Abstract: The present invention is an apparatus and a method of operating a grinder for chipping and shredding material into waste, the grinder including a generally cylindrical drum having an exterior surface with a plurality of pockets formed into the exterior surface. Within each pocket, at least one of a plurality of bits are removably positioned, with each bit having a base securable into the pocket providing an upper cutting edge portion of each bit that extends above the exterior surface. Each upper cutting edge extends outward in an arcuate curving shape from each side of the bit, forming a self-sharpening sharp outer edge for each side of the bit. Each pocket and removable bit has a center line that may be angled off-set with respect to a center line of the radius of the rotor drum, providing protrusion of the leading cutting edge of each bit above the exterior surface so that the leading cutting edges of the plurality of bits are placed in contact with the material to be chipped and shredded.