#4 illustration of a finished cornerstone!

When the three sections are sewn together, it should leave you with a 3 1/2" square cornerstone to be sewn onto the sashing at every intersection. Please notice that every intersection meets perfectly due to the use of the diagonal pinning as shown in #3.

#3 illustrates how to pin sections together

Pinning the cornerstone sections together is very important. "But" the seam allowances together and insert a pin beside the seamline on both sides, but TURN THE PIN INTO A DIAGONAL position as shown in the illustration. For some strange reason, doing this makes the seams stay together perfectly! This is a great trick to learn when machine piecing at intersections. The seams will match up every time! AMAZING!
Illustration #3

#2 step is to switch colors and sew strips for cornerstones

#2 step puts the light fabric on the outside edges of the strips. This will become the center section of the cornerstones.

Steps for Making Sashing and Cornerstones

Once you have cut 1 1/2" strips of dark fabric and light fabric for your sashing, proceed to sew them together in the method illustrated below in #1 illustration.