| Shorter Side Length (mm) | Class f (Fine) | Class m (Medium) | Class c (Coarse) | Class v (Very Coarse) | | :--- | :--- | :--- | :--- | :--- | | | ±1° | ±1° | ±1°30′ | ±3° | | 10 up to 50 | ±0°30′ | ±0°30′ | ±1° | ±2° | | 50 up to 120 | ±0°20′ | ±0°20′ | ±0°30′ | ±1° | | 120 up to 400 | ±0°10′ | ±0°10′ | ±0°15′ | ±0°30′ | | > 400 | ±0°5′ | ±0°5′ | ±0°10′ | ±0°20′ |
If a single specific feature requires a tighter tolerance (e.g., a press-fit bearing shaft that needs a ±0.01 mm window), the engineer simply overrides the general standard by typing that specific tolerance directly next to the dimension on the layout.
These tables set limits on the allowable (e.g., flatness) and orientation (e.g., perpendicularity) of a feature. general tolerance iso 2768-mk
By utilizing this dual-classification system, a single note in the drawing block eliminates hundreds of redundant tolerance callouts, drastically improving drawing readability. 2. Linear and Angular Tolerances (Class m)
The uppercase letter represents the tolerance class for general geometrical features, such as straightness, flatness, perpendicularity, and symmetry. ISO 2768-2 defines three classes: H – Tight K – Medium L – Loose | Shorter Side Length (mm) | Class f
ISO 2768-1 stands for the general tolerances for linear and angular dimensions without individual tolerance indications, ISO 2768-
For a shaft, this is how much it can deviate from a perfect straight line. For a flat surface, this is how much it can deviate from a perfect plane. For a flat surface, this is how much
To solve this problem, the International Organization for Standardization created . This standard establishes a system of general tolerances that simplifies technical drawings by covering dimensions without explicitly stated tolerances.
Even when ISO 2768 is invoked, some dimensions are typically excluded. General tolerances do apply to the following:
Using a standard "medium" tolerance helps avoid unnecessarily tight specifications that drive up manufacturing costs.