Abstract: An apparatus for comminuting materials includes a rotating or stationary ring of knives that is arranged around a chipping chamber. The ring of knives is has a plurality of knife carriers, which are distributed around the knife ring axis in a circular shape, each knife carrier having a bearing surface. The bearing surface is a receptacle for a knife package that is comprised of a knife retaining plate and a slicing knife, and which is held in an operational position at a predetermined angle and a predetermined blade projection by fasteners. The knife carrier has a reference surface, which interacts with the knife package, and based on which the blade projection is determined. The slicing knife has at least one recess that originates in a rearward longitudinal edge, whereby the reference surface is arranged on the projection inside the recess, the projection extending vertically to the bearing surface.