Beadwork, Polyhedra

Augmented Truncated Dodecahedron J68

A little while ago I wrote about the Beaded Johnson Solids Project set up by Diane Fitzgerald, a project to make all 92 Johnson solids out of beads. I volunteered to make number 68, the Augmented Truncated Dodecahedron. After a lot of time spent making decagons here it is!

BeadMechanics_J68_1

I’ve named the beadwork version Reflecting Pool. In total it’s made from 11 decagons, 1 pentagon, 5 squares and 25 triangles. To give a better idea of the shape here’s an animation of the polyhedron made using Stella4D Pro:

J68

Here’s the net of the beadwork shape before it the final assembly. I think it looks like a series of connected pools, which is where the name Reflecting Pool came from.

BeadMechanics_J68_Net

Before I started joining the beadwork net together I did a trial run with a paper model – fortunately my beadwork skills are better than my papercraft skills!

BeadMechanics_J68_PaperModel

I really like how the shape turned out. The decagons seem quite sensitive to even the small size variations in the beads and so ended up slightly concave rather than as flat as the ones I made initially. However, I really like how they end up looking when joined together.

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I’m tempted to make a plain truncated dodecahedron, with just decagons and triangles, however it might have to wait a while until I manage to make 12 more decagons!

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Beadwork, Polyhedra

Augmented Dodecahedron

Making polyhedra using round beads and polyhedral angle weave is my current favourite bead technique! Here’s an augmented dodecahedron made using 4mm beads:

BeadMechanics_Dodecahedron1

This is a dodecahedron with extra dodecahedra added to each face (augmentation). In theory there should be a slight gap between each neighbouring dodecahedron, but with the beadwork you can merge them together to end up with this shape.

It did require quite a lot of concentration to weave but it was still an enjoyable experiment. I’m definitely going to be trying more shapes like this!

BeadMechanics_Dodecahedron2

 

Beadwork, Polyhedra

Near-Miss Johnson Solids

The Johnson solids are strictly convex polyhedra with regular polyhedra as faces – that is polygons with sides and angles that are all the same. Near-miss Johnson solids however are strictly convex polyhedra that almost have regular polyhedra as faces, but not quite. There are actually a lot of interesting polyhedra that meet this definition. And since they are almost regular you can try making them using same sized beads and let the beadwork distort slightly to make up for the slight differences needed.

Here are a few of them made with illusion cord and 4 mm beads using “polyhedral angle weave” (which is just regular angle weave used to make the various polygons that make up a polyhedron).

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The first one is a truncated triakis tetrahedron, which has 12 pentagon and 4 hexagon faces:

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This was easy to make and only needs 42 beads. It’s fairly small and makes a nice little beaded bead!

The next is a chamfered dodecahedron. This is similar to a truncated icosahedron but with ten more hexagons:

BeadMechanics_JSNearMiss4

This one has 120 beads and works really well. It’s a bit bigger than a truncated icosahedron and looks very round, definitely one of my favourites!

The third is a rectified truncated icosahedron. This is basically a truncated icosahedron with triangles added between all the faces:

BeadMechanics_JSNearMiss6

This one has 180 beads and is less round but is still an interesting shape!

The next is an expanded truncated icosahedron, which is sort of like a truncated icosahedron version of a rhombicosidodecahedron. It has triangle, square, pentagon and hexagon faces:

BeadMechanics_JSNearMiss7

This has a lot more beads – 360 in total – and is much bigger than the others. It was a struggle to keep it looking reasonably symmetric, but the patterns made up by the combination of pentagons or hexagons surrounded by triangles and squares are really quite pretty.

The last one is a snub rectified truncated icosahedron and is like a truncated icosahedron version of a snub dodecahedron. It’s made up from triangles, pentagons and hexagons:

BeadMechanics_JSNearMiss10

This is larger still at 450 beads and does not work well at all! The faces are just too far away from regular to work with identical beads and it just wasn’t possible to get it to be symmetric. Well, not all experiments work! I’ll definitely be making some of the smaller ones again though!

 

Beadwork, Polyhedra

Rhombic Dodecahedron

Here’s a fun shape – a rhombic dodecahedron made from warped hexagons and octagons. I wasn’t sure how well this was going to work, but I really like the way each face looks like a slightly folded square. A rhombic dodecahedron has twelve diamond-shaped faces, so I knew it wouldn’t look completely symmetric and it’s interesting to see how it’s turned out!

Rhombic_Dodecahedron_Vertex_Hyparhedron_Verrier_BeadMechanics

I also really like the colour of these green delicas – I don’t use green very often but glad I did this time! I was also very relieved that inclusion of a few matte delicas (the row of brown beads) did not result in disaster! I’m always a bit wary of matte beads since they seem to break very easily, but treated with a lot of care they worked out well.

