Methods for attaching cutting elements to an earth-boring bit rely on keying the cutting elements inside cavities formed in the earth-boring bit. The attachment methods may involve specific shapes of the cutting elements and the cavities in which the cutting elements are received, and/or mechanical retainers. Preferably, the blade of the earth-boring bit is thicker around the opening in the edge of the blade than when the cavity is shaped for receiving a cutting element that has a circular cross-section.

A sensor element for a cutting tool (100) has a hard portion (110) having a sensing surface (112), first and second electrodes (120, 130), first and second sets of thermocouple wires (122, 132) and an electrically insulating portion. The first and second electrodes (120, 130) are arranged to allow electric current to flow when the sensing surface (112) contacts external material in response to the cutting tool engaging the external material. A first thermocouple junction (124) is operable to indicate a temperature of the first electrode and a second thermocouple junction (134) is operable to measure temperature of the second electrode.

A sensor element for a cutting tool (100) has a hard portion (110) having a sensing surface (112), first and second electrodes (120, 130), first and second sets of thermocouple wires (122, 132) and an electrically insulating portion. The first and second electrodes (120, 130) are arranged to allow electric current to flow when the sensing surface (112) contacts external material in response to the cutting tool engaging the external material. A first thermocouple junction (124) is operable to indicate a temperature of the first electrode and a second thermocouple junction (134) is operable to measure temperature of the second electrode.

A drill bit having a rotatable ball bit includes a first bit head and a second bit head, a first set of cutters on the first bit head, and a second set of cutters on the second bit head. The rotatable ball bit is configured to rotate between a first position and a second position, wherein the first bit head is distal to the second bit head in the first position, and wherein the second bit head is distal to the first bit head in the second position. A method of operating a rotatable ball bit includes orienting the rotatable ball bit in a first position, wherein a first bit head is oriented distally, rotating the rotatable ball bit about a longitudinal axis, orienting the rotatable ball bit in a second position, wherein a second bit head is oriented distally, and rotating the rotatable ball bit about the longitudinal axis.

A drill bit having a rotatable ball bit includes a first bit head and a second bit head, a first set of cutters on the first bit head, and a second set of cutters on the second bit head. The rotatable ball bit is configured to rotate between a first position and a second position, wherein the first bit head is distal to the second bit head in the first position, and wherein the second bit head is distal to the first bit head in the second position. A method of operating a rotatable ball bit includes orienting the rotatable ball bit in a first position, wherein a first bit head is oriented distally, rotating the rotatable ball bit about a longitudinal axis, orienting the rotatable ball bit in a second position, wherein a second bit head is oriented distally, and rotating the rotatable ball bit about the longitudinal axis.

A rolling cone drill bit for drilling a borehole in earthen formations includes a bit body having a bit axis. In addition, the rolling cone drill bit includes a rolling cone cutter mounted on the bit body and having a cone axis of rotation. The cone cutter includes a cone body, a plurality of teeth arranged in a first inner row, and a plurality of inserts. Each insert is disposed within one tooth in the first inner row.

A rolling cone drill bit for drilling a borehole in earthen formations includes a bit body having a bit axis. In addition, the rolling cone drill bit includes a rolling cone cutter mounted on the bit body and having a cone axis of rotation. The cone cutter includes a cone body, a plurality of teeth arranged in a first inner row, and a plurality of inserts. Each insert is disposed within one tooth in the first inner row.

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.

Rotary drill bits may include on or more cutting element assemblies which include a cutter and a mounting system. In one embodiment, the mounting system includes a housing, a first bearing component disposed within the housing, and a second bearing component associated with the cutting element. In certain embodiments, the bearing components may comprise a table of superhard material bonded with a substrate. In one or more embodiments, the bearing components may include bearing surfaces that are arcuate. For example, the bearing surfaces may be substantially spherical (a portion of a sphere). The bearing components may be arranged to act as a radial bearing as well as a thrust bearing for the cutting element, enabling the cutting element to rotate about a longitudinal axis of the cutter, relative to the housing, while also enabling the longitudinal axis of the cutter to be displaced (change angles) relative to the housing.