Mastering accuracy: Basic skills for CNC stone carving
Stone engraving using CNC technology has revolutionized the monumental, architectural and art industries. Combining ancient craftsmanship with modern precision, five-axis CNC machining can perform complex designs on granite, marble, quartz, etc. At Greatlight, our advanced five-axis system and deep material expertise enable artisans and manufacturers to push creative boundaries. Here we share actionable tips to enhance your stone engraving project.
Design optimization
- Vectorized artwork:
Use software like Adobe Illustrator to convert raster images (JPEG/PNG) to vector paths (SVG, DXF). Vectors ensure no pixelated smooth, scalable outline.
- Depth gradient:
Use 3D modeling software (e.g. Fusion 360, ArtCam) to simulate depth changes. For shallow engraving (e.g., memorial patches), keep the depth below 3 mm to avoid fragility of stone; deep relief may require a step-by-step tool path.
- Prevent cutting:
The five-axis machine excels in multi-angle machining, but avoids extreme undercuts. Optimize tool routes to maintain a clearance angle of 10–15° to extend tool life.
Material selection and preparation
- The hardness of the stone is very important:
- Soft stones (Marble, Limestone): Ideal details. Use a diamond coating tool of 8,000–10,000 rpm.
- Hard stone (Gramite, basalt): A robust tool is required. Carbide end mill handle abrasive surface with diamond gravel.
- Surface calibration:
Fix the flat plate with epoxy putty on the pan to eliminate the gaps. Mill the stone surface flat (operation-oriented) before engraving to ensure consistent depth.
Tools and strategies
- Diamonds and carbides:
Diamond tip tools last 10 times longer, but they are more costly. Carbides are economical for prototyping of softer materials.
- Tool geometry:
- Spherical end mill: Used for 3D contours and organic shapes (such as sculptures).
- V position (30°–90°): Generate clear fonts and sharp edges.
- Engraving tools and crushers: Prevent dust from accumulation in deep cavity.
- No coolant operation:
Stone carving creates dust, not heat. Use an integrated vacuum system or mist collector to protect the machinery. Avoid using water-based coolants – they can stain porous stones.
Machine parameters
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Speed and feed: Stone type RPM Feed rate (mm/min) Depth/pass marble 9,000–12,000 700–1,000 1-2 mm granite 7,000–9,000 400–600 0.5–1 mm - Climbing up milling: Always prioritize climbing milling (moving with material) to clean edges and reduce debris.
- Stepover Optimization: Keep the tool diameter of step ≤8% to avoid visible ridges.
Worker Solutions
- Vacuum meter: Effective for tablets. Ensure that surface porosity does not damage suction.
- Custom fixtures: For irregular shapes (e.g., river rock), cast silicone to fix the parts.
- Weighted fixture: Vertical setting is performed using a non-fixed nylon tape with lead weight.
Reduce dust
Stone dust can accelerate machine wear and bring health risks. Implementation:
- HEPA filtered vacuum system with hood close to the cutting area.
- Air scrubber for enclosed CNC cabinet.
- Operator PPE: N95 mask and goggles.
Post-processing and completion
- clean: Blow compressed air into the carved cavity; avoid water on unsealed stones.
- Highlight: Filled with metallic pigment (bronze/gold) to create contrast.
- seal: Apply penetrating sealant (for example, silicone-based) to an UV-resistant finish.
- Hand polishing: For advanced projects, with a gain edge with diamond abrasive pad (3,000+ grit).
Solve FAQs
- edge: Reduce feed rate by 20% or use smaller tools.
- Tool breaks: Check material vibration; make sure the workpiece is completely fixed.
- Surface burning: Lower rpm on soft stones.
Why five-axis CNC is a game-changer
Five-axis machines (such as the state-of-the-art systems of Greatlight) are enabled:
- Complex 3D geometry in a single setup (e.g., curved relief).
- Continuous tool participation at the best angle, double the tool life.
- The cycle speed is 25% faster than the three-axis alternative.
in conclusion
CNC stone engraving combines artistic vision with engineering precision. From optimizing tool paths to fighting dust, mastering these techniques ensures perfect results. As a leader in five-axis CNC machining, Great Provides unrivalled expertise in stone, metal and composite manufacturing. Equipped with cutting-edge technology and a commitment to one-stop solutions (from prototyping to post-processing), we give customers confidence to create. Ready to turn your idea into a stone? Today, customize precision stone prints with Greatlime.
FAQ
Q1: Can CNC carve natural stones with cracks or cracks?
Answer: Not recommended. Internal defects can cause breakage during processing. Check for stones with UV light to detect hidden weaknesses.
Q2: How to prevent tool deflection in deep engraving?
A: Use fixed-length tools (minimum overhang) to reduce step depth and use trochoidal milling paths for chip evacuation.
Q3: Is wet processing feasible for stones?
A: It is rarely necessary. The wet system risks penetration and damage porous stones. Dry processing with dust extraction is safer.
Q4: Which file format is most suitable for CNC stone engraving?
A: Vector path (DXF), G code generated from CAM software or 3D model (STL, step).
Q5: How durable is CNC prints outdoors?
A: Deep prints (≥2mm) that last for decades. Sealed with UV-resistant coating every year.
Question 6: Can you engrave polished stone?
A: Yes, but masking the surface with vinyl before processing can prevent scratches. If necessary, the area after exposure is exposed.
Q7: What is the maximum engraving size?
A: Greglight’s five-axis machine has a handle of up to 4m x 2m. Custom sizes are available upon request.
Are there any more questions? Please contact our CNC stone experts for expert guidance!
