A HOME-SIZED WATERWHEEL
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The waterwheel is built in the classic "overshot" style (that is, a flume shoots water to the top of the wheel, where the fluid falls into built-in "buckets" ...thus forcing the rig to turn). To get the power providing liquid into "overshot position", Dennis and Robyn ran a pair of 1112 "-inch plastic pipelines 50 feet up the stream. Those conduits capture water at an altitude slightly above the top of the wheel and dump it-at a rate of approximately 45 gallons per minute (the flow, of course, varies with rainfall)-right at the top of the bucketed double disk.
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TAPPING THE CYCLE
The design of the water-pumping system is pretty straightforward. Its most complex element is the wheel itself, and even that has an appealing symmetric simplicity. To construct the rotating unit, Dennis and Robyn first cut two 48"-diameter circles out of 314" marine-grade plywood. They then scribed pencil lines that divided each "pie" into 16 equal segments. Each point at which one of those lines met the perimeter of the circle marked the location of the outside edge of one of the wheel's 16 watercatching scoops. (And a chord drawn between any adjacent pair of these points measures 9-3/8 ".)
Our inventive builders reasoned that the water would exert maximum turning force on the wheel if every bucket held its contents as long as possible. The dividing boards, therefore, needed to be laid out so that they angled steeply up toward the flume's spillway. (That way, an individual container would rotate more than one-third of a revolution before its lower side became horizontal and dumped out its contents.)
To set the desired slope for each bucket, Dennis and Robyn placed a framing square so that one side of the tool lay on one of the 16 radial lines, while its other side intersected the outer tip of the secondradial line back on the wheel. The board was placed along the line that was thus formed, to connect the two radii (see "Wheel Layout" diagram). Each 1 X 6 section thereby formed a 90° angle with a radial line at its inner end, and worked out to be 19-112" long. In addition, since every board overlapped a neighboring plank, it served as both the front side of one bucket and the back piece of the next!
After all the boards had been laid in place and checked for alignment, the two men glued, nailed, and painted the assembly. In addition, Dennis and Robyn added a drain hole-between the buckets and the wheel's centerpoint—to release any water that just might manage to sneak through to the interior of the spinner.
