General Tolerances for Perpendicularity
Perpendicularity is included in the general tolerances of standard ISO 2768-2:1989. It specifies how much two surfaces, edges, or axes are allowed to deviate from a perfect 90° angle when no separate tolerance has been specified.
General perpendicularity tolerances ensure that parts fit together without significant misalignment, while also avoiding unnecessarily strict manufacturing requirements. This is important, for example, when an edge meets another surface, a bearing seat meets a shaft, or mounting holes need to be drilled in line.
In a drawing, perpendicularity is not given a separate notation if general tolerances are used. It’s sufficient to indicate ISO 2768-mK on the drawing, in which case the permissible deviations specified by the standard, including perpendicularity, apply.
General Tolerance Table for Perpendicularity
| Tolerance Class | Straightness and Flatness Tolerances by Nominal Length Range | ||||
| Symbol | > | 100 | 300 | 1000 | |
| ≤ | 100 | 300 | 1000 | 3000 | |
| H | 0.2 | 0.3 | 0.4 | 0.5 | |
| K | 0.4 | 0.6 | 0.8 | 1 | |
| L | 0.6 | 1 | 1.5 | 2 | |
The values in the table are given in millimeters (mm)
