| CPC B23B 51/06 (2013.01) [B23C 5/10 (2013.01); B23B 2250/12 (2013.01); B23C 5/28 (2013.01)] | 13 Claims |

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1. A rotary tool, comprising:
a base which has a bar shape and is extended along a rotation axis from a first end toward a second end,
wherein
the base comprises
a cutting part including the first end,
a shank part located closer to the second end than the cutting part, and
a flow path which is located inside the base and is extended along the rotation axis,
the cutting part comprises
an outer peripheral surface,
a first cutting edge extended from the first end toward the outer peripheral surface,
a first flute spirally extended from the first cutting edge toward the second end, and
a first ridgeline formed by the first flute and the outer peripheral surface adjacent to the first flute on a rear side in a rotation direction of the rotation axis,
the flow path comprises
a main flow path extended from a side of the second end toward the first end, and
a first sub flow path extended from the main flow path toward the second end,
the first sub flow path comprises a first opening that opens into the first flute,
a first angle formed by the rotation axis and the first sub flow path is smaller than a helix angle formed by the rotation axis and the first ridgeline,
the first ridgeline comprises
a first portion, and
a second portion located closer to the second end than the first portion, and
a first helix angle formed by the rotation axis and the first portion is different from a second helix angle formed by the rotation axis and the second portion.
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