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I Like My Icosahedra Truncated!
🕑 Added 2020-07-20 07:55:23 +0000 UTCI 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.
Comments
Clockspring3D
That's really cool! The downside, though, would be sensitivity to printer settings, since different machines and slicing produce slightly different results. The regular bolts avoid that problem entirely, but they do tend to come loose when it's handled... I'm occasionally tempted to just glue them in there :) Actually, just a PVA glue might work, and be removable with later soaking... hmm....
Random thought: what about an alternative to threaded bolt/corner like this? https://twitter.com/dddpworld/status/1285728077604102144 I don't know if the locking pin would always be needed, but it would be one way to have a super solid final assembly.
Clockspring3D
Oh, yes, he got in touch and mentioned you! And yeah, this thing really could be scaled up - bolts are good like that. How big are you thinking?... đ
In theory, you could scale this up right? like a lot? I have a large Delta... hmm. Dude I swear all I print is your stuff. It feels like you're blowing up here a little. Did you see "Edge of Tech's" video? He mentions you and that he signed up because of the posts I made on Twitter I guess. It's pretty cool.
Clockspring3D
I'll be waiting to see what filaments you use - you always have cool colours!
Clockspring3D
Dooo iiiit! đ
Todd Coello
Maybe I'll start Tuesday
Todd Coello
I really need to print one of these.
Cathy O'Malley
On my wish list
