Rotary tool and method for manufacturing machined product

A rotary tool, comprising:

• a base extended along a central axis from a first end to a second end,
• the base comprising
• a first part including the first end, and
• a second part which is located closer to the second end than the first part and has a larger outer diameter than the first part,
• the first part comprising
• a plurality of first cutting edges located on the first end,
• a plurality of first flutes extended from the plurality of first cutting edges, respectively, toward the second end, and
• a first portion defined by an entire portion located between two first flutes of the plurality of first flutes adjacent to each other in a circumferential direction,
• the second part comprising
• a second cutting edge located on an end part of the second part and closer to the first end than the second end, and
• a second flute extended from the second cutting edge toward the second end,
• wherein
• in a first cross section of the first part orthogonal to the central axis,
• each of the plurality of first flutes comprises a first bottom part having a first circular arc shape, the first bottom part including a portion located closest to the central axis, and
• an imaginary circle overlapping with the first bottom part is a first imaginary circle, and a center of the first imaginary circle is located outside a circumscribed circle of the first part,
• in a second cross section of the second part orthogonal to the central axis,
• the second flute comprises a second bottom part having a second circular arc shape, the second bottom part including a portion located closest to the central axis, and
• an imaginary circle overlapping with the second bottom part is a second imaginary circle, and a center of the second imaginary circle is located inside a circumscribed circle of the second part, and
• the second circular arc shape of each of the plurality of second flutes is different than the first circular arc shape of each of the plurality of first flutes,
• in the first cross section of the first part orthogonal to the central axis,
• an entirety of the first portion is bounded by
• the first circular arc shape of each first bottom part of the two first flutes of the plurality of first flutes adjacent to each other in the circumferential direction,
• an outer periphery of the first part, and
• an imaginary line connecting a respective end of each circular arc shape of the two first flutes adjacent to each other in the circumferential direction, each end being a furthest part of each circular arc shape from the outer periphery between the two first flutes adjacent to each other in the circumferential direction,
• the first circular arc shapes of the two first flutes of the plurality of first flutes adjacent to each other in the circumferential direction intersect the outer periphery of the first part,
• a length of the imaginary line defines a largest width of the entirety of the first portion, and
• a width of the entirety of the first portion continuously becomes narrower in a direction going away from the central axis,
• the width of the entirety of the first portion is measured perpendicular to a radial line extending from the central axis and is measured between the first circular arc shapes of the first bottom parts of the two first flutes adjacent to each other in the circumferential direction, and
• each of the plurality of first flutes comprises only the first bottom part having the first circular arc shape.