If you want these things to last more than 3 minutes then you certainly can't use them over a corner. I barely push the orbit and if the fibrous web catches on the edge it breaks and ruins these discs very quickly. I seem to have about 10 broken discs that I wrap around scrap wood for odd angles and sanding because they break so often. Also, pads that don't break don't seem to perform as well as they should. Mirka should be at the top of the grinding hill but the quality is not at all what I was hoping for. I've literally had more success and durability with Home Depot Diablo pads. Damn