hello gotwind.
like so many of the alternators you build,
that's a very nice looking configuration you have assembled.
you have used a mag spacing that appears to be something like 3x mag width.
i don't imagine many of the flux lines being drawn so far sideways to the next mag.
using a single rotor like that i would think that a great deal of the flux will be turning around and heading directly for the steel in that rotor.
so whether it is pulled over the edge or not really doesn't matter.
a few things you might consider.
rather than black tie wraps, use a short piece of the same conductor or a finer gauge to retain the shape of the coils .
you can lay it in the coil jig before you even start to turn the coil.
and when in place it's almost invisible against the copper of the coil
i have been thinking a great deal lately about using steel /iron wire as a flux return.
it would act like laminates but present fewer problems to create.
you could lay your coils on top of it with out revealing it .
i love the use of acrylic as a stater support, beautiful.
it's practicality is directly related to the purpose of the alternator .
if you can let the volts float it shouldn't get too warm.
but if your holding it down and ramming lots of amps through ,
well, it's bound to get a bit buttery.
i know you will put this devise on some sort to pole or tower out of sight
but consider , if you created a vertical mill just as nice .
people could walk right up to it and see how beautiful.