A hobbing machine is used to produce gears by cutting teeth into a rotating metal blank using a threaded cutting tool called a hob. Both the cutter and the workpiece spin together in a carefully timed relationship which allows the gear teeth to form gradually instead of being cut one at a time. This continuous motion is what gives hobbing its speed and consistency. As the hob advances across the surface of the blank it removes material in small increments until the full tooth shape is created. T