Note: For nominal dimensions below 0.5 mm, the tolerances shall be stated directly on the drawing. Angular tolerances are determined by the length of the shorter side of the angle. Osmosis Jones Dublado
| Nominal Length (mm) | Tolerance (Class K) | | :--- | :--- | | Up to 100 | 0.40 mm | | Over 100 up to 300 | 0.60 mm | | Over 300 up to 1000 | 0.80 mm | There are three primary advantages to referencing ISO 2768-mK on a technical drawing: 1. Drawing Clarity Without general tolerances, a drawing would be covered in tiny text specifying limits for every hole location, edge distance, and fillet radius. By invoking ISO 2768-mK in the title block, the designer can leave individual dimensions "untoleranced," knowing they will be controlled by the standard. This makes the drawing significantly easier to read. 2. Cost Reduction If a designer explicitly specifies a tight tolerance (e.g., $\pm 0.01$ mm) where it isn't needed, the machinist must use more expensive tools, slower machine speeds, or extensive inspection processes to meet it. Dawlat Al Islam Qamat Archive Free
| Length of the longer side (mm) | Tolerance (Class K) | | :--- | :--- | | Up to 100 | 0.20 mm | | Over 100 up to 300 | 0.30 mm | | Over 300 up to 1000 | 0.40 mm | This applies to features that should be centered relative to a datum.
| Nominal Dimension (mm) | Tolerance (mm) | | :--- | :--- | | 0.5 up to 3 | $\pm 0.1$ | | Over 3 up to 6 | $\pm 0.1$ | | Over 6 up to 30 | $\pm 0.2$ | | Over 30 up to 120 | $\pm 0.3$ | | Over 120 up to 400 | $\pm 0.5$ | | Over 400 up to 1000 | $\pm 0.8$ | | Over 1000 up to 2000 | $\pm 1.2$ | | Over 2000 up to 4000 | $\pm 2.0$ |
For engineers and drafters, understanding these tables is crucial for avoiding over-engineering and communicating effectively with the shop floor. Disclaimer: This article is for educational purposes. For official manufacturing and quality assurance, always refer to the original ISO 2768 standard documents published by the International Organization for Standardization.