Abstract: The method disclosed herein briefly includes the steps of (1) forming a pair of nestled cup-like pulley hubs having radially extending flanges in side-by-side relationship and (2) rotating the nestled hubs about a rotating axis while simultaneously urging a tapered projection on the inner surface of a rotatable, annular forming tool between the side-by-side flanges to spread the flanges and form a V groove with only minor relative rotary motion between the flanges and forming tool in their areas of contact. By having the working portion of the forming tool formed on the inner portion of a rotatable, annular tool, relative rotary movement between the flanges and tool and hence galling of the flanges is kept at a minimum. The tool disclosed herein is an annular groove forming tool having the working portion thereof formed on the inner surface of the tool, the tool including the means for mounting on the same on a spinning lathe so that the tool can be used while the pulley is rotated on the lathe spindle.