Jim, consensus seems to be that you dont want both legs (sides) of the coil over the same mag at the same time, cause they will cancel. if you try to cram alot of small coils in there, you will get just that, and be wasting alot of the wire.
now, that said, because the coil legs have width, it is not actually possible to make the coil the optimum size, most folks seem to shoot for the average lap of the coil to be the same size as the mag, others like the hole in the coil that size.
the coil size is also related to the spacing to the next mag. try to get the average lap to hit the next mag, just as it's back leg is leaving. this implies that there is a relationship between the spacing of the mags and the mag size as well.
but, when you have the option, multi-phase machines will work better. that also changes the relationship, but generally in an easier way, by making less coils, which helps with the fact that they have a finite thickness.
i think danb puts his mags a bit closer, to try and get more flux in the space.
i agree with others who have said to get a second ring of mags inside the first, or switch to bar mags on the lower rotor, and move the second ring of rounds to the top.
be very careful with the truing on these rotors if they get very large, they will tend to become floppy with all the mag pulling on the edge. some strengthening ribs welded to the back maybe?
allan
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