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7 Foot Axial Flux Wind Turbineby brokengun on January 17, 2009

Table of Contents

7 Foot Axial Flux Wind Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro:   7 Foot Axial Flux Wind Turbine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 1:   Deciding on Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 2:   Modifying the Strut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 3:   Rotor and Stator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 4:   Magnets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 5:   Tail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 6:   Blades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Step 7:   Tower and Yaw Bearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Step 8:   Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Step 9:   Testing Jig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Step 10:   Generator Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Step 11:   Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Step 12:   Guy Anchors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Step 13:   Guy Wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Step 14:   Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Step 15:   Tower and Electrical Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Step 16:   Excuse me while I kiss the sky . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Step 17:   Finish up the wiring and test it all out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

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Intro:  7 Foot Axial Flux Wind TurbineThis instructable documents the process of my single rotor wind turbine. It is built with inspiration from Hugh Piggot and the folks at Otherpower.com. This is my firstattempt at building a wind turbine, and I will try to include the mistakes I've made along the way so that other first-time builders can avoid them! Since this entire projecthas a budget of just about $1000, it is meant to be able to be completed by both newcomers to wind energy as well as those who don't have a lot of money to throwaround. I also tried to use as much recycled material as possible, so a large portion of this turbine is made from a junked car and metal that was going to be thrown outby fabricators.

When I first began this project I had a decent grasp of electricity and electronics, which was helpful. I knew hardly anything about wind turbine design, but picked it upquickly with the use of several books and websites.

The books and works that have been most influential in the building of this wind turbine include:-Windpower Workshop by Hugh Piggot-Windpower by Paul Gipe-Arc Welding Instructions for the Beginner by The James F. Lincoln Arc Welding Foundation-Otherpower.com as well as many helpful individuals on the Otherpower forums

If you want to know more about electricity or electronics, the book Teaching Yourself Electricity and Electronics by Stan Gibilisco is a great learning book and valuableresource to have around.

Here is a video of the final project.

(The whole thing about the modern day Don Quixote... yeah, I don't think it's right either.)

Image Notes1. Too big

Step 1: Deciding on SizeSince this is my first wind project, I decided to work on something that is a bit easier to construct than a high-output "dual rotor" design. I also didn't have a lot of metalfabrication shops available to me, so I was looking for something that required little fabrication.

A Volvo brake rotor has become popular among homebrew windpower enthusiasts because of its wide availability and its relative ease of modification. Volvos have areputation for being long lasting and their rotors are not much different. A trip to the junkyard landed me with a $20 Volvo 340 strut (rotor, spring, and everything).

A single rotor design only has one set of magnets that spin in front of a stator coil. This makes construction easier and less dangerous, since you don't have to use"jacking screws" to bring together two magnetic disks. This is dangerous because if you slip, you could very well break your hand or finger. With a single rotor design,there is much less chance of this.

One thing that many people don't realize about wind turbines is that the blades of a particular turbine are matched to its generator. This is all based on what is called "TipSpeed Ratio" or TSR. By matching the correct blade diameter to your generator, you ensure that the turbine will start generating at a certain wind speed. By having theright size blades and generator, the correct RPM and torque will be produced to generate the maximum amount of power safely (that is without overheating or over-speeding the turbine). Matching the blades to the generator is a very important aspect of designing your windmill, and many other aspects of the machine are based onthe blade diameter.

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For this particular design the blade diameter should be around 7 feet.

Step 2: Modifying the StrutMost homebrew wind turbines are designed to mechanically turn out of high winds. This is called "furling" and is very important to protect the wind turbine in high winds.Do not underestimate the amount of power in a strong gust of wind, as it can seriously damage a wind machine. To have the turbine turn out of the wind, the generatorand blades are mounted off to the side of a yaw bearing. We mounted our generator about 6 inches away from the center. This is overkill for this size generator, but we'llbe playing it safe as this will cause the machine to furl earlier.

In addition to mounting the generator at an offset, the tail will be mounted to specification to allow the generator to turn while the tail stays straight.

We removed the spring and the inner cylinder of the Volvo strut with a cutting torch. We also removed the rotor (to be modified later) and the piece of metal behind it.Then, the remaining piece of the strut was cut in half and welded onto the side. We also added a piece of metal to give another place to attach the stator to.

Image Notes1. Extra piece we added2. We removed the bearing too3. Extra clean work environment ... yeah right.

Image Notes1. Fishmouth the piece to weld it on securely.2. This is special fireproof fabric to cover flammable or fragile things while youweld

Step 3: Rotor and StatorOne of the more technically challenging and labor intensive parts of building a wind turbine is winding and casting a stator coil. A very thorough knowledge of permanentmagnet generators is needed to calculate how to wind an optimal stator. If you are determined to do it, you can simply follow the example of someone else's successfulgenerator. Again, this being my first shot at windpower, I didn't want to risk winding the wrong thing, messing up the wiring, or ruining the casting, so I bought one fromOtherpower.com. They make lots of different stators for a variety of magnets (rectangular and round) and voltages. Most axial flux wind turbines use a three phase statorfor more efficient generation.

