Abstract: A press for the production of particleboard from a preformed mat of wood particles and a suitable binder has spaced apart frames aligned one after the other and first and second parallel press platens movable toward and away from each other. The improvement comprises motivating structure connected between the first press platen and at least some of the frames for moving that platen to an extended position toward the second platen and against the preformed mat to thereby close the press. Dimensionally stable support structure positioned between the press frames and the first press platen maintains that platen at its extended position while preventing bending or arching thereof. Actuator structure connected between the press frames and the second press platen moves that platen toward the first platen and against the preformed mat while maintaining the second platen substantially parallel to the first to thereby press the preformed mat.