# CNC Fabrication for Architecture Computer Numerical Control (CNC) fabrication enables architects to translate complex digital geometries directly into physical components through automated subtractive manufacturing. CNC machines remove material from stock using precisely controlled cutting tools, allowing production of bespoke building components with high accuracy and repeatability at scales ranging from small-scale prototypes to full building elements. --- ## Table of Contents - [CNC Fundamentals](#cnc-fundamentals) - [Machine Types](#machine-types) - [Material Capabilities](#material-capabilities) - [File Preparation Workflow](#file-preparation-workflow) - [Tolerances and Precision](#tolerances-and-precision) - [Architectural Applications](#architectural-applications) - [Design for CNC Manufacturing](#design-for-cnc-manufacturing) - [See Also](#see-also) --- ## CNC Fundamentals | Term | Definition | |------|-----------| | **Subtractive Manufacturing** | Material removal from solid stock (opposite of additive/3D printing) | | **G-code** | Machine instruction language controlling tool movement | | **Toolpath** | Calculated route the cutting tool follows | | **Feed Rate** | Speed of tool movement through material (mm/min) | | **Spindle Speed** | Rotation speed of cutting tool (RPM) | | **DOC** | Depth of Cut — material removed per pass | | **Step-over** | Distance between adjacent toolpath lines | --- ## Machine Types | Machine | Axes | Typical Use | |---------|------|-------------| | **CNC Router** | 3-axis | Sheet cutting, panel milling, joinery | | **5-Axis CNC Mill** | 5-axis | Complex 3D forms, double-curved panels | | **CNC Lathe** | 2-axis rotary | Columns, balusters, turned elements | | **CNC Wire Cutter** | 2-4 axis | Foam molds, EPS formwork | | **CNC Plasma/Waterjet** | 2-3 axis | Metal plate cutting | | **CNC Tube Bender** | Multi-axis | Structural steel tubes, railings | ### Bed Sizes (Typical) | Machine Class | Bed Size | Application | |---------------|----------|-------------| | Desktop | 600 x 400 mm | Prototyping, models | | Workshop | 2440 x 1220 mm (8' x 4') | Standard sheet goods | | Industrial | 3000+ x 1500+ mm | Full-scale panels, timber beams | | Gantry | 10,000+ mm length | [[Mass Timber Construction]] elements, CLT | --- ## Material Capabilities | Material | Tool Type | Notes | |----------|-----------|-------| | **Timber/Plywood** | Carbide end mills, ball-nose | Most common architectural CNC material | | **MDF/Particle Board** | Carbide end mills | Dust extraction critical | | **Aluminium** | Carbide, coated end mills | Slower feed rates, coolant recommended | | **Steel** | HSS/Carbide with coolant | Limited to lighter gauges on routers | | **Stone/Marble** | Diamond-tipped tools | Requires specialized machines, water cooling | | **Foam (EPS/XPS)** | Hot wire or router | Formwork for concrete casting | | **Acrylic/Polycarbonate** | Single-flute cutters | Heat management critical to avoid melting | | **Composite Panels** | Diamond-tipped PCD tools | ACM, fibre cement panels | --- ## File Preparation Workflow 1. **3D Model** — Design in Rhino, Revit, or other CAD software 2. **CAM Software** — Import geometry into CAM (RhinoCAM, Fusion 360, Mastercam) 3. **Toolpath Generation** — Define cutting operations, tool selection, speeds/feeds 4. **Simulation** — Virtual machining to verify toolpaths and detect collisions 5. **Post-Processing** — Convert toolpaths to machine-specific G-code 6. **Machine Setup** — Mount material, set origin, load tools 7. **Cutting** — Execute programme with operator monitoring 8. **Finishing** — Sanding, coating, assembly ### Common CAM Software | Software | Strengths | |----------|-----------| | **RhinoCAM** | Direct integration with Rhino/Grasshopper | | **Fusion 360** | Free for startups, combined CAD/CAM | | **Mastercam** | Industry standard, advanced toolpath strategies | | **KUKA|prc** | Robotic CNC control via Grasshopper | --- ## Tolerances and Precision | Factor | Typical Range | |--------|---------------| | **Machine Accuracy** | ±0.05–0.1 mm (industrial), ±0.2 mm (workshop) | | **Repeatability** | ±0.025 mm (industrial) | | **Surface Finish** | Dependent on step-over, tool type, material | | **Joint Tolerances** | 0.1–0.5 mm gaps for timber joinery | | **Thermal Expansion** | Must account for metal parts in precision assemblies | --- ## Architectural Applications | Application | Description | |-------------|-------------| | **Timber Joinery** | CNC-cut mortise-tenon, dovetail, finger joints for [[Mass Timber Construction]] | | **Facade Panels** | Custom-shaped cladding panels with complex perforations | | **Formwork** | Milled EPS/foam for complex concrete forms | | **Furniture/Fitout** | Bespoke joinery, reception desks, shelving systems | | **Acoustic Panels** | Profiled surfaces for sound diffusion | | **Stair Components** | Stringers, treads with complex geometry | | **Signage/Wayfinding** | Precision-cut letters and directional elements | | **Structural Nodes** | Complex steel connections milled from solid billets | --- ## Design for CNC Manufacturing | Principle | Guideline | |-----------|-----------| | **Minimum Internal Radius** | Equal to tool radius (typically 3–6 mm for routers) | | **Nesting** | Arrange parts to minimize material waste | | **Tab/Bridge Design** | Small connecting tabs prevent parts from moving during cutting | | **Grain Direction** | Consider for timber and plywood parts | | **Tool Access** | Ensure cutting tool can reach all features (no undercuts on 3-axis) | | **Assembly Sequence** | Design joints for logical assembly order | | **Labelling** | Engrave part numbers/orientation marks during machining | --- ## See Also - [[Robotic Fabrication]] - [[3D Printing in Architecture]] - [[Digital to Physical Workflow]] - [[Mass Timber Construction]] - [[Parametric Design Fundamentals]] - [[Laser Cutting and Prototyping]] --- #cnc #digital-fabrication #manufacturing #timber #digital-practice