The portion of the armature that carries the voltage through the windings. The comm is usually divided into 2-6 sections made of copper and surrounds the rotor. This will need to be cut on a lathe every few runs to keep your motor in tip-top shape. If your running a modified motor, you should cut your comm every 4-6 runs. If your running a stock (27T) motor, you should cut it every 8-12 runs. If your a basher, you can slack off a little, but don't neglect your motor. Otherwise you might end up throwing a $60 motor in the trash. Also known as the comm.