US Patent 7232311 Bur for preparing metal substrates

A method and bur is described for preparing a surface of a metal substrate. The bur includes a shank portion and a cutting head. The cutting head includes a base portion connected to the shank portion, a tip portion opposite the base portion and a plurality of similar blades defined by equal size bur grooves formed along a longitudinal axis of the cutting head. Each of the blades including a plurality of spaced dentates defined by a helical groove spiraling from the base portion to the tip portion in a counterclockwise direction about the circumference of the cutting head at an angle departing from a line perpendicular to the longitudinal axis at an angle from about 5 to about 18 degrees.