A plurality of helical grooves are formed in a workpiece having a cylindrical shape. Each of grooves is divided into a first portion including an end portion on a first end side of the workpiece and a second portion including an end portion on a second end side of the workpiece. A method of manufacturing a screw rotor of a screw compressor includes attaching a first end of the workpiece to a holder of a machine tool, finishing the first portion of each of the plurality of helical grooves by cutting, detaching the workpiece from the holder, attaching a second end of the workpiece detached from the holder to the holder, and finishing the second portion of each of the plurality of helical grooves by cutting.

A whirling tool (21), in particular for cutting a thread, includes a body with cutting teeth integrally machined thereon (23; 47, 51). Inaccuracies caused by mounting cutting teeth on the tool are avoided thereby.

A manufacturing method of a gear includes: rotating a rod-shaped workpiece around a first axis; rotating a tool having a cutting edge around a second axis at a twisted position with respect to the first axis. In a plane perpendicular to the first axis, the workpiece is rotated around the first axis and the workpiece and the tool are relatively moved in the direction parallel to the first axis at the speed synchronized with the rotation speed of the workpiece such that a contour line of the cutting edge of the tool is in rolling contact with a target contour line, which is a contour line of the spiral tooth groove to be formed, at a predetermined point of the target contour line or an extension line of the target contour line without slipping, and rotates while sliding with respect to the target contour line.

A constant rake planar cutting edge fluted drill bit and a method of manufacturing the same. The drill bit includes a planar cutting face formed at the tip end of the bit by a motion of a rotating machining wheel respective to a stationary blank in a first step. Once the cutting face is formed, the blank is rotated and translated in a direction parallel to an elongated axis, during which the rotating machining wheel creates a flute. Upon completion of the first flute, the bit is rotated accordingly and the processes are repeated to create each subsequent planar cutting face and respective flute. The process can also be completed in a slightly modified version of a reverse process, fabricating a flute prior to formation of the planar cutting face of the bit.

A constant rake planar cutting edge fluted drill bit and a method of manufacturing the same. The drill bit includes a planar cutting face formed at the tip end of the bit by a motion of a rotating machining wheel respective to a stationary blank in a first step. Once the cutting face is formed, the blank is rotated and translated in a direction parallel to an elongated axis, during which the rotating machining wheel creates a flute. Upon completion of the first flute, the bit is rotated accordingly and the processes are repeated to create each subsequent planar cutting face and respective flute. The process can also be completed in a slightly modified version of a reverse process, fabricating a flute prior to formation of the planar cutting face of the bit.