I had a great time this week speaking at the Around the Bay Knitters' Guild, in Dundas, Ontario. We had a fun discussion on Sizing and Fit.
The most interesting part of the evening, however, was a handout offered to the rest of the membership by the lovely and clever Anne, a long-standing member of the group.
The handout is the Machine Knitter's "Chart for Multiple Increases and Decreases". It's a very clever sheet that provides a mostly math-free way of figuring out how to evenly distribute decreases across a row. It's not quite as simple for increases, but for decreases it's handy and rather amusing.
Click on the image to see a larger version.
It's all based on the ratio of target sts to original sts: divide the smaller number by the bigger number. That is, if you have 100 sts and you need to decrease to 50, the ratio is 50/100, which is .5 (or 1/2 if you like thinking in fractions). If you look up .5 in the table, you'll see that it lists a little two-legged stool symbol. That's a machine knitting symbol for a single decrease. For handknitters, read that as k2tog.
So to take any group of 100 sts and reduce it to 50, just repeat k2tog across the row. Simple! And this works for any set of sts you want to decrease that ratio - cutting the number of sts in half.
And if you have 100 sts and need 90, 90/100 = .9. And so looking at the table entry for .9, you see k2tog, and 8 vertical line symbols - read those as just k1. And indeed, if you repeat (k2tog, k8) across, 100 sts will be reduced to 90.
Clever, eh? The only math is a quick division, easy on a calculator or phone (or a reduction to a fraction if you're numerically inclined). And then just look up the resulting number and read the line.
The three-legged stool symbol is a double decrease, e.g. s2kpo. If you have 60 sts and want to reduce it to 20, the fraction is 2/6 = 1/3 = .33, and therefore the instruction is double decrease. And if you have a group of 60 sts and work double decreases all the way across, you'll get 20 sts. And it applies if you've got 30 sts and want to reduce to 10, or 120 sts and want to reduce to 40 - as the result of the division is always the same.
The original sheet credits Kit Way Nee of the Ottawa Machine Knitters Club, and apparently it was printed in Carriage Trade, a machine knitter's magazine published in the 1980s and 1990s. Thanks much to Anne and her friends at the Guild for sharing it with me!