Since this is a single rotor design (stators on Otherpower are usually made for dual rotors) we will only be generating half the stated voltage. So, for this project I wanted12 volts and had to buy a 24 volt stator. Otherpower actually is now offering a kit for a single rotor wind turbine that is pretty much the same as this one. It's still cheaperto fabricate your own, though.

The stator is made for a 12 inch rotor, but the Volvo brake rotor is only 10 inches. So, we were forced to add on to the outside edge. This was probably not the bestsolution, but it should work fine. I would recommend getting a 12 inch steel disk from a CNC water jet if possible, which would be a lot cleaner and provide a bettersurface to mount blades.

We used a piece of 1/2 inch plywood mounted to the strut and then mounted the stator to the plywood. Make sure there is clearance for the stator coil to clear the wheel

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bearing.

Image Notes1. A lot of time goes into winding those coils!2. 3-Phase AC

Image Notes1. 12 inch circle

Image Notes1. Not perfectly round on the outside, but it will do

Image Notes1. These bolts will actually be on the other side when mounted.

Step 4: MagnetsI used twelve 1 x 2 x 0.5 inch rectangular magnets from Magnet4less.com (very reasonable prices). On the back of the rotor, I also used an aluminum plate to keep themagnets separated (this plate is also available from Otherpower). We used heavy duty epoxy to ensure that the magnets won't fly off at high RPMs. Be VERY carefulwhen you put these magnets into place - they have enough power to severely injure or break your fingers! I found that a little caution and a rubber hammer wereinvaluable tools.

The magnets are placed in alternating polarities on the back of the rotor. We used a small magnet to test each magnet's polarity.

I left the magnets exposed, but I am planning on a possible renovation soon. I should've cast the magnets in some sort of resin to prevent corrosion. There is plenty ofgood information on the internet on how to do this, and it's very similar to casting a stator coil.

Once all the magnets are on the rotor, remember that the whole disk is now one gigantic magnet. Do not set it on a workbench with metal shavings or magnet-sensitivematerials!

Also, you may notice that the pictures are a bit out of order (the rotor is painted already) but I am trying to lay this out in the most logical order... not necessarily the orderwe did it in!

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Image Notes1. They are kind enough to put small plastic spacers in between these bad boys

Image Notes1. mounted aluminum plate

Image Notes1. Lots of magnets2. Heavy Duty Epoxy

Step 5: TailThe area of the tail vane and the length of the tail boom are both dependent on the diameter of the windmill. This ensures that furling takes place at the right wind speed.The tail boom should generally be about as long as the radius of the turbine (one blade length). In this case, it should be around 3.5 feet. In reality we made it quite a bitlonger by mistake. It still seems to find the wind alright, but I think it will effect furling.

As for the area of the tail vane, it can be determined by a simple equation: D(squared) / 40 = Area of the Tail Vane (where D is the diameter in your unit of choice). Thisequation is given by Hugh Piggot who has many years of small wind turbine experience.

The shape of the tail vane really has very little effect on the mill as long as the area is correct, so feel free to get creative. I spent some time with an air grinder and cut outa neat looking tail, but it's not entirely necessary. What does matter is the angle at which the tail is mounted. It needs to be at about 45 degrees from directly behind thecenter post on the opposite side of the generator. In addition to that, it should be mounted at a 20 degree angle from perpendicular - the pictures I've included illustratethis nicely. This may need to be adjusted slightly depending on when you want to mill to furl and how heavy the tail vane is.

The tail is made of electrical tubing and brazed together. We put a lot of supporting pieces in the middle of it to strengthen it. The tail vane is made of stainless steel and itis riveted onto the tubing.

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Image Notes1. Rivets

Image Notes1. Bolt fits nicely through the tubing

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Image Notes1. Weld isn't finished yet in this picture2. Good angle3. Harley-Davidson... oh yeah

Image Notes1. Lots of brazing to add support

Step 6: BladesPersonally, I am not a very good carpenter. My woodworking skills are pretty basic and making your own blades requires some pretty good attention to detail. So Idecided to save myself the time and effort of making blades and just buy a ready made set.

There are lots of guides and tutorials for blade-making online. Hugh Piggot even offers a nice table of useful figures for different blade diameters in Windpower Workshop.

Now, there is a lot to consider when buying blades. First and foremost, consider the power you are taking from the wind. This is based mostly on the diameter of yourwind turbine blades. A wind turbine steals energy from the wind by slowing it down as it passes through the blades and makes the rotor turn. This is all laid outmathematically by the Betz' Limit . These calculations show the maximum amount of energy that is possible to be extracted from the wind, though they do not account forlosses in generator efficiency... they also assume that you have infinite blades which all have no drag, and if you can hook me up with some of that, I'd be very interested:).

It isn't so simple as bigger blades equals more power, though! No, no, no. What is most important is that you match the blades to your generator. Generators aredesigned to start producing usable electricity (the voltage you want) at a certain RPM. This is where the Tip Speed Ratio comes in. Basically, you want to have bladesthat provide that RPM at the most typical wind speed you'll be experiencing. Sound complicated? It is, kind of. Usually the Tip Speed Ratio (TSR) is an indicator ofefficiency, but beware of websites claiming abnormally high TSR's! I would recommend using it as a rule of thumb.

