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Build your own Savonius VAWT (Vertical Axis Wind Turbine)

Picture of Build your own Savonius VAWT (Vertical Axis Wind Turbine)
Build a cheap VAWT from a broomstick, 4 bearings, 2 buckets and some pipe.
 
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Step 1: Get some 25mm ID / 50mm OD bearings

Picture of Get some 25mm ID / 50mm OD bearings
Go get at least 2, or ideally 4 ball bearings with a 25mm (1inch) inner diameter, and a 50mm (2 inch) outer diameter. I bought mine for aout 6 Australian Dollars each at my local bearings store.

Prise the side seals off and scoop out all the grease, then rinse the bearings out with some diesel or turpentine to make them spin easier, then pop the seals back in. They should spin easily now.

Head down to the hardware store and find a cheap broomstick handle that just fits inside the bearings. Dont worry if its a tight fit.

While you're at the store buy some 50mm (inner diameter) PVC tube and 2 large buckets (I found about 20 litres ideal).Also uy some long screws - I used plaster screws at least 50mm long.

Step 2: Make the shaft

Picture of Make the shaft
Cut the PVC tube to be slightly shorter than the room handle, and then cut if in half again.

Tap 2 bearings to be close to the center of the broom handle, then slide the 2 lengths of the PVC tube and tap it down so its a nice tight fit, then tap another bearing into each open end of the tube.

I also fitted an end cap to one of the tube ends, as well as a bell shaped fitting to keep the rain out (see picture). Screw the top piece to the broom handle in the center so its fixed to the broom handle. The broom handle has now become the center drive shaft.

Check out the video - you now have a free spinning drive shaft - I have a small piece of dowel I drilled into the bottom of the broom shaft to show rotation while clamped in the vise.

Step 3: Add the VAWT blades

Picture of Add the VAWT blades
Cut both buckets in half so you have 4 blades. It pays to have the dog check your work ;)

I used an electric saw and just held it there while gravity did all the work. You could use a handsaw easily.

Then use a holesaw to make a hole in the top of each half, so it will fit over the top of the broom handle sticking out of the top of the shaft.

Please be careful and take the time out to think at each stage - the author accepts no responsibility for sloppy planning!

Step 4: Add a blade

Picture of Add a blade
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Screw on half to the top of the shaft.

Add some screws down the side - by using thread on the screw you can the leave a gap between the blade and shaft as it increases efficiency.

Step 5: Add another blade

Picture of Add another blade
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Add another blade

Step 6: Add the other two blades

Picture of Add the other two blades
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Add the other 2 blades below, at 90 degrees to the first two. This gives a much smoother running, and a better chance of the blades facing the wind at startup.

Remember to cut 50mm holes in the top of each bucket half so they fit onto the center shaft.

You can drill small holes where the top 2 blades meet the bottom two, and tie the blade sets together with wire or cable ties. This really stiffens the whole strucure up nicely.

Step 7: Trial run

Picture of Trial run
You now have a nice lightweight turbine to bolt to something heavy. Unfortunately I had little wind for one of the videos - the unit goes great above 10 kilometers per hour but this short gust is the best I could get yesterday.

You can see from the little coloured toy windvane that even though there's no wind, it starts in the lightest of breezes. It has a truckload of torque too when the wind is aout 20 kilometers per hour.

In the second video I have added two large blades from large domestic garbage bins. I tried grasping the broom handle and stopping the centre shaft coming out the bottom - too much torque! Tonight I'll add the other two blades. With a much larger blade radius I should be able to pull a lot more watts off of it!

Step 8: Time to make some power

Picture of Time to make some power
I'll add a generator set soon. There's plenty on my workbench.

With the following assumptions:
m(air) = 1.2 kilos per cubic meter
area(frontal) = 0.7 square meters
windspeed = 5 meters per second (about 15 kph)

Then Watts = 0.5 x 1.2 x 0.7 x (53)
= 52.5 watts

However Savonius Vawts seldom do better than 30%, so I better find about a 20 to 50 watt DC motor somewhere to try it out.

