Nutating drill bit

Abstract From the Canadian patent

A nutating earth drilling bit which is adapted for use in drilling systems in which the drilling fluid and cuttings are transported from bit to surface through the interior of the drill string. The nutating bit is provided with a toroidal cutting member and a longitudinally extending annular shank both of, which have longitudinally extending central passageways aligned with one another and in flow communication with the central return conduit of the drill string. The cutting member of one embodiment has a segmented cutting web at its lower end which divides the central passageway into three separate fluid return channels. Another embodiment drills an annular hole face around an uncut earth …