Objective: Calculate materials for a full-size quilt from 10" squares.
A 10" precut square finishes to 9" after seam allowances. A full-size quilt is roughly 84" x 90". Dividing 84 by 9 gives about 9 blocks across and 90 by 9 gives 10 down, so plan a 9x10 grid = 90 squares, trimming or adding a border to reach exact size. One 42-count precut pack (often called a Layer Cake) yields ~42 squares, so buy two to three packs or supplement with yardage cut to 10". Backing for a 84x90 top needs ~8" overage on all sides for the frame to clamp and for quilting drift, so cut backing roughly 100" x 106". That usually means 3 widths of 42"-wide fabric seamed, about 8.5 yards, or a single wide-back (108") at ~3 yards. Batting should also be ~8" larger all around: about 100" x 106", so a queen batting roll works well. Add 1/2 yard for binding (continuous 2.5" strips).
Example: Target 81" x 90" finished: 9 squares across x 10 down = 90 squares. Two Layer Cakes (84 squares) plus 6 extra 10" squares from a fat quarter covers it. Backing: 108" wide-back x 3 yards (108") gives 108x108, trimmed to 100x106. Batting: queen roll. Binding: 1/2 yard = ~10 strips of 2.5".
Try it: Write down your exact target finished size, then compute how many 9"-finished squares you need, how many precut packs that equals, and your backing and batting cut sizes with 8" overage.
Objective: Dial in an accurate 1/4" seam and pressing for a flat, square top.
Precut edges are often slightly pinked, so measure your 1/4" from the valley of the pinking, not the peaks, or your blocks shrink. Use the Janome 1/4" patchwork foot (O or the quarter-inch guide foot) and test a scant 1/4" seam: sew two squares, press, and the result should measure 18.5" for two across... actually 9.5" unfinished each means 18.5" pair; adjust needle position left/right until it does. Reduce presser-foot pressure slightly for precuts to avoid stretching, and use a 75/11 or 80/12 Microtex or universal needle with a fine piecing thread (50wt cotton). Chain-piece rows, press seams in alternating directions (or open for less bulk), then nest seams when joining rows. Set stitch length to about 2.0mm. Keep rows labeled so the layout stays square.
Example: Sew a test pair of squares with a scant 1/4". Press. It measures 18.25" instead of 18.5"—your seam is too deep. Move the needle one position right, resew, and confirm 18.5" before piecing the whole quilt.
Try it: Sew and press a two-square test seam, measure the unfinished width, and adjust needle position or foot until you consistently get 18.5". Note the setting you landed on.
Objective: Mount the layers and quilt with consistent stitches and good tension.
Load backing first with the top edge on the leader bar, wrong side up, centered and square—mark centers on leaders and backing so nothing skews. Float the pieced top (no leader attachment) or pin it to a third leader; floating is common with HQ frames and reduces top distortion. Smooth batting between. Baste the top edge across before free-motion quilting. For quilting thread use a 40wt cotton or poly top thread with a matching or finer bobbin; start with top tension around 3-4 and a 90/14 or 100/16 topstitch/quilting needle to prevent skipped stitches at frame speed. Set the HQ to a stitch-regulated mode (precision or cruise) so stitch length stays even as you move the machine. Test tension on the batting/backing scrap sandwich before touching the quilt, checking that no bobbin thread pokes to the top and no top thread dots the back. Advance the quilt one section at a time, re-smoothing and keeping even side tension with the clamps.
Example: You see small loops on the quilt back—classic sign top tension is too loose or thread isn't seated. Rethread the top with the presser foot up to seat it in the discs, bump top tension up half a number, retest on scrap, then resume.
Try it: Set up a small test sandwich of your backing, batting, and a top scrap on the frame, run a few passes in stitch-regulated mode, and adjust top tension until stitches look balanced on both sides. Record the needle and tension you used.