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“One form of intermediate technology employed in my shop, the human-powered machine, provides an alternative to both the hand tool and the power tool. At this time, my tools in this category include a treadle-powered band saw, a hand-cranked drill press, a pedal bench grinder, and treadle metal lathe. The lathe and drill press are more than 100 years old and were manufactured to be human-powered. The 12" band saw is of more recent manufacture and came to me with a 1/4-horsepower electric motor. I use all of these tools regularly. However, I will describe the band saw in some detail as it is by far the most used. The saw is mounted on a purpose-built stand equipped with wheels. Without an electric cord, it can be easily moved around the shop or into an adjoining room. In place of the V-belt pulley driving the lower wheel is a cluster gear/freewheel mechanism from a 10-speed bicycle. A bike chain connects the freewheel sprocket to the treadle in such a way that for every 1" of treadle movement there are 2" of chain movement at the sprocket. This gives a higher speed to the saw and a better balance of power available. As the treadle is depressed, it spins a spool, winding up a cord which flexes a spring. The energy stored in the spring returns the treadle to its starting position. Four small lead weights are screwed to the perimeter of the band saw’s lower wheel, giving mass to the aluminum wheel and helping to smooth out the discontinuous application of power.” – Harry Bryan, excerpt from “Intermediate Technology in the Shop: Inspiration from E.F. Schumacher’s Small Is Beautiful” in Issue Eight Link to subscribe in our profile. #mtmagissueeight #harrybryan #humanpoweredtools #bandsaw #efschumacher

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WOW!!!

Tenone e mortasa

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Tenone e mortasa

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