Tuesday, June 11, 2013

Starting a korgome icosahedron

The finished side of an icosahedron woven in sheet metal using the corrugated kagome (korgome) technique.

These aluminum weavers were cut on a paper trimmer from 10"-wide flashing that is about 0.2 mm thick.

The width of the strips is 1.21".

The weaving units are 8 squares in length. I tried for 1.25" spacing between perpendicular folds—the measured value is 1.23-1.28". I tried to make the diagonal folds at 45 degrees.

In the icosahedron, the little pentagonal engagement windows end up measuring about 0.12" from base to peak.

In flat korgome the nominal value for the dihedral angle in the valleys is 70.5 degrees. I found that in making such a strongly curved, points-out surface, it helps to open the valleys somewhat before starting the weaving.

The same korgome icosahedron, here viewed to the inside. From this side the cube corner pyramids act like retroreflectors. 

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