cup. 

The disc actually seems pretty useless, then. What would be a typically application for that tool? 

I did a little practice grinding and that thing is a beast! I'm definitely putting on all the PPE I can find.


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## Inner10 (Mar 12, 2009)

instock said:


> Awesome. I'll go ahead with the cup then. Somebody told me the Bosch rep was just trying to make a commission when he sold me the cup.
> 
> The disc actually seems pretty useless, then. What would be a typically application for that tool?
> 
> I did a little practice grinding and that thing is a beast! I'm definitely putting on all the PPE I can find.


Don't forget a dust mask.


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## Seven-Delta-FortyOne (Mar 5, 2011)

Wear safety glasses, earplugs, dust mask, and work gloves. After all, you're grinding concrete chips at 11,000 RPM.

Get a MASONRY grinding wheel, not the metal one.

Go slow, hold it at an angle, leading edge on the work, keep the guard on, and grind it down. And use the damn side handle. :thumbsup:

Don't grind the brick away, that pisses customers off. :laughing:


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## Seven-Delta-FortyOne (Mar 5, 2011)

griz said:


> Why not hire a Mason to clean the mess up?....:thumbsup:


Prolly cuz he wants to learn to do it himself. :thumbsup:


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## Seven-Delta-FortyOne (Mar 5, 2011)

Sorry. Just re-read your post. You were talking about a diamond cup wheel.

I was referring to a depressed center abasive grinding disc. Depending on how much you have to do, the abrasive discs are a lot cheaper.


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## instock (Nov 17, 2012)

Seven-Delta-FortyOne said:


> Sorry. Just re-read your post. You were talking about a diamond cup wheel.
> 
> I was referring to a depressed center abasive grinding disc. Depending on how much you have to do, the abrasive discs are a lot cheaper.


I'm still confused about this part. I thought the purpose of the depression was so you could put the grinding disc flat on the work surface without grinding the lock nut. But when I tried that, the lock nut still stuck out a little bit. Tough to get a smooth surface like that.


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## Seven-Delta-FortyOne (Mar 5, 2011)

instock said:


> I'm still confused about this part. I thought the purpose of the depression was so you could put the grinding disc flat on the work surface without grinding the lock nut. But when I tried that, the lock nut still stuck out a little bit. Tough to get a smooth surface like that.


Yea, mine does that, too. That's why I just hold it at a slight angle.


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## JBM (Mar 31, 2011)

I have a metal floor vent duct taped to a shop vac for weird situations that make dust. Have someone hold the vac if possible. Makes a difference inside a cellar with so so ventilation im guessing.

Ditto on the glasses of coarse.


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## heavyc (Jul 2, 2013)

Hilti actually makes a grinder that has a vacuum male adapter fitted in the guard configuration. And a self cleaning vacuum that attaches to said grinder. Truly a dust minimizer to the next level. One super set up for interior applications. The vacuum periodically thumps the filter internally dropping particulates in the collection bin. Very pricey set up. But as we all know silica prevention is the cutting edge of masonry safety.


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## S.U.M (Apr 17, 2013)

Here is Hilti Heavy C is talking about, Home Depot rent them but don't sell them, might rent one to see how it goes,


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## heavyc (Jul 2, 2013)

S.U.M said:


> View attachment 100320
> 
> 
> Here is Hilti Heavy C is talking about, Home Depot rent them but don't sell them, might rent one to see how it goes,


We also have the 4" grinder set up the same way it's a little older. We buy directly from Hilti and are loyal to them which we receive perks and special incentive buys. Our punch guy keeps tight grip on these. He has the formal title of Quality Control Resolution Technician. Never had to use his services but floating in the field on some T&M jobs we pick up I was impressed by the performance of these tools.


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## JBM (Mar 31, 2011)

I tried to look for the grinder @ Hilti and I couldnt find it. Does anyone have a purchase link for that?

Im using the Bosch one right now and its good and all, but im looking to buy another one.


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## dom-mas (Nov 26, 2011)

Are you planning on grinding the mortar off the brick??? Don't do that, you WILL damage the brick. Wash it off instead, use acid or a surekleen product


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## tenon0774 (Feb 7, 2013)

dom-mas said:


> Are you planning on grinding the mortar off the brick??? Don't do that, you WILL damage the brick. Wash it off instead, use acid or a surekleen product


:thumbsup:

...and/or a brass brush cup wheel for the grinder, after you have let the acid "work" for a while.


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