There really is a lot to blade making as well as blade theory, but that should give you some good general insight into what you're trying to accomplish. As for me, I boughtmy blades from a website called Magnet4less (no 's'). At first I actually bought the wrong size blades thinking I could get away with a bigger diameter, but alas, physicswins again (Some of the pictures may have these first blades in them). I eventually folded and bought the 6.8 ft. diameter blades. However, I would NOT recommendbuying these blades again. They have terrible reviews from wind power people around the country and with my personal experience they look like the angle of attack justisn't enough to spin up high RPMs.

This is the part where I suggest another retailer but, to tell you the truth, I really don't know of one. Homebrew wind turbines enthusiasts seem to be mostly (but I could becorrected) out of luck for high quality universal blades with different diameters. I suppose you could use a pair of replacement blades from another commercial turbineassuming they are to your needs.

Other references!

For making wooden blades:http://otherpower.com/blades.htmlhttp://www.thebackshed.com/Windmill/PropellerBlades.asphttp://www.mindchallenger.com/wind/wgpage15.html

If you're interested in making blades out of PVC, I'd recommend using Google for instructions. I don't recommend PVC blades for a turbine like mine, though.

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Image Notes1. Wind turbine crash landing on a messy work bench

Image Notes1. Note how the blade and tail boom are just about the same length

Image Notes1. Mounting and fitting the blades, separating them perfectly was very tough.

Image Notes1. These were the old blades, the turbine isn't as large now.2. Awesome Grandfather3. Pride and Joy

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Step 7: Tower and Yaw BearingNow that most of the construction of the actual wind turbine piece is complete, you'll have to decide on a place to put the beast! Obviously a good spot with lots of windand few obstructions is optimal. Most DIY wind power enthusiasts recommend that your tower be 30 feet above the nearest obstruction within a 300 foot radius. In otherwords, pretty much as high and in the most open area as you can get it.

Selecting a location and tower is difficult, there is no doubt about it. It's hard on your wallet and your time. The biggest concern when putting up a tower should always besafety. This is a homebrew turbine and could run into problems that we can't quite predict, so a little extra safety is always good. Be aware that if your blades fail at highRPMs if they will fly quite a distance and could pose a threat to nearby houses or cars.

A basic run down of the tower options available.

-Monopole towerNo guy wires, requires a lot of concrete and are almost always very expensive.-Tilt down pipe or lattice towerUsed by the majority of the DIY Wind Power community because of cost and ability to tilt the machine down for maintenance. Uses guy wires and a hinge at the bottom ofthe tower and can be welded together with the correct pipe.-Lattice towerAnother choice is to construct a lattice that does not tilt down but still has guy wires. The problem with this is that it must be climbed to do anything to the windmill. Manypeople do not feel safe doing this and many people have been hurt from falling off stationary towers like this. Use extreme caution and a safety harness to work on top ofone of these towers.

I was fortunate enough to receive a free 30 foot lattice tower from an airport. It was once used for a rotating beacon and should be strong enough for my small windturbine. I had to add to the top of it (about 5 feet) to attach the wind turbine with enough clearance for the blades to move around when the machine furls. For support, wewelded gussets onto a piece of 2 inch pipe and attached it to the top of the tower.

Then I took a piece of schedule 80 pipe to a machine shop and had it turned down on the lathe so it would act nicely as the yaw bearing. We leveled it on the tower andplaced some set screws in so it could be welded in place. This piece is important because, if it comes loose, the whole turbine could fall off or the blades could hit thetower! YIKES!

Welding was completed with a DC arc welder. I'm still not terrific at welding by any means, but it's a great skill to learn. Before I made the welds on the tower, I did somepracticing on some scrap pieces I acquired from a metal shop. That's another thing you find while trying to learn to weld - people in metal shops are usually quite friendlyand willing to help out. If you're thinking about learning but are lacking material to practice on, ask around - what many might consider junk could be very useful to you.

Image Notes1. Excitement!2. 1 of the 3 ten foot sections

Image Notes1. pile of speedy dry2. The addition is bolted to the top plate here.

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Image Notes1. Tacked in place2. The gussets aren't the same size but we think it should be plenty of support

Image Notes1. Right on the mark2. Clutter

Image Notes1. The welding gods are clearly smiling...2. Discarded air cleaners from heavy equipment make excellent garage stools

Image Notes1. Hey, it's practice! It doesn't have to be useful afterwards! C'mon though, whodoesn't need a mediocrely welded almost trapezoid...

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Step 8: ControllerAt first I was going to build my own controller, as I have shown in the pictures below. The project shifted locations, though, and I decided to charge a battery instead ofheat water, so I decided against it. I did have a rough idea of what I was going to do, but I think not making the controller on my first turbine was probably a good decision.Things can get dangerous if your controller fails and lets your turbine run away at reckless RPMs. Also, believe it or not, electrical permits prefer stuff that's UL listed...who'd have thought that?

Instead of heating water, I decided to charge a 12 volt battery that would be hooked up to a light. This cut down on costs, logistics, and other restrictions that made it a biteasier to install. I settled on using two Xantrex C40 charge/dump controllers. One regulates the charge coming in and the other watches the charge level of the battery toensure it is not overcharged (it can't do both at the same time). I have a 12 volt dump load that is a water heating element, rated for 600 watts.

