I had a few questions about how I adjusted my sleeve head on the Inari dress for the forward shoulder adjustment I did, and I figured it warranted its own blog post. Please keep in mind that this may not be 100% legit - I'm not a professional, and while I've done a fair amount of research on fitting, almost all of that research is geared toward solving my own fitting problems. I've tried a few different things to adjust the sleeve heads after a forward shoulder adjustment, and this one is the one that usually works well for me on my body.
I also want to give credit where credit is due. I first learned of this type of adjustment from Heather B's blog - you can find her tutorial here. This one is pretty much the same, except at the end.
So, let's get started with the sleeve as it is, unaltered and with the seam allowances marked:
The first thing I've done is to draw a line perpendicular to the grain line, about half way between the front/back notches and the tip of the shoulder. The exact position isn't important, so you can just eyeball it.
Next, make a tick mark along that horizontal line, the same distance from the grain line as you adjusted your shoulder seam, toward the front of the sleeve. My forward shoulder adjustment was 1/2", so my mark is 1/2" to the left of the grain line. (note that the front is on the left side on this pattern)
Then extend that mark, perfectly parallel to the grain line, about an inch above and below the horizontal line.
Cut along the horizontal line - I use a straight edge and my rotary cutter for speed.
Slide the upper piece 1/2" (or whatever your forward shoulder measurement is) toward the front of the sleeve. Line up the upper portion of the grain line with the mark you made before.
Align everything neatly, then tape it together along the cut edge.
Now we need to fix the sticky-outy and poky-inny bits. This is where my method begins to differ from Heather's. First, tape or glue some extra paper to the back of the pattern piece at the front and back of the sleeve. Then take your hip/armhole curve ruler and find the section that most closely resembles the curve of your sleeve head at the seam line on the top section of the sleeve cap.
Now shift that curve in a bit, so that it's positioned in the middle of the difference between the seamlines of the top and bottom sections of the sleeve. Make sure the curve blends nicely with the notch and the top of the sleeve cap.
Use this position to draw in your new seam line.
Do the same steps to the other side.
Now add the seam allowances. Because the new seam line is nicely blended at the shoulder and notch, those seam allowances will still be true; you'll gradually be going out onto the extra paper behind. I just use a ruler and make closely-spaced tick marks all the way up the line, then connect them with a solid line.
Now you can cut along this new edge, trimming away the filler paper.
Notice that instead of trimming away the entire front "sticky-outy bit" and adding to the back "pokey-inny bit", you're actually trimming a bit from each, since your new line is in between.
I've given it a lot of thought, and I think that the reason this method gives me a better fit than Heather's original method is that I need some extra room in the shoulder joint. Since Heather's adjustment cuts away all the excess (otherwise known as sticky-outy bit) at the front, I don't get quite as good a fit with it as I do with this variation. I also don't need as much extra at the back of the sleeve as her method adds; this way, I'm only adding half that amount.
So I suggest you give Heather's original adjustment a try if you need to do this adjustment - it's somewhat less work than the way I do it. And then if you feel like you need to refine it a bit more, give this a try. And if you find something else that works for you, please let me know!