Check back soon...
Does the removal of the grease effect the longevity of the bearings?
yes, it will greatly shorten the lifespan of the bearings and the removal of the seal will allow alot of dust and grime to get in. i would recomend keeping the grease in there, any additional friction caused by the grease will be small and easily overcome by the wind
obudho3 years ago
I would like to use such an equipment to pump water from the lake to a garden near by. Any person with good design on how to go about this
http://en.wikipedia.org/wiki/File:Waterladder_pump.JPG
sam D (author)  obudho3 years ago
Yes. Search "savonius pump" on Google.
obudho3 years ago
hi, can the equipment be used to pump water from a 10ft well?
ecoego4 years ago
any update or news? I'm curious how much power you are getting out of just one of these. What will you be powering?
sam D (author)  ecoego4 years ago
Hey there, I am now just moved my workshop to a 5m by 9m shed. Expect an update soon! I am going to build a little genset of about 10 watts. But you can check out my other vids on youtube - I have been playing with adaptive blades.
http://www.youtube.com/user/samdekok72
boricua175 years ago
does the bottom piece screw down to the broom too? also when you screw the blades on top those screws are short that way they don't touch the bearing? when you screw the blades on the side it doesn't go all way there?
boricua175 years ago
how long does the screws has to be for the side....
sam D (author)  boricua175 years ago
75mm (three inches) is a good size. take care.
mhkabir5 years ago
Good luck on the generator.PM me if you have any Qs about the generator.I have have designed a few wind mills using the higth power WindBlue alternators and have 2 DIY ones from scratch and am now currently working on a micro hydro power project. I'll Even design a template if you want!!But, any requests, please after 19th August!!(will be busy until then)Also I added your 'ible to Green DIY, my group.
nickjohnson6 years ago
those gaps between the boards in your workbench must drive you crazy!
sam D (author)  nickjohnson6 years ago
Really handy for punching out nails and holding stuff. At first I thought so too - but like most ikea things you just gotta work em out. Cheers!
nickjohnson6 years ago
I thought the whole point of the overlap between the two halves was that air would flow from one cup to the other. With that pvc pipe in the middle, you can't get any air flow.
sam D (author)  nickjohnson6 years ago
Hmm, not easy to see from the photos I'll admit - but there IS about a 50mm standoff on each due to not screwing the screws all the way in. Study the photos and read the text and you'll get it. You can make the gaps as large or small as you want by adjusting how far you plunge the screws in to the central mast. Let me know if its still confusing and I'll email you photos. SD
dustyplans6 years ago
I gotta Try this>>> did you ever settle on a generator???
sam D (author)  dustyplans6 years ago
I think i'm gonna direct drive a invention i've made for tumble drying clothes outside, rather than take electricity from it.

But if you went a little larger with the blades you'd easily drive one of these:
http://www.thebackshed.com/Windmill/WhatFP.asp
(LG nowsell an equivalent and the brand new spare is only 90 dollars australian!). Lots of other info on google:"Smartdive alternator" search.

Would love a pic if you build one!
FireBAT6 years ago
Just wondering- what do you think about using motorcycle headset roller bearings for the lower bearings? They have cylindrical rollers instead of balls, and should act as a thrust bearing. They're tough, and weather-resistant. They can be a bit expensive compared to standard bearings, though.
stubell6 years ago
how are you all viewing the movie?
I used gom-player. VLC works as well.
V-Man7377 years ago
Favorited.
dchall87 years ago
The reason you don't see more vertical turbines is the bottom bearing is hard to maintain. It gets dirty easily, needs lubrication and eventually replacement. The horizontal turbines are way above the dust zone and don't have the same forces acting on them. So...don't skimp on your lower bearing if you want this to last.
The trick would be to have a large and sturdy sealed bearing race, that is then placed inside the turbine... So the turbine has an overhang below the bearing, keeping way more dust off it...
sam D (author)  killerjackalope7 years ago
The bearings are fitted inside the tube, and still have their seals fitted. Thanks for the feedback though.
As long as they're strong enough to take the weight and are well supported you shouldn't have any troubles... Also get them for at least double normal operating speeds, in case of storms and gusting that should help save you the bother of repairing them or replacing them, plus they'll last a long time that way...
sam D (author)  dchall87 years ago
The lower bearing could easily have a thrust bearing substituted - but this unit weighs 9 kilograms all up - so the vertical thrust is radically different to a metal unit. Both the lower bearings should carry 50% of the vertical load each. You could add more bearings I guess. Also, note that the lower bearing is fully encased by the 50mm polytube, and still has its seal fitted.It would take about 10mins to change out however.
faroun7 years ago
Exccellent work, you kept it simple and most will love it. i was looking at the umbrella at first on your movie...lol.. keep working on it you will find ways to improove on it. great howtos and pictures. regards faroun
Nice work. This is a great way to get some extra electricity, by harnessing power from renewable resources such as the wind. Keep up the good work! 5/5 stars