Today I am going to show you how to build a functioning wind turbine. For our second year project we were given the task of producing a wind turbine that could power a small motor. Whichever team produced the most power would win the competition and prize.
You need: MDF board
Assortment of gear sizes
Step 1: Support Disks.
Here we are going to make the two disks that the turbine blades fit on.
First of all, mark a centre point on your MDF board. Use a compass to draw a circle with a radius of 160mm. Using a band saw, cut the circle out and use a sander to smooth the edges. Trace around the circle and use it to produce another disk of the same size.
Find the centre point of these circles and use it to draw a 5 pointed star on each one. These lines will be used to align the turbine blades further on in the project. Halfway down each line, mark a point and then measure a point 5mm to the right of the line and mark a cross. This is Glue or pin a square onto the centre of each disk to add support to where the axle will be sitting. Finally drill a 9mm hole through both parts.
At the end of this step you should have 2x MDF circles split into 5 segments.
Step 2: Turbine Stand.
In this step we are going to make 2 triangles to be used as stands.
Using whats left of your MDF board, draw a right angled triangle big enough so that when your turbine is assembled, there is enough clearance for the turbine to spin. Use this to draw another triangle of the same size. Cut both triangles out with the bandsaw. To make your turbine more aesthetically pleasing, use the sander to curve one corner of the triangle into a circle. Drill a hole big enough for your support bracket through the curved corner.
Step 3: Turbine Blades.
To make the turbine blades you first have to mark or score a line down both sides of the thickest dowel. Now, mark a line down the long side of each plastic rectangle (80mmX320mm) 5mm from the edge. Along this line mark crosses at 30mm intervals. (This is so that the pins that you place down both sides of the dowel don't match up). Now, using a vice or glue, align the line on the plastic sheet and the line on the dowel. Hammer pins through the plastic into the dowel securing the two together. The easiest way to do this is to put the first and last pin in so you can align the plastic and the dowel easier.
Attach another plastic rectangle down the other side to form a triangle and glue the 2 plastic edges together using dichloromethane . Repeat this for the other 5 pieces of thick dowel.
Step 4: Axle.
Take your 12mm diameter aluminium shaft and cut it to a length of 410mm. Next use a lathe to mill each end to form the step down to 9mm on each side, 30mm long on one side and 10mm long on the other. Drill a 4.1mm hole in the 30mm long end.
If you have a press available use it to press-fit a 4mm diameter 30mm long steel rod 15mm deep into the drilled hole on the aluminium.
Step 5: Gearing.
We originally planned on using a standard gear pack (that you can buy at any DIY store) but when testing, we discovered that the maximum ratio we could produce using these gears did not give us the power we were hoping to achieve.
To solve this problem we designed a gear on illustrator that would work with the rest of the pack we were using but would give us a bigger ratio. We laser cut this part from 5mm thick acrylic plastic. The standard gears are in red and our laser cut gear is in white. After getting the white gear laser cut we drilled a hole through it and glued one of the small gears in from the standard pack so we would have a method of fastening it to the axle.
Attach the smaller gear to the motor.
Step 6: Support Bracket.
We designed this part to fit into the turbine stands, this would support the bearing and ultimately the axle. This part was lathed by our workshop technician. Once created, slide these into the turbine stands at the rounded ends. Push your bearings into place.
If you don't have access to a metal lathe, you can just drill partly through your turbine stand and then glue them into place.
Step 7: Assembly.
1. Supporting one of your turbine blades in a vice, align your support disk and hammer a pin halfway into the thickest, dowel (make sure the 'tip' of the triangle points towards the centre of the circle). At this point you should have all 5 blades attached to the support disk. At this point you can slide your smaller diameter dowel pieces into the gap between the 2 plastic sheets on each blade and nail it to the point you made earlier on your 5 pointed star. Do this to all the blades. Once all your dowel has been attached, slide your axle into the hole you've drilled though the support disk. Once done, slide the second support disk down the axle, align everything and nail the second support disk into place. This part is fairly difficult so it helps to have a vice or someone to hold it steady.
2. You should now have an almost 'bird-cage' like contraption, with all the blades pointing inwards. Slide the turbine with axle into the support brackets on the turbine stand.
3. Make a base out of a solid piece of MDF. Nail your two turbine stands to this base making sure they are very secure (this part is important because the turbine can generate enough lift at full speed to lift the front up slightly).
4. At this point you should have your actual turbine assembled and connected to your base.
5. Attach the biggest gear to the protruding piece of axle and use grub screws to secure it in place.
Step 8: Finishing Touches.
As finishing touches,
1. UPOL the dowel and plastic where they join like in the picture. Let this dry and when it has, put masking tape over it.
2. Put masking tape along the edges where the plastic meets.
3. Drill a hole through the stand big enough to house the motor. Make sure this is secure.
4. Align the small gear on the motor with the big gear on the axle.