I used a three phase disconnect switch as the "brake" on the wind turbine. When the switch is closed, all three phases of the wind turbine are shorted out and it will slowitself down. I also used a 750 watt modified sine wave inverter to run the light. The light has a photoelectric eye on it and is wired up to turn on at night.

Image Notes1. Homework or something

Image Notes1. This... yeah this is important

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Image Notes1. Optima lead acid battery, 65 ah, 12v

Image Notes1. Three phase disconnect

Image Notes1. Battery goes here2. Charge controller3. Dump load controller4. 750 Watt Inverter5. Rectifier

Image Notes1. USB Programmable!2. Resistors3. Trusty iBook G44. Freeduino5. Serial LCD and Board6. Test voltage

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Image Notes1. Learning to use the LCD

Step 9: Testing JigBefore programming the controller, it is important to see what kind of power output you can achieve with your generator. This will help you determine what RPM is optimalfor you to run at and how that affects the pitch of the blades.

Now, a lot of people have a lathe, a tachometer and a bunch of other fancy tools to test their generators. Well, I am a bit less fortunate and do not have those available tome. So, instead, I made a simple jig to spin up my generator using an electric drill.

I cut a notch in a small piece of wood and shaped it as a trapezoid to avoid all the holes for the bolts. On the other side, I screwed through a hole in the metal into thewood to hold it in place. The other two planned attachment places were too close to the edge to take a screw, so I drilled a couple of small holes and used small zip-ties.Surprisingly, this setup is pretty solid. The piece of wood doesn't act like it's going anywhere and those zip-ties are nice and snug.

Now, with all of these funny angles and stuff, it's hard to find the exact center of the rotor. I did the best I could to eyeball it and I drilled two more long screws partway intothe wood on either side of the center. Then use an allen wrench with a T-handle on it that is long enough to touch these two screws. These screws will take the torquefrom the drill to spin up the generator.

Image Notes1. Testing jig mounted.

Image Notes1. Zip-ties are saviors.

Image Notes1. Camera timer fail.2. Jig.3. Wind generator4. I think this is some high voltage power supply

Image Notes1. This allows the drill to be adjusted slightly to find a better center. It works alrightfor such a cheap setup.

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Step 10: Generator TestingTo gather data on the output of the generator, you'll need a few things. Mainly a couple of good multimeters, a test load, and some way to read the RPM.

I attempted to use the equipment in my physics lab and Datastudio to measure the frequency of the AC current, then I tried to work backwards to figure out the RPM ofthe generator. If I remember correctly, I had to divide by 6 to get the RPMs. This method, however... was extremely inaccurate. I kept getting readings that were very off.Despite the pretty graphs the equipment was generating, I would not recommend trying to use this method for measuring RPM.

Many people use fancy bicycle tachometers with good results. Some bicycle tachometers can be found for under $20. Luckily my physics teacher is an avid bicycle riderand had a box full of old bicycle computers that he let me try out. I found one with an RPM counter and zip tied a neodymium magnet onto one side of the testing jig.Then I used a ring stand and a clamp to hold the sensor in place. Now I could read the RPMs fairly easily, although they didn't update immediately this method was farmore accurate. I would highly suggest if you want accurate readings to get a decent tachometer or a bicycle computer with an RPM setting.

I was also able to use Datastudio to measure the DC voltage coming off the generator. The equipment only measured up to 10 volts DC, so I used a simple voltagedivider to scale down the voltage being read by the computer. This allowed the computer to read 1/12 the voltage being produced. So the actual voltage on the graph was12 times voltage read by the computer. See pictures for the schematic. The voltage across R2 should be 1/12 the voltage of the generator, this is shown in the graph.

Also, I needed to flatten out the DC coming off the rectifier. To do this I used a big capacitor in parallel to flatten out the voltage spikes, giving a more accurate DC voltagereading. You have to watch a lot of things when you spin up the generator. It's hardest to measure voltage, current and rpm while still holding onto the drill.

For my test load, I used six 18 ohm 25 watt resistors in parallel for a total of 3.6 ohms.

Image Notes1. Physics lab equipment2. Big capacitor

Image Notes1. Test load2. Sketchy wiring

Image Notes1. Voltage spikes2. Actually 7.2 volts without the voltage divider

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

Image Notes1. Voltage from rectifier2. From the rectifier3. Connected to the lab equipment

Step 11: BaseSince my tower was 36 feet tall and in a triangular lattice structure (18 inches per side), I knew I would need a big sono tube to support it. After googling, reading, andasking a certified wind turbine installer, I settled on a 2 foot diameter, 6 foot tall sono tube. It's not a bad idea to consider the soil you'll be digging into, as some placesmay need more of a footing just to be sure.

Luckily for me, since this project was being funded, we were able to talk the local concrete place into doing it all for free. They even dug a hole and centered a piece ofpipe in the casing for us.

Also, consider how you want to attach your tower to the base. My first thought was to have tree bolts sticking up from the base (one for each leg), but the wind turbineinstaller suggested something different. He suggested we put a piece of plate or something on the bottom with a hole in it, then have one solid pipe or piece of bar stockin the base and slide the tower down over. This does a couple of things. Firstly, it allows the tower to move, which is nice, and secondly, it reduces stress on the concretebase because the pipe is centered on the casting.

