Sinking the magnets into drilled holes will loose you most of the flux.
I've been considering doing a conversion by:
- Drilling and flat-bottoming a hole for each magnet, then,
- Drilling out a clearance around the magnet hole, large compared to the gap, almost touching the adjacent magnet holes, and
- Maybe grinding away the remaining honeycomb structure among the magnets in each pole area.
That way each magnet would sit in a slight recess with just enough shoulder to hold it in place, but very little shorting of the field.
Maybe also I'd just do, say, the north poles (with double-deep magnets) and let the rotor remain full-sized to form "consequent" south poles.
This would have these advantages:
- It could all be done with a drill press (and maybe a dremmel hand grinder) though you'd need flat-faced mill-style bits for the final cuts.
- Enough of the rotor's original structure would be intact so it wouldn't come apart into a stack of laminations.
Seems to me that, even if you grind the rotor down or replace it with a new, smaller one, drilling a shallow flat-bottomed hole for each magnet to leave a short (much less than half the magnet's depth) shoulder around it, should avoid wasting any significant fraction of its field.
What do you guys think of that approach?
