Originally published at: https://boingboing.net/2020/01/10/watch-these-cool-sphericons-ro.html

…

# Watch these cool sphericons roll across a table

I once made one of the equilateral triangle ones on my wood lathe. I wood-glued 2 pieces of wood together with a piece of paper bag in between, which gave a bond that was strong enough for turning, but then easy enough to split afterwards. I turned the cone and then split the pieces, cleaned up the faces, rotated, glued, sanded, and finished. IIRC, I made a hollow in the center and added a couple hex nuts during glue-up to add some heft.

It was a relatively straightforward and fun project and yielded an intriguing and satisfying object. I think I gave that one to my dad. I kinda want to try one of the more complicated ones now (the equilateral cone was easy for a woodturning novice because as long as you’ve got straight edges and keep the angle from the base to the side correct, you can’t really screw up the shape).

If they were doing a *The Prisoner* remake, use one of these for Rover’s ground motion.

Two words: Cat Toy.

Not sure what’s so awesome about a drunk wheel.

(I kid, I kid - it’s really cool!)

re the cone rolling, the presenter says: “It can’t continuously roll, it just stops. And this is true for all odd-sided permutations.”

Yet he provides no proof… I would think this would be feasible to prove…

This is going to bug me.

Agreed. Neither can a sphere or wheel on a level flat surface, due to friction. It certainly looks like the spheroids would keep up with an equivalent wheel.

Ah, I found a site enumerating the variations and the statement would appear to be true as follows. The sphericons start as polygons rotated about an axis. With polygons of odd-numbered sides that rotation generates a “flat” circle at the bottom. That leaves the rotations inevitably ending up at some point on a flat spot made up of a semicircle.

I’m sure you could write all of this as a group, but I’m happy with that answer.

Those were really wacky, and really cool.

This topic was automatically closed after 5 days. New replies are no longer allowed.