how to mount grinder sanding disks, advice please

[happyhero]

Hi I have a 4 1/2" grinder and I had some sanding disks with it that I bought seperately a long time ago. The other day I wanted to rough up or key some paint work in the bathroom and thought the grinder with the sanding disk would be great for that. That is when I realised you should have some backing pad to support the disks (they are like a very hard sanding sheet material, don't know if it is some sort of paper or what it is).

Anyway I bought a rubber backing pad which comes with a little metal threaded disk to sandwich the sanding disk but I am not 100% sure as to how it should be mounted, ie the grinder has 2 removable metal disks, one which sort of keys into the drive bolt and the front one which is threaded and would tighten on to say a cutting disk.

I found you have to remove the front one obviously to leave some thread to mount the rubber pad etc, but I then found I could mount the rubber pad and partner disk with the back keyed disk still in place or alternatively without it.

So do you take both disks off the grinder or leave the back one on, to use the rubber pad and its partnering threaded disk?

You may think why am I asking such a basic question, well it is because I found that when fitted with the original grinder backing disk in place, the sanding disk is well above the guard clear to spin, but when you remove both the original grinder disks and use the rubber and partner disk that the sanding disk virtually touches the grinder guard edge, or is it meant that the guard should be removed for these type of disks, which I am thinking sounds doubtful.

Any help/advice appreciated.

 

[wingcoax]

If the discs are moulded to roughly the same shape as the grinding wheels then they should just fit onto the rear metal "keyed" disc and be secured with the front "nut"disc. You do not need the backing.

 

[Jasonb]

You need to leave the keyed disc in place, fit the rubber backing disc, then the sanding sheet and finally the cone nut that came with the backing disc, you may need to push this down to depress the sanding sheet enough to start the thread.

The reason for leaving the keyed disk is that has the 22mm boss in the middle that the rubber backing needs to fit onto to keep it concentric.

These are not flap wheel type sanding discs so you do need the backing rubber/plastic.

 

[happyhero]

Hi Jasonb, I think what you say makes sense and yes I did have to push down a bit to get the thread started.

Using them this way they ride high over the guard so I suppose you leave the guard on but just ignore it, ie you are not using the guard to catch sparks as you would with a normal grinder disk for example?

 

[Trazor]

Most people remove the guard when using the flexible fibre discs.

It's main use is when you use hard discs or cutting discs.

I'm not a health and safety nut, but wear safety glasses, you only have one pair of eyes.