When the supply brushes are placed on the commutator at angle of 60 degrees from each other (using the center of the shaft as the midpoint) a supply of 14.15V was applied and the voltdrops across the bars was 219mV. When the angle between supply brushes was reduces to 30 degrees the potential measured on the supply probes droped to 10.71V, note: the welding machine supply was not adjusted, only the distance betw the supply probes on the commutator was changed.
The volt drop from bar to bar was then measured to be 356mV.