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English Weaving
Simulator

Choose your threads. Weave your pattern.

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PATTERN

YARN COLOURS

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English Treadle Loom: Weave Drafts, Drawdowns and Cloth Geometry

Edit the draft (threading, tie-up, treadling) and watch the treadle loom weave exactly the drawdown it predicts. Then see what the cloth is made of: crimp, cover, weight and the tension in each warp thread.

Weave draft (click cells to edit)

Top: threading (which shaft each end is drawn through). Top right: tie-up (which shafts a treadle lifts). Right: treadling (the pedal order). Lower left: the drawdown, dark = warp on top. Click a threading column, a tie-up cell or a treadling row to change it; the pattern switches to Custom.

Yarn colours

Pick a role here, then click a colour swatch in the bar below the loom. Stripe order (ends and picks):

Warp stripe (ends of A then B)

Weft stripe (picks of A then B)

Cloth and loom settings

Cloth numbers

Warp thread tension at full shed

Warp tension vs shed opening (N per thread)

Crimp vs warp tension (Peirce, per cent)

Missions

Independent numerical checks

Also run outside the browser: node src/check.js (drawdown rules for plain, 2/2 twill and herringbone; interlacement index; Peirce solver against its closed form; shed stretch against the small-angle formula; mass accounting; cover factor).

Virtual loom for learning. The 3D loom shows 72 ends drawn about 15 times coarser than the real cloth numbers on the right. Yarn and tension constants marked [assumption] are illustrative. Not instructions for operating real equipment.

Controls

Drag / one finger: orbit; wheel / pinch: zoom; buttons Hero / Cloth / Shed / Side jump the camera (keys H C S).
Start weaving runs the pick cycle: treadle, shed, shuttle throw, beat-up, release. +1 pick single-steps. The pattern list and the draft editor change the cloth live.
Click a colour swatch to assign it to the chosen role (warp A/B, weft A/B).

The science

Draft and drawdown. End i is threaded through shaft s(i); treadle t is tied to a set of shafts; pick j uses treadle t(j). In a rising shed the end is lifted (warp on top) when s(i) ∈ tie(t(j)), otherwise it stays down and the weft shows. That one rule, applied to every cell, is the whole drawdown; the 3D loom and the cloth texture use the same function.

Floats and interlacement. A float is a run of consecutive picks over which an end stays on one side. Long floats make soft, drapey but snag-prone cloth. The interlacement index is the fraction of neighbouring cells where the over/under state flips: 1 for plain weave, 1/2 for 2/2 and 3/1 twills.

Cloth geometry (Peirce). A thread of spacing p between crossing threads makes a wave of height h with straight length l: p = (l − Dθ) cosθ + D sinθ, h = (l − Dθ) sinθ + D(1 − cosθ), D = d₁ + d₂, and the two thread systems share the height h_warp + h_weft = D. Crimp is l/p − 1. The page solves it by bisection; when the threads touch (jammed) θ reaches its limit. For a balanced jammed plain weave h = D/2, θ = 60° and crimp = 20.9%, which is the independent check.

Tension chooses the split. Peirce's equations leave one degree of freedom: how much of D the warp takes. Higher warp tension straightens the warp and pushes the crimp into the weft. The slider maps tension to that share linearly [assumption]. Crimp is scaled by the interlacement index [assumption: fewer interlacings, fewer waves].

Yarn. Diameter from linear density: d = √(4 tex · 10⁻⁶ / (π ρ φ)) with ρ = 1300 kg/m³ and packing φ = 0.6 [assumption, wool-like]. Cover per direction e = d/p; cloth cover e₁ + e₂ − e₁e₂. Areal weight adds both yarn systems including their crimp.

Warp tension in the shed. Opening a shed of height s stretches every warp thread: Δl = √(a² + s²/4) − a + √(b² + s²/4) − b (a = heddle to fell 0.30 m, b = back beam to heddle 0.95 m), small-angle Δl ≈ s²/8 (1/a + 1/b). Tension is T = T₀ + EA · Δl/(a + b) with EA = 3 N/tex · tex and breaking force 10 cN/tex · tex [assumptions]. Too much static tension plus a tall shed breaks the warp.

Honest simplifications. Four shafts and four treadles; rising shed only; perfectly uniform round yarn with no flattening, twist or fibre fuzz; no beat-up force or take-up elasticity; the 3D warp ends are schematic. Sources by type: Peirce, The Geometry of Cloth Structure (1937) and textile-structure textbooks; hand-weaving draft notation.

Models built with Blender (loom, shuttle, beater, room, yarn shelves) and rendered with Three.js.

English WeavingSimulator

English Weaving
Simulator