Abstract: A chamfering apparatus for use in machining corner breaks of work pieces and including a base member establishing a horizontal support surface, a guide block mounted on the base member and forming a guide surface substantially normal to the horizontal support surface such that a trim slot is formed about he intersection of the plane of the horizontal support surface and the plane of the frontal vertical guide surface; a circular cutting member having an axis of rotation parallel with the axis of the trim slot positioned about the base member with the outer peripheral edge of the cutting member extending within the trim slot such that the edge of a work piece may be chamfered as it is moved along the trim slot while in abutting relationship to the horizontal support surface and frontal vertical guide surface.