Patent ID: 8911280

Claim:
An apparatus for shaping an exterior surface of a metal alloy casing of a portable electronic device, the apparatus comprising: a cutting tool having at least three cutting surfaces for abrading a plurality of regions of the metal alloy casing; and a computer numerically controlled (CNC) positioning assembly configured to rotate the cutting tool at a constant rotational velocity and to contact the rotating cutting tool along a pre-determined continuous path at a constant translational velocity to abrade the metal alloy casing; wherein the at least three cutting surfaces of the cutting tool include a first flat cutting surface nearest to a neck of the cutting tool to shape a flat edge region on the top of the metal alloy casing; a curved convex shaped cutting surface adjacent to the first flat cutting surface to shape a curved edge region of the metal alloy casing; and a second flat cutting surface on the bottom of the cutting tool to shape a flat bottom region of the metal alloy casing; and wherein the pre-determined continuous path includes a continuous spiral path used to shape the flat edge region and to shape the curved edge region and a continuous zigzag path to shape the flat bottom region of the metal alloy casing; and wherein a spacing between adjacent circuits of the continuous spiral path varies based on a curvature of a cross section of the surface of the metal alloy casing.