We've had some discussion about an accurate 1/4" seam allowance at my online group. It's a GREAT discussion to have. When I learned to quilt I took a 12 week course and I learned block construction, how to draft, and why there IS basic math, grids, and accuracy involved in quilt making.
So it does matter that your final block is the size.
And it's not correct to say they will 'work out' if the wrong size. Let me explain
If you are following a design, the sizes are there so that the quilt can be made properly. If you have a block, then a setting around it, if your block is too small or too large, it will not match the setting given. That means you will need to redraft the entire design to suit your incorrect block sizes. Or.. just make the blocks correctly.
Think of a puzzle. Each block is the size it is, so it fits in it's slot. If you an a puzzle piece that is too small it won't fill in the space allocated, right? Same with quilting.
Nailing an Accurate 1/4" seam allowance is the best thing you can do for your quilting skills.
I show you below how to determine your problem. In my patterns give you sub-measurements after sewing patches together.
If you are having inaccurate or inconsistent block sizes, then measure after each seam is sewn to see when and where the seam allowance is going wrong.
If you can get an accurate WRONG seam allowance, then you can get an accurate correct one too.
Even if you have a 1/4" foot for your machine you still need to check because the way you feed the fabric, your line of sight, and maybe the foot itself, might be slightly off. Causing an inaccurate seam. So you might need to adjust your needle position, try a different foot, or use another tool to help you achieve that accurate 1/4" seam.
Here is my easy test to see if you are set up correctly.
- Cut 3 squares 2 1/2" x 2 1/2". Use 2 different color fabrics
This is the 1/4" foot for my Babylock Destiny II.
I love the guide on it. Your machine may have a different foot, or no 1/4" foot.
Sew the 3 squares in a row, the the alternate color in the middle.
My Babylock's 1/4" seam foot sews a 'scant' 1/4" seam. Do you see how the seam is to the RIGHT of the line. When you fold over fabric it takes up a little space, so sewing with a seam just 'shy' of 1/4" is what works for many people, BUT your mileage may vary. So you need to test to see what is accurate.
I have this little 1/2" wide ruler that i keep by my machine to check things.
Now press the unit so the right sides are up for all 3 squares. Do you see how the seam allowance creates a ridge?
This is before i pressed it. when you press you need to have it flat. That way as you sew the units together they all are at the correct size.
now let's test it!
First I measure JUST the center block. It should be 2" wide.
Now i measure the entire unit. It should be 6 1/2" wide.
When I test I like to shift that ruler down and have a straight line across the top and bottom of the patchwork. There is a bit of a shadow on the top right, that's even. You can click the photo above for a larger image.
If your block is not accurate, then you need to work on things to find that 1/4".
- You can shift your needle to the right (although not with the foot I'm using).
- You can check your 1/4" foot to be sure you HAVE the 1/4" foot. Maybe you are using the wrong foot.
- If you don't have a 1/4" foot use another foot &, shifting the needle position should work for you. On one of my machines I used the open toe applique foot & shifted my needle position.
- You can put a layer of painter's tape on the right hand side as a guide once you know the foot & needle position.
My 6.5" rulers are the very best size for so many things. If you don't have one get one soon!!
You can Buy the 6.5" Quilting Ruler
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