Any three axis mill that is capable of helical interpolation can be used for thread milling. To produce internal threads, drill the minor thread diameter to its appropriate size. Then, position the thread mill to the required depth. Next, mill either the 'X' or 'Y' axis to the required thread pitch diameter. With small sizes and with difficult-to-cut material, it is best to ramp on to the paper size and it may be necessary to remove the material in several passes. A right-hand thread is produced by orbiting in a counterclockwise direction while bringing the 'Z' axis up by one pitch per 360 degrees. A left-hand thread is produced by orbiting in a clockwise direction while bringing the 'Z' axis up by one pitch per 360 degrees. The entire process can also be achieved by interpolating in a downward direction. This requires the tool to be positioned one pitch up from its proper thread depth and then interpolated clockwise for right-hand threads or counterclockwise for left-hand threads.

NPT threads are produced the same way except that it is not necessary to ream the taper. Also, if the tool is interpolated in an upward direction, it must be programmed to feed out on the taper.

With external threads the major diameter must first be milled to size. Right-hand threads are cut by interpolating up and in a counterclockwise direction. Left-hand threads are cut by interpolating up and in a clockwise direction. The same threads can be produced by interpolating down and changing the orbiting direction.