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How to join quilt blocks

by | Sep 27, 2020

This post takes you through everything you need to know about joining your quilt blocks into a complete quilt top, ready for backing and binding.

I’ll cover joining regular blocks as well as split blocks.

Wait, what the heck is a split quilt block?

I’m talking about those blocks that combine to make one larger block. If you’ve seen A Starry Night in the Forest quilt, you’ve seen a couple of these split blocks.

Block 6 is made in two halves, with the top of the large tree in one hooping, and the bottom in another.

Block in two halves

Block 7 is a quarter of one large star, so all four need to be joined to make the centre block.

Starry night centre star in four quarters 

Joining split blocks is just like joining other quilt blocks, except you’re not only aligning the block corners. With a split block, you also need to match the appliques perfectly across the seam, so that the end result looks like one big block.

Preparation for joining blocks

Start with an accurately trimmed block. It makes it so much easier to stitch seams in the correct place if your blocks are square and true.

I design all my blocks with an outline around the quilting stitches, which is where the seam line will be. I call it the guide line.

This outer guide line of stitches gives you something to match up when you join your blocks. It’s also an excellent guide when you trim.

Trimming

The first thing to do after you unhoop your block is to cut away all the excess batting and stabiliser. These pictures show how I do that with a ruler and rotary cutter. You can use scissors of course.

How to trim quilt blocks ready for joining

Now decide on the width of your seam allowance, and trim all your blocks the same. I use 1/4”, that’s just what I’m used to. You might prefer 1/2”. The important thing is that you make them all the same width.

Clear ruler and rotary cutter

Both these items are in my quilter’s essential toolkit. If you haven’t used a rotary cutter yet, you really should.

Use the clear ruler to line up along the outline guide stitch, and trim off the excess fabric.

Trimmimg blocks ready for joining

Mark the line and use scissors.

This is a perfectly acceptable way to trim your blocks, but it will take longer and takes more care to be accurate.

Measure the width of the seam allowance with a seam guide or ruler along the outline guide stitches, use a straight edge to mark the line, and cut with scissors.

Joining

Put your blocks face to face, and pin either end, parallel with the seam line and a couple of centimetres away. (This leaves space for the sewing machine foot)

Pin quilt blocks together

Pinning either end means your corners will line up perfectly.

Pins in between the two ends should be put in perpendicular to the seam. If your blocks have design features that need to match, pin just before them.

The pin holds the blocks together at the crucial point, plus it reminds you that there’s pattern matching coming up.

Lining up matching designs

Tip: Pinning two bulky layers can make them shift. If you put the pin through the seam of the top block, and a fraction below the seam on the bottom block, they will match up once they are pinned.

Stitching

Use a straight stitch, and lengthen the stitch. On my Janome the standard stitch length is 2.4. I increase it to 3.0 for block joining.

Use a clear foot if you have one, and move the needle over to the right so that the whole of the width of the foot is on the quilt layers. This holds them together and as you sew and makes it easier to keep a straight line. Having half the foot on the right of the seamline means it’s in fresh air and the seam is harder to control.

Aligning the foot on your quilt blocks

See how that pin is clear of the foot but still keeps the ends aligned?

Reduce your machine speed. You’ll get better control if you sew more slowly. And I like to have both hands free to guide the block, especially as I might want to stop and start as I go, so I use the foot pedal and not the stop/start button.

Stitch just inside that outer guide line. I set my needle position so I’m sewing about 1mm to the left. Your guide line will be hidden when you open out the blocks.

quilt block seam

Tip for lining up your seam:

Pick a feature on your machine foot and keep the guide stitches lined up with it. Mine has a groove to the right of the needle, and if I move my needle all the way to the right and sew with the guide stitch under the groove, I get a perfectly aligned seam.

You can use the lines marked on your needle plate, or stick coloured tape to the bed of the machine. Find something to use as a guide and keep your eye on it.

If you’re not happy with your seam, rip it out and do it again.

Tip: I use embroidery thread and bobbin thread to join my blocks. It’s perfectly strong enough for a quilt, (unlike seams in clothes, these seams aren’t under strain), and you can quite literally rip a seam apart if you have to, without damaging the block.

Of course, if you prefer to use a seam ripper or scissors, that’s fine too.

As you get more experienced, you’ll make fewer mistakes.

Pressing

When you’ve joined your block, and you’re happy that everything matches up, you’ll need to press the seam so it lies flat.

You can press to one side, or press open. There are pros and cons to both.

Pressing open distributes the bulk either side and means the seam lies flatter. But as there’s no batting or stabiliser in the seam allowance we’re only talking a couple of layers of cotton. It’s easier to press seam allowances open if they are wide. Narrow allowances are a fiddly pain to press open.

Pressing to one side means all the seam allowances lie on one side of the seam. It’s faster, and less fiddly, especially if you use a 1/4” allowance. Plus it makes matching seams a piece of cake because it allows you to lock them together. 

I press to one side. The extra bulk on the side I press to doesn’t seem to make any difference to the look of the finished quilt.

Sewing multiple blocks together

Once you’ve joined blocks into rows, you’ll need to join the rows.

Use the same pinning technique for joining two rows of blocks. Pin each end parallel to the seam.  This time pin along the seam just before each point where blocks meet at the corners.

Lock matching seams.

If you’ve pressed to one side, you can use the seam allowances to lock seams together and ensure they match perfectly.

Tip: accurate block matching will transform your quilt, so it’s worth taking time over it.

I pin just before the join, so I know when I’m almost there and I can slow the machine right down to feel with my fingers when the two seams align in the right place. You’ll get to know what that feels like.

lock seam allowances together

Tip: alternate the direction you press seams for each row of blocks. You’ll get perfect matching corners where 4 blocks meet

Pin at other matching features and anywhere you want to keep the outline guide stitch together.

Tip: Double check that everything’s lined up correctly by matching the raw edges on the right as you sew. This is where your accurate trimming pays off

If I’m making a large quilt, I tend to join groups of blocks together rather than long rows.

It’s much easier to manage them under the needle.

Finally: remember, practice makes perfect. The more quilts you make the better and faster you’ll get.

And nobody else will notice your mistakes. Each wobble and imperfection is what makes your quilt unique. Other people will only see an amazing work of love and dedication.

You can download this post as a PDF

Next: adding a backing to your quilt.

Tagged with Starry night quilt

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