Commutator for electric rotary machine and manufacturing method thereof

A commutator mounted on a rotor of an electric rotary machine, the commutator comprising:

• 2n commutator segments, it being an integer;
• 2n segment bases formed by separating a metallic base plat, each segment base contacting each commutator segment, the 2n segment bases being insulated from one another by slits formed on the metallic base plate wherein:
• the 2n commutator segments are electrically insulated from one another;
• the 2n commutator segments form n pairs of commutator segments, the commutator segments in each pair being positioned symmetrically with respect to an axis of the rotor;
• and
• the commutator segments in each pair are electrically connected to each other through a connecting portion formed integrally with the metallic base plate, wherein n pieces of the connecting portions are formed integrally with the metallic base plate, and the n pieces of the connecting portions are all depressed from a metallic base plate surface contacting the commutator segments by a distance exceeding a thickness of the metallic base plate.