With the rotor metalwork completed and the layout of the magnets done, it’s time to cast the rotors in fiberglass.

I have no doubt that these magnets would hold fast to the backing plates by their own strength & with the bead of CA adhesive around each one… and then embeding them in epoxy fiberglass, but I’m giving the outer edge a few wraps with fiberglass reinforcing tape. It will hold a magnet in should one start to slip from the rotational forces but will also help prevent any minor long-term stress cracking.

Nothing jumps together by itself and there’s two rotors that need to be cast. We could make one mold and re-use it to pour each rotor, but while I was at it, it is just as easy to make two at the same time and then pour both rotors at the same time. 

The base of each mold is a 14″ x 14″ piece of 1/2″ plywood because I had 1/2″ on hand ;) , but since the rotor backing plate is 1/4″ thick and the magnets are an additional 1/2″ it was necessary to use 3/4″ plywood for the center piece with the 12.5″ hole in it.  

The smaller 2.5″ disc has a 1/4″ hole in it’s center to slip it over the 1/4″ centering pin (bolt) and will center the rotor in the mold. All the edges – inside diameter and out - have been slighty tapered with a sander to facilitate easy removal once the ‘glass cures.

The 6″ x 1/2″thick circles get placed caulk side down on top of each rotor (see below). The caulk should prevent any fiberglass from seeping into the mounting surfaces and bolt holes.

Pour.

 

Work out the Air.

 

Add a layer of cloth.

Work in the Cloth. Work out some more air.

 

Top it off.

 

I could’ve used C-clamps to hold the lid on just like when I cast the stator windings, but since this mold is full of magnets the extra work wasn’t necessary. Any metal will sufice as a clamp.

Removed from the mold and safely stored (away from metal filings, etc) until the machine gets assembled

Tags: Wind Turbine

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