Collet chuck for splined workpieces

In combination, a chuck and a workpiece having a base diameter surface interrupted at regularly circumferentially spaced intervals by axially extending, radially projecting splines having radially facing surfaces, said chuck having a body, at least two collets supported on said body, each collet having a plurality of regularly circumferentially spaced fingers which extend axially forwardly on the chuck body and are radially resilient at their forward ends, each of said fingers having radially facing work-engaging surfaces at their forward ends, the fingers of the collets being interdigitally disposed circumferentially at their forward ends around a common circle so that the circumferentially adjacent work-engaging surfaces are associated with different collets, the circumferentially adjacent work-engaging surfaces being spaced apart circumferentially a distance at least slightly greater than the circumferential extent of the radially facing surface of each spline on the workpiece and the number of collets being related to the number of splines on the workpiece so that, when a workpiece is telescopically engaged with the collet fingers, the work-engaging surfaces of at most one of the collets will register radially with the radially facing surfaces of the splines and operating means for shifting each of the collets to the work-engaging and work-releasing positions, said means being operative to shift one collet to the work-releasing position in the event that the work-engaging surfaces thereof are not displaced radially a distance sufficient to engage the base diameter surface of the splined workpiece when the collet is shifted to the work-engaging position.