A sewing machine part is a component of a sewing machine that helps it to function. The three parts that make up a sewing machine are the CAM, the TREADLE, and the PEDAL. The CAM is a rotating disc with an irregular shape that helps to control the speed of the machine. The TREADLE is a foot-operated lever that is used to start and stop the machine. The PEDAL is a foot-operated switch that controls the speed of the machine. All three of these parts are essential for a sewing machine to work properly.