Patent ID: 9687915
Date: 2017-06-27
CPC Classifications: B23B,Y10T

Claim:
1. A step drill bit comprising: a cutting head defining a longitudinal axis; a first flute and a second flute dividing the cutting head into a first land and a second land, each of the first land and the second land comprising a plurality of steps having different effective diameters; each of the plurality of steps of the first land comprising; each of the plurality of steps in the second land comprising: a negative radial relief provided between at least one of the first cutting edge and the first trailing edge of the first land or the second cutting edge and the second trailing edge of the second land in at least two of the plurality of steps of the first land and the second land, wherein the negative radial relief increases a radius of the first land between the at least one of the first cutting edge and the first trailing edge and towards the first trailing edge or of the second land between the second cutting edge and the second trailing edge and towards the second trailing edge in at least two of the plurality of steps, wherein the first cutting edge and the second cutting edge are arranged such that the bit is asymmetric in a plane perpendicular to the longitudinal axis relative to a plane containing the longitudinal axis.