We manufactured the wind turbine spinner by first manufacturing a positive, and then a negative mould. It was difficult to make the surface aerodynamically smooth enough, but happily we succeeded in the end.
Building the original mould
As you can see this body does not look like it has the aerodynamic shape of a spinner. To make the spinner we first build an original mould out of the styrodur plates. Again drawing the different circles on each side, cutting out the bigger one and make it even throughout the thickness of the plate to the smaller circle. Only tiny measurement mistakes in drawing the centers made our spinner look like this, even grinding it did not really help. Only working on it on a turning lathe made an aerodynamic shape. To overcome the gaps between the plates and to become a surface resistant to all the further layers we put on some epoxy putty.
We thought it would be easy to just put it on a turning lathe again but nobody wanted to have the noxious epoxy powder in their workshop.
We tried to work on it by hand but it was impossible to get a nice surface.
After asking a lot of people we finally found a carpenter who let us work on his woodturning lathe. We thought of many ways to get this spinner more easily but all other ways did not seem to work out or are even more complicated or more expensive.
After we had the spinner on the turning lathe it still had a lot of holes and very uneven parts where the putty was too thin at the beginning. So we put some candle wax on the holes, cut off what was too much and evened the surface by heating the wax up again with a hot air gun. Doing this with most of the holes took another few hours but made us a really nice surface to work with and the surface was so waxy that even the release agent did not hold on the spinner anymore. So all in all, a good pre-condition to get the negative mould of the spinner.
Laminating the negative mould and the wind turbine spinner
So, once again. 4-5 layers of seperating wax, and a layer of release agent, then a layer of gelcoat and after this two hours of laminating the negative mould. This time we cut the fibre glass in triangles, we still tried to use the thick fibreglass as well but we gave up pretty soon and only used the thin webbing. After leaving it to dry for 24 hours we got the mould of the spinner with the help of some high preassure air. Once again we smoothened the surface of the negative mould before we started all over with the barrier layer for the final component.
Being “experts” now we used even smaller triangles of the webbing, they were a lot easier to work with and you cannot see a difference to bigger pieces.
Also we only used the thin webbing, even though we only made 3 thin layers the spinner had enough stability at the end and was even lighter than first planed. After the drying process we had to cut the edges with a “Dremel” again and built the construction to connect the spinner with the rotor inside. For the connecting construction we drilled holes in pieces of wood which we then glued with epoxy putty into carbon pipes. We screwed the carbon pipes on a piece of wood in the correct distance of the holes on the rotor. We built our construction with styrodur and epoxy putty around the pipes and inside the spinner to connect the spinner and the pipes. Finally we disconnected the spinner from the wood and “tada” it matched the wholes on the rotor.
About the author:
I am studying Renewable Energy Tecnology at Flensburg University of Applied Sciences. Wind Energy is a big part of my studies so I was more than happy to participate in this project and do some practical work. My job was to manufacture the aerodynamic body of the turbine.