Introduction: Small Wind Turbine Blade (6 Foot Dia.)
This Instructable will give you a step by step process on how to carve a real wind turbine blade out of wood (not those fake ones from a 4" PVC pipe, but they are cool too.). This was designed by me, a real Aerospace Engineer, using real airfoils, and optimized for a small wind turbine at lower starting wind speeds.
I promise you it is easier then you think. I will even provide you with a pdf drawing that you can print out, and use as a template. So I want everyone to start making wind turbine blades. Well, what are you waiting for, GO!
If you are interested in how to design your own go here:
By the way, after you make these you need to make a hub, but that is easy too. And make or buy a motor, but you can get them cheap on Ebay. Just type in PMG (Permanent Magnet Generator). They are nice because they do not require a gear box because they operate at relatively low RPM (500 RPM for this blade).
Step 1: Printing the Airfoil Templates (on Paper)
Okay, step one, lets make some blade templates. I will make this easy for you. All you have to do, is download the PDF here:
I Also attached it to this step.
This drawing is 1:1. Yes, 1:1. Which means, all you have to do is print it out, probably in sections if you don't have a plotter. Which most people don't. But you can easily select different regions of the drawing to print, and then print them. Be sure you don't have any scaling on, as this will change the size of the print out to fit the paper, you don't want to change the size.
As you can see from the drawing below that each section corresponds with a given station along the blade. When you start carving it is critical that you mark the blade sections and their corresponding station (ie. A-A, B-B, C-C etc) So when you start carving you know which section goes to which station
Step 2: Making Airfoil Templates
Once you have your sections printed out, from the previous step. All you have to do is glue them to something hard, like: Cardboard, thin aluminum, construction paper, plastic sheets, Mylar, wood, Balsa, something that will hold its shape, but you can easily cut with scissors, tin snips, band saw, jig saw, scroll saw.
Once you glue each template section to the material of choice, just cut out the section. You can see below what each section will look like. Don't forget to mark each section with the correct letter.
I had a friend with a water jet cutter, so I cheated, and had him cut them from 1/16" Aluminum. But you really could use anything that will hold its shape.
Step 3: Gluing the Wood
To me, this is the least fun part. You have to make your wind turbine blade of something. I found that soft pine, found at home depot is fine and very easy to carve. And you can harden it later. You can also use hard woods, like maple, oak, etc, but good luck carving it.
I have provided a very simple drawing with dimensions, showing the easiest way to glue up few 3/4" boards so that carving goes very quick. Less material to start, means less material to remove.
Download drawing here or below:
When you get all the wood ready to glue, prepare your clamps, and use regular wood glue. I use Tightbond brand glue, which is also available at home depot.
Apply glue to both sides of each board, and get your clamps ready. Once all the board are together, clamp that sucker down. I mean hard! You cannot have any gaps, gaps will ruin everything. So make sure to have lots of clamps or very heavy weights. Do not leave any air gaps.
Step 4: Band Saw Blade Planform
I take the print out of plan-form (top view) of the blade, and tape it onto my glued-up boards. The mark out the blade plan-form (top looking down onto the blade). Then use a band saw or jigsaw to cut out the plan form. Below is an image of the blade after the plan-form is cut out. you can see it lays on top of the drawing, and matches its edges. You can also see that each section can now be marked (ie. A-A, B-B, C-C, etc.) Be sure to mark them good, as this will be used to carve the blade.
If you have a regular printer, you can print out sections and tape them together. It's not that hard. I promise.
Step 5: Marking the Leading and Trailing Edge
Basically , all I do is place my template at each section, which I marked from the previous step, all around the blade. I align each template on the front side (leading) edge and mark the airfoil shape as it would touch that blade station. See below, C is marked at C, and D is marked at D. Where the most forward edge touches the line is the leading edge. I do this for every section along the blade. I then draw a line from peak to peak. This line is the leading edge line. And will guide you where NOT to cut. I repeat this is the line in which you do NOT want to remove material. You want to remove material above and below it, but that line is suppose to be the most forward part of the blade, and will never be cut. Make sense? I hope so, or your in trouble. I repeat this with the back edge (trailing edge).
FYI, leading and trailing edge is an Aerodynamics term, which as you may have guessed, is how the airfoil 'sees' the air. Leading edge being the first part of the airfoil or wing to feel the air, and the trailing edge is the last. See being a nerd is cool.
Step 6: Hogging Out the Wood
If you have gotten this far, the most fun part starts now.
You will use a planer, draw knife, or spoke shave to remove a bulk of the material. This tools are eaisly found in most wood shops, and can be purchased at home depot for cheap.
You can see I just remove the material up to the leading and trailing edge lines, I never remove material on the leading or trailing edge. If you are getting nervous, just place the template at the correct station and see if it fits. You prolly have a lot to go. But I do it anyway.
Step 7: Using the Templates to Get the Airfoil Shape
If you used pine, this should go quick, as every time you draw with your knife the material just melts off. As you start getting close to the final shape, start laying your templates at each station, and marking the 'high spots'. Usually with a pencil. And use a spoke shave to bring in the high spots. See below as we lay template E-E onto its corresponding location, you can see high spots. Then we remove them with the spoke shave in the next image. Finally, sand the blade, and it will look great!
Step 8: Harden and Paint
Since Pine is a soft wood, it is susceptible to being nicked. I suggest you apply a few coats of wood hardener.
Its cheap, and will make your wind turbine blade more durable.
Then paint it. Don't get the cheap spray paint, it will take you 3 coats for it to even look good. Just pay the 6 bucks and get good stuff.
Step 9: More Blades
So now, you can do it 2 more times to make a total of 3 blades, or you can duplicate it:
Video of Propeller Duplicator in Action!
Step 10: The Hub
I have a hub already designed for this blade, it is quite simple you only need two pieces of wood or metal. You can print out the 1:1 drawing, and band saw out the shape from wood, or use a mill to cut out of aluminum.
The drawing is linked below and attached:
Ignore the crazy blade grips, they are not needed for this design, only the front and back plates, marked FWD HUB MOUNT, and AFT HUB MOUNT. Again, this is a 1:1 drawing.
Step 11: Motor and Assembly
I am not going to leave you in the cold without a motor. Here is my recommended motor, which I designed this blade for. It is a great motor, and reasonably priced.
This is by far the best motor around.
Have fun. You can use other motors too, or make your own, you crazy nut!
Step 12: Download the 3D Model at GrabCad
I have uploaded the 3D model of the wind turbine you can build at: