How to stitch a Quarter Inch Seam

In patchwork and quilting it is important to be accurate with cutting the fabric. What is often forgotten is that the stitching of seams should be accurate as well. On some designs if you get your seam allowances slightly wrong it does not matter too much as it will just make the whole project slightly larger or smaller. However on other designs it can turn the construction of a quilt into a nightmare if the pieces do not really fit together because the sizing is slightly out.

The trouble starts when there is one square to be joined to another square with the latter being made up of several pieces. If the seam allowances on the pieced square are too big then the whole square will become too small to fit the side of the square made of one piece of fabric. So - don't let dodgy seam widths spoil your sewing. Why not try to get it sorted and make stitching your quilts a breeze.

Quarter Inch Seam

The above shows a piece of patchwork made from blocks which all have 3 strips in them. Each block is turned so that the edge with 2 seams adjoins a straight side of the next block. As you can see -
the pieces meet where they should.

There is a lot of talk about ¼ inch seam allowances when in fact this allowance should be a scant ¼ inch as even the thickness of the stitching and how the seam is pressed affects the end result. If your stitching is say one-eighth of an inch out it will actually make a difference of ¼ inch per seam as each seam has two pieces of fabric seam allowance. Imagine if you have a block with 6 strips stitched slightly wrong - it could be a real problem. Even a sewing machine with a quarter inch piecing foot (or special stitch to set at quarter of an inch) relies on how you line up the fabric with the edge of the sewing foot.

If you want to save yourself a lot of grief you can easily check how accurate your seam stitching is by doing the following test and adjust your stitching accordingly making patchwork more fun rather than a battle.

  1.  Fig 1
  2. Fig 2
  3. Fig 3

Take 3 strips of fabric cut at 2½ inches wide - these only need to be about 8 inches long. Figure 1. Stitch the three 8 inch strips together as shown. However you normally gauge your quarter inch seam, position the machine needle in the fabric just to the right of that making the actual stitching line a scant quarter inch by reducing the allowance by about the thickness of a machine needle. When these strips are joined, press the allowances all one way. Check the measurement across the width over the seams as shown in Figure 2. Your 3 strips are each 2½ inches wide so added together they total 7½ inches. Each seam has 2 edges of seam allowance of ¼ inch so that is ½ inch per seam which means the measurement should be reduced by the two seams stitched (1 inch) resulting in 6½ inches. Note when this block is joined to other blocks it will become a 6 inch square as it will lose the ¼ inch seam allowance on each of its sides.

If your measurement is less than 6½ inches it means your seam allowances are too big and need to be made smaller. If greater than 6½ inches the allowances are too small and need to be made larger. If you adjust this to get the measurement to 6½ inches your piecing will be a lot easier. In Figure 3 see the left hand block is about to be joined to the right hand block with one side having two joins and the other no join. As the lengths are the same measurement it makes joining them so much easier. For making blocks from these strips, after stitching together and pressing, cut accurately a length of 6½ inches from the 8 inch length to form a perfect square.

TIP: To make a quilt of these blocks cut strips across the whole width of the fabric and join in the same way. Cut into 6½ inches lengths to make the squares.

TIP: Where there are to be a lot of small pieces to be joined, use a fine cotton thread such as Metter 60 piecing/applique thread, actually their fine cotton Embroidery thread, which reduces the bulk in the seams.

Many blocks can be made using our Half Tabby Rolls which are strips already cut for you.