A rotary tool may include a base. The base may be extended from a first end to a second end. The base may include a first part and a second part. The first part may include the first end. The second part may have a larger outer diameter than the first part. The first part may include a first flute. The second part may include a second flute. In a first cross section of the first part, the first flute may include a first bottom part. A center of a first imaginary circle overlapping with the first bottom part may be located outside a circumscribed circle of the first part. In a second cross section of the second part, the second flute may include a second bottom part. A center of the second imaginary circle overlapping with the second bottom part may be located inside a circumscribed circle of the second part.

A rotary tool may include a base. The base may be extended from a first end to a second end. The base may include a first part and a second part. The first part may include the first end. The second part may have a larger outer diameter than the first part. The first part may include a first flute. The second part may include a second flute. In a first cross section of the first part, the first flute may include a first bottom part. A center of a first imaginary circle overlapping with the first bottom part may be located outside a circumscribed circle of the first part. In a second cross section of the second part, the second flute may include a second bottom part. A center of the second imaginary circle overlapping with the second bottom part may be located inside a circumscribed circle of the second part.

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.

There is provided a machining assembly and cutting insert for machining metal or like workpieces, wherein the cutting insert body has a cutting end. The cutting end comprises at least one cutting edge and at least one cutting lip formed adjacent the at least one cutting edge. The at least one cutting lip includes at least one cutting protrusion and associated chip cutting edge to split the chip formed by the at least one cutting edge, for producing chips during machining which are of a width that is sufficiently reduced to allow proper evacuation or removal.

This disclosure relates to a metal-cutting machine tool with a base body, which is rotatable about an axis of rotation relative to a workpiece to be machined, at least one plate seat disposed outside the axis of rotation on the base body and a cutting insert, which is inserted into the plate seat and held therein by at least one fastening means and which is provided with a coating, at least in the area of its cutting edge. In order to compensate for positional tolerances, according to this disclosure the plate seat comprises a positioning surface oriented toward the axis of rotation, and the cutting insert has a reference surface lying against the positioning surface and facing away from the axis of rotation, for radially determining the position of its cutting edge, wherein the coating is also applied to the reference surface.

Multiple grooves are provided on the outer circumferential surface of the body of an insert holder. A first holding surface of an insert first holding part, which is inserted between a groove bottom and a first protrusion, and a first protrusion surface of the first protrusion make surface contact and said surfaces are sloped so as to approach the groove bottom as the first end is approached. A second holding surface of an insert second holding part, which is inserted between the groove bottom and a second protrusion, and a second protrusion surface of the second protrusion make surface contact and said surface are sloped so as to approach the groove bottom as the second end is approached.

Multiple grooves are provided on the outer circumferential surface of the body of an insert holder. A first holding surface of an insert first holding part, which is inserted between a groove bottom and a first protrusion, and a first protrusion surface of the first protrusion make surface contact and said surfaces are sloped so as to approach the groove bottom as the first end is approached. A second holding surface of an insert second holding part, which is inserted between the groove bottom and a second protrusion, and a second protrusion surface of the second protrusion make surface contact and said surface are sloped so as to approach the groove bottom as the second end is approached.

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.