Abstract: A knife holder for a rotary type wood chipper is in the form of a segment occupying a segmental portion of the proximal side of the cutting disk and extending to a chip slot of an adjacent knife from its associated knife assembly. The knife holder has a hardened helicoid proximal wear surface that faces the logs that are fed into the chipper. Each knife holder is formed of a base plate which removably mounts onto the disk and a wear plate that is replaceably attached onto the proximal side of the base plate. The wear plate is mechanically attached to the base plate by set screws and is also attached by a weld that runs along a peripheral chamfer. When the hardfacing surface on the wear plate becomes eroded, the wear plate can be removed and replaced.