The basic idea was to build a transparent 3 phase alternator with as few metal parts as possible. The only metal parts in the design are the magnets, a few fasteners, a shaft and bearings. With no metal casing outside the windings or a metal armature the flux density will be much lower than it could otherwise be, but I wanted to try it anyway. Below is the CAD model I came up with.
The parts in the CAD model will be exported as dxf files that I can generate toolpaths from to cut out on my CNC router.
Finite Element Analysis
I arrived at the particular magnet spacing used by trying different positions in a Finite element analysis package (FEMM). You can find the software I used here www.femm.info
With the magnet positions finalized and the CAD model finished I could move on to cutting out the parts. The fisrt job was to create toolpaths for all the parts. I used CamBam to generate the paths, saved them on a USB drive and took them over to the CNC out in the garage.
First part off the CNC
I'd never cut Polycarbonate on the CNC before, but it went pretty well. Shallow depth of cut and keep the cutter moving pretty fast to avoid the material melting on the cutter.
After cutting out all the parts it was time to assemble the armature.
Nice! Everything fitted just as it was supposed to, on with the assembly...