Thanks bearing. That's a very good point. I guess the "unbalanced" rotor/pole combination would be noisy, too...bearing said:I don't think a stator with 15 teeth is going to work well. With 14 or 16 poles, windings will, as you say, be put in groups of 1/3 of the diameter. Every time a phase pair is energized it will "bend" the rotor(s) and shaft. See the summary at the bottom of this page: http://powerditto.de/15N14P.html
It might work better with an axial design with small diameter, but I would personally avoid it.