Toying with tensegrity

About half a year of weekly Alexander Technique lessons I doubted a bit about their use. My teacher told me that our body works as a tensegrity system, and I got hooked again. Even more, I decided to get on a teacher training myself - finally I could integrate Buckminster Fuller's ideas actively into what I want to do for a living.

The notion of tensegrity reappeared lately during our anatomy sessions, and I realised that most people seemed to have no idea about tensegrity. I had yet to learn that conceptual knowledge has to be embodied for a full understanding.

I had seen a good instruction for building a tensegrity table, and I wanted to give a shot myself. I decided to start with a proof of concept, using PVC instead of copper, trying to translate the imperial measures into metric, adapting a bit for the conversion.

The first prototype didn't work well, the cord length of the main triangles of the tensules was too long. The second prototype taught me about the importance of prestress for the connecting diagonals, and dampened my hope a bit to soon have a nice self-made coffee table.

So I researched the web a bit to stumble across the building instructions for a tensegrity tower made of wooden dowels and plastic cords, and the next visit in the hardware store was due. I don't consider myself a handy man, but I usually don't shy away from manual tasks. Sawing a dowel, drilling some holes and knotting some strings appeared easy preparations to gain some insights to the dynamics of tensegrity structures.

Working on this model allowed me to work on myself as well - I had no time constraints, no boss, no obligation to finish the project, nothing but my curiosity that motivated me. I felt quite proud after cutting the dowel into twelve pieces of similar lengths (2mm tolerance on 20 cm). surprised about the difficulty finding an easy way to drill the holes and about my patience following the instructions step by step. I prepared everything for four tensuls, again translating from imperial to metric measures and improvising with the chocie of materials.

I didn't find stretchy plastic cord, and used nylon string instead. When I tried to assemble the first tensule, the nylon cords wasn't stretchy enough to put the model together. I realised some frustration about preparing more than 30 pieces of string I couldn't use, but decided to make some bigger loops, this time only enough more one model.

I started off with main triangles, and thought about reusing some of the loops already prepared to see how it works out. The first structure that emerged rigid still looked very crooked, I used different length for the connecting diagonals. But I had entered the third dimension, and now wanted to find out a decent length for this 3d puzzle. I unhooked one diagonal, and due to the tension and flopped over from rigid box shape to a messy bunch of rods and strings. Wow.

I found a good length experimentally and prepared the next set of loops for the remaining tensuls. Fixing the orientation of the rods with rubber strings made the assembly easy and fast, and I had four tensuls ready to be piled on top of each other.

The nylon string didn't stretch easily, and I needed some force to threat the first two tensuls together. Although the lower triangle of the upper tensul hung around without tension, the combined tensuls showed increased rigidity.

Finally, I could tune my first tensegrity tower to balance it out. Stunned by the weird thing I build, I took some photos - unfortunately too blurred to be usable. However, as a picture cannot really capture the surprising qualities of a tensegrity model (unless explicitly designed for artistic purpose), I didn't regret capturing this historic moment for me with a crystal clear digital image. The experience I gained provides me with an embodied memory, and images will accompany the next part of the story.