A drill bit for a drill includes a body clearance extending helically along the drill bit, a margin also extending helically along the drill bit, adjacent to and projecting radially beyond the body clearance, and a flank at which the body clearance and the margin terminate at a tip of the drill bit. The margin has a variable width along its helical extension.

Cutting elements may include points, tips, cutting portions and/or shafts of various geometries depending on requirements of the intended use. Tip geometries described may be used for cutting burrs, k-wires and/or drill bits in many types of applications. In particular, the tip geometries described may be used in medical applications. For example, tip geometries as described herein may be used for drilling bones, cartilage, and similar structures during surgery. Tip geometry may influence cutting ability. Use of the tip geometries described may allow the cutting element to be positioned at varying angles relative to the surface to be cut. In some instances, a tip geometry for a cutting element may be selected such that it reduces and/or inhibits movement of the cutting element during use and/or allows for a predetermined angle of entry into a surface to be cut. Using the designs described herein may reduce and/or inhibit damage, heat, and/or trauma to materials that are to be cut, for example, tissues such as bone and/or cartilage.

A cutting head rotatable about a central axis, comprising a tip portion and an intermediate portion. The tip portion has an axially forwardmost tip point contained in the central axis and three axially forward facing front surfaces forming three chisel edges extending axially rearwardly away from the tip point, each front surface having a radially extending cutting edge comprising a secondary cutting-edge portion extending radially outwardly from one of the chisel edges, and a primary cutting-edge portion extending radially outwardly therefrom. Each primary cutting-edge portion is contained in an imaginary annular ring surface having an annular ring width spanning at least radially inner and outer end points thereof. In a front-end view of the cutting head, each primary cutting-edge portion is concave, and radial planes intersect the imaginary annular surface to form imaginary rectilinear lines, each having a length equal to the annular ring width.

According to one implementation, a drill includes the first cutting edges, the second cutting edges and a deflection reducer. The first cutting edges drill a prepared hole to a workpiece. The first cutting edges are formed in a tip side of the drill. The first point angle and each first relief angle of the first cutting edges continuously or intermittently decrease from the tip side toward a rear end side of the drill. The second cutting edges finish the prepared hole. The second cutting edges are formed at positions away in the rear end side from the first cutting edges. The second cutting edges have the second relief angles at a maximum diameter position. The deflection reducer reduces deflection of the second cutting edges. The deflection reducer is formed between the first cutting edges and the second cutting edges. The deflection reducer is inserted into the prepared hole.

A cutting head rotatable about a first axis, comprising an intermediate portion and a tip portion. The intermediate portion has a plurality of leading edges defining a cutting diameter, and the tip portion has an axially forwardmost tip point and a plurality of front surfaces with outer and inner cutting edges. An outer rake surface adjacent to each outer cutting edge has a positive outer rake angle, and an inner rake surface adjacent to each inner cutting edge has a negative inner rake angle. Each outer rake surface is disposed on a head flute intersecting one of the leading edges, and each inner rake surface is disposed on a gash intersecting one of the head flutes. Each gash extends to a gash path end point located a first distance axially rearward of the tip point, and the first distance is greater than thirty percent of the cutting diameter.

A drill bit includes a shank, an intermediate portion with a helical flute, and a multi-stepped tip portion extending along the axis. The tip portion includes a cutting tip with a pair of primary cutting edges extending radially outward from the axis, a plurality of steps each having an elongated portion and a tapered portion tapered outward from the elongated portion relative to the axis. The elongated portions progressively increase in diameter from the cutting tip to the intermediate portion. The elongated portion of each step has an axial relief tapered inward toward the axis. A frontmost elongated portion has a first axial relief at a first angle relative to the central axis and a rearmost elongated portion has a second axial relief at a second angle greater than the first angle. The drill bit may be used as a pilot bit together with a holesaw in a system.

A cutting head rotatable about a central axis, comprising a tip portion and an intermediate portion. The tip portion has an axially forwardmost tip point contained in the central axis and three axially forward facing front surfaces forming three chisel edges extending axially rearwardly away from the tip point, each front surface having a radially extending cutting edge comprising a secondary cutting-edge portion extending radially outwardly from one of the chisel edges, and a primary cutting-edge portion extending radially outwardly therefrom. Each primary cutting-edge portion is contained in an imaginary annular ring surface having an annular ring width spanning at least radially inner and outer end points thereof. In a front-end view of the cutting head, each primary cutting-edge portion is concave, and radial planes intersect the imaginary annular surface to form imaginary rectilinear lines, each having a length equal to the annular ring width.

A drill (1) is provided with a thinning edge (7), a gash portion (8), a coolant passage, and an oil hole (12). The thinning edge (7) is provided at a leading end portion of a body (3), and extends toward a chisel portion (9) from an inner end (51) of a cutting edge (5). A ridge line between the gash portion (8) and the flank (6) extends in a circular arc shape from an inner end of the thinning edge (7) toward an outer peripheral surface (31) of the body (3). The coolant passage is provided inside a shank and the body (3), and extends from a rear end portion of the shank toward the leading end portion of the body (3). The oil hole (12) is provided at a gash face (81) of the gash portion (8) and is an outlet of the coolant passage.

According to one implementation, a drill includes the first cutting edges, the second cutting edges and a deflection reducer. The first cutting edges drill a prepared hole to a workpiece. The first cutting edges are formed in a tip side of the drill. The first point angle and each first relief angle of the first cutting edges continuously or intermittently decrease from the tip side toward a rear end side of the drill. The second cutting edges finish the prepared hole. The second cutting edges are formed at positions away in the rear end side from the first cutting edges. The second cutting edges have the second relief angles at a maximum diameter position. The deflection reducer reduces deflection of the second cutting edges. The deflection reducer is formed between the first cutting edges and the second cutting edges. The deflection reducer is inserted into the prepared hole.

A cutting head rotatable about a first axis, comprising an intermediate portion and a tip portion. The intermediate portion has a plurality of leading edges defining a cutting diameter, and the tip portion has an axially forwardmost tip point and a plurality of front surfaces with outer and inner cutting edges. An outer rake surface adjacent to each outer cutting edge has a positive outer rake angle, and an inner rake surface adjacent to each inner cutting edge has a negative inner rake angle. Each outer rake surface is disposed on a head flute intersecting one of the leading edges, and each inner rake surface is disposed on a gash intersecting one of the head flutes. Each gash extends to a gash path end point located a first distance axially rearward of the tip point, and the first distance is greater than thirty percent of the cutting diameter.