Beaded machines

Trefoil Knot Kaleidocycle

A while ago I found an interesting paper about rotating rings of tetrahedra (aka kaleidocycles) by Jean Pedersen¹. Apart from some great instructions on how to make them by braiding two strips of paper together it also mentions that with enough tetrahedra, a kaleidocycle can be tied into a knot and still rotate.

So of course I had to try this! The paper says that the minimum number of tetrahedra required is 22, which is quite a lot. I decided to make them out of bugle beads to test the idea. I made a long strip of them using right angle weave (although in this case the angles aren’t right-angles) and illusion cord . When I had enough tetrahedra I tied the strip into a trefoil knot – this is just an overhand knot with the ends joined together. The completed kaleidocycle looks like a bit like 3 normal kaleidocycle merged together:

TrefoilKnotKaleidocycle_BeadMechanics_1

Now for the moment of truth – does it rotate properly?

The answer: yes! It took a few tries to work out how to get it to turn properly, but it’s great fun to play with. Here’s a video:

I think this is my favourite kaleidocycle so far! I want to make a peyote tetrahedra version, but the 88 triangles needed might be going to take me a while!

 

¹The paper is “Braided Rotating Rings”, Jean J. Pedersen (The Mathematical Gazette, 62, 1978).

Beaded machines, Beadwork

Decagonal Kaleidocycle

Last week I finished my second beaded kaleidocycle – a half-closed decagonal kaleidocycle!

decagonal_kaleidocycle_beadmechanics_7

It’s made in a similar way to my last kaleidocycle, except that this time the tetrahedra aren’t regular – some of the sides are different lengths. I based the shape of them on a paper model of a half-closed decagonal kaleidocycle from www.korthalsaltes.com – an amazing website with lots of kaleidocycle models!

Here’s a video of it in action:

The “decagonal” part of the name means it’s made of ten tetrahedra, the “half-closed” part means that some the faces meet with no gap in the centre – or at least they’re supposed to! The beaded version ends up with small gaps in the centre of these faces since the beadwork tetrahedra are only an approximation of the exact shapes.

Using tetrahedra with different length sides means that the different faces you see as it turns are all different shapes – which is pretty neat!

decagonal_kaleidocycle_beadmechanics_11

The colours didn’t quite turn out how I expected them to, with one side of the kaleidocycle entirely blue – I designed the pattern on just one tetrahedra and didn’t quite manage to predict how it would all fit together. At least now I have a complete model that will help with the next one!

I’m very happy with with it as it is though – I was quite nervous as I was making it that it wouldn’t turn properly, so I’m very happy it rotates as it should! Definitely going to be making more of these!

decagonal_kaleidocycle_beadmechanics_9

Beaded machines, Beadwork

Folding Cube

So I finally managed to finish the new machine I was working on! This time it’s not a kaleidocycle but a folding cube made using cubic right angle weave. Here’s a video:

I can’t find out if these cubes have a technical name, but they seem to generally be known as magic folding cubes. They’re actually quite similar to kaleidocycles, since they’re  a ring of eight linked cubes that can be rotated around back to the original starting point. However, they’re also very different since they alternately form two larger cubes during this rotation. I made the faces on each of these bigger cubes distinct – one is just the plain cubic right angle weave surface:

cube2_verrier

and the other has crystals embedded in it:

cube1_verrier

Each individual cube is a 4 by 4 block of cubic right angle weave, with a 2 by 2 gap for the crystals on three sides. Each of these cubes are joined to the two neighbouring cubes using modified right angle weave to make a hinge. I used size B nymo, size 11 seed beads and 4mm crystals (although 3mm or a flatter bead might have been better as the 4mm is just slight too big). I also found a curved beading needle a big help for some of the later rows!

If you want to try making one then I recommend making a paper model first for the hinge pattern – there are a lot of websites with instructions for making paper versions and having a model really helped a lot when I was putting it together.

Eventually I’d like to try making one out of 8 stellar octangula (a polyhedron that looks like two intersecting tetrahedra), since they have the same layout of vertices as a cube so could be fitted together in a similar way. Worked out that I’d need to make 192 triangles to do this though – might take a while!

Beaded machines, Beadwork

Kaleidocycles

I’ve been making slow progress on beadwork over the summer, but I have had a bit of time to learn more about kaleidocycles and plan out my next project! Unfortunately I haven’t quite finished the current project (more on that soon) but meanwhile I realised I only ever posted a video of my first kaleidocycle and not any photos, so here it is in more detail!

kaleidocycle1_beadmechanics

And here’s the opposite set of faces:

kaleidocycle2_beadmechanics

Finally, here’s a view from the side:

kaleidocycle3_beadmechanics

Can’t wait to start the next one!