Abstract: A manufacturing method is provided for forming a hollow cylinder with a bottom which may be employed in rotary head drums of magnetic recording and reproduction systems such as video tape recorders and digital audio tape recorders.The manufacturing method includes pressing a single circular plate to form the hollow cylinder, thrusting an end of a side wall of the hollow cylinder in a direction substantially parallel to the side wall in a press die so as to adjust the thickness of the side wall to be uniform, and machining an outer surface of the side wall of the hollow cylinder so as to have a given surface roughness and a given roundness.

Abstract: With a device for reciprocating a cutting tool in small steps, the cutting tool is reciprocated in small steps in such a way that a feed mark (track of the cutting tool on the workpiece) is inverted each time the workpiece makes a round, by which the chip is varied in width and cut at a track crossing portion during the machining. Thus, chips are broken into short pieces so that the cutting efficiency and the cutting quality are improved and that the chip disposal is facilitated. Moreover, a safe turning process can be achieved.