In the pulp manufacturing process, it is required to have a cooking liqueur permeate to the center of the wood as quickly as possible to enable quick and unified digestion. For that purpose, this chipper is designed for laboratory use to make wood chips of unified dimensions, helping prepare various chips containing different kinds of resin. In operation, wood is pushed diagonally against the rotary disc provided with a cutting knife, which cuts off the tip of the wood. Then, produced chips are air-blown upward to the chip screens. Then, the chips are classified through two-step vibrating screens so that complying chips are sent to the chip collector rack and large-sized ones are conveyed upward on a belt to be thrown into the chipper's slot again.