Technical Angle grinder etiquette

Cut off wheels are great for coping beams and channels. Now,, if I could find 4” that’s opposing rotation

 

A few years back I purchased a Metal Demon saw blade from Diablo for my Bosch Skilsaw. Best thing I ever did if you need to cut sheet steel into smaller pieces. Good up to 1/4". Chips fly everywhere, so best to be in an open space.

 

All this talk reminded me of something you need to keep in mind. I worked around this stuff for many years. My eye Dr. told me I had miniature pieces of metal in my eyes and if I ever needed an MRI of my head to refuse as the magnetic field would rip the metal out of my eyeballs. SO when I had a stroke in 2013 they wanted to do an MRI and I had to refuse it. I NEVER thought that scenario would actually happen.

 

Ditto on the Metal Demon Diablo Blades. Great for most automotive use as long as you have the room to maneuver and are not obstructed with inner supports, etc. Available depth for the blades travel is the biggest drawback.
I have more than a dozen tools or methods of cutting metal but it seems that an angle grinder with a cut off wheel is the "go to" tool more than not. I've got 4 or 5 of them set up for different uses.Very versatile and fast but still dangerous. I got my share of battle scars and respect the hell out of them and wear the proper safety gear most of the time but did not always. Be safe out there and use the "ounce of prevention" rule.

 

Like using any high speed tools, shit can happen.The same can be said about the humble drill, I’ve seen a few guys over the years with the old large electric hi torque drills, drilling larger diameter holes and coming to grief when the drill bit bites and sends them for a ride.
40 yrs of working in fab shops has taught me a few things, also we work a lot safer nowadays, I’ve seen a lot of disc burns and worse over the years.
I personally don’t like wearing heavy gloves when using a grinder, either grinding or using slitting discs, strange, but to me I feel safer holding a grinder with my hands. I like using a guard and glasses though, also the slitting discs designed for cutting stainless are much safer.
Accidents do happen but you can’t fix stupid!

 

Almost 3 decades in the fabrication field. Never grind with a cut-off disk, and let the disk cut. Don't stand on it and burn through the steel. If you just use the weight of the grinder and let the disk cut, the disk will last longer, less tendency to heat up the disk and have it fail aswell. The rest has been talked about. Wear gloves and be prepared to have the disk cut through them. If your cutting and welding stainless steel, wear respirators. The body can't get rid of stainless like it can ferrous metals. Also TIG welding stainless is suppose to make you limp dicked.

 

I havent seen anyone mention it, so:

aside from the great advice to use a face shield (I invariably hold it the first time in a way that throws grit in my face) buy a battery grinder, like an 18v milwaulkee or ryobi. and buy extra batteries. dont buy the monster ones, a regular one will do.

the battery right angle grinder does not have the torque to shatter a cut off disc. when it binds it just... stops. same with a cup brush catching, same with a grinder disc making the tool jump out of your hand. the battery ones also have dead man switches where "jump out of your hand" = "tool turns off".

my metabo 120v 6" grinder is a monster. I can grind with a flap disc all day if I want, and when I have long cuts in sheetmetal like slicing off a bed side that is my go to, but for literally everything else I use the cordless ryobi. I cut a LOT of heavy duty things, pedals, bias bars, steering columns, u bolts on rear axles, leaf spring hanger bolts, I even cut a piece of train track. whenever the disc would bind the motor just stops. I check the disc at that point and if its missing a chunk I replace it.

and repeating: use a face shield, $24 for a good 3M one. use good cutoff discs, 'cardboard' freight does not sell good cutoff wheels.

 

I never use an angle grinder with a cut off wheel. For that I use a small air powered cut off wheel. I cut my intended path first so there is a groove to follow, then cut it deeper and deeper until I am through it. I have never had one blow apart in many years of using this method.

 

Almost 30 years of grinding and cutting with a 4.5" grinder, I'm guilty of almost never using the shield and rarely use goggles or gloves. The only time I hurt myself was because of a faulty extension cord that was not even mine : it cut the power to the grinder as I was cutting, when I moved the power got restored, I wasn't expecting that and the grinder jumped out of my hand, I only had 5 stitches on my leg.
Very rarely do I use it with one hand, almost never without the handle and never do I hold the part I'm cutting : best way to bind the cut-off wheel. When I feel it's not safe i.e. close proximity or chance of binding, I use a reciprocating saw or a 2" cut off if room permits it. I also almost never cut with the disc spinning toward me, when I do I especially hold it tight.
Always be aware of your environment because the sparks will set on fire everything that is flammable, protect painted parts and glass as the sparks are hot enough to imbide themselves into glass and ruin in no time a windshield.

 

They are all dangerous. Use the guards, practice disk hygiene, use face masks, everything we know we should do but sometimes don't. My experience is one I bet none of you even considered possible. I was making a chair out of laminated plywood (similar to one in photo). As you can imagine it took a LOT of sanding with a 36grit disk. I was sanding along with my 7" grinder with an official rubber backup disk when the disk exploded. It broke into the usual 3 pieces that disks do when they explode but I could only find 2 of the three for a couple weeks. Then one day I looked at the hollow core door between my wood shop and paint booth and there was the rubber wedge impaled through the two layers of thin Masonite on the door about head-high. I left it there for years and even sold he place with it there. I always wanted to glue it permanently in place with Bondo but never got around to it.

