A SCANT 1/4″ SEAM RECOGNIZES THREAD TAKES UP SPACE!
For this important step, you will need: scrap fabric, cutting ruler, painters’ tape, and 2 strips of fabric 1 1/4″ x 3″.
First, check and see if the plate under your pressure foot has markings for 1/4″, 1/2″, or maybe 5/8″. That is a good place to start, however extending that mark 3 or 4 inches in front of the needle will help you keep your fabric straight and therefore accurate and consistent seams. Place the tape in line with the 1/4″ marking and using a straight edge on the scrap fabric practice sewing a straight line using the tape as your guide. If your machine does not have the markings I referred to, place your cutting ruler under the foot with the needle tip lightly touching the 1/4″ mark next to the right edge of the ruler. Place the tape along the ruler (be sure it is straight) and do the scrap practice stitching exercise.
Once comfortable you can follow the tape guide, take your two strips of fabric 1 1/4″ x 3 and placing one on top of the other with edges meeting, sew down the long side following the guide. When completed, press open by lifting the top fabric and gently smoothing it away from you. Now, measure the width of the two fabrics. What did you get? If you followed the tape guide and it is 1/4″ from the needle, your measurement should be exactly 2″. If it is wider, your tape is too close to the needle; narrower means your seam is too wide. Hello, seam ripper! Adjust the tape until you get 2″ exactly. The tape will be in the exact place for a quarter inch seam.
But what about a scant quarter inch seam? Look at your thread. It has width, some more than others. The scant quarter inch seam allows for the thread to take up a “scant” amount of seam, so rather than sew exactly on the 1/4″ mark, sewing a thread width away means when the seam is pressed the thread width is part of the seam and therefore 1/4″ seam is the result. Sewing scant quarter inch seams are significant in keeping with the design of a quilt and finished block measurements. Example – 2 different color squares are layered and a corner to corner diagonal line is drawn with another on each side 1/4″ away. Sewing on the 2 outer lines and cutting on the center line, 2 half square triangle blocks are made. Pretty cool until you go to line that square up with a square that should be the same size as the 2 started out to be and can’t because that square (the one made up of the 1/2 square triangles) is smaller. Why? Because sewing ON the line did not give any space for the thread, so it took up block space instead of seam space where it belongs! By sewing just a thread width away from the seam toward the cut line will make up for the space the thread takes, and your squares will all be the same.
For those with a machine that lets you adjust the needle left or right, no need to move your tape quide (add layers of tape to build a better edge for the fabric to go along). One click is all you need but think it through to be sure you go in the right direction or you and your new BF the Ripper will be doing some time together!
If you can’t adjust the position of the needle, just make your guide line a thread width closer to the needle and you will have it. Once you have the test mastered and you are getting 2″ as your measurement, add several layers to your tape guide so your fabric will have more of an edge to slide along.
Online, you can find plastic stick on strips, magnetic edges, and other gadgets to help you get the 1/4″ seam. I’ve tried a few for my students and myself. Some are better than others, so you and your wallet will have to decide if painters’ tape isn’t your style. Mole skin found with other Dr. Scholl products in the local markets and drug stores will also adhere nicely. Some machines come with or you can purchase a guide that screws on and is adjustable for any width of seam – nice if you do garment sewing with 5/8″ seams and then want the 1/4″ seam for piecing. Check around at your local quilt shops and fabric stores along with sewing machine stores. You will be amazed at what is out there.