> For the complete documentation index, see [llms.txt](https://docs.tempoweave.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tempoweave.com/help-by-menu-tabs/design-menu/block-substitution.md).

# 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.

***

### Location

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

The Block Substitution panel opens as a dockable tool window.

***

### 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 and Winter 4-Block," "Deflected Double Weave")
* **Type** — Weave category (Huck, Overshot, Summer and Winter, Deflected Double, 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.

The built-in set includes **Deflected Double Weave** — a 2-shaft/2-treadle-per-block unit that weaves plain weave where same-system blocks meet and lets the deflected floats exchange elsewhere. In this template the two systems are the odd-numbered blocks (A, C, E…) and the even-numbered blocks (B, D, F…), so draw your profile with the two yarns on alternating block numbers. Templates added in new releases appear in your list automatically, alongside any templates you've added yourself.

#### Template Management

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

**Edit** — Modify the selected template's settings. The editor also offers two buttons next to the **File Name** field:

* **`…` Browse** — Pick a `.wif` from anywhere on disk; the file is copied into the templates folder for you.
* **`✎` Edit Template WIF** — Open the selected template's `.wif` in a new editor tab so you can change threading / treadling / tieup directly. Saving in that tab writes back to the templates folder, so the next Apply picks up the edits automatically. Especially useful on macOS where the `_blocktemplates` folder lives inside the invisible `~/Library` directory.

**Delete** — Remove the selected template from the library (your own templates only — see below).

**Reveal Folder** — Open the per-platform templates folder in Finder / Explorer / your file manager. Drop additional `.wif` files in directly if you prefer to work outside the dialog.

#### Bundled Templates Stay Current

The templates that ship with TempoWeave are kept up to date automatically: every release refreshes them, so fixes and improvements to the bundled set simply appear. To make that safe, bundled templates are read-only in place:

* **Editing a bundled template automatically works on a copy.** Change any setting, or open its WIF for editing, and TempoWeave creates "*Template Name* (copy)" and applies your changes there — the original stays pristine and keeps receiving updates.
* **Bundled templates can't be deleted** (the Delete button tells you so). Copies and templates you added yourself can be deleted freely.
* If a past version let you modify a bundled template directly, your modified file isn't lost on update — it's set aside in a `_replaced` folder inside the templates folder, and the refreshed original takes its place.

#### 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. A short prompt comes first:

* **Repeat Warp Units / Repeat Weft Units** — how many times each profile end's threading unit and each profile pick's treadling unit is laid down before moving on to the next. The default of 1 is the classic result. The repeat is per unit, in sequence, the way polychrome Summer and Winter needs it, not the whole draft repeated after itself. The ground cycle stays continuous across repeats.
* **Add tabby treadling** — shown for templates that weave with tabby. Leave it checked to have the tabby picks written into the treadling.
* **Block lengths** — shown for templates whose unit is a pure cycle, such as Deflected Double Weave (1, 2, 1, 2). Set **Threads per odd block**, **Threads per even block**, **Picks per odd block**, and **Picks per even block**. Odd blocks are profile blocks 1, 3, 5… and even blocks 2, 4, 6…; in deflected double weave those are the two layers, so a project that wants six ends of one yarn and seven of the other is two numbers here rather than a hand-edited template. Each layer's shaft alternation carries on from one of its blocks to the next: a seven-thread block that ends on shaft 1 makes the layer's next block start on shaft 2, so odd lengths come out with the parity a DDW threading needs. The defaults are the template's own lengths, which gives exactly the draft you got before.

***

### 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 profile can be either a **tie-up draft** or a **liftplan draft**:

* **Tie-up profiles** — Each pick presses a treadle, and the tie-up says which blocks that treadle activates. Picks that press more than one treadle activate all of their blocks at once.
* **Liftplan profiles** — Each shaft is a block, and each pick simply lifts the block(s) it activates. A pick lifting shafts 1 and 3 weaves pattern in blocks A and C together. Liftplan profiles produce a **liftplan result**: the generated draft comes out as a liftplan too, ready for dobby looms, with each pick lifting the combined shafts of its expanded structure.

#### The Substitution Process

When you click **Apply**, the generator:

1. **Reads your profile draft** — Identifies the block layout from your threading and treadling + tie-up (or liftplan)
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:

**Bronson / Bateman** — Spot-pattern weaves where a base of plain weave alternates with isolated pattern floats.

**Crackle** — A 4-shaft block weave with a broken-twill texture that gives the weave its name.

**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 / 3 Tie / 4 Tie / Double Two Tie** — Tie-unit weaves with independent pattern blocks. Produce reversible fabric; the number of tie shafts in the name corresponds to the per-block tie count.

**Diversified Plain** — A multi-block weave alternating fine and coarse threads to produce distinct color blocks against a plain-weave ground.

**Double Weave** — Two interleaved cloths joined at block boundaries.

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

***

### 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.

***

### 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
   * Or, in a liftplan draft, just lift each pick's block shaft(s) — no tie-up needed
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

***

### 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

***

### 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.

***

### Going Deeper: Authoring Templates

To **edit** the bundled templates, or **author** new ones for the Complex Weavers community (or your own block-substitution library), see the companion Block Substitution Authoring Guide. It covers:

* Where the templates live on each operating system
* The anatomy of a template WIF, including the `*WarpPattern` / `*TieShafts` section markers
* What each flag in the editor (Block Treadles, Warp Tie Count, Pattern Warp Step, Pattern Warp Wrap, Weft Background, Tie-up Pattern Reverse, Huck Style) actually does to the output
* Step-by-step walkthroughs for editing a bundled template and building a new one from scratch
* The **Edit Template WIF** (`✎`) button in the Edit Templates dialog, and how the automatic copy-on-edit of bundled templates interacts with authoring
* A troubleshooting playbook for the common authoring mistakes

***

### 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        |

{% embed url="<https://vimeo.com/1202475470>" %}
Creating a Simple Profile Draft
{% endembed %}

This is a short overview of Block Substitution:

{% embed url="<https://vimeo.com/1226352933?share=copy&fl=sv&fe=ci>" %}

For more information on Block Weaves and Block substitution, see this mini-course:&#x20;

[Working with Profile Drafts and Block Substitution](/tempoweave-course-library/working-with-profile-drafts-and-block-substitution/profile-drafts-and-block-substitution.md)