US Patent 7201544 Deep hole boring drill

A drill for producing a deep hole that does not produce a bend of the hole during cutting. A drill body is spirally provided with a pair of cutting edges. The cutting edges are spaced at about 180 degrees apart around a core of the drill and the edge line of a tip section of the cutting edges is depressed toward the core of the drill. When the outside dimension of the drill is 7.4 mm, an angle between the edge line and a line perpendicular to the core is 5 degrees and the core thickness (t) is 2.96 mm. Further, the drill is provided with a guide section for preventing bending during a cutting operation. The guide section is provided on a heel side on the same circumference as that on which the outer end section of the cutting edges passes.