The seamless set-in sleeves on this cardigan were a worrying prospect when I first picked up the big square of ribbing and decided to complete its transformation to cardigan. I considered other, less numerically taxing, sleeve shapes – but the deep V on the original LBC is one of the reasons I clamoured to test knit it, and a raglan sleeve would detract from the long diagonal swoop of the neck, while a yoked sweater would simply slope right off me with such a stingy allowance of fabric up front. So, set-in sleeves it would be.
In the end, the calculations were not so strenuous. I used Sweater Design In Plain English as a guide to the shaping of the sleeve and the armhole, and – much as one would for a seamless raglan – worked decreases for each section along four shoulder “seams”. Unlike a raglan, the decreases were worked at different rates: the sleeve is shaped to an arm-hugging curve, the armhole to a steep torso-skimming slope. At the top of the sleeve, I cast off stitches as usual on a sleeve cap, and then picked up stitches along the cast-off edge and knitted in the fronts and back as I completed them.
One nice thing about this approach is that it makes it very easy to put the shoulder seam where I like it (just over the shoulder, towards the back) by knitting the fronts along the top of the sleeve. Once fronts and back have been worked to their finished length, all that’s left to do is join the right shoulder seam with a three-needle bind-off, cast off all neck stitches, and use a three-needle bind-off again for the left shoulder. Simple!