Reversibly rotatable chuck with internal cam for shifting work axis

A method for chucking and automatically turning a workpiece about alternate axes of rotation for processing operations, comprising the following steps:

• providing a machine having a spindle which is reversely-rotatable about a spindle axis;
• securing a chuck body to said spindle, said chuck body having a body axis of rotation coextensive with said spindle axis;
• mounting a cam unit within said body for rotation about a first cam unit axis with respect to said body, and permitting said cam unit to freely rotate, in opposite directions, within a predetermined arc, in accordance with chuck body rotation and inertial forces acting on said cam unit;
• affixing a chuck means to said cam unit for holding a workpiece with respect to a second cam unit axis, said first and second cam unit axes being parallel and spaced apart;
• providing a stop means for limiting rotary movement of said cam unit with respect to said chuck body, in reverse directions;
• rotating said spindle in a first direction and driving said chuck body, cam unit and workpiece in unison;
• processing a first workpiece diameter;
• reversely-rotating said spindle and chuck body in a second direction and effectuating lost motion between said cam unit and chuck body, thereby displacing said first workpiece diameter offset with respect to the spindle axis;
• and
• processing a second workpiece diameter, eccentric with said first workpiece diameter.

A method for chucking and automatically turning a workplace about alternate axes of rotation for processing operations, comprising the following steps:

• providing a chuck body having a body axis of rotation;
• mounting a cam unit within said body for rotation about a first cam unit axis with respect to said body, and permitting said cam unit to freely rotate, in opposite directions, within a predetermined arc, in accordance with chuck body rotation and inertial forces acting on said cam unit:
• affixing a chuck means to said cam unit for holding a workplace with respect to a second cam unit axis, said first and second cam unit axes being parallel and spaced apart;
• providing a stop means for limiting rotary movement of said cam unit with respect to said chuck body, in reverse directions;
• rotating said chuck body in a first direction and driving said chuck body, cam unit and workpiece in unison;
• reversely-rotating said spindle and chuck body in a second direction and effectuating lost motion between said cam unit and chuck body, thereby displacing said workplace offset with respect to the body axis;
• and
• processing a workplace diameter which is eccentric with one of said first and second cam unit axes.