QUANTITATIVE STRETCHING by Theodore Gray

Crossposted from Theo’s new stitchblog. We’re rearranging palegraylabs.com and will hopefully have a functioning blog there soon. –Nina

Welcome to my new Stitching Blog. It’s like my regular blog except all about quilting and embroidery. I’ve separated the two, because I get the feeling that people interesting in my science writing and app-making activities may find all the stitching a bit tedious, and vise-versa. Also, I have taken the liberty of using the same list of subscribers to my stitchcam as the list to be notified (via rss feed) when there’s a new post on this blog. I figure if you’re interested enough in stitching to get real-time notifications of a quilting machine running, you’re probably interested enough to hear about an occasional blog post.

So without further ado, my first new stitching-related blog post. I’m afraid it’s a rather technical one….

One of the big problems with fabrics and quilting is that fabric is not a proper engineering material. It’s stretchy and sloppy and never goes exactly where you want it to. The situation only gets worse when you add batting to the equation.

We’ve been experimenting with extra-thick batting, as much as two inches thick, and have had a problem with the resulting “quilts” not lying flat, because some parts of the pattern shrink the dimensions of the fabric more than other parts, resulting in a sheet that is internally stressed.

You might think it’s a simple case of more stitches equals more shrinkage (as it more or less is with embroidery), but this is not the case.

To see why, consider a cross section of a quilt with different spacings between the quilting lines. When there are no lines, the fabric on the top and bottom are flat, and the piece overall will be just as long as the fabric originally was. As you add more lines, the fabric is forced to go up and down, so even if the fabric isn’t physically compressed, the piece overall will get shorter.

Here is a schematic illustrating this fairly obvious fact. Clearly if the lines (the top and bottom fabric) stay the same length, the overall length of the quilt must get shorter.

But what if you keep going? There is a fallacy in this drawing: The thickness of the quilt is staying the same. Clearly the following is NOT what happens if you add even more lines:

These diagrams get more and more absurd, because of course what actually happens is that the batting gets hammered down, the piece gets thinner overall, and the fabric goes back to being flatter. And that means the overall piece should start getting LONGER again, at a certain point. That’s what I wanted to confirm and quantity, so I had Behemoth stitch twelve different test strips like these, each about a meter long:

Here is the diagram again, except this time the widths shown are real, measured widths from my experiment. (In the diagram below, the number of humps is real and the relative lengths are real, but the thicknesses are schematic, because I didn’t measure the actual thicknesses):

As you can see, there is a minimum length around 30 humps, and by the time you get to 200 humps (0.5cm line spacing) the thing is well on its way back to its original length.

Here is a plot of the lengths as a function of line spacing (the right-most data point represents infinite line spacing, in other words the original fabric length):

The interesting fact about this is that, because there’s a minimum, there are going to be two ways to get any given amount of shrinkage, a large-spacing way and a small-spacing way, one on either side of the valley. In order to get a quilt that lays flat, you don’t have to keep all the spacings the same, you can have zones of stitching width spacings on either side of the minimum.

These tests were all with lines in only one direction, but what if you add crossed lines in the other direction? I did a second set of twelve test strips with lines going in both directions, like these:

The following graph is a bit harder to read. The horizontal axis represents the line spacing in the direction of shrinkage (just like in the graph above). The vertical scale is again overall length of the piece. The lines connecting data points represent sets of similar spacing in the lines going the other direction. The bottom set has no cross-lines (i.e. it’s the same data points as the graph above, except a smaller number of them shown). As you go up, each line represents more and more closely spaced cross-lines. The data points are labeled with the line spacing in the shrinkage and crossed directions respectively.

The result is as expected: The more closely spaced the crossed lines are, the less shrinkage there is, regardless of how closely spaced the lines are in the shrinkage direction.

Now all we need to do is actually use this information to make something pretty that doesn’t warp…. In the mean time, we’ve been experimenting with the other solution: Stretching on a frame.

