Smaller Homemade Permanent Magnet Alternators?

[gotwind2]

In reference to this article,It is Hugh Piggotts Volvo Brake Disc PM alternator.

http://www.otherpower.com/otherpower_wind_alternators.html

Has anyone attempted a smaller version e.g 100w max output, for maybe a 4ft 3 blader prop. It would still be worth doing in my opinion, good low-rpm performance and high efficiency.

Bicycle wheel front hubs are strong and would tolerate the thrust loads (some even have integral drum brakes - maybe for high winds?).I am thinking a bolted on steel disc holding the Neo magnets. The only downside I can forsee is having to wind tiny coils - not sure about that side of things, just in the ideas stage at the moment, but I am sure it would be of great interest to others on this board.

Any help or thoughts welcomed.

Thanks

gotwind

[Flux]

Hugh has plans for a very effective 4 ft, 3 blade machine using a single rotor pm alternator.

I would not use the steel laminate approach for any small machine, you really can't justify the iron loss unless you are in a high wind area.

You can do it as a dual rotor design with smaller magnets, but unless you find a competitive source of other magnets it may work out cheaper to use the 8 magnets and single rotor as Hugh did.

I don't share your enthusiasm for your bicycle bits, but that is a personal preference. I don't think the spindle is strong enough when supported at one end and it would be a messy thing to support both ends.

Don't be too put off by my preferences, I would rather machine up a hub than spend time trying to find something suitable. If you have to find something, then I think a small trailer ( boat trolley) hub would be a good choice.

If you use this approach then use decent size discs. Messing about with little discs and coils is a sure way to get a poor result.

For small machines the air gap alternator is by far the best method.

Flux

[ghurd]

I agree with Flux on the strength issues. Maybe fine for a 20" box fan blade but 4' is getting big.

I have been really trying to get something like this together, but smaller, with common parts. Looks and sounds easy enough!

Speaker plates as magnet disks. Straight and true. The rear plate needs very little work to be used.

Winding small coils is a big job for me; they just don't fit when I am done.

Bike bearing parts are very, very hard. Even the ones from crappy bikes. I ruined a lot of high quality tools with nothing finished.

Here, in the US, bike bearings are threaded 3/8-26? (not common). Never found a tap or die.  Time permitting, I intend to make my own tap from an axle (it can't work out any worse than it has so far!).

And I never found metric all-thread to match the metric bike stuff, and won't "Request a Quote" for an 10" piece.  Maybe the next time I'm in Canada...

It is a LOT easier, and cheaper, to do a small conversion.  But then the iron losses come into play.

G-

[gotwind2]

Thanks for the comments guys - very imformative.

I've seen Hughs plans, P.D.F downloadable here http://www.scoraigwind.com/download/index.htm

Yes bike wheel hubs are super tough, case hardened. How about the bottom bracket bearing assembly, stronger and with tubular metal work to weld bits to?

I am attempting this as a real 'no machine tools' approach - to appeal not only to me but to a hole host of diy'ers.

[fungus]

I would definitely recommend that you buy one of hugh's books. They are much more up to date than the downloadable ones and the axial flux plans have a 4 foot design. Even if you dont go with his designs it has a lot of infromation that is helpful. I would recommend "wind power workshop" and his axial flux plans.

[ghurd]

"'no machine tools' approach".

Me too, except a drill.

Not too long ago, someone, the professor?, spoke about a 16' using the headset bearings, for 2 years without problems. IIRC. Maybe your search will be better than mine.

I checked a few pedal / handlebar bearings. I never thought of a cheap and easy way to use them due to the large center areas.  A couple bends and bolts in the right places would make a nice platform without any welding.

Norm has done some nice work with bike parts. But not 4' kind of stuff.

Norm needs to make a Diary with just a few photos of some of his stuff. (hint hint)

He seems to be able to make the craziest things work in an easy and simple manner.

Many people would find it interesting.

[Flux]

Yes,the book gives details of a first class neo design. The free download is for a ferrite design that may suit your low cost approach, but it would need changing to suit 4 ft blades.

flux

[zubbly]

hello gotwind2,

if its a small machine you are after and something in the 4-5 foot blade, i would really consider buying on ebay a 1/3-1/2 hp PM DC motor.  often they are dirt cheap and will give you i think the best bang for the buck.

look for Baldor, Leeson, Magnetek (the good industrial models)

all you got to do is make your mount and prop.

just a suggestion,

zubbly

[gotwind2]

Thanks Zubbly, great advise as always.

I wanted to go down the DIY route this time - basically to provide the option of making ,from scratch a 100w PMG from scrap, with minimal workshop tools i.e drill,hacksaws and metal files.

I know Compromises like this restrict options - But offer mass appeal.

A real challenge

Thankyou

Gotwind