Set-in seams: Here's how!

Set-in seams, also known as Y seams, are used to make blocks that can't be assembled with straight, continuous seams. The stunning quilt shown here, Borealis by Marla Yeager, offers plenty of opportunity to practice setting in seams. The complete pattern and instructions for Borealis will be published in the September 2010 issue of American Quilter magazine, including the instructions below. Set-in seams are a skill every quilter should know, for application in classic quilt blocks such as Attic Windows and Feathered Star. (Yes, you can usually alter block patterns to avoid set-in seams, but adding more seam lines can detract from a block's visual appeal and make the sewing and quilting more complicated.)
In Borealis, most of the seams connecting larger triangle patches to pointed units must be set in. To sew these seams, you’ll stitch only on the sewing lines and not into the seam allowances. On the wrong side of the patches, mark dots, 1/4” from the edges, to indicate the beginning and end of each set-in seam (fig. 1). Place 2 patches right sides together. Use pins to line up the dots on the 2 patches. Then sew from dot to dot, backstitching at the beginning and end, and taking care not to stitch into the seam allowance (fig. 2).                

Add the next patch, sewing one seam from dot to dot and backstitching at each end (fig. 3). Pivot the patch, align the remaining edges, and sew the final seam in the same manner (fig. 4).