Angle grinder questions

[kenzo42]

I will be cutting a large LCA grade 10.9 (1/2" diameter) bolt. I'd like to be safe about it since I've heard all the horror stories of angle grinders. I have a Harbor Freight 4.5" angle grinder. A couple of questions:

1) Can I use a smaller cutting disc (3") in a 4.5 grinder?
2) Are smaller (diameter 3" vs 4") disc less likely to explode?
3) Are thicker disc (1/16" vs 1/32") less likely to explode?
4) Can I just use a Dremel instead? If so, any recommended disc?

Any other tips? I will be wearing all the recommended PPE.

Thanks guys.

 

[MFolks]

1. I'd use the size rated for the grinder,
2.Any wheel can explode if spun above it's rated safe speed, or abused(twisted, while doing the cut).
3.Depends on how thick of a cut you're doing, but see #2.
4.A Dremel will go through a few wheels doing this cut & overload the tool, get a good angle grinder, ear plugs & face protection. I've got a Makita, with a selection of wheels & steel brushes, for cleaning, and sharpening mower blades. Still going strong after 10 years.

 

[rlitman]

Disc thickness has little to do with it wanting to explode. Buy QUALITY abrasives (do NOT buy discs at HF), and run them at or below their rated RPM. Metabo, Sait, Walter, Fein are top shelf. Norton is ok, as is Freud. DeWalt is lousy. HF is dreadful.

A 3" disc will be fine in a 4 1/2" grinder. But there's no point in doing that.

Use a face shield and hearing protection. Get a firm grip on the grinder with two hands, and don't force it. It should cut through a 1/2" bolt very quickly. Just go straight in with the disc, and try not to twist the disc in the cut. i.e. Anything that rubs on the side of the disc is bad.

 

[bcradio]

Disc thickness has little to do with it wanting to explode. Buy QUALITY abrasives (do NOT buy discs at HF), and run them at or below their rated RPM. Metabo, Sait, Walter, Fein are top shelf. Norton is ok, as is Freud. DeWalt is lousy. HF is dreadful.

A 3" disc will be fine in a 4 1/2" grinder. But there's no point in doing that.

Use a face shield and hearing protection. Get a firm grip on the grinder with two hands, and don't force it. It should cut through a 1/2" bolt very quickly. Just go straight in with the disc, and try not to twist the disc in the cut. i.e. Anything that rubs on the side of the disc is bad.

DeWalt is just fine... used and abused by many

 

[BK13]

I dunno about DeWalt quality, but I will say that the only discs I have ever had blow up on me were DeWalt. Whether it was from bad discs or operator error, I couldn't say for certain... could be both (but it was probably mostly me). DO NOT put any pressure on the disc in any direction other than parallel to the face of the disc. I'm pretty sure that's why mine exploded, I was bending the disc just a bit. A face shield is probably a pretty good idea. I only had on safety classes and those shards hurt, but did not puncture the skin. Ear protection is a must.

 

[MG44]

Have not used anything but hf discs in 5 years, absolutely no problems on probably sober a hundred discs in varying size grinders

 

[Zeke]

Have not used anything but hf discs in 5 years, absolutely no problems on probably sober a hundred discs in varying size grinders

Me too as the discs are not plentiful at HD and Lowers. Smaller discs are fine. In fact we just had this discussion re table saw and chop saw blades. RPM's will be the same but the circumference travel speed will be less with a smaller wheel. That's simply because there are less inches to rotate with each RPM. Put an over sized wheel on there with more inches around and you will see what I mean.

 

[bwringer]

Have not used anything but hf discs in 5 years, absolutely no problems on probably sober a hundred discs in varying size grinders

Me three.

I've abused the **** out of a couple of $10 HF angle grinders and untold numbers of HF metal cutting discs. Never once had a problem.

Wear some eye protection and go for it. Should take about 5 seconds.

 

[kenzo42]

Thanks for the replies. As far as cutting grade 10.9, should I be looking at the ones rated for "stainless steel" or non-ferrous metals or "metal". There's so many options.

 

[sloppy]

Have not used anything but hf discs in 5 years, absolutely no problems on probably sober a hundred discs in varying size grinders

Same here.. sometimes I will buy another brand as a impulse buy or because I know I will need a extra and I am at the welding supply or something.. But they dont really seem much better and dont last dramatically longer(certainly they dont surpass the cost difference in the extra time I might get)..

