Posts Tagged ‘Diameter’

Your homemade wind generator must be able to spin freely to face the wind at all times. The horizontal axis that the hub assembly sits on, must interact with the vertical axis of the tower in such a way that they are held secure, but will also spin to meet the wind direction.

You can use a simple bungee cord mounted between the pipe and the body of the generator to keep it from spinning around erratically and twisting up your charging wires. With a bit of plumbing supplies and some ABS (or PVC) pipe we can accomplish this goal quite quickly.

First we will assume that at the top of your tower is a vertical section of pipe. Your entire tower might be steel pipe that you have managed to find. Use at least 2 inch pipe for this purpose.

On top of this pipe, the wind generator assembly must sit, and be able to spin. We usually mount a simple flange assembly on the body of the wind generator for the pipe to fit into. Make sure that the flange holds at least 3 inches of the pipe from the tower, and that it will move easily. We do at times weld a 10 inch piece of pipe onto the flange for strength. It really depends on the wind generator size.

If you are building a wind generator more than 6 feet in blade diameter then add some more strength to the flange for safety.

The body of your homemade wind generator

First off locate a piece of ABS or PVC pipe that the DC motor would fit snugly into. This will depend on the size of the motor, but most will fit inside of a piece of 6 inch pipe quite nicely.

Cut the piece of pipe 2 inches longer than the DC motor. Next, you will fill the blade assembly end with a piece of wood with a hole cut in the centre so that the shaft of the motor can extend out. The shaft has to connect to the blade assembly eventually.

Before you put the DC motor inside this permanent weather shield you will need to attach the 3 inch flange to this piece of pipe. Keep the flange mount as close to the blade assembly as is practical. Consult with the Tilt-up assembly drawing below to make sure you get this part right.

Remember, the blade assembly is very heavy and you will want to balance the whole affair atop the pipe from the tower. A bit of experimentation will be necessary to achieve balance.

You should be able to find PVC fittings to reduce the 6 inch pipe that houses the DC motor down to a 3 inch pipe for the tail assembly. Attach the two together. A tail length of about 2 to 3 feet is quite adequate.

In our next post we will discuss how to build the tail.

If you want a complete blueprint on how to build a home made wind generator, check this site: Build a Homemade Wind Generator

Start by quartering a 48 inch long piece of pipe around its circumference and cutting it lengthwise into four pieces. You can check the post on How To Cut The Blades for this.

This will end up being a wind generator blade assembly of just over 8 feet in diameter. Adjust your lengths according to your own preferences.

Remember that you will need a blade diameter of approximately 8 feet to achieve an output of 1000 watts with a 20 mile per hour wind speed. A couple things you should remember though. The most important is the tremendous force the wind can place on your equipment if your blades are too big. Let’s assume a wind speed of 55 miles per hour, that’s really a common speed out there. If your wind generator blade assembly has a diameter of 3 feet the force on the blades is approximately 115 pounds. But, if you up that blade diameter to the 8 feet (we recommend for most projects) the force of the wind on your wind generator at a wind speed of 55 miles per hour is an incredible 840 pounds of force.

Now, your blades are not catching all of that force of course, but they are catching a great deal of it. We design our wind generators to handle these forces. Design your tower, blade and hub assembly with that in mind. Light is good for spinning, but strong is better. It is sometimes hard to strike the right balance, but new materials and sometimes some surprisingly old materials make the choices easier.

Attaching the blades to the hub

The pulley that makes up the central part of your hub assembly must fit tightly on the shaft of the DC motor. The hub assembly must spin the DC motor in order to produce power.

We usually drill a hole through the pulley and shaft and insert a small one eight of an inch bolt and nut to hold the two together.

On the pulley (hub) you will have to measure the circumference, or distance around the outside of the pulley. For a three blade assembly you will divide this number by 3 to give you the distance between the blade mounting pieces of steel.

The following diagram shows the placement of the steel on the hub for use with PVC blades.

Note: when using wooden blades make sure to use 1 inch angle iron so that the blades are mounted at an angle to the wind. We have found 1 inch by 2 inch works about the best. The blades should be mounted at an angle of about 10 degrees to the wind.

The steel should be drilled with a one quarter inch drill bit at the same position on the hub for each piece. This will vary depending on the hub material used. The above diagram gives you a good idea of how to do it. Keep the holes at least one inch in from the outside if possible for strength and they should just meet at the centre of the hub. Take your time during this process and you will have a wind generator that is well balanced and spins well. You will be glad you did.

Mounting the Blade Assembly on the DC motor

First we need to do a bit of testing to see if your blade assembly is balanced. Just place the whole thing on a shaft of similar size and give it a few spins.

Make a note of the place it stops each time. If you notice that the same blade is always facing down at the end of each spin, then it is a wee bit heavier. Just give it a quick trim until none of the blades consistently stops at the bottom.

You can now do a test mount of the blade assembly on the shaft of the DC motor.

In our next post we will cover how to build a mount for the DC motor. Stay tuned

We recommend using two different blade materials. You can use the one that fits your budget or the one that is most readily available.

First off, we recommend PVC plastic sewer pipe in the 8 to 12 inch range to make the blades. The great part about using this large sewer pipe is that it is usually available at large city construction sites for free. Simple ABS pipe works well too.

Look for pieces in the 4 to 5 foot range if possible. You will want to build a wind generator with blade diameter of around 8 feet if possible to produce the most power you can with your DC motor and you will need at least 4 feet long blades to do that.

The PVC sewer pipe, if you had to buy it, comes in 16 feet length and costs about $183 per section. Kind of expensive, so those pieces you have in your hands are very valuable.

Why use PVC?

We have tried many types of pipe, from ABS to thin wall PVC, but nothing seems to hold up like this green or blue sewer pipe does. It is thicker and stronger than other pipe and all it requires is a coat of UV (ultra violet) resistant paint to keep going for years.

One note of caution, if you use this kind of pipe you will not achieve the kind of efficiencies of design inherent in using wooden blades. The main reason for this is because the pipe is rounded. The wind does not flow nearly as well off of a rounded blade as it will from a flat wooden blade. You can, of course use ABS or the thinner PVC if it is available. Try to find free sources if you can.

You will have to paint those blades. The only drawback to using PVC sewer pipe, or any pipe for that matter, is that it was intended for use below ground or inside. Thus, you will need to paint the pipe sections of your blades with a tough UV resistant paint to combat the nasty effects of the sun over time. The PVC pipe will get brittle and crack over time. This can be a very dangerous situation when your wind generator is spinning at high RPM and little (or large) pieces of the blades start flying off. Be careful.

So, paint the blades with a UV inhibitor. The main ingredient in most of these paints is Titanium Dioxide. Just look for that in the can. Ask at your paint store or hardware store and tell them what you are painting, and what you are looking for. This is not a hard to find product, even though at first glance it may seem that is the case.

You can check the recommended ebook Build a Home Made Wind Generator

In our next post we will discuss how to cut the PVC blades. Stay tuned