Drilling of conical and cylindrical holes in wood, plastics or metal - using bit with conically converging cutting flanks sepd. by continuous slot

摘要

Method is carried out with a hand-held power drill with a bit having conically converging cutting flanks with sharpened edges which are sepd. from each other by a continuous slot. Pref. at the lower most conical portion of the bit is cut, screwed in or rivetted a tip corresponding to the material to be drilled. Automatic fine control of collection of shavings may be provided by resilient counteraction of the conical wall portions which are sharpened at the edges. Sudden jamming of the bit in the workpiece is prevented, and conical holes can be made easily in a single operation, with little application of force.