A cutter head assembly for a planing apparatus comprises a rotatable cutter head body, at least a first slot and a gib assembly positionable in the first slot to retain a planing knife blade. The cutter head body has a first end, an opposite second end and an outer periphery extending between the first and second ends in a longitudinal direction. The first slot is formed in the outer periphery and extends generally longitudinally. A section of the first slot has at least one profiled side and an opposite knife blade side. The gib assembly is positionable to retain a knife blade in the first slot adjacent the knife blade side. The gib assembly comprises an elongate gib having a section with a shaped leading side and an opposite trailing side. A gib screw is rotatable to move the gib toward the knife blade and clamp it.