I bought Tony Wright’s GF last fall but didn’t have a chance to use it due to a bit of spousal paranoia (plus I could just use the one at work), so I’m happy to report that it survived the move to Austin and is running great. No smoke in the house at all, wife is happy.
I finally got a chance to try something I’ve been thinking about for a while. Previously I’d made an icosahedron and a dodecahedron (20- and 12-sided polyhedra), and I was curious how they’d work as spheres by rounding the edges. Then it hit me that since they’re duals of each other (one has its vertices where the other’s faces are and vice-versa), the edges are perpendicular. That means we can make a composite of both shapes, with the edges notched and slotted together. After a whole lot of futzing around trying to remember how to Inkscape then only about ten minutes cutting but then a lot of figuring out how to put it together, here it is!
It’s a deltoidal hexecontahedron, says Wikipedia, 60 kite-shaped faces. It uses 30 each of the short and long edge pieces, 20 triangle connectors, and 12 of the pentagonal connectors. I used Woodpeckers 3 mm Baltic Birch, so the slots are tuned to that, 2.9 mm at the mouth and 2.85 mm at the back. I did my previous shapes in Proofgrade Maple and 3.0 mm slots gave a good fit.
I originally tried to put this together by building the icosahedron first then the dodecahedron on top of it and snugging it together but I couldn’t get the edge pieces flush with each other. I need some kind of L-shaped thing I could poke through to pull from the other side…? Can’t think of what I could use for that. So instead I paired up the long and short edge pieces first then built up the shape as loosely as possible and snugged it all together once everything was in place, a bit at a time all the way around. If you tighten it up as you build it’s impossible to get the last pieces in.
Playing around with the pieces I also found you can tile the sphere in a slightly different way, with just short edges (after running off 30 more of them):
This one’s called a rhombic triacontahedron, 30 diamond-shaped faces. The triangular and pentagonal connectors are arranged in the same way and the edges go between them without any crossing. The short edge piece isn’t exactly the right angle–should bend by 36 degrees instead of 44, if I recall?–but it’s close enough it works.
You could make your connectors longer, and then add a triple of 60 deltoids, and why stop there? Chances are you could keep making shapes that fit the voids and your model to get larger and larger.
If my GF weren’t in Seattle at the moment I’d probably have already tried it.
The added bit, sits on the flat sides of the triangle and pentagon connectors:
And finally: My first run of those edge pieces were too snug for the plywood we’re using now so I had to run it again with the slot a little wider. I can’t throw anything away without seeing if it has a use, so I discovered you can make a ring out of them:
I remember seeing that last year, skimmed over it to get the concept and I’ve been meaning to go back and fill in the details. Thanks for the reminder! I don’t think it would help me much here because I’m cutting the pieces out of scrap plywood, uploading just the individual shapes then duplicating and arranging them in the preview. (And wow, the preview is way more accurate than the last time I used it. Thank you Glowforge!) But if I wind up making full sheet layouts I’ll definitely use this so I can tweak the fit without having to rebuild the entire thing!
It’s been way too long since I’ve had a chance to play with the laser toy.
