Objective: Perform three intermediate finishing techniques on the Janome MC6650 — accurate 1/4-inch seams, controlled topstitching, and an automatic one-step buttonhole — so your sellable items look professionally finished.
Moving from basic straight seams to saleable quality is mostly about control and consistency, and the MC6650 gives you tools for both. First, needle position: press the left/right needle-position buttons to shift the straight stitch, letting you ride a fabric edge along a fixed guide line for perfectly even seam allowances. For a true 1/4-inch seam, install the quarter-inch (patchwork) foot O; its edge acts as a wall you push fabric against, which is essential for quilting and small goods. Second, topstitching — the visible decorative/functional stitching near an edge. Lengthen your straight stitch to about 3.0-3.5mm, use the edge of the regular foot or the markings on the needle plate as a guide, and slow the foot pedal for straight lines around corners. A longer stitch looks intentional and lies flatter. Third, the one-step buttonhole: snap on the automatic buttonhole foot (R), pull the foot's sliding plate back and seat your button in it, lower the buttonhole lever behind the needle bar, select the buttonhole stitch, and the machine measures the button and sews both sides plus the bar tacks automatically, stopping on its own. Always test each technique on a doubled scrap of your actual project fabric with the same interfacing before committing to the real piece.
Example: Making a lined zip pouch to sell: switch to foot O, set needle center, and sew the 1/4-inch side seams by running the fabric edge against the foot's right edge — your seam allowance stays uniform so the lining fits. After turning it right-side out, change to the standard foot, set stitch length to 3.2mm, and topstitch 1/8 inch from the zipper by aligning the edge with the inner toe of the foot, going slowly past the zipper pull. The result is a crisp, store-quality finish on both the structure and the visible detail.
Try it: On a doubled 6x6-inch scrap with lightweight interfacing, do all three: (1) sew a 1/4-inch seam down one side using foot O and the foot edge as your guide; (2) topstitch a line 1/8 inch inside another edge at 3.2mm stitch length; (3) attach foot R, insert a shirt button, lower the buttonhole lever, and sew one complete automatic buttonhole. Measure your 1/4-inch seam with a ruler and check that it stays within 1/16 inch of accuracy the whole length.