A bicep adjustment for a dolman (grown on) sleeve is a bit different than a set-in sleeve. The characteristics of when you might need one are similar. If your bicep is fuller than the pattern is drafted for, the armpit of your garment may be uncomfortably high and/or the fabric is stretched too tightly around your bicep. If your bicep is smaller than the pattern is drafted for, you'll have extra fabric around the sleeve.
Rivet has a bicep measurement on the size chart, and we also give finished bicep measurements in our patterns. We do this to give you solid numbers to base your adjustments off of. If the pattern you are working with does not include these measurements, you'll need to flat measure your sleeve piece to determine your adjustment.
To measure your bicep, make a 'Rosie the Riveter' type move and measure the fullest part of your bicep.
If you would like to follow along with me in a video, check these out:
Dolman sleeves are different from set-in sleeves because the sleeve is 'grown on'. Meaning that the sleeve is actually part of the bodice piece. You may find patterns where the long sleeve is a separate piece, or it's all one piece. The adjustments are pretty much the same. In all cases, your adjustment is going to be at the underarm bicep area.
If you have a two piece bodice/sleeve, it will be at the junction. If it is all one piece, you'll have to estimate the bicep placement. Your pattern piece(s), will look something similar to these.
FULL BICEP:
When you make this adjustment, you do not want to mess with the horizontal line from shoulder to sleeve. Your adjustment will be made at the underarm. Match up the underarm of the bodice and sleeve (if your sleeve is cut on the fold, it will not be quite as tall as the bodice to account for the seam allowance). Take the amount you wish to add and divide it by two (front + back). Measure down by that much, mark, and shift the seam allowances. Draw a gentle line to curve back into the underarm on the bodice and the sleeve.
That's it! That's really all there is to it!
NARROW BICEP:
When you make this adjustment, you do not want to mess with the horizontal line from shoulder to sleeve. Your adjustment will be made at the underarm. Match up the underarm of the bodice and sleeve (if your sleeve is cut on the fold, it will not be quite as tall as the bodice to account for the seam allowance). Take the amount you wish to subtract and divide it by two (front + back). Measure up by that much, mark, and shift the seam allowances. Draw a gentle line to curve back into the underarm on the bodice and the sleeve.
That's it! That's really all there is to it!
Happy Making!
Rachelle