Abstract: Disclosed is a drill bit for use downhole in oil and gas wells. It is particularly adoptable for use in removing obstructions such as well packers which may become jammed within the casings of oil and gas wells. Cutters are arranged on the cutting face of the drill bit in arc-like patterns of decreasing radius. The shear angle of each cutter combined with the arc-like pattern in which the cutters are arranged serve to direct the cuttings and drilling debris inward toward the central bore. Fluid can be pumped down through the well casing and circulated about the drill bit through longitudinal channels provided in the main body of the drill bit. In such manner, the fluid circulates downward within the casing and across the cutting face of the drill bit carrying the cuttings and drilling debris up through the central bore thus preventing the cuttings in drilling debris from building up within the casing or causing the drill bit to jam within the casing.

Abstract: Disclosed is a method directed particularly to improving a modified threaded buttress collar. The method is also of value with any internally threaded member having a seal ring groove therein. The method specifically deals with the removal of the feather edge thread created when a seal ring groove is placed within an internally threaded member. Such groove usually provides residence for a seal ring. When the groove is placed in the internally threaded member there is created a feather edge thread immediately adjacent the groove. This feather edge thread is easily deformable and can create severe galling problems within the coupling.The feather edge is removed, preferably, in stepped fashion utilizing a machining tool such as a grooving tool within a computer numerically controlled lathe. The grooving tool is set such that as the coupling turns in the lathe, the movement of the grooving tool matches the pitch and helix of the threads and the speed of the lathe.