EMPLOYEE STATED HE WAS HOLDING ONTO THE ROOF BOLT BEING INSTALLED WITH HIS HAND ABOVE THE PLATE.THE BOLT WAS BEING PUSHED INTO THE HOLE USING THE DRILL STEEL WRENCH POSITIONED BELOW THE PLATE. WITH THE PLATE BEING LOCATED BETWEEN THE WRENCH HIS HAND BECAME WEDGED ON THE CRADLE AS THE DRILL HEAD WAS BEING RAISED. THE PLATE SPUN OUT AND UPWARD CONTACTING HIS RIGHT WRIST ABOVE GLOVE.