Abstract: A drill includes a flute and a shank, a feed screw extends axially from an end of the flute. A plurality of first cutting edges extend radially from the flute and are arranged in spiral form. A plurality of second cutting edges are formed on respective tops of the first cutting edges and these second cutting edges are dull when compared with the first cutting edges. Each second cutting edge has a thick support portion connected at a root portion thereof.

Abstract: A MULTIPLE SPUR MULTIPLE SPIRAL GROOVE TWIST DRILL includes a flute, whose shank is clamped and secured to a tooling holder of a drilling machine and contains multiple spiral flute grooves; each flute groove is disposed on its peripheral a flute land, a cutting section is formed on a front tip of the flute land; a spur formed at where the cutting section and the flute land crossing each other; and a lead screw point with tapered thread being disposed at a center on the front of the flute to increase strength of the cutting section; and the flute groove in conjunction with the flute to fortify the overall structural strength to provide longer service life and cost benefits of the drill.