I’m going to show you how to insert a sleeve into an armhole using a classic method which adds fullness at the shoulder.
The reason we’re adding fullness at the shoulder is to help the fabric fold over the curve of your shoulder where it sticks out from your body. A sleeve head is often at least 2cm / ¾” bigger than the armhole (even bigger on the Mathilde Blouse to produce visible gathering as a design detail). This excess fabric is gathered so the circumference of the sleeve head and armhole match when sewn together, forming a slight puff in the fabric to accommodate your shoulder.
(In case you’re interested, not all sleeves are inserted this way. Some sleeve heads don’t have any ease at all. And an alternative method - often used in shirt manufacturing, I do believe - is to insert sleeves “on the flat”, ie. stitched flat against the armhole before the bodice side seam and sleeve underarm sleeve are joined.)
Anyway, that’s the theory over – let’s get on with the sewing!
1) Let’s add the gathering stitches to the shoulders while the sleeve pieces are still flat – it’s so much easier that way. Thread up your machine in a contrasting colour so it’ll be easy to identify and rip out the gather stitching later (it’s only temporary). Set the stitch length to 4mm.
If you’re making the Mathilde Blouse, it also has gathering where the sleeves meet the cuffs, so stitch three rows of gather stitches at the sleeve hem too, beginning and ending about 2.5cm / 1” from each side seam.
2) Stitch the sleeve underarm seams, finish and press. You can use French seams here if you like.
3) Now we’re going to align the sleeve and armhole. The way to check you’re putting the correct sleeve into its corresponding armhole is to look at the little notches you cut from your pattern (if you don’t know what I’m talking about, check the pattern again). The front of the sleeve and armhole will have single notches; the back will have double notches.
Align the sleeve and armhole, with the fabric right sides together. This can be a little confusing the first time you do it. Okay, so I admit it still makes my brain hurt sometimes and I’ve been doing it for years! But really all you need to do is hold the sleeve right sides out and turn the garment wrong side out on top of it so the right sides are matching. Then line up the two raw edges of the sleeve and armhole seams.
Pin the sleeve and armhole together. This bit is a careful operation. Stick the pins in perpendicular to the edge on the sleeve side (that way the sleeve gathers will be facing up when you sew them to help you control them). Rather than sticking the pins in willy-nilly, it’s a good idea to pin at the following strategic points, matching up sleeve and bodice:
- Underarm seam and bodice side seam
- Sleeve and armhole notches (those single and double snips we were talking about earlier)
- Just past the start and end points of the gather stitches
- Shoulder seam and central point on sleeve
- Any other seams that might accidentally fold the wrong way (eg. yoke seam on the Mathilde Blouse).
Don't pin on top of the gather stitches just yet (that bit comes in a moment).
5) If you’re super confident you can go right ahead and stitch. It’s a reeeeally good idea to baste first though to check you’re happy with your gathering. Basting basically means sewing a practice run with long stitches (4mm) which are easy to rip out if you want to try again. Thread up your machine in a contrast colour so you can see your basting stitching easily and thus whip them out quickly. Baste stitch within the seam allowance so your real stitches don’t go directly on top.
When stitching, start at the underarm seam. Sew nice and slowly over the gathers so you can keep them evenly in place as you go. Come full circle to meet your starting point, making a couple of overlapping stitches to secure. Sleeves aren’t the easiest thing in the world to sew, but with a little practice you’ll get the hang of it, I promise.
6) Once you’re happy with your basting (you did baste, didn’t you?), rethread your machine in matching thread to your fabric, reset the stitch length to normal (2 - 2.5mm) and sew your real stitches. Now you can rip out your basting and gathering stitches.
7) All that’s left to do now is finish your seam and press it. When pressing the armhole, turn the garment inside out and press along the seam. If you want to you can press the seam in towards the sleeve, but try not to press the shoulder area, otherwise you’ll lose the fullness you’ve created with your gathers.
Admire your hard work. Hooray! You set in a sleeve!
Like this? See also How to Pleat a Sleeve Cap