Tag Archives: piecing accuracy

Cutting your fabric to achieve accurate ¼ inch seams

One of the common problems all quilters have is achieving an accurate ¼ inch seam allowance. Using the ¼ inch piecing foot or a ¼ inch mark on our sewing machines is not enough. Depending upon the thickness of our fabric and thread, folding the seam over “takes up” a little width. Most of us try to compensate by sewing a “scant” 1/4 inch seam.

Of course it also depends upon how many seams are going to exist in a block. For a simple block like a four patch, there is only one seam in each direction so it doesn’t matter so much if the seam takes up a little extra. But for blocks with many seams, it can be a major problem.

Here’s an alternate approach: cut the strips or pieces in your quilt slightly larger. And I do mean slightly. You can use the lines on your rulers to do this.

Here is an example. I am using an old ruler I own manufactured by Quilter’s Rule. It has rather wide lines. For newer rulers with narrow lines, you will have to develop your own method and run tests to figure out the amount of adjustment needed.

For the purposes of this test, I cut six 1 ½ inch wide strips, each about 6 inches long. First, I cut them aligning the fabric edge with the middle of the 1 ½ inch line, as shown in this photo.  Ignore the fact that the ruler line shown is the 1 inch line; I took the photos after completing the test and placed the wrong line on the fabric edge.  Just pretend it is the 1 1/2 inch line!

Cutting with half of the line thickness

Cutting with half of the line thickness

I then sewed these six strips together using my ¼ inch presser foot and being careful to sew accurate seams. Afterward I pressed the seams carefully, using “Best Press” to get the “block” nice and flat. The resulting block is shown below. The extra fabric taken up in the five seams results in a block that is too small – 6 ¼ inches instead of 6 ½.

Finished test block using half the line thickness is too small

Finished test block using half the line thickness is too small

The second test was done aligning the fabric with the left edge of the line, shown here.

Cutting using all of the line thickness

Cutting using all of the line thickness

Again the six strips were cut and sewn together. Now the block is 6 5/8 inches, slightly oversized. But it can easily be cut down to 6 ½ inches if needed.

Finished test block using all the line thickness produces a big enough block

Finished test block using all the line thickness produces a big enough block

I have also done this test with a newer “thin line” ruler and learned to judge where to line up the fabric edge to make the strips slightly wider.

I really like the idea of solving this size problem in the cutting of the strips, rather than trying to solve it later in the sewing. I am going to try to make it a habit in the future, especially when constructing pieced blocks with many seams. Maybe you will find this a useful tip also.