Image Notes1. Awesome Aroostook County dude2. Big hole3. 2 ft diameter, 6 feet into the ground

Image Notes1. Glad I didn't have to dig this hole by hand!

Step 12: Guy AnchorsI decided to use three guy anchors, one for each corner of the tower. These anchors should be evenly spaced and as close to equidistant from the tower as you can get. Ichose a 22 foot guy radius, meaning the distance from the center of the base to the guy anchor hook was 22 feet. This figure was based off of some other towers I hadread about as well as the suggestion of the wind turbine installer.

It's a good idea to get a friend to help you put in the anchors, since pouring concrete by yourself isn't much fun. The anchors we used were 4 foot long screw anchors (butwe didn't actually screw them in). The backhoe dug the holes and then we put in the anchors with concrete. I screwed the anchors in slightly to keep them in place whilewe poured the concrete. I used four 80lb bags of quickcrete in each hole. This was simply an estimation; I know very little about concrete and felt this was plenty (and Iam pretty sure it was). I let the quickcrete dry and then backfilled the holes. It is a good idea to let the concrete settle for at least a day before backfilling the holes.

Image Notes Image Notes

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1. You know what? Concrete is heavy... it just is. 1. Time to backfill the hole.

Image Notes1. Guy wires all attached2. 4 bags of concrete

Step 13: Guy WireThe guy wire we used was second-hand from a local telephone pole installer. It's the same stuff you see guying down telephone polls all over the place. I think it'stechnically 3/16th of an inch thick, but I'm not certain. The wire is overkill for my tower, but we got it for free so I figured it's better to be safe. We didn't use traditionalcable ties on the wire. It came with a bunch of twist hook pieces that wrapped around the wire and then twisted on. They were made to work specifically with this size andtype of cable. Look at the pictures to get a better idea of what I used.

The tower is guyed at 6 places, three wires at 20 feet and then 3 more at 30 feet.

If this is your first time putting up a tower like this, it is nice to have someone around who has done it before. A lineman from Central Maine Power was able to help erectthe tower and rig the guy wires on the day on installation. It was tremendously helpful to have someone with experience.

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

Image Notes1. Typical telephone pole guy wire

Image Notes1. These twist around the end of the wire and are surprisingly strong. They form aneye so you can connect them to ground anchors.

Step 14: AssemblyBefore you get too trigger happy, assemble the turbine on the ground once more before you raise it. Check to see if the tail will run into the blades, if the blades are tooclose to the tower, if the rotor and blades are balanced and anything else that might not look quite right.

I assembled the whole turbine in the garage and made sure my tail wouldn't hit the blades by adding two 3 inch bolts that will stop the tail if it whips around. This has notbeen a problem, though, since most of the tail movement is very slow and gentle, but you never know when you'll get a tremendous gust of wind.

Make sure the top of the wire is water proof and the electrical connections are solid.

Image Notes1. Too big

Step 15: Tower and Electrical WorkFor the type of tower I have, I decided it would be best to assemble it all on the ground and use a bucket truck to lift it up. Having a few friends around to help is a verygood idea and during the tower installation it helped a lot. We had 4 people working on preparing the tower. We all worked on different pieces, a couple of us put togetherthe tower, I bolted it together. We ran conduit and wire and attached one end of the guy wires to the tower while it was still on the ground. This saved a lot of time andgave us a lot of eyes for when the tower was in the air.

We had to be careful to leave enough wire at the top of the tower to allow the turbine to yaw back and forth. I've read that wind turbines rarely will do a 360 degree turn,but it's a good idea to allow enough slack just in case. All of this installation was performed to electrical code because we had the electrician on hand to help us.

We attached the guy wires to the tower before it was raised and set the generator on top. Since the generator just sits on top of the tower, the tower needs to be up at anangle while it's on the ground or it will slide off (hence the saw horses). I used some lithium grease we picked up at the hardware store to grease the yaw bearing and thetail bearing.

The third picture shows the top of the tower all rigged to the bucket truck (which you can't see) and ready to be lifted up.

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

Image Notes1. Valuable helpers2. Anger?

Image Notes1. Watch out to make sure this doesn't slide off2. Rigging

Step 16: Excuse me while I kiss the skyNow the tower is lifted and shifted into position. We lowered it down onto the base and attached the first set of guy wires. We then tightened them up with a come along,going evenly around the tower and ensuring that it was level. Once the guys were attached, it was time to attach the blades and tail. I was fortunate enough to get a ridein the bucket truck to do this. It could also be done with a safety harness and someone who wants to climb the tower, but it would take a bit longer and be a lot moretreacherous.

I made sure I had the electrical brake on while I assembled the turbine. The last thing I wanted was the machine to take off with only two blades attached! Luckily, theweather held out and it was a nice calm day. I was able to attach the blades and tail with no major problems.

Sadly, I have no pictures of the tower being put in place because I was too busy helping.

After everything was up, I drove a ground rod in the soil next to the tower and ran a piece of wire to the tower to electrically ground it. Driving a ground rod is hard work,luckily I had help. Then I covered the wire and ground rod with a bit of dirt to make it look better.

