The3DG

Knits & fabric · Test cube 2

Rib knit

The same stitch, narrower and taller: the stretchy columns of a sweater cuff.

Presented by SpoolYarn comes on a spool too. I feel very at home here.
× 1.00
1.1 mm
135°
  • Prints well with a 0.4 mm nozzle.

25 mm, with your size and depth. Prints upright, no supports. About 4 MB.

Good for

Cups, sleeves and anything round and tall.

Print notes

  • Depth 0.4 to 1.5 mm for a 0.4 mm nozzle (as written: 1.1 mm).
  • Best on walls, printed upright. On a flat top, use thin layers (0.12 mm or less).
  • Fade it out over the bottom 3 mm so the first layers are flat and stick to the plate.
  • Not printed yet: these notes come from the geometry. The test cube will tell us more.

The formula

The real code this page runs: give it a point (U mm across, V mm up) and it returns the height there, in mm. Push the surface out by that much and the texture is real geometry.

function ribKnit(U: number, V: number) {
  return stitches(U, V, 4.2, 6.8, 1.0);
}
The helpers it uses (stitches, clamp, srand)
/** Packed V stitches: two plump leaning legs per cell, with the yarn's twist running along each. */
function stitches(U: number, V: number, sw: number, sh: number, amp: number) {
  const row0 = Math.floor(V / sh);
  const col0 = Math.floor(U / sw);
  let h = 0;
  for (const dr of [-1, 0, 1])
    for (const dc of [-1, 0, 1]) {
      const r = row0 + dr;
      const c = col0 + dc;
      const s = U / sw - (c + 0.5);
      const t = V / sh - (r + 0.5);
      const jx = 0.05 * srand(r, c, 1);
      const jy = 0.05 * srand(r, c, 2);
      const ja = 1 + 0.08 * srand(r, c, 3);
      for (const side of [-1, 1]) {
        const cx = side * 0.21 + jx;
        const cy = 0.05 + jy;
        let dx = side * 0.42;
        let dy = 0.91;
        const n = Math.hypot(dx, dy);
        dx = dx / n;
        dy = dy / n;
        const u = (s - cx) * dx + (t - cy) * dy;
        const w = -(s - cx) * dy + (t - cy) * dx;
        const r2 = (u / 0.64) ** 2 + (w / 0.3) ** 2;
        const bump = clamp(1 - r2, 0, 1) ** 0.5;
        const ply = 1 - 0.1 * (0.5 + 0.5 * Math.sin(2 * Math.PI * (u * 4.0 + w * 2.0 * side)));
        h = Math.max(h, amp * ja * bump * ply);
      }
    }
  return h;
}
function clamp(x: number, lo: number, hi: number) {
  return Math.min(Math.max(x, lo), hi);
}
/** Random in -1..1 for one crochet stitch. */
function srand(r: number, c: number, k: number) {
  const x = Math.sin(r * 127.1 + c * 311.7 + k * 74.7) * 43758.5453;
  return (x - Math.floor(x)) * 2 - 1;
}

Printed

Test cube 2 is waiting for the printer. Its photo goes here.