Objective: Learn the essential vocabulary and concepts of the Janome MC6650 so later lessons' instructions are instantly understandable.
Every instruction you'll follow in this course assumes a shared vocabulary, so lock these terms in now. The feed dogs are the toothed bars under the needle plate that grip and pull fabric backward as you sew; the drop-feed lever disengages them for free-motion work. The presser foot holds fabric against the feed dogs, and the presser foot lifter (a lever behind the needle) raises and lowers it—the MC6650 also has a knee lifter so you can raise it hands-free. The needle plate is the metal plate with seam-allowance guide lines etched in inches and millimeters. Stitch length means how far the fabric advances per stitch (longer = fewer, bigger stitches, e.g. for basting); stitch width controls side-to-side needle swing for zigzag and decorative stitches. Thread tension is the balance between the needle (top) thread and the bobbin (bottom) thread; the tension dial adjusts the top thread so stitches lock cleanly in the middle of the fabric rather than looping on top or underneath. The bobbin is the small spool of lower thread that sits in the bobbin case under the needle plate. On the LCD screen you'll see the selected stitch number, recommended presser foot letter (like 'A' for the standard zigzag foot), and the current length/width settings. Two buttons matter constantly: the needle up/down button parks the needle in or out of the fabric, and the reverse/lock-stitch button secures the start and end of a seam. Understanding these words means a phrase like 'select stitch 1, foot A, lower the presser foot, backstitch to lock' is a complete, executable instruction.
Example: Suppose a later lesson says: 'Set stitch length to 2.4, drop the presser foot with the knee lifter, sew along the 1/2" guide line, then press reverse to lock.' Decoded: choose a medium straight-stitch spacing (2.4 mm per stitch), raise/lower the foot using the knee lever instead of the hand lever, align your fabric edge to the needle-plate line marked 1/2 inch so your seam allowance is accurate, and hold the reverse button at the seam's end so the threads knot and won't unravel.
Try it: With the machine off, physically point to and say aloud each of these in order: feed dogs, presser foot lifter, needle plate guide lines, tension dial, bobbin case, needle up/down button, reverse button. Then write one sentence defining 'stitch length' and one defining 'thread tension' in your own words, and locate the 1/2" line on your needle plate.