A cautionary tale.

[DavidA]

My grinderette is a Bosch PWS 600.  A nice machine that I have had for years.  It is (nominaly) a 4.5 inch grinder.

We have a similar machine at work,  and we obtain the 1mm cutting discs from the local engineering supply shop which is just around the corner.  I have noticed lately that the discs seem a tighter fit than they used to be,  but they still go on with a bit of wiggling.

As I had almost run  out of discs at home I bought five from this shop (at £1 each) and put them in storage for later use.

Now,  when in Aldi a few days ago I noticed they were selling similar discs at ten for £3.70 or there abouts;  so I bought a pack and , again,  added them to my stock.

Today I needed a disc, so tried to fit one of the ones from the engineering supply;  it wouldn't fit over the spigot.

These discs are labeled 'Norton (Saint Gobain) Vulcan' and are made in poland.
The dimensions state 115x1.0x22,23  and also 4 1/2" x 3/64" x 7/8"

They can be pushed onto the grinder spigot,  but you will have to pry the finished disc off with a screwdriver.

So I pulled out one of the Aldi discs.

They are labeled  'Workzone'
Diameter 125 mm,  Thickness 1.2 mm,  bore 22.33 mm.

These fit nicely on the spigot,  BUT,  and this is the point of this message,  They are  too big to fit inside the Bosch safety guard.

I almost did something very stupid.

I reasoned that , as they were only two or three mm too big,  I could run without the guard until they had worn down a bit then re-fit the guard.

I even got as far as removing the guard and   fitting a disc to see how it would work out.

But seeing that this slitting disc would be running at 12,500 rpm withing half an inch of my hand restored common sense.


I intend to make another guard that will accomodate the discs.  At that price they are too good to pass on.

So if you buy some of these discs,  and they wont fit your grinder, DO NOT REMOVE THE GUARD.

DON'T DO IT.    It just isn't worth it.

Dave.

[dsquire]

David

Good plan. Safety is something that you never want to take a discount on.   

Cheers 

Dom

[NeoTech]

Even with the guards on.. never ever hold the damn thing with one hand in the handle... it can unthread itself, spin around itself on the force of the spinning disc.. and dig it self into your wrist..




2 weeks later

[DavidA]

And I bet that was even more painfull than it looks.

Makes me shiver just to look.

Dave

[vtsteam]

Man you had some bad days with that grinder. Shirt on fire, and cut arms. I'm sorry that happened to you!

A woman sculptor I knew back in the seventies got her hair caught in one -- I think it was a 7 inch grinder -- the 4.5's didn't become popular until more recently. Cut into her skull and almost killed her She was hospitalized for awhile. I've been wary of the things ever since. The smaller ones now make people feel perhaps too comfortable around them, since they have less of a noise and scare factor than the big ones and cam]n be held in one hand. I treat them the way I treat a chainsaw.  (I was a tree climber for several years in my more risky youth). Two hands always, arms out in front, body braced.

Dremels are similarly innocent seeming tools, and meant to be held in one hand. I think about what I'm doing very carefully while using them.

[NeoTech]

Ooh those large grinders is scary as hell. I have one taking 250mm discs. that thing scares the hell out of me.. Good for cutting I-beams and such with though. Really need to hang on to it though.

[75Plus]

David, would it be possible to make an adapter so that the 10 Aldi disks could be placed on a bench grinder and reduced in diameter with a wheel dresser? That might be easier than making a new guard.

Joe

[chipenter]

Wait until it's stopped some of them take longer that you think , I was in a hurry to pull off a piece I was grinding , just brushed the slowing disk went though the glove just grazed my hand but it stung like crazy .

Jeff

[vtsteam]

I suppose they could make a retractable shield -- like a circular saw has. You'd have to pull to open it and it would need to be spring loaded. Best if it was on the side handle. As soon as you let go of that handle it would close.

[DavidA]

Joe,

It probably would be possible to do that,  But you would have to do it with every disc.
If you make a larger guard then you only have to do that once.

Dave.

[DavidA]

VT,

Too complicated,  but I like the idea.
 By making a bigger shield I only have to undo one screw to change over.  Plus,  If these discs turn out to be half decent then my stock will last for quite a while so I won't be changing the shield very often.

Dave.

[75Plus]

Joe,

It probably would be possible to do that,  But you would have to do it with every disc.
If you make a larger guard then you only have to do that once.

Dave.

David, I meant doing all 10 at the same time. It would be like dressing a 12mm width wheel.

Joe

[vtsteam]

VT,

Too complicated,  but I like the idea.
 By making a bigger shield I only have to undo one screw to change over.  Plus,  If these discs turn out to be half decent then my stock will last for quite a while so I won't be changing the shield very often.

Dave.

I didn't mean for you to fabricate one, David, I meant that they ought to be as standard on grinders as the swing guard is for a circular saw. And it would be no more complicated than those

A lever attached to the swinging guard, and a spring. Pull the lever to the left hand side grip and hold both together. Grind.

Let go of the lever, guard closes off the front. The usual fixed guard would remain.

They haven't sold circular saws without guards in my living memory. Well, obvious from the photos above, a grinding wheel is a circular saw without the scary looking teeth. No friendlier to flesh though.

I'd make them removable so people could injure themselves in the usual ways -- one handed grip, disk spins after trigger is let go, loose cord, etc. Choice is important