Build Your Very Own Electricity Producing Wind Turbine - Basic with an off the shelf generator/motor.
There is nothing more rewarding and empowering than making a wind powered generator from scrap materials. Wind power is one of the abundant, clean, inexpensive, renewable, and easy to use resource. Most of the tools and materials that will be required to make your own wind turbine similar to this one can be found at your local hardware shop or junk pile. These are the five basic parts to a wind turbine:
- A generator
- A mounting that keeps it turned into the wind
- A tower to get it up into the wind
- Batteries and charger controller
Material and supplies that you can use for the basic parts
- Motor to use as a Generator or a Generator
- Large plastic pipe 4”+ - to use as blades
- Square metal tube for the base
- Couple pieces of scrap metal
- Nuts and bolts
- Pipe or pole to use as the tower
The generator is the core of your wind turbine, we will be using it to generate the electricity. Most motors can produce electricity when spun, some are slightly more complicated than other though. The best kind of motor is permanent magnet brushed or brushless motor. Permanent magnet types work well as generators. Also, they don't normally require high RPMs to get some usable power out of them. To find out if your motor or generator will work, look on the label and find the RPM. Then, find the working voltage. Divide RPMs by voltage to get RPMs per volt. This is known as your (k of v). For a small wind turbine you are looking for something around 25 RPM per volt. The more RPM per volt, the faster wind turbine will need to turn to charge a battery, which means you will need faster wind before it will start charging.
One of the most popular motors to use is the Ametek 30, its works great, it was an old computer tape drive motor. Those Ametek’s are really hard to find now and very expensive. I found myself a good treadmill motor off eBay. Not all treadmill motors will work good in low wind, mine was rated for 1700 RPM at 260 volts or .15 Volt per RPM. This means that the motor will have to spin at least 80 RPM to get 12 volts out to charge my battery. My motor also came with screw on hub.
Hopefully the motor you choose has a hub attached. If it doesn't, you'll have to find something else that works. Circular saw blades, HDPE plastic, piece of scrap metal, pulleys, and hubs from something else might work, but remember your wind turbine can get up to several hundred RPM, so whatever you choose get that hub on tight and secure!
The motor should be easy to turn by hand, and it should produce a bit of voltage with a hand turn. Something in the range of 1-2 volts with a hand turn will be great. If in doubt, hook the motor to a lathe, or drill press, or another motor to get a good representation of what it will output at a set speed. If the machine can't get voltage out of it, neither will the wind.
The blades I made are designed to be cheap and easy to make. That being said, blades can be very dangerous. My suggestion is to use the thickest material possible, and if its vulnerable to UV damage, like PVC, paint it. I recommend making your blades from 5” or 6” pipe, ABS or PVC. I have also heard that green sewer pipe that is 3/8” thick makes great blades that are durable. If you want to do nice ones, I recommend making out of fiberglass, much stronger. I would make a simple mold and use a foam core, use about 6-10 layers of woven glass.
Before choosing your blade design and material think about your average wind, light breeze, strong wind, hurricanes. You will get a lot more out of your wind turbine if your blades are designed for your kind of wind. As a general rule longer blades will help start the generator at lower wind speeds, but the output on the high end will be lower. Also the long the blades the less the speed(RPM) they produce, so in 5 MPH wind 20 in blades may spin at 80 RPM as 10 in blades spin at 130 RPM. If you only get small breezes, then make your blades wide and long, and maybe add an extra one. If you get hurricane winds every day, keep the blades short and thin, and you will easily produce a lot of power with that wind turbine.
Making PVC/ABS Blades
These instructions are for 24” blades made out of 4in ABS pipe.
If you are using black pipe, use a paint pen or white pen to mark it.
1. Place the 24" Length of ABS pipe and a straight edge(ruler works fine) side by side on a flat surface. Push the pipe tight against the straight edge and mark the line where they touch. This is Line 1.
2. Tape 3 sheets of 8.5x11 paper together, so that they form a long, completely straight piece of paper. Wrap this around the section of pipe at each of the two the marks you just made, one then the other. Make sure the short side of the paper is straight along Line A and the paper is straight against itself where it overlaps. Mark a line along the edge of the paper at each end. Call one Line 2 and the other Line 3.
3. Start where Line 1 intersects Line 2. Going left around Line 2, make a mark at every 5 ½”. The last section should be only be about 4 ½”.
4. Start where Line 1 intersects Line 3. Going right around Line 3, make a mark at every 5 ½”.
5. Mark each line using a straight edge.
6. Cut along these lines, using the jigsaw or band saw. I recommend a speed controlled jigsaw so you don’t melt the plastic as you are cutting it. You should get 4 blades, 3 blades 5 ½” and on small scrap.
