When I was a beginner quilter, I struggled with sewing an accurate quarter-inch seam allowance. I tried all the tricks, but my quilt block piecing was all over the place. It was super frustrating. My seam allowances were too big, so I cut my fabrics a tiny bit wider to compensate. That was equally disastrous.
Picture your favourite infomercial “before” hands thrown up in the air, eye-rolling reaction.
How did I finally get perfect, consistent, quarter-inch seam allowances for accurate piecing, perfect points, and beautiful quilt blocks?
Game Changer #1: The Flanged Quarter-Inch Presser Foot
Behold, my secret weapon in the Quest for the Consistent Seam Allowance!
Unlike some quarter-inch presser feet, it doesn’t merely give you a visual for 1/4″ from your sewing machine needle. It also has a little black guide or flange. You run the edge of your fabric right against the flange as you sew. If your sewing machine didn’t come with one, definitely see if you can pick one up. My Janome “patchwork foot” was about $20 and it made such an enormous impact in the accuracy of my piecing!
Go order one now. I’ll wait.
Game Changer #2: Measure Needle Distance
When I bought my flanged 1/4″ foot, I was told that of course it would work for my machine. I got home and popped it on, and measured the distance from the needle to the flange.
I measured by placing a quilting ruler under the presser foot, right against the flange. I then slowly turned the hand wheel to lower the needle until it was close enough to the ruler for me to see if it needed adjusting.
Guess what? It was actually a bit more than 1/4″. I had to adjust my needle a smidge to the right to get it accurate.
My sewing machine is an old mechanical machine, and I put it in straight stitch mode when I’m sewing patchwork. That meant I needed to turn a hidden screw to move the entire needle bar a bit to the right. My best advice, if you’re not sure how to get it spot on for your machine, is to take it to your sewing machine to your repair person and have them adjust it for you.
Game Changer #3: Measure Pressed Patchwork
If you’re not pressing your seams carefully, you might be losing a bit of fabric in the fold.
While your seam allowance might be a perfect 1/4″ from the stitch to the edge, losing a bit on the right side of your patchwork can also cause problems with accuracy.
Here’s an experiment you can do:
Carefully cut 6 2″ squares of fabric.
Sew 3 squares together with your perfect 1/4″ seam allowance, then press the seam allowances to the side
Sew the other 3 squares together; press this set open.
Measure the finished result of both. If they’re not 5″, but your seam allowances are 1/4″, can you change your pressing technique to keep things accurate?
Game Changer #4: Press & Starch Before You Cut
I’m not a pre-washer of quilting fabric. No amount of evangelizing will change my mind on this. But when accuracy counts in my patchwork, I will always starch and press my fabric before I cut.
Not only does starch avoid distortion when you’re sewing on the bias, the act of spraying and then pressing your fabric also does a bit of pre-shrinking for you. I’ve done it the other way around, cutting before I starched, and there was a noticeable amount of shrinkage after pressing. 1/16″ to 1/8″, which will definitely add up!
Sewing Science Homework
What do you think? Give these 4 tips a try and see if your patchwork precision improves! Let me know how it goes in the comments. Happy stitching!