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side view of garden-stake-and-nylon-twine tensegrity bean teepee on grass

On June 23, 1999, I first assembled the tensegrity bean teepee. I also put together a press release for it. After several years out in the garden, the ends of the base struts rotted and it fell over and I never did grow any beans on it. My solution for this problem was to saw off the ends of the bottom struts and recompute the structure with the new lengths for the base struts and connecting tendons. The other tendons I constrained to maintain their previous lengths though their relative member forces did change somewhat which means technically I should have retied them to get everything exact. The changes were very minor though and nylon twine is pretty forgiving so I didn't bother retying tendons which were already in place. Avoiding that retying was the main reason I recomputed the structure in the first place. I think it actually looks better with its new base. These changes were implemented on September 17, 2003, too late for beans where I live unfortunately.

Here is a close up of the base of the structure:

base detail of garden-stake-and-nylon-twine tensegrity bean teepee on grass

I really do plan to grow beans on it eventually. This time when I put it in the garden, I put old plant containers from the nursery under the base struts. I hope this will retard the rotting. This arrangement can be seen in the first photo of the Seven-fold Equi-tendoned Prism. I don't think I can make the base-strut-shortening trick work a second time. The original struts are one-inch-square (2.54 cm) 44-inch-long (112 cm) hardwood garden stakes. The shortened struts are 38 inches (97 cm) long.

After keeping it in the garden for a couple months, no beans had sprouted (it was a cool spring and a shady garden), so I took it and nailed it to the top of a half whisky barrel I use for container gardening on my sunnier porch. The shorter base legs I think made this easier than it would have been otherwise since they had a small angle relative to level ground, and there are no rot problems since it doesn't contact the dirt. The picture below shows it on August 10, 2004, with a crop of string beans. There are some tomatoes growing inside which are not very visible.

bean teepee with beans


Four-fold Reduced-Symmetry Prism Index Seven-fold Equi-tendoned Prism