DRILL BIT

A drill bit 100 has an end portion 106 for axial drilling, a cutting section 110 for lateral cutting between the end portion and a shank portion 120, the cutting section being cut at a helix angle (preferably 15{ Ò2{) to form of a pair of helical flutes 130 with sharpened edges 132 around a central core 104, the central core having a diameter directly proportional to the diameter of the bit and the axial length of the cutting edges being directly proportional to the length of the flutes, calculated according to the formula: cutting edge length = bit diameter Í f Í Cc / Tan (helix angle) where Cc is a constant with a value between 0.85 and 0.9. The length of the cutting edges may be directly proportional to the length of the flutes. The flutes may have a radial rake angle of 10{ (+3{/-0{), the cutting edges may have a cutting angle of 45{Ò2{, the drill bit diameter may be approximately 3.5mm, 3.175mm or 6.35mm and the length of the drill bit body may be 70-80 mm.