Designing Woven Textile Drafts

Given a weaving request, work the pipeline in order — never skip stages:

1. Abstract → Explicit: Expand any block/profile draft into full threading, tie-up, and treadling.
2. Explicit → Physical: Calculate sett, take-up, width-in-reed, and yardage from the expanded draft + yarn specs.
3. Physical → Mechanical: Convert the verified draft triplet into the target loom's output format (lift plan, dobby file, treadle tie-up).

Example request: "Make a Summer & Winter draft for a 4-block profile, 8 shafts, using 10/2 cotton, for a table loom, finished width 20 inches."

Output order: (1) expand profile blocks into full threading/tie-up/treadling using Summer & Winter substitution rules → (2) calculate sett from 10/2 cotton WPI, compute ends needed for 20" + take-up allowance → (3) rotate the floor-loom-style tie-up into a direct table-loom lift plan.

Progress:

• Step 1: Identify which domain(s) the request touches (block expansion, physical calculation, loom conversion, or all three)
• Step 2: If a profile/block draft is given, expand it to an explicit threading/tie-up/treadling triplet
• Step 3: Validate float lengths against the structure's physical limits before finalizing the expansion
• Step 4: If yarn/dimension data is given, calculate sett, EPI/PPI, take-up %, width-in-reed, and total ends/picks
• Step 5: Check for floating selvedges or edge thread requirements
• Step 6: If a target loom type is specified, convert the verified triplet to that loom's mechanical format
• Step 7: Report any failure-mode risks (inverted face, unweavable floats, short/narrow cloth) before presenting final output

Step 2 detail — Block Expansion (Set 3 logic)

• Identify the weave structure family (e.g., Summer & Winter, Taqueté, Turned Twill, Shadow Weave) since the substitution template differs per structure.
• Map each profile block (A, B, C...) to its explicit unit (e.g., A → 1,3,2,3 tabby/pattern pairing; satin blocks → full satin sequence per shaft count).
• Non-unit or irregular blocks must be checked for even substitution; never truncate a block mid-unit.

Step 3 detail — Float Validation

• Flag any float longer than structure-appropriate limits (commonly 8-12 threads max for most yarns, shorter for soft/fuzzy fibers).
• A long float is a structural failure, not a stylistic choice — surface it explicitly rather than silently expanding.

Step 4 detail — Cloth Engineering (Set 4 logic)

• Derive sett from yarn WPI and structure density (balanced plain weave ≈ WPI/2; twills and unbalanced weaves need structure-specific multipliers — do not apply a flat percentage).
• Take-up and shrinkage are structure- and fiber-dependent: tightly interlaced plain weave take-up (~10-15%) is meaningfully higher than loose twill or float-heavy structures (~5-8%). State the assumption used.
• Compute: ends = (finished width × EPI) + take-up/draw-in allowance; total warp length = finished length / (1 - take-up%) + loom waste.
• Check reed availability: dent size must divide evenly into desired EPI (account for multiple ends per dent if required).

Step 5 detail — Selvedges

• Determine if floating selvedges are needed (common in twills, long-float structures) and add them outside the main threading repeat, unheddled or on a dedicated shaft.

Step 6 detail — Loom Mechanics (Set 2 logic)

• Table loom / direct-tie loom: lift plan = tie-up matrix transposed/rotated so each treadling pick becomes a direct shaft-lift row.
• Dobby loom: convert lift plan into peg/bar or digital dobby file format, preserving shaft-lift order exactly.
• Watch mirroring: a 90°-rotation error inverts twill diagonal direction or flips cloth face — double-check rotation direction against the original tie-up orientation.

Example 1: Input: "4-shaft point twill threading, treadled as straight draw, what's the tie-up for a table loom vs floor loom?" Output: Floor loom tie-up given as a 4×4 shaft/treadle matrix (one treadle per shaft combination). Table loom version: rotate matrix so each treadling row directly becomes a lift-plan row listing shafts to raise — no treadle intermediary. Note: table loom weaver lifts shafts directly per pick, so the "treadling sequence" becomes the lift-plan row order unchanged; only the tie-up→treadle step is removed.

Example 2: Input: "I have a 3-block Summer & Winter profile draft on 6 shafts. Expand it and tell me if it's weavable." Output: Each block expands to a 4-end unit (tabby-pattern-tabby-pattern using shafts 1-2 for tabby, 3/4/5/6 per block for pattern). Check: Summer & Winter floats are inherently short (max 1 pattern shot between tie-downs), so no float violation. Final threading given as explicit shaft-by-shaft sequence; tie-up and treadling given as standard S&W block-unit treadling (tabby alternation + block picks).

Example 3: Input: "10/2 cotton, want 18 inches finished width, balanced plain weave, 15-dent reed available." Output: Sett ≈ WPI/2 → 10/2 cotton is ~2100 ypp, approx 24 WPI → sett ≈ 20-24 EPI for balanced plain weave. 15-dent reed doesn't divide evenly at 1 end/dent; recommend 2 ends in some dents or sleying at 1/dent + 2/dent alternating pattern to hit ~22 EPI effective. Ends = 18 × 22 = 396, plus draw-in allowance (~8% for balanced plain weave) → round up ends and add floating selvedges if needed. Warp length = finished length / (1 - take-up%) + loom waste (typically 18-36 inches depending on loom style).