Borehole angle control by gage corner removal from mechanical devices associated with drill bit and drill string

Apparatus for use with a rotary drill bit and a drill string to selectively control the advancement angle of a borehole cut in material, the drill bit comprising cutting elements arranged for cutting an axially extending cylindrical sidewall of the borehole, a drill face of the borehole extending transversely with respect to the sidewall and a gage corner of the borehole extending circumferentially from the drill face radially outward at an inclination to the sidewall, and an improved connector means for connecting said drill bit to the end of said drill string, said connector means comprising:

• an upper body segment adapted to be fixed to the end of said drill string,
• a lower body segment adapted to be fixed to the drill bit,
• hinge connecting means for hingeably connecting the lower body segment to the upper body segment at a hinged connection point radially offset from a rotational axis reference of said body segments, said hinge connecting means further operatively connecting the upper and lower body segments to resist rotation relative to one another;
• extendable means operatively positioned with respect to the hinge connection point for selectively pivoting of the lower segment with respect to the upper segment when activated;
• and
• activation means adapted for selectively activating said extendable means during only a predetermined partial interval of one drill bit rotation.

A rotary drill bit for selectively controlling the advancement angle of a borehole cut by rotating said drill bit against material, comprising:

• a bit support structure,
• a single cutting wheel member having a wheel portion and an axle portion, the axle portion extending from the wheel portion, the wheel portion on the side opposite the axle portion including cutting elements arranged for cutting an axially extending cylindrical sidewall of the borehole and a drill face of the borehole extending essentially transversely with respect to the sidewall and a gage corner of the borehole extending circumferentially from the drill face radially outward at an inclination to the sidewall;
• means for rotatably connecting said cutting wheel member to said bit structure, said rotatably connecting means further comprising an opening formed in said support structure and means for attaching the axle portion in said opening with the axle portion extending at an intersecting angle with respect to an axial reference and in spaced parallel relation with respect to a radial reference through the rotational center of said drill bit;
• extendable means operatively connected between the axle portion of said cutting wheel and the bit support structure for pivoting the axle portion of said cutting wheel to a slightly lesser intersecting angle with respect to the axial reference through said drill bit when activated;
• and
• activation means adapted for selectively activating said extendable means only during a predetermined partial interval of one drill bit rotation.