Step drill bit

A step drill bit comprising:

• a shank extending along a bit axis;
• a body having a proximal end adjacent the shank and a distal end opposite the proximal end, the body defining a plurality of axially stacked, progressively sized steps including a first step at the distal end, a terminal step at the proximal end, and a plurality of intermediate steps having incrementally increasing diameters disposed between the first and terminal steps;
• a flute in the body extending from the distal end to the proximal end;
• and
• a plurality of cutting edges formed in the body, each cutting edge disposed along one of the plurality of steps, each cutting edge defining a helix angle and a radial rake angle;
• wherein the radial rake angle of the cutting edge at the terminal step is greater than the radial rake angle of the cutting edge at the first step, and
• wherein the radial rake angles of the cutting edges incrementally increase from a first step of the plurality of intermediate steps to a second step of the plurality of intermediate steps, and from the second step of the plurality of intermediate steps to a third step of the plurality of intermediate steps.

A step drill bit comprising:

• a shank extending along a bit axis;
• a body having a proximal end adjacent the shank and a distal end opposite the proximal end, the body defining a plurality of axially stacked, progressively sized steps including a first step at the distal end, a terminal step at the proximal end, and a plurality of intermediate steps having incrementally increasing diameters disposed between the first and terminal steps;
• a flute in the body extending from the distal end to the proximal end;
• and
• a plurality of cutting edges formed in the body, each cutting edge disposed along one of the plurality of steps, each cutting edge defining a helix angle and a radial rake angle;
• wherein the helix angle of the cutting edge at the terminal step is greater than the helix angle of the cutting edge at the first step;
• wherein the helix angles of the cutting edges incrementally increase from a first step of the plurality of intermediate steps to a second step of the plurality of intermediate steps, and from the second step of the plurality of intermediate steps to a third step of the plurality of intermediate steps.