Hugh Piggott’s A Wind Turbine Recipe Book gives a step by step guide for manufacturing a range of SWTs from 1.2-4.2m rotor diameter using only basic tools, techniques and materials. Figure 2‑5 shows the carving of blades from planks of wood and the grinding and welding of a tail and mounting frame from standard lengths of steel using Piggott’s open source design in a basic workshop in Mozambique.
Manufacture of a SWT using simple tools and techniques in Mozambique. Photo courtesy of The Clean Energy Initiative.
The main bearing is from the wheel of a scrap car and much of the steelwork can be made using reclaimed pieces of metal. A specially designed Axial Flux Permanent Magnet (AFPM) generator is built to match the blades by casting powerful neodymium (NdFeB) magnets onto steel rotor discs using resin, which is also used to set specially wound copper coils into a stator. The AFPM generator topology is particularly simple to manufacture due to the fact that it uses only planar components and is ideal for wind power as it can be specifically designed for low speed operation. Piggott designed the machines to provide power for his home community of Scoraig in Scotland and over the last 30 years, he has continually refined the design to improve reliability, lower costs and create a machine that is well respected across the globe for its durability, simplicity & adaptability (Leary et al., 2012). The diagram below describes each of the key components in a Piggott turbine and shows how they fit together.