An earth-boring tool for removing subterranean formation material in a borehole comprises a tool body having a central axis defining an axial center thereof and a leg extending in an axial direction from the tool body. A bearing assembly is removably coupled to the leg and includes a bearing shaft and a base member. The base member encircles a portion of the bearing shaft and abuts against a surface of the leg. A roller cone is rotatably coupled to the bearing assembly and has a rotational axis about which the roller cone rotates on the bearing assembly when the roller cone removes subterranean formation material in the borehole. A method of assembling a rotatable cutting structure assembly including the bearing assembly includes coupling the bearing shaft to the leg by disposing a mechanical fastener through an aperture formed through the leg and into a cavity of the bearing shaft.

An earth-boring tool for removing subterranean formation material in a borehole comprises a tool body having a central axis defining an axial center thereof and a leg extending in an axial direction from the tool body. A bearing assembly is removably coupled to the leg and includes a bearing shaft and a base member. The base member encircles a portion of the bearing shaft and abuts against a surface of the leg. A roller cone is rotatably coupled to the bearing assembly and has a rotational axis about which the roller cone rotates on the bearing assembly when the roller cone removes subterranean formation material in the borehole. A method of assembling a rotatable cutting structure assembly including the bearing assembly includes coupling the bearing shaft to the leg by disposing a mechanical fastener through an aperture formed through the leg and into a cavity of the bearing shaft.

Bearings for earth-boring tools may include a first bearing member including a first bearing pad having a first contact surface and a second bearing member including a second bearing pad having a second contact surface in sliding contact with at least a portion of the first contact surface. At least one of the first bearing member and the second bearing member may include a polycrystalline table attached to a portion of a first substrate on which the polycrystalline table was formed. Another substrate may be attached to the portion of the first substrate, the portion of the first substrate interposed between the polycrystalline table and the other substrate. The portion of the first substrate may include a first volume percentage of the first matrix material and the other substrate may include a second, different volume percentage of the second matrix material

Bearings for earth-boring tools may include a first bearing member including a first bearing pad having a first contact surface and a second bearing member including a second bearing pad having a second contact surface in sliding contact with at least a portion of the first contact surface. At least one of the first bearing member and the second bearing member may include a polycrystalline table attached to a portion of a first substrate on which the polycrystalline table was formed. Another substrate may be attached to the portion of the first substrate, the portion of the first substrate interposed between the polycrystalline table and the other substrate. The portion of the first substrate may include a first volume percentage of the first matrix material and the other substrate may include a second, different volume percentage of the second matrix material

Hardfacing materials include a polymer matrix material and particles of hard material embedded within and dispersed throughout the polymer matrix material. Earth-boring tools include a tool body and a hardfacing material on at least a portion of a surface of the body, wherein the hardfacing material includes a polymer matrix material and particles of hard material embedded within and dispersed throughout the polymer matrix material. Methods of applying hardfacing material to an earth-boring tool comprise mixing hard particles with a polymer precursor material to form a paste, applying the paste to a surface of an earth-boring tool, and curing the polymer precursor material to form a hardfacing material on the surface of the earth-boring tool.

A hole opener includes a body with cone arms. The body includes pockets formed in the body in which each of the pockets includes a forwardly-positioned shoulder pocket section, a rearwardly-positioned tapered pocket section and a base opening axially extending through a wall of the corresponding pocket that receives a fastener therethrough. The cone arms each include a cone head attached to an arm. The arm includes a forwardly-positioned shoulder arm section, a rearwardly-positioned tapered arm section, and a rearwardly-facing opening axially extending through the rearwardly-positioned tapered arm section that receives the fastener. When each of the cone arms is inserted into a corresponding one of the pockets and the corresponding fastener(s) is/are tightened, the rearwardly-positioned tapered arm section is securely drawn into the rearwardly-positioned tapered pocket section of the pocket to create a pre-loaded fit therebetween and the forwardly-positioned shoulder arm section mates with the forwardly-positioned shoulder pocket section.

A sealed bearing rock bit has a plurality of legs with journals formed to extend inward and downward at the end of the legs. Each of the legs has a last machined surface located adjacent to the bases of the journals and into which a seal groove is formed which circumscribes the respective journal. Cutters are rotatably mounted to respective ones of the journals, with back faces of the cutters located adjacent to respective ones of the last machined surfaces. The back faces of the cutters have annular-shaped protrusions which extend from said back faces and protrude into the seal grooves beyond the last machined surfaces of said journals extending an annular-shaped seal surface which is engaged by a seal disposed in the seal groove, leaving more of the interface space between the journal and the cutter for larger roller bearings.

A sealed bearing rock bit has a plurality of legs with journals formed to extend inward and downward at the end of the legs. Each of the legs has a last machined surface located adjacent to the bases of the journals and into which a seal groove is formed which circumscribes the respective journal. Cutters are rotatably mounted to respective ones of the journals, with back faces of the cutters located adjacent to respective ones of the last machined surfaces. The back faces of the cutters have annular-shaped protrusions which extend from said back faces and protrude into the seal grooves beyond the last machined surfaces of said journals extending an annular-shaped seal surface which is engaged by a seal disposed in the seal groove, leaving more of the interface space between the journal and the cutter for larger roller bearings.

The present disclosure relates to roller cone drill bit journals with asymmetric ball races and extended friction races. The disclosure also relates to methods of forming such journals, and methods of finishing these journals to produce finished journals with symmetric ball races.

The present disclosure relates to roller cone drill bit journals with asymmetric ball races and extended friction races. The disclosure also relates to methods of forming such journals, and methods of finishing these journals to produce finished journals with symmetric ball races.