Block Substitution

What It Does

Block Substitution takes a simple profile draft and expands it into a full weave structure by applying a weave template. Your profile draft defines the block layout — which blocks are active where — and the template defines how each block is actually woven (the specific interlacement, tie-down threads, and shaft assignments within each block).

This is how weavers traditionally work with block weaves: you design the pattern at the block level (simple, fast), then substitute in the actual weave structure (Huck, Overshot, Summer and Winter, etc.) to produce the full threading, tie-up, and treadling needed at the loom.

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Location

• Ribbon: Design tab > Section Assembly group > Block Substitution button (toggle)

The Block Substitution panel opens as a dockable tool window.

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The Panel

Template List

The upper portion shows all available weave templates in a list with columns:

• Name — Template name (e.g., "Spot Bronson," "Summer & Winter 4-Block")

• Type — Weave category (Huck, Overshot, Summer and Winter, etc.)

• Shafts — Number of shafts in the template pattern

• Treadles — Number of treadles per block

Click a template to select it and see its details in the info panel below.

Template Management

Add — Create a new template entry. Opens the template editor.

Edit — Modify the selected template's settings.

Delete — Remove the selected template from the library.

Info Panel

The lower portion shows details about the selected template:

• Template Name — Bold, full display

• Type — The weave family

• Stats:

  • Shafts (in the template)

  • Treadles per Block

  • Tie Shafts (warp tie-down thread count)

  • Tie Treadles (weft tie treadle count)

• Special Properties (when applicable):

  • Huck Style (Type A, B, C, or D)

  • Has Weft Background

  • Tie-up Pattern Reverse

  • Pattern Warp Wrap

  • Pattern Step value

• Preview Image — A small visual showing what the template's weave pattern looks like

Apply Button

Generates the expanded draft from the selected template applied to your profile.

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How It Works

What You Need: A Profile Draft

A profile draft is a simplified block representation of your design. Each shaft represents a "block" and each treadle represents a block activation. For example, a 2-block profile draft has 2 shafts and 2 treadles, with a simple tie-up showing which blocks are active.

The profile defines where each block appears in the design — the template defines how each block is woven.

The Substitution Process

When you click Apply, the generator:

1. Reads your profile draft — Identifies the block layout from your threading, treadling, and tie-up

2. Reads the template — Loads the template's weave structure, including its threading pattern, treadling, and tie-up

3. Builds shaft and treadle maps — Determines how the template's shafts and treadles are distributed across your profile blocks:

   • Tie shafts/treadles are shared across all blocks (they provide the ground structure)

   • Pattern shafts/treadles are multiplied per block (each block gets its own set)

4. Expands the threading — Each profile thread is expanded into the template's threading pattern, mapped to the correct shaft group for that block

5. Builds the tie-up — The template's tie-up is expanded across all block combinations, with special handling for Huck variants, weft backgrounds, and other template-specific rules

6. Expands the treadling — Each profile pick is expanded into the template's treadling pattern, mapped to the correct treadle group

7. Creates the output — A new WIF file with the complete expanded structure

Template Types

Different template types have different substitution rules:

Huck — Lace-producing templates with tie shafts and pattern shafts. Four variants (A, B, C, D) control whether blocks produce lace openings, warp floats, weft floats, or opposite-parity lace.

Overshot — Traditional American block weave with pattern floats over a plain weave ground. Uses stepping patterns and block sequences.

Summer and Winter — Versatile block weave with tie-down shafts and independent pattern blocks. Produces reversible fabric.

Custom — User-defined templates that follow the general shaft/treadle mapping rules.

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The Template Editor

When adding or editing a template:

Name — A descriptive name for the template.

File Name — The WIF file containing the template's weave structure. Click Browse to select a file.

Type — The weave family (Huck, Overshot, Summer and Winter, Double Weave, Custom, etc.).

Template Shafts — Total shafts in the template pattern.

