Archimedean Ball

Actually, it's a trucated icosidodecahedron, but I opted for a more poetic and rather loose choice of name instead.  It's huge!

Hey there, wonderful people!  One last one before the clock ticks over from the 31st to the 1st, and it's a big polyhedron.  I'm not sure how these things keep getting bigger and bigger, but here we are!  I remember not long ago being concerned that the truncated icosahedron was too big.  And the rhombic triacontahedron.  Family favourites, I know, but they're not small.  And now there's this thing!

This one is a bit of a commitment to construct.  Those ten-sided faces are about 180mm across on their own!  Of course, these things keep getting bigger because I'm keeping the edge length the same in all of them, so a decagon is bound to be huge.  There are only six different parts, but we need a lot of them:

* 12 decagonal panels

* 20 hexagonal panels

* 30 square panels

* 60 x 2 corner pieces = 120 in total

* 360 bolts

As before, either the regular or flat bolts will be fine.  Oh, you might notice that the square panel is actually remodeled.  The old one had a different hexagonal pattern on it to the newer pieces, so I reworked it to be consistent.

So, assembly!  Here are some hints:

* The corner pieces have indicators on each hole for what panel they match to.  A square cut for the square piece, a round cut for the decagon, and the remaining unmarked hole goes to the hexagon.  This can help when trying to work out which of the two mirrored connectors you need at a given vertex.

* The two types of corners alternate around each of the faces.

* Flexing these forms can easily loosen the bolts - the hazards of plastic!  I've considered using a glue and making it more permanent, but haven't tried it yet... it would also mean I need somewhere to keep this thing in its assembled form :)

Printing Tips

In terms of orientation, the parts are printed as shown in the photo earlier in this post.  The bolts are head down as usual, the panels are flat-side-down, and the two corner pieces sit on their flat bases as you'd expect.

You'll want to make sure the pieces don't warp, but beyond that it should be pretty resilient to printing issues.  The bolts and corners have a reasonable amount of tolerance and should work pretty well regardless of printer settings.

The biggest thing to consider with this is the logistics - there are a lot of pieces, and it'll take a fair amount of filament! 

File Location

This one's on dropbox under 808 Archimedean Ball

Final Thoughts

Of all the polyhedra to date, it is no suprise that this one was the most fun to build up.  I think it probably pushes the boundaries of what's sensible in terms of this kind of bolted vertex construction, too.  It would be cool to use similar techniques to facilitate construction from other materials, though.  Gingerbread polyhedra?  Maybe not :P

Happy new month! :D

xoxo

Sven.