7. I recommend cutting a notch for bolting it, at least 1 1/2” in width and 1 ½” long.
Sanding the Blades
Although by the angle they were cut creates an airfoil, you should sand the blades to achieve an even better airfoil. This will increase the efficiency of the blades and making them quieter. The angled (leading) edge wants to be rounded, while the straight (tailing) edge wants to be pointed. Any sharp corners should be slightly rounded to cut down on noise.
Getting Blades on to the Hub
My treadmill motor came with the hub attached. This hub unscrews clockwise, which is why the blades turn counter-clockwise. My hub has cooling fins which made it harder to bolt to it, since I recommend sealing the motor completely I would just grind them flat. (please note: if you remove cooling fins then the current rating for the motor will be lower.)
1. Make a template of the hub on a piece of paper, using a compass and protractor.
2. Mark 3 holes, each about 3” from the center of the circle and equal distance from each other.
3. Place this template over the hub and punch a starter hole through the paper and onto the hub at each hole.
4. Drill these holes to the size of your choice, I would recommend ¼” to 3/8”.
5. If you are good at tapping holes then I recommend tapping, if not just use nuts. Make sure you at least a lock washer to keep them secure.
6. Bolt the blades onto the Hub. At this point, the outer holes have not been drilled.
7. Measure the distance between the straight edge of the tips of each blade. Adjust them so that they are all an equal distance from each other. Mark and punch each hole on the hub through the empty hole in each blade.
8. Label the blades and hub so that you can match which blade goes where.
9. Remove the blades and then drill and tap these outer three holes.
10. Bolt the blades back on, and your done.
Protect the Generator
I recommend making some kind of protection sleeve or enclosure to protect your motor. A PVC pipe that is large enough to fit your motor will work fine. I used some very light gauge aluminum and RTV and made a little motor enclosure, I found both at my hardware store. I also made cut outs of the aluminum and put them front and back then sealed them with RTV.
Mount and Tail
The mount and tail should be sturdy. Weld the mount to the yaw pipe, if at all possible. Also, make sure your tail is on there good. If it vibrates, then add a bolt that goes all the way through the mount.
I purchased a 1x1 inch square stainless tube for my base, you can also use aluminum or cheap steel if you paint it. My motor had two mounting spots on it and I decided to use them, I just took it to my local hardware store and purchased the right size bolts. Drilled the holes in to the my square tube and bolted it together. If you don’t have good mounting holes I recommend purchasing large U-bolts or good hose clamps to mount it to the base. You may want to make your protective sleeve over you mountings too.
Tails are not a big deal, but the bigger the better. It needs to be square with the blades, so it points them straight on into the wind. I purchased a small square of sheet metal about 20 gauge and cut it into my desired shape of a tail and used sheet metal screws to attach it to the base. You can pretty much use anything you want but I would recommend plastic or metal. Don’t get something to flimsy that will make noise and wiggle your wind turbine when it’s blowing. The 20 gauge sheet will wiggle and make some noise in high winds and I would recommend something thinker. 1/8 acrylic (Plexiglas) should do if you keep it small.
When placing your mount to the base make sure you that it will be balance. You need some way of making your mount be able to swivel. There are lots of different things you can use. I went to the plumbing department and found a floor flange for 1 ¾ pipe made out of heavy pot steel, and then I found a swivel pipe unioner to allow the turbine to yaw. I bolted the flange to the base. To make the unioner swivel I just greased the inside and then used some JB weld to hold the parts losses enough to move but not come apart and allowed to cure. I used a nipple to attach the unioner to my flange and then the flange would screw into my tower.
Balancing your blades
Before getting ready to put your wind turbine out, balance your blades. This will stop vibration, noise, and make your wind turbine more efficient at turning wind power into electricity. You can easily do this by placing the turbine on a flat, level table. Spin the rotor with the blades on it, if one blade is heavier or slightly out of place than the others it should fall to the bottom. Lightly trim the end or give additional sanding until all blades are even and balanced. If you have a real balance I would recommend using it, but if not this way will you can get it close, really depends on how nice your bearings are in the motor.
You need to get the electricity out of the motor and off the tower, select a proper gauge of wire and run it down or inside your tower and connect it to your wind turbine.
Make your tower good and strong. I used some scrap 1 3/4 inch water pipe which was treaded so it was easy to simply screw together. Bury your tower and cement the base and then install guy wire, the rule of thumb is every 15ft of tow you need guy wires twice the height on the tower it being attached.
Please read the Safety Guidelines before starting building your wind turbine.
The finished turbine on a temporary tower: