[MOC] Truncated icosahedron

[SecondHandLego]

The geometrical shape of this ball is called truncated icosahedron, but you may also know it as a football/soccer ball or bucky ball. The ball is not very strong. It holds together pretty well, but it cannot take a lot of stress. It even changes shape somewhat under it's own weight. My plan was to make a ball with a mechanism inside to make it roll, but this ball is not strong enough for that. However, since I like the looks of it and since it demonstrates the structure of the truncated icosahedron quite well, I decided to post it.

I have been puzzling on a stronger design of the hexagons and pentagons but haven't found something fully satisfying (see this webpage). All help is welcome. On Rebrickable someone suggested to 3D print the hexagons, but that is not really my thing.

More pictures and the design (in Ldraw) on this webpage.

 

 

 

Edited November 28, 2018 by SecondHandLego

[pagicence]

How about trying with some cross braces inside. Instead of a 3713 technic bush on 5L axle that holds 2 shapes (hexagons and pentagons) together, put something like 32013 Axle and Pin Connector or 32039 Axle Connector with Axle Hole on opposite sides and connect them with some long axles. Maybe a few of these can help the ball hold its shape.

Edited November 28, 2018 by pagicence

[SecondHandLego]

9 minutes ago, pagicence said:

How about trying with some cross braces inside. Instead of a 3713 technic bush on 5L axle that holds 2 shapes (hexagons and pentagons) together, put something like 32013 Axle and Pin Connector or 32039 Axle Connector with Axle Hole on opposite sides and connect them with some long axles. Maybe a few of these can help the ball hold its shape.

Thank you for the suggestion Pagicence! I'm not sure I understand you correctly but if I do then it will not work. It is not possible to connect opposite sides of a hexagon because the distance between them is not a round number of holes. It does work for opposite corners and non-opposing sides. Like this

The far-right solution gives some strength but depending on how you put pressure on it, it does not always hold its shape. The other two are much stronger, but it is harder to add the hinges to the edges of those hexagons to connect them to others (this is basically due to the face that the pinholes on either side of each spoke become useless).

If you meant to make stronger hinges between the hexagons, then that will not solve the main problem. I tried that, but with the current design the hinges hold: hey do not change shape nor fall apart. Of course, it could be that when the hexagons are stronger then that means more stress on the hinges between the hexagons, which in turn might mean they do need reinforcement