Magnetic disc drive device with hub and clamper assembly for reducing post-assembly machining

Claim 1

A magnetic disc drive device comprising: a cylindrical hub which rotates with a plurality of magnetic discs, the cylindrical hub having disc clamp holes defined in an end surface thereof and a flange on which said magnetic discs are positioned; a motor for rotating said cylindrical hub; at least one spacer, disposed between said magnetic discs, for separating said magnetic discs from each other; a projecting member, formed between the disc clamp holes and the magnetic discs to be clamped, extending in the axial direction of the hub on an outer edge of said end surface of the hub, an upper surface of said projecting member being the only portion of the end surface of the hub that is machined during post-assembly machining; and a clamper clamped on said upper surface of said projecting member, said clamper exerting clamping force on said plurality of magnetic discs wherein the projecting member has a mounting reference surface for said clamper clamping the magnetic discs, said clamper contacting said mounting reference surface when said plurality of magnetic discs are clamped.