| Parameter | Value | |------------------------|----------------------| | Linear tolerance class | m (medium) | | Geometric tolerance class | H (precision) | | Typical application | General machining, turned/milled parts without individual tolerances | | Standard compliance | ISO 2768-1:1989, ISO 2768-2:1989 |
For example, a highly precise aerospace part might require , while a rough welded construction frame might only need ISO 2768-cL . If you(CNC machining, injection molding, sheet metal, etc.) What is the material of your part? Are you experiencing any specific fitment issues ? Share public link
"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.
If a specific feature requires a tighter tolerance than what the chart offers (for example, a bearing press-fit), you must explicitly write that custom tolerance next to that specific dimension on the drawing. The custom instruction will always override the general ISO 2768 chart. If youg., CNC milling, injection molding, sheet metal)? What are you working with? What is the intended function of the part? Share public link iso 2768-mh tolerance chart
Pitfalls:
This section compiles the key tolerance tables. Please note that all tolerance charts below are based on ISO 2768-1:1989.
Many engineers misread the chart because they forget the scaling rule for geometric tolerances. Let’s walk through three real-world scenarios. Share public link "If I write ISO 2768-mh,
| Nominal Length Range of the Shorter Leg (mm) | Permissible Deviation for Class 'm' | | :--- | :--- | | up to 10 | ± 1° | | >10 up to 50 | ± 0° 30' | | >50 up to 120 | ± 0° 20' | | >120 up to 400 | ± 0° 10' | | >400 | ± 0° 5' |
| Nominal Length Range in mm (approx.) | Tolerance Class "m" (± mm) | | :--- | :--- | | 0.5 up to 3 | ±0.1 | | over 3 up to 6 | ±0.1 | | over 6 up to 30 | ±0.2 | | over 30 up to 120 | ±0.3 | | over 120 up to 400 | ±0.5 | | over 400 up to 1000 | ±0.8 | | over 1000 up to 2000 | ±1.2 | | over 2000 up to 4000 | ±2.0 | | For nominal sizes below 0.5 mm, the deviations shall be indicated adjacent to the relevant nominal size(s). |
Geometrical tolerances restrict the form variation of a surface or line over its total length. Nominal Length Range (mm) General Tolerance (Class H) Over 10 to 30 Over 30 to 100 Over 100 to 300 Over 300 to 1000 Over 1000 to 3000 5. Perpendicularity (ISO 2768-2, Class H) For a running fit, you still need an explicit H7 or G6
The following tables show the permissible deviations for dimensions when "ISO 2768-mH" is referenced on a drawing. Table A: Linear Dimensions (ISO 2768-1 Medium - 'm')
Are there any that require tighter tolerances? Share public link
ISO 2768-mh tolerance chart is a standardized system used in mechanical engineering to simplify technical drawings by defining general tolerances for linear and geometrical dimensions without specific indications. The designation "mH" refers to a combination of two specific precision classes: (Medium) for linear and angular dimensions and for geometrical tolerances (form and position). Overview of ISO 2768
This chart applies to standard linear dimensions, such as lengths, widths, heights, steps, and diameters. Nominal Size Range (mm) Tolerance Value (Class m) over 3 to 6 over 6 to 30 over 30 to 120 over 120 to 400 over 400 to 1000 over 1000 to 2000 over 2000 to 4000 2. Broken Edges (External Radii and Chamfers)