CNC File Formats Explained
CNC file formats are the digital instructions that tell bridge saws, routers, and waterjets exactly where and how to cut, drill, and shape countertop slabs. The main formats used in stone fabrication are DXF for geometry transfer and G-code (or proprietary equivalents) for machine instructions. Understanding these formats helps you troubleshoot production issues and choose compatible equipment.
TL;DR
- DXF is the standard geometry format - it defines what to cut but not how to cut it
- G-code is the standard machine instruction format - it tells the CNC the exact movements and speeds
- Most stone CNC machines use proprietary post-processors that convert DXF geometry into machine-specific instructions
- File format mismatches between equipment cause delays, errors, and wasted material
- Knowing the difference between input formats (DXF) and output formats (G-code) helps you diagnose problems faster
- SlabWise handles format conversion between templating devices and CNC machines automatically
File Format Categories in Stone Fabrication
CNC file formats fall into three categories, each serving a different purpose:
Category 1: Geometry Formats (What to Cut)
These files describe the shape of the countertop - the perimeter, cutouts, drill points, and edge assignments - without specifying machine movements.
| Format | Full Name | Used For | Industry Adoption |
|---|---|---|---|
| DXF | Drawing Exchange Format | Template transfer | Nearly universal |
| DWG | Drawing (Autodesk) | CAD editing | Common in office |
| SVG | Scalable Vector Graphics | Web/display only | Rare in fabrication |
| STEP | Standard for Exchange of Product Data | 3D geometry | Growing for complex shapes |
| IGES | Initial Graphics Exchange | 3D surfaces | Declining, replaced by STEP |
DXF dominates. In U.S. countertop fabrication, over 90% of template-to-CNC transfers use DXF. The other formats appear in specialized situations (DWG for detailed CAD work, STEP for complex 3D shapes on 5-axis machines).
Category 2: Machine Instruction Formats (How to Cut)
These files contain the exact movements, speeds, and tool commands the CNC machine executes. They're generated from geometry files by post-processor software.
| Format | Full Name | Used By | Description |
|---|---|---|---|
| G-code | Geometric Code | Many CNC types | Industry-standard machine language |
| ISO code | ISO 6983 standard | Standardized CNC | Standardized version of G-code |
| NC | Numerical Control | Generic CNC | Often same as G-code with different extension |
| TAP | N/A | Older CNC | Legacy format, still used by some machines |
Category 3: Proprietary Formats (Vendor-Specific)
Many CNC manufacturers use proprietary formats that only their machines understand:
| Manufacturer | Proprietary Format | Based On | Notes |
|---|---|---|---|
| Park Industries | .park | Modified G-code | Includes material parameters |
| Intermac | .imac | ISO code variant | Includes tool change sequences |
| Breton | .breton | Modified NC | Includes water flow control |
| BACA Systems | .baca | Modified G-code | Includes saw parameters |
| GMM | .gmm | ISO code variant | Includes bridge movement sequences |
| Northwood | .nwd | Modified G-code | Includes vacuum table positions |
These proprietary formats usually start as standard G-code with manufacturer-specific extensions for their hardware features (vacuum tables, water flow, tool changers, bridge positioning).
How Files Flow Through a CNC Workflow
Understanding the file flow helps you identify where problems occur:
Field Template (Laser Templater)
|
v
DXF File (Geometry Only)
|
v
Shop Software (Add Edge Profiles, Seams, Nesting)
|
v
Processed DXF (Complete Fabrication Geometry)
|
v
CAM Software / Post-Processor
|
v
G-code or Proprietary Format (Machine Instructions)
|
v
CNC Machine (Executes the Program)
Where errors happen most:
- DXF to DXF (between systems): Layer naming, unit, and version incompatibilities
- DXF to G-code (post-processing): Wrong post-processor, incorrect tool parameters, wrong material settings
- G-code to machine: Communication errors, outdated firmware, incorrect machine setup
G-Code Basics for Stone Fabricators
You don't need to program G-code - your CAM software generates it automatically. But understanding the basics helps you read programs, diagnose errors, and communicate with your CNC technician.
