Downhole tools are provided with a topographical pattern, and anti-balling material is provided over the topographical pattern. The topographical pattern may be defined by at least one of a plurality of recesses extending into a surface of a body of the tool and a plurality of protrusions protruding from the surface. Downhole tools include an insert disposed within a recess in a body, and the insert comprises an anti-balling material having a composition selected to reduce accumulation of formation cuttings on the tools when the tools are used to form or service a wellbore. Downhole tools include anti-balling material disposed over a porous mass provided over the surfaces of the tools. Methods of forming downhole tools include providing anti-balling material over features on and/or in a surface of a body of a tool. Methods of repairing downhole tools include removing an insert therefrom and disposing a replacement insert therein.

Downhole tools are provided with a topographical pattern, and anti-balling material is provided over the topographical pattern. The topographical pattern may be defined by at least one of a plurality of recesses extending into a surface of a body of the tool and a plurality of protrusions protruding from the surface. Downhole tools include an insert disposed within a recess in a body, and the insert comprises an anti-balling material having a composition selected to reduce accumulation of formation cuttings on the tools when the tools are used to form or service a wellbore. Downhole tools include anti-balling material disposed over a porous mass provided over the surfaces of the tools. Methods of forming downhole tools include providing anti-balling material over features on and/or in a surface of a body of a tool. Methods of repairing downhole tools include removing an insert therefrom and disposing a replacement insert therein.

A method of joining a plurality of parts to form a unitary body. At least two sintered parts are provided. At least one of the sintered parts has at least one internal cavity. Each of the parts is formed of a hard metal composition of material. The at least two sintered parts are assembled into the shape of a unitary body. Each of the at least two sintered parts has a joining surface and when each joining surface is brought into contact the surfaces form a bonding interface therebetween. The assembled parts are subjected to a vacuum or gas atmosphere, without the application of external pressure, and to a temperature sufficient to fuse the at least two sintered parts together at the bonding interface to form the unitary body.

A method of joining a plurality of parts to form a unitary body. At least two sintered parts are provided. At least one of the sintered parts has at least one internal cavity. Each of the parts is formed of a hard metal composition of material. The at least two sintered parts are assembled into the shape of a unitary body. Each of the at least two sintered parts has a joining surface and when each joining surface is brought into contact the surfaces form a bonding interface therebetween. The assembled parts are subjected to a vacuum or gas atmosphere, without the application of external pressure, and to a temperature sufficient to fuse the at least two sintered parts together at the bonding interface to form the unitary body.

Provided are a drill blank, a method for manufacturing a blank, a drill, and a method for manufacturing a drill which allow a step of brazing to be easy and allow the brazing to be precise. A drill includes a drill blank brazed thereto in an elongated columnar-shape and made of cemented carbide. In the drill blank, both d.sub.A and d.sub.B are equal to or smaller than 2 mm, d.sub.Ad.sub.B>d.sub.C, a ratio of the length to d.sub.A is equal to or larger than 3, and d.sub.B/d.sub.A=0.96 to 1 and d.sub.C/d.sub.A=0.9 to 0.995 in a longitudinal direction, where d.sub.A indicates the diameter of one end of both ends, d.sub.B indicates the diameter of the other end thereof, and d.sub.C indicates the minimum diameter of a central portion. Brazing of the drill blank is easy and precision in brazing is enhanced.

Provided are a drill blank, a method for manufacturing a blank, a drill, and a method for manufacturing a drill which allow a step of brazing to be easy and allow the brazing to be precise. A drill includes a drill blank brazed thereto in an elongated columnar-shape and made of cemented carbide. In the drill blank, both d.sub.A and d.sub.B are equal to or smaller than 2 mm, d.sub.Ad.sub.B>d.sub.C, a ratio of the length to d.sub.A is equal to or larger than 3, and d.sub.B/d.sub.A=0.96 to 1 and d.sub.C/d.sub.A=0.9 to 0.995 in a longitudinal direction, where d.sub.A indicates the diameter of one end of both ends, d.sub.B indicates the diameter of the other end thereof, and d.sub.C indicates the minimum diameter of a central portion. Brazing of the drill blank is easy and precision in brazing is enhanced.

Downhole tools with a topographical pattern, and anti-balling material over the topographical pattern. The topographical pattern may be defined by at least one of a plurality of recesses extending into a surface of a body of the tool and a plurality of protrusions protruding from the surface. Downhole tools include an insert disposed within a recess in a body, and the insert comprises an anti-balling material having a composition selected to reduce accumulation of formation cuttings on the tools when the tools are used to form or service a wellbore. Downhole tools include anti-balling material disposed over a porous mass provided over the surfaces of the tools. Methods of forming downhole tools include providing anti-balling material over features on and/or in a surface of a body of a tool. Methods of repairing downhole tools include removing an insert therefrom and disposing a replacement insert therein.

Downhole tools with a topographical pattern, and anti-balling material over the topographical pattern. The topographical pattern may be defined by at least one of a plurality of recesses extending into a surface of a body of the tool and a plurality of protrusions protruding from the surface. Downhole tools include an insert disposed within a recess in a body, and the insert comprises an anti-balling material having a composition selected to reduce accumulation of formation cuttings on the tools when the tools are used to form or service a wellbore. Downhole tools include anti-balling material disposed over a porous mass provided over the surfaces of the tools. Methods of forming downhole tools include providing anti-balling material over features on and/or in a surface of a body of a tool. Methods of repairing downhole tools include removing an insert therefrom and disposing a replacement insert therein.

A rotary cutting tool comprises an elongate body disposed about a longitudinal axis, the elongate body including a helical flute and a polycrystalline-diamond cutting tip. The cutting tip comprises an inner portion having an inner point angle and an outer portion having an outer point angle different from the inner point angle.

A method of manufacturing a drill bit includes providing a piece of bar stock having a first end, a second end opposite the first end, and an axis of rotation extending centrally through the bar stock between the first and second ends, cutting the first end of the bar stock to form a first tip angle at an oblique angle measured through the axis of rotation, cutting the first end of the bar stock at a second tip angle measured through the axis of rotation to form first tip surfaces and second tip surfaces. The first tip surfaces have the first tip angle and the second tip surfaces have the second tip angle. The second tip angle is smaller than the first tip angle. Finally forming a flute in the bar stock between the first and second ends and forming a shank at the second end of the bar stock.