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

Image Notes1. Blades2. Excitement Image Notes

1. Cold galvanized paint

Step 17: Finish up the wiring and test it all outThis was a big project. Once everything is up you can sit back for a minute and relax. It is awfully satisfying to see your creation spin up in the wind. The first day I putmine up, I didn't see it spin at all, so don't get discouraged if you see no immediate results. It is often said that once you put up a wind turbine, there are two weeks ofdead calm weather afterwards.

Haven't gotten a chance to get any real power readings yet because the turbine is installed about 6 hours from where I live. I'll be making a trip up there soon though tomake some adjustments and hopefully get some data. I am shooting for around 500 watts (I've read of people with similar designs getting about that much). As long as Iget any usable power out of it, I'm happy. It's been a long project for me: I started constructing the turbine in July of 2008 and it got put up in May 2009.

I'd encourage anyone who is interested in wind power to do their own project, it will help you learn a lot and is very rewarding. The view from on top of the tower is anadded bonus.

Image Notes1. Happiness.

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

Image Notes1. A little windmill, next to a little boy.

Related Instructables

DIY 1000 wattwind turbine bysspence

FarounLenz v2 VerticalAxis WindTurbine byfaroun

How to Build aWind PowerGenerator(video) bydoctorgig

FarounSavonius WindTurbine byfaroun

HorizontalDouble HelixWind Turbine byUltra Computers

FAWT Silo. (vawt windturbine hawtsavonius )(Photos) byfaroun

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Comments

47 comments Add Comment

 kbooth23 says:  Oct 22, 2010. 3:48 PM  REPLYHey im loving this instructable, the wind turbine at my college got me interested in building my own. I thought this looked very do-able until i got to this step. Iwas wondering how much the controller and other parts in this step costed, and if it was difficult to assemble them all?

 brokengun says:  Oct 24, 2010. 6:51 PM  REPLYI can't remember exactly what I paid for them. I think it was in the range of $120 each. I bought two, but only ended up using one as the chargecontroller. I used a bridge rectifier and a schottky diode to rectify the three phase power coming off the turbine. The controllers weren't hard to hookupthe manual that comes with them is pretty good. There isn't any assembly required, just wiring the wind turbine up. I think I had to change the position ofa jumper and that's about it, there are small potentiometers to change when the dump load is turned on (by checking the battery voltage).

I've really gotta update this thing though. Currently the turbine is down for repairs, a weak spot just above the weld on the tail's hinge pin gave out. I planon redoing it almost entirely at some point but college has been keeping me busy.

If you've got any more questions, feel free to ask. One thing I can definitely say though is if you don't want to be constantly maintaining the machinemake sure you don't cut corners. Do it right, or do it twice.... sometimes you gotta learn the hard way, eh? Best of luck.

 bertzie says:  Jun 22, 2010. 2:30 AM  REPLYSo wait, do you spin the magnets or the wire coil?

 megapix says:  Oct 22, 2010. 7:04 PM  REPLYYou spin the magnets. That makes it easier to connect to the coils, since they are stationary.

 ThreeWestCreative says:  Apr 2, 2010. 6:17 AM  REPLYExcellent instructable! I'm thinking of building one of these for my home build project. But I was wondering, it would seem possible one could use the coretechnology (i.e. the magnet and coil assembly) and arrange for other ways to make it spin and generate electricity, no?  I was thinking, could I build that partand say use water power to spin it and make it generate electricity? Or find some other creative way to spin it.  :)  Thanks.

 brokengun says:  Apr 2, 2010. 6:02 PM  REPLY Sure, people build homebrew permanent magnet generators all the time for various applications. Wind, hydro, steam, human power, whatever. Justmake sure when you wind the coils to get the right gauge wire and the correct number of turns. This can take a bit of experimenting sometimes, but youcan also reference a lot of material online. 

Be sure to show us what you end up building, good luck!

 ThreeWestCreative says:  Apr 8, 2010. 10:22 AM  REPLYThat's great to know! Thanks. :) I'll be sure to document it and let you know. I will most likely work on something like this alone and don't think I'd beable to handle the pole creation and standing part alone but I could use this same technology for ground level electricity generation.

 mahesh.ganpate says:  Dec 27, 2009. 10:52 PM  REPLYva....v very nice please send deatails images and drawing for genereter rating details i m starting a new wind turbine 1 kw manufacturing by home made .then so pls help

 brokengun says:  Dec 28, 2009. 8:32 PM  REPLY If you would really like more details plans for the generator I would suggest visiting Hugh Piggot's website and purchasing his book "A wind turbinerecipe book". It's full of detailed plans and specs.  www.scoraigwind.com/books/books.htm

If you've got any specific questions I can do my best to answer them, if not the guys at www.fieldlines.com can probably help fill in any gaps. 

 mahesh.ganpate says:  Dec 31, 2009. 3:30 AM  REPLYthanks , for u r sugess but we wont to 1kw genereter making the basicaliy rating of genereter  and  iwas perchasing this wec book but there notspecifiy ingenereter rating ditails and wave deatials . i thk u r sugess me  .genereter details . india  here ueing the matric system . but book in site alldimanstion mph inch etc there  .

 brokengun says:  Dec 31, 2009. 11:36 AM  REPLY There are both metric and standard (english units) versions of the book available on that site. 

