Abstract: The workstock may comprise a tailstock having a slide which releasably carries a workpart center and which includes a center ejector member independently movable in the slide. The slide is mounted in a housing for axial motion toward and away from a headstock center to load and unload a workpart therebetween. The axial position of the slide as well as the center ejector member is monitored by position sensors to provide status of the tailstock center and workpart. The workpart center is loosened by the ejector member in the slide when the ejector member is positioned from a retracted position relative to the pocket to a center eject position toward the pocket so that a robot may remove the center and substitute another center to hold a different workpart.