I would like to build my first wind generator and have been looking for plates to make the magnetic rotors. I have found a 13 inch pulley off a combine, it has a 3.5 inch hole in the center. The pulley is actually two plates riveted together,each plate is 3/16 thick. If separated each disk could be used for a dual rotor generator. The inside dimension is 12 inches to the tapered lip. The raised lip is just over a 1/2 deep and it would make a perfect dam for the resin when setting the magnets... no mold used. My question is will 3/16 be thick enough for the 12 inch rotor. I know there a many different types and sizes of these pulleys available for almost nothing.