Patent ID: 7524237

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 movable among multiple direction to confront the hard and brittle workpiece and supported for rotation to establish a second axis oriented to lie in a non-parallel relation to the first axis, a diamond tool blade formed to include a circular cutting edge and coupled to the spin-turner mechanism and wherein the diamond tool blade includes first and second chemically faceted surfaces intersecting to define the circular cutting edge, the diamond tool blade being made of two-part multi-modal polycrystalline diamonds varying in size of about 2 μm to about 50 μm, hot isostatically pressed in a cobalt binder of about 10% cobalt whereby the chemical faceted surfaces are faceted by machining using a scaife having a machining compound deposited on the scaife surface and wherein the machining occurs in the presence of a machining gas, and wherein the diamond tool blade is annular in shape and includes space-apart planar top and bottom surfaces and an annular side wall extending therebetween, the first chemically faceted 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 wall adjacent to an outer rim of the bottom surface, and the second chemically faceted surface defining a nose facet extending between the negative rake facet and the base portion.