Iso 2768-mk [work] — General Tolerance

ISO 2768-mk is the "Goldilocks" of manufacturing tolerances—not too tight, not too loose. It ensures that parts are functional and interchangeable without unnecessary manufacturing expenses. When you see it on a drawing, you’re looking at a standard of and Medium Geometrical control .

Applies to flatness, straightness, perpendicularity, symmetry, and circular runout.

Engineers save time because they only need to calculate and write out tight tolerances for critical, high-precision features.

ISO 2768 Certification: Definitions, Industries, Processes - Xometry general tolerance iso 2768-mk

Or, for clarity referencing both parts separately:

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.

Geometrical tolerances control form, orientation, and run-out. The class enforces medium control over these geometric features. Straightness and Flatness For a flat surface, this is how much

For broken edges (external radii and chamfer heights), the medium class specifies: 3. Angular Dimensions Tolerances (ISO 2768-1, Class m)

The tables below outline the permissible deviations for linear and angular dimensions under the "m" (Medium) classification. All values are listed in millimeters (mm) unless otherwise specified. Linear Dimensions

The code is broken down into two distinct classes: For a flat surface

| Nominal Size Range (mm) | Class f (Fine) | Class m (Medium) | Class c (Coarse) | Class v (Very Coarse) | | :--- | :---: | :---: | :---: | :---: | | | ±0.20 | ±0.20 | ±0.40 | ±0.40 | | 3 up to 6 | ±0.50 | ±0.50 | ±1.00 | ±1.00 | | 6 | ±1.00 | ±1.00 | ±2.00 | ±2.00 |

Choosing the correct tolerance class is a critical design decision that directly impacts manufacturing cost and feasibility.