I Like My Icosahedra Truncated! (Patreon)

I can't stay away from geometric shapes!  

You may recall the cube, dodecahedron, and others that went together with interior brackets and exterior bolts.  Well, those weren't big enough!  This polyhedron uses the same hexagonal and pentagonal pieces bolted together to make a truncated icosahedron, which is probably most familiar as the classic soccer ball design.

So, let's cover what pieces we need for this:

* 20 hexagons

* 12 pentagons

* 60 corner brackets

* 180 bolts

Since each vertex of the shape has one pentagon and two hexagons we only need one type of corner bracket!

Oh, bolts!  So, after putting this thing together, I ended up designing a flat version of the bolt as an alternative, and printed 180 of those instead.  They have the same thread as the regular bolt, but a thin exterior instead, and a small hexagonal hole in the centre.  The hole is intended to fit a 3mm hex key, but it's not actually needed at all - you can still just tighten the flat bolts by hand since the outside is still textured and easy to grip.  These new flat bolts will work just fine with the previous bolted polyhedron designs, too.

Right, so, once we have all the bits printed, putting it together is not difficult.  Just remember that each vertex has one pentagon and two hexagons, and all will work out fine.  

Now, you may have guessed that the corner bracket piece needs to sit in a particular orientation - the angles between the hexagonal sides is not the same as the angle between the hexagons and pentagons.  Fortunately, you'll see a little notch on one of the three bolt holes on the bracket - this is the bolt hole that belongs to the pentagonal face.  But if you get it wrong you'll know very quickly anyway, since the faces won't line up :)

Printing Tips

All these pieces are designed for straightforward printing - nothing here should be tricky!  The faces print inside-down, and the bolts print head-down.  The brackets have a flat side that goes against the bed.  Here's a pic of all that:

File Location

This one gets its own folder on dropbox, rather than being put under the bolted cube.  You'll find it under: 

811 Bolted Truncated Icosahedron

The flat bolt has also been put into the existing Bolted Cube folders, too, wherever the standard bolt file is found.

Final Thoughts

There's something really great about putting together these kinds of things that have such precise angles, and having it just work.  3D printing is great like that :)  

There's another polyhedron on the way, though it remains to be seen how long it'll take to get all the pieces printed in between other things!  It'll quite possibly end up fairly large, too...

Have fun!

xoxo

Sven.