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Picture of Cardboard Savonius Wind Turbine
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Goal: build a Savonius wind turbine made out of cardboard to see what
works. This is for the turbine only and not the generator itself. The main photo you see is the goal.

The need for a working model grew out of frustration trying to
jury-rig various designs of a Savonius turbine that in the end would
not turn at all in the wind.

Some Initial Botched Designs
Shown below are several botched designs. All four are attached to the drive shaft of a 24-volt DC battery-operated lawn mower. The vertical bar you see is an allthread bar that is attached to the motor shaft. The galvanized metal is half of a dryer vent tube. The first design would turn half way and then stop because of the resistance of the back side of it coming into the wind. I then added a top disk and attached a number of 2-liter soda bottles and some 1-gallon milk jugs to a disk on top. With a stong wind I actually got the mill to spin if I gave it a start. It has to be the ugliest windmill ever.

The second design is all cardboard and looked really sharp. it didn't budge an inch in a very strong wind.

In the third one I added parts of the dryer vent tube to the cardboard mill and that worked a little bit but there was resistance on the back side coming into the wind.

At this point, I decided that I had to go back to the drawing board with a simple model to see what had a chance of working.
 
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Step 1: Materials needed

Picture of Materials needed
The following project took me one hour from conception to finish and I
was making design decisions as I went along. I was amazed that it
worked perfectly. I guess it should work perfectly because it is the
design described in a number places. Of course, the coffee can and
soda bottle designs were said to work but didn't for me.


Materials:
a. A large piece of heavy-duty cardboard box
b. 14-inch dowel (or knitting needle, or something similar) to serve as an axis rod
c. 2 small rubber bands
d. Duct tape or electrical tape
e. Hot glue (optional)

What you see in the photograph are the pieces you are going to cut out of the cardboard. You can also see the knitting needle with some rubber bands on it.

Step 2: Make the vertical paddles

Picture of Make the vertical paddles
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Cut 4 strips of cardboard 4" x 10". These will be the vertical
paddles that catch the wind. Cut two rectangular notches in each
paddle. Each notch should be 3 inches long and just wide enough that
the disk will fit in snugly. These notches will be located 1 inch from either side of the ends of paddles.

Step 3: Cut the top and bottom disks of the turbine

Picture of Cut the top and bottom disks of the turbine
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You will need to cut two disks 10 inches in diameter. Since I flunked kindergarten, I found this somewhat of a challenge. Trying to draw a true circle without a decent compass is tricky. Then after you have drawn it and cut it, finding the true center is also difficult. Here's an easy way to do it.

1. Cut a 10x10 inch square of cardboard.

2. On all four sides make a mark half way between the edges. That mark will be 5 inches from the corners on each side.

3. Use a ruler to draw lines that connect opposing 5 inch marks through the center of the square. Where these lines intersect, that's will be the center of the circle.

4. Use a compass if you have one and jab it into the center and expand it out to end of one of the radius lines. Now draw a full circle with the compass. I'm not sure school compasses are big enough to do this. An alternative might be to get a ten-inch bowl or something like that and lay it over the square and trace the lines. You can also simply eye-ball it and make an arc from the center of one side the the center of the next. You may not get a perfect circle but I don't think this is too critical for the model we are making. In the real thing it may throw off the ballance.

5. Now cut the circle.

Step 4: Draw angle lines on the disks

Picture of Draw angle lines on the disks
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Now for a little geometry. Take a look at the first image. Notice that there is an Angle A and sides a, b, and c. Side c is the line that we want the paddle to line up with. Where we draw it depends on angle a. To do a little geometry on this let's cheat and use a web-based right triangle calculator.

Make use of the following url: http://www.csgnetwork.com/righttricalc.html My side b is 5 inches (the radius of the circle) and I chose to make side a 2.25 inches. Accoding to the calculator, this makes angle A 24 degrees. You can play with this calculator by either entering side a or angle A as you experiment with different configurations.

Going with my 24 degrees configuration, make a mark along side a 2.25 inches from the center of the circle and then draw side c. Now do that with the other three radius lines.

After that is done, do the same thing with the other disk.

Notice that there are short cuts in the disk at angle A on each radius line. The pupose of these cuts is dock the paddle to the disks. The cuts should be about a half inch and should follow the path of line c.

Step 5: Attach the paddles

Picture of Attach the paddles
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1. Double or triple up one of the rubber bands and push it up the axis rod to within about 2 inch from the top. The purpose of this and the other rubber band is to anchor the rod to the disk via friction. The also help to keep the turbine from slipping up and down.

2. Push the axis rod down through the center of one of the disks. I suggest that you keep the side of the disk with the angles drawn facing up for easlier alignment of the paddles.

