Angry with myself today. I recently bought a new Jet 8" 1hp 3600 rpm bench grinder to augment my 7" 1800 rpm Baldor. In my haste to get it up and running I made my first mistake, I did not bolt the grinder to the bench. My second mistake was not ring testing the new Norton 3x grinding wheels before installing them. Apparently the 46 grit wheel was damaged and on spool-up it broke in half as it neared full speed. The wheel guard contained the wheel halves but with the sudden stop of the wheels all the stored energy had to go somewhere resulting in the 60 lb grinder jumping off the bench onto the concrete floor. Quit amazing to see. This resulted in breaking one of the cast iron tool rests, cracking the cast iron base and bending the mounting bracket for eye safety shield. Fortunately the motor shaft and cast wheel guards are undamaged. I powered up the grinder with the wheels off and then checked for shaft run out with a TDI. After that checked out okay I put the factory wheels back on and powered it up. So far so good. Hopefully the vendor will replace the damaged wheel. So secure your grinders and ring test the wheels before installing!