Summary

This is a remix of a smaller model. Scaled up by a factor of 2.085 to accommodate 12" blades. All parts scaled to fit and use #6-32 and 608zz bearings and a 5/16"-18 threaded rod.
It kinda works...I believe the blade design is better suited for higher winds. Probably work on a design for lower speeds that will increase the diameter most likely.

UPDATE 8/15/2014: So I learned myself some stuff about bearings and realized thrust bearings were better suited for this project. I designed a printable thrust bearing that uses BB gun pellets as the bearings and works great. http://www.thingiverse.com/thing:429990