Rotary file, support member and abrasive device

Claim 1

An abrasive rotary disc assembly arranged to be rotated about a central rotational axis and comprising: a ferromagnetic abrasive disc having an outer surface including cutting elements thereon, said outer surface being centrally planar and having a convexly curved radially outer periphery, said periphery including at least a portion of said cutting elements thereon, and an inner surface extending substantially parallel to said outer surface at least at said periphery, said inner surface including circumferentially spaced, axially projecting disc stop elements disposed between the center of the disc and said curved periphery; a support member for said disc having an outer surface corresponding geometrically to said inner surface, including a convexly curved radially outer periphery corresponding in shape to said disc inner surface at the disc periphery, said support member including curcumferentially spaced stop engaging means for cooperating with said disc stop elements to prevent relative rotation between said disc and said support member, and magnetic elements arranged to attract said inner surface of said ferromagnetic disc to the outer surface of the support member; said disc inner surface engaging said support member outer surface in contiguous relationship with said disc inner surface at the disc periphery contiguous with the convexly curved periphery of the support member, with said disc stop elements engaging said support stop means and said magnetic elements solely retaining said disc axially against said support member; said disc stop elements and said support stop means comprising cooperating radially extending grooves and projections, with at least the radially outer ends of the grooves and projections disposed closer to the disc periphery than the disc center.