Abstract: A workpiece positioning table includes a generally channel-shaped base member having a bottom web element and a pair of laterally spaced side wall elements projecting upwardly therefrom. At least one of the side wall elements is pre-tensioned so as to possess a spring force tending to deflect such side wall element inwardly towards the other of the side wall elements. A V-shaped notch is formed in the inner face of each side wall at a location above the bottom web element and in vertical alignment with each other. Each such notch extends lengthwise of the side wall, desirably to be coextensive therewith, and is heat-treated to a hardness greater than that of the adjacent surfaces of the side wall. The positioning table includes a carriage member carried by the base for reciprocatory movement between the side walls thereof.