In this project, you will build a small, vertical-axis wind turbine, or VAWT for short. VAWTs are not as efficient as their horizontal-axis cousins, but they are better suited to urban environments where wind can come from all different directions. The turbine will use energy from the wind to turn a motor, and the resulting energy will power up some light-emitting diodes (LEDs) within the base. The lantern will use this electricity to create a flickering, glowing indicator of the wind.
LEDs and other diodes allow current to flow through them in only one direction. The challenge here is to design a circuit that directs energy generated in each wire coil through an LED in the correct direction, no matter which way the lantern spins.
Adapted from D. Roberts, Making Things Move: DIY Mechanisms for Inventors, Hobbyists, and Artists, McGraw-Hill Education, 2010
Things You Will Need
|1||Stepper motor||SparkFun ROB-09238|
|1-MΩ variable resistor
|1||Breadboard||All Electronics PB-400|
|Jumper wires (or hook-up wire to make your own)||SparkFun PRT-00124|
|1 or more||LED, yellow or any other color||SparkFun COM-09594|
|1 or more||1000 μF capacitor||SparkFun COM-08982|
|1||1/4-in acrylic plastic sheet about 15 x 30 in or equivalent*|
||10-in wide aluminum flashing (usually sold in rolls)|
||5-mm bore shaft collar with set screw||McMaster 57485K65|
||1/2-in bore shaft collars with set screws||McMaster 6166K25|
||18-in length of 1/2-in outer diameter aluminum tube||McMaster 1658T45|
||Flanged sleeve bearings for 1/2-in shaft diameter||McMaster 2938T12|
||Thrust-bearing cage assembly for 1/2-in shaft diameter
||Matching washers for cage assembly||McMaster 5909K44|
||Socket head cap screws, 1/4 in - 20 thread, 3/4 in length||McMaster 92196A540|
||Lock washers for 1/4-in screw size||McMaster 92146A029|
|6||Flat washers for 1/4-in screw size||McMaster 92141A029|
||M3 screws, 40-mm long||McMaster 91292A024|
||M3 washers||McMaster 91116A120|
||Personal protective equipment (safety glasses, dust mask, and gloves)|
- Hacksaw or lathe
- Deburring tool and/or rounded file
- Coarse sandpaper
- Epoxy putty
- Set of inch and metric hex (Allen) keys
- Soldering equipment
Before you start, you may want to review the online guide on this project for full documentation. This project should take less than an hour to build, once you have all the parts purchased and/or cut, and laid out. This video shows the final product in action.
1. Order or make the gears, disks, and sail holders. You can download a free template for these parts at Thingiverse.
2. BE CAREFUL! Put on your safety glasses and cut an 18-in length of the aluminum rod with a hacksaw. Use a deburring tool or file on the inside and outside of the end of the rod to smooth it and avoid cutting yourself.
3. Make sure your aluminum rod fits through the flanged sleeve bearings, thrust bearing and washers, and the shaft collars. Look at the tolerances of all the parts. A tolerance is the amount of variation permitted or "tolerated" in the size of a machine part.
- The aluminum rod has a +/- 0.025-in outer diameter tolerance, which means it can range from 0.475 to 0.525 in.
- The shaft collars don't give a tolerance for their inner diameters.
- The flanged sleeve bearings say +0.001 to +0.002 in for the inner diameter. This means they will be between 0.501 to 0.502 in.
- The thrust bearing says 1/2 in +0.002 to +0.007, which means the inner diameter can range from 0.502 to 0.507 in.
- The thrust washers don't give any tolerance for the inner diameter.
The outer diameter of the aluminum rod needs to be smaller than the smallest possible part it needs to fit into, which is the 0.501-in sleeve bearing.
4. BE CAREFUL! If your aluminum rod is too big for the sleeve bearing, then put on your safety glasses, dust mask (aluminum dust is not healthy), and gloves. Grab the aluminum rod with the sandpaper and rotate it while you squeeze until you see aluminum dust coming off. Continue this until the rod fits through all of the components.>
5. Assemble the base. Start with the two disks, the hex standoffs, and the 1/4-20 screws, lock washers, and washers. Install the standoffs by sandwiching the acrylic disk, a washer, and a lock washer on each end with a 1/4-20 screw (see Fig. 1).
