In the world of mechanical engineering and CNC machining, precision is paramount. However, not every dimension on a technical drawing requires a tight, specific tolerance. Over-dimensioning a part can lead to skyrocketing production costs and unnecessary inspection time. This is where ISO 2768 becomes the silent hero of the workshop.
| Tolerance Class | Tolerance for nominal angle lengths (up to 10mm) | >10 up to 50mm | >50 up to 120mm | >120 up to 400mm | | :--- | :--- | :--- | :--- | :--- | | f (Fine) | ±1° | ±0°30' | ±0°20' | ±0°10' | | m (Medium) | ±1° | ±0°30' | ±0°20' | ±0°10' | | c (Coarse) | ±1°30' | ±1° | ±0°30' | ±0°15' | | v (Very Coarse) | ±3° | ±2° | ±1° | ±0°30' | The "Exclusive" part most PDFs lack is the geometrical section. If you write ISO 2768-m without a -2 , you only get linear tolerances. To get geometry, you need to specify the tolerance class for form and position. iso 2768 general tolerances pdf exclusive
For a 100mm tall feature, Grade H = 0.1mm deviation, Grade K = 0.2mm, Grade L = 0.4mm. In the world of mechanical engineering and CNC
Always verify your tolerance class with your manufacturing partner. If they are a high-volume stamping house, they may prefer "c" (Coarse). If they are a precision tool & die shop, "f" (Fine) is automatic. When in doubt, default to Class m for 90% of mechanical parts. Looking for the official standard? Purchase the original PDF from the ISO store or your local standards body (ANSI, BSI, DIN) to ensure you have the legally binding document. Use this guide for daily reference. This is where ISO 2768 becomes the silent