Calling Ball

This sculpture holds a special place in my heart. It's all tied up with the moment in my life when I realized I wanted to make art for a living.

Calling Ball (2008)
Poplar dowel, roofing nails, twisted nylon masonry twine
33-inch diameter

It's built with sixty rods and one hundred and eighty lengths of string. The whole thing is light and airy, yet sturdy and springy. It's a lot of fun to look at and to play with.

The structure is based on Buckminster Fuller's sculpture "Sixty-Strut Tensegrity Sphere". I was able to reverse-engineer Fuller's sculpture by studying a few photographs and puzzling through it. Once I had the geometry figured out, the rest was straightforward. I fabricated a bundle of struts (wooden rods with nails on the ends), and a collection of tendons (pre-cut lengths of nylon twine with the ends melted to form stoppers) and began making connections. The assembly process was fast and smooth, I was done in a weekend, and just like that, I had a model of Fuller's marvelous sculpture of my own. What a delight!

The making of:

When I first came across "Sixty-Strut Tensegrity Sphere" online. I was blown away. Astounded. Captivated. I couldn't get it out of my mind.

Sixty-Strut Tensegrity Sphere (1979)
Richard Buckminster Fuller
(American, 1895-1983)
Stainless steel and wire 9 ft. diameter

Photo credit unknown. It appears to be taken with the sculpture on exhibit at the Carl Solway Gallery.

I studied all the information I could get on this sculpture, which was scarce. Here's what I found online:

I stared long and hard at the photos of this sculpture. I wanted to see it for myself in real life, get up close, find out how it behaves, how the pieces go together, play with it, get my hands on it.

But even if I contacted the management of the building at UW-Madison where it hangs, bought a plane ticket and flew out there, I'd have to view it from the appropriate distance for the general public. I thought my enthusiasm warranted more than that. What I really wanted was to have Fuller's sculpture for myself, but this is unrealistic. I'm sure UW-Madison likes having it very much.

So, if I can't buy it or lease it, the next best thing is to make my own. As Tom Sachs says, "making it is a way of having it".

The known

From my research I knew that the sculpture was built with repeated three-prism modules. As a self-taught tensegrity maker, I've got this part down. A three-prism module looks like this:

Fuller's sculpture specifically consists of twenty of these modules in a spherical arrangement. That accounts for the sixty struts, (20 x 3 = 60). But on the question of just what type of arrangement, I was stuck.

The unknown

I spent many weeks thinking about how twenty of these things could possibly go together to make a resulting sculpture like Fuller's. But I just couldn't see how to connect them.

For a proper tensegrity, none of the struts should be touching. How could this be achieved here? The above linked article from UW-Madison says the modules are arranged in an "icosahedral form". But, if I merely aligned the triangular bases with the faces of the regular icosahedron, then the ends of adjacent struts would touch each other. You can see this is the case in the below drawing.

So a regular icosahedron wouldn't do at all. I was puzzled and it really troubled me that I couldn't see how it went together. If only I could get a high resolution image, or travel to see the sculpture in person.

But I was determined to discover the secret with the limited resources at hand. I felt this was part of the challenge. If planetary scientists were figuring out the geology of distant worlds using only low resolution images, surely I could figure out how these sticks and string go together.

Finding out the secret

The solution came to me at some point over this past winter holiday. I got to thinking about the chirality of tensegrity, how in many structures the elements go together with a twist. (You can read more about that in another post here).

I thought, what if I twisted the triangular faces of the icosahedron, and separated them a bit so they were partially overlapping? That way, each triangular base would be shifted and and the vertices would all be staggered. Could that be the trick? That had to be the trick! I was sure of it and instantly I could see the whole thing in my mind. Doggone it, even if it wasn't how Fuller's sculpture goes together, it will be how mine goes together, I thought.

Here's an animation of the overlapping triangles as a spherical tiling. It is a metamorphosis from an icosidodecahedron and back again. This is what I saw in my mind's eye. Twenty triangles connected together on the sphere, elbow to elbow.

I wasted no time in starting construction. When I had the struts fabricated and the lengths of the tendons figured out with trial and error, I was off and assembling modules. It took me two sessions over two days and then I had it.

Seeing the sculpture come together was pure magic, and I was elated to see my twisted icosahedron theory be proven right.

Here's a schematic of how the bases of the 3-prisms go together. Note that what would be single tendons if a three-prism module was in isolation, turn into split pairs of tendons when the modules go together. Kind of like a do-si-do.

So, sooner than I could have hoped, I had my own reconstruction of Fuller's sculpture. Just as satisfying, I had discovered the secrets of how it goes together, and the joy of having it for my own.