Bigger things

I recycled some of the struts I used for my geodesic dome experiment. With about 90 cm strut length 6 strut models of tetrahedron and icosahedron just so fit through my front door, my ambitions certainly outgrow my available work space indoors. 23 squared still hangs in a modestly visible spot from a tree, the storms of the last few days haven't affected it.

I have no idea about the effect sunlight will produce - typical Melbourne weathers meant grey skies since I installed it. But I found a perfectly suited spot for the next installation, an icosahedron, again with some parts of the struts spray painted.

The rain seemed to have stretched the tendons, I twisted some struts to increase the overall tension. I hope my idea about visibility works out, at night it's basically invisible. Hope the sun comes back to Melbourne soon.

Do or die

2012 started suboptimal when it comes to market appearances. Without the more complex sculptures, there's less eye catchers on the table. Who cares, I'm basically trying to sell art, so can't really analyse my success in business terms.

On the other hand, the lack of sales means I can come up with new projects what to do with tiny supply of rods I still have at my disposal. The source has dried out, just after I got a better idea how to work with the slightly heavier material than usual.

However, I experimented with a different topology for the tendons in the corner. Instead of connecting the tendons between neighbouring struts, I used a little ring to join them in the center of the corner. The struts have now an individual degree of lateral movement, and the cube happily balances on each corner. I also build an octahedron and the Vector Equilibrium in star formation instead of using loops for the corner.

As I enjoyed the different movement patterns with centrally joined corners, I went a bit bigger, attempting a hanging installation for outdoors. It survived already some strong gusts in its test location, it behaves quite nicely in windy conditions. The structure tends to rotate slightly out of the wind pressure, and doesn't swing itself up easily.

Octoids

I haven't been that busy during a week with building tensegrities ever, and I enjoyed it thoroughly. I needed models I could transport without a car. It will be lots of fun to find out how practical my idea of transport will be tomorrow, unicycling with a backpack from which twenty or so tensegrity structures dangle....

Besides a set of octoids, octahedra in which colours enhance aspects of their structure, I build a number of colourful icosahedra. I hope I can source more of the material I used for the latest icosa builds, it saved me lots of work. Doing the computer related things, like preparing and uploading the slideshow turned out much less pleasurable. Nevertheless, all is prepared for an interesting market day tomorrow, including the update of the market datea for the first three month of 2012.

The next season

Many things happened since I last had a stall at the Rose Street Market, most unfortunately, my car got totalled so I now face the challenge to transport enough models either on PT or on a unicycle.

As most of my toy octahedra were gone, I prepared the components for another batch of octoids, spending lots of time on sawing, cutting and a bit of spray painting. Luckily, I didn't forget how to build tensegrities, determined to produce enough portable material for next sunday's market I got into a bit of a rush - six octahedra, one icosahedron and one cube provide the first yield of two days work.

By chance I came up with a new colour combination for square struts, which works amazingly well. I might need to prepare another batch of struts to use up all the coloured ones I have now, and getting the photo and documenting job done.

I nearly forgot the joy of bringing tensegrities to life, especially those with unique looks.

Detour into the basics

I detected through a comment the work of George Mokray - he build a set of A and B quanta modules that connect via magnets, and form a tetrahedron and an octahedron, which then join together to a cube. I spend some time investigating his suggestion to build tensegrity quanta modules, and simply need to keep track of some important experiences I gained in this process.

Tetrahedron split into four volumetric quarters, bottom quarter split into 6 A-Quanta modules

My spatial imagination improved while working on my tensegrity structures, but I still have trouble conceptualising a 3d object from a 2d still image. Initially, I was unaware that the four quarters were identical, and that the same applied for the A-quantas - there's only one set of edge lengths which can be build in two orientations.

A Class-2 tensegrity tetrahedron requires only four struts, two joints and seven tendons. As the a-quanta module is an irregular tetrahedron, there are two different strut length and seven different tendon lengths that need to be calculated (or experimentally derived). Symmetry brings a lot of stability and balance two class-1 tensegrities, irregular objects belong to uncharted territory.

Nevertheless, I used my copy of Fuller's Synergetics to refresh my knowledge, and started creating a CAD file to have some plans with precise measurements. I plan to do some 3d printing in the future, which means I better familiarise myself with CAD software. And potentially I could design single struts with a bend, instead of using two struts and a join.

Besides building an irregular tetrahedron as Class-2 tensegrity, the challenge to join many of them remains tricky. George used magnets in the faces to link the modules together - magnetic polarity will still require face bonding. However, depending on the design of the strut end, three magnets could be installed at each end.

The next steps will be designing the strut ends to easily attach tendons, and deciding how much curvature I will use. Building has to wait for a while- first I will have to set up the printing environment,  which hopefully will solve of the technical problems I have with OpenSCAD.

Revisited

Red Star (Intertwined tensegrity tetrahedra)

I revisited my attempts to combine tetrahedra to build a tensegrity representation of the merkaba. Red Star comes so far closest to joining two tetrahedra in this fashion, yet I had to take two different sizes. The tendons of the red tetra are suspended from the struts of the larger one, it can vibrate while the outer structure is extremely solid.

Red Star

The tendons of the larger tetra connect to each other, instead of directly from strut to strut. I haven't tried out this way of connecting a corner with elastic string, with nylon it works really well, and is optically very appealing.

Merkaba (Tensegrity octahedron with 8 tensuls attached to form two tetrahedra)

With 36 sticks the sculpture Merkaba offered initially hardly any depth to it, as all struts had the same colour. I rebuild the structure using a green octahedron, and using bicolour struts for one of the surrounding tetrahedra. The model balances on each of its eight tetrahedral corners, and folds down along the axis connecting opposite corners of the octahedron.

Merkaba

Exploring other things...

I guess I'll need some more practise in producing videos, there's still some unclear instructions and a couple of hang-ups in it. I still hope for decent light conditions in my improvised video studio to shoot the how-tos for icosahedron and dodecahedron, with the potential to redo the intro part as well. However, this video gives you an impression how fast models can be build: Only seven minutes show what's happening between the first connection and last connections being made, without time lapse.