Do you know how to properly test your 1/4″ seam allowance?

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It is always good to test your 1/4″ seam allowance to be sure it’s accurate. If you change machines or maybe you just never tested it, this is a super simple way to be sure your seam allowance is 1/4″. 

pat sloan test your seam allowance

Even if you have a 1/4″ foot for your machine it might need to be adjusted. 

pat sloan test your seam allowance pic 1

Cut 3 squares 2 1/2″ x 2 1/2″.  Use different color fabrics

pat sloan test your seam allowance pic 2

This is the 1/4″ foot for my Babylock Crescendo.  I love the guide on it. Your machine may have a different foot, or no 1/4″ foot. 

pat sloan test your seam allowance pic 3

Sew the 3 squares in a row.

pat sloan test your seam allowance pic 4

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 most people.

I have this little 1/2″ wide ruler that i keep by my machine to check things.

pat sloan test your seam allowance pic 5

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!




pat sloan test your seam allowance pic 6

First I measure JUST the center block. It should be 2″ wide. 

pat sloan test your seam allowance pic 7

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 one, shifting the needle position should work for you.

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19 Responses

  1. Thanks for this article Pat. I will be doing the test today. I’m excited to be doing the SSampler and hope to learn a lot

  2. I have a Brother… same as Babylock……… and same foot…. i usually have to set my needle at 4.0 instead of 3.5 that is factory set. to get my scant 1/4 inch seam. it still works with the foot without breaking needles.
    i think it is amazing how many seasoned quilters in my guild don’t know this trick!!

  3. Oh my…I so appreciate you giving us tips to help with our sewing…thank you so much!!! Great tip!!!

  4. Thank you for the tips, Pat. I am going to sit down and enjoy “Teach Me to Machine Quilt” this evening. ~smile~ I am sure I will learn more tips there as well.

  5. What a great video on checking your 1/4″ seam. You do such a nice job of explaining it. Thanks.

  6. Thanks for the great info! Your studio looks fabulous since your redo. Thank you for all the fantastic blocks you come up with and so very graciously share them. You are appreciated! I’m having a fun time following along, although I sometimes have to play catch up!!!!

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