BTL Basics

Introduction to BTL: Rawparts, Nesting, and Process Ordering

Core Concepts

BTL (Building Transfer Language) is a format designed specifically for timber manufacturing. Unlike general CAD formats, it combines three key aspects:

1. Raw material definition

2. Component nesting

3. Manufacturing process ordering

1. Rawparts: The Starting Material

A rawpart in BTL represents your blank piece of timber material, such as:

• CLT panels

• Glulam beams

• Solid timber sections

Each rawpart has:

• Dimensions (length, width, height)

• Material properties

• Coordinate system

• Grain direction (optional)

Example:

[RAWPART]
LENGTH: 4000    # 4 meter length
WIDTH: 200      # 200mm width
HEIGHT: 100     # 100mm height
MATERIAL: "GL24h"

2. Nesting: Parts on Rawparts

BTL allows multiple finished parts to be nested onto a single rawpart:

• Each part has a unique ID (UID)

• Parts are positioned using transformation matrices

• Multiple parts can share one rawpart

• Nesting optimizes material usage

Example structure:

Rawpart (4m Glulam beam)
├── Part A: Rafter (1.2m)
│   └── Position: (0,0,0)
├── Part B: Rafter (1.2m)
│   └── Position: (1500,0,0)
└── Part C: Beam End (0.8m)
    └── Position: (3000,0,0)

3. Process Ordering: Manufacturing Optimization

BTL uses a sophisticated process ordering system that prioritizes manufacturing efficiency over component completion:

Priority Mechanisms:

1. Explicit Priority Values

PRIORITY: Integer   # Higher number = higher priority

1. Process Groups

• Groups 1,2: Separating processes (cuts)

• Groups 3,4: In-between processes (drilling, routing)

• Group 0: Universal processes

1. Tool-based Optimization

• Processes using the same tool are grouped

• Minimizes tool changes

• Optimizes machine movements

Example Process Flow:

Rawpart with 3 parts needing:
Part A: Cut, Drill(8mm), Slot
Part B: Cut, Drill(8mm)
Part C: Cut, Slot

Optimized Process Order:
1. All Cuts (same saw)
2. All 8mm Drilling (same drill bit)
3. All Slots (same router bit)

Real-World Example

Consider manufacturing roof rafters:

[RAWPART]
TYPE: GLULAM
LENGTH: 6000

  [PART] "Rafter 1"
  - Cut to 2000mm
  - Bird's mouth joint
  - 8mm holes for fixings

  [PART] "Rafter 2"
  - Cut to 2000mm
  - Bird's mouth joint
  - 8mm holes for fixings

Process Order:
1. Cut both rafters to length (same saw)
2. Cut both bird's mouth joints (same tooling)
3. Drill all 8mm holes (same drill bit)

This ordering:

• Minimizes tool changes

• Optimizes machine movements

• Reduces manufacturing time

• Improves efficiency

Key Differences from Traditional CAM

1. Component-Centric vs Process-Centric

• Traditional CAM: Complete one component before starting next

• BTL: Optimize across all components for efficiency

1. Material Usage

• Traditional CAM: Often one part per raw material

• BTL: Multiple parts nested on one rawpart

1. Process Organization

• Traditional CAM: Sequential by component

• BTL: Organized by tool and process type

Comparison with STEP and IFC

STEP (Standard for Exchange of Product Data)

1. Purpose & Scope

• General-purpose CAD/CAM exchange format

• Focuses on precise geometry and tolerances

• Handles assembly relationships

• Used across many industries (not timber-specific)

1. Key Differences from BTL

• More complex and verbose

• No timber-specific features

• Lacks optimization for wood manufacturing

• More detailed tolerance specifications

• No built-in nesting capabilities

• Process ordering is not inherent

1. When to Use STEP

• Exchanging general CAD data

• Need for detailed tolerancing

• Working with non-timber materials

• Complex geometric definitions

IFC (Industry Foundation Classes)

1. Purpose & Scope

• Building Information Modeling (BIM) format

• Focuses on building elements and relationships

• Contains project and construction information

• Used for full building documentation

1. Key Differences from BTL

• Building-level focus vs manufacturing focus

• No manufacturing process information

• Different type of nesting (spatial vs manufacturing)

• Contains non-geometric information (cost, scheduling)

