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Monday, 26 November 2012

cleaning


So, the looms at college are not generally as clean as I'd like them to be. This is to be expected as I'm a little bit odd when it comes to looms. My loom at home is tenderly cared for and loved whenever I see it. Which isn't often, sadly. But heyho.

Anyway, I was unhappy using shafts that had all sorts of random, bent, different sized heddles, many on the wrong way round and some crossing each other. So I found a couple of rounds of barely-used heddles in a cupboard and decided to take the old ones off and put the new ones on.

Also, I wanted to clean the loom anyway, as I am unhappy with the idea of weaving on an unclean loom, it seems like it'll make the cloth dirty. And I don't want dirty cloth.

So, for the first time in this establishment I have orderly heddles. And a clean loom.


I don't know if I mentioned that I managed to get texsolv put on all the looms instead of the manky old cotton string, so now we get better shedding. Hurrah! I love TexSolv, trust the Swedes to come up with a brilliant idea like that. Gotta love those Nordics, excellent people.


And that's the warp, ready to go. It has conductive yarn in it. But I'm playing my cards close to my chest as it's a secret project. Not, like, totally secret, but it'd be daft to throw it up on the internet where everyone can see. If I feel it's marketable I'll try to put some kind of open license on it so people can replicate it for personal and educational purposes and give me exclusive license to manufacture for profit. If such a thing is possible, pretty sure it can be done with software, so I don't see why not, in principle.

Saturday, 24 November 2012

Embroidered LED circuit

Whooo! CONDUCTIVE YARN!!

Like, actual yarn, not something with a continuous filament of steel in it, which is basically wire!

Well easy to work with, happy days :)

I wanted to make a square wave generator, but I haven't figured out a good way to sew on the IC's. They're a little fiddly. Also, I can't find my wee baggy of 555's, so I'd have to use half a 556 instead and that seems wasteful.

So, you might not be able to see the traces that well, on the left hand side I measured out a little over 1kohm worth of yarn and darned it back and forth as a resistor. So that's cool.

Everything else is just embroidered in. As you can see it works. So that's a start

 * * * I have a new blog, brew4drunk, detailing my fun and trials learning to brew wine, beer and other forms of alcohol * * *

Sunday, 11 November 2012

Twisted Band

There are two seperate packs of 20 cards here, each working independently and then together.

The left hand pack is threaded in the Z direction, the right hand pack is threaded S. If you weave them together they form a chevron. If you weave them seperately they form two different twisted bands.

So, here I wove them together for a but, then seperated them and wove each pack seperately for 40 picks. I then allowed them to follow their natural twist and added a little extra in, by turning the band over in their desired direction, cards and all by 360 degrees.

Then weave them together again for a bit.

And you get this interesting effect. Which is interesting

Wednesday, 7 November 2012

Smart tex again

I apologise for once again using my blog as a placeholder for my notes and planning stuff.

It's just quicker typing it out here than writing it down on paper, and if i saved it as a normal document I'd just lose it.

Anyway.

For the innovation project I will be working from the work I did in last year's innovation project, where I made potentiometers from knitted conductive fabric. I also made knitted pushbuttons. All of which worked, but the potentiometers were a wee bit sketchy. Though, funnily,  they're the part of the project that was picked up by someone else, and was used as the basis of a synthesizer with a knitted textile interface.

Simply a 1D potentiometer, with a single variable. Pressing it against a conductive surface at various points along it's length caused the resistance value of the circuit created to vary, thus making the circuit do different things. It was all analog, my good man Tom is all about the analog.

This year I want to expand on this, by creating a 2 dimensional resistive touchpad. Regular resistive touchapds work by having two conductive sheets which are pressed together by a finger or a stylus or something. Then the resistance is measured from various places to tell where exactly on the pad the contact is being made. It is an established technology with lots of uses and applications and stuffs. I'm going to try doing it with knitted fabric, because I'm super special and that.

