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Wind Turbine Diary
6th May
Getting the magnet rotor out of the mould was a totally different story this time! It came out with almost no fight, thanks to using a ridiculous amount of wax polish on the mould, as well as releasing spray. So the mould is in good shape to be used again, which is just as well, since i don't have any plywood left to make another one. There was a little rim around the outside where the resin was held in by the silicon gel. Next time, i'll leave the gel to go harder before expecting it to perform a task such as this... In this picture, i'm halfway through hacksawing the rim off to make a nice clean disk of steel and plastic: (notice how the mould is nice and clean!).
Dave Stewart arrived to see what all the noise was, and proceeded to find the tap necessary for the threading of the holes in the other magnet disc. So he showed me how to do it, first of all:
Then i tapped out the other two holes using this device, with a bit of metal cutting liquid (orange bottle) on it:
The point in putting threads in these 3 holes (while the four other holes remain untapped) is that the threaded holes will be used to "lower" the magnet plates into their final position, where they face each other over a thin gap of air and stator. The magnets will be arranged so that opposite poles will be physically opposite each other, so the plates will be very strongly attracted to each other. If threaded rods (like long bolts with no head, as seen in the picture below) aren't used to slowly screw the top plate into place, then they will just snap together and ruin the stator in between. The following picture shows the back rotor bolted on to the hub on which it will spin, using threaded rods. When the turbine is assembled, these rods and two others will travel from where they are through the middle of the stator, then through the equivalent 4 holes on the back magnet plate, then through the blade assembly on the front. This is why the rods need to be quite long, although not quite as long as they are in this picture. You will see in future pages...!
Tomorrow the blades need to get their third coat, and i want to try and get the other magnet rotor cast... big plans.
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