Market preparations

Egg of Columbus

I got lazy since the last market, although I could replenish my stock of smaller sculptures after 5 pieces changed hands. I build two more 6-strut icosas, and have plenty of 12-strut octas in various sizes left. The new show piece is a slightly skewed 30-strut icosa, using two strut length and two colours, the Egg of Columbus.

Unfortunately, I can't get Triple Y in my old Volvo, and the larger structures don't like transport too much. The weather permits the use of more colour as well, so most preparations considered producing certificates, preselecting models for tomorrow and printing more business cards.

I'm overwhelmed by the space-filling character of these structures. My lounge room became an ecosystem of many variations of tensegrities. The heater ventilates hot air into the air, which moves Windspiel around, without ringing the chimes. At the basis of Windspiel, a pack of similar sized left-over experiments from the toolkit development lingers around. A short tetrahelix invaded a corner of Triple-Y, which itself seems to duck away from a large Class-2 tensegrity tetrahedron, which hooked itself into a band of x-modules. The modules connect like a vine the space between the lamp and the window, growing towards the artificial light.

The lamp also holds a cuboctahedron up, with a 6-strut suspended in its center. Windspiel repeats the theme, a small tensegrity suspended in a sphere. Out of seven basic geometric shapes an evolution of sculptures emerged, a constant recombination of materials and methods in different scales. Parts of this zoo will have the opportunity to find a new home, ending up in curious hands.

As I still have no idea which models to take, I simply will sleep the decision over.

Frog in the well

Frog in the well

I went to the local hardware store to find a small table saw. It could make preparing wooden struts much faster and even more precise than the Dremel, but I'll have to wait to find out. Instead, I brought a 3m aluminium tube home and got busy.

The first hole I drilled was too wide to hold a knotted nylon string, yet I decided to worry about this fact later and prepared three alu struts for a prism, each with three equidistant holes about 2cm from the end. Doubling the tendon should provide additional strength, and a knot of two strings of nylon held safely in the hole.

I used the measures taking from a bamboo strut structure with nearly 1m struts. I adjusted the final tension by pulling the vertical tendons overly tight, and then knotting off between 2 and 5 cm of it. I ended up with the box shape I wanted, with decent tautness. I did a stress test by putting a zabuton on top, and it took the load nicely.

I pushed the end of the strings back, and riveted the end of the tubes. The construction details hidden, not perfectly but nicely balanced, evenly spaced holes made it a satisfying piece by itself. Yet it invited me to do more, to use it as base for a more complex tensegrity.

After installing two bamboo tensuls into the top triangle, and playing around with spheres on top of them, I build a 30-strut icosahedron with nylon strings. I chose a strut length I didn't use before, and estimated the string length required, with nasty consequences. The overall tension split one after another strut, as could drops from just one meter height.

The drop resistance might not have improved, yet in its current installation the structure is unlikely to be exposed to excess stresses. The sphere now rests on a single smaller tensul, with a 3:1 ratio of strut length from basis to middle part, and a 3:1 ratio of strut length and upper triangle of the support for the sphere.

Instead of a tension triangle, the base of the support prism get its tension from three connected nylon string loops, connected to the lower end of the struts. A small Chinese bell with a frog sitting on it is suspended from the center.

Now all I need are three columns to elevate the model some more. The aluminium struts were easier to work with than I thought, and invite bigger structures.

Windspiel

Tensul tower with wind chime and dodecahedron

While I seem far away to build a sculpture with musically tuned tendons, I simply used an older idea move to transform little movement into sound: a wind chime. I suspended one of those from the top corners of a two-stage tensul tower, so that it has room to swing around. Just for show, I connect a large dodecahedron into the top triangle. Impulses travel now very unpredictable through the structure. It still needs anchoring for outdoor use, as you see in the video.



The dodecahedron came lose after the sculpture toppled the first time, I used it as reference for the wind speed. Shortly I kicked it back to rest next to the tower, a gust came. It looks like the weight of the wind chime pulled the structure over. I'm still surprised how easy the wind blows over tensegrity towers, as they offer only little surface area. If only I had some outdoor space for longer lasting experiments with stability in wind and weather....