The Design Process – Yet More Math

Posted on | March 15, 2007 | 4 Comments

After working the bust increases, it’s now time to shape the underarm seam for the doleman-like sleeve.

Instead of using a set formula for the increases, I drew out a chart to make sure the shape is what I wanted. I wanted the increases to be worked over 2″, which according to my row gauge is 16 rows total.

So I got out the trusty graph paper and started drawing. Here’s what I came up with:

So I’m increasing a total of 11 stitches over 15 rows (1 stitch every other row 4 times, then 1 stitch every row 7 times) – close enough to my 16 total.

After working my underarm increases, I now need to figure out how many stitches to cast on for the sleeve at both ends of the back.

I want the sleeves to be about 10 1/4″ long from the shoulder to the cuff. So 10.25 x 2 (sleeves) =20.5″ + 9″ (neck) = 29.5″ wide. Then I subtract the body 29.5″ – 18″ = 11.5″ for the underarm seams. But I have 2 underarm seams, so I need to divide by 2 = 5.75″ for each side or 31 stitches wide (5.75 x 5.5=31).

I already increased 11 stitches for the underarm shaping, so I can subtract that from the 31, so we have 20 stitches to increase.

But before I cast 20 more stitches on for the sleeve, I need to make sure the total number of stitches follows our stitch repeat numbers (7 sts + 4). 99 sts + 22 sts + 40 sts = 161 sts total. 161-4=157, 157/7= 22.428…… = not going to work! So I messed around a bit with the numbers and figured out I needed to add 15 sts on each side (99 + 22 + 30=151 sts. 151 -4=147, 147/7=21 repeats). The sleeve will be about 1″ shorter on each side, but having the numbers work out makes it easier to place the repeats correctly so I can live with that.

After casting on the extra stitches, I was able to veg out for awhile and knit even for 7 1/2″. Once I hit that point, it was time to think about the shoulder shaping.

I decided I wanted to try some short row shaping on the shoulders since I’ve never done it in a design before. Well, I wanted to do short row shaping, but with the lace pattern going on, I ended up with a lot more stitches than I was supposed to, so out it came! I did a traditional bind off instead and slipped the first stitch of each bind off row to avoid the ugly “stair step” edge you get if you don’t do this. To figure out how many stitches I needed to decrease, I subtracted the neck opening stitches from the sleeve stitches and have 51 stitches to decrease on each shoulder over 14 rows. Because I can only decrease one side per row, I actually only have 7 rows to decrease over. So 51/7= 7 with a remainder of 2. So I’ll be binding off 7 stitches 7 times and then have 2 sts at the end left over.

There will also be a bit of back neck shaping involved which will involve separating the back at a certain point, but I think it’s safe to say that I’m pretty sure you just want to see a progress picture by now:

Next up: Math for a cardigan front and neck decreases – fun!

Thanks to everyone who made a suggestion in my time of crisis! I decided on the Rowan DK Wool from for the baby goods. I love Rowan and hey, it was cheap! If it wasn’t a budget project, I probably would have gone for the Zara, but I’m sure there will be a next time!

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  • Connie

    Yay! Another installment in your design series. I haven’t read the second to last installment yet; so I’m going to curl up on the couch and catch up! :) Glad your wool crisis was solved. Sounds like you’ve made a good choice.

  • Kelly

    Wow, this is so much more complicated than I imagined. It’s hard enough coming up with numbers for one size, let alone all of them!

    Glad you found a good wool for your project – sorry I couldn’t help, I had no ideas for you.

  • frecklegirl jess

    Wow. This made my head explode a little bit. ;)

    It’s coming along- yay!

  • schrodinger

    It’s looking great. Although, to be honest, my eyes glazed over a little on the maths – I’m impressed.