Objective: Set up and control the MC8200 for straight-line walking-foot quilting through a full three-layer sandwich, and know how to shift into free-motion mode.
At the intermediate stage you move from piecing flat fabric to quilting a sandwich (top, batting, backing). Three layers feed unevenly under a standard foot, causing puckers and shifting. The MC8200's AcuFeed Flex dual-feed system (the walking foot) grips both top and bottom layers so they advance together. Attach the AcuFeed holder to the machine's mounting bar and clip on the dual-feed foot (use the wide 'VD' foot for quilting). Select a straight stitch, and the machine will prompt or allow a slightly lengthened stitch (about 2.8-3.2mm) which looks cleaner on quilts. Keep feed dogs UP for walking-foot work. For free-motion quilting (stippling, curves) you do the opposite: remove the walking foot, attach the free-motion/darning foot, lower the feed dogs using the drop-feed lever, and you move the fabric by hand while the machine stitches in place. Tension matters more now: with cotton top thread and matching bobbin, aim for upper tension around 4; if you see bobbin thread pulled to the top, lower the number; if top thread shows as dots underneath, raise it slightly. Always test on a scrap sandwich made from the same fabrics and batting before touching a saleable quilt.
Example: You baste a 12-inch practice sandwich (quilting cotton, 80/20 batting, cotton backing). You attach the AcuFeed Flex VD foot, set a straight stitch at 3.0mm length, tension at 4.0, and stitch a line. The backing shows the top thread pulling through as small dots. You raise upper tension to 4.5, re-stitch, and now both sides show smooth, balanced stitches with no puckering because the dual feed moved all three layers evenly.
Try it: Make a 12-inch three-layer scrap sandwich with the same materials you plan to sell. Attach the AcuFeed Flex walking foot, set straight stitch at 3.0mm, tension 4.0, feed dogs up. Sew three parallel lines. Inspect the back: adjust upper tension up or down by 0.5 until top and bottom stitches look identical. Then remove the walking foot, attach the free-motion foot, lower the feed dogs, and stitch a short loopy line by moving the fabric yourself to feel the difference.