A gear shaper is a machine tool for cutting the teeth of an internal gear. The name shaper relates to the fact that the cutter engages the part on the forward stroke and pulls away from the part on the return stroke, just like the clapper box on a planer shaper. To cut external teeth, a different machine called a hobbing machine is used. A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by the selective removal of metal. ... Spur gears found on a piece of farm equipment. ... In woodworking, a planer is a machine used to plane wood. ... A hobbing machine is a special form of milling machine that mills gears. ...