Tag: structure

Coding structure with threads

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One of the most inspiring things we heard from Leslie Downs (our Advisor on textile innovation) was about the way he manufactures high specification structures for aerospace engineering by weaving on ordinary looms, sometime even hand looms for their flexibility. It turns out that some of these techniques are also possible with tablet weaving: I came across this mysterious diagram in ‘Byways in Handweaving’ by Mary Meigs Atwater:

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The text doesn’t really go into much detail about what you can do with “Icelandic double weave”, nor is there much information online that I could find, so I had a play. Normally you weave tablets by rotating the cards quarter turns and using the shed between the top/bottom sides of the cards with them straight. With this technique you rotate quarter turns back and forward from the orientation in the diagram instead, and use two separate wefts for the top and the bottom sheds. This results in two separate fabrics woven at the same time which can be reattached by going back to normal weaving, or crossed over like this:

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This technique is very versatile and results in strong structures. It’s possible for example to connect the weaves along the edges and create long tubes or weave more than two layers attached in different ways. In this way, weaving is an ancient 3D printing process that converts code into structure (and only produces biodegradable waste).

There are some things that you can only do with tablet weaving. As the ‘loom’ as such is just a disconnected pack of cards it’s possible to reorganise it as you go along, for example if you use two wefts and split the weave in half, you get two separate fabrics which can be rejoined later on – they don’t even need to be connected in the same way, I tried crossing them over here – which seemed to work easily enough:

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With the use of four wefts you can even do a double layer weave at the same time as a split like this to create more complex structures, I had a go at that but I ended up with my threads in a mess and accidentally attached the two layers by mistake – I need more practice, and possibly using more than 10 cards would help too.

You can also turn corners with tablet weaving, my first attempt at that wasn’t so great as I found it really difficult to maintain the tension and lost count of my wefts, but you do this by simply gradually adding extra wefts to one side of the weaving. I attempted a full “u-turn”, shown here after some smaller double weave sections:

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It would be interesting to think about how to add these structural modifications to the current tablet language. They all involve adding/removing wefts or skipping warp threads with wefts – notating this is probably fairly simple, but modelling the results would be very challenging indeed, if it’s even possible.

Coding with threads: Frame loom

After writing the 4 shaft loom simulation the next job was to try weaving the structures with real threads. Would I be able to replicate the predicted patterns and structures? Ellen warned me that the meander weave would result in unstable fabric, but it would depend on the nature of the material used so was worth trying. Originally I planned to warp up the Harris loom but I need to work up to that as it’s a big and complex job, so I quickly built a frame loom with some bits of wood and nails at 5mm intervals to hold the warp in place.

A simple frame loom

Here you can see it set up with the all important first ‘shed’ (name given to the gap between subsets of warp theads), which defines the order of the threads. I packed the warp too tightly and messily so this was important – luckily as the yarn colours alternate so it made it easy to make.

'sleying' the warp

Here I’m sleying the shafts using threads to pick up the warp as defined by the simulation toggle buttons. The threads (which form heddles) are tied on to wooden poles which are pulled in different combinations during weaving. This is the approach we saw on the warp weighted looms in Copenhagen, I’m not sure if it’s usually used on frame looms – it was cumbersome but much faster than counting threads manually each time. It’s important to use thinner threads than the warp, but you need to put quite a bit of tension on them so they need to be strong. There is something very appropriate in the context of this project about coding threads with threads in this way.

Four shafts set up ready to start

Here it is finished and ready to start weaving. I numbered the shafts with pencil but it’s actually very obvious based on the order they are attached so I never used them. Following the lift plan from the simulation was quite easy, thinking about the pattern more than the combinations of numbers – as I went on I could tell where I was based on the nature of the shed, keeping an eye on the rhythm of the warp threads picked up. Also the parts where I need to lift 3 and leave 1 was really tricky – not helped by the fact that the resulting weft was difficult to see at that point.

Picking up shaft 4

In relation to livecoding, I was surprised to the extent that improvisation is required when weaving even based on a predefined pattern. There is a lot of reasoning required in response to issues of structure that cannot be defined ahead of time. You need to respond to the interactions of the materials and the loom itself, the most obvious problem you need to think about and solve ‘live’ is the selvedge – the edges of the fabric. In order to keep the weave from falling apart you need to ‘tweak’ the first and last warp thread based on which weft yarn colour thread you are using. The different weft threads also need to go over/under each other in a suitable manner which interacts with this. This will be important to include in the simulation properly, but this will only give an early indication of problematic decisions, rather than a failsafe solution.

Meander closeup

Here’s a closeup of the meander pattern compared to the simulation. The yarn is cheap and a bit fuzzy, but hopefully you can see the structure – the differences are interesting. I’m not sure how this will distort further when I remove it from the loom and the tension is gone.

Freestyle patterns

Here are some more freestyle patterns, the boxy ones turned out to be more stable than the meanders – it’s really satisfying to see them emerge from the abstract set of rules that you work with to lift the shafts, not unlike graphics programming. Which of the 4 shafts to lift can be thought of like 4 bit opcodes with different ordering resulting in indirect pattern shifts.

There are three types of limitation that I’d like to note and think about (especially in terms of incorporating them in a programming language). One is the selvedge, as I mentioned earlier – another is floats, which cause the problems on the meander pattern (long threads not incorporated into the fabric). The third is more subtle, some sequences of sheds cause problems when packing down the weft, for example if you are not too careful you can cause the ordering of the weft colours to be disrupted in some situations.