5" grinder backer

[gzig5]

I picked up a nice pneumatic grinder at a swap meet a couple months ago. Runs well with a lot of torque and has a 7/8" bushing on the nut. Came with a 5" 36 grit pad on it which is all warped. I just picked up some 24 grit pads at HF and want to use a backing plate with them so I can lean on them a bit but control it while grinding welds and such. Seems all the phenolic plates have a step in them which I don't think these pads are going like getting pulled down in the center when the nut is cinched up. I really need a flat plate, or am I going about this wrong.
Grinder is a commercial version of this

These are the pads I plan to use. They don't have adhesive or velcro, nor do I want them for this use.

and the backers that I can find.

 

[toolmanmike]

The step is to keep the nut below the sanding surface. Without the step, the nut is exposed and can damage the surface you are grinding.

 

[motorpirate]

we always just stack up 5 or 6 pads..
then you can change them out without walking back to the bench.

 

[Syleng1]

Just a worthy note as both above are correct.
Watch your knuckles on those grinders. They have a tendency to take skin along for the ride as there is no guard and you are focusing on the work not your hands.
Don’t ask how I know. Lol!

 

[toolmanmike]

And, those grinders run close to 20,000 rpm. Match a backing plate with the rpm. They are like a hand grenade when they explode.

 

[gzig5]

The step is to keep the nut below the sanding surface. Without the step, the nut is exposed and can damage the surface you are grinding.

I understand this part about the nut sitting down in the depression, but I don't see how these stiff grinding disks are going to flex down into that depression under the nut. I was thinking that these phenolic backers might be designed for adhesive pads and I'm going about it wrong. I've yet to find a picture of this type of backer being used with a coarse disk, or any disk for that matter.

 

[Righty Tighty]

we always just stack up 5 or 6 pads..
then you can change them out without walking back to the bench.

Great idea!

And, those grinders run close to 20,000 rpm. Match a backing plate with the rpm. They are like a hand grenade when they explode.

A friend of mine had a cut off wheel explode and hit him in the face. Full thickness laceration down to the bone. He now has a straight line scar from the corner of his mouth to the bottom of his chin. He looks like a ventriloquist dummy.