Abstract: Workpieces having three-dimensional surfaces can be efficiently sanded by rotatable sanding members mounted on spindles which are supported for movement in a circle of revolution over the surfaces of the workpieces as the individual spindles are selectively rotated about their longitudinal axes in either of two opposite directions during predetermined portions of each circle of revolution. A sanding apparatus for accomplishing this function includes a cone clutch arrangement for selectively reversing the direction of rotation in accordance with a cam directed control arrangement acting on pivotally supported yokes carrying the individual spindles.

Abstract: A rotating grinding or polishing device includes a number of grinding or polishing discs formed of two or more layers of segments radiating from a central retaining area having an edge which defines a central hole. In the central area, the segments are kept together by a heat-activatable string which also maintains the grinding or polishing disc in the form of a ring, whereby the disc has the required optimum stiffness/flexibility for obtaining an effective grinding or polishing finish so that even complex surfaces can be effectively ground or polished.

Abstract: Workpieces having three-dimensional surfaces can be efficiently sanded by rotatable sanding members mounted on spindles which are supported for movement in a circle of revolution over the surfaces of the workpieces as the individual spindles are selectively rotated about their longitudinal axes in either of two opposite directions during predetermined portions of each circle of revolution. A sanding apparatus for accomplishing this function includes a cone clutch arrangement for selectively reversing the direction of rotation in accordance with a cam directed control arrangement acting on pivotally supported yokes carrying the individual spindles.