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Thursday, 14 March 2013

A twisted yarn


Did I mention I was making yarn? Probably, I know I've been wittering on about the twisting machine and the twist measuring machine lately. Well, here are my first proper results.

The one on the right is called Stretch Starlight and is made with 97/3 merino/lycra with small pieces of English 56 thrown in and the one on the right is called Nebula, which has a greater amount of a longer staple woollen fibre of unknown origin attached to a regular worsted yarn.

These yarns are not yet perfect, but I think I'm getting closer. I still have problems with the fibres not binding into the twist perfectly. Of course, the Boyd isn't actually designed in any way to bind fibre into a twist, but it's a wee hack I guess.



How are these made?

Well, these are what's called Siro yarns. What this means is they're folded yarns made of singles which are practically unspun. In effect this means that when you remove the folded twist what you're left with is roving. As a consequence you can't remove all the twist, as the stuff simpy falls apart.

But I have to untwist this stuff and retwist it in order to get the extra fibres to bind to the yarn.

So first you go and measure the twist of the yarn, as I explained previously in a previous post previously.

This yarn has 13 twists per inch in the S direction, or 13 TPI S, as it shall henceforth be referred to as. henceforthly.

A brief aside regarding yarn twist.

S or Z twist refers to the direction the yarn is twisted in. If the yarn is twisted in a counter clockwise direction you get an S twist, if clockwise, you get a Z twist.

Look at the yarn closely, then imagine the letter S or Z superimposed upon the twist direction, and whichever of those diagonals it follows indicates which twist it is. Quite simply really, though one does wonder how folks with different alphabets, such as Arabic or Chinese speakers go about describing this. I must ask.


Anyway, moving onward (ever onwards), as the yarn had 13 TPI S I had to twist it in the opposite direction in order to remove some ov the twist, but not so much that it became too fragile to run through the machine. So I twisted it 5 TPI Z, another way of saying this is that I removed 5 TPI S

13 TPI S + 5 TPI Z = 8 TPI S

Simples, as the insurance rodent would say.

Anyway, then I have to twist it back.

You'd think I'd simply twist it back 5 TPI while adding the fibre. Oh, if only life were so simple. You see, the stuff doesn't really bind that well on just one twist, so I feel it's better to add it and then retwist to give it a better shot at really binding into the yarn.

So you'd think I'd do 2.5 TPI S twice, to get it back to where it was, right?

13 TPI S + 5 TPI Z + 5 TPI S = 13 TPI S

Of course, you've guessed it, things aren't that simple.

You see, the twister twists onto these big old wooden packages, which are fine for nice big heavy yarns which have actual twist in their singles, but this yarn is none of those things. It is light, fine and has no twist in it's singles. So it needs to be on a nice light package that rotates easily on the upper yarn holders.

Here's where things get weird and a little maddening.

So, I take this big wooden yarn package over to another machine, a cone winder, and transfer it onto a small plastic sample cone. The only problem here is that as the yarn is coming off the bottom package into the tension guide of the machine, it is twisting. Not a lot, but enough to make some kind of a difference. And I don't do that once, or twice, but four times in the process of making this yarn. Here's how it goes.

Yarn goes like this

From big 2 kilo cone to small package

From small package, twisted onto large wooden bobbin + 5 TPI Z

Bobbin to package

Package to bobbin + 2 TPI S

Bobbin to package

Package to bobbin + 2 TPI S

Bobbin to final package

Everytime I transfer from bobbin to package I add an unknown amount of twist into it, in which direction I am unsure, as I haven't taken the time to examine the process in such minute detail yet.

Also, I am reliably informed by a PhD student that the twist added in this manner is very difficult to ascertain as it is determined by the size of the package, the circumference of the yarn on the package at any given point (which is always shrinking), the distance from the yarn to the tension guide (which changes as you go along as the yarn runs up and down the cone on it's way round), the tension of the tensioner and even the speed of the machine.

All you can say is you have to work it in somehow.

The upshot is that it's next to impossible to create a philosophically perfect yarn using this technology. Luckily you can simply steam the stuff, but in practice you have to make allowances.

So I spun 2 TPI S twice and got a yarn that is close enough to being perfectly balance that frankly I'm happy enough with it.

Now I just have to hope the coloured fibre parts will make it all the way through the loom and into the cloth.

Wish me luck

2 comments:

blanketweave said...

Hi Andrew
I found you by looking for info on old yarn twisting measurement machines, and you're doing something really interesting. Thanks for the video.
peggy

blanketweave said...

Found you via a search for yarn twist measuring machines. You're doing some creative stuff!