Common G-Code Commands in Stone Cutting
| Command | Function | Example in Stone Fabrication |
|---|---|---|
| G00 | Rapid positioning (non-cutting move) | Moving to the start of the next cut |
| G01 | Linear cutting move | Straight-line perimeter cuts |
| G02 | Clockwise arc | Curved countertop sections |
| G03 | Counter-clockwise arc | Rounded inside corners |
| G28 | Return to home position | End of program, park the bridge |
| G40 | Cancel tool compensation | Reset after edge profiling |
| G41 | Left tool compensation | Cutting left of the programmed path |
| G42 | Right tool compensation | Cutting right of the programmed path |
Common M-Code Commands (Machine Functions)
| Command | Function | Example in Stone Fabrication |
|---|---|---|
| M00 | Program stop (wait for operator) | Pause for manual inspection |
| M03 | Spindle on (clockwise) | Start the blade or router bit |
| M05 | Spindle off | Stop the blade |
| M06 | Tool change | Switch from saw blade to edge router |
| M08 | Coolant/water on | Start water flow for wet cutting |
| M09 | Coolant/water off | Stop water flow |
| M30 | End of program | Return to start, reset |
Reading a Simple G-Code Program
Here's what a basic countertop perimeter cut looks like in G-code:
N10 G90 G21 (Absolute positioning, millimeters)
N20 M06 T01 (Select tool 1: saw blade)
N30 M03 S3000 (Start spindle at 3000 RPM)
N40 M08 (Water on)
N50 G00 X0 Y0 Z50 (Rapid move to start position, above slab)
N60 G01 Z-32 F500 (Plunge cut through 30mm slab, feed 500)
N70 G01 X2500 F1500 (Cut straight 2500mm along X axis)
N80 G01 Y650 (Cut 650mm along Y axis)
N90 G01 X0 (Cut back 2500mm)
N100 G01 Y0 (Cut back to start)
N110 G00 Z50 (Raise blade above slab)
N120 M09 (Water off)
N130 M05 (Spindle off)
N140 M30 (End program)
Even without programming knowledge, you can read this program and verify: the tool plunges 32mm (through a 30mm slab with 2mm clearance), cuts a rectangle roughly 2500mm x 650mm (about 98" x 25.5" - a standard kitchen counter), then retracts.
CAM Software and Post-Processors
What CAM Software Does
CAM (Computer-Aided Manufacturing) software converts DXF geometry into machine instructions. It decides:
- Tool paths: The exact route the cutting tool follows
- Cutting speeds: Feed rates appropriate for the material and tool
- Tool selection: Which tool to use for each operation (blade for cuts, router for edges, drill for holes)
- Cutting order: The sequence of operations to maintain slab stability
- Tool compensation: Offset the tool path to account for blade width (kerf)
Common CAM Software in Stone Fabrication
| Software | Common Pairings | Strengths |
|---|---|---|
| Alphacam | Many CNC brands | Widely used, flexible post-processors |
| SlabSmith | Layout + nesting | Vein matching and nesting optimization |
| GMM Techni Software | GMM machines | Integrated with GMM hardware |
| Park IntelliCAM | Park Industries | Optimized for Park machines |
| Intermac Master Software | Intermac machines | Native Intermac integration |
| Breton Smart Cut | Breton machines | Native Breton integration |
Post-Processors
A post-processor is a translation layer within CAM software that converts generic tool paths into the specific format your CNC machine expects. Think of it as the final translator.
Common post-processor issues:
- Using the wrong post-processor version for your machine firmware
- Post-processor doesn't account for a machine upgrade (new tool changer, additional axis)
- Feed rate limits in the post-processor don't match the actual machine capabilities
- Tool numbering in the post-processor doesn't match the physical tool positions
Best practice: Get your post-processor directly from your CNC manufacturer or CAM vendor. Test it with a simple program on scrap material before production use.
File Format Compatibility Matrix
This table shows which formats work between common equipment combinations:
| From / To | Alphacam | SlabSmith | Park IntelliCAM | Intermac Master | Breton Smart |
|---|---|---|---|---|---|
| Proliner DXF | Direct | Direct | Direct | Direct | Direct |
| LT-2D/3D DXF | Direct | Direct | Direct | Direct | Direct |
| Flexijet DXF | May need 2D conversion | May need 2D conversion | Direct | Direct | Direct |
| AutoCAD DWG | Convert to DXF first | Convert to DXF first | Convert to DXF first | Convert to DXF first | Convert to DXF first |
"Direct" means the file imports without conversion. "May need conversion" means some processing may be required.