I think you want a more in depth analysis of the generator. Most homebrew wind power folks won't get that in depth. Basically Hugh's book wouldoutline which generator plans seem to work best partly through trial and error. 

I think to get the kind of detail you want, you might consider a different book with more mathematics. However that book might also depend on ifyou are making an axial flux or radial flux generator. 

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

 mahesh.ganpate says:  Jan 2, 2010. 5:41 AM  REPLYtx brokengun,

   i have agree with u u r coment  i have making  for axial flux genereter. but i don't know  which parameter using for generotor making,   only30 mtr tower bearing ,gue rope , tail van avalable  here  but  genertor details not avalable

 brokengun says:  Jan 3, 2010. 2:19 PM  REPLY I guess I am confused as to what parameter you want. The book I recommended specifies wire size, number of turns and the physicaldimensions of the coils and the casting. Basically everything is there. There is more information not included such as how much powerthat stator can handle but this can be roughly calculated depending on the resin used. 

The wiring of the coils is basically a matter of your application and preference (eg. star, wye, delta). 

 mahesh.ganpate says:  Jan 4, 2010. 6:58 AM  REPLYhow much price sir , book parchasing ,im not parchasised book

 mikeyeez says:  Jan 3, 2010. 1:23 PM  REPLYGreat job man bright future ahead.

 spylock says:  Dec 28, 2009. 7:53 PM  REPLYYou can buy a 400 watt wind turbine for about  $600.00 from the Sportsman's Guide,of course youve got to build or buy a tower,Theirs is 30' and about thesame cost is about the same cost.

 brokengun says:  Dec 28, 2009. 8:28 PM  REPLY The one in the Sportsman's Guide looks like an Air-X brand generator, although it doesn't say the brand on their site. The rotor diameter of that turbineis slightly smaller than mine. Also, I have heard a lot of complaints about the noise generated by the turbine's blades. 

Other than that I don't know much about that turbine in particular. I've seen a few around. It looks like there tower setup costs $650 as well as thegenerator. Don't forget the controls, wire, batteries, concrete, etc you might need. 

I will say it is definitely less work! 

 spylock says:  Dec 29, 2009. 6:51 PM  REPLYYea,I just figured Id through that out there,the tower they sell in my opinion is kinda over priced.Also I was going to make my own useing a RVgenerator,and use the old control panel and stuff out of the RV Im scrapping what would be your thoughts on that?

 brokengun says:  Dec 30, 2009. 6:08 PM  REPLYDo you mean the alternator that is hooked up to the RV's engine or a separate generator that produces electricity for the RV?

Car alternators charge at a very high RPM, much higher than most wind turbines so reaching charging RPM can be difficult or require gearing ofsome kind. 

Many people rewind the stator coils in an alternator with thinner wires to achieve higher voltages at lower RPM. It's a project and there is somefiguring involved depending on the dimensions of the alternator and what power output you want from the thing. 

 spylock says:  Dec 30, 2009. 7:28 PM  REPLYYes,They call them altenators now,but this is an old RV and its actually a generator,I was going to do a small diam. pully at the blades andrun a belt to get some higher RPMs at the generator ,and use the old breaker box,charge control and other stuff less the wire and recepticles.Ifigured Id run it to three deep cycle batteries,I just want to try something that will take care of my bedroom,computer,small lamp,ex. for whenwe lose power,sorry for the bad spelling by the way.

 Blackice504 says:  Sep 7, 2009. 6:02 AM  REPLYits a good and clean build but is this wind mill too heavy? i was thinking of making it out of fiber glass and really light weight stuff for the wind turbine.

 brokengun says:  Sep 7, 2009. 6:53 PM  REPLYThe machine is quite heavy, yes. However part of this is out of necessity. The rotor which is made of steel should be made from some ferrous material. Aferrous material is helpful for the efficiency of this alternator. I think it has to do with improving flux and essentially turning the entire rotor into a bigmagnet. However the back pieces could be made some something else I guess. There is a lot of stress on those part though. The bearing and nacelleput up with a lot of bad weather and harsh wind so I would rather have something with some heft. The other place to save weight would be with the tail.As far as that goes, I don't think you would save much weight compared with what I did. The electrical tubing used was very lightweight and the 1/8 inchstainless steel that the vane was cut out of is also pretty light. If you do end up making some of the pieces shown here out of fiberglass, I would like tohear how they hold up.

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

 Blackice504 says:  Sep 7, 2009. 6:15 AM  REPLYlove the tower install great job

 brokengun says:  Aug 19, 2009. 11:31 AM  REPLYBasically yeah... we had to expand on the 10 inch rotor to make it fit the stator coil that I ordered. However if you're good you can wind your own stator to fita 10 inch diameter brake rotor. I'm sure a lot of different brake rotors have been successfully (or could be successfully) used like this.

 0087adam says:  Aug 18, 2009. 8:25 PM  REPLYIs that a weedeater with a saw blade on it!? (in the background)

 brokengun says:  Aug 19, 2009. 11:29 AM  REPLYYeah basically. It's for clearing woody plants and stuff. We live in the woods.

