Patent ID: 9731358
Date: 2017-08-15
CPC Classifications: B23B,Y10T

Claim:
1. A drill bit comprising: a shank extending along a bit axis; a transition portion coupled to the shank; a body portion having a distal end and defining a plurality of axially stacked, progressively sized steps including a first step at the distal end and a terminal step coupled to the transition portion, the first step defining two tip flutes each disposed at a tip flute angle from the bit axis, the body portion further defining two body flutes each extending from the first step to the transition portion and disposed at a body flute angle different from the tip flute angle; and a bit tip disposed at the distal end of the body portion and having a chisel edge intersecting the bit axis, a first chisel surface being on one side of the chisel edge, and a second chisel surface being on an opposite side of the chisel edge, the first chisel surface defining a first relief angle, and the second chisel surface defining a second relief angle that is different from the first relief angle; wherein each tip flute extends to the first chisel surface or the second chisel surface to define at least part of an edge of the first chisel surface or the second chisel surface; wherein the body flute angle of each body flute is formed as a compound angle defined by a first body flute angle and a second body flute angle, where the first body flute angle is measured between a centerline of each body flute and the bit axis in a first plane, and the second body flute angle is measured between the centerline of each body flute and the bit axis in a second plane that is orthogonal to the first plane; wherein the first body flute angle is between approximately 4.5 degrees and approximately 5.5 degrees, and wherein the second body flute angle is between approximately 1 degree and approximately 3 degrees.