Whip plaiting: the taper by rule.
Strand width from the core, lace length, and dropping pairs on plan, the plaiter's numbers before the first cut.
Strand width: the 4.6× rule
Over a core of diameter D, the total strand width ≈ 4.6 × D, so each strand ≈ 4.6 × D ÷ strand count. Why that number: at the usual plait angle the strands sit about 43° to the axis (4.6 ≈ 2π × cos43°). The plaiters' boards carry it; the forum threads test where it breaks, it runs short on thin cores, so an alternative is 1.5 × circumference (4.71 × D). The app switches to counting lace thickness (+ thickness per pass) when you ask it.
Lace length
Cut lace at 1.6 to 1.8 × the plaited length (the app's default: 1.7×). Measure on the first whip: the taper's drops give back a little.
Dropping pairs
| rule | what it does |
|---|---|
| drop in pairs | keeps an even count for round plaits, the usual 12 → 10 → 8 progression |
| "follow the taper" | each pair drops when the ideal strand count passes halfway between the current count and the next, the width stays even either side of the taper |
| the overlays | nylon overlays usually carry 12 to 24 strands (the whipmaker's own figures) |
Paracord plaited flat: 550 ≈ 4 mm wide, 325 ≈ 3, 95 ≈ 2, the estimates, and the field's editable: measure yours. The whole page = the app's WhipMath's own rules with their sources (the plaiting forums + the whipmakers).
A worked overlay
Plait a 12-strand nylon overlay on a core that measures 12 mm:
- Strand width: 4.6 × 12 mm = 55 mm of lace in total — 12 strands at about 4.6 mm each. The strands sit at about 43° to the axis, since 4.6 is 2π × cos 43°.
- The 1.5× circumference check: 1.5 × π × 12 ≈ 56.5 mm — the same answer within a millimetre, which is why both rules survive.
- Thin cores: the rule runs short on them — a 6 mm core wants more than 27.6 mm of lace reads well; the app's switch counts the lace thickness too, off by default.
- Lace length: 1.6–1.8 × the plaited length; the app defaults to 1.7×.
- The taper: strands drop in pairs — 12 to 10 to 8, keeping the plait round — and the app drops a pair where the ideal count passes halfway between the current and the next.
Nylon overlays usually run 12 to 24 strands, the whipmakers' own range; a 12-strand start on a 12 mm core sits right at the bottom of it, and the progression down follows the taper.
Mistakes worth avoiding
| the mistake | what it costs |
|---|---|
| 4.6 × D trusted on a thin core | the lace runs short; count the lace thickness or start the plait at the corrected figure |
| dropping strands one at a time | the plait goes lopsided; pairs keep it round — the whole reason for the convention |
| lace cut at the plaited length | 1.6–1.8× feeds the crossing; anything less pulls the belly short |
| strand count chosen before the core is measured | the count follows the measured diameter; the range is 12–24 for nylon and the width decides within it |
The app helps
The Whip page runs the taper: the measured core, the lace thickness switch, the strand progression with the pair-drops placed, and the lace cut at the 1.7× default. The bench's Knot TV shelf carries the plaiting films that show the pairs in motion.
Sources: the 4.6 × D rule and the 1.6–1.8× lace length from the whipmaking forums (the indygear plait-sizes thread; the leatherworker.net diameter thread that also flags the thin-core shortfall); the strand range from Canada Whips' construction page; the 43° is geometry (4.6 = 2π cos 43°). The pairs-drop and the halfway rule are the app's own conventions, labelled as such in the craft-facts document.