Safe to use cutoff wheels on angle grinder?

D

DirtyBrad

Joined
Dec 20, 2006
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I'm starting my second knife next week. I did the first with just hand tools to get a feel for it, but now I'm plugging in. I picked up a $40 Ryobi angle grinder today at HD with the thought of using it for rough cutting my blade profile and then for rough grinding the bevels. It came with a few grinding wheels and I also picked up a couple of cutoff wheels.

I have zero experience with angle grinders. While I was reading through the manual, I came across this:

Use ONLY Type 27 depressed center wheels. NEVER attach a Type 1 straight or cut-off wheel to this angle grinder. This product is only designed for grinding and sanding. Use for any other purpose is not recommended and creates a hazard, which will result in serious injury.
Click to expand...

I did some on-line research and saw a couple things. The first is that the guard has to be rated for Type 1. I can't find too much information on this, but it looks like the requirement for that is that it covers 180 degrees, which this grinder seems to do.

The second is that the flange nut shouldn't be conical because it can press the cutoff wheel out of shape, which will weaken it. The flange nut on this one is flat on one side and stepped on the other. The manual shows using it facing one way for certain wheels and the other for others. So, it seems like it would be fine to use flat side facing in.

Oh, and the cutoff wheels I got are marked for metal. They've got a max RPM listed at about 14,500. The grinder's RPM is 11,000.

Based on this little bit I'm able to find, it seems like I should be good to go, but I'm not sure if I'm missing something. I searched this site as well and wasn't able to come up with a hard answer. My apologies if I've missed anything obvious. As I said, I'm a total newbie to this tool. I want to be safe and playing by the rules. If I'm not 100% okay using this grinder for cutoff wheels, I'd also like to return it before I use it on anything.
 
Well...no experience with the Ryobi, but I have a craftsman 4.5" angle grinder that I used cut-off wheels in all the time. The important thing about any cutting wheel used in a hand held tool is to not cause the wheel to flex (by unknowingly changing the angle and torquing the wheel) which can result in it shattering. I always use a full face shield when using it as well.

Just FYI and not intended to be an endorsement.

--nathan
 
Ah, the plot thickens. I didn't realize there were depressed center (Type 27) cutoff wheels, but of course there are. I'll pick up some of those. Maybe the guard position is meant only for that type (although I can't see how having the wheel more inboard of the guard would be a danger).

But I'm left with the warning in the manual about only using the grinder for grinding and sanding. Given that I can use the correct type of cutoff wheel and that my guard seems to provide the same amount of coverage as any other grinder, I'm not sure why I shouldn't use it to cut.
 
if your wheels fit on the spindle correctly and your nut tightens down itll be fine. are the hole cutout for grinding and cutoff wheel the same? does the bottom of the spindle have a ledge around it? but it should be flat side in for cutoff discs. i cut metal/cast iron pipes every day with this set up. if somthing needs to be flipped youll hear it and see it as soon as you turn it on. the wheel will rub against your guard. and do not ever use cut off wheel without the guard. they can splinter and or shatter.
 
Thanks, Nathan. I'll be cutting slowly and carefully. I was actually just looking at face shields. I found a Canadian OSHA report of a guy being killed by one of these suckers. Wheel busted up and a chunk punched through his face shield and did him in. He was using it with no guard, a wheel that was too big for the tool, and a conical flange nut on a flat wheel.

I should also officially absolve any responders from the slightest responsibility for my grisly demise. Hopefully someone recently maimed by following internet forum advice will soon attempt a lawsuit and get laughed out of court. That would be a useful precedent.
 
I have been using them for years for all sorts of concrete, tile, and steel. Make sure you have a metal cut off blade. Don't force and don't bind it, both actions can and will shatter a blade. Wear eye protection and be aware of where your are cutting on the object.
With a round object cut in the 7-9 position, if you let the blade get 12 or above position the momentum of the grinder will take it around the other side if you are not very lucky, which can be dangerous. :eek:
I often cut contours by slowly letting the blade do the work. If you try to force it it is hard to handle and you just wears out the cut off wheel quicker.
Practice, will get you to the point of cutting circles with out screwing up! :D

I guess you already know by your last post but, it must be rated for RPM of your grinder! Also if it doesn't feel right shut it down and take a look to make sure it is mounted correctly. I bought a wire cup one time for my grinder and the first time I fired it up it nearly took the grinder out of my hands. Turns out it was out of balance or could have been the wrong RPM as it was not marked and the store didn't know what it was rated at. Some of the Chinese garbage was the main problem! Anyway I had to take it back.
 
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If you're looking at it wheel side facing up, the bottom of the spindle has a lip that fits inside the hole of the wheel, such that the wheel can't slide laterally at all. This lip is slightly lower than the thickness of the wheel. When the flange nut is tightened with the flat side facing down (toward the wheel), there is no play whatsoever in the wheel.

I assume that if I'm cutting with the wheel vertical, I want the top of the wheel moving away from me, right? To do so, I'll have to have the side handle in my right hand. I don't want to be looking from the blade side, but trying to see where the cut is going from the other side (with the handle) seems like it might be tricky.
 