 0087adam says:  Aug 18, 2009. 8:36 PM  REPLYThat looks really professional...

 0087adam says:  Aug 18, 2009. 8:17 PM  REPLYwould any old brake rotor work for this?

 oddelyodd says:  Jul 10, 2009. 1:37 PM  REPLYgreat project I think it is a good Instructable and if you can send me the schematic and firmware for the controller with the lcd it looks very cool to make forprojects like this one

 brokengun says:  Jul 12, 2009. 6:35 PM  REPLYI didn't end up completing much of the controller at all. Really all I had was a voltage divider circuit to read 0-12 volts and a temperature sensor thatworked on the LCD. I tried to find what little code I did have but I just moved to a new computer and apparently the old stuff is nowhere to be found. If Ido locate it I'll send it though.

I used this LCD: http://moderndevice.com/LCD.shtml I would recommend it. I wouldn't recommend their arduinos.... I bought two and couldn't get eitherof them to work, maybe it's just me.

 oddelyodd says:  Jul 20, 2009. 6:04 PM  REPLYthat's OK but thanks though

 ironforger33 says:  Jul 10, 2009. 4:50 PM  REPLYGreat instructable. Gotta love the name too.

 1234Becka says:  Jun 25, 2009. 1:12 PM  REPLYThanks for the info on your wind turbine and the list of books you got a lot of your info from. On most of the wind turbine "how to" no one gets to the part ofthe type of wires to run from the wind turbine to the batteries. I heard the wires and batteries is what cost the most. How far is your wind turbine from yourhouse, and where are you setting up your batteries? Great job on you project and getting it set up!!

 brokengun says:  Jun 26, 2009. 9:23 PM  REPLYI don't think the wires cost the most but then again I guess that depends on how far you want to run it. I used 3 conductor 6 gauge copper wire, which ispretty expensive stuff... Looking around online it looks like it's in excess of $1 per foot (probably much more for 3 conductor). I lucked out and got minefor free, there were lots of freebies in this project. I also only had to run it down the length of the tower to the box where the battery is. Keep in minethough, that my generator is a 12 volt one and thus requires thicker wires for lower resistance. Most people who would be doing a DIY wind turbine tosupplement their house use a higher voltage which requires thinner wire. This is overall a good idea and I would recommend it as it will definitely saveyou money. Where the money really comes in is the tower, it's hard to get a good, solid tower solution for a good price. A lot of people tend to forget howexpensive it may be.

 whiterabbot says:  Jun 22, 2009. 10:17 AM  REPLYI would like to build a wind turbine on my uncle's property. He has two acres but there are houses close by too. I was wondering if anyone knows if what thestipulations are for putting up a wind turbine?

 brokengun says:  Jun 22, 2009. 11:08 AM  REPLYThey vary depending on your area. I needed to get a building permit and such but it would've made a difference if I was a certain boundary of a city. Iwould suggest calling up your town office and asking what the maximum size tower they allow to be put up. Also remember to get a good clear spot or ahigh tower to get the best wind possible.

http://www.instructables.com/id/7-Foot-Axial-Flux-Wind-Turbine/

 smlkurby says:  Jun 19, 2009. 9:22 AM  REPLYPB Blaster! :) That stuff is amazing!

 brokengun says:  Jun 19, 2009. 10:12 AM  REPLYYou are correct about that.

 rimar2000 says:  Jun 9, 2009. 9:32 AM  REPLYYour design is a good one, it seems. In the 1940's, my father did some similar in the farm, with an old car charger (dinamo), two blades propeller, withoutany calculus, only will and cleverness. The device worked for about 20 years, supplying 12 V DC, I do not know how many watts, but we had all the houselights and radio (with tubes, the transistors didn't exist).

 luvit says:  Jun 11, 2009. 4:36 PM  REPLYi um... i wasn;t born then.

 Rs master says:  Jun 9, 2009. 2:55 PM  REPLYyour only keeping it up for a mounth?

 brokengun says:  Jun 9, 2009. 4:59 PM  REPLYOops, that was old information. I was planning on putting it up at my school. I thought I might have to take it down after a short period of time because itwas on school grounds... etc. Luckily that changed I still should've protected the magnets though. I will update if I am able to do it.

 Rs master says:  Jun 11, 2009. 4:36 PM  REPLYok well it look realy good i dont thin gi have the money for that yet

 coopdaddi says:  Jun 11, 2009. 11:46 AM  REPLYVery well done! I have been doing a lot of research on this exact concept And find your instructions to be very helpful, thank you!

 rockyt says:  Jun 10, 2009. 6:38 AM  REPLYthe pdf seems to be damaged and doens't download.

 brokengun says:  Jun 10, 2009. 7:59 AM  REPLYStrange... it works just fine on my end. Is anyone else having trouble?

 frollard says:  Jun 9, 2009. 3:39 PM  REPLYAbsolutely excellent project! I've wanted to build one for a long long long time. The local rodeo grounds put in what I can only estimate is a 20 foot tall 20 footdiameter 3-winged vawt - estimates are based on the size of the technician they had working on it one day. Ever since seeing one of those on a localbuilding - I want one.