Let's Test the Seam Allowance
- Install a quarter-inch or standard presser foot on your sewing machine. If using a standard presser foot, try to determine which vertical groove on the machine's throat plate is equal to a 1/4" seam allowance.
- Align a a 2" x 4" light strip with a 2" x 4" dark strip, right sides together and edges carefully matched.
- Sew the patches together lengthwise, feeding them through the machine with the 1/4" presser foot's right edge aligned exactly with the right edge of the patches. For a standard foot, align edges with the mark for 1/4".
- Sew another light strip to the opposite edge of the dark strip.
- Press seams allowances toward the dark strip.
- Use a rotary ruler to measure the dark center strip. It should be exactly 1-1/2" wide along its entire length. The outer strips should be exactly 1-3/4" wide along their entire lengths.