General Tolerances for Broken edges (external radii and chamfer)
General tolerances for broken edges (external radii and chamfer) are specified in ISO 2768-1:1989 and are used when no specific tolerance is given for a chamfer's length or angle or external radii in a drawing. Broken edges are often used to remove sharp edges, facilitate assembly of parts, and improve safety, so they usually require less precision than critical dimensions.
The tolerance classes (f, m, c, v) define how much the chamfer's dimensions may deviate from the nominal value. The smaller the broken edges, the tighter the tolerance; for larger broken edges, greater variation is acceptable.
This ensures that broken edges fulfill their intended purpose without requiring unnecessarily precise machining during manufacturing.
General Tolerance Table for Broken Edges (external radii and chamfer)
| Tolerance Class | Permissible Deviations in Nominal Size Range | ||||
| Symbol | Description | > | 0.5 | 3 | 6 |
| ≤ | 3 | 6 | |||
| f | fine | 0.2 | 0.5 | 1 | |
| m | medium | 0.2 | 0.5 | 1 | |
| c | coarse | 0.4 | 1 | 2 | |
| v | very coarse | 0.4 | 1 | 2 | |
The values in the table are given in millimeters (mm)
