Iso 2768-mh Tolerance Chart Hot! ✭ [ VERIFIED ]

| Type | Condition | Tolerance | | :--- | :--- | :--- | | Linear (0.5-6mm) | Size | ±0.1mm | | Linear (6-30mm) | Size | ±0.2mm | | Linear (30-120mm) | Size | ±0.3mm | | Linear (120-400mm) | Size | ±0.5mm | | Flatness | Form | 0.2mm per 100mm | | Straightness | Form | 0.2mm per 100mm | | Perpendicularity | Orientation | 0.3mm per 100mm | | Symmetry | Location | 0.5mm | | Circular Runout | Runout | 0.2mm | | Angle (<10mm leg) | Angle | ±1° | The ISO 2768-mh tolerance chart is the silent workhorse of modern mechanical drawings. By adopting "m" for linear and "H" for geometric tolerances, you strike an optimal balance between manufacturing cost and functional reliability.

"The 'H' means the same as the 'm'." Reality: No. 'H' is specifically from ISO 2768-2. It defines geometry, not size. A part can be the wrong size (within 'm') but perfectly flat (within 'H'). Creating Your Own ISO 2768-mh Reference Card For your workshop wall or CAD template, condense the ISO 2768-mh tolerance chart into this quick-reference table:

"If I write ISO 2768-mh, I never have to tolerance diameters." Reality: Diameters (like a Ø10mm hole) follow the SAME linear chart. A Ø10mm hole could be Ø10.2mm. That is an H11 tolerance loose fit. For a running fit, you still need an explicit H7 or G6. iso 2768-mh tolerance chart

'f' is too expensive for base material. 'c' is too loose for mating holes. 'mH' balances cost and functionality for 80% of mechanical parts. When NOT to Use ISO 2768-mh The existence of this chart does not mean you should never add explicit tolerances.

| Nominal Angle Range | Tolerance Class 'm' | | :--- | :--- | | Up to 10mm length of shorter side | ±1° | | >10mm up to 50mm | ±0°30' (30 arc minutes) | | >50mm up to 120mm | ±0°20' (20 arc minutes) | | >120mm up to 400mm | ±0°10' (10 arc minutes) | | >400mm | ±0°5' (5 arc minutes) | | Type | Condition | Tolerance | |

Among the four tolerance classes (f – fine, m – medium, c – coarse, v – very coarse), one stands out as the undisputed king of job shops, prototype development, and general machinery: .

Angular tolerances for untoleranced dimensions are not absolute degrees. They depend on the length of the legs. A short 5mm chamfer at 45° can deviate by 1°, while a long 200mm angled brace can only deviate by 0°5'. The 'H' Grade: Geometrical Tolerances (ISO 2768-2) The 'H' in ISO 2768-mh is where many engineers make mistakes. You cannot ignore geometry. For features that are not explicitly toleranced (e.g., a flat surface without a flatness callout), ISO 2768-2 applies. 'H' is specifically from ISO 2768-2

The 'H' grade corresponds to the "Medium" geometric class. Here is the for geometry: Table 2: ISO 2768-2 'H' Grade (Medium) Tolerances | Tolerance Class | Straightness & Flatness (mm) | Perpendicularity (mm) | Symmetry (mm) | Circular Runout (mm) | | :--- | :--- | :--- | :--- | :--- | | H (Medium) | 0.2 per 100mm length | 0.3 per 100mm length | 0.5 | 0.2 |