I started this about 2 years ago just before a move but it got left forgotten afterwards for most of that time. Decided it was about time to finish it last summer! It’s quite similar to the Hypernova dodecahedron in some ways – both are what I’m going to call vertex-hyparhedra, because they are based on the idea of placing higher-order hypars over the vertices of a polyhedron. I think I’m going to start calling the other beadwork hyparhedra edge-hyparhedra (as they involves putting hypars over the edges), and Erik Demain’s original method face-hyparhedra (as it involves putting hypars over the faces of polyhedra).

Rhombic_Dodecahedron_Vertex_Hyparhedron2_Verrier_BeadMechanics

Whatever it’s called it’s definitely an odd little shape, but I like it!

Beadwork, Polyhedra

The Beaded Johnson Solids Project

The peyote octagon and decagon make it possible to bead a lot of polyhedra. For example here’s a truncated cube – one of the Archimedean solids – made using triangles and octagons:

TruncatedCube_BeadMechanics

It’s a fun shape – I think it looks like it’s made of flowers!

As well as the Archimedean solids it’s also now possible to make all the Johnson solids, and Diane Fitzgerald has set up a project to do just that!

The Johnson solids are all the strictly convex, regular polyhedra that aren’t uniform. A convex polyhedron is one that has no “valleys” on it’s surface, like the truncated cube above. Strictly convex means that flat surfaces formed by polyhedrons don’t count as convex either – so a polyhedron that is essentially a cube with each square face split up into four smaller squares would not be strictly convex, since the larger square made from the four smaller ones would be flat. Regular just means that the polyhedra are made from regular polygons, which have equal angles and sides. A uniform polyhedron is a regular polyhedron that has identical vertices – that is, each vertex is made of the same combination of faces meeting in the same order and at the same angles. The Platonic solids, Archimedean solids, prisms and antiprisms are all uniform convex polyhedra. All the other non-uniform regular convex polyhedra make up the Johnson solids.

There are exactly 92 of these shapes, and they were first listed by Norman Johnson in 1966 in the paper Convex polyhedra with regular faces (Canadian Journal of Mathematics, 18, 169). This list was then proved to be complete shortly afterwards by Vicktor Zalgaller (Convex polyhedra with regular faces, Seminars in Mathematics Volumne 2, V. A. Steklov Mathematical Institute 1966, English translation: Consultants Bureau, 1969). They’re numbered as J1 through to J92, and each has it’s own (often very long!) name. Although there are 92 different shapes they’re all combinations of just triangles, squares, pentagons, hexagons, octagons or decagons!

Diane’s project is a call to beaders internationally to join in making the 92 Johnson solids out of flat peyote shapes, just for the fun of it! Once complete they will be strung in order and be available for display.

If you volunteer for the project you get to pick the shape you want to make (and then give a beadwork name to!) and you’ll get a (free!) copy of the instructions for the basic shapes and a guide on how to make the Johnson solids. It’s a great opportunity to learn some new beading skills! There’s a facebook group for the project here, or you can contact Diane directly for more information.

At the moment more than half the shapes are in progress or complete. Here are some photos of a few of the finished polyhedra!

 

InaHascher_J5_J16

J5 and J16 by Ina Hascher

 

VeePretorius_J13_J59

J13 and J59 by Vee Pretorius

 

MariaCristinaGrifone_J46

J46 by Maria Cristina Grifone

 

DianeFitzgerald_J57

J57 by Diane Fitzgerald

 

NancyJenner_J58

J58 by Nancy Kooyers Jenner

 

CarolRomanoGeraghty_J63

J63 by Carol Romano Geraghty

 

SylviaLamborg_J91

J91 by Sylvia Lambourg

 

GerlindeLenz_J92

J92 by Gerlinde Lenz

They’re all fascinating and beautiful! Here’s the complete set of Johnson Solids, J1 through to J92 in order left to right, then top to bottom. Please join in and bead one!

JohnsonSolids2

 

Beadwork, Polyhedra, Tutorials

Rhombicosidodecahedron Hyparhedron Variation

Here’s an interesting variation on a hyparhedra – a rhombicosidodecahedron which uses both warped squares and hexagons.

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A rhombicosidodecahedron is an expanded dodecahedron with rings of squares and triangles surrounding the pentagon faces. This means that this beaded version can be thought of as an expanded version of Hypernova! Here they are side-by-side:

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As you can see it’s pretty big! It took a lot longer to bead than I thought it would, but I’m very happy with how it turned out.

The idea for this started with a geomag 1.5 scale rhombic hexacontahedron by Rafael Millán, which I came across earlier this year. At about the same time I was working on warped square hyparhedra, and I realised that this polyhedron would be possible as a hyparhedron using a combination of both warped squares and warped hexagons. Essentially it’s a variation on the warped square rhombicosidodecahedron hyparhedron where the three warped squares making up the triangular faces are replaced by a single warped hexagon.

I’ve wandered into this idea before with the truncated tetrahedron hyparhedron – on the left in the photo below is the warped square hyparhedron version and on the right is the variation with the triangular faces replaced with warped hexagons:

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It’s interesting to see that it also works with a larger shape. I’m still working on the plain hyparhedra version of the rhombicosidodecahedron, but it will be great to see them side-by-side when finished too!

