US Patent 11953080 Shaft with surface finished ridges

A ball screw spline actuator includes a shaft, a ball nut, and a ball spline. The shaft includes a helical groove and a spline groove intersecting the helical groove forming intersections having a least one ridge including a first surface finish formed by a first manufacturing operation. The ridge is subsequently reformed through a second manufacturing operation to include a second surface finish to reduce stress concentrations in the ridge from cyclical loading from at least one of the ball nut or the ball spline. In one example, the second manufacturing operation reforms the ridge to include a surface finished edge.