Rotary drill bit with cutting insert having edge preparation

A rotary drill bit for engaging an earth strata material, the rotary drill bit comprising:

• an elongate drill bit body having an axial forward end and an axial rearward end;
• and
• a cutting insert attached to the axial forward end of the elongate drill bit body, the cutting insert having an elongate insert body rotatable about a central axis, the elongate insert body having a pair of symmetrical halves symmetrical about the central axis, each symmetrical half comprising:
• a leading face;
• a top surface having a primary relief surface and a secondary relief surface, wherein the primary relief surface is perpendicular to the leading face;
• a T-land surface extending between the leading face and the primary relief surface of the top surface;
• and
• a cutting edge formed at the intersection of the T-land surface and the primary relief surface of the top surface;
• wherein the secondary relief surface extends continuously from the primary relief surface to a rearward face of the cutting insert.