This one took too long to create a tutorial, but here’s a layout diagram if you want to attempt it! In total it needs 20 warped hexagons and 60 warped squares. The warped squares sit over the edges of the pentagons, with the peaks and the corners and the valleys meeting at the centre. The diagrams below show the top half of the rhombicosidodecahedron. On the left is the position of one warped square outlined in red – the increases are shown as dashed lines and the peaks marked with circles. On the right a whole set of warped squares is shown around the top of the shape.

The warped hexagons join it all together. They sit at the centres of the triangular faces and are “zipped” to the warped squares. The diagram on the left shows how one warped hexagon joins to one warped square. The diagram on the right shows a set of warped hexagons around the top of the shape.

I made the warped hexagons completely, and then joined the warped sqaures to them. The angles in the square faces are quite tight, so I tried to always start the join towards them and end it at the pentagon side, so there was more space to work. As ever with these shapes, a curved beading needle is essential!

It took me a while to get my head around the shape, but it eventually clicked! Just ask if you have any questions about it!

rhombicosdodec_hypar_var_verrier1

Beadwork, Polyhedra

Five Intersecting Tetrahedra

Earlier this year Diane Fitzgerald posted a geometric challenge: make a beadwork version of the origami model of five intersecting tetrahedra. After many months of work here’s my version!

BeadMechanics_IntersectingTetra2

I’m not the first person to make this – Kris Empting-Obenland gets the credit for that! Her beautiful version has been accepted to this year’s Bridges conference – you can see it in the Bridges 2019 gallery here!

Five intersecting tetrahedra is an interesting compound shape that has some similarities to a dodecahedron. I’m always interested in geometric challenges so I decided to see what I could do. My first attempt was with 30mm bugles, which worked surprisingly well!

BeadMechanics_IntersectingTetra1

If you want to try making one of these I recommend working from a video showing the construction of the origami model, like the one here. However, I definitely recommend using similar colours to those shown in the video – and not what I did, which was mostly similar colours but in a different order which got very confusing!

My next step was to take a few ideas I had been working on following on from my Sunburst dodecahedron, which uses Sue Harle’s tubular diagonal peyote technique.  I realised I could use this technique here to make individual beams for the sides of the tetrahedra, meaning the construction would be very similar to the origami version – and hopefully that it would be easy(ish) to join together. Here’s my first attempt at a tetrahedron using this method:

BeadMechanics_IntersectingTetra_InProgress1

It worked! My next step was to work out the dimensions of the beams so that the compound would work – if the tetrahedra are too small then you can’t interlink them, if they’re too big then it won’t hold its shape. Because the geometry of the beams here is very slightly different to the origami version they need to be a very slightly different size so the model will fit together correctly. So there was a brief interlude from the beadwork for some maths to work out the exact size, which turns out to be a ratio of width to mid-beam length of 1:13.5441. I checked this calculation three times and then asked someone else to check it, as I had nightmares of making 5 tetrahedra that were all slightly too small to fit together!

The next step was to start beading. I spent a lot of time measuring and re-measuring the first few beams to check the size (I’m very glad I invested in some digital calipers a while ago!) but eventually managed to make a full size tetrahedron – 1 down, 4 to go!

BeadMechanics_IntersectingTetra_InProgress2

I decided to use just one colour, which also gave me an excuse to use some Crystal Marea delicas that I’d been wanting to make something with for ages!

The next step was to make the second tetrahedron. This one was easy to assemble around the first, and it seemed like I was making reasonable progress.

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However, experience from the bugle bead version (or rather, experience unpicking many mistakes in the bugle bead version) left me feeling a bit apprehensive when it came to the next tetrahedron – and I ended up leaving the project to languish for a few months.

To try and make it easier to pick up I tried making another bugle bead version – this time all in the same colour. However, this ended up being so difficult it didn’t really help my confidence at all! I decided to just make all the beams for the remaining three tetrahedra then set aside a long weekend to try putting them together. Here are all the pieces ready for the final assembly:

BeadMechanics_IntersectingTetra_InProgress4

I was dreading this bit, so decided to just tack the beams together at the ends with separate thread to make it easy to take apart if (when) I made a mistake. To my surprise though it went together fine – I’d like to think it was all the practice with the bugle bead versions, but I think it might just have been luck! Here’s the initial assembly, before I stitched the beams together properly – it’s a bit of a tangle!

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But it gradually sorted itself out into something more symmetric and geometric!

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At this point it became clear that the beams were the right size – which was a huge relief! Then it was just a matter of stitching in the last few threads to finish the piece and complete the challenge!

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And this definitely was a challenge! But I’m glad I attempted it as it pushed me to develop a few new construction ideas, and even though at times failure felt inevitable I did enjoy the process! Also, at about 65g of delicas this is easily the largest piece I’ve ever made!

And as for that second bugle bead version? I did eventually manage to get it to work – and it’s now one of my favourite pieces!

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