Thinking about your cooling by "design". In order for a fan to draw air through the generator it will need large entrance holes. What will your entrance holes do about the rain, dust and ice formation? Cranking out 2kw and soaking wet coils may not be a real good idea. Although it may be impressive for a second watching the smoke. You say you like using JB weld, but do you realize JB weld crawls up the magnet when applied? Im not sure a void under the magnet will keep JB weld in place without it crawling around and opening that void back up. I dont know, Ive never wanted to attempt it. Lastly, you may want to rethink your 5 thousandths air gap. Not only vibration of the coils causing a rub but even gluing the mags on I doubt will keep your rotor within 5 thousandths of an inch. Ive always been told to keep the air gap at half the magnets thickness or slightly less. Amazing how similar a garbage disposal stator looks compared to your home made.
This comment ended up in the wrong thread so I tried my copy and paste skills to see if I could move it here.
The coils are going to be sealed with air-dry electric motor varnish when I get the stator done to fill voids in the winding and prevent coil vibration. I'm pretty good friends with a local fellow here who has an electric motor shop and he said he'll varnish it for me just like they do electric motors. Initial testing will be done, however, without varnish in case I have to unwind it and rewind it in case I don't get it right the first time.
Alternators on tractors and offroad equipment run in much more severe duty conditions than a wind turbine, with dust, water, dirt, etc.. with open coils and fan cooling with not a single problem. A lot of this equipment gets pressure washed to clean it up with the pressure washer blowing water directly into an open alternator with slip rings - and they still work without a hitch. This one will too.
Secondly, the air gap is not adjustable in this type of generator so there's little room for error in winding.
I have run the magnet to stator gap at the thickness of a piece of paper on axials with JB Welded magnets in the past with not a single problem pushing 1.5 kW. It does not rely simply on the JB Weld. The magnets are also pinned. The mags come with 1/8" holes and I use 1/8" split pins. They have to pressed in place over the pins because it's an interference fit. The force to remove the magnet from the pin is greater than what the magnet has for attraction force to the steel rotor. To do the initial fit of the rotor to the stator I made "dummy mags" out of 1" x .5" bar stock. The other day when I was doing some figuring on forces and what I need to hold those mags on there I spun my rotor in the lathe at 600 rpm with the dummy mags on - no magnet attraction, no glue - just the pins holding them. They didn't even attempt to move at 600 rpm with just the split pins holding them in place. The JB Weld is secondary.
I'm starting out with a .005" air gap between the magnet face and stator core until I find out how much flux I'm going to get thru the coil legs with N42 magnets. That will be done by winding a test coil with the number of turns based on my experience building dual rotor axials, based on a .750" air gap. When I find out how close this thing comes to that benchmark, then I will adjust the final air gap by removing the core, unwinding the test coil, and machining the inside of the core, if necessary, to increase it. I have no problem machining and building things to +/- .0015" tolerances - I do it all the time. It's easy to add air gap if the initial tests show it can be increased. It's not so easy to decrease it if it's built too wide to begin with. If I end up with a .050" air gap in the end, that's even better.
If anybody else has ever built one of these from scratch then I'd have something to go by. But all I've seen is crude stuff like sticking coils inside brake drums and such, and certainly nothing with an internal rotor with a homemade powdered iron core that I've ever seen in the homebuilt stuff. So there's a lot of unkowns and I prefer to build a cushion into it for initial testing to cover the unknowns.
It seems there's a lot of people interested in this generator design, based on the emails I've gotten on it. Like one fellow said, he's glad I'm going thru the "labor pains" to build it because then other people have something to go by if they want to attempt it. Until then I'm breaking new ground, and when you break new ground you never plow it too deep the first time over.
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Chris