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“Edge” tension lines define the edges and the sides of each module. The three-way column has three edge lines for each module. In most cases, edges carry less tension than draw or sling lines. |
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“Draw” tension lines pull the modules toward one another. In the three-way column, each module is connected to each neighbor by three ascending draws and three descending draw lines. |
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“Sling” tension lines suspend the modules, performing like the slings used in rigging work. They connect one module to the next and are generally in opposition to the draw lines. In a three-way column six slings are required in order to link two modules. |
Above is a three-way module. In this simple figure all tension lines can be called edges: six end-edges and three side-edges. They define, roughly, a triangular prism. When viewed through the vertical axis the module has a left-rotation helix. The opposite is true when viewed from the side: the struts relate to one another in a clockwise or right-rotation helix. |
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helix
Left
helix
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Three module, three-way column
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