FINAL BALANCE OF HOME MADE WIND TURBINE BLADES

The chain drive has been removed to allow the rotor to spin freely. The heavier blade(s) will rotate to the floor and a determination can be made as to which point of the rotor is heavier. But when using natural wooden blades, there will always be differences in the natural wood product. Our blades were made out of 3 longer boards that were within a few pounds of each other before we cut them in half. So we gave ourselves some advantage in the beginning. We want all of the blades to be identical but this is not possible. By using the same board in this case we get at least two similar structured blades from the same board.
If you look towards the end of one blade there is a small circle. This is the light blade that wanted to rise to the top of the rotor. We have taped a metal disc of approximately 1/4 pound in the center of the blade. It is moved until the perfect spot is found on the lightest blades that best balances the system. When the blades can be placed in any position without rotation then the balance is close. Our initial objective is to use the smallest weight possible as close to the end of the tip of the light blade as possible. Always maintain the center of the blades and use a round object for weight whenever possible. Then a measurement is taken from the center of this weight to the center of the rotor and multiplied together. In our case this was 54 inches x .234 lbs = 12.64 inch pounds to the center of the shaft. Then we make a plate which will bolt to the metal bracket on the wooden blades near the rotor. In our case, 16.25 inches was the center of our bolt holes to the center of the rotor shaft. Then we divide so that 12.64 inch lbs / 16.25 inches = .78 lbs at that point on the rotor blade bracket. a 4 x 4 plate of ~ 1/4 inch thickness was bolted to the bracket and a static balance was completed. The final test is to slowly spin the blade and precisely get the blade to stop slowly without recoil or continual drift. In a system more than 13 feet across this is less than the weight of one bolt used to secure the blades to the rotor. Which is how we complete any final adjustments. Balance is critical.