So, this should consist of three things, which need to be explained in more detail

  1. the interface, made out of fabric
  2. an analog electronic part, for basic processing of the signal and that
  3. a computer for to take the input and make it do something on the screen

So, the fabric interface works like this. Simple huh? It works fine for push-to-make buttons


The conductive layers will be made up initially of a regular single jersey fabric knitted from that silk steel yarn I have from last year. The non-conductive part will be made of some kind of slightly open knitted fabric made from some kind of fibre that doesn't give me any greif by felting or absorbing and significant amount of moisture. Like some kind of artificial filament, maybe polyester or nylon or something. I'm sure there's nylon to be had. The point is that it has holes in it so by pushing you can cause the conductive layers to contact each other. Otherwise they are held apart.

I think it would help if the whole thing was held reasonably taught. For two reasons. Firstly it'll be easier to use if it's nice and flat and all rumpled up like last night's knickers. Secondly, the natural resistance of the overall cloth varies when it moves if it's slack. We've found that holding it out as tight as can be causes it to be much more stable, which is to be desired.

The analog processing part I don't know about, I may not actually need anything there at all. Oh, hang on, I'll need a pull down or pull up resistor in there somewhere to prevent floating points from occuring. Nobody wants that. Actually, maybe I won't need them, because it's a potentiometer doodah rather than a push-to-make. Hmm, I need to think about this.

The computer is a Raspberry Pi which I have in my house and will take into college. It will take input from various points along the fabric and use this to attempt to determine the point which is being pressed. In theory, in practice I expect it to vary quite a lot from a single point if I use raw data. I'll probably have to throw some computation at the problem in order to reduce the "noise". Not sure if that's an appropriate use of the term noise (like in a signal). It's like this, if there's an overal resistance of 1000 ohms across the cloth, and I short it halfway, then I should get a resistance of 500ohms, which the script on the Pi will interpret accordingly. However, what I would expect would be for the resistance to vary between 200-800 ohms in this case potentially due to what I know about this stuff. I am being wildly pessimistic here btw, I'd probably expect it to be much better.

Aaaaaaanyway, there's probably algorithms out there I can simply cut and paste to tidy up the signal I'm receiving from the cloth and make it more useable. I could probably just take 100 readings in a fraction of a second and average them out.

Computation is cheap these days.

So, right.

 I need to collect the following, to do the following with

To make the fabric, I need

  1. A cone or two of the conductive stuff
  2. A suitable non conductive yarn
To get the program working I need

  1. A tutorial on using the GPIO pins to read analog values
  2. Instructions, libraries or code for cleaning up scratchy signals
  3. Perhaps a cut and paste program I can just rip that's made for prototyping touchpads. There must be something out there

The yarn is easy, I'm going to try getting the rest today. I will post links to whatever I find in the comments

Friday, 2 November 2012

Making life difficult for myself

 This is becoming a real pain the backside.

These are 3 sample warps with a mix of card and heddle weaving in them.

It works beautifully in theory.

In practice it's really bloody hard work.

The cards are behind the reed.

This is an overslung beater, with box-changing levers above the batten.

I have to lean over to turn the cards. They're maybe a little too closely packed so it's difficult to open the new shed, and I have to put backbone into that as well

Argh. Why do I do this to myself? Anyway, I also have to hold the heddle-woven ends to the side of the cards on the close of each shed so they don't get all finagled up with the cards and cause me problems. On top of that this loom demands I yank the switching lever to turn the barrel. I should probably put weights on the shafts, but it'll take ages and might not even help.

Och, never mind. Anyway, it'll work out in the end. I've also had to abandon one of the warps because it's unweavable (that whole heddle-ends tangling with the cards issue) and I don't think I'll weave the other as due to geometrical reasons I don't think it'll actually weave at all. Well, it will with heavy wefts, but not with normal wefts. I guess I'm not using a lot of normal wefts anyway so it's all academic.

I have used lags as weft in one sample, and I am using heddles as weft in another. in the heddle weft section I am twining all the cards in the S direction, so in theory the whole thing should twist around itself. I wonder if it will, as it has rigid metal in it. Maybe it won't. We'll see. These are supposed to be final samples (god help me) so I don't think it's a great time for experimentation, but I don't really have a lot of choice.

This is all turning out to be a lot more difficult than I though it would be.

I'm going to do a bunch of warps at the weekend too. I will be embiggening everything. This shall be assisted by the new big chunky weaving cards I ordered recently. I'll tell you about them in the next post after I've had a go at using them. They were made especially to my specifications, which is very nice. They're big.