My grinder is made where I can reverse the handle from side to side depending on the direction I need to get into the material. I usually let the blade rotate into the work, kind of letting it skate across the material to establish the cut and then back into the material to make it cut deeper. It is kind of hard to describe but after you try it a couple of times it will begin to be second nature.
Practice on some scrap and you will see what I am talking about. Above all don't force and don't bind. Those cut off wheels will literally disintegrate into a bunch of little missile pieces! Faster that you can say "What The Sh!4 Just Happened" if you bind one!! In other words it is best not to let the blade get full depth in the cut, use the edge to do the cutting, (less chance of binding)!
 
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Hi Friend,

Those things come with manuals and safety guards? So that's what those were! Although I wear eye, ear, face and lung protection...I take off the guard and cinch down whatever disk will fit in the buggers. Just make sure the disks' shaft hole are the right diameter for your machine. Make note to whether you have a 4" or 4.5" grinder, so you pick up the right size disk. (I still sometimes grab the wrong ones in the store and don't realize it until I go to use them.)

I presently have two grinders. One is set up with a heavy steel wire brush to clean up rusty metal and the flux off weld joints. The other one is used to swap back and forth between cut off and grinder wheels. Next time I come across a machine on the cheap and have a few bucks in my pocket I'll pick it up to further minimize disk swapping.

In addition to working on the right place on the disk (very important and you'll soon get the hang of that) watch where you're throwing sparks. I have heard of more than one fire being started that way. The more you can triangulate with your grip the better control you'll have. You know, things like bracing your elbows against your hips and the like.

Be prepared to get dirty!

All the best, Phil
 
Yes, the handle can be set in one of three positions, left, right top. What I mean is, if my barstock is laying flat in front of me, I want the wheel positioned vertically to cut down into it, right?

So, as I'm looking at it, the left side of the tool has the exposed wheel. I could position the handle so that it's at the top in this position, but I feel like it would be safer to have it opposite of the exposed wheel.

Sorry I'm talking this to death. I think the salient point is that I can get the Type 27 cutoff wheel, which I'll do on the way home today. Thank you again to everyone for your responses. As always, this forum is outstanding.
 
Thanks, Phil. All excellent advice. I have to say I'm looking forward to catching something on fire with my tools.
 
DirtyBrad said:
Thanks, Phil. All excellent advice. I have to say I'm looking forward to catching something on fire with my tools.
Click to expand...

I speak from experience here on two counts:

1) Almost set my shop completely ablaze with grinder sparks.
2) Had a grinding wheel blow up and cause my 5 stitches.

My advice:

Guards are important. Use them.
Watch where you throw your chips, and don't assume because your'e not actively grinding that the danger has passed. I had stopped the grinder 20 minutes before the fire started. It took that long to smolder and build up enough thermal mass to ignite.

-d
 
I will use the guard for sure. I'm missing a piece of finger already thanks to cleaning a meat slicer with the guard off. Hopefully that lesson's reinforced enough.

And I'll just catch one thing on fire to say I did it. After that, I'll be super careful.
 
Phil., unless you are running something like a wire wheel and don't mind a few wires sticking in you, PUT THE GUARD BACK ON. PLEASE. I have seen these things come apart and know a guy who had one seriously mess his thigh up when the disc blew up and he didn't have a guard on. Few inches to the left and he would have been able to hit the high notes. Having said that we used to cut the guards down to about 2/3 of stock and tighten the screws just enough so you could grab the guard and force it around to have it where you wanted it. The new Dewalt guards have a lock so you can reposition easily.
 
I have used an angle grinder for cutting, but my advice is don't cut all the way through. I cut down to the point where my hacksaw could finish the job in just a few strokes.

Smarks ARE going to fly. Clean up the area before you begin. Remove anything remotely flammable (especially sawdust, paper, greasy rags, and so on).

In short, don't be stupid. Also, go slow. Let the grinder do the work, don't push it too hard.

- Greg
 
deker said:
I speak from experience here on two counts:

1) Almost set my shop completely ablaze with grinder sparks.
2) Had a grinding wheel blow up and cause my 5 stitches.

My advice:

Guards are important. Use them.
Watch where you throw your chips, and don't assume because your'e not actively grinding that the danger has passed. I had stopped the grinder 20 minutes before the fire started. It took that long to smolder and build up enough thermal mass to ignite.

-d
Click to expand...

I almost cut the tip of my finger in half when I had the guard removed. They are there for a reason and they don't block your view if you know what your doing! :thumbup:... Watch the movie watchmen and you will fear your angle grinder for a week... i did :eek:

As for the fire. I always stay in my shop for 15 minutes after I finish grinder. Then check it after half an hour and wait at least another 1.5 hours before I close the doors and go to bed.

When your grinding you want to know were your sparks are going and make sure there is nothing flammable there. Loose papers, trashcans, gas, rags, towels, clothes, and anything else prone to fire should be kept out of your grinding zone.
 
My Milwaukee does it all. I even have a diamond cut off wheel for cutting ceramic tile.
 
How is that tile cutting? I assume you can't do it wet, right? Would you consider using it for a full job or is it better for just little stuff?
 
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