Since the aluminum is spinning with the magnets there would be no flux change in them from the magnets. Magnetic fields generated by the current in the coils in a real alternator might have some effect, but they are on the ends of the magnets. I suspect that the screws might affect the pattern of the magnetic fields a bit, but I am not sure exactly how based upon the positions.
I would note that I can wire a couple of stepper motors together and the second will spin when the first one is spun, but they are not that efficient of generators. Still, Jerry's rotors there look pretty good to me as 4 pole rotors. I like Warrior's use of the steel outer shoe with multiple smaller magnets too. Rich'A Joule saved is a Joule made'[ Parent ]