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2015/11/15

Metric Flying Geese

Another blog post purely for the purposes of keeping track of details, in a way that might benefit someone else.

I live in Europe, and I quilt. In practical terms this means that I engage in an imperial hobby in a metric environment. This is not dramatic except when following a pattern for which absolute accuracy is called for, since 1/4" is actually 6.35mm, and who has that marked on their throat plate? Conversely, European seam allowance is 7.5mm, which is just enough wider than 1/4" to lose your points.

I particularly like the "flying geese" block, which, when made using the simple 4-at-once method (video link), demands a rather high degree of cutting accuracy to ensure that everything lines up and nothing overlaps once you're done. If there is any such thing as a "metric precut", 10cm is a common square size, and I happen to have a stack of 10x10cm Christmas precuts which I wanted to put into an "Flying home for Christmas" all-goose hanging. So, doing as every quilter these days does, I asked Pinterest. Only one hit came up. Joy oh joy, it used 10cm squares, and said that the small squares for the fast-four method should be 6.5cm. So I checked back with the seller of the 10cm squares and promptly cleaned her out of the rest of her wares in that line - which just happened to be 6.5cm. I figured this was for a reason, and sewed forth.

(Image source for Fast Four Flying Geese method;  also the website spreading goose untruths)

Peeps, Pinterest lied*. 6.5cm small squares are far too large. They leave so much overlap that two of the four geese blocks had to be ripped apart and resewn to hide the extra flappy bits. This totally defeats the purpose of a "quick and easy" mass-production method.

*shocking, I know

I salvaged my test block and got out a pencil and figured it out for real. And here it is, including process.

This website told me what metric seam allowances (SA) to add to squares destined to be HSTs and QSTs:



HST QST
imperial 7/8" 1.25"
metric 2.5cm 3.5cm


And this blog helpfully posted the algebra for figuring out the cut sizes:


if
x= finished height


y= finished length


z= cut size (small or large)




then
x+(HST SA)=zSmall


y+(QST SA)=zLarge




when
zLarge = 10cm
(our known pre-cut size)

y+3.5=10


y=6.5




thus
x=3.25
(as flying geese are 1:2, height:width)



and so
3.25+2.5=zSmall


5.75=zSmall



Hallelujah, we have a working hypothesis! For Fast 4 Flying Geese in metric using 1 large square @ 10cm, you'll need 4 small squares @ 5.75.

A test block has revealed this to be accurate. But perhaps too accurate; due to the vagaries of bias, I have found that a generous 5.75 or even 6cm retains your points and allows a nice square-up trim.

I have typed this up around the evening chaos and meal, and now I need to hit Publish so I can go read bedtime stories. If I think of it, I'll upload photos for those of us who need to see this stuff before it makes sense.

3 comments:

  1. Hello Lauren, just saw your post about metric flying geese, i know your post is from 7 years ago, but if you see this, let me know. I found in another blog that for the large square we need to add 3.5cm and for the smaller squares we need to add 2.5cm.... this way it gives a generous rectangle geese that we can trim down... Thank you though, i have been trying to find a metric geese chart for some time now....
    Eleni

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  2. Hi Eleni, thanks for the tip! I gave up on metric, donated my cm ruler to someone who will (maybe) use it, and have declared my sewing room to be an Imperial Measurement Zone. Until I want to know how big the quilt will turn out, then I have to convert the final size to metric 🙄

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  3. I have also been trying to do metric flying geese. The only advice I have found is your post and the one that Eleni refers to. I laughed when I read that you have given up on metric. I have decided to go back to knitting. It is easy to knit flying geese. For some reason the stitched version (metrically speaking) has defeated me. Thanks so much for your post; it gave me hope (briefly).

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