3. Push the rod through the center of the second disk with the side of the disk with the drawn angles facing down. Slid the disk up the rod to within about 8 inches of the top disk.

4. Slide the second rubber band up the rod to within an inch of the lower disk.

5. Push one of the paddles onto upper and lower disks so that the notches on the paddle dock into the angled notches on the upper and lower disks. You might want to temporarily tape the paddle into place from the top and bottom.

6. Mount the other three paddles in same way.

7. Push the rubber band on the bottom up the rod so that it sits firmly up against the lower disk.

8. Now you can tape the paddles more firmly to the lower sides of the disks (the lower sides if you don't want the tape to show. As an alternative, you could use a glue gun to glue the paddles in place. Only do this after you have finished testing the turbine in the wind and are happy with the angles of the paddles.

Step 6: Test the wind turbine

Now you can test the wind turbine. Inside the house you can hold up lightly with both hands in front of a fan and watch it turn. You can see that the fan makes the turbine very easily. The outside video, unfortunately, was taken when wind was variable and blowing only about 3 mph.

The two videos that are attached I jury-rigged a setup so that the turbine could stand up by itself without being held. You can use your imagination as to how mount the turbine a little more permanently.

Experiment with different angles for the paddles to see what is the most efficient. I chose 24 degrees. Would 45 degrees work better? How about 10 degrees? You will notice that the smaller the angle, the better the paddle catches the wind on the left side. However, you notices that it also catches it too well on the right side. If you made the paddles 0 degrees, the turbine would sit idle in a strong breeze.

Where to go from here

The turbine, as is, probably could be used to generate a small amount of electricity in a school setting. The trick will be figuring out how to hook a small motor to it. You could also glue magnets to the bottom of the lower disk and then making coils of wire that remain stationary below the turbine.

What I want to do is make this turbine out of plywood and scale it up by double. I will use some of the material shown in the into to this instructable. Specifically, I will use the DC motor, the vertical allthreads bar that will serve as the axis rod, and the clamp I made to mate the motor and axis rod.

It will be interesting what kind of power I get out of the scaled up version. I would like to see if I could light up a series of LED's when the wind is blowing. That would look great at night. I might also try to use the power to pump water up over a waterwheel.

If you build this cardboard turbine, please post lessons learned and additional suggestions.
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AgoVeli1 year ago

This idea is very good, not that hard to make and no special curved surfaces neccessary. Now, the next problem is how to water proof it!

cglaw20131 year ago
it's ideala
rcisneros4 years ago
Computer fans don't have permanent magnets, so they won't work without modding them.
pretty much all of the computer fans I've taken apart use a permanent magnet mounted inside the plastic fan body. though you do have to mod the fan a little because most have speed control circuits that would get in the way... but it's usually pretty easy to see were each coil attaches to the PCB, stick some wires on those and run em to a rectifier and "Poof" instant generator..
That mod sounds like it would make a great Instructable!
they dont!
Yes they Do Cisneros. They use a Magnetic RING on the Flywheel.
So it is the MAGNET RING that turns with the Blades.

the Stationary part are the Electronically-Commutated Poles. (3)

But you do have to solder 3 wires on the Driven side of the windings.

This will be a 3 phase output that needs to be rectified with the proper rectifying bridge. for a DC output.
Good morning, I just was wondering once you make the modifications does is generate cogging thus making it harder to start spinning ?
I tried hooking it up to a little motor. It does turn on the light and the motor was small so it didn't seem to keep it from spinning. The whole thing didn't last though. I'd like to find a way to make a more permanent version.
srsudarshan3 years ago
What will be the output voltage?
manojkup5 years ago
How about trying with single round base and 4-8 CDs instead of cardboard for blades!! and it works.. I further modified the model with few more changes and it is sufficient for my project.
m3rk3r manojkup3 years ago
thx for the idea
rpushkar3 years ago
THE WAY YOU HAVE PLANED IT WAS VERY NICE
how can i make this power 2 LED lights with 1 motor. what kind of motor should i use
I might be banned 4 this, this wind turbine looks like a apeice of crap !!
rhakenb. Thanks! Used this instructable with a scout group. All the models worked and they loved your model. I am going to use wheel to raise a weight next it looks easily strong enough.
rhackenb (author)  recycledteenager4 years ago
Glad to hear that you could make use of the design with the scout troop. Maybe you could post some photos of what they come up with.
An easier way to get a good circle is to put a tumbtack in the center and tie a small string (dental floss would work good) and stretch it out to the end of the cardboard and tie a pencil to it.
we used to call that a "carpenters compass" exept we used a small nail and a scrap of paper from the edge of a sheetrock bundle. (useful for cutting curved radiuses in a peice of wood with a saw.)
Need more power ? Simple fix = hook several small turbines together with bicycle chain and a small alternator. OR make a larger turbine and hook it up to the alternator/generator with bicycle chain. These are just a couple simple/quick solutions of many more avail..... Also check out the local library.
Several options = 1. Hobby store & "Plastruct" sheeting - 2. Fiberglas sheets are purchased OR easy to make ( think 'boat work" ) 3. horizontal blinds
IETMN4 years ago
dude! this idea is good! would you be nice and send me the pdf file to my mail please? if so: stefymel@hotmail.com
I'll really appreciate if you send the file please!
iamaqtpoo4 years ago
This is so interesting, thanks so much. My son is 12, he has been speaking a lot about wind turbines lately so I think this will make a few awesome weekend projects for us. We unfortunately live in a not very windy area(Florida is more know for sun...oh well!) but, we will give this a whirl anyway. Thanks again so very much for your efforts, GREAT JOB!

