Me again - This may be a no brainer and easy "what's it" for you'ze guyz, but I can't find the answer:

What's the meaning of the different types, 1, 3, 27 grinding discs? Those are the 3 types I've seen so far. My Angle Grinder says type 3 on it, so is that the type discs I have to buy and why?

In case anybody's wondering why I'd buy power tools without knowing about them, I didn't - Inherited them from my past on dad

Hi, So do the discs bolt on?  Spin on?  3M twistlock?  How large is the grinding face?  Do you have a disc now?   If you do, take it with you to a good hardware store and compare.   I wouldn't think the 3 on the grinder has much to do with disc type.  Discs should just have coarse, fine, extra fine, or grit ##s.    Let us know what you find.

Here's a link showing the differences:
http://www.emitsuya.com/technical/WheelShape.aspx

If you google grinding disc types, then go to images, there are a lot of decent results.

ok, alot I needed to know apparently. Thanx for trying to help guys. This might be a lost cause:

Black and Decker 6101 Type 100 Disc Sander:

http://www.ereplacementparts.com/black-and-decker-6101-type-100-disc-sander-115-volt-parts-c-4167_4300_12193.html

The backing piece #28 is 6 5/8" across, part/nut #29 is 5/8's, and fits into rubber disc. Though replacement parts says it's a type 100, as you can see, my plate says type 3. That's what I was wondering about, or if it even matters. I'm sure I'll find something that works by bringing those attachments parts with to ace, etc.

*Part/nut #29 is 5/8", fits into rubber disc, part #27, which is 4 1/2" across outside diameter

*The backing disc, part #28, is 7/8" across the inside hole diameter

Type 1 is a rectangular section thin wheel - standard item for most angle grinders

Type 3 is similar, but the wheel tapers in thickness towards the edge - most Type 1 grinding discs (as opposed to cutting discs) end up looking like a type 3  - however, I have never seen a type 3 used on an angle grinder - could it be the type of angle grinder, rather than the disc... Possibly a type 3 could be used for special applications, e.g. if the angle grinder is mounted on a stand, and used for a specific operation such as chain saw sharpening

Type 27 is a depressed centre disc - both grinding and cutting discs can be of this type..

Cutting discs are not designed for sideways pressure, and should never be used as grinding discs.

I find flapwheels invaluable for sharpening edge tools, but you must grind away from the cutting edge. Replaceable sheet discs on a flexible backing plate are also good, and generally cheaper, but do have a tendency to fly apart of the rim is damaged. e.g. catching it on a sharpened edge..

>my plate says type 3. That's what I was wondering about, or if it even matters

When on the name plate, type ususlly refers to the generation of the tool design, it will matter in that case for replacement parts, it is a different version of the tool.
(Sort of like putting a letter suffix on the model number, eg mdel 10B would be a little different than model 10A )
It *might* not matter for generic things like the washers and nut for the disc , they usually don't change the sizes of that stuff...

The other really important thing with grinding tools is the speed, always make sure whatever disk/wheel you put on it is rated for *at least* the speed printed on the nameplate....

>Cutting discs are not designed for sideways pressure, and should never be used as grinding discs.
After having several of them fly around the shop and try to make swiss cheese out of my face, I am of the opinion they are best used to keep my coffee cup from leaving rings on my bench ;P

Quote from: rusty on February 17, 2013, 07:27:48 AM

>Cutting discs are not designed for sideways pressure, and should never be used as grinding discs.
After having several of them fly around the shop and try to make swiss cheese out of my face, I am of the opinion they are best used to keep my coffee cup from leaving rings on my bench ;P

  Just yesterday I cut a bar of hardened tool steel 3 1/2" wide and almost an inch thick in the middle. One side tapers radically making it almost a a pyramid shape. I sliced it with a cutoff disk, did not disturb the temper of the steel, and it hardly took much diameter off the disk either.
  Of course, when I started with these disks, I promptly sent myself to the hospital for 6 stitches!
They bite if you screw up.

    They are the kind of tool that I am afraid won't be on the market forever. You can screw up and hurt yourself any number of ways with them. Perfect lawsuit material and some greedy lawyer will class action them out of business one day, at 40%.

  But meanwhile, they do work nothing else can do. Fast and gentle on the work as long as you guide them in a very straight line.   
So enjoy them while you can.

  I love flap disks too, btw. Fast and pretty, you can get a pretty decent finish right from the disk with practice. 
The little grits hurled at lightspeed can go all the way --through-- an eye though,
  so never fail to wear your face shield.
  Another great invention they will take away from us one day.
yours Scott

I've already had both accidents happen scott, so if I didn't know before, I do now. Metal sliver in eye while car body grinding. Worked at a boat prop manufacturing shop. Disc broke while grinding welds. Wish I would have known the grinder becomes a bucking bronco from the instant unbalance. Took a nice chunk out of my leg. (doubt I could have stopped it from happening if I did know) Well I think I'm good with all the info -  thanx again tool guys