Stress-reducing, torque transmission design for modular drills

A modular rotary cutting tool comprising:

• a shank comprising a pocket, the pocket comprising:
• a pocket floor;
• first and second pocket drive walls extending at non-parallel angles from the pocket floor, wherein the pocket floor, and the first and second pocket drive walls form the pocket;
• and
• a cutting insert removably installed in the pocket of the shank, the cutting insert comprising:
• first and second torque transmission insert drive surfaces;
• wherein the first pocket drive wall contacts the first torque transmission insert drive surface only somewhere in a middle 60% of a length of the first torque transmission insert drive surface, and the second pocket drive wall contacts the second torque transmission insert drive surface only somewhere in a middle 60% of the length of the second torque transmission insert drive surface.

A method of operating a modular rotary cutting tool comprising:

• rotating a shank of the modular rotary cutting tool, the shank comprising a pocket comprising a pocket floor and first and second pocket drive walls extending at non-parallel angles from the pocket floor, wherein the pocket floor, and the first and second pocket drive walls form the pocket;
• driving a first torque transmission insert drive surface of a cutting insert, removably installed in the pocket of the shank, with the first pocket drive wall, wherein the first pocket drive wall contacts the first torque transmission insert drive surface only somewhere in a middle 60% of a length of the first torque transmission insert drive surface;
• and
• driving a second torque transmission insert drive surface of a cutting insert, removably installed in the pocket of the shank, with the second pocket drive wall, wherein the second pocket drive wall contacts the second torque transmission insert drive surface only somewhere in a middle 60% of the length of the second torque transmission insert drive surface.