Objective: Sew clean, straight, secured seams and turn corners accurately on the Janome MC6650 — the three skills behind almost every sellable item.
Nearly every product you'll sell (zip pouches, totes, cushion covers) is built from straight seams, locked ends, and square corners. On the MC6650, start with the default straight stitch (stitch #1) and a stitch length of about 2.4mm for general seams. Set your seam allowance by lining the fabric's raw edge against the engraved guide lines on the needle plate — the 1/4" line for bag/craft work, 5/8" for garment-style seams. Keep your eyes on that guide line, not the needle; let the feed dogs pull the fabric while you only steer. To stop seams unraveling, secure both ends: the MC6650 has a one-step lock-stitch button (it sews a few stitches in place then stops), or you can hold the reverse lever to backstitch 3–4 stitches at the start and finish. For corners, use the needle-down button so the needle stays buried in the fabric, lift the presser foot, pivot the fabric 90°, drop the foot, and keep sewing — this keeps the corner from shifting.
Example: Make a 4"x4" square seam sample. Place two scrap fabric squares right sides together. Line the raw edge on the 1/4" guide. Press the lock-stitch button (or backstitch) to anchor. Sew down one side at steady speed watching the guide line. About 1/4" from the corner, press needle-down, lift the foot, pivot 90°, lower the foot, and continue. Repeat at each corner. End with a lock-stitch. You now have a sewn square with four even seams and crisp corners.
Try it: Cut four 4"x4" fabric scraps and sew two sewn squares: one at a 1/4" seam allowance and one at 5/8". On each, lock or backstitch both ends and pivot all four corners using needle-down. Then measure your seam allowance with a ruler at three points along one seam — aim for it to stay within 1/16" of the target.