3M ROLOC backing pad

[enrare]

What is the correct size ROLOC backing pad to use with 3M 2" Bristle brushes, Scotch-Brite pads and sanding discs? I ordered from eBay a bristle brush combo pack which came with one brush each grit and a 3M backing pad. The backing pad in the kit is about 1-5/16" diameter (don't have part #) and dosn't look like it offers much support for the 2" surface conditioning pads and sanding discs. I know the backing pad needs to be a bit smaller than the discs so it dosn't get chewed up, but with my backing pad there is no support for the outer 1/4" of the pads/discs. When I look at some of the pics in 3M literature it looks like the backing pads extend out closer to the edges of the pads and discs.

 

[PT Doc]

What is the diameter of the 2" discs? I would start with 2" then if you wear it down, put a 1.5" backing pad to get more life out of the deal.

 

[enrare]

What is the diameter of the 2" discs? I would start with 2" then if you wear it down, put a 1.5" backing pad to get more life out of the deal.

The bristle discs are 2" diameter. Just went out to garage to try it out and the edges of the brisle disc roll upward and brstle disc sort of "flattens" out as RPM increase on die grinder. They don't seem to work very well when this happens compared to lower RPM and they more or less hold their shape. Don't know if this makes since or not, but right now I'm NOT impressed and sent a message to the eBay seller. I looked at some 3M Roloc vids on youtube and on all their set-ups for bristle discs, conditioning pads or sanding disc the backing pad is just a tad shy of the edge of the discs.

 

[rcjoy]

My 3M 2" Roloc backing pad is 1.75 inches in diameter.

The "3M" logo is molded on the top of the pad, along with an "H" that indicates the "hard" version.

 

[enrare]

Update: I ordered the 3M backing pad #05539 from Amazon. It is 1-13/16" and supports the 2" Bristle Discs much better, thou the bristles still spread out at 20,000 RPM and the disc flattens out, but not near as bad as when using the smaller 1-5/16" 3M backing pad sent in the Ebay combo 3M bristle disc kit. I think the smaller backing pad supplied in the kit is probably to be used with the 3M 1-1/2" ROLOC products.

The 05539 backing pad does have an "H" molded in it and the smaller one has an "M"