• No machine processing instructions

• No material optimization features

1. When to Use IFC

• Building-level coordination

• Design documentation

• Project management

• Multi-discipline coordination

Format Selection Guide

Use BTL when:

• Manufacturing timber components

• Need CNC machine instructions

• Optimizing material usage

• Timber-specific processing

Use STEP when:

• Exchanging general CAD geometry

• Need precise tolerancing

• Working with multiple CAD systems

• Non-timber manufacturing

Use IFC when:

• Building-level coordination

• Full project documentation

• Multi-discipline collaboration

• Need building context

Benefits

1. Manufacturing Efficiency

• Reduced tool changes

• Optimized machine movements

• Better material utilization

1. Flexibility

• Can handle complex prefabrication

• Supports various machine types

• Adaptable to different manufacturing setups

1. Quality Control

• Process priority control

• Quality parameters per operation

• Manual intervention points when needed

BTL Processes Reference Table

Process Key Format

• First digit: Group (0,1,2,3,4)

  • 0: General/Universal

  • 1,2: Separating processes

  • 3,4: Processes lying between

Cutting and Basic Processes

Process Name	Process Key	Description	Key Parameters
Cut	1/2-010-X	Basic cut operation	P01: Distance from start, P06: Inclination, P07: Angle to reference
Longitudinal Cut	0/3/4-010-X	Cut along length	P01: Distance, P02: Depth, P07: Inclination
Double Cut	1/2-011-X	Two cuts meeting at point	P01: Distance, P06/P07: Cut angles
Ridge/Valley Cut	0-012-X	Roof ridge cuts	P07/P09: Face inclinations, P11: Depth
Saw Cut	0/3/4-013-X	Basic saw operation	P01: Distance, P06: Inclination, P11: Depth

Joints and Connections

Process Name	Process Key	Description	Key Parameters
Slot	3/4-016-X	Creates slot/groove	P11: Length, P12: Thickness, P13/P14: Displacement
Front Slot	3/4-017-X	Front-facing slot	P11: Width, P12: Length, P13: Depth
Birds Mouth	3/4-020-X	Roof framing joint	P07/P08: Angles, P11: Depth
Lap Joint	3/4-030-X	Overlapping joint	P11: Length, P12: Depth, P13: Angle
Block House Half Lap	4-037-X	Log construction joint	P11-P15: Lap dimensions
Dovetail	1/2/3/4-138-X	Traditional woodworking joint	P11: Length, P12: Depth
Tyrolean Dovetail	1/2/3/4-136-X	Regional dovetail variant	P11: Length, P14/P15: Dimensions

Drilling and Mortising

Process Name	Process Key	Description	Key Parameters
Drilling	3/4-040-X	Creates holes	P11: Diameter, P12: Depth
Mortise	3/4-050-X	Mortise for tenon	P11: Width, P13: Depth
Mortise Front	3/4-051-X	Front-facing mortise	P11: Width, P12: Depth
House Mortise	3/4-053-X	Special housing joint	Based on mortise parameters

Surface Operations

Process Name	Process Key	Description	Key Parameters
Planing	3/4-090-X	Surface smoothing	P11: Depth, P12: Length
Profile Front	3/4-100-X	Front profiling	P11/P12: Profile dimensions
Profile Head	3/4-106-X	End profiling	Multiple profile parameters
Chamfer	3/4-036-X	Edge beveling	P11: Depth, P12: Length

Specialized Operations

Process Name	Process Key	Description	Key Parameters
Marking/Labeling	3/4-060-X	Text/marks on timber	P15: Text string
Text	4-061-X	Text application	P13: Height, P15: Text string
Free Contour	0/3/4-250-X	Custom shape cutting	Multiple contour points
Sphere	3/4-107-X	Spherical cut	P11: Radius, P12/P13: Offsets
Variant	0/1/2/3/4-900-X	Custom processing	User-defined parameters

Special Joint Types

Process Name	Process Key	Description	Key Parameters
Step Joint	1/2-080-X	Stepped connection	P11: Depth, P14/P15: Dimensions
Simple Scarf	1/2-070-X	Basic scarf joint	P11/P12: Depths, P13: Length
Scarf Joint	1/2-071-X	Complex scarf joint	P11: Depth, P13: Length

Notes:

• All dimensions are in millimeters (mm)

• All angles are in degrees (°)

• X in process keys represents sequential numbering

• Most processes support transformation parameters for positioning

• Many processes include optional parameters for fine-tuning