I have an adjustable speed polisher/grinder and also an adjustable speed grinder and both have a 5/8-11 arbor that I would like to use them to do some sanding and paint removal.

I have a ton of Self Adhesive Discs(PSA and non-PSA as well) and I need to find a 5" or 6" backing pad with a 5/8" female hole. Finding these with a 1/4 male is no problem, finding them with a 5/16" is no problem, but neither of those do any good.

Can anyone point me in the direction of a place that sells such an item ? I've tried the websites of Grainger, Fastenal, Milwaukee, Bosch, Makita, Dewalt, and have not had any luck. They sell a backing pad that is meant to be used with those sanding discs with a hole in the middle.

I'm pretty desperate to find something, so leads are appreciated.