PVC Wind Turbine Blades
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For PVC blades, you need a length of 8" diameter PVC pipe. This is a little difficult to find, surprisingly. It is not generally sold at hardware stores, although it is possible to find extra pieces at construction sites. Smaller diameter pipe does not work because it is too sloped to provide an acceptable angle of attack for the blade. Generally, the 8 inch pipe comes in a greenish color, although sometimes it can be found in black.

The advantage of using PVC pipe for blades is that by cutting diagonally down the length of pipe, you get a natural curvature in the blade. It is areodynamically advantageous to have the tip of the blade be less angled than the base of the blade.




To start, cut the PVC pipe in half, using either a hacksaw or ideally, a jigsaw. A skill saw or sawzall would also work here, although the cut is rougher. Try to get the halves to be the same size. Cut each half to the length you would like your finals blades to be.



Cut the halves into half again, giving you four quarters of the pipe. Each quarter can be made into a blade.


This gives the exact dimensions




Cut the blade out using a jigsaw, or if you don't have one, a hacksaw. It doesn't have to be the smoothest cut, because you'll be sanding the edges pretty significantly.


The resulting cut-out


You may notice that the cut-out blade is pretty fat and un-areodynamic. Before using it, you need to round out the sides and the tip of the blade, which will make it both more efficient and much quieter. You need to take a pretty significant chunk of PVC off, so it's best if you use a belt sander. Mine unfortunately broke while I was sanding the first blade, so I switched to a rasp (basically a really agressive file) for the rest of them.  Round all of the edges of the blade except those on the piece that will be connected to the hub. It helps a lot if you put the blade in a vice before trying to sand it.


A close-up on the rounding of the blade



This picture shows the smooth middle section of the blade versus the rough ends.



Next, mark two holes near the base of the blade to be used to fasten the blade onto the hub of the turbine. You want these holes to be as near to the trailing edge of the blade as possible. I left appoximately 1 cm of clearance between the holes and the edge.



I bolted the blades onto the hub. Make sure you use washers on both the front and back side of the hub. (That is not the case in this picture)


Make sure the nuts are on TIGHT on the back of the hub. Ideally, I would have used larger nuts, washers, and bolts to hold the blades on, but I had a lot of this size handy.


The finished assembly.



Unless you made the blades very precisely, they will likely not be very balanced on the hub. To solve this problem, I would set the blades up on the turbine and let them rotate freely. If they were unbalanced, I would tape a washer on the lighter blades and move the washer up and down the length of each blade untill they were adaquately balanced. I would then expoxy the washer to the blade.

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