| 摘要 |
PROBLEM TO BE SOLVED: To suppress such wobbling of a disk-placing surface as originating in machining resistance and to prevent the wobbling from further deterioration due to environmental conditions or aging by sticking a resin film on the surface for placing a disk recording medium on a metallic hub base and cutting the upper face of the resin film so as to make it vertical to the rotary axis. SOLUTION: A hub base 3 is a disk-shaped member formed by machining using a brass material, and is provided with a through-hole in the center. A shaft 1 is fitted to the through-hole of the hub base 3 and fixed downward. A concentric resin film 4a with a through-hole in the center is glued on the upper face of the hub base 3 by means of an adhesive; the upper face of the resin film 4a is machined to form a plane vertical to the rotary axis of the shaft 1 and to make it a disk-placing face on which a disk recording medium is placed. The resin film 4a has a smaller machining resistance compared with metallic materials; therefore, the disk-placing face can be formed with higher precision.
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