Cut 3 strips 1 1/2" x 4" (approximately), using 2 different fabric colors. Sew 2 of the different fabrics together along the length of the strips. Then sew the remaining strip on the opposite end. Press the seams toward the center.
Now, using a ruler measure the center it should measure 1". If the seam doesn't measure 1" your will need to adjust your needle positions. The picture below shows the seam allowance is just short of the 1" so the needle position will be adjusted slightly.
If you don't find your correct adjustment, Be Patient, just keep adjusting and retesting until you find the correct setting. Once you have the correct adjustment, it will make pay off on your next project.
How do you test your Seam Allowance Accuracy? Comment Below!
Have a Great Sewing Day,