6. Install one of the flanged sleeve bearings in the center hole of the base disk. The base is the one without the four holes to mount the motor.
7. Rest a thrust washer, thrust bearing, and then the other thrust washer on top of the flange. The inside of the base will start to look like Fig. 2.
8. Slide the aluminum rod in from the top. Before it hits the sleeve bearing on the bottom, it should slide through the other sleeve bearing, a 1/2-in shaft collar, a laser-cut gear, two more 1/2-in shaft collars, and finally the thrust washer, bearing, washer stack.
9. Pull up slightly on the aluminum rod so it's not hitting your work surface. Use your Allen key set to tighten the set screw in the lowest shaft collar. At this point, the shaft collar is resting on the thrust bearing and attached to the aluminum rod, so you should be able to spin the rod.
10. Lift the next shaft collar from the bottom up with the gear to about the halfway point inside the base. Tighten the set screw. This shaft collar will be attached to the gear with epoxy putty later, but do not do this yet.
11. Secure the top sleeve bearing with the top shaft collar, as shown in Fig. 3.
12. Before you continue up the rod, this is a good time to mount your motor. First, cut the wires to about 8 in long and solder a set of four male headers to the wires. Red and green should be next to each other on one side, and blue and yellow on the other.
13. Remove the screws that hold the motor together. Use the longer M3 screws to mount the motor from the back, on the underside of the top disk. Sandwich an M3 washer and lock washer with each screw (see Fig. 4).
14. Slide the other gear onto the motor shaft and use the 5-mm shaft collar to secure it temporarily. Adjust the height of both shaft collars until the gears are at the same height and mesh well. Now you can break out the epoxy putty and secure the gears to their respective shaft collars.
15. Continue up the aluminum rod. Slide on a 1/2-in shaft collar, one of the plastic sail holders, and then another 1/2-in shaft collar. Pull the lower shaft collar up so it's not resting on the top of the base, and secure it to the rod with its set screw. Then, pinch the plastic sail holder with the shaft collar on top of it, and secure the assembly with a set screw. When you rotate the whole assembly by the shaft, it should rotate smoothly, and the sail holders should rotate with the shaft.
16. Cut out three sails for your wind turbine to catch the wind. There's no single correct method here, and you have a few different slots in the sail holders, so just use scissors to cut the aluminum flashing to a length you think will work. Then, cut 1/2-in tabs into each corner to slide into the slots. Bend over the tabs to secure the sails (see Fig. 5).
17. Do the same shaft collar, sail holder, shaft collar assembly on the top of the sail to finish this section of the build. Your project should now look like Fig. 6. It should spin with very little friction when you turn it by hand with the aluminum rod.
18. Now, it's time to set up the electronics. You need to create a circuit like the one shown in Fig. 7. Use the eight diodes and jumper wires to create this circuit on your breadboard, as shown in Fig. 8. The circuit will tell any electricity generated in each coil to go to the same place: the power column on the right side of the breadboard. Make sure all you diodes are facing the right direction, and don't forget to jump the ground columns across the board.
19. Notice the LED in the center and the two capacitors at the top and bottom of the board. Plug the long leg of your LED into the power column and the short one into ground. Before you add the capacitors, give the wind lantern a spin and watch the LED flicker.
20. Try adding at least one capacitor as shown in Fig. 7. The negative marked side should go to ground, and the other to power. The capacitor will store energy while the wind lantern is creating it, and release energy when it is not. The resulting effect here is a smoother flicker on the LED. Try adding more LEDs and more capacitors uhntil you get a smooth glow when you spin the aluminum rod. In Fig. 9, diffuser paper was placed over the side of the lantern, and three LEDs and two capacitors were used to create a pleasing glow.
21. Now take it outside (Fig. 10). See if it works with real wind.