The holder is die cast into a steel ball used for the precision bearing as the core, then the shank is specially welded to the holder. *This manufacturing process is advantageous in that the mirror surface of the steel ball can be exactly duplicated on the holder spherical interior, and that high lubrication performance is achieved as grease pockets are provided at the top and bottom of the spherical section, over the entire surface of which the ball and holder contact one another. High lubrication performance results in high wear resistance. (*This unique manufacturing process allows the mirror surface of the steel ball to be exactly duplicated on the holder spherical interior, thereby making it possible for the holder sphere and ball to contact one another over the entire surface. Grease pockets provided at the top and bottom of the spherical section ensure high lubrication performance and high wear resistance.)