Drill bits with dropping tendencies

摘要

A drill bit 710 has first and second blades 739,741 with first 750 and second cutters arranged on respective blades. The first arrangement of cutters extend to a primary cutting profile. The second arrangement of cutters is unique with respect to the first arrangement and includes a first plurality of cutters 756 which extend to the primary cutting profile and a second plurality of cutters 754 which are recessed from the primary cutting profile. A third arrangement of cutters 752 is disposed on the first blade 739 and are positioned behind the first arrangement of cutter 750 at radial positions corresponding to radial locations of said second plurality of cutters such that in rotated profile the third arrangement 752 of cutters overlaps with said second plurality of cutters.