Abstract: An elongate eccentric shaft formed from a cylindrical billet has cylindrical bearing sections at its opposite ends, a cylindrical center section, and cylindrical coupling sections outboard of and eccentric to the center section. The cylindrical sections are of uniform diameter, the bearing and center sections have coincident longitudinal axes, and the longitudinal axes of the coupling sections are coincident with one another and offset from the axes of the other sections. Adjacent each coupling section is an elliptical section having a major axis the length of which is no greater than the diameter of the cylindrical sections and a minor axis the length of which is less than that of the major axis by an amount corresponding to one-half the offset of the aforementioned longitudinal axes.