Altering Arms on a Pattern
Large Arm
Cut along the center line and open up the piece the required amount. Add half the amount of the opening to the front and back side seam.
Large Upper Arm
Using a tape measure on its side, measure the length of the top sleeve length. Cut open from center top to bottom and across the sleeve cap. Pull apart opening the center seam. The two sleeve cap pieces will overlap on to the lower sleeve shortening the top sleeve seamline measurement. Re-draw the top sleeve cap measurement with the original measurement.
Narrow Sleeve Cap
Cut down from the center line and across to the side seam. Pivot the piece to create an opening. Re-draw the sleeve head. Add half of the opening width to the shoulder seam.
Small Arm
Measure the sleeve cap measurement. Fold out the required amount along the center line. Re-draw the sleeve cap with the original measurement.