Patent ID: 7798186

Claim:
A wood cutting apparatus, comprising: a first hub axially disposed for rotation about an axis, said first hub having a first pocket for receiving a first knife; and a first screw having a frustoconical portion for wedging said first knife in said first pocket, wherein said first knife has at least two curvilinear cutting edges disposed with 90 degree rotational symmetry, said knife having a front side and a spaced apart, planar back side and a beveled face connecting said front and back sides at respective outer peripheral contours thereof, wherein the outer peripheral contour of said front side includes said curvilinear cutting edges, wherein, in a cross-section of the knife taken in a first plane perpendicular to the plane of said front side and to the peripheral outer contour thereof, said beveled face defines, over the lengths of said curvilinear cutting edges, an attack relief angle with respect to said first plane, wherein said attack relief angle is in the range 25-40 degrees.