US Patent 7341118 Rotating dry drilling bit

A rotating dry drilling bit for low thrust drilling of an annular bore hole into a body of rock and obtaining an extremely small diameter core sample comprises a bit crown moulded to the end of an annular steel body. The bit crown comprises a plurality of radially extending channels and a plurality of evenly spaced radially extending cutting blades surrounding an annulus. The bit crown is a hard metal matrix formed onto the bottom end of the annular steel body using a powdered metallurgy process. Embedded within each cutting blade are natural and synthetic diamonds. A reverse auger mechanism within the annulus removes cuttings from the annulus and the surface of the bit crown.