A drill bit includes a cutting edge formed at a distal end of a drill bit body, a chip ejection flute having a rake face on a side adjacent to the distal end of the drill bit body, the chip ejection flute extending from the rake face toward a proximal end of the drill bit body, and a chip guide part provided, on the rake face, extending along an extending direction of the chip ejection flute. The chip guide part has at least one guide groove extending along the extending direction of the chip ejection flute from a ridge portion where the cutting edge is provided or from near the ridge portion.

A rotary cutting tool includes a tool body including a chip flute portion having a plurality of helical chip flutes separated by lobes. In one aspect, a tunable vibration absorber assembly is disposed within a cavity formed in the chip flute portion. In another aspect, the tunable vibration absorber assembly is disposed within a cavity of a replaceable cutting head. In each aspect, the tunable vibration absorber assembly includes one or more tunable absorber masses, a resilient material between the one or more absorber masses and the cavity, and one or more connecting members for preventing relative angular displacement of the one or more tunable absorber masses. The one or more tunable absorber masses are suspended only by the resilient material, thereby enabling the tunable vibration absorber assembly to be tuned to a desired frequency for suppressing torsional vibration of the rotary cutting tool during a cutting operation.

A tapered countersink drill bit includes at least two screwing knifes and at least one two screwing trenches and a rod body; a length of an edge of the left lateral side of each screwing knife being shorten than that of an edge of the right lateral side thereof; each screwing knife including a front drilling head; a tapered portion formed at a backside of the front drilling head; a rear drilling head formed at a backside of the tapered portion; the screwing angle of each screwing knife being identical from the front drilling head to the rear drilling head; and a screwing angle of each screwing trench being identical from the front drilling head to the rear drilling head; a width between two adjacent knifes at a front end of the rear drilling head being longer than a width between two knifes at rear ends of two rear drilling head.

A drill may include a main body having a bar shape extending from a first end to a second end. The main body may be rotatable around a rotation axis. The main body may include a cutting edge, a first flute extending from the cutting edge, and a second flute extending from the first flute. The first flute may include, in a cross section orthogonal to the rotation axis, a first portion having a concave curvilinear shape located at a rear side in a rotation direction, and a second portion having a convex curvilinear shape located at a front side in the rotation direction. The second flute has a concave curvilinear shape from an end portion located at a front side in the rotation direction to an end portion located at a rear side in the rotation direction in the cross section.

A small-diameter drill in which is a double margin having a diameter of 2 mm or less and a ratio of a margin length to a diameter of 3 or more, in which the margin length L in an axial direction from an outer peripheral end of a cutting edge to the rear ends of first and second margin parts and a ratio L/D to a diameter D are 3 or more, in which at least a surface of a chip discharge groove is provided with a hard coating made of nitride, in which a surface of the hard coating in the chip discharge groove has skewness (Ssk) defined in ISO25178 of less than 0, and in which the number of droplets having an equivalent circle diameter of 1.0 m or more is 5 or less per 100 m.sup.2 in cross-section observation of the hard coating.

A rotary tool may include a body, the body may include a cutting edge and a first groove. The first groove may include a first region having a first helix angle, a second region having a second helix angle, a third region having a third helix angle, a fourth region having a fourth helix angle, and a fifth region having a fifth helix angle. The fourth helix angle and the fifth helix angle may each decrease from a side of a first end toward a second end. A decreasing range of a value of the fourth helix angle of the fourth region may be less than a decreasing range of a value of the fifth helix angle of the fifth region. A length of the fourth region may be greater than a length of the fifth region.

A vertical-edge double-step sawtooth cutter for preparing high-quality holes of composite material and thereof hybrid stack structure, and has three parts which are a major cutting edge region A, a minor cutting edge region B and a shank region C. The minor cutting edge region B comprises a step vertical-edge region D and a sawtooth cutting region E. This has the step structure and the sawtooth structure which is distributed in the first step, has a recutting function at the inlet and a reverse cutting function at the outlet in the direction opposite to the main cutting motion. The cutter has the vertical edge structure distributed in the second step, and the angle of the second step is a negative value, thereby realizing chip breaking and crushing, reducing scratch to the upper-layer composite material and metal hole walls.

An orbital drill includes a drilling portion, a shank portion, and a neck portion between the drilling portion and the shank portion. The drilling portion includes one or more right-handed spiral flutes with cutting edges having a positive axial rake angle for positive cutting action while orbiting into a material. The right-handed spiral flutes have a positive radial and axial rake angle. The drilling portion also includes one or more left-handed spiral flutes located rearward of the one or more right-handed spiral flutes with cutting edges having a positive axial and radial rake angle for positive cutting action while orbiting back out of the material and removing any material left in the hole, thereby eliminating a separate reaming operation. A method of machining a workpiece using the orbital drill is also disclosed.

A drilling tool, in particular a rock drilling tool, for a portable machine tool, includes an axis of rotation, at least one spiral path, and at least one wear surface transition. The at least one spiral path is coiled about the axis of rotation along the axis of rotation and includes at least one wear surface having at least one bandwidth. There is a change in the at least one bandwidth of the at least one wear surface at a position of the at least one wear surface transition.

An orbital drill includes a drilling portion, a shank portion, and a neck portion between the drilling portion and the shank portion. The drilling portion includes one or more right-handed spiral flutes with cutting edges having a positive axial rake angle for positive cutting action while orbiting into a material. The right-handed spiral flutes have a positive radial and axial rake angle. The drilling portion also includes one or more left-handed spiral flutes located rearward of the one or more right-handed spiral flutes with cutting edges having a positive axial and radial rake angle for positive cutting action while orbiting back out of the material and removing any material left in the hole, thereby eliminating a separate reaming operation. A method of machining a workpiece using the orbital drill is also disclosed.