Thanks i understand the need for iron cores and stator housing to make an efficient generator. Im not worried about efficency at all i just want it to look nice and make a few volts from a little steam engine. I mentiond it will be more like the diy wind generator type that use no iron at all if possible. If its usless then il add iron coil cores then iron rotor and and so on untill i get somthing workingNext to copper, aluminum is about the worst stuff that you can use for efficiency. Just consider that magnetic brakes are, essentially, magnets held up to a good conductor that's moving. Back irons behind the magnets and the coils will significantly increase efficiency, and far more so if you use laminations that are electrically isolated from one another (the traditional thing to do is use varnish -- just about any paint-like material will work).
Personally, if I could find a sheet of magnet iron and I had a laser printer (or a friend with one) I'd cut out a stack of laminations from that, varnish them, and stack them.
Alternately, I've always wanted to try getting hunks of ferrite, and having them laser- or water-cut to shape.
If you don't want to mess with back iron, consider making the whole thing out of bakelite, or some other non-conductive material.
Il have to find a link to a thread on here to explain what im aiming for. Again if the alloy housing causes that much loss il cast it in iron also.
First thing i need to do is make the coils and figure out the wiring setup that is the biggest task in my view the rest is all casting and maching the fun bit.