A method for giving specific shape to metal parts with revolving cutting tools, mostly known as milling cutters. It is faster than other methods of shaping. Although milling cutters may be used in a lathe, they are more often employed in a milling machine. These machines are of two types, those with vertical spindles and those with horizontal ones. Milling cutters are made to produce clock wheels or pinions, and they cut or 'gash' one tooth space at a time in the wheel or pinion blank. When cutting a wheel with a milling cutter, the milling machine can be arranged so that the revolving cutter moves through the stationary blank; alternatively, the blank can be mounted in an attachment which moves it in the path of the revolving cutter. Hobbing is a quicker and more accurate way of cutting gears; hobs are cutters in the form of a worm, the cutting edges being formed by flutes across the worm thread. The work and the hob are revolved together, the two often being suitably geared by the hobbing machine.