A drill bit for drilling a bore, the drill bit comprising: an outer housing; a primary cutting structure defining a cutting plane of a first diameter; a flow path arranged to let drilling fluid flow through the drill bit; and a deployable blade assembly at least partially located within the outer housing, the deployable blade assembly comprising a cutting structure and being arranged to be axially movable from a first position, in which the deployable cutting structure is recessed with respect to the primary cutting structure, towards the cutting plane, to a second position; wherein when the deployable blade assembly is in the second position, the deployable cutting structure defines a cutting diameter which is less than or equal to the first diameter.

A hybrid drill bit includes both fixed cutting elements and an adjustable cutting structure thereon. An adjustment mechanism is provided to allow an axial position of cutting elements at a leading end of the adjustable cutting structure to be adjusted with respect to an axial position of the fixed cutting elements. The adjustable cutting structure may include counter rotational cutting members mounted obliquely with respect to a bit body rotational axis, and the adjustment mechanism may dynamically support the adjustable cutting structure such that the axial position of the cutting elements may be adjusted as the drill bit is in operation within a wellbore. The axial position may be adjusted by altering a weight applied to the drill bit within the wellbore.

A hybrid drill bit includes both fixed cutting elements and an adjustable cutting structure thereon. An adjustment mechanism is provided to allow an axial position of cutting elements at a leading end of the adjustable cutting structure to be adjusted with respect to an axial position of the fixed cutting elements. The adjustable cutting structure may include counter rotational cutting members mounted obliquely with respect to a bit body rotational axis, and the adjustment mechanism may dynamically support the adjustable cutting structure such that the axial position of the cutting elements may be adjusted as the drill bit is in operation within a wellbore. The axial position may be adjusted by altering a weight applied to the drill bit within the wellbore.

A retractable auger boring cutter head. The cutter head has fixed cutters and at least one pivoting cutter. The pivoting cutter is biased to a position that extends beyond a diameter of a casing being installed. When pulled back through the casing, a surface of the pivoting cutter contacts the casing, reducing the effective diameter of the cutter head and allowing it to be removed.

A retractable auger boring cutter head. The cutter head has fixed cutters and at least one pivoting cutter. The pivoting cutter is biased to a position that extends beyond a diameter of a casing being installed. When pulled back through the casing, a surface of the pivoting cutter contacts the casing, reducing the effective diameter of the cutter head and allowing it to be removed.

A method of manufacturing a roller cone for a drill bit includes: selectively carburizing a land of the roller cone between a plurality of spots on the land for protection against erosion; after carburization, forming sockets in the roller cone at the spots; and mounting cermet inserts in the sockets.

A method of manufacturing a roller cone for a drill bit includes: selectively carburizing a land of the roller cone between a plurality of spots on the land for protection against erosion; after carburization, forming sockets in the roller cone at the spots; and mounting cermet inserts in the sockets.

A drill bit device may include a cutter housing delimited by an outermost surface and various walls forming a socket. The drill bit device may include various main cutters disposed on an outermost surface of the cutter housing. The various main cutters may be configured to move in an outward direction upon receiving a predetermined pressure. The drill bit device may include various pre-charged cutters disposed immediately behind the various main cutters inside the cutter housing. The various pre-charged cutters may be configured to move in the outward direction upon receiving the predetermined pressure. The drill bit device may include a gate that connects the cutter housing to an internal groove that may be directly connected to a port switch that may allow release of the predetermined pressure through the internal groove and into the gate.

A method of improving the service life of a drill bit comprises creating a weldment between load bearing portions of the drill bit where the weldment has a preselected root gap greater than about 25 mils and a preselected root face greater than about 25 mils, and where the weldment has a material property greater than the materials being joined.

A method of improving the service life of a drill bit comprises creating a weldment between load bearing portions of the drill bit where the weldment has a preselected root gap greater than about 25 mils and a preselected root face greater than about 25 mils, and where the weldment has a material property greater than the materials being joined.