For linear dimensions (lengths, widths, depths, steps, etc.), class applies.
The stands for Medium accuracy. This is the most common standard for general machining. It applies to linear dimensions (lengths, widths, heights) unless a specific tolerance is called out directly on the dimension. iso 2768-mh tolerance chart
The "m" (medium) class is the most common standard for general CNC machining . It provides acceptable variance for lengths, radii, and diameters based on the nominal size of the feature . Nominal Size Range (mm) Tolerance (± mm) for Class Over 3 to 6 Over 6 to 30 Over 30 to 120 Over 120 to 400 Over 400 to 1000 Over 1000 to 2000 ISO 2768-2: Geometrical Tolerances (Class h) For linear dimensions (lengths, widths, depths, steps, etc
| Nominal Dimension Range (mm) | Permissible Deviation for Class 'm' (mm) | | :--- | :--- | | 0.5 up to 3 | ± 0.1 | | >3 up to 6 | ± 0.1 | | >6 up to 30 | ± 0.2 | | >30 up to 120 | ± 0.3 | | >120 up to 400 | ± 0.5 | | >400 up to 1000 | ± 0.8 | | >1000 up to 2000 | ± 1.2 | | >2000 up to 4000 | ± 2.0 | It applies to linear dimensions (lengths, widths, heights)
If you’ve ever looked at a mechanical drawing and seen the note in the title block, you’ve likely wondered: What exactly does this allow? How much deviation is acceptable?