Let's begin by saying I bought all the diamond wheels, and they were all perfect, but I bought 3 "scotch brite" wheels; 240 grit 600 grit and 1000 grit (also multiples wool felt wheels), the 240 was totally horrible, the center hole was not in the middle, I spent money to have all of them fixed at a machine shop, and they tried but did not succeed, the 600 and 1000 are still not good, so I had to anchor the grinders as for the wool felt wheel was also not center, the 240 grit was replaced by Cli...