good work !
such a gonna be great job ever
Astha Ag.4 years ago
I m making it in a science exhibition and i hv 2 submit it on Monday i.e. 9 August. So, will u pls arrange an image with a bulb with it or how to generate electricity from it??? Also, I wanted 2 ask u that about how many voltages can it supply???
rhackenb (author)  Astha Ag.4 years ago
Sorry, I have the wind turbine disassembled now. It never had a generator connected to it anyway. Maybe you can figure out a way to do it yourself.
You can make a simple mount for thses light weight prototypes out of tubing placed outside an axel shafting whitch can be driven into the gound . Once the shaft is plumbed if there is close tollewrences between the pipe and shsaft a single steele or ball bearing can be placed atop the shaft this acts as a piviot point and reduces the actions of friction on the rotors whitch will spin freely in a slight breese. Others were working on small gen set made from surplos computer fans others on larger generators5 volts to 12 volts goal being to charge any device 5 or 12 volt or charge 2 AA or 2 AAA batteries
rhackenb (author)  rapidprototyping5 years ago
The problem with any small motor like that is trying to physically mount the motor to the blades. Most small motors have a very small shaft to attach to. Take, for example, a fan from a computer. Mounting to that is very difficult.
thepelton5 years ago
I found that a good method of cutting and constructing parts at least for me is to use 1/8th inch birch plywood cut with an Epilog laser. I could probably make a functional one of these wind blade units with it. I'll have to try it.
You may want to test and see how it will do with a similar light-weight cardboard structure, but more designed to catch the wind while reducing drag. Perhaps add 4 more cardboard strips to the inside to give it a z like shape between blades. (the below drawing may be collapsed when I post this, just in case you see only a blob of slashes) | ____ | \ / / \------- | |
medius5 years ago
Now what is this hooked to that generates power?
rhackenb (author)  medius5 years ago
As I said in the instructable, it is not connected to anything. I was just experimenting with the placement of the blades. Something this small might be able to run something like the motor behind a computer fan.
omonile5 years ago
what generates the power.And what is the component?
mibbster5 years ago
How many watts did you second design produe? This is the design with blue things for the sails
beehard445 years ago
I was browsing on making turbine blades out of cardboard, and the regular turbine blade design wasn't that efficient. Stumbled upon this, hopefully it'll give a lot of torque to power my naughty stepper motor....
rockerape5 years ago
You missed 4 toes  :-)
foxwoodfarm5 years ago
I used form board that can be purchased at Walmart of craft stores. It is about 1.4" thick and is more rigid than cardboard. It can be cut with a box cutter,  scissors or exacto knife. The foam board is also weather proof for a long time. I made a PVC pipe frame for mine. Sorry I didn't take pictures 
MattM47735 years ago
this is my last comment
i would like to know how u mounted the turbine cos in the steps i didnt see anything about a mount and im not sure how i can present it without one
plz reply soon because its due this friday
rhackenb (author)  MattM47735 years ago
You can see from the two videos that the mounting is jury-rigged.  First of all, the bottom of the knitting needle is sitting in a large nut that has been taped down to the platform the whole thing is on.  The diameter of the nut is large enough to so as not to impede the spinning.  The nut was used to keep the needle from walking off to the side.

For the top I used a wooden paint stirrer stick.  It had a large hole in it and the needle was passed through it before it was inserted through the axis of the turbine.  This stick was sitting on a surface that was as high as the top of the turbine and had a weight on it to keep it steady. 

If you want to make this more professional, take a long strip of light metal such as aluminum.  Bend it in two places so that the top part reaches to the top of the axis and that bottom part reaches to the bottom of the axis.  You are going to have to use your imagination and creativity on this. 
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