Construction Updates 3
From Batcountry
See Construction Updates Part 1, Part 2, Part 3, Part 4, Part 5
Here we show Part 3 of our construction process for Bat Country: Generation 2
Click on photos to enlarge.
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[edit] Layer 3: Building a Gen 2 Sierpinski Tetrahedron
The top of Layer 3 is 9 horizontal bats, and we assmbled them even easier than we expected. To make room for the 2-bat couplings, we needed to use our jack to lift the base edges of the tetrahedron, one at a time. This effectively pushes the 3 tops apart to make room for the new bats. As is visible in the center photo, the two bat addition is enough to make the base edge of the sculpture rigid. Paul is standing on the base edge, yet it hovers a couple inches above the brick that had been holding it up before. Yeah! This layer of 9 horizontal bats is a bit springy, but the 3 large tetrahedrons below are now totally solid.
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[edit] Layer 4: Building a Gen 2 Sierpinski Tetrahedron
Layer 4 went up in a snap! Can you see how happy Paul is?
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[edit] Gen 2 Sierpinski Tetrahedron
The Generation 2 Siepinski tetrahedron is now complete! It appears to be quite solid.
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[edit] Checking for Deformation
The Gen 2 sculpture weighs about 800 or 900 lbs and stands over 10 feet high. So, before Gwen was willing to climb to the top, we needed to verify that it is as solid as it appears. We measured the normal gap between the two facing plates of the joints unloaded. Then we measured the gap on the fully laden joints. Comparing this measurement to several other joints, we found any deformation is totally negligible. The force does not deform the joints more than the typical variability across uncompressed joints. The right photo shows how very straight the bottom edge of 4 bats is. There is no visible sagging! When we stand on it, we can barely feel it move.
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Here's Gwen on the complete Generation 2 Sierpinski tetrahedron.
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[edit] Additional Views
The complete Generation 2 Sierpinski tetrahedron.
We shot the next two photos lying on the ground. The top quadrant forms a diamond from three differnt points on the ground, outside the base. The zenith view is visible from the inside, at the very center.
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From some points infinitely far away, the bats align to form a Gen 2 Sierpinski trangle. The alignment of the bats is distorted by foreshortening. I think we should plant a pot of jasmine vines at each base corner and watch the tendrils grow up the sculpture.
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[edit] Machine Man Dan
This is Dan. His machines made the joints for us. We gave Dan a digital file of the joint design (Solidworks), and Dan used his machines to laser cut the joints and their holes from steel sheet, and then another machine (a press brake) folds each crease.
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This completes Part 3 of Construction Updates.
Go on to Construction Updates 4.
All images, designs, and text on this site © 2005-2008 Gwen Fisher and/or Paul Brown. Permission required for any capture or reuse.
