Method of making a molded commutator

That improvement in the method of producing electric motor commutators which comprises forming a tube with a plurality of internal longitudinal teeth having rectangular profiles, passing longitudinally through said tube a mandrel formed with external teeth having profiles changing progressively along the length of the mandrel from pointed at the leading end to rounded at the trailing end to progressively displace metal from the centers of the teeth to the opposite sides thereof to change the rectangular profile of said internal teeth to a profile which is substantially T-shaped in cross-section, locating a bushing of smaller diameter than said tube concentrically within the latter, filling the annular space between said bushing and said tube with plastic molding material to form a hub with said T-shaped teeth embedded and anchored in said material, and slotting said tube longitudinally between said T-shaped teeth to form individual commutator bars.