Motorized Fan

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Playing around with the large and small K'nex gears, we built up a sturdy gearbox that used two pairs of blue and red gears to twice raise the rotational speed of a hand crank. Since the K'nex blue gear has 14 teeth and the red gear 34, each such pair of gears increases the rate of rotation by a factor of about 2.4. For two pairs of gears, the increase is nearly 6X. Additional increases are theoretically possible by adding more gear pairs, but the torque required to get the whole gearbox moving increases dramatically. Starting out as a hand-cranked model, the K'nex Motor Pack (shown) was later used in the fan to provide a blur of motion for four fan blades. These blades are a colorful variation on old-fashioned windmill vanes, and are constructed from yellow rods and orange connectors. Another feature of the K'nex fan is the orientation of the dark-grey axle spacers in a spiral pattern, which produces an interesting visual effect when the axle is in motion.