The Zeiss ISO 2768-2 PDF shows that these tolerances depend on the length of the feature being measured:
: Ensure the document contains both Part 1 (linear/angular) and Part 2 (geometrical) data.
To properly apply these general tolerances, a clear indication must be included in or near the drawing's title block. The format combines the lowercase letter from Part 1 and the uppercase letter from Part 2. ISO 2768-mK This single callout instructs the manufacturer to apply:
The default standard for structural engineering, automotive components, and standard machine parts. Highly achievable with standard milling, turning, and sheet metal fabrication.
Therefore, the manufactured part can legally measure anywhere from . If that same Iso 2768 General Tolerances Pdf
ISO 2768 is an international standard that defines general geometric and linear tolerances for technical drawings. It simplifies blueprints by providing a standardized set of allowable deviations for dimensions that do not have explicitly stated tolerances.
Without a general tolerance reference in the title block, every machine shop interprets untoleranced dimensions differently. Some default to national standards, others guess. ISO 2768 eliminates that ambiguity with a single, globally understood callout.
handles the "hidden" tolerances of features, such as straightness, flatness, symmetry, and circularity. It ensures that even if a length is correct, the part is still physically usable (e.g., it isn't twisted or bowed). Tolerance Classes (Part 2) Part 2 uses three classes: H: High Precision K: Standard Precision L: Low Precision Key Geometrical Tolerances (Part 2)
Table 2: Permissible Deviations for Broken Edges (External Radii & Chamfers) Values are in millimeters ( Tolerance Class over 3 to 6 (Fine) ±0.2plus or minus 0.2 ±0.5plus or minus 0.5 ±1.0plus or minus 1.0 m (Medium) ±0.2plus or minus 0.2 ±0.5plus or minus 0.5 ±1.0plus or minus 1.0 c (Coarse) ±0.4plus or minus 0.4 ±1.0plus or minus 1.0 ±2.0plus or minus 2.0 v (Very Coarse) ±0.4plus or minus 0.4 ±1.0plus or minus 1.0 ±2.0plus or minus 2.0 The Zeiss ISO 2768-2 PDF shows that these
Below is the essential tolerance table for , based on data from the standard. The table below uses data from the standard, where tolerance values for the same nominal range and class may vary slightly based on the specific type of dimension.
The notation consists of two parts:
Controls how flat or straight a surface must be.
| Tolerance Class | Permissible Deviation | |:---------------:|:---------------------:| | H | 0.10 | | K | 0.20 | | L | 0.50 | ISO 2768-mK This single callout instructs the manufacturer
For professionals who need quick access to ISO 2768 tolerance tables, several reliable PDF resources are available:
Precision is paramount in aerospace manufacturing. ISO 2768 classes (particularly fine and medium) are used as baseline tolerances for non-critical dimensions on structural components, brackets, and housings.
: For critical fits like bearings or shafts, professionals recommend using more specific standards like alongside ISO 2768. Xometry Pro Accessing the Standard