Patent ID: 7390242

Claim:
An apparatus for turning a hard and brittle material, the apparatus comprising a base including a workpiece spindle adapted to receive a hard and brittle workpiece coupled for rotation about a first axis, a spin-turner mechanism positioned to confront the hard and brittle workpiece and supported for rotation about a second axis oriented to lie in non-parallel relation to the first axis, and a single-crystal diamond tool blade for removing material from the hard and brittle workpiece, the single-crystal diamond tool blade being mounted on the spin-turner mechanism to rotate therewith about the second axis to machine and polish the hard and brittle workpiece during rotation of the hard and brittle workpiece about the first axis wherein the diamond tool blade is annular in shape and includes spaced-apart planar top and bottom surfaces and an annular side wall extending therebetween, a first surface defining a negative rake facet formed on an upper portion of the annular side wall adjacent to an outer rim of the planar top surface, a base portion formed on the side wail adjacent to an outer rim of the bottom surface, and a second surface defining a nose facet extending between the negative rake facet and the base portion.