 

Back in 2016 i had a 5"angle grinder with a thin cut off disc get the better of me. I always felt i had good skills an an understanding of these tools. Never let it get over center as this causes kick back and even if you are holding the handle it can attack that hand, thats what happened to me. This is the less graphic pic. JW

 

WTF!!!!

 

In my young and dumb days, I had one of those old THOR 9" grinders (you know the kind, weighs about 500lbs). I got 14" chopsaw discs for free, so the old Thor became dual purpose go to tool. It would cut and grind through anything from sheet metal to 12" I beams. A new wheel would take the skin off my knuckle on the trigger finger till it wore down a bit. Even made a 10" handle so I could keep a better grip on the thing. If I chipped the disc, the damn thing would take off like a helicopter. I'd just grind down through the chip to get rid of the vibration. Had a few shatter, but escaped intact. Looking back, I realize that I was the luckiest sob on the planet. Still have it, but it's clamped, and guarded now. Use it like a table disc sander.

 

Any pictures of this clamped grinder?

 

A cut off wheel is a saw not a grinding disk, grind so sparks are going away from you, score the material don't cut thru, flip it over score the other side, never twist the grinding disk or put a side load on it. wear shades or a goggles, when you have both sides scored enough put the piece in a vice and bend the top half back and forth til you have 2 pieces, then head for the bench grinder and clean things up and you'll be set. Jw

 

Oh my, did you have any ligament or tendon damage?

 

Thumb and finger bones 75% cut through and yes, tendons were cut. It almost came out the palm and i didn't really feel it happen. The angle grinder hit the wall with force and bounced back an nearly got me again.
I can post up the just after it happened pic if anyone wants. JW

 

Have a 9 inch that scares me couple of 4 inch not so much. 2012 was cutting a paver with the 9 inch, guard on and wearing safety glasses, grinder exploded into pieces, disc was fine but cut off my finger, piece of the grinder hit me in the face just under my safety glasses. Still knocked out my eye, broke the iris and lens free and had to be removed. At least still got the eye. Picked up my finger and got it sewn back on. Now I wear my old welding full face helmet when grinding.

 

I have used cut off wheels many times over many years.
You must respect the fact that they are very thin and
will not take forced pressure to hurry a cut. In the nuclear industry we often use them. The optimal
tool for this is a Matabo brand cut off tool. It appears
to be a typical grinder. The difference is in the retaining
nut that fixes the cut off wheel to the spindle. The
spindle nut has a spring loaded feature that lets the
disc slip rather than launch itself at you or shatter.
I have found the key to successful cutting is to let
The disc cut at the speed it was designed for. Using
a light but firm pressure will allow the wheel to cut
smoothly. I like to make a light pass to mark the cut and go back over the piece repeatedly. We recently
cut a half inch thick stainless beam flange on a taper some eleven feet long using a matabo tool with 6 inch
slicer wheels. It took about 3 wheels for each cut. hot,
dirty and spark intensive for sure. It proved to be the most effective way to make these cuts. I also use the
smaller wheels with an air angle grinder for sheet metal on my car projects. Using them gingerly has proven to give me the best results.
Just what works for me.

 

There is nothing like sitting in ER watching blood shoot from the wound in your hand waiting for the doc to remind you to keep the shield, be careful, you know the rest, 11 stitches, large area between thumb and forefinger with no feeling.

 

Good video on grinder safety tips and tricks, long but worth it


Sent from my iPhone using H.A.M.B.

 

Future blind guy.

 

He is using the Health and Safety regulation squint. JW

 

If this doesnt get anyone's attention that reads it, there is no hope!

 

Guess how we used to cut corrigated iron roofing sheets in the 1970's in Australia ?
Big Black & Decker circle saw with the blade put in backwards . Rip right through

 

That is still common practice today in NZ ! JW

 

"That is still common practice today in NZ ! JW"
And back home in Arkansas!

 

I have had a few blow up on me, and normally failure time happens right when you think, "oh Ill try to go real light this other way just to get that last little bit" And then it grabs and goes boom... Cutoff wheels always shoot the sparks back at me. Disc is always pulling away from you, this minimizes the ability for it to blow up if its not the "el cheapo supremo" disc.

Safety tip is to wear welding gloves when using one, keeps your hands pretty safe, got a few cuts into the leather on mine but none of the cuts ever went into skin... face shield is a good suggestion for about anyone, they are cheap just cumbersome to use under a dash...

 

if you have cutoff discs exploding it is because you have twisted it in the cut. it is that simple. either that or I am just very lucky. I bet I have used 400 of the Harbor Freight cheapo cut off wheels and have never had one explode. I've even used them when they were damaged.

let the blade do the cutting. never force anything, never twist anything they are made for straight cuts. never have your face in line with the cutting wheel. if all you can see is the edge of the disc you are asking for trouble as if anything breaks it is flying straight towards you.

if you want to do something dangerous and scary use a 9" shrinking disc on a 10 pound full sized grinder. no guard anywhere, then you have to set it down upside down while still spinning to cool your hot spot. more dangerous than lawn darts or those clacker balls they uses to sell.

 

A few years back HF switched from blue to green label. I had great luck with the blue ones but the green ones gave me lots to worry about.

The big shrinking disc is very scary to run,
Now I let off the trigger while still on the metal till it stops.