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My small axial flux turbine

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klsmurf:
Hi All,

Waiting on parts, so I've got time to download photos and do some documenting. Don't know how much interest there will be, but here it goes.
A little background to start. I have been a member here for a couple of years and always wanted to build an axial flux turbine. Like bow-ties, wind turbines are cool! I can't justify building a 10' at this time, mainly because of tower costs.

Like many on this board, I'm a tinkerer and a recycler. I had an opportunity last fall to acquire a box of hard drives in a labor barter deal, perfect! Wire from a couple motors along with various hardware bits I had, I've got the start of a small turbine.I've read the books, practically read the whole board, but you have to have lab time. That's why we tinker!

State of the art testing facility:


My magnet rotors were 2 saw blades on each side though well aware of the problems.The blades happen to have a sixteen pole layout with good spacing.


The wire I had available in quantity was #24 and #21 AWG. I wound a test coil of each.


 Since I haven't played with magnets and coils since high school physics, I started with a few basic observations. I stacked various heights of magnets on each rotor and watched the voltage change. I also did the paper clip test on all variations. It stuck on all of them of coarse, but you could tell the strength by feel.

Up to this point, I had know idea what kind of power was possible. I took the voltage reading from the #21 wire and calculated that I could make a 3 phase, 12 coil stator that would work for a 4-5' prop. I compared my test coil to my CAD mock up and saw plenty of room to wind 2 in hand. I wound one of those coils and tested.


During this time of test, I knew there was all kinds of flux leakage. In fact, the third layer of magnets on each rotor didn't contribute much, it all seemed to leak out the back. I made a trip to the local recyclers a found some .25" plate and had some 7.5" discs cut.


More to follow.....                                         Kevin

gww:
I always love to see projects in pictures. Can't wait for more.
gww

klsmurf:
Hi All,
From the last picture I posted, you can see some hardware attached. The discs I got were just that, blank discs. Getting them to what I needed is a whole other story. I don't own a mill so I'll just say grinder, files, an antiquated drill press and a whole lot of measuring and marking.

Checking alignment:


After some cleaning, painting, and marking I got the magnets relocated to their new homes.


I could now return to coil testing. From the new data I determined that I would need 74 turns for 14 volts wired in star. That was down from 86 needed with the saw blade rotors. Quite the difference giving me lots of room. ( I'm considering winding another stator down the road with single strand #16 AWG, it would be close) For now, I'll finish out this one with what I got and hope I got enough wire.
I didn't:
http://www.fieldlines.com/index.php/topic,147767.0.html


Having sorted that, it was time for some molds and templates. My magnet and coil thickness didn't work for any common dimensional building material, so having a good choice of scrap and doing some sanding, I got things made up.



Wiring the stator was pretty straight forward. I did however take the liberty of planing for, and will, bring the star point out. I twisted, crimped, soldered and shrink wrapped the connections. They shouldn't be any problem. I know because after double checking  I found a flipped coil. Damn!



The wire I used was reclaimed so I wanted to make sure all the coils were good to go. I rigged up a test for resistance and all coils were fine. I did the phases also once everything was soldered together.



This is where I'm at present. The vinlyester should be here this coming week so I may do some pouring next weekend. Thanks for looking. I'll keep you posted.
Kevin

gww:
This is fun and you are providing lots of info.  Can't wait to see it done and hopfully working well.
gww

dave ames:

Thanks for the closer look Kevin. It's coming together very nicely. ;D

Your pics point out another possible advantage to a higher magnetic pole count in a smaller build that I may have been missing...that is the real estate gains made in the center of the stator by the larger number of smaller diameter coils..that space is at a real premium in a small diameter axial machine. Well done!

Looking forward to the next installment 8)

It's all good fun!
Cheers, dave

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