A reamer is rotated about a central axis and has, in a direction along a central axis, a tool front end and a tool rear end that is an end opposite to the tool front end. The reamer includes a blade on a tool front end side. The blade has, on a circumferential surface, a chamfered cutting edge located on the tool front end side, a circumferential cutting edge contiguous to an end of the chamfered cutting edge on a tool rear end side, and a margin that is a surface contiguous to the circumferential cutting edge. The circumferential cutting edge includes a front end portion between a first position and a second position, the first position being an end on a chamfered cutting edge side, the second position having a distance of 1 mm from the first position in a direction of extension of the circumferential cutting edge.

A reamer is rotated about a central axis and has, in a direction along a central axis, a tool front end and a tool rear end that is an end opposite to the tool front end. The reamer includes a blade on a tool front end side. The blade has, on a circumferential surface, a chamfered cutting edge located on the tool front end side, a circumferential cutting edge contiguous to an end of the chamfered cutting edge on a tool rear end side, and a margin that is a surface contiguous to the circumferential cutting edge. The circumferential cutting edge includes a front end portion between a first position and a second position, the first position being an end on a chamfered cutting edge side, the second position having a distance of 1 mm from the first position in a direction of extension of the circumferential cutting edge.

An oil hole reamer includes an oil passage extending inside a tool main body along an axis of the tool main body, and an oil hole extending radially outward from the oil passage to an outer circumference of the tool main body. An oil outlet of the oil hole is formed to be open toward a position corresponding to a corner at which a tip cutting edge intersects an outer-circumference cutting edge and to cause at least part of the oil outlet to be open to the outer-circumference flank face.

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 reamer includes a core, a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material, and a margin provided on a rear side of each the plurality of outer-circumference cutting edges in a rotational direction. A distance from an axis of rotation to a position of a center of gravity of the reamer is greater than 0.01 mm and not greater than 0.5 mm.

A reamer includes a core, a plurality of outer-circumference cutting edges provided on an outer circumference of the core and made of a hard tool material, and a margin provided on a rear side of each the plurality of outer-circumference cutting edges in a rotational direction. A distance from an axis of rotation to a position of a center of gravity of the reamer is greater than 0.01 mm and not greater than 0.5 mm.

An oil hole reamer includes an oil passage extending inside a tool main body along an axis of the tool main body, and an oil hole extending radially outward from the oil passage to an outer circumference of the tool main body. An oil outlet of the oil hole is formed to be open toward a position corresponding to a corner at which a tip cutting edge intersects an outer-circumference cutting edge and to cause at least part of the oil outlet to be open to the outer-circumference flank face.

A multi-edge reamer has a cutting region having a main body with a central axis. A first number of first cutters and a second number of second cutters extend from the main body. Each first cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding first cutter and has a first width. Each second cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding second cutter and has a second width. The first width is greater than the second width, the first number of first cutters is greater than the second number of second cutters, and all of the first cutters directly adjoin one another when seen in the circumferential direction so as to be arranged in a continuous group.

A multi-edge reamer has a cutting region having a main body with a central axis. A first number of first cutters and a second number of second cutters extend from the main body. Each first cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding first cutter and has a first width. Each second cutter has a cutting edge and an adjoining circular grinding chamfer which forms a guide region for a corresponding second cutter and has a second width. The first width is greater than the second width, the first number of first cutters is greater than the second number of second cutters, and all of the first cutters directly adjoin one another when seen in the circumferential direction so as to be arranged in a continuous group.

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.