The magnets that I purchased have a 3/16" hole in the middle of them. I planned on using this hole to 'pin' the magnets onto the rotor. Again this step might possibly be unnecessary, but doing it will allow me to use less resin around the magnets. There is almost no way that the magnets can now 'exit' the rotor despite just about any reasonable speed that the turbine might be able to turn at.

In addition it should make mounting the magnets easier as no placement template is required, nor any super-glue to temporarily hold them on until they are completed with the addition of resin. I have to believe that this is the ultimate in strength, and the more exposed area should help in circulating more air through the stator, and keeping everything cooler.

I started out by marking out the center locations of each of the 16 magnets on each of the rotors and drilled them out as a 'pair' By pairing the plates and drilling them out simultaneously I will ensure that the magnet locations match between the plates. I also marked an alignment mark on each of the rotors so that later they could be matched up

Each of the 3/16" holes were then drilled out.

I cut 32 lengths of 3/16" steel rod out just about 1-1/8" long. These pins were then inserted into the rotors, spaced so that they extend out the other side of the plate by just under 3/4" and then I TIG welded each pin into place, ensuring that they will not move.

Here is a picture of the rotor plates with pins and awaiting positioning of the magnets:

Then I did was to drill and tap 4 holes for the jack screws in the most forward rotor plate, I made them for 1/2"-13 NC thread. I then completely cleaned them up using some acetone to remove any oil from the surface. I used a felt pen and drew some lines from magnet pins to the corresponding one on the other side, this will help me to get them straight. I also used the felt pen and marked on each rotor the pole for each magnet location.

I drilled and tapped 4 holes for the jack screws in the most forward rotor plate, I made them for 1/2"-13 NC thread. I then completely cleaned them up using some acetone to remove any oil from the surface. I used a felt pen and drew some lines from magnet pins to the corresponding one on the other side, this will help me to get them straight. I also used the felt pen and marked on each rotor the pole for each magnet location.

I decided that I needed to make up two wood wedges that the combined thickness is 3/4". I will be using these wedges to position the magnets over the pin and to lower them down to the plate surface. It worked out fantastically!

I got one magnet out and hung it from a string to determine which face was the North pole, I then wrapped it in some tape and clearly marked it, I used this as my reference magnet.

For the first rotor I decided to pre-sort the magnets and mark them for polarity. I got one magnet out and hung it from a string to determine which face was the North pole, I then wrapped it in some tape and clearly marked it, I used this as my reference magnet. I put a long piece of angle iron out, separated and marked 1/2 the magnets. This turned out to be a not so good idea and for the second rotor simply 'peeled' off the magnet, determined the polarity and placed it into position on the rotor.

The amount of force from these magnets is amazing! To separate them out of the stack at times was like a sumo wrestling match, and it took about all my strength to separate them. What worked easiest was to take the magnet and rotate it 90 degrees, then turn it lengthwise so that there was not so much surface area to deal with

Here are a couple of pictures showing the wedges in place, the magnet put into place to engage the pin and finally the wedges pulled out:

And finally the rotor with all the magnets in place:

Before I put on the last magnet that I had been using as my reference magnet, I used it and went around to all the magnets on both the rotors to double check and ensure that I had indeed marked and placed them correctly. Once done I mounted the last magnet. I then checked that the alignment of all the magnets were correct and then went around all the edges of the magnets with some super-glue to keep them from moving.

Finally I made up two 9" diameter 'islands' out of 3/4" thick plywood. Once I rough cut them out with the jig saw I put them onto my lathe and brought them down to the exact size desired, I also was very careful to make the outside diameter slightly angled for relief to ease in removing them (I had this problem casting the rotor).

With the wood islands caulked and positioned correctly I started chopping up some fiberglass matt into fibers to help give the resin some strength. I first made up 10 oz of straight resin and wetted out the entire interior area and all along each of the sides of the magnets. The next two 10oz cups of resin I put in the chopped fibers, with the final two 10oz cups of resin I again used it straight so that it would level out nicely. So in all I used about 50oz of resin total for both of the rotors.

Here is a picture of the resin poured also notice that I put tape on the magnet surfaces and around the perimeter:

So in all each coil used about 1.58 lbs of copper, and very little remained on the spools. To wire up the coils I ended up unwinding the last coil and cutting it, so each coil ended up being about 79 turns. So in all - almost 20 lbs of copper were used to make up the coils!

Post Note: I made mistake, the coils should be wound with 59 turns of #14 wire, 2-in-hand!

Finished up the stator mold. My approach has been a bit different than others in that I wanted to reduce as much as possible the amount of resin that went into a stator mold, in addition I wanted as much cooling around the coils as possible.

As much as I could look locally I could not find any 3/8" diameter bronze bolts, the largest I could find was 1/4". I wanted to put in the power studs into the stator when we cast it, but this will have to wait until afterwards.

Here is a picture of all of the coils sitting in the mold with some strips of fiberglass cloth super-glued to hold them together:

You can see the 1/4" thick plywood 'rose' which I cut out to basically match the outside of the coils (plus about 1/4"). All internal edges were filleted with some caulk to produce a radius - essential to help remove the finished stator from the mold.

