A method for making a robot pivot arm assembly includes forming from a rigid, machinable material a circular disk, and forming a circular aperture through the center of the disk. An outer bearing track is formed integrally in the inside surface which defines the aperture, and the apertured disk is positioned in a machining device with a fixturing portion that engages the outer bearing track. An integral outer race, an arm and a gear segment with teeth are then machined into the disk to form the outer portion of the pivot arm assembly. An inner race with an inner bearing track is positioned inside the integral outer race, and rolling bearing elements are inserted into the first and second bearing tracks.