Sunday, 10 August 2008

270 Sonobe unit ball

This is my guide/show into how to make a 270 unit Sonobe Epcot ball.

First start with 270 sonobe units. This is the easy part believe me. That said, folding 270 of these things took me a long time even while I was spending long periods in hotel rooms on business with little else to do.

Lots of sonobe units

That done, assemble the first face. As the ball consists of hexagon faces surrounding pentagons I found it easier to start with a pentagon face made from 5 units.

Sonobe ball, stage one.

Now to build up the hexagons around it. the biggest problem is these are not flat faces so lots of squinting is involved in trying to work out where each face starts.

270 Unit Sonobe unit Epcot ball

After the pentagon face, you now need to start using 6 units per face to create the hexagons. The picture below shows what this will look like, although this is not a 'true' face as its using units from the pentagon below. Add another layer of units, until the initial pentagon is surrounded by hexagon faces.

Now the only way to describe the rest is to show the finished result.

ecpotfaces

This badly edited image shows a couple of hexagons surrounding a pentagon face. In order to get a sense of where each face goes I've used red dots to mark the centers of the faces. The important thing to remember, is from the center of one pentagon face to the center of the next pentagon face there should be two hexagon centers (indicated by red dots) in a straight line between the peaks.

The finished product should look a little like this.

270 unit Sonobe unit ball

Hope that helped someone. I spent a looong time trying to work that out.

5 comments:

Unknown said...

Thank you so much! I was actually able to construct this model based on your instructions. Any idea what this shape is called? I'm thinking it's a truncated icosahedron but I'm not quite sure.

Stu Price (@sxpmaths) said...

The underlying shape composed of pentagons and hexagons is a truncated icosahedron. The sonobe units add a number of peaks to each face, and so this is usually known as a stellated truncated icosahedron.

I wish I had the patience to build one!

Unknown said...

could you send these instruction with more detail to my gmail. Bryanna.l.Thornton@gmail.com

Unknown said...

Its called a Epcot ball. And this is the first instruction thing on it so thx.

Unknown said...

This is not the Truncated Icoscahedron, that is the 90 sonobe unit ball