Do Your Blocks End Up Too Small?

May 30, 2011

Recently I’ve been working on a project that requires very accurate piecing. It got me thinking about the best way to get an accurate scant 1/4″ seam allowance (sa). The reason quilters strive for a scant 1/4″ sa is because we often press our seams to the side and this pressing takes up a thread or two (about 1/16″) to accomplish. When using an exact 1/4″  sa this small amount may not seem like much until it’s mulitiplied by 8 seams across the block. Now the block is 1/2″ too small and that is a problem.

The trick is to use an index card with 1/4″ lines. Cut the bottom of the card on the last line. Place it under the machine and lower the needle into the card so that the left side of the needle just “kisses”  the next line.

Now you simply need to place a piece of tape along the edge of the card, being careful not to tape over the feed dogs.

Remove the card and use the edge of the tape as your guide.

An added benefit is that this technique can yield identical seam allowances on different machines! Let me explain. There are times when I stitch on the same project on 2 different machines (like when taking a class). I can take the card with me, place the needle on the school’s  machine in the hole and tape next to it.

Voila – it works no matter what foot is on the machines. 

This is also a very handy way to keep group projects accurate. If you’re having a “sew in” at guild and many people are making blocks for the same quilt, use the same card to tape everyone’s machine and the blocks will fit together!

Do you have a different way you like? Is the foot for your machine a scant 1/4″? Please share any thoughts :-)!


  1. Clever idea. I like that it will work for group projects ( attention to detail being equal among participants :>)) I am going to mention this to my guild!

  2. Chris, thank you for reminding me of the scant 1/4 inch seam allowance. I was having a terrible time with my ‘Ribbon’ quilt runners turning out. They kept running off the ‘line.’ I took your suggestion and remembered to do a sa and tonight the strips ‘walked the line’. The only problem I had then was I was so excited to see if this worked, I forgot to put the right colored thread in the bobbin; so off-white on green floral wasn’t the worse I could do – thanks for the reminder tip.

  3. Great advice!

  4. I did a test and learned that my 1/4″ presser foot is a scant 1/4″. The scant sa is something I wasn’t aware of, so I’m grateful for the heads up.

  5. I think this is a great idea for group block projects, but does it matter so much to have that scant 1/4 inch for your own project if all the seams are consistent. You might not end up with the exact measurements the pattern lists but your blocks would all fit together.

    • Great question. It doesn’t matter if you’re doing a quilt with a single repeated block, because all the blocks will end up the same size. It makes a difference if you’re making a quilt that has 2 different blocks or a sampler with many blocks. If one block is a 4 patch with just one seam across that’s off by 1/16″, and the other is more intricate and has 5 seams across, the simple block will be 1/4″ larger. It’s something to be aware of :-).

      • what a great idea.I can’t wait to try this when I have to use 1/8″ seam allow.
        Thanks, Carol M

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