DIY Alternator - Rotor Hub
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The centerpiece of my alternator design is a standard bike hub. This is the thing that is at the middle of the wheel of just about any bicycle sold worldwide. They are generally pretty standard, but make sure you look for a hub that comes from the rear wheel. These generally have a heavier thread. Also, always use a hub that is a solid axle. There are some that have a hollow axle, but since the whole rotor assembly is going to weigh upon the axle, I think it's better to go with the more sturdy option. Most hubs aren't going to have so much thread on one side, so you will probably need to spin the axle until almost all of the thread in on one side. Also, make sure you find a hub that has enough thread! It needs to fit through approximately 3.8cm (1.5") of wood.

The other part of the rotor hub is a 1.25" pipe flange. This piece will be JB welded onto the side of the bike hub with the least thread. The flange serves two purposes. It is a place to glue the PVC part of the rotor onto the hub, and it has four holes pre-made to place bolts that will be used as a way to attach the blade hub. I actually have the flange backwards in the picture below, but it gives the basic idea. I used four .635cm (.25") bolts that were 10.16cm (4") long.On the other side of the flange for each bolt is a nut that keeps the bolts tight to the flange.

Mix up a good amount of JB weld

It's a good idea to use quite a bit of JB weld. This is a very important piece and it's going to experience its fair share of force.

After adding the pipe flange, make sure it is aligned well and clamp it down. Let it sit for at least 24 hours before spinning it. As a note, in this picture, the bolts will be extending upwards out of the pipe joint.

The other side. It looks perfectly aligned! If it isn't, the whole turbine will shake, so make sure this is good.

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