Need to change the position of the vertical cup seam? This tutorial is for you!
If your apex (the fullest part of the breast, usually the nipple) is not aligned with the vertical seam, it may benefit the fit and cup shape to move the seam. In this example, I will be moving the position of the vertical cup seam inwards towards the center. This adjustment may be necessary for large cup/small band sizes.
To begin, measure the distance between your apex and the seamline. For this tutorial I will use 1/2"/6mm.
Gather your Inner Cup and Outer Cup pattern pieces. If you are making a foam cup or lace overlay, those pieces will need to be adjusted as well, after adjusting the main cup pieces. Transfer the notch positions to the cup pieces and remove the seam allowance along the vertical seam.
Draw short guidelines at the top and bottom of the cups to make sure we don't lose any of the vertical length when we re-draw the seam.
On the Outer Cup, add to the cup seam the amount the seam needs to move inwards. In this example I am using 1/2"/6mm. Follow the shape of the original seamline. On the Inner Cup, move the seam inwards 1/2"/6mm. Be sure to keep the same vertical length. This adjustment will also bring the strap position inwards; it is important in a wireless bra to have the straps aligned with the apex for proper support.
Mark the new strap position, copying the shape from the original cup pieces. Blend the new lines into the armhole curve and neckline. Transfer the notches to their new positions. Measure the vertical cup seams on both pieces to make sure they still match and that the notches align.
Add 1/4"/6mm seam allowance to the vertical cup seam. Transfer the notches into the seam allowance. Adjust the foam cup pieces and lace overlays, if necessary. Enjoy!
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