Sunday, February 8, 2009

Mathematical! Algebraic! Rhombus!

I read Laura Fry's blog religiously - because I love knowing what others are up to, because Laura's really good to update frequently and I love that in a blog, and because Laura's truly (and literally) a master weaver and her advice and thoughts on weaving and weaving professionally are always worth my time. Besides, how could I not love a woman whose stash is even bigger than mine? "Look!" I can say to Ron. "Look at her stash! Stashes like mine are absolutely critical to being a professional weaver!" (I do not show him the posts she writes about actually using up her stash, of course.)

If you are a weaver, please go spend some time Right Now reading some of Laura's past posts. In particular, read this one, which is what I'm thinking about myself these days. It is about weaving ergonomically, i.e. in a way that is fast and efficient and yet also easy on your body - a subject near and dear to Laura's heart and mine. Your body, after all, is your most important weaving tool - all the looms in the world will do you no good if your body hurts too much to use them. Here's an excerpt (minus the photo which for some reason I am not able to include, so go look at her blog 'cause it's important):

"This is a photo showing how I catch the shuttle as it exits the shed. The point slips through my index and middle finger, and my thumb acts as a gentle brake on the bobbin so that it doesn't over run and let off more weft than required. I catch and throw my shuttle this way regardless of the width of the warp I'm weaving. I know it's hard to relearn muscle memory if you have been doing something physical another way, but working ergonomically is much kinder to the body than working awkwardly."

I read this post when it first went up, and thought "why would catching the shuttle between your fingers be better than catching it as I do now (fingers below, thumb above)??" However, I have learned not to ignore the Wisdom Of Laura(tm), so I've been trying this on my scarvesaday, like the one in the picture up there. You know what? I like it! It's a bit awkward since I'm using heavy 15" Bluster Bay shuttles rather than a small LeClerc boat shuttle like the one in her picture but I've got big hands so it's not too bad.

The primary difference between the two is the angle at which I wind up pulling the shuttle away from the shed. Catching it between my fingers encourages me to draw it straight out to the side rather than curving it back towards my body, so that the angle the weft makes in the shed is less acute. I think I wind up moving my wrist more this way because the shuttle's path is straighter and therefore my wrist must bend to accommodate it, so I'm a little anxious it will aggravate my CTS. I'll have to keep an eye on that.

Really paying attention to the way I caught the shuttle and the angle that created with the weft made me also think carefully about something else that's been dancing around in the back of my mind for a while but hasn't come forward to really be inspected until now. I've long suspected that part of the difference between my left and right selvages has to do with the construction of the end feed shuttles I use and, now that I've really thought about it, it makes perfect sense. In fact, it's basic geometry. It is, as they say, Mathematical!1

The shuttle is 15" long and the weft comes out of a hole about 2" from the left end. That means that, assuming the shuttle is the same distance from the web on either side when I beat, the thread is following a path that's 13" longer when it's on the left side compared to when it's on the right side (because the length of the shuttle is added on the left). I could go into a long discussion of hypotenuses and similar triangles and angles and all that, but this picture shows it all Pretty Clearly, I think:

In both of these pics, the shuttle is about 2" from the selvage. As you can see, though, the thread has to go much farther in the left picture than in the right one, which creates a huge difference in angle. It doesn't look so very different at the selvage where the angle is created, I'll grant you, but look at the opposite selvage. The height of the right triangle is almost twice the left, which means there's a big difference in that angle whether you can see it or not - which means that there's more thread in the right shed than in the left one because that hypotenuse is longer, which means I'll get less draw-in there. Really, the angle at the selvage is all about leaving more or less thread in the shed anyway (i.e. adjusting the length of the hypotenuse).

So, what does this mean for me? It means that, assuming I catch the shuttle the same way on both sides and pull it out the same distance on both sides and move my body the same way on both sides, when I'm using an end feed shuttle I cannot expect my selvages to look alike. And, since I do want my selvages to look alike, I need to do something different on one side. And, because I like to move my body in essentially the same way all the time (the unconscious movement is part of the zen of weaving for me), I don't want to do things dramatically differently on the two sides. I could train myself to catch the shuttle closer to the beater on one side than the other but, as you can see, I haven't got much space to work with on Joey - he's got a very shallow little weaving area.

