Adjusting Sleeve Caps in a Set-in Sweater

Hey there, folks. Are you finishing up any  fall knitting this week? I've been busy knitting this sweater from the Fall issue of Knitscene, and last night I bound off the second sleeve. Now I just need to block it, seam it, and add a collar. Just in time for my trip to Colorado in a couple weeks!

The Fabrication Pullover from Knitscene, Fall 2013

As designed, this pattern has a classic hourglass body with set-in sleeves. I am a bit more pear-shaped myself, so I cast on and worked the hips as for the third size, then decreased to the stitch count for the second size at the high waist and bust. I planned to work the rest of the sweater as for the second size, including the sleeves and upper body. But as I continued working, I realized that the crossback would be a bit wide for my build, especially considering I'd worked the body to have a fairly close fit. Having a wide upper back, juxtaposed with a fitted lower body, would be incongruous.

So I worked more decreases in the armhole shaping. I also worked the armholes just a bit shorter before beginning the shoulder shaping. Now, when you adjust the width of the crossback in a set-in sweater, that change alone does not affect the sleeves, unless the change is really drastic (like changing the cut-in shape of a set-in armhole to an unshaped drop-shoulder armhole). BUT, when you change the depth of the armhole in a set-in, that does require some changes in the sleeve cap shaping. As you can see in the schematic for the Fabrication Pullover above, the cap of a set-in sleeve is a flat-topped bell. The depth of that bell is NOT the same as the depth of the corresponding armhole on the body. Why not?

Excuse my sad illustration, but hopefully it will help with the concepts here. The side of the bell plus HALF THE FLAT TOP must be seamed to the armhole (seam lines noted by dotted lines). The sleeve cap is a big curving edge that has to fit and be seamed into the armhole, which itself is a curving edge. So working them for the same vertical depth does not equal a clean fit. Some more advanced planning is required. 

There is a reliable formula for determining the depth of a set-in sleeve cap, based on a few known entities:

—the width of the sleeve at the bicep

—the desired width of the top flat edge (generally between 3 and 5 inches for women)

—your stitch gauge

—your row gauge

—the depth of the armhole on the body pieces

From these numbers, we do a few calculations, then use the good ol' Pythagorean theorem to determine the depth in inches of the cap. From there, you can determine the number of rows to work in the cap, the number of stitches to be decreased over the course of those rows, and how frequently to work decreases and bind-offs to achieve that shaping. 

I've used this formula in many of my own garments and it's pretty fail-proof. A well-sized sleeve cap makes the final seaming so much easier and cleaner-looking. If you'd like more info on how to adjust your own sleeve caps, check out one of these resources: my book Knitting Plus or the "Beyond the Basics" article in this issue of Interweave Knits.  If you're interested in how and why set-in sleeves are different from raglans, circular yokes, and drop-shoulders, then you should definitely check out the book Knitting Plus—I cover all of these concepts, which hold true for sweaters in any size, not just plus-sized. 

I'll be back with a finished pullover and some photos for you! Til then, happy knitting,

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