Abstract: A tap having a main body having a crest, a heel, and an outer circumference is disclosed. The tap main body has a male screw part at the crest side. At this male screw part, a plurality of grooves opening to the crest and the outer circumference of tap main body is formed. A tap main body has a cutting edge at each ridge part defined by a wall of said plurality of grooves and an outer circumference of a male screw part. These cutting edges each have a crest part and a heel part. The crest part of at least one cutting edge has an axial rake angle which differs from an axial rake angle of the crest part of another cutting edge.

Abstract: A rotary cutting tool includes a body having a cutting portion and an axis of rotation therethrough. The body has a plurality of helical flutes formed in a circumferential surface of the cutting portion in circumferentially spaced relation to one another and extending helically axially of the cutting portion so as to define a plurality of helical lands of a generally uniform land width spaced circumferentially of the cutting portion from one another. The body has a plurality of helical peripheral cutting edges each defined by a portion of an inner surface of a respective one of the helical flutes facing in a direction of rotation of the body and a surface of the land adjacent to the portion of the inner surface. At least one of the peripheral cutting edges has a helix angle different from helix angles of the other peripheral cutting edges. The peripheral cutting edges are equally spaced circumferentially of the body in at least one plane disposed perpendicularly to the axis of rotation of the body.

Abstract: An insert rotary cutting tool includes a tool body of a generally circular cross-section having an axis of rotation therethrough and having an outer periphery. The cutting tool has plural groups of cutting inserts releasably mounted on the outer periphery of the body with the groups being spaced circumferentially of the body from each other. The inserts of each group are displaced circumferentially of the body and spaced axially of the body. Each of the inserts has a plurality of main cutting edges and is disposed in such a manner that one of the main cutting edges is indexed in a peripheral cutting position to serve as a peripheral cutting edge. The indexed peripheral cutting edges of the inserts are in series axially of the body as viewed circumferentially of the body. The indexed peripheral cutting edges of the inserts of each group have foremost ends disposed on a common helical line extending helically axially of the body.