As promised I would do a small tutorial how to use the sleeve heads.
The sleeve heads are sewn at the armhole after the sleeve is set in. You can see that the left and right side of the sleeve heads are different in length and shape.
If you fold the sleeve head at the shoulder notch (small slit) you will notice that one part is longer and has a more angled shape at the end, the longer length needs to be placed at the back side of the armhole, the shorter part needs to be placed towards the front side of your jacket or coat.
I am making a jacket from a silk tweed which I ordered from Melody (fashionistafabrics) I used a very thin stretch fusible interfacing for the whole jacket and sleeves.
I use 3/8 inch (1 cm) seam allowance at the armhole and sleeve, and have used a fusible bias cut tape to stabilize the armhole.
Pin the sleeve head shoulder notch matching the shoulder seam, with the edges matching from sleeve, armhole and sleeve heads.
You can sew the sleeve heads into the armhole while you are removing the pins or you could baste the sleeve heads in first which I did here for an example. I used orange basting thread and basted over the stitching line from the set in sleeves.
Sewing the sleeve heads in with the sewing machine and sew a hairline away (towards he seam allowance) from the previous stitching (sleeve inset). The sleeve head is placed towards the machine bed so I can see the previous stitching from the set in sleeve. I used a 3 mm stitch length which is just a bit larger than my previous stitching to set in the sleeves
view from the sleeve head the basting thread is still visible.
Remove the basting thread, the seam allowances are heading towards the sleeve.
Done.