TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractBased on computer drilling simulation results, a new, unique roller cone bit has been developed 1 . All the teeth on this new bit are oriented optimally such that the leading face of the elongated crest of a tooth is perpendicular to its trajectory during interaction with a formation. This paper describes the computer model, the calculation procedure for determining the trajectories of the teeth, and the method for designing the new bit. Laboratory and field tests have shown that the new bits drill up to 25% faster and longer than the same type of bits with conventional tooth design.