Abstract: Chipper for chipping of wood into chips suitable for defibrizing. The basic construction of the chipper consists of a horizontal shaft supported by a frame structure as well as of a blade disc mounted on the shaft in a vertical plane. The blade that performs the chipping is mounted on one side of the blade disc or, alternatively, on both vertical side faces of the disc. The blade projects from the side face of the blade disc perpendicularly and runs on the side face of the blade disc as a continuous narrowing spiral starting from the periphery of the blade disc. As the cutting edge of the blade becomes more distant form the periphery of the blade disc, it simultaneously also becomes more distant from the plane of the blade disc while following a screw line. The length of the chips to be chipped is determined by the spiral pitch of the blade edge, i.e. by the relative distance between two radial points on the blade edge.