A high-quality industrial abrasive made for extended general-purpose grinding on metals, castings, welded joints, rivets and rust. User Tips Use the 415 dressing stone to clean the surface of the grinding stone and restore its original shape. You can also use the dressing stone to create a grinding stone with just the right shape for that special job. For best results, insert the accessory bit all the way into the tool and then back it out slightly before tightening down. This provides plenty of shank for the collet or chuck to hold onto the bit.