Oh, the terrible raglan sleeve! I lived through the 80’s. I still have nightmares about these things (bolstered out by shoulder pads, of course).
On the other hand, it’s an interesting pattern. The deal with the raglan sleeve is that it absorbs the shoulder part of the bodice. In order to make this happen, the bodice has to be adjusted. This process makes it impossible for the normal ease to be added into the sleeve head. Since ease exists to allow freedom of movement, the armscye of a raglan is adjusted to add for movement at the bottom, rather than the top.
Let’s start with the back block:
If you’ve been paying attention to all these demos, you might be thinking, “Gosh, missa, those corners are pretty far from square at the side seam!” If you’re thinking this, I’m very proud. :) There’s a reason I’m not too worried about it this once. The raglan sleeve isn’t set in like a typical sleeve. Instead of making up the body, making up the sleeve, easing down the sleeve-head, then setting the sleeve, it’s far more common to attach the sleeve halves to the body halves, then sew the completed halves together at the shoulder/outer arm and side seams. So that angle is still conceptually annoying, but also really common.
To finish up the front and back bodice adjustments, we need to sort out which part of the shoulder will become part of the sleeve.
We’re doing this because slight curves often look straighter on the human body than straight lines do, and also because that nice smooth curve from the neck into the armscye will be much easier to sew up.
Do the same thing in the back. Make sure there are no angles or really sharp curves where the armscye and cutting line meet.
Now we can prepare the sleeves.
This is where you need the front and back half-armscye measurements that you wrote down. On the sleeve halves, measure the half-measurement for each side, starting from the side seam. (That’s really important!) Mark a guide. I labeled mine X so that it’s different from all the other guides we have going on.
If you transferred a dart on your back shoulder, you should have a piece that looks like a weird happy-cartoon-dog like this. Otherwise, both your pieces will be kind of like this but without the “eye” – just the “grin”.
Do the same with the other half of the sleeve. Do not forget notches.
Your finished pattern pieces should look something like these: