Patent ID: 7195086

Claim:
An earth-boring bit, comprising: a bit body, the bit body having a central axis of rotation; at least one cutter rotatably mounted on said bit body, the cutter having a central axis; a plurality of cutting elements, each cutting element having a centerline, the cutting elements arranged on the cutter in generally circumferential rows; wherein at least one circumferential row contains varied pitch between adjacent cutting elements, having a maximum pitch and a minimal pitch; for said row, at least 20% of pitches have a mathematically determined pair, and a difference in absolute value between said pitch and its pair is greater than 10% of a difference in absolute value between the maximum and the minimum pitch for that circumferential row, said pair pitch is determined by measuring an arc from the midpoint of said initial pitch along said circumferential row in the direction opposite to the direction of cutter rotation during drilling, said arc equals to the length of said circumferential row (2*π*r) multiplied by the decimal part of Kv L=2*π* r *KvD; a plurality of generatrices, each generatrix defined as the geometric locus on the surface of the cutter formed when a plane containing the central axis of the cutter intercrosses the centerline of at least one selected cutting element and the geometric surface of the cutter; cutting elements in other circumferential rows being aligned along said generatrix with deviation from said generatrix of less than have the maximum pitch of the circumferential row occupied by the cutting element.