Monday, 1 July 2013


The triangle seems most obviously the most stable configuration, and it can be found in a lot of my tensegrity structures. Three trajectories building the eight intersections of a cube would be one example, which transform into eight triangular opening of an octahedron. Two triangles that add up to four triangles in three dimensions of the tetrahedron would be another.

While showing my tensegrity structures in the street I skipped the 30-strut structures for pragmatic reasons. I carry about 13 items around - 3 six strut icosahedra in different sizes, 2 octahedra, 2 tetrahedra, 2 cubes, 2 joined tetrahedra, 2 pentagonal prisms that build some donation vessel.

While it's easy enough to perceive the octahedron as a kind of spherical object, it's much less obvious than a 30 strut icosahedron, or the 24 strut vector equilibrium, or it's dual, the rhombic dodecahedron. Just to keep me busy, I started building the latter two while I'm sitting around, and discovered some interesting quality.

Vector equilibrium

Instead of building strut by strut, the VE and its dual invite themselves to be composed of triangular modules. Actually, the same applies to the cube and octahedron.
Rhombic dodecahedron

The triangular module used to build the above model connects the struts in the middle of the attached string, which works easy enough to build the VE and the dodecahedron. The dodecahedron balances quite easily on its 'square' corners, the VE on its 'rhombic' corners.

Usually, the triangles are rather located on a one third/two third ratio, at least when I aimed for maximum symmetry. While the half configuration works quite satisfying for the larger structures, building cube and octahedron from the same 3-strut modules produces rather skewed results.

Skewed octahedron
The four 'modular' triangles are larger than those that emanate by connection, and instead of having square corners, they are rather rhombic. The same applies to the cube - four intersections have the size of the original modules, the other four end up much smaller.

Skewed cube

The reduced symmetry in the skewed versions still has lots of aesthetic appeal, and invites itself to be build in multicolour. I appreciate more and more the opportunity to experiment with different ratios of tendon lengths that elastic string allows for.