Knex Natural Dodecahedron

This is the famed Platonic solid made from standard K"nex parts. The parts all fit together without bending or stress. That is why I call it Natural.

The hubs are based upon a K'nex star. The star is made from 16 2-con and 16 16-mm rods. It can transform from an eight pointed star to a bracelet. Limiting the connectors to six makes a sturdy pseudo-hexagonal structure. Replacing three 2-con with 3-con allows interconnection.

30 rods 54-mm or larger all the same.

120 16-mm rods.

60 2-conectors angled.

60 3-con

Twenty hubs are made from the parts. Each has 3 2-con , 3 3-con and 6 16-mm rods. It is important to have the same chirality in all the hubs. That is they all go clockwise or anti-clockwise. This is important to keep the model from becoming lopsided.

With five hubs and five long rods, make a flat pentagon. All the 2-con point up. Attach five more long rods to the open 3-con slots. Using one of the edges of this pentagon, construct another pentagon. Construct four more pentagons using one of the edges of the original pentagon each.

Five more pentagons are built on top of the first six. The last pentagon will happen.

It can be hung up as a decoration. Using a string through one connector home works, but stresses a larger model. Best is to hang it from the top five connectors. First hang a small ring or S-hook from a string. Tie a double arm length of string to the ring. Thread the string through each connector on top and then through the ring. Adjust the looped strings to be about the same length as the pentagons are wide. Tie the string to the ring. Trim excess string. The continuous loop of string will make leveling easier.

If the dodecahedron is small enough, you can play catch with it as it is sturdy enough.

Putting two fingers in opposite hubs allows it to be spun.

A large model may be built by using 393-mm steel rods. This is a build for those who have 30 steel rods in their inventory. I only have one.

Using mathematical transformations, it can be converted into an icosahedron. But that is another build.

The hubs have chirality. That is they are either left handed or right handed. I made a dodecahedron of each and mated them. The picture is a baby dodecahedron being born. When it grows up I can take it apart to add the parts to my inventory.

Note: mating them is difficult and gestation takes a year. This is only suggested for those builders who live on a farm. (grin)