This may be old news to all of you out there, but i stumbled across a new and easy way to get cut off wheels/grinder wheels, off of your grinder. Ive got the typical 4" grinder, and have long lost the arbor nut and back plate thingy. I now buy the wheels that have the arbor nut already on the wheel, which if not put on tight, can tighten up while in use, and become a booger to get off. After destroying many wheels trying to get them off, this morning i grabbed my trusty rubber mallet, and tapped it right off while holding the lock. So far this morning ive changed wheels serveral times without cracking one of them. Hope this helps at least one of you out there, because it sure is helping me.