There are 3 main things that can make your blocks come out wrong. Cutting is the first one. Make sure that you are accurately measuring & your ruler isn't slipping. Use the same ruler for the entire project, but if you do need to use different rulers, try and use all the same brand. Then next is pressing. Make sure that you are not pressing a tiny pleat into the seam allowance when you press. Also, press, not iron. An up and down motion will keep the pieces from stretching. And finally we talk about the size of the seam, however, you don't measure the seam you measure the resultant patch. If you use a quarter inch foot, you may still have to adjust your needle position. Also, fabric and thread weight will affect your seam so it's a good idea to check at the beginning of every project. Here's how to check:
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