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The perplexing scant ¼” seam.

Updated: Aug 29, 2023

What is it?

Why do we need it?

How do we achieve it?

Patchwork blocks are like puzzles; the pieces need to fit together perfectly, with a ¼” seam. Have you ever sewn a patchwork block together, trying your best to be as accurate as possible, only for the block to turn out too small?

You may need to use a scant 1/4" seam when making patchwork blocks and this is why.......

Before you begin any patchwork project, sew three 1 ½” strips of fabric together with a ¼” seam allowance, press the seams and measure the centre strip. The centre strip should measure 1” wide, right?

Most times, this isn’t the case, it’s a fraction smaller.

Why does this happen?

The fold over of the seam and the thickness of the thread can all take up a tiny bit of space in the seam as shown in this picture below. (Fabric and thread thickness can really affect the outcome of the seam, a 50 weight thread is recommended for sewing patchwork blocks).

How do we put a measurement on scant?

Let’s go back to the photo and try and measure it.

The pink centre strip looks almost 1/16th of an inch less than 1” wide so you’d have to divide that by 2, to allow for the seam on both sides, so that's 1/32nd of an inch.

I googled a length converter to see what that amount is in metric and this is what I found.

It’s less than 1 millimetre!

That’s tiny, but it’s the small things that count when it comes to accuracy!

The photo below shows a regular ¼” seam in black thread and a scant ¼” seam in the red thread, so as you can see, the difference between them is scant so I suppose that’s how the scant ¼” seam got it's name.

How to achieve a scant ¼” seam.

First of all, work out your regular ¼” seam.

To sew a ¼” seam, use a ¼” foot or a ¼” foot with a guide. These feet are normally an additional accessory that are available to purchase.

If you don’t have a ¼” foot, move your needle over to the right so that the distance from the edge of the foot to the needle is a ¼”. You can measure this with a tape measure or a ruler.

If using a ruler, be extra careful to not accidently hit the foot control and break the needle.

Refer to your sewing machine manual to see how to move the needle position. If you have a computerised machine, try moving the needle with the stitch width button while you are set on straight stitch. Make sure that the needle is in the highest position when moving your needle. It will move by a tiny amount each time.

Please note: Never move the needle position if you have a straight stitch plate attached. This plate has 1 small hole for the needle to fit when straight stitching with the needle in the centre position.

Some sewing machines will have the ¼” needle position as a stitch that you can select in the quilting menu if your machine is a “quilting” machine. This is to use with the standard foot on your machine.

If you cannot move your needle position, measure the ¼” from the needle and mark with masking tape or painter’s tape. You can add layers of tape to make a ridge for the fabric to run along while you are sewing. Position the tape just in front of the feed dogs.