After some thought, I realized it isn't necessary that the outer girdle of the Concentric Five-fold Prisms be arranged so a sequence of three connected side tendons connect adjacent struts to one another as in most non-girdled prisms. Here the girdle is connected to the inner prism so that a sequence of three connected side tendons goes from one end to the other end of the same strut of the inner prism. For now I think I'll leave this structure completely conceptual, but if you're interested in building it, the data is below. If you do build it, send me a photo and I'll put it here. This design was completed March 2, 2004.
|Average tendon force = 1.82257|
This tensegrity reminds me of nothing so much as the witchs' cauldron in William Shakespeare's Macbeth:
1. Witch. Thrice the brinded cat hath mew'd.|
2. Witch. Thrice, and once the hedge-pig whin'd.
3. Witch. Harpier cries, "'Tis time, 'tis time."
1. Witch. Round about the cauldron go;
In the poison'd entrails throw;
Toad, that under cold stone
Days and nights has thirty-one
Swelt'red venom sleeping got,
Boil thou first i' th' charmed pot.
All. Double, double, toil and trouble;
Fire burn, and cauldron bubble.
from Macbeth, Act IV Scene I
I received the first rendition from the audience from Eric Phillips, an
undergraduate at the School of the Art Institute of Chicago,
on March 22, 2004:|
I imagine it could use more tension. I usually decrease all the tendon lengths 2% relative to what they will be when they are prestressed. The tighter tendons I decrease more and the looser tendons less, but I make sure it averages out to 2% and I do all right, with fishing line anyway. I never have things lean like that. But wow, I never expected to get anything so quickly!