Block Treadles — Treadles per block in the pattern.

Warp Tie Count — Number of tie-down shaft rows.

Weft Tie Treadles — Number of tie treadles.

Pattern Warp Step — For overshot patterns, the step value for progressive shaft assignment.

Weft Background — The template has a separate background pattern for non-active blocks.

Tie-up Pattern Reverse — Inverts the block selection logic in the tie-up.

Pattern Warp Wrap — Wraps pattern shafts when they exceed the maximum, preventing shaft overflow.

Huck Style — Enables special Huck lace handling. Choose variant A, B, C, or D.

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How to Use It

1. Create a profile draft — Set up a simple block design:

   • Thread with shaft numbers representing blocks (shaft 1 = block A, shaft 2 = block B, etc.)

   • Treadle with treadle numbers representing block activations

   • Set up a tie-up showing which blocks are active for each treadle

2. Open Block Substitution from the Design tab

3. Browse the template library — Click templates to see their details and preview

4. Select a template that matches the weave you want

5. Click Apply

6. The generated draft opens as a preview — review the expanded threading, tie-up, and treadling

7. Save the generated draft if satisfied

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Step-by-Step Example: Huck Lace from a Profile

You have a 3-block profile draft for a lace scarf and want to apply a Huck lace template:

1. Your profile has 3 shafts (3 blocks), 3 treadles, and a simple tie-up

2. Open Block Substitution

3. Select a Huck template (e.g., "Huck Lace 8-Shaft, Type A")

4. The info panel shows: 8 shafts, 4 treadles per block, 2 tie shafts, Huck Style Type A

5. Click Apply

6. The generator creates a full draft with:

   • Threading: tie-down threads + pattern threads for each of the 3 blocks

   • Tie-up: Huck lace connections for all block combinations

   • Treadling: expanded treadle sequence

7. Review and save

Step-by-Step Example: Overshot from a Simple Profile

You have a 4-block profile and want traditional overshot:

1. Thread your profile: 4 shafts representing 4 blocks

2. Design a simple treadling sequence in the profile

3. Open Block Substitution, select an Overshot template

4. Apply — the generator expands each profile block into the overshot threading pattern with tabby ties and pattern treadles

5. The result is a complete overshot draft ready for the loom

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Tips

• Profile drafts are simple — Keep your profile draft minimal: one shaft per block, one treadle per block activation. The template handles all the complexity.

• Preview before saving — Generated drafts open as unsaved previews. Review the structure before committing.

• Try different templates — Apply different templates to the same profile to compare how the same block layout looks in Huck vs. Overshot vs. Summer and Winter.

• Huck variants matter — The four Huck types (A, B, C, D) produce very different fabrics from the same profile. Type A gives lace, Type B gives warp floats, Type C gives weft floats, Type D gives opposite-parity lace.

• Check shaft limits — Block substitution can produce drafts with many shafts (blocks × pattern shafts + tie shafts). Make sure the result fits your loom. The maximum is 128 shafts.

• Custom templates — You can create your own templates by designing a weave structure in a WIF file and adding it to the template library with the appropriate settings.

• Template files — Templates are stored as WIF files in the templates folder. The template library catalog is saved automatically.

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Quick Reference

Action	How
Open panel	Design tab > Block Substitution (toggle)
Select template	Click in template list
View details	See info panel below list
Apply template	Click Apply button
Add template	Click Add, configure in editor
Edit template	Select + click Edit
Delete template	Select + click Delete

Profile Draft	Block Substitution Output
1 shaft per block	Multiple shafts per block + tie shafts
1 treadle per activation	Multiple treadles per block + tie treadles
Simple tie-up	Full expanded tie-up with block interactions
N threads	N × template pattern width threads

Template Type	Characteristic
Huck	Lace with tie-down threads, 4 variants
Overshot	Pattern floats over plain weave ground
Summer and Winter	Reversible, independent blocks
Custom	User-defined substitution rules