Found this on a website today...

Broken wheel

Nasty! (but not gruesome)

Some interesting feedback comments though, for example using a cutting disc for grinding, or using a wheel once it was worn down to threads.

The bit that I don't understand is that my grinder has a shield covering half of the wheel. This half is always between me and the disc, mainly so I don't get covered in sparks. If a disc is going to shatter, then won't it head away from me? Or at the very least bounce off the workpiece before it gets to me?

Don't get me wrong, I'm not just relying on that shield, I still wear a full face shield, overalls and welding gloves. But it does seem like as well as PPE a few basic positioning rules would also reduce the risk?

From the deep grooves in the side of the disk, I'd guess its been twisted while 'deep' into the material - they can snatch then and disintegrate. 9" grinders are a lot more dangerous than 4.5s.
I've had a couple of the 1mm *115 discs let go, and they have so little mass the bits don't really do anything thank goodness, so a good reason to use them.

Regards
Hugh

Yeah I had a chunk of 1mm disc hit my forehead, didn't even leave a mark. I always wear eye protection but I've seen full helmets at the local welding shop, will get one. One thing i don't understand is how few people use ear protection with grinders.

Benzine - yep, me too. I use an ear defender - faceshield combo that I can't recommend enough, labelled as 'Oregon'
No only is it comfortable and quiet, but the ear muffs hold the thing securely at all head angles.

I use my older motorcycle helmets for a lot of things, tree pruning, filling compressed bottles, etc.

I've watched (as have we all) the professionals out there cutting steel, concrete, whatever with large (huge) and small angle grinders. No eye, ear, whatever, protection. Real men clearly...

I always wear eye protection after being terrified by one of the old timers at work when I was 17! Happily there grinding with no glasses, old timer came over and gave me some advice, being a cocky young bleeder I gave him a mouthful back. He told me to hold my hand out, and then proceeded to remove his glass eye and pop it in my hand! He lost his eye grinding! That moment is imprinted on my brain and still sends shivers down my spine!

I've had one hit me in the head before, hurts a bit.

But the disc in that picture has clearly been abused, and not used correctly in the first place.

A friend of my fathers nearly severed an arm when using a petrol powered disc cutter with he wrong type of disc which shattered . After loads of operations he still hasn't got full use of his arm