Patent ID: 8052361

Claim:
A drill bit having a shank, a body and a cutting tip and adapted for rotation about its axis to drill holes in a carboresin material, comprising: a plurality of helical flutes in said body separated by helical lands defining the cutting diameter of said bit, each land having a lip presenting a helical cutting edge, at least two of said lands terminating in a cutting tip having an obtuse point angle, notches formed between said at least two lands by axially and radially extending flat faces and inclined ramps which extend rearwardly from said tip at an obtuse angle to said flat faces, respectively, said notches serving to convey material cut by said cutting tip to said helical flutes, said at least two lands having transition portions curving radially inward from said drill diameter to said cutting tip at a predetermined radius between 5 and 20 inches; and wherein the junction of said lands with their respective transition portions are chamfered at a radius greater than said predetermined radius.