Objective: Sew a straight, anchored seam at a consistent 5/8" seam allowance and pivot a square corner on the Janome MC6650.
Three techniques form the backbone of nearly every saleable item: a straight seam, a secure backstitch, and a clean corner pivot. Start by selecting straight stitch (pattern 1) on the MC6650's touchscreen; the default stitch length of 2.4mm is ideal for seams. Seam allowance is the distance from the needle to the raw fabric edge. Rather than watching the needle, keep your eyes on the edge of the fabric as it rides along the engraved guide lines on the needle plate to the right of the presser foot. The 5/8" line is the industry standard for garments and many home-decor items. To anchor a seam so it won't unravel, use the backstitch (reverse) button: sew forward 2-3 stitches from the fabric's top edge, hold reverse to stitch back to the edge, release, then sew forward normally. Repeat the backstitch at the seam's end. The MC6650 also has a programmable auto-lock/thread-cut, but learning manual backstitch builds control. For a corner, stop with the needle DOWN in the fabric (press the needle up/down button so it finishes embedded), lift the presser foot, rotate the fabric 90 degrees around the needle as a pivot point, lower the foot, and continue. Keep a steady, moderate foot-pedal speed—consistent speed produces consistent stitches.
Example: Take a 6"x6" scrap of woven cotton. Line the right-hand raw edge against the 5/8" needle-plate guide. Lower the presser foot. Sew 3 stitches forward, press and hold reverse back to the edge, release, then sew forward keeping the edge on the 5/8" line. About 5/8" before the bottom edge, press needle-down so the needle stays in the fabric, lift the foot, rotate the scrap 90 degrees, lower the foot, and sew the next side. At the final corner-free edge end, backstitch 3 stitches to anchor, then lift the foot and clip threads. You now have an L-shaped seam with square corners and locked ends.
Try it: Using two stacked 6"x6" cotton scraps, sew a seam down all four sides at a 5/8" allowance, pivoting at each corner with needle-down, and backstitching at the start and finish. Then measure your seam allowance with a ruler at several points—aim for it to stay within 1/16" of 5/8" the whole way around.