David Y Mak, 4714794 Ruthelen Ct, San Leandro, CA 94578

4587647, May 6, 1986

Feb 28, 1983

6/470108

David W. Mak - San Jose CA
Terry L. Branson - Cupertino CA

Xerox Corporation - Stamford CT

G11B 1702

369270

The spindle for a disk drive comprises a dish-like hub for centering a removable disk-like recording media and a magnet chuck for clamping the recording media against an axial position reference surface on the hub. To stabily center the recording media on the spindle to provide a reference surface for controlling the axial positioning of the media, the hub has a central conical post which extends axially of the spindle beyond the plane of a radially displaced annular rim or flange. The post narrows toward its free outer end with a fixed taper, so that the recording media seats thereon and makes interference contact therewith before reaching the plane of the rim. To clamp the disk to the hub and to seat it against the rim, there is a magnetic chuck comprising an annular magnet which is disposed between the post and rim and a strike ring which is engaged with or embedded in an inner circumferential portion of the disk for deflecting the recording media into contract with the rim. For example, if the recording media is configured as a so-called "air sandwich" for what is known as "second surface" optical recording, the strike ring is advantageously embedded in the media while the air sandwich is being assembled.