Best thing ever

Using phone and computer to document my latest piece has been frustrating, to say the least. Working on 'Diamond DNA' got me exhilarated, and the results exceeded my expectations after the idea came to me.

Base joined tetrahedral tensigrity

The diamond structure, two tetrehedra joined at the base, shows an interesting balance along its central edges. I presented the smaller versions upright, along the axis of compressability, suspending two thirds of the material with only three points of contact to the ground.

It's the Illuminati tensegrity - 2 triangular and 3 square corners, the geometry strengthening diamond. Build properly, it will balance on the square corners around its girth, albeit very delicately. Suspended, it should show horizontal stability between the triangular corners.

I experimented with connecting the former corners (crossings) centrally instead of outlining triangle, squares and pentagons. I'm not too sure about the classification of tendons connecting in a hub without compression elements, but it adds functional and aesthetic qualities.

The central junction of three corner tendons can act as a mount point for anything suspended in the centre. I had a spiral made of six shorter sticks which needs a pull from either ends to maintain a 3d shape. I looped string around the centre of the outer sticks and attached the elastic string to the junction of the two triangular corners in the structure.

I did my best with a random spray job for the outer struts, balanced on one triangular corner it measures more than 2 metres. I have no idea about its durability - it uses elastic strings around its girth (which I might replace), and elastic to suspend the central spiral.

While I liked to call my sculptures 'kinetic', this one fits the description. The slightest amount of wind gets movement into it, either by rotating the centre or the entire structure. It's like a mothership of randomness, another turn will happen, unpredictably. Different perspectives provide different colour aspects, just like the rotation. Any capture seems unique, like an elephant felt up by the blind.

So I indulged in making a clip, which is still rendering in the background while I type. No idea whether I'll get in copyright trouble when uploading it, I haven't even bothered watching the final result besides bits of preview. If you're in a hurry, don't bother watching. It'll be about 15 minutes without anything spectacular happening,

The raw footage still captured lots of detail I was interested in than the GoPro footage I took before. I love the balance the single point of suspension provides, as well as the independent movement of the spiral in the centre, even though the twist pulls the entire structure together.



PS: This piece brought me most excitements from any of my creations. I had some pieces hanging, and enjoyed the movement. Many delicately balanced pieces were blown over, exploring the rotary power will bring another dimension into my work.

Class 2 tetrahedron

Tensegrity structures still wait for more popularity. While my fellow market traders got used to them, and spend some time playing with them, it's still rather one in hundred passers-by that identifies my work as tensegrity.

I shied away from investigating tensegrity theory since I started building sculptures, but I renewed my research lately with some surprising findings. I realised that I reinvented the wheel - the Unholy Grail uses the structure of Bob Burkhard's Wheel 2. When I browsed Bob's great site again I stumbled upon a Class 2 tensegrity tetrahedron.

I still have some models using eyebolts available for recycling, so I considered rebuilding a tensegrity structure with joints. I threaded the eyebolts of two struts together, which creates a multi-directional joint. A class 1 tetrahedral tensegrity needs 6 struts, and a bit of imagination to detect the tetrahedral shape. The hinged class 2 tetrahedron only requires 4 struts, and seven tendons.

I had no idea about the precise tendon length, nor how the joints would affect the build process. I started with elastic tendons for the edges, and a fixed tendon between the joints. The nightmare began. I hoped that the elastic cord would allow me to 'stretch' the model into a stable position, but the jointed struts kept turning and unhinging some outer tendons. The mobility of my improvised joints backfired, and after some variations of central tendon length, outer tendon length and order of attaching outer tendons I gave up.

Unlike many nicely rendered tensegrity structures one can find on the web, Bob Burkhard showed two photos of actual models showing this class 2 tensegrity. Knowing for sure that this idea can be build, using quite familiar connection types, I reflected on my difficulties during the failed attempts and devised a new strategy.

I used nylon cords with little bowline knots at either end - this should limit slippage of the outer tendons, and give equal length. Even with fewer components than most class 1 models, this build remained challenging. At first, I used a metal hook as connection between joints, with little luck. Then I limited the mobility of the joints by tying elastic cord around it several times, replacing the hook as central tendon.

After several attempts all outer tendons got connected, and shaped a tetrahedron. I didn't let go of the struts, the model didn't feel self-sustaining yet. The elastic cord made it easy to shorten the central tendon, and gave the model stability. It still collapsed, and sometimes outer tendons became loose when I played with it. It still takes me patience to pop it back into a stable 3d state after a collapse. I closed the eyebolts, so that the tendons stay in place.

The final result stunned me. The outer tendons clearly delineate a tetrahedron, and two pairs of joined struts, held together by a short central tendon, connect the corners to its central area. The joined struts give the model optically more substance, and the behaviour provided pure fun. The model balances on a triangular face, so one strut always points up. If you push back this strut, the tendon connecting it to its joint member slacks off. Once you release it, it springs forward, easily with enough momentum to tilt the model over.



If I use joints again, I make sure I use a hinge joint for the tetrahedron. Two joined eyebolts offer too much freedom of movement, which might contribute to a collapse as well. The structure feels different from most class 1 tensegrities I build, and show a surprising dynamic movement under little external stress.