Troubleshooting File Format Issues
Problem: CNC Won't Load the File
Possible causes:
- Wrong file format (sending DXF when machine expects G-code, or vice versa)
- Incompatible DXF version (file is DXF 2018, machine only reads R12-2004)
- Corrupt file (incomplete download, network error during transfer)
- File too large (complex geometry exceeds machine memory)
Fix: Verify the file format your CNC expects. Re-export in the correct version. Transfer the file again. For large files, simplify geometry (reduce arc segments, remove unnecessary layers).
Problem: CNC Runs But Cuts Wrong
Possible causes:
- Wrong post-processor selected in CAM software
- Tool compensation applied incorrectly (cutting on wrong side of line)
- Unit mismatch (inches vs. millimeters)
- Zero point set incorrectly on the machine
Fix: Verify the post-processor matches your machine model and firmware version. Check tool compensation direction. Verify units. Re-set the zero point.
Problem: Machine Stops Mid-Program
Possible causes:
- G-code contains commands the machine doesn't support
- Feed rate exceeds machine limits
- Tool change called for a tool that isn't loaded
- Emergency stop triggered by out-of-range movement
Fix: Review the G-code around the stop point. Check for unsupported commands. Verify feed rates are within machine specs. Verify all called tools are physically loaded.
How SlabWise Handles File Formats
SlabWise simplifies the file format challenge by managing the entire chain:
- Import: Accepts DXF from all major templating devices
- Process: Adds edge profiles, seams, and fabrication details from the job record
- Verify: AI checks dimensions and specifications before CNC programming
- Export: Generates DXF files formatted for your specific CNC machine and CAM software
- Track: Maintains a complete file history linked to each job
You configure your equipment profile once (which templaters and CNC machines you use), and SlabWise handles the format translation automatically for every job.
Frequently Asked Questions
What file format does my CNC machine use?
Most stone CNC machines accept DXF files as input and use internal CAM software to generate machine code. Check your machine documentation or ask the manufacturer. The most common input format is DXF R12 or DXF 2004.
What's the difference between DXF and G-code?
DXF describes what to cut (the shape). G-code describes how to cut it (the machine movements, speeds, and tool commands). Your CAM software or CNC controller converts DXF geometry into G-code instructions.
Do I need to learn G-code to run a CNC bridge saw?
No. Modern CNC software generates G-code automatically from DXF geometry. However, understanding basic G-code helps you troubleshoot when things go wrong - knowing what a G01 or M06 command does can help you diagnose errors without waiting for a technician.
Why does my CNC cut in the wrong place?
The most common causes are: wrong zero point on the machine, unit mismatch (file in mm, machine set for inches), incorrect tool compensation direction, or slab not positioned correctly on the bed. Check each one systematically.
Can I use the same DXF file on different CNC machines?
Usually, but not always. Different machines may expect different layer names, unit systems, or DXF versions. If you have multiple CNC machines from different manufacturers, you may need different export configurations for each machine. Middleware or integrated software like SlabWise handles this automatically.
What is a post-processor?
A post-processor is software that converts generic cutting paths into the specific format your CNC machine understands. It accounts for your machine's capabilities, tool positions, movement limits, and communication protocol. Using the wrong post-processor is a common cause of CNC errors.
How do I update my CNC's post-processor?
Contact your CNC manufacturer or CAM software vendor. Post-processor updates are typically provided when you upgrade machine firmware or add new capabilities (like a tool changer). Never modify a post-processor yourself unless you're trained to do so.
What format should I archive completed job files in?
Keep the processed DXF file (with all layers, edge profiles, and fabrication details) as your primary archive. This format is readable by any CAD software and preserves all the geometry data. Optionally keep the G-code file as well, but DXF is the more universal and long-lasting format.
Simplify Your CNC File Workflow
SlabWise handles file format conversion between your templating devices and CNC machines automatically. Upload a DXF from any major templater and export a CNC-ready file for any major machine - no manual format conversion needed.
Start Your 14-Day Free Trial - compatible with all major templaters and CNC equipment.
Sources
- Society of Manufacturing Engineers. "CNC Programming Standards for Stone Fabrication." SME Technical Paper, 2024.
- Autodesk. "DXF Reference Documentation." Autodesk Developer Network, 2024.
- Park Industries. "CNC File Format Requirements and Best Practices." Technical Documentation, 2024.
- Alphacam. "Post-Processor Configuration Guide for Stone Applications." Software Documentation, 2024.
- International Surface Fabricators Association. "CNC Technology Standards for Countertop Fabrication." ISFA Technical Guide, 2024.
- Stone World Magazine. "CNC Programming Trends in the Stone Industry." Stone World Annual Review, 2024.