Introduction: Build a Savonius VAWT to Make Electricity 2012 Update
Once upon a time, I wrote an instructable on this subject and it has changed my life. As things have progressed very slowly, to some it may have appeared that I fell off the planet. To those that know me, it has been a difficult and arduous but rewarding process. Here , I would like to again share a Do It Yourself version of the turbine that I hope will also help change the world. If this sounds idealistic, forgive me, I tend to be that way. :)
I want to thank everyone - over 100 commenters on my original project - for their input and knowledge as well as their questions that lead me further in my pursuit. Thanks Guys!
I will try to take an approach on this project where I will give steps first and explanations of why following. You will also be able to download, as I did on the original project, a pdf with the whole process. Most of the document is the original with additional information that was not in the original. http://www.spinpower.org/DIY/My_Savonius_DIY.php (This is php to force the download instead of trying to open in your browser.) My website is http://www.spinpower.org if that wasnt clear above. I also have the following website name pointed to the same place http://www.smart-turbine.com .
Step 1: Materials Tools and Safety
Specialty Item prices are what I paid and may change
Magnet wire – 780 feet of 24 AWG or twelve 65 foot spools of 24 AWG $22
16 Neodymium magnets - 1”x2”x ½” (I had to order 24 for the $150 price) $150
Rectifiers (one full bridge for each phase – I recommend 3) $6 ea
Plexiglass – ¼” thick sheet about 25”x7” $Free
Scrap at city or school maintenance base
Skate Bearings (you only need 2) $3 ea
Home Improvement Stores
Galvanized sheet metal squares 2”x2.5”x about 18 or 20 gage
Glue – not cyanoacrylate or any others with harsh solvents, but must be
very strong and weather resistant I used Gorilla Glue and Liquid Nails
small projects clear indoor outdoor as well as Liquid nails in a caulk gun
Thread Lock (not the permanent variety, but high strength for sure)
Extension cord – sacrificed for delivering power from turbine to charging location
Screws – must be weather resistant (I use the 2” plated drywall screws, they are easy)
Large washers – used with the above screws for attaching coils to VAWT platform
Pressure treated wood for base of structure (32”x32” area for base)
Rounds (24” diameter, 2 for a single tier or 3 for a two tier)
Stove Pipe (2x 6” diameter for a single tier or 4 for a two tier all 36” length)
Pipe Nipples (3x 36” for single tier or 5 for a two tier)
Pipe Nipples (2x 3” for top extension)
Pipe Couplers (2 for single tier or 4 for two tier)
Pipe Elbows (2)
Bolts (to fit in bearing about 3 or 4 inches long, get several but you only need 2)
Nuts (for bolts, get at least 6 to allow for adjustments – its cheaper than a second trip to the store)
Washers (Fender to fit over the bolts, get at least 6)
Weather Treatment – Polyurethane or outdoor grade paint
Ball Bearing (you may find that buying a childs magnet building kit at a Target is cheapest, you only need one, size not critical but about 1/4” diameter or bigger is good)
Guy Wires and accessories (you will have to tie this to the ground so it doesn't blow over or wiggle)
Separate from the power generator is the rest of the power plant:
Batteries to store and buffer power
Charge Controller for batteries
Inverter to make battery power 110 VAC
Transfer Switch to run Inverter power to a house
Router with narrow plunge bit to cut a channel or similar rotary cutting tool
Hand Planer or Belt Sander to true up the rounds
Drill for driving screws and the occasional hole
Drill bits, standard and one paddle style that is the diameter of your bearing
Hole Saw (this is to make a jig, size not critical but should be 2” or bigger)
Soldering Iron, Gun or Torch and solder
Welder - optional for heavy duty build which also requires a length of steel and 1/4x20 screws, a tap to match and some steel squares, about $15 of additional materials around here.
Snips for cutting galvanize squares
Strap or Rope to tie unit together while glue dries (you could weight it down)
Clamp not necessary but will make some things easier
Compass (to find center of rounds)
Markers (red and black preferred)
T-Square or other Straight Edge
Hammer (you never know with this one, something may need persuading)
Vise Grips (for steel upgrade, used to hold tap if you don't have a tap and die set)
This is a DIY project, as always, you take responsibility for your choices and actions. This is presented for you to learn from and potentially mimic in order to produce a working electricity generating wind turbine. Also, the power generated is dangerous. Please maintain a high level of respect for this machine. My current revision will directly light a 60 watt light bulb in a 6MPH gust of ... Oh wait, thats not so much a gust as it is a breeze. The power output is scary. Treat it like power from a wall outlet.
Always wear safety glasses, ear protection and take all precautions when working with tools and raw materials.
Step 2: What to Do First...
In short, make 3 wooden circles that will be the top, bottom and "hip" of the turbine.
I used plywood for this revision, the thick flooring grade stuff. One 4x8 sheet was more than enough. Using my Rotozip and a plexiglass guide that I made, I was able to make very nice and "true" circles.
Step 3: After the Circles... Step 2
Mark half circles that approach but do not overlap the edge of the circles. They need to align so that they form an "S" shape. Trace the half circle marks with a plunge router or Rotozip but limit the depth to about 1/2 inch. This will create a channel for the stove pipe or "sails" to set into.
Step 4: Step 3 ... Repeat Step 2 .. But Not Really
This may be complicated to show here, but imagine the top circle the shape of the groove is an "S" and the bottom which will be facing the top is the mirror image of an "S". The middle circle will be a mirror of an "S" on one side and an "S" on the other but also set at 90 degrees off from each other to make a squiggly + sign if you imagine it as transparent material. This is better covered in the PDF.
