Green Loops ran a similar course back in May 2002, when I taught them to build a brakedrum wind turbine. This time we were in the Jump Ship Rat gallery, which is a big space (rather cold). We were joined by Hareth Pochee (seen below) an engineer from Max Fordham. We built one machine - 2.4 metre diameter - and we erected and tested it at the end.
The brakedrum machine came out on display
The wood we had was also interesting. It came from exercise bars
in a gym. Very nice pine but with a curves edge, and slightly under
the specified width. Dan marking and cutting the width.
It worked out nicely once we had got a plan sorted out.
Chris gets into the fine stuff with a spoke shave.
Danny sculpting the thickness down
Ralph finishing a blade and cutting off the tip. Its a good idea
to start with a piece of wood that is too long, and finally cut off the
Danny drills the holes for the mounting bolt to pass right through.
Chris winding coils. Note the new steel bearings on the coil winder
that provide a more precise control of the bobbin. We did not use
a shaft support for the reel of wire because it was so large that the wire
came off the side of it without appreciably twisting.
Becky soldering up the stator.
Mick cutting out moulds.
The mould base and lid were very thick, so we were able to use relatively widely spaced bolts to clamp them together instead of the usual screws. The bolts did get resin on them so it was not a massive improvement, but in some ways it was simpler than multiple screws.
Ralph tightens down the bolts.
The mould needs some time in front of the space heater.
Now the magnet rotor castings.
Nick and Chris pour in the resin.
The stator comes out very neatly (apart from the ragged edges, which
are easily smoothed off).
Drilling the mounting holes in the stator, using the plywood template.
The rotor castings took a bit of hammering to get out of the moulds.
Welding and fitting the tail.
And the vertical piece on the end.
Dan fits the stator. The flexible conduit makes it much neater.
Mick spins the completed alternator.
Balancing the rotor blades.
On site now, installing the wiring before lifting the machine onto the tower top. The diecast aluminium box on top of the yaw bearing makes for a very tidy wiring job.
Not much wind available but we got a few amps out of it. Lovely sunset over the Mersey.