Leanne’s Blog

That 1/4” seam!

Hi Quilters

To kick off my new blog, I thought it might be handy to go over some tips and tricks that we all kind of know but may need a refresher every now and then.

We’ve all had blocks that haven’t turned out to be quite right. They can often be too small or too large and therefore cause problems in the overall design. When it comes time to sew all our blocks together, they just won’t fit or line up! It can be so frustrating!

The problem can be a number of things but often it’s our 1/4” seam that’s to blame. As one of the foundation skills for quilters, it’s important to get the seam spot on.

So lets do a test…

Firstly, you need a 1/4” foot that is designed for your machine. My Bernina has three feet described as 1/4” feet: #37 foot without guide, #57 foot with guide, and #97 foot with separate screw on guide. I love my #37 because having no guide on the side means as long as I’m using a straight stitch I can use it for normal sewing as well. I find the #57 with the guide doesn’t go cross country too well lol.
It doesn’t matter which foot you have really, they are all designed to assist you with an accurate seam allowance.

However, we must remember that all machines are different and all quilters are different so just having the right foot is no guarantee of accuracy. Better to conduct the following experiment to work out your own unique seam allowance for your machine.

So, I’ve cut three sets of (3) 2” strips to demonstrate. They need to be an accurate 2” wide , the length is not important.

Oh just look at that messy sewing table! Never fear its creative mess!

For the first set, I’m going to place my fabric under the foot so I can just see the edge of my fabric poking out from underneath.

This is where I find most quilters place their foot on the fabric. I’m going to sew the three strips together, press the seams to the centre, and then measure.

For the second set, I’m going to place the edge of the fabric directly under the edge of the foot, so I can’t see the edge of the fabric but I know it’s there because I can see it feeding through from the front.

Again press and measure.

For the third set, I’m going to place the edge of the fabric more to the left, way under the foot.

Again press and measure.

So, what is the result?

We would expect the sewn fabric with an accurate 1/4” seam to measure 5” because 2” + 2” +2” = 6” – 1” (1/2” for each seam) to give us a measurement of 5”. We call this 5” unfinished because the very outer edges haven’t been sewn yet.

Here are the official results:

You can see from the picture that visually there appears to be very little difference in the seams but….

Our first set measures just under 5”. Our seam allowance was a fraction, only a millimetre really, too wide! We tend to forget that it’s not just the seam that counts but when we press over those seam allowances, that uses up another millimetre making the block too small. You can imagine over many seams this can make a huge difference.

The second set is exactly on 5”. Perfect! So placing the fabric directly under the foot is how I will get a precise 1/4” on this machine!

The third set measures 5 1/4”, way too big! The seams are too narrow!

I hope this helps you understand how important the seam allowance can be when piecing. Just by doing this little test with some scrap fabric can make such a difference.

Have you heard about my new mystery quilt-along starting on Monday 12th October 2020? Click here for more info.

Until next month

Happy sewing
Leanne x