Checking My Math

It’s time for me to get started on the cloth for the vest which means sharpening my virtual pencil by getting out the spreadsheet and weaving software to make sure I put on a big enough warp, have enough heddles and that I’ll have a shot at getting sufficient cloth to make the garment.

Rather than using the pattern I drafted, I decided to go with a store-bought version because it has full instructions for doing a fully-lined, turned vest.  I’m pretty confident in my ability to make small changes (shoulder slope, waist location/length, etc.) and, since there aren’t any sleeves, the armholes should be able to stay as drafted.  However, since it’s a commercial pattern, there’s this pesky problem with fabric size and cutting layouts.  That means doing some math.

Step 1:  Open up the pattern and pull out the instructions/cutting diagram.  Here’s page 1 of the pattern.

It’s number 6075 from New Look/Simplicity – and their “Project Runway” series.  Before you start giggling, it’s pretty much the only one I could lay hands on that didn’t look like I’d just washed up on the shores of a Caribbean island.  And, it’s pretty nice.  The instructions are clear and I’ve liked their patterns in the past.  Plus, at $4, the price was right.  :-)

Next up, a close-in of the cutting diagram.  Please take particular note of the two grey pieces on the far left of the upper drawing.

This is where it gets interesting.  The simplest (and safest) estimate is to look at the 44″/45″ wide fabric estimate for my size and double it since I’d be aiming for cloth of ~22″ wide.  The pattern calls for 1 1/2 yards of 45″ wide fabric, without nap – so I should be aiming for three (3) yards of 22″ wide fabric.  Simple, right?  Sure.  Except for those grey pieces.
In the view I want to make (View A, with the collar – because I think the collar looks better), I need to cut two looooooong collar pieces.  Instructions call for them to be cut on the fold, cross-grain, so that they’re effectively a single piece wrapping around.  From the get-go, I can’t do this.  I’m not interested in weaving 45″ wide (finished) fabric as that’d mean double-weave at a minimum plus the loom waste would be silly.  So, that leaves me to cutting and seaming.  In principle, it should be ok, but I don’t know enough about how these things work to know what it’ll do to the way the collar behaves.  The seam would be at the center line of the back neck and that also implies a build-up of layers.  I’m also a tiny bit concerned about making sure that I have a wide enough piece of cloth so that I can cut the four collar pieces, now with seam-allowance at the fold, and join them to make the two large pieces.  I went ahead and measured the pieces for my size and they clock-in at just over 20″, so in theory, they should be fine.  Emphasis on “should”.
Next is the cloth itself.  From my sampling, I get about 15% shrinkage in length and 17% in width.  If I get out the calculator, I need to weave the full-width of the BW, 26″, to get a 22″ (almost!) overall piece.  And, I need 3.5 yards woven to get three yards finished.  The medallion is a 32-end pattern, so I get 29 medallions plus eight ends left over, and I’d thread those for plain weave selvedge – four on each side.  I’m pretty sure I can turn the draft so that I’m weaving with a single shuttle, which will make it go much faster, but that means warp rather than weft floats – and I’m a little concerned about tension issues over more than three yards of weaving.  Intuition says that it should be fine, since they’re evenly distributed.  Regardless, turning the draft makes all kinds of things go more quickly so I should just do it.  Then again, given the turn, I may get a reverse in the shrinkage – more in the length (floats) than in the width, which would help me with the collar pieces but hurt me in fabric length.  If I end up being short, I can always delete the collar.
If you managed to get through all that, congratulations!  In a nutshell, here’s what I’m wondering:
  1. Other than possible difference in shrinkage rate, can you think of a good reason why I shouldn’t turn the draft?  I’m highly motivated to do this.
  2. What, if any, are the ramifications of having a seam in the middle of the collar?  Remember, this is a fully-lined/turned piece, so it’s the build-up of seams that I’m most concerned about.  But what else?
  3. Also, if I turn the draft, my grain goes in the opposite direction.  It also means vertical rather than horizontal squares.  Should I go with that?  Can I ignore grain and turn my fabric?
What else should I be thinking about?  (or should I just get my ass in gear?)
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7 Responses to Checking My Math

  1. Lynn says:

    More comments later, after work: The seam in the middle of the collar is no big deal, usually, but if you’ll also have a seam in the middle of the vest back, you might think about moving the collar seam to the shoulders (so you’d have two collar seams). You could also think about weaving two pieces of fabric, one for the body pieces and one for the collar pieces, if that would help with any of these issues.

    Turning the draft – I don’t see why not, but I would think someone else has turned an Ms and Os draft in the past, if it works, so you might Google/enquire in the weaving forums.

    Grain – will the medallions be different shapes going one way vs. the other? Do you want that or not? Otherwise, I don’t think it will matter with this pattern which way the grain goes.

    Finally, if you have enough yarn (you did check that, right?), just weave extra, at least half a yard, just because. The fabric might shrink more than you expect. You might make a treadling error somewhere and without extra fabric, the error will no doubt be front and center. Etc.

    • blopeep says:

      Tension issues are the least of my worries, honestly. Unless one of you says “NO!”, I’m ok with that. It’s not a long warp, after all.

      Grain was my biggest concern and I don’t remember exactly what Jean had told me about warp vs. weft, but given that it’s all the same yarn, I’m again not terribly fussed.

      And yeah, plenty of yarn. That was confirmation #1 since it would be a limiting factor for anything that I’d do.

  2. Sara says:

    oh dear.

    Well, if you do not laugh so loudly that I actually hear it up here: this is what I do.

    I measure the widest part of the widest pattern piece.

    Then I figure weaving width, after washing and pressing. This is my starting point for figuring width in the reed.

    Then I weave about twice as much as I think I will need (lengthwise) to accommodate all the other pattern pieces needed.

    This gives me extra, in case I want to adjust where the pieces are cut (warp painting can sometimes put an unfortunate spot of color right where you least want it). It also gives me extra, in case I flub the sewing (see me? so confident! in my sewing! skills…not).

    It also gives me extra for hauling around to classes if the garment is off being photographed, or too heavy to bring (think teaching travel to England or Oz), or if, as has happened, the garment got a hole cut into it and had to either have the whole sleeve replaced, or face life everafter with an ugly mend.

    So, in closing, let me say the only important thing for me, is to not have the fabric too narrow. Length, I got covered. There is no “too much fabric”.

    • Lynn says:

      Sara, you are so very sane.

    • blopeep says:

      So. The widest pattern piece, by far, is that blasted collar. That’s driving this whole thing. And, with the 16 yard warp on Gilly, I won’t have that clear any time soon. Now, I could just forget that stupid collar and do it without. That’d make everything simple.

      Oh, and Lynn, if I ignore grain and turn the collar piece, then I could, conceivably, do it as a single piece. I had thought about driving the collar seam to the corners in some way, but maybe I should just forget about it and do one without the collar.

      Added bonus – no collar means that 3 yards would be plenty. PLEN-TY! I think I’ve talked myself into a decision.

    • Lynn says:

      Weave a related fabric for the collar, and I’d say there’s no reason at all why the collar pieces couldn’t go the other way on the grain.

  3. Sara says:

    Yes, I usually turn the collar and cut across the grain. So far, my collars have not suffered unduly.

    They might improve with a neat trick I learned recently: cut the underside slightly (ever so slightly) smaller than the topside. It will make the collar roll slightly when it’s worn.

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