Enter Laura's way of catching the shuttle, which naturally causes me to pull the shuttle towards my body less and therefore create a wider angle vs. my way of catching the shuttle, which naturally causes me to pull the shuttle towards my body more and thereofre create a shallower angle. In this case, I'm using "naturally" to mean "unconsciously", i.e. it happens naturally without me having to think about it - good for Weaving Zen. I spent my last warp trying to practice catching the shuttle her way on the left and my way on the right in order to even out the angles and I think it worked pretty well. I'll keep practicing it and see how it goes.

A few additional thoughts:

1) I've noticed that catching the shuttle my way eventually tires out my left pinky and ring finger. Doesn't happen on the right hand, for some reason I've yet to determine, but it does on the left. Catching the shuttle's Laura's way doesn't seem to do this since, of course, I'm not bearing the weight of the shuttle on those two fingers but rather on my middle finger. So, using her method on the left side relieves that discomfort, which is a great bonus. It remains to be seen whether my middle finger will get tired the way the other two did.

2) This difference in angle and weft-left-in-shed is pretty severe on a narrow warp like the one I've currently got on Joey but would be almost non-existent in a wide warp like the blankets I plan to put on Mabel next. I'll have to try catching the shuttle Laura's way on both sides of that warp. She says she does this no matter how wide the warp but I suspect it's going to be difficult for me to catch a BB shuttle her way on a 50" wide warp when I'm already having to rock pretty far from side to side just to catch the shuttle at all. I'll definitely try it, though. Doubt Ye Not the Wisdom of Laura!

And now I'm off to prep for my Unspun Heroes fiber fiesta! Have a lovely Sunday, one and all. :)

1. This and the title of my post is a reference to a Youtube video, and the "they" in question are friends of mine that occasionally stop by HFD for a visit. You Know Who You Are. The rest of you may or may not enjoy the video, which is Very Very Odd Indeed, but I wouldn't recommend reading the comments.

My apologies to anyone who actually expected algebra and rhomb...rhombuses? rhombii? in this post. You'll have to settle for geometry and triangles instead.


Sue said...

Love the picture of that latest scarf!! It's gorgeous!

So, if I'm understanding correctly, the thread doesn't come out the center of the end of the end-feed shuttle? Or you don't flip the shuttle around when you weave with it?

I'm thinking a lot about draw-in and selvedges myself these this is interesting to me.

One more question....if that's OK.

If you need the weft to be angled to minimize draw in on a narrow warp, when you weave a wide warp, is there enough space for the angle, or is there some other technique? (If you want me to go research this myself, I understand....but it seems like something you might know the answer to!)


Janet said...

Thank you for the lovely scarfy compliment! :D That was my fave of all the warp #1 scarves - too bad it's also the short half-a-scarf. Will just have to repeat it later! It's also given me some ideas for tea towels...

Your questions are more than okay, they are fantabulous. Only catch is that I wrote so much to answer them that I wound up putting it in a whole new post, and I didn't even get to address your question about wide warps very directly yet! There's more to say about that but I haven't got the time right now, so Watch This Space.

Laura said...

Hi Janet,

The weight of the shuttle is very important to reducing stress on the hands and wrist.

I wove a warp using a borrowed AVL end feed shuttle and had loads and loads of pain, just because of the weight of the shuttle compared to the Leclerc boat shuttles.

I'm not a fan of end feed shuttles, partly for that reason. I suggest you amp up the tension on the feed slightly. That should help to seat the weft loop at the selvedge better. It's probably just a smidge too loose.

Discovered this during the yards of 60" wide fabric I used to weave using fly shuttles. The amount of tension on the weft thread is actually more important than the actual angle *in* the shed.

Since you have a shuttle race, you might like to study Allan Fannin's technique of shuttle throwing where he doesn't actually lift the shuttle off the race, but leaves the end point resting there while beating. That way you aren't actually lifting the weight of the shuttle entirely. This method works very well with a hand end-feed shuttle.



Peg in South Carolina said...

Thank you for posting the two pictues with the angled wefts. They blew my mind, as they say!