Objective: Learn the essential terms and concepts for the Janome MC6650 so that every later instruction in this course is immediately understandable.
Before you build products to sell, you need a shared vocabulary so instructions never confuse you. On the MC6650, the needle moves up and down to form stitches; the feed dogs are the small metal teeth under the presser foot that grip the fabric and move it along automatically — you guide, you don't push. The presser foot holds fabric flat against the feed dogs; you raise and lower it with the presser foot lever behind the needle. Stitch length (measured in millimeters, roughly 0.2 to 5mm on this machine) is how far the fabric advances per stitch: short lengths (2mm) are strong and tight, long lengths (4mm+) are used for basting or gathering. Stitch width applies to zigzag and decorative stitches and controls how far the needle swings side to side. Thread tension is the balance between the upper thread and the bobbin thread; correct tension locks the two threads in the middle of the fabric layers, while wrong tension shows loops on top or bottom. The bobbin is the small lower spool; the MC6650 uses a top-loading drop-in bobbin. Seam allowance is the distance between your stitching line and the raw edge of the fabric — a 'standard' home-sewing seam allowance is often 1cm (3/8in) or 1.5cm (5/8in), guided by the lines on the needle plate. On the LCD screen you select a stitch number and the machine suggests a foot, length, and width, which you can adjust with the plus/minus buttons. Backstitch (the reverse button) sews backward a few stitches to lock a seam so it doesn't unravel. Knowing these terms means that when a later lesson says 'set stitch length to 2.4, use a 1cm seam allowance, and backstitch at both ends,' you can do it without hesitation.
Example: Suppose a later lesson asks you to sew a tote bag side seam. Translating the vocabulary: you lower the presser foot onto two fabric layers, line the raw edge up with the 1cm mark on the needle plate (seam allowance), confirm the LCD shows straight stitch with stitch length 2.4mm (strong but not bunched), press reverse to backstitch three stitches, release and sew forward while the feed dogs pull the fabric, then backstitch again at the end. Every bolded term there is one you just defined.
Try it: Sit at your MC6650 and physically point to and name aloud: the feed dogs, presser foot lever, bobbin area, reverse/backstitch button, and the LCD stitch-length display. Then set the machine to straight stitch and change the stitch length from its default to 2.0mm and back to 3.0mm using the plus/minus buttons, watching the number change on the screen. Finally, find the 1cm and 1.5cm seam allowance lines on your needle plate.