Objective: Complete your first real sewing run on the MC6650 by winding a bobbin, threading the machine, and stitching a straight backstitched seam on scrap fabric.
The MC6650 is a computerized machine, so its numbered guides and buttons do most of the thinking for you. Winding a bobbin comes first: place a thread spool on the pin, pass the thread through the bobbin-winding tension disc, wind the end around an empty bobbin a few times, slide the bobbin onto the winding spindle, and push it right to engage. Pressing the Start/Stop button winds it automatically and stops when full. Next, thread the upper path by raising the presser foot (this opens the tension discs) and raising the needle to its highest point with the handwheel or needle up/down button. Follow the printed numbers 1 through the take-up lever and down to the needle, then use the built-in needle threader lever. Drop the bobbin into the case so the thread unwinds in the direction the diagram shows, and pull both threads to the back under the foot. Because the MC6650 has no foot pedal requirement, you start and stop with the Start/Stop button and control speed with the slider — set it low for your first seam. Backstitching (the reverse button) locks stitches at the start and end so seams don't unravel. Keeping the fabric edge aligned with a seam-allowance guideline on the needle plate gives you straight, even seams.
Example: Take a 6-inch square of woven cotton folded in half. Set stitch to the default straight stitch (pattern 1), move the speed slider to its slowest third, and lower the presser foot with the fabric edge at the 3/8-inch line on the needle plate. Hold the reverse button and stitch 3-4 stitches backward, release it, then press Start/Stop to sew forward about 5 inches, guiding — not pulling — the fabric. Near the end, hold reverse again for 3-4 stitches, press Start/Stop to halt, raise the needle and foot, and pull the fabric to the left to cut the threads. You now have a locked, straight seam.
Try it: Wind one bobbin, thread the machine top and bottom, and sew three straight seams on folded scrap cotton: one slow seam at the 3/8-inch guide with backstitching at both ends, then two more trying the 1/4-inch and 5/8-inch guides. Compare which seam allowance is easiest to follow and note whether your start and stop points are locked without loose threads.