Parametric helical Darrieus vertical axis wind turbine - Mk2

Second iteration of the Vertical Wind turbine.

There is a new version of this design, that has much promise.
http://www.thingiverse.com/thing:15083

In order to get the design greener, the blades have been hollowed out in order save on plastic. Added M8 nut recesses in order to couple the turbine to a M8 threaded rod. The rod serves as a bearing carrier and drive shaft to the generator.

Added STLs