A drill bit for drilling a borehole in an earthen formation has a central axis and a cutting direction of rotation. The bit includes a bit body configured to rotate about the axis in the cutting direction of rotation. The bit body includes a bit face. The bit also includes a blade extending radially along the bit face. In addition, the bit includes a first cutter element mounted to a cutter-supporting surface of the blade and a second cutter element mounted to the cutter-supporting surface of the blade. The first cutter element has a central axis and includes a first forward-facing cutting face including a first cutting tip distal the cutter supporting surface and a first planar surface extending radially from the first cutting tip toward the central axis of the first cutter element. The first planar surface is oriented at a first effective backrake angle measured between the cutter supporting surface and a surface vector of the first planar surface. The second cutter element has a central axis and comprises a second forward-facing cutting face including a second cutting tip distal the cutter supporting surface and a second planar surface extending radially from the second cutting tip toward the central axis of the second cutter element. The second planar surface is oriented at a second effective backrake angle measured between the cutter supporting surface and a surface vector of the second planar surface. The second effective backrake angle is greater than the first effective backrake angle.

In a drill bit insert of the present invention, an insert body of the drill bit insert includes: a rear end portion forming a columnar shape or a disk-like shape; an intermediate portion having an outer diameter smaller than that of the rear end portion; and an end portion having an outer diameter from the center line of the insert gradually decreasing toward the tip side, the hard surface layer is coated on the insert body from a surface of the end portion of the insert body to an outer periphery of the intermediate portion, and an outer diameter of the hard surface layer on the intermediate portion is equal to that of the rear end portion.

Systems and methods are disclosed for a rotating superhard cutting element. The rotating cutting element includes a substrate comprising a rotating portion and a stable portion. The stable portion has a cavity and is configured to be fixed to a blade of a drill bit. The rotating cutting element further includes a retainer that rotatably secures the rotating portion of the substrate in the cavity of the stable portion of the substrate, and a cutting layer on the rotating portion of the substrate. The cutting layer has a plurality of cutting surfaces. One of the plurality of cutting surfaces has a property different from another one of the plurality of cutting surfaces. The cutting layer is configured to rotate with respect to the stable portion of the substrate and use one of the plurality of cutting surfaces based on a characteristic of a formation to be cut.

Systems and methods are disclosed for a rotating superhard cutting element. The rotating cutting element includes a substrate comprising a rotating portion and a stable portion. The stable portion has a cavity and is configured to be fixed to a blade of a drill bit. The rotating cutting element further includes a retainer that rotatably secures the rotating portion of the substrate in the cavity of the stable portion of the substrate, and a cutting layer on the rotating portion of the substrate. The cutting layer has a plurality of cutting surfaces. One of the plurality of cutting surfaces has a property different from another one of the plurality of cutting surfaces. The cutting layer is configured to rotate with respect to the stable portion of the substrate and use one of the plurality of cutting surfaces based on a characteristic of a formation to be cut.

A method for forming localized binder in a drilling tool is disclosed. A method includes placing a reinforcement material in a matrix bit body mold, placing a localized binder material within the reinforcement material at a selected location in the matrix bit body mold, wherein the localized binder material confers a selected physical property at the selected location, placing a universal binder material in the matrix bit body mold on top of the reinforcement material, heating the matrix bit body mold, the reinforcement material, the localized binder material, and the universal binder material to a temperature above the melting point of the universal binder material, infiltrating the reinforcement material and the localized binder material with the universal binder material, and cooling the matrix bit body mold, the reinforcement material, the localized binder material, and the universal binder material to form a matrix drill bit body.

A method for forming localized binder in a drilling tool is disclosed. A method includes placing a reinforcement material in a matrix bit body mold, placing a localized binder material within the reinforcement material at a selected location in the matrix bit body mold, wherein the localized binder material confers a selected physical property at the selected location, placing a universal binder material in the matrix bit body mold on top of the reinforcement material, heating the matrix bit body mold, the reinforcement material, the localized binder material, and the universal binder material to a temperature above the melting point of the universal binder material, infiltrating the reinforcement material and the localized binder material with the universal binder material, and cooling the matrix bit body mold, the reinforcement material, the localized binder material, and the universal binder material to form a matrix drill bit body.

A method of forming a cutting element comprises disposing diamond particles in a container and disposing a metal powder on a side of the diamond particles. The diamond particles and the metal powder are sintered so as to form a polycrystalline diamond material and a low-carbon steel material comprising less than 0.02 weight percent carbon and comprising an intermetallic precipitate on a side of the polycrystalline diamond material. Related cutting elements and earth-boring tools are also disclosed.

A method of forming a cutting element comprises disposing diamond particles in a container and disposing a metal powder on a side of the diamond particles. The diamond particles and the metal powder are sintered so as to form a polycrystalline diamond material and a low-carbon steel material comprising less than 0.02 weight percent carbon and comprising an intermetallic precipitate on a side of the polycrystalline diamond material. Related cutting elements and earth-boring tools are also disclosed.

A reaming tool includes a reaming tool body configured to be coupled within a drill string or a string of drilling tools. A plurality of reaming blocks is attached to the reaming tool body at circumferentially spaced apart locations. At least one reaming block comprises at least a first row of gouging cutters and a second row of gouging cutters. The gouging cutters in the first row define a first profile. The gouging cutters in the second row define a second profile. The first row is rotationally ahead of the second row. The first profile at any longitudinal position along the at least one reaming block defines a larger reaming diameter than the second profile.

The force modulation system for a drill bit includes a cutter, a holder, a holder retention device, and a first force member made of a first woven material. The cutter fits in the holder, and the holder fits in the drill bit. The holder retention device exerts a holder retention force in a first direction. The first force member exerts a first force in a second direction. The second direction is angled offset to the first direction so as that a cutting profile of the force modulation system is variable. There can also be a second force member of a second woven material to exert a second force in the first direction for more variability of the cutting profile in the first direction. The second force member can be made integral with the first force member, including the first woven material and the second woven material being the same material.