A drill includes a bar-shaped drill body, a major cutting edge which is located at a front end of the drill body and has a straight-line region in a front view, a rake surface located along the major cutting edge, and a chip discharge flute being extended spirally around a rotation axis of the drill body in a direction from the rake surface toward a rear end of the drill body. The rake surface has a flat region located along the straight-line region.

An instrument comprising a shank and a working portion, the working portion having a tip and a plurality of flutes being defined by at least two lands having a land margin; wherein the working portion has a parabolic cross-section defining opposing convexed surfaces extending between at least two opposing land margins.

In an indexable drill, a cutting insert having a cutting edge is detachably mounted on an insert mounting seat of a drill main body. The insert mounting seat has a bottom surface facing a tip side of a drill main body, and a wall surface extending to the tip side and facing a drill rotation direction. The cutting insert has a seating surface seated on the bottom surface toward a rear end side of the drill main body, a contact surface coming into contact with the wall surface toward a side opposite to the drill rotation direction, a projection portion projecting to the side opposite to the drill rotation direction on a tip side of the contact surface, and a mounting hole penetrating the seating surface from a tip flank.

A chip discharging flute is formed in a tip outer peripheral portion of a drill body rotated around an axis in a drill rotation direction. A cutting edge is formed in an intersection ridgeline portion between a wall surface of the chip discharging flute facing the drill rotation direction and a tip flank. The cutting edge includes a main cutting edge portion extending from an inner peripheral side toward an outer peripheral side of the drill body, and a cutting edge shoulder portion extending from an outer peripheral end of the main cutting edge portion to an outer periphery of the drill body, and is subjected to honing. Compared to the outer peripheral end of the main cutting edge portion, in an outer peripheral end of the cutting edge shoulder portion, a true rake angle is increased on a negative rake angle side, and a size of the honing decreases.

A rotary tool according to a non-limiting aspect includes a body having a rotation axis and extending from a first end to a second end. The body including: a first part including the first end; a second part located closer to a second end than the first part and having a larger outside diameter than the first part; a cutting edge located at a side of the first end; a ridge portion located in the first part and the second part, connected to the cutting edge and helically extending from the cutting edge toward the second end; and a flute located along the ridge portion. The flute includes: a first flute located at the first part and having a first helix angle; and a second flute located at the second part and having a second helix angle. The second helix angle is smaller than the first helix angle.

A cutting tool has a rake face and a flank face. The flank face is provided with a coolant supply hole. A ridgeline between the rake face and the flank face forms a cutting edge. An outer shape of the coolant supply hole in a cross section orthogonal to an axis includes a first portion facing the cutting edge, and a second portion opposite to the cutting edge when viewed from the first portion. The first portion has a concave portion extending toward the second portion. The concave portion is defined by a first side portion and a second side portion facing each other, and a bottom continuous with both the first side portion and the second side portion. In the cross section, an angle formed by a tangent of the first side portion and a tangent of the second side portion is not more than 160°.

A method of producing a drill has a step of preparing a workpiece to be processed to produce a drill, and a step of forming a ground groove. The workpiece has a cutting blade, a chip discharge flute helically extending, and a rake surface which have been formed therein. The drill is rotated around a drill axial center. The formation step rotates a rotary whetstone around its whetstone axial center, and grinds the rake surface to form the ground groove along the chip discharge flute. The formation step uses the rotary whetstone so that the whetstone axial center intersects a longitudinal direction of the chip discharge flute. The rotary whetstone has a rotating body shape projecting in a radial outward direction of the rotary whetstone axial center and around the rotary whetstone axial center.

A drilling tool, in particular a rock drilling tool, for a portable machine tool includes a drill head, a drill shaft connected to the drill head, and a rotational axis. The drill head in one embodiment is a hard metal drill head, and the drill shaft in one embodiment is connected integrally with the drill head. The drill shaft is configured as one piece, has a guide section with guide groove winding in a spiral-shaped about the drill shaft for transporting away drilling dust, and has a securing section that is configured to detachably secure the drilling tool to a machine tool. The guide section has a diameter reinforcement at a drill head support region of the guide section neighboring the drill head.

An insert includes a main body extending from a first end toward a second end. The main body includes a cutting edge, a rake face, and a flute. In the rake face, a second rake angle of a second surface region positioned closer to the second end than a first surface region connected to the cutting edge is smaller than a first rake angle of the first surface region. A third rake angle of a third surface region is smaller than the second rake angle, the third surface region being adjacent to the flute rearward in a rotational direction and on an outer peripheral side of the main body.