Abstract: In the production of ceramic plates, the wet uncured extruded clay substrate is cut into plate shaped pieces by vertically reciprocating punching knives disposed about at least a portion of a plate shaped area. A pressure plate is mounted within the punching knives and vertically movable against spring forces therewithin so as to maintain downward pressure against the substrate material during the plate cutting operation. Chamfered plate edges are formed by special chamfering knives adjustably mounted at the edge of the pressure plate. The chamfering knives depend from the pressure plate and extend outwardly into contact with and inside wall surface of the punching knives so as to avoid undesirable burrs at the plate edge and also to permit convenient adjustment of the chamfering knives to compensate for wear.