These values apply per 100 mm of length. For longer lengths, the tolerance is prorated but limited by the maximum deviation.
– Same values as perpendicularity. Circular runout – 0.2 mm (class K). Total runout – Not defined; must be specified individually. Example: A 200 mm long machined surface without a flatness callout → allowed flatness deviation = 0.3 mm. 3.3 "E" – External Radii & Chamfer Heights (ISO 2768-1 Annex A) The "E" instructs that tolerances for external radii and chamfer heights follow the same "M" class limits as linear dimensions, but applied to the radius or chamfer size.
| Tolerance Class | Straightness & Flatness (mm per 100 mm) | Perpendicularity & Symmetry (mm per 100 mm) | Runout (mm) | |----------------|------------------------------------------|----------------------------------------------|--------------| | | 0.2 | 0.5 | 0.2 |
GENERAL TOLERANCES: ISO 2768-MK-E Alternatively:
1. Introduction ISO 2768-MK-E is a combined shorthand notation used on engineering drawings and technical documents. It references three parts of the ISO 2768 standard, which specifies default tolerances for linear dimensions, angular dimensions, geometrical features (form, orientation, location, and runout), and the indication of "E" for general external radius and chamfer dimensions.
