Here we show you an easy, foolproof way to set a true scant seam allowance on your machine. First, you need to know, there are four seam allowance truths that never vary:
1. The stitching line will always take up a thread’s width of each seam line.
2. The fold line will always take up a smidgen of that seam line.
3. Both the thread width and fold smidgen must be allowed for.
4. Every sewing machine, sewing foot and personal style of sewing is different.
Start by cutting three two-and-a-half-inch fabric squares in three different colors and mark a quarter inch seam line down one side of two of the fabric squares.
Set your machine’s stitch width setting to drop the needle directly onto the mark line and sew the three squares together, stitching directly on that line. Press and turn right side up.
Then measure the distance between the two center square seams. It should measure exactly two inches wide between the seams and the entire sewn section should measure six-and-a-half inches wide, edge to edge. The measurement between my first sewn segment is less than the needed two inches.
Next move your needle one thread width to the right, and without adding a mark seam allowance, sew, press and measure three more squares.
My second sewn segment measures exactly two inches wide between the seams. The entire sewn block piece measures exactly six-and-a-half inches wide, edge to edge.
Once you have your exact two-inch measurement, make note of the width setting. This will always be your true scant seam allowance setting for that specific machine regardless of the quilt project.