Understanding CNC Machining Tolerances for Custom Parts

## Why Tolerances Matter Tighter tolerances = higher precision = higher cost. Specifying unnecessarily tight tolerances can double or triple your manufacturing cost without improving part performance. ## Standard Tolerance Grades ### ISO 2768 (General Tolerances) | Grade | Description | Typical Use | |-------|-------------|-------------| | f (fine) | ±0.05mm to ±0.2mm | Precision components | | m (medium) | ±0.1mm to ±0.5mm | General engineering | | c (coarse) | ±0.2mm to ±2mm | Rough parts, weldments | | v (very coarse) | ±0.5mm to ±4mm | Non-critical dimensions | ### Geometric Tolerances - **Flatness**: Surface deviation from ideal plane - **Parallelism**: Deviation between two parallel surfaces - **Perpendicularity**: 90° angle accuracy - **Runout**: Circular deviation during rotation - **Position**: Location accuracy of features ## Best Practices 1. Only tolerance critical functional dimensions 2. Use general tolerances for non-critical features 3. Consider the manufacturing process capabilities 4. Remember: tighter tolerances require more setups and inspection 5. Discuss tolerance requirements with your manufacturer early ## GRANGIN CNC Capabilities - **General Tolerance**: ISO 2768-m (medium) - **Achievable**: Up to ±0.01mm on critical features - **Materials**: Steel, stainless steel, aluminum, brass, engineering plastics - **Max Part Size**: 2000mm × 1000mm × 800mm Contact us with your drawings for a free manufacturability review and quotation.