Abstract: This invention discloses a method and an apparatus for grinding and polishing up a rod-like object which has such a comparatively small diameter that the rod is pliable when subjected to usual grinding. Upon grinding, it is placed on a horizontal, rotatable roll with a surface having great frictional resistance and held by a pair of parallel, opposed guide plates on both sides, where it is made to rotate by the rotation of the roll while a rotating grindstone is being pressed on it. Uniform grinding can be made by moving the grindstone and the rod-like object relative to each other along a gap between the parallel, opposed guide plates.

Abstract: A roller used for a roller conveyor which includes an outer cylinder of the roller supported by a pneumatic bearing. The roller also includes a fixed shaft having a path for letting air pass through in the center thereof, and annular members fitted on the fixed shaft, the outer cylinder covering the shaft and annular members leaving a narrow gap around the annular members. The path for letting air pass through the shaft and the narrow gap communicate with each other by way of holes and a groove made on the annular members. Therefore, the introduced air can pass through the holes and the groove and then fill the narrow gap to such an extent that the wall of the outer cylinder never comes into contact with the annular members, the thin layer of air in the gap functioning as the pneumatic bearing.