“In the 6 years since I developed the first forge blower,” writes Primitive Technology‘s John Plant, “I had made very few improvements to its design. So I decided to do some research and development to see if I could improve it’s efficiency.”
In this wordless episode from the Far North Queensland-based engineering YouTube channel, Plant molds a new clay casing and tuyere, as well as three new wind-generating fans, impellers made from cane and folded leaf blades. He continues:
“From my research, increasing the number of fan blades from 4 to 8 yielded an increase of 19% volume of airflow. So I set about building a better fan.”
“Instead of splitting the rotor and inserting blades made of bark into it, I made spokes from split cane to hold the blades leaving the rotor intact. This increased the longevity of the rotor, as well as the spokes being heavier, contributing more momentum, assisting the impeller in winding back in the other direction after each rotation. Instead of bark being used to for the blades, simple (and easier to find) folded leaves formed the blades. These, being flexible, are less likely to break against the walls of the housing as stiff bark does. Finally, a lid was added to the housing to make maintenance easier.”
“The new blower works better than the old one with more airflow occurring. I experimented with different numbers of blades on the impeller (4,6 and 8). The more blades used, the slower the impeller can be spun to produce the same airflow. This makes it easier to operate as the users arms don’t have to move as quickly, making it more ergonomic. This conservation of effort will be important in iron smelting later.”
Watch more Primitive Technology on TKSST, including:
• Making a Forge Blower
• Simplified blower and furnace experiments
• Creating wood ash cement from scratch, an experiment
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