A cam assembly is disclosed which includes a cam having a first cam pivot, a second cam pivot, and a machine shaft guide; a range plate which is engageable with the cam; a belt connected to the cam; and a machine shaft connected to the range plate. The first cam pivot defines the motion of a first arc and the second cam pivot guide defines the motion of a second arc as the cam is adjusted. A method of using a cam assembly is also disclosed which includes engaging an adjustor on a cam; releasing a connection between the cam and a range plate; rotating the cam; releasing the adjustor; and securing a connection between the cam and the range plate.