A long time ago before the trip to Idaho and the basement flood and my computer crash, I promised to write about how I did the gussets for Summer Spice.
The sweater was knit bottom up and in one piece. Other than the three needle bind off shoulder seams, the rest of what looks like seams are fake - a column of two purl stitches into and out of the underarm gusset.
The small underarm gusset allowed me to avoid armhole shaping and get a better fitting drop shoulder sleeve than if the gusset wasn't there.
I wanted a smallish gusset about 1.5 inches/9 stitches wide and about 2 inches/18 rows long. The number of stitches and rows is calculated from the garment gauge.
The bottom half of the gusset/1 inch/9 rows of increase, is knit in the round with the body. The remaining stitches are put on a stitch holder. The top half of the gusset/1 inch/9 rows of decrease, is picked up with the sleeve. The sleeve and gusset are also knit in the round.
The beginning and end purls in this gusset pattern are the two purls of the sweater side seam that already exist.
Row 1: p, M1, p
Row 2: p, k, p
Row 3: p, M1 left, k, M1 right, p
Row 4: p, k3, p
Row 5: p, M1 left, k3, M1 right, p
Row 6: p, k5, p
Row 7: p, M1 left, k5, M1 right, p
Row 8: p, k7, p
Row 9: p, M1 left, k7, M1 right, p
Put seam purls and 9 gusset stitches on hold. Pick up with sleeve.
Row 10: p, k9, p
Row 11: p, ssk, k5, k2tog, p
Row 12: p, k7, p
Row 13: p, ssk, k3, k2tog, p
Row 14: p, k5, p
Row 15: p, ssk, k1, k2tog, p
Row 16: p, k3, p
Row 17: p, slip 2 knitwise-k1-psso, p
Row 18: p, k, p
Row 19: p, p2tog
Resume p2 seam.
As always, for much more detail on gussets including many different kinds to integrate with different types of side seams, this is the book to buy. It's one of my most used knitting reference books, written so even a beginning knitter can learn to knit a bottom up, seamless gansey.