Step 5: Step 4 .. Dry Fit
Open the stove pipe and flex it so that it wants to be more like 1/2 of a 1ft circle. When the metal is more relaxed to the right shape, you can dry fit it into the grooves you cut in the circles. The notch in the photo below is only there for the purpose of illustrating how the sail penetrates the circles, you do not need to mimic this feature.
If the dry fit is good and you are able to apply the top and "hip" circles at the same time, you will want to verify the orientation of the bottom and "hip" next. If all is good and you have all of your orientations correct, it's time to glue.
Step 6: Step 5 Glue ... If There Is Any Doubt, Repeat Step 4
Fill the channel of either the top or bottom circle, not both, with construction adhesive. Insert the stove pipe. Find the mirror channel on the "hip" circle and fill it with construction adhesive and position it on the sails so that you have 1/2 of the rotor assembly together with the wet glue. Strap it and leave it to dry for at least 24 hours. You will be sorry if you try to do the second section and the first pulls apart, it's messy and ruins the quality of the bonding. This step uses a thick bead of glue which will take extra time to dry.
Step 7: Step 6 ... Glue the Second Section
Same as step 5 with the remaining section.... Wait another day for glue to dry.
Step 8: Step 7 ... Reinforcements
Drive screws through the metal and in to the wood circles in two locations on the connection point of each sail, a total of 16 screws. 1 inch screws are fine. The outer most edge, about 1/2 inch from the metal vertical edge is the most important point. At higher RPM, and high wind, the stresses at this location can start to peel the steel out of the channel. This extra step will help ensure your turbine can handle high speed winds and strong sudden gusts.
Step 9: Step 8 ... Look at What You Have Done :)
Take a step back and be proud you have come this far. Then, paint, paint, paint. Primer, UV sealant, the works. I can not emphasize enough how important this is for the turbines longevity. It may feel like a lot right now, but its much easier than having to bring the turbine in from the yard or wherever it is and strip it, re-finish and re-install it. Get it protected now and put that problem off for years. From my experience, I've painted mine several colors. Start with white. Camo, grassy, clouds and other fun stuff goes over white just fine. So again, start with white.
Step 10: Step 9 ... If You Havent Painted, Go Back to 8 and Paint
Decide which end will be the bottom. This is where you will need to mark at even spacing, 16 tick marks for the magnet positions. I found that gluing the magnets on with construction adhesive was a lot easier if I put a screw in the circle first, directly at the measurement marks. The magnet will stay at the location as it is attracted to the screw and this makes for easier gluing.
Caution: These magnets are tough. Be careful.
Mark the magnets with red and black or something so you know which way is which. It doesn't matter which is North or South, so I will refer to them as A and B. Just mark them while they are stacked so they are consistent as you glue them. Attach an "A" at every other measure mark and let them dry for no less than 24 hours. Next wearing thick gloves, attach a "B" at every remaining measure mark. Extra caution for this step, the blood blister I got through my leather work gloves was very painful. Wait another 24 hours and add a bead of construction adhesive along the edge of each magnet. Wait another 24 hours and add paint to the magnets. Seal this stuff good.
Step 11: Step 10 ... a Winding Jig
Make some kind of winding jig. I used a 5 inch circle saw to cut two circles in plexiglass. You can see the result here. I use them with a bolt and several nuts to create the jig. I can then load the jig in a drill for fast winding. Once I have a wound coil in the jig, I can loosen the nut to remove the coil.
Wrap with electrical tape immediately and set aside. Repeat the coil making process 16 times with about 50 to 65 feet of coil depending on AWG of 24 or 26.
Step 12: Make 16 Coil Mounts ...
This can be simple or ... not. What it does have to be is non magnetic. Wood or plastic is a good choice here. Whatever platform your turbine will rotate above needs to support the coil holders nicely. I ended up with a simple 2x4 block that I mount to the platform with stainless steel screws. The minimal magnetic properties of the stainless are perfectly acceptable. You can also use plexiglass or left over plywood as shown.
Step 13: Be Creative and Build a Frame
You will need a simple frame to hold everything. You will also need to support the rotor with some type of bearing. See my diagram below for an early prototype arrangement that I used for experimenting.
Step 14: Connecting the Wire Coils ...
This is the step that gets people into the most trouble... it doesn't have to be complicated but it just doesn't seem to travel very well. All coils should be made the same way and all common fronts should face the same way (toward the center of the rotor or all away from the center of the rotor). When mounted properly, this allows for easy single phase wiring as follows:
Edge of coil A to edge of coil B - Center of coil B to center of coil C - Edge of coil C to edge of coil D - Center of coil D to center of coil E, etc...
Leave only the very first and very last wire open or un-connected, this will be where you hook up a diode or rectifier.
NOTE: DO NOT MAKE THESE CONNECTIONS WHILE THE ROTOR IS SPINNING, THERE IS POTENTIAL FOR ELECTRIC SHOCK.
Step 15: Whats a Diode or Rectifier
In overly simple terms, a diode is a "one way gate" for electrons. A set of 4 diodes is like a lighted intersection that organizes all of the cars so that the flow of traffic is all diverted on to a one way street. This effect is turning AC into DC current. The DC current can be routed through a charge controller and into a battery for storage.
Step 16: Thats It for the Basic Build...
again, you can download the PDF for a lot more detail and research information. You can visit my website for information about the commercial version of the turbine. I hope you find this collection of information helpful.