Geomag Forum

by **Eric** » Wed Dec 02, 2020 10:49 am

Following a discussion in another thread about tetrahelix I discovered a little more about the oloid.
And I think it deserves its own topic.

It started from this post when I didn't know the name of that shape and called it the 2-flying-saucers-crash shape.

: Collision of two flying saucers

Peter then gave us the commonly accepted name 'oloid' (although I still prefer '2-flying-saucers-crash shape' ;-)

)

: Oloid

Chaining oloids I came across this heptagonal wreath:

: Heptagonal wreath with a terrible choice of colors

EDIT : I also played around with Oloids in this post.

After some googling I came to this:
Oloid is one of constant width solids and was discovered by Paul Schatz in 1929
Maths and Physics Club of IIT Bombay article
Nice video by Maker's Muse (Our geomag oloid rolls a little less smoothly ;-)

)
Wikipedia article
Things tagged with 'oloid'
Things tagged with 'constant_width'

If you have a 3D printer it's worth the try ;-)

by **Peter Jepsen** » Fri Dec 04, 2020 3:22 pm

As an exercise I suggest trying to build your Oloid in double size, longer, or both. (double grid size, not two rods end-to-end double)

by **Eric** » Fri Dec 04, 2020 11:39 pm

I can't believe you make me do that again ... Ok let's again collide two flying saucers ;-)

I find it easier to first build the two full decahedrons that are more precisely pentagonal bipyramids (part of the deltahedron and the Johnson solid families) ;-)

And then remove the excess rods to complete the assembly.

: Let's collide those flying saucers

: Double-scale Oloid

See more photos of this one and also my "Yin and yang Oloid" in the Oloid Delirium thread.
See the howto in the instructions forum.

by **Peter Jepsen** » Sat Dec 05, 2020 1:09 pm

Very nice. Now make it longer! Can't do that with the saucers anymore, can you

by **Eric** » Sun Dec 06, 2020 2:38 am

Ok Peter! I have to admit it wasn't as easy as I thought at first glance. It is not a very intuitive shape and it requires a little vision in space to understand how to lengthen it.

So I first came back to scale 1 to understand what we were talking about ;-)

: Scale-1 Oloid - Normal size

: Scale-1 Oloid - Long size

: Scale-1 Oloid - Extra long size

If you ask yourself the question: no! you cannot go beyond the extra long size because the more you lengthen the shape, the more you have to squeeze the pentagonal bipyramids and then the rods no longer connect well to the spheres at both ends of the Oloid (because of the angle).

Have a look at the 'Oloid delirium' thread, I have surprises for you: the twisted Oloid and the angular Oloid :shock: