Icosahedron v3: More available – and an IABSE Future of Design Finalist

The third version of the icosahedron moves towards a more typical size, but puts its complexity in different places to make it more available and accessible for someone who wanted to build their own. All the geometric complexity (including the precious ‘compass walk’ for marking out the locations of the magnets on the wooden spheres for the nodes, and the end details of the rods) is taken into the computer, and output as a 3D print. You can see the whole icosahedron here and the individual nodes here. For both, user: Rudolf; password: Laban.

These 3D prints can be ordered from any 3D print shop with ease – marketplaces like 3Dhubs provided a good place to start, so in depth understanding of 3D printing is eliminated. The icosahedron has been reduced to a similar level of complexity in construction as a piece of flat pack furniture.

The ‘noding out’ of forces in the nodes, and brittleness of the magnets limiting the force on each of the nodes, means a clear resin – an unusual choice for structural components due to its brittleness – works well. The resin’s translucency reveals the magnets nicely and its detailed prints and small layer thicknesses reduces the required tolerances, as well as producing a beautiful, and nearly imperceptible ‘grain’ to the nodes as the layers reach the top of the sphere. Unfortunately, the tolerances are not small enough to create an acceptable interference fit with the magnets, the icosahedron needs some of its magnets glued in place.

Drying the glue attaching the rod end connections to the rods – what else would such a chair have been designed for?

Rod with glued attachment onto a flat end and magnet (a true interference fit in the fitting, no glue needed, it just relies on the expansion of the attachment)

3D printed node with magnets inserted

3D printed node, rods and rod end attachments forming part of the constructed icosahedron

Other improvements have been made: most noticeably a change in the balancing system for the icosahedron, with the ‘feet’ of previous models replaced with extremely fine thread, a magnet and a steel sphere. This change has been a great step forward for, perhaps surprising, reasons:

  • the icosahedron is more platonic as the threads do not ‘read’ at any distance
  • the new system isn’t immediately perceptible, giving a sense of magic until this small puzzle about how the icoshedron stands up is solved
  • they reduce the length of the package needed to carry the icosahedron by about 300mm, making it easier to fit into small cars
  • the strings make it easier for the icosahedron to adjust to slightly non-flat surfaces with ease

The constructed icosedhedron, note the new balancing system at the base

Constructing the v3 icosahedron

Deconstructing the v3 icosahedron

Another change has been attaching each of the nodes directly to a rod, trying to attach in places where tension will be present (some of the forces are larger due to the change in stability system). The nodes at each corner of the ‘table place’ have been attached to the horizontal rod that defines the side of the door plane, carrying the tension across a glued joint, rather than a more brittle magnet. This attachment also stops stray nodes running across the floor when the icosahedron is collapsed! The pre-attachment of the nodes makes construction of the icosahedron a little easier.

This icosahedron was provided with an ultimate test of its portability – I took it on the plane to Edinburgh to present in the IABSE Future of Design Competition as a finalist – the icosahedron behaved perfectly, surviving the trip, coming together at the end of the lunch break and collapsing (when I hit it hard) mid-presentation! This felt quite daring at the time! It was beaten by some really fantastic work on pre-cast concrete joints inspired by traditional Korean joinery in my half of the presenters – but I was really pleased just to show the icosahedron to other engineers, despite it really being a bit of fun – special thanks go to Eva MacNamara at Expedition for reviewing and helping me improve my entry, as well as pointing the icosahedron in my direction in the first place. My entry paper is here: David Hewlett Laban Dance Icosahedron IABSE Future of Design 2018.

Following its trip to Edinburgh, the icosahedron was handed over to the Keep Fit Association at a small training session.

v3 Icosahedron with the Keep Fit Association


Leave a Reply