The overall diameter is 22", and at each of the black lines will be a hole put in to hold the stator in place on the turbine. The mounting holes are fairly close to the coils, but have some clearance. I also made a side 'island' where the power connections will be made.

The central portion of the mold is 3/4" thick and around the outside edge I used some 1/4" plywood (on both top and bottom) to reduce the outside edge to about 1/4". Also I added blocks into the center of all of the coils that will 'open' up the centers to allow cooling air to circulate.

Each of the center coil blocks were lightly glued and then screwed from the back side to hold them in place. In addition I did the same for an 8" center island. My thoughts were that if the stator was difficult to remove from the mold then the center island could be removed and all of the coil center blocks could come out with the stator. Worst case is that I could remove the center islands from the extracted stator outside of the mold.

I wired up the coils in a 'star' fashion and brought the whole assembly over to my good friend Paul Schreiner, of PS Composites. Paul helped me out with finishing the mold, using some wax strips around all of the center islands, applying a coat of mold release and then a couple of coats of PVA which helps have the final product release from the mold.

Paul had just enough quantity of a special high-temperature epoxy that I wanted to use for the stator. I had seen enough references to burnt up stators to take this additional precaution. In addition milled fiberglass fibers and micro-ballons were used to thicken up the resin and give it more volume.

We then used a lot of strips of 10oz cloth cut into 2" wide strips and laid them into the voids, used about 3 quarts of the epoxy and clamped up the mold. All of the cloth was 'wetted' out and removed as many air bubbles as possible. Since we were compressing the whole assembly at least four layers of cloth were put around all surfaces as well as top and bottom of the mold, with even extra around the outside 'rose' area (probably up to 10 layers). This is a lot more than I have seen from others making up stators, but it should be an extremely strong and durable unit once done.

When we clamped up the mold we got some epoxy squeeze-out from about 90% of the edges so we are hoping that enough epoxy was inserted into the mold, if not it can be patched up afterwards.

The top of the mold consisted of one 3/4" thick plywood (with matching 1/4" plywood 'rose') as well as the 3/4" thick section of the mold that was removed when I routed out the main body of the mold

We used quite a few clamps to pull the top of the mold down onto the stator as well as a 1/2" bolt into the center, all of these were necessary to compress the 'expanded' coils back down to a reasonable thickness:

It was a good thing that I had planned for contingencies as it was necessary to remove the 8" center island, and all of the coil center blocks as well. It was not a pretty site as I ended up drilling holes in the bottom of the mold and using a 1/2" steel rod and hammer to remove them...

The culprit appeared to be that I did not build in enough of a relief angle around the mold center and all of the coil blocks. The wax and PVA that Paul put onto the mold worked fine and it would have released easily had I built the mold with some more effort and forethought, but time was working against me when I made the mold.

To make a long story short, I got out the stator in a single piece, however the mold was not as lucky. I have a bunch of cleanup to do around all of the edges but here is how it looks so far:

The epoxy is rock hard and there are very few areas that have a bubble caused by lack of resin, but I am quite happy with the results.

I cleaned up the resin edges around the rotors and spray painted them black. Here is the outside rotor with the four jacking screws installed and awaiting assembly, you can clearly see the pins in the center of each magnet:

Assembly started with the alternator finally, got the center hub, with the attached brake rotor in place first using some 12" lengths of stainless steel all-thread. Important note: all nuts use lock-tite as well as lock washers! For the stator I used 8" lengths of all thread. Here is next picture with the back rotor mounted as well as the stator. In the center you can see the aluminum spacer that I made up to space the rotors.

I had a little trouble finding exactly the amount of aluminum that I needed to space the rotors apart and ended up using some stainless nuts and steel washers to establish the final distance the rotors were apart.

Outside rotor installed:

I could have made the spacing between the rotors and stator pretty tight, but opted out for about .100". This will give me slightly less output but hopefully less maintenance issues. Here is another picture with the outside rotor installed as well as the final spacer between the rotor and the blade hub:

Once I got to this point I decided to do some quick output tests. Not very scientific but spinning the rotor by hand I was able to measure about 50volts between each of the 3-phase posts, no load. Don't know if this is good or not as a very rough test I checked across each of the posts I measured the same, so output across each phase looks roughly the same. At least this tells me that I think that the coils are connected correctly in each phase and that the magnets have proper alignment/polarity.

Post Note: In testing your stator you want to be sure that the desired voltage output between any to phases reaches the desired amount when the rotors are turned at the desired cut-in speed. If it obtains the desired voltage at a slower rpm it could stall, too high and in high winds it may turn too fast! The easiest (and surest) way is to connect the turbine it to your rectifier(s) and measure the DC output. In my case (48v nominal system) I want 54vdc at approximately 80rpm.

Finally got around to some last minute modifications to the mounting of the linear actuator as well as making up the connecting linkage between it and the brake caliper. The linkage had to be made so that it could be taken apart in case of maintenance. Here are a couple of it (first is a little fuzzy):

Alternator is assembled and ready to put into service.