This is a step by step description to building a small wind turbine capable of generating electricity and tested in a wind tunnel.
Step 1: Materials
The following materials are required to build the wind turbine:
500mm x 500mm x 10mm MDF board
1.5m of 3mm diameter wooden rod
1000mm x 1000mm x 3mm wooden sheet
50mm x 50mm x 150mm wooden block
230mm length of metal rod diameter 10mm
6 threaded metal rods length 430mm
32 metal nuts (fitted to threaded rods)
Plastic gear pair (optimum ratio)
Perspex block 25mm depth
Step 2: Assembling Hub for Wings
The wooden block was shaped to rounded cone on a wooden lathe machine. Six 10mm holes were then drilled into the hub spaced 60 degrees apart in order to fit the blades. The back of the hub was then drilled by a 10mm diameter drill bit to a 15mm depth in order to fit the rotating metal shaft.
Step 3: Blades
A leaf template was used to cut six identical leaf shapes from the thin wooden sheet.
Leaf dimensions : height 178mm, width (max) 40mm.
The wooden rod was cut to 200mm length and glued onto the back of leaf as shown.
The six blades were then glued into the wooden hub using PVA at an angle of 35 degrees.
Step 4: Perspex Hexagons
Using a CNC milling machine, 3 hexagons were cut from the perspex block, six cut through holes were included in the hexagons in order to fit the threaded rods. In one hexagon appropriate holes were also milled for the shaft and bearings to run through the horizontal axes and in another holes for encasing the motor were also created.
Step 5: Preparing Board and Rods
Using the vertical holes in the hexagon as guides, six holes were drilled through the MDF board and the threaded rods were attached in place by nuts countersunk on the underside with nylon nuts.
Step 6: Assembly and Gearing
The hexagonal components were attached to the metal rods secured by nuts. The blades connected to the hub and metal shaft were placed through the corresponding holes in the blocks as was the motor in the hexagon below. Similar to the picture, the gears were attached to the metal shaft and motor, height adjustments are easily by rotating the nuts. To prevent the gears from slipping, nylon nuts were used for holding the larger in place.