A cam mechanism incorporating a highly precise bearing structure that improves the dynamic stability of the cam mechanism's rotating output component. Relevant structures consist of a worm gear driven rotating shaft driving a rotating output shaft supported by a cross roller bearing assembly incorporating V-shaped inner and outer bearing races that sandwich and ride over a set of rollers. Of particular note is that the outer or inner bearing race may be formed as a groove machined directly into the circumferential surface of the output shaft. Because the outer bearing race is a ring-shaped structure that concentrically surrounds the rotating output shaft, the output shaft and bearing races can be machined simultaneously as a single workpiece to assure a high degree of concentricity between the shaft and bearing races.