An employee was cleaning and clearing regrind from the area around a large mechanical grinder. The grinder was powered down and locked out with the machine guarding and covering removed. The employee spun the shaft of the grinder by hand to check and see if the shaft/rotor was clear. This caused the shaft to rotate. He then tried to stop the shaft from spinning and his right hand contacted a blade attached to the shaft, causing multiple lacerations to his fingers.