# home made windmill questions



## gobug (Dec 10, 2003)

Some time ago I saw a website with plans on how to make a windmill using some old bicycle parts and a DC servo motor. That has been in the back of my mind for a while and I recently decided to start working on making such a windmill.

The bicycle part is easy. The question I have relates to the servo motor. I can select different sizes and don't know what is best. I believe such a motor can be burned out if the speed it turns is too quick. I also think the amount of voltage and amperage it delivers is influenced by the speed the windmill turns.

A small motor is rated at 30 volts. There are many sizes, but the only other two I found were sixty and 72 volts. The biggest motor has replaceable brushes. The smaller ones are not replaceable.

I appreciate any help.
Thanks
Gary


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## strider3700 (Feb 2, 2007)

You're looking for a motor that produces the most voltage at the lowest RPMs and has the highest current rating. a balance of all 3 things isn't the easiest. 

I'm not sure what you're using the bike parts for. To gear it up in the end?

I've never used a servo motor I just use a regular dc motor. Look for either DC treadmill motors they come around 90 volts or if you can find them Ametek motors are old computer tape drive motors they are all over the place voltage wise. the 99 volt ones are the best but they are in demand for this purpose and are either impossible to find or expensive. 

To direct drive the motor no gearing involved you need it to produce about 1 volt for every 25 rpm. the ametek I have is 1 for every 35 and I'm currently gearing it up. It only produces currently in winds over 70 km/h 

Find you generator/motor first and then build around that. If you have anymore questions just let me know


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## gobug (Dec 10, 2003)

Thanks Strider,

The motors I was looking at were Ametek and they had been in a computer tape drive.

The bicycle parts will be both wheels. I will connect the hubs so the shafts are in line. Between the two wheels I will attach 4 one gallon paint cans cut in half to form 8 half cylinders. The half paint cans will have the cut pointing to the center of the hub. It will slightly resemble a ferris wheel. The center shaft will be vertical instead of horizontal though.

The bicycle gear on the rear wheel will be on the bottom of the "ferris wheel" and a bicycle gear will be on the motor shaft. A bicycle chain will connect motor to the "ferris wheel". If I make the motor mount adjustable I will be able to change gears to adjust the speed of rotation.

I am guessing that the larger motor requires more torque to spin the shaft. Since I haven't assembled my first effort yet I don't know how fast the "ferris wheel" will spin on my mountain property. Although I do have a weather station with a wind gauge, I cannot collect the data since I cannot power my computer there yet. Steady breezes are common, and wind gusts can be frequent and strong.

Is there a way to know how much torque is required to turn each motor?

Based on your comments, I might just get the 72 volt. It also has the brushes accessible on the motor whereas the other smaller motors do not have the same access.

Thanks for your response.
Gary


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## strider3700 (Feb 2, 2007)

That sounds like a lot of work to build a slow spinning high torque turbine. Power generation usually comes from spinning it fast rather then a slow spin geared up.

I did something similar to this.
http://www.mdpub.com/Wind_Turbine/index.html
Pretty easy


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## rzrubek (May 13, 2004)

gobug, you need to go here http://www.fieldlines.com/section/wind
Everything you want to know about building your own windmill is here.


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## justmyluk (Apr 28, 2005)

The best Ametek motors for wind generators are the 99 volt and the 30 volt(I have the 30 volt). The others (I've heard) require to many RPM's to produce 12 volts. My 30 volt Ametek motor starts producing voltage as soon as the blades start turning (just a slight breeze). 12 volts is reached at about 325 RPM's. Mine is only put up 20 feet on 1 inch schedule #40 pipe and has withstood 60 MPH winds with no problems. I think the wind zone maps are highley overated. I live in wind zone 1 (whch is poor wind speed) and my small wind generator will produce 12 volts for extended periods 6 days out of 7. IMO you need to look for a 30 volt Ametek motor to start with and get your feet wet. The 30 volt motor is also brushless so you don't have to worry about brushes wearing out. Just put it up and forget it... Go to ebay and type in "Wind Generator". You'll get a lot of ideas.


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## InkSlinger (Apr 19, 2007)

How do you get a servo to produce power instead of using it to spin??
Inkslinger


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## strider3700 (Feb 2, 2007)

When you spin a permanent magnet motor it produces electricity. To prevent the batteries from spinning the motor you put a diode in that stops current from flowing from the battery to the motor. Then when you turn the motor current flows through the diode into the battery. Basically the diode acts as a one way valve.


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## TechGuy (Oct 25, 2006)

gobug said:


> Some time ago I saw a website with plans on how to make a windmill using some old bicycle parts and a DC servo motor. That has been in the back of my mind for a while and I recently decided to start working on making such a windmill.
> 
> The bicycle part is easy. The question I have relates to the servo motor. I can select different sizes and don't know what is best. I believe such a motor can be burned out if the speed it turns is too quick. I also think the amount of voltage and amperage it delivers is influenced by the speed the windmill turns.
> 
> ...


As far as a generator, I would look at using a alternator. These are designed to operate a variable speeds since engines can operate a low or high rpms. Ideally it would be better to use a alternator that operates at a high voltage. I believe you can find alternators with output voltages as high as 48VDC. 

I believe commerically produced windmills have variable pitched blades so that the bladed don't spin excessively fast under high wind and low output loads. If the blades are attached using a bearing so they can rotate, a simple spring could be used to make the blade pitch variable. Ideally, an agressive pitch would be used during low speed wind, and a shallow pitch under high wind loads.

I think the most difficult challenges that you'll face is balancing the blades with a wind efficient shape. For strength they'll need to have a thick round cynrical shape at the base and a skinny flat edge at the other end (Like an aerodynamic rowing boat oar). A CNC Lathe would be the best option to make nice balanced efficient blades.

The next challenge is transporting the current from the generator head into your system. If you use a low voltage generator head, it will lose a lot of power if there is a significant distance between your windmill and your power system. You may need to step up the voltage to transport it efficiently.


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## Jim-mi (May 15, 2002)

Here is a very good paperback book from a very highly respected windy guy---Hugh Piggot.
--Windpower Workshop--- . .155pp $15.95
included is a design and build from scrap and recycled parts turbine.

Do it your selfer's can't go wrong getting this book.

you can get this book thru the-- www.the-mrea.org -- 
marketplace


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## Mr.Hoppes (Sep 30, 2006)

I wonder if a sump pump motor would work? I have seen them do some amazing things. I need to go to the HW stoare.. Later folks


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## SolarGary (Sep 8, 2005)

Hi,

The 4th one down in this section starting "How I home ..." is an article that has some info on building a small wind turbine with an Ametek motor, and on selecting the right Ametek:

http://www.builditsolar.com/Projects/Wind/wind.htm#DIYWind

It also has very detailed picture plans on making the parts and assembling it.

There are some other good make your own turbine sites listed on the same page.

Gary


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