Abstract: A workpiece-holding plug has six sector-shaped segments that expand outwardly in a radial direction when in use and in contact with a lathe center. The segments have tapered outer wall portions which assume a precise cylindrical shape when the plug is expanded so that the central axis of the lathe center is maintained in precise concentric relationship to the central axis of the workpiece. The plug is of a particular construction which ensures that each of the segments shifts radially outwardly an equal distance, and yet has sufficient resiliency for self-contraction when the work operation is completed so that the plug may be readily removed from the workpiece. The plug has particular utility for holding a press roller on a lathe during reconditioning of the outer rubber surface of the roller.