A brief post about the importance of prepping and prototyping for a build, and a couple of things that came up in the prep for the Golden Gate STEM Fair event. First, there’s just the sheer volume of supplies for such an event. Here are lots of beads getting outfitted with twist ties, for example. Also, to make the sculpture look more attractive, the boxes needed to be painted, 300 each of three colors.
More importantly, you get a feel for the structural characteristics of your medium. Experience (and physics) show that some sagging of horizontal members in a structure like this is inevitable, but full-scale stress tests like this one revealed that the stiffness of the struts varied greatly depending on their orientation. With the top row of boxes vertical as shown, the sag was acceptable, but rotated 90° (about the long axis), the struts were far less rigid, with all of the edge-to-edge joints acting like hinges.
As a result, additional methods of attaching boxes edge to edge needed to be developed. First, the boxes could be assembled with two flaps still sticking out, like so:. That way the flaps could be taped to the adjacent boxes in the structure. The cubes are still positioned edge-to-edge, just linked more securely. And second, for making the double diagonal row of boxes along the middle of each truss, we could just slide the flaps from adjacent boxes into each other, like this:
These changes produced very rigid struts, as you can see in the picture below, leading to high confidence going into the Golden Gate STEM Fair build.