Patent ID: 7295002

Claim:
A spinstand for rotatably supporting a disk pack, said disk pack including one or more annular magnetic disks concentrically arranged in a stack along a disk pack axis (DPA), said disks being mutually spaced apart in the direction of said DPA, comprising: A. a base unit, B. a spindle coupled to said base unit and having an output drive element adjacent to a disk pack region and having an associated spindle drive motor and adapted to selective rotate said output drive element about a spindle axis, said spindle axis extending through said disk pack region, C. a vacuum chuck assembly coupled to said output drive element for removably positioning said disk pack in said disk pack region whereby said DPA is coaxial with said spin axis in response to a selectively applied vacuum, wherein said vacuum chuck assembly includes: i. a base assembly disposed along a central axis and adapted for coupling to said spindle output drive element and, a. a centering bushing having a cylindrical inner wall having a diameter D and being coaxial with and extending along said central axis and defining a base interior region, b. a vacuum port adapted to fluidically couple an applied vacuum to said base interior region, c. a lower disk support surface extending transverse to said central axis and adapted for engagement with one end of said disk pack, ii. a cap assembly disposed along a cap axis and including: a. an inverted cup-shaped element extending along a said axis and disposable opposite said base assembly with said cap axis being coaxial with said central axis, b. a piston extending from said cup-shaped element along said cap axis, said piston having a cylindrical lateral surface having a diameter less than D, and wherein said lateral surface includes a circumferential groove extending thereabout transverse to said cap axis, c. a circular seal disposed in said groove of said piston, defining a cap interior region between said seal and said cup-shaped element, and d. an upper disk support surface extending transverse to said cap axis and adapted for engagement with one end of said disk pack, wherein with a disk pack positioned on said lower disk support surface with said DPA being coaxial with said central axis, and with said cap assembly positioned opposite said base assembly with said cap axis coaxial with said central axis, a vacuum applied to said vacuum port causes said circular seal to pneumatically seal said base interior region with respect to said cap interior region whereby said vacuum causes a pressure differential across said piston thereby biasing said piston toward said base assembly, thereby compressively supporting said disk pack between said lower disk support surface and said upper disk support surface.