A bicep adjustment for a raglan 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:
Raglan sleeves differ from set-in sleeves because the sleeve 'cap' is actually part of the neckline. Another characteristic is that the shoulder line is also part of the sleeve, meaning you need to pay close attention to the amount of vertical stretch your pattern calls for.
First, you're going to draw in the seam allowances all around the sleeve. To find the vertical center of the sleeve, fold the sleeve in half, matching the underarms. Draw in the vertical line on that crease. Where the vertical line meets the hem allowance is one of the pivot points.
Draw a second line perpendicular to the vertical line. You'll draw this horizontal line between the underarm seam allowance points. We have two more lines to draw. Find the approximate halfway point of the armscyes. The back armscye is longer than the front, so this really is just a guesstimate. Draw each line from the armscye point seam allowance to the point where the original horizontal/vertical lines intersect.
Time to start cutting! The first cut, you are going to poke the point of the scissors where the vertical line and hem allowance meet. Do NOT cut through the bottom of the sleeve hem. This is a pivot point. Cut upwards to where all the lines meet, and then out to the back armscye, stopping at the seam allowance. Next, cut from the same point confluence, out to the front armscye seam allowance.
Cut from the center point along the horizontal lines out to each armscye. It really doesn't matter what order you cut the horizontal/armscye lines, but do NOT cut the vertical line up to the neckline. That stays static so we don't mess with the necklines. Lastly, cut into the seam/hem allowances to, but not through, each pivot point. That will give us nicely moving hinges.
Now we're ready to make our actual adjustment.
FULL BICEP:
Gently push the hinges at the underarms outwards to separate the bottom two pieces at the center. When you do this, each armscye hinge will slide underneath.
Place a piece of paper behind your pattern piece, and trace around the perimeter of the sleeve. Almost there! The last step is to even out the dip at each armscye and the hem. Gently redraw each armscye curve, and use a straight ruler to redraw the wrist line.
That's it, you're all done!
NARROW BICEP:
Mark on one side of the vertical line how much of an adjustment you want to make. Gently push the hinges at the underarms Inwards to overlap the bottom two pieces at the center so that one side meets the mark. Do the same for the upper two armscye pieces.
Place a piece of paper behind your pattern piece, and trace around the perimeter of the sleeve. Almost there! The last step is to even out the dip at each armscye and the hem. Gently redraw each armscye curve, and use a straight ruler to redraw the wrist line.
That's it, you're all done!
Happy Making!
Rachelle