The HF cutting wheels are fine..

One HF 4.5" disc will make the cut you describe with no problems.. Face shield and safety glass's gloves are optional some like them some dont..

 

[2drx4]

You're drastically over thinking this. Regular disk will be fine.

Bind and chatter is what causes disks to break, beyond manufacturing defects. Hold the grinder steadily and let the disk do the cutting, don't force it, don't let it chatter, don't let it precess, don't move it into anything that will grab the other side of the disk... 5-7 seconds later the bolt will be cut.

 

[G_P]

Any angle grinder with a cutoff disc should go right through that 1/2" grade 10.9 steel.

 

[NorCalWrenchin]

No disc to explode on a sawzall...

 

[Spareparts]

Keep the guard on, don't know how many small grinders I have seem with the cutting disc on without the guards.

 

[Tejaas]

Keep the guard on, don't know how many small grinders I have seem with the cutting disc on without the guards.

Agreed.
I'll admit that there's some "safety" things I have bad habits about in my shop.... hearing protection hardly ever, eye protection 50% of the time, and I will even admit to running a torch or tack welding in flip flops and shorts a few times...


But angle grinders are ALWAYS respected.

I'd wager that unless your running a 1930's-era sawmill or the like in your garage, the angle grinder takes the cake for "most dangerous" tool.

Always use a guard with cutoff wheels, and matching wheel types/guards at that!


~Tejaas~

 

[BBChevro]

I will be cutting a large LCA grade 10.9 (1/2" diameter) bolt...

You didn't mention if the bolt was "in situation" or just needed to be shortened (held firmly in a vise ).

If the bolt is in an awkwark location, make sure that you have a firm grip of the grinder because it may try to "kick back" if the blade contacts another surface (on the opposite edge of the disc - ie.: - the intended "cutting point" may be at the 2 o'clock position of the disc, but if the 6 o'clock position contacts something else, the tool may want to "travel" in the opposite direction).

Ask me how I know

Like many others have mentioned, you'll cut through that bolt like a hot knife through butter - just use common sense.

 

[PugetDude]

It will take you less time to cut off a 1/2" bolt than it did to post the question- and that's with any brand of grinder or disc.

 

[BK13]

But angle grinders are ALWAYS respected.

I'd wager that unless your running a 1930's-era sawmill or the like in your garage, the angle grinder takes the cake for "most dangerous" tool.

Always use a guard with cutoff wheels, and matching wheel types/guards at that!


~Tejaas~

I'm thinking that it's a tight race with table saws...

 

[Tejaas]

I'm thinking that it's a tight race with table saws...

BEFORE or AFTER the guard is removed to better accommodate actually USING the tablesaw?!?! Haha!


~Tejaas~

 

[BK13]

Good point, though the saw I am most accustomed to is older than I am (mid-'60s Craftsman).

 

[mechanicalmoron]

I wish I had an angle grinder at all - not hatin' on you for having one.

But I think you're overthinking this, I would have used vice+hacksaw to have it cut in less than the time it made you to make this thread.

Thanks for the replies. As far as cutting grade 10.9, should I be looking at the ones rated for "stainless steel" or non-ferrous metals or "metal". There's so many options.

"metal" is probably fine - I don't think it would be horrible to use any of those, though it'd probably not work well and eat the disk.

The real no-no is using non-ferrous metals (and maybe stainless, I don't know) on a normal steel disk - and this isn't just for cutting, also for normal grinder wheels, and on bench grinders, etc.

This is because of the consistency of these metals - they will clog the pores of the wheel, and effectively pack it with metal - causing it to explode.

 

[2drx4]

Keep the guard on, don't know how many small grinders I have seem with the cutting disc on without the guards.

Meh. I have 6 or 7 grinders. I have the guards on a couple and not the rest. Generally you can neither see what you're doing, or actually get the grinder where you want it, if the guard is on it. A 4.5" cutting disk does not have the energy to really hurt you if it shatters. Generally it just feels like somebody threw a small handful of coarse sand at you.

That said, if you don't have the time using one, and are not comfortable with it, you probably shouldn't take it off. And I absolutely won't run the 9" grinder without the guard. There's too much energy in that disk if it breaks.