After looking up the 3in grinder from what I have read in the specs and reviews on it you can't buy the buffing wheels alone also its apparently not variable speed anymore. That is if I am looking at the same grinder you are using. I'm going to the store in the next few days and I will look at what they have in stock. It would be nice to have something that cheap I could use regular greaseless compounds with. If not I will either be stuck with the 6in or possibly looking elsewhere for a 1750 rpm. I'm still not sure.