Wind Turbine Diary

13th February

So, after what seems like a long absence due to 13 consecutive days of work, today is time to get going again!  It's not as cold as it has been recently, and quite dry so with the help of my dad and Dave Stewart, we finally got the stator (the stationary part of the alternator) cast in polyester resin.  Basically that means setting the coils inside plastic and feeding the flex wires out of it.

I was a bit apprehensive about the process since I've never done anything like this before, and if it went wrong i'd lose loads of work inside a mess of plastic.  The mould that i've pictured earlier had to be thoroughly waxed with polish, then sprayed with PVA release agent to allow us to get the stator out of the mould again.  Pretty much like an anti-stick coating...  Then the first thing into the mould was a sheet of fibreglass cloth, onto which was painted a little resin with catalyst mixed in.  Then the coils were placed in and clamped into place so that we could put little pins in the inside edges to hold them firmly in place.

On the left is my dad measuring out talcum powder to mix into the resin to thicken it.  On the right, the mould is being filled up to the brim and the air bubbles poked out.  You can see the 10 red flex wires which will carry the electric current emerging from the resin.  Below is a picture of the outdoor workshop to disperse the powerful fumes from the styrene monomer in the resin.  Dave has done a lot of this stuff in the past, and mentioned that they used to gauge their consciousness levels and nip out for a bit of air if needed before falling over...  Before the world became obsessed with safety.  Probably rightly so!

Here's a picture of the mould completed with the lid clamped down, and the excess resin coming out the overflow hole.

14th February

I was pretty worried overnight about how the casting turned out, and had a day off today so got down to the workshop early and spent over an hour carefully prying the cast out of the mould:

Here's me looking pretty chuffed with the result which couldn't really have worked out better!  All that was left was to trim off the ragged edges of resin and then put the stator to the side as a finished piece. Next I got on with preparing the magnet rotor mould, by drilling through the steel rotor plates in which i had drilled 4 12mm holes, through the bearing hub.  Below is a picture of the parts of the mould located in the right relative positions by two 12mm bolts coming through from below.  The magnet positioning jig is shown here inside the mould, but that won't be part of the casting process as it is only to position the 12 magnets on the steel disks.

So far i've only made one complete mould and I don't think I have enough of the correct plywoods to make another one, so I'll have to do the casting carefully so that the mould can be used twice.  Below the picture shows the rotor on the left bolted on to the hub which allows it to spin.  On the right is the mould again with the other metal disk in it. clearly showing where the twelve magnets will be superglued.  With much care I might add!  So to get an idea of the structure of the thing - the newly cast stator will be mounted between the two magnet plates.  The magnet plates will have the blades directly bolted on to them on the front, and this will rotate the magnets past the coils in the stator.  That's the plan anyway...

There will probably be another delay before the next burst of activity, but hopefully not...  Until then c'est ca!!

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