Abstract: A cutting insert according includes a first surface and a cutting edge. The first surface includes a first inclined surface and a projection. The first inclined surface includes a first region located close to a first corner portion, a second region located close to a second corner portion, and a third region located between the first region and the second region. The projection includes a first projection located close to the first corner portion and a second projection located close to the second corner portion. A first top portion of the first projection is located closer to the first corner portion than a first boundary portion between the first region and the third region, and a second top portion of the second projection is located closer to the second corner portion than a second boundary portion between the second region and the third region.

Abstract: In an embodiment, a cutting insert includes an upper surface, a front end surface, and a front cutting edge. The upper surface includes a first protrusion and a second protrusion, and a first surface, a second surface, and a third surface, each of which is located between the first protrusion and the second protrusion. The first surface is inclined downward at a first inclination angle. The second surface is inclined upward at a second inclination angle. The third surface is inclined upward at a third inclination angle. The second surface is located lower than an upper end of each of the first protrusion and the second protrusion. The third surface extends further upward than the upper end of each of the first protrusion and the second protrusion. The third inclination angle is smaller than the second inclination angle.

Abstract: A cutting insert according includes a first surface and a cutting edge. The first surface includes a first inclined surface and a projection. The first inclined surface includes a first region located close to a first corner portion, a second region located close to a second corner portion, and a third region located between the first region and the second region. The projection includes a first projection located close to the first corner portion and a second projection located close to the second corner portion. A first top portion of the first projection is located closer to the first corner portion than a first boundary portion between the first region and the third region, and a second top portion of the second projection is located closer to the second corner portion than a second boundary portion between the second region and the third region.

Abstract: In an embodiment, a cutting insert includes an upper surface, a front end surface, and a front cutting edge. The upper surface includes a first protrusion and a second protrusion, and a first surface, a second surface, and a third surface, each of which is located between the first protrusion and the second protrusion. The first surface is inclined downward at a first inclination angle. The second surface is inclined upward at a second inclination angle. The third surface is inclined upward at a third inclination angle. The second surface is located lower than an upper end of each of the first protrusion and the second protrusion. The third surface extends further upward than the upper end of each of the first protrusion and the second protrusion. The third inclination angle is smaller than the second inclination angle.

Abstract: A holder according to one embodiment has a rod shape and includes a head portion located at a front end side. The head portion includes an upper jaw portion and a lower jaw portion located at a front end, an insert pocket located between the upper jaw portion and the lower jaw portion, a first wall surface located at an upper surface of the upper jaw portion and inclined in an extending manner from one side surface side, a second wall surface located closer to a rear end side than the first wall surface and inclined upward, a concave-shaped third wall surface located closer to the rear end side than the second wall surface, and a fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface. The third wall surface is concave downward from an upper end of the second wall surface.

Abstract: A holder according to one embodiment has a rod shape and includes a head portion located at a front end side. The head portion includes an upper jaw portion and a lower jaw portion located at a front end, an insert pocket located between the upper jaw portion and the lower jaw portion, a first wall surface located at an upper surface of the upper jaw portion and inclined in an extending manner from one side surface side, a second wall surface located closer to a rear end side than the first wall surface and inclined upward, a concave-shaped third wall surface located closer to the rear end side than the second wall surface, and a fourth wall surface inclined upward as the fourth wall surface extends away from the third wall surface. The third wall surface is concave downward from an upper end of the second wall surface.