This quilt is “double-quilted”, using the term Nina invented for a thing I decided to try because why not. It’s basically a quilt on top of a quilt, so we can have a secondary level of relief that isn’t hammer down overall. I’ll write a full blog post about this technique later, but here’s a closeup that gives an idea of what it looks like:

Was all the quantitative measuring useful? Maybe…. So far I’ve used it only to create an interpolating function that I have used in some calculations involving how wide to make flaps that wrap around the wooden frame holding up stretched quilts like this. Hm, that’s probably another blog post too.

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God Calls Moses to Mt. Horeb

DONATE HERE: http://questioncopyright.org/sedermasochism

“3 Now Moses kept the flock of Jethro his father in law, the priest of Midian: and he led the flock to the backside of the desert, and came to the mountain of God, even to Horeb.
“2 And the angel of the Lord appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, and the bush was not consumed.
“3 And Moses said, I will now turn aside, and see this great sight, why the bush is not burnt.
“4 And when the Lord saw that he turned aside to see, God called unto him out of the midst of the bush, and said, Moses, Moses. And he said, Here am I.”
–Exodus 3 King James Version (KJV)

Written Designed Directed Animated Produced etc. by Nina Paley. ninapaley.com
Music: excerpted from “Moses Supposes” (music by Roger Edens, lyrics by Comden and Green, vocals by Gene Kelly and Donald O’Connor) from the motion picture Singin’ In The Rain.
Many sound effects from the wonderful freesound.org:
wind: freesound.org/people/medialint/sounds/11863/
fire: freesound.org/people/kingsrow/sounds/181562/
stick: freesound.org/people/davilca/sounds/159494/
thumps: freesound.org/people/FlatHill/sounds/211450/

Director’s note:
Obviously I took a few liberties here.
This is a work-in-progress and may be modified for the final film, Seder-Masochism. Stay tuned for the immediate next scene, where the burning bush gives instructions to Moses!

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Dvorak Diary #3: Introvert

On a recent trip to Trivandrum, India, I decided to try learning to touch-type in Dvorak (after decades of hunt-and-peck in QWERTY). Here I share some excerpts of my “Dvorak Diary”.

Biogradska_suma

Thursday, January first, Two thousand fifteen

Yesterday I awoke with a clear and simple melody running through my head, a really good and catchy one. Then I had breakfast with ____ and it was gone. This is why I am an introvert: I want to hear the music in my head. It’s like a wilderness preserve: clumsy tourists wander off-trail and step on the delicate wildlife, killing it inadvertently. They don’t mean to but the endangered plants and animals don’t care; they don’t survive on good intentions. I miss my melody. It lived so easily in my head yesterday but couldn’t survive another person. Habitat loss. Like the Sitka Deer, much of the life in my head needs a wide range. I am an increasingly grumpy forest ranger, responsible both for the needs of the tourists and the wildlife. The former endanger the latter so I want them to just fuck off. But I need tourists for some reason, like were it not for tourists the forest would be razed for a housing development or mine or parking lot.

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Dvorak Diary #2: Offline

On a recent trip to Trivandrum, India, I decided to try learning to touch-type in Dvorak (after decades of hunt-and-peck in QWERTY). Here I share some excerpts of my “Dvorak Diary”.

japan-earthquake-tsunami-nuclear-unforgettable-pictures-wave_33291_600x450

Tuesday, December Thirtieth, Two thousand fourteen….

I have been kinda ‘offline’ since returning. The last legs of my flights were awful, and I still haven’t recovered, though at this point it’s probably jetlag more than exhaustion that has me failing to connect to ‘my’ world and identity. I haven’t felt connected online, and am concerned about how I let Facebook information just wash over me with no real engagement on my part. It’s a hell of a lot of information to just suck through me like a stream. I surely have more than enough information rattling around in my head already. Maybe it’s time to let it settle, to digest it and let it adjust to the habitat of my mind and maybe make something of itself instead of just washing through like a tsunami. I feel less satisfied being an information node than a full human animal. Jetlag reminds me I am an animal, and no amount of information can heal my exhausted body. I recently read that staring into screens is terrible for sleep – I read that staring into a screen, ha ha – so last night I didn’t check email or read Facebook.

Is Facebook the television of today? It’s not broadcast, and it can be useful sometimes, but I become very passive with it, especially at night when I turn to it in my insomnia.

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