To begin the process of inserting your sleeves we first need to assemble the sleeves. Start by sewing the underarm seam of each sleeve, finish the seam as desired (I serged mine) and press them towards the back of the garment.
Next you’re going to place two lines of basting stitches to help gather any excess fabric into the armhole starting at one set of lower notches, stitching up through the top notch, and back down to the other lower notch. You’ll want the basting stitches to fall at approximately 3/8″ and 5/8″ from the raw edge of the sleeve cap so that you are sewing between them when you set your sleeve.
Pin the sleeve to the armhole with the right side of the sleeve touching the right side of the armhole. You’re going to fist pin the underarm of the sleeve to the side seam of the blazer, then work around matching the front and back notches as well as the top notch of the sleeve to the shoulder seam of the blazer. Once you have those main points pinned, begin working around the gathered cap of the sleeve pulling on the basting threads you placed in the last step to help ease in the sleeve cap. Once you have the sleeve cap in place you’re going to stitch around the armhole.
You can see you’ll have some visible basting threads once you’ve set your sleeve, you’ll need to pull those out. I also remove the line of basting that falls to the inside of the sleeve.
You can then finish your sleeve seam allowance as desired. Like almost all my seams, I serge these together.
Typically I don’t press my sleeve caps as I find it flattens them out a lot of the time, but you can give yours a light steam if you’d like. I like the seam allowance to fall to the sleeve rather than the blazer. Repeat these steps for the other sleeve.
Next we’ll be assembling and attaching the facing for the body of the blazer. Stay tuned!