When we last left this project, I had just completed soldering the coils for our Permanent Magnet Generator together in star configuration. As you can probably imagine, things started to get a little “springy” when trying to fit everything into the mold. When I’d get one coil exactly in its place relative to the magnets proposed rotational path, it would cause another one to move or pop-up. So I broke out the good ol’ duct tape and started anchoring each one in the correct position.

With each coil held securely in its place, the next order of business was to cut 9 pieces of the fiberglass cloth about 1.5″ x 2″ and lay them between the coils. A liberal application of cyanoacrylate (CA) adhesive  – available in good quantities at any decent hobby shop – hardens the cloth sufficiently enough to create a bridge that will hold each coil to its neighbor, creating a more solid ring with each coil where it belongs.

In the photo above, you can see the strips that have been cemented are clear, while there are a few (on the lower right) that still need to be done.  I used enough glue so that not only will the fiberglass cloth harden, but that it will also run down through the winding legs around the individual wires. The trick is not to use so much that you make the coil stick to the bottom of the mold. (Guess how I know. :) )

Here it is all glued together & the duct tape removed

Before pouring any resin, I know I’ll also want to reinforce the backing and the face of the stator with some cloth inside the ‘glass. I’ll need to cut two 15″ diameter rings of cloth, each with a 6″ hole in the center.  If you lay it out and fold it right, you can minimize your cutting and cut both at the same time. It’s just like cutting paper snowflakes when you were a kid :) !

The plan will be to clamp a top onto the mold while it cures, but I don’t have a C-clamp that’ll reach the center of the mold. I’m sure there’s many other ways to do this (you could use a brick if you wanted to), but I’m going to use a threaded stud.

What?! You’ve never heard of threading wood before? What do you think wood screws are made of?

With everything just about ready, all that’s really left to do before “the big pour” is to coat the mold with an appropriate “mold release agent” so the fiberglass resin won’t bond to the wooden mold. You can see I’ve chosen Turtle Wax, but any type of wax will do. Grease will even work just fine, but you might have to spend more time on clean-up.

Since its almost 70⁰F here today, the resin’s probably only got about a 20 minute pot life. It’s not that you have to rush, but you want to try to get everything as set-up as you can so that once you mix the resin with the hardener (and the pigment) you don’t have to stop. The following pictures, therefore, are what they are; since they were taken on the McFly.

I poured about a pint (I could go for a pint or two.) into the mold and placed in the first cloth reinforcement ring. After working out a few aire bubbles, I put the coil ring in.

Pour in some more resin. Add the second layer of cloth. Work out more bubbles. Pour in more resin. Take a quick picture for the Internet…

Put on the lid and squish it all down.

Let it all harden and then remove it from the mold:

There’s a couple of chips in the outer edges – most probably from insufficient wax in the corners of the mold – but nothing even close to structural. I’ll just have to be more diligent on the next one. ;)

Overall, I’m pleased with it. It should serve its purpose well.

It’s a good day to be going green.

Happy St. Patrick’s Day!

Tags: Wind Turbine

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