Abstract: A machine for shredding various materials, such as blocks of plastics, wood residues, cardboard packaging, building materials and so forth, comprising a rotor constituted by a cylindrical roller and a plurality of shredding teeth, arranged in respective slots, which are provided in the surface of the roller and lie on radial planes which are perpendicular to the axis of rotation of the roller, the shredding teeth comprising cutting elements constituted by plates and blocks for fixing the plates and cooperating with stationary teeth arranged in a comb-like arrangement, the plates being arranged directly on the slots provided in the surface of the roller and the blocks being accommodated in cavities shaped like seats for a key, which are formed in the surface of the roller in line with the slots and lie at right angles to them, the blocks being fixed by means of screws so that they can be removed from the seats and protruding from the slots with a portion that acts for the plates as an element for abutment and