When it comes to accurate piecing, there is a lot of talk about accurate cutting and an accurate scant quarter-inch seam allowance. It is absolutely true that if you don't have those two things going for you, your piecing will not be accurate. However, there are a few other pointers I'd like to share that have helped me achieve more accurate units for my quilt blocks. Keep in mind, these tips are just things that have helped me. The quilt police aren't going to come knocking if you choose not to do these things.
I am a firm believer in starching my fabric before sewing. I use Faultless Heavy Finish Starch from Walmart and go through countless cans when prepping my fabric. The idea is to really saturate the fabric, let it dry naturally, and iron it flat before cutting it. The fabric won't be floppy and linty anymore. It will be like sewing with little paint chips or light cardboard. I believe starching really adds to accuracy in sewing. It also shrinks the fabric ever so slightly in one direction, which isn't really an issue. Just be aware that will happen.
I also think it is important to check the size of your pieced units prior to sewing them into a block. Often they will be "off" just a smidgen, but those smidgens add up. Many people (including me) like to make their block units just a bit too big, then trim down to size. You can use any old ruler for checking size and trimming the unit, but there are a number of speciality rulers that I have collected over time that I really like to use. The hourglass trim tool above is Cute Cuts by Lori Holt. They come in a slew of sizes and I have them from 2 1/2" up to 16 1/2"! Like I said, I didn't buy them all at once, that is for sure. You can line up the corner seams and the center and trim the excess away for a unit that is dead on accurate. There are tools for trimming Flying Geese units and Half Square Triangle units as well. I like the BlocLoc brand, but there are others way less expensive.
Press your seams open for a flat block. Use a wool pressing mat for even better results. Oh, and I am a big fan of steam, lots of it. I never used to bother with pressing seams open, but now that I do it nearly all the time, my blocks are so much more precise.
Use a clapper. No, that doesn't mean to have the kids stand in the doorway and cheer you on. A clapper is a wooden block that you place on a freshly ironed block or block unit. The wood absorbs the heat and some kind of magic happens that makes your seams lie even flatter. I swear by these ever since I discovered them.
Pin. I have always been a pinner. I watch quilters like Jessica Dayon who get great-looking blocks without pinning or even ironing after every step, but I am not that good. I need to pin to get those points to come out and to have my seams line up just right.
Hope you got something out of this post that might help you with more accurate piecing.
Did you notice that there might be a new project in the works?