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General Tolerance Iso — 2768-mk

Understanding ISO 2768-mk: General Tolerances for Linear & Angular Dimensions

Circular Run-out

For Class K, the general tolerance for circular run-out is fixed at 0.2 mm.

Linear Dimensions (Lengths, widths, depths)

| Nominal Size Range (mm) | Tolerance ‘m’ (± mm) | | :--- | :--- | | 0.5 to 3 | 0.1 | | >3 to 6 | 0.1 | | >6 to 30 | 0.2 | | >30 to 120 | 0.3 | | >120 to 400 | 0.5 | | >400 to 1000 | 0.8 | | >1000 to 2000 | 1.2 |

References / next step

Obtain ISO 2768‑1 and ISO 2768‑2 (latest edition) for authoritative tables and exact angular/form tolerances.

Would you like a printable one‑page PDF with the exact ISO table values filled in (I will include the numeric tables from the standard)?

ISO 2768-mK is an international manufacturing standard used to simplify technical drawings by providing a "default" set of tolerances for features that do not have specific values written next to them. This callout ensures that every part of a drawing is controlled without the need to clutter it with repetitive data, balancing precision with manufacturing efficiency. Understanding the "mK" Notation general tolerance iso 2768-mk

The suffix "mK" combines two distinct parts of the ISO 2768 standard:

m (Medium): Refers to ISO 2768-1. This part defines general tolerances for linear and angular dimensions, such as lengths, diameters, radii, and chamfers.

K (Tolerance Class K): Refers to ISO 2768-2. This part covers geometrical tolerances (GD&T) for features like flatness, straightness, parallelism, and perpendicularity.

ISO 2768-1: General Tolerances for Linear and Angular Dimensions (The "m") Understanding ISO 2768-mk: General Tolerances for Linear &

ISO 2768-1 uses four classes: f (fine), m (medium), c (coarse), and v (very coarse). The "m" class is the most common industry standard for CNC machining and general metalwork. Nominal Dimension Range (mm) Tolerance for "m" Class (mm) ±plus or minus Over 3 to 6 ±plus or minus Over 6 to 30 ±plus or minus Over 30 to 120 ±plus or minus Over 120 to 400 ±plus or minus Over 400 to 1000 ±plus or minus Data sourced from standard ISO 2768-1 charts. ISO 2768-2: General Geometrical Tolerances (The "K")

Geometric Tolerance Values (Class K)

| Tolerance Type | Nominal Size Range (mm) | Tolerance Value (mm) | | :--- | :--- | :--- | | Straightness & Flatness | Up to 10 | 0.05 | | | Over 10 up to 30 | 0.1 | | | Over 30 up to 100 | 0.2 | | | Over 100 up to 300 | 0.4 | | | Over 300 up to 1000 | 0.6 | | Perpendicularity | Up to 100 | 0.4 | | | Over 100 up to 300 | 0.6 | | | Over 300 up to 1000 | 0.8 | | Symmetry | Up to 100 | 0.6 | | | Over 100 up to 300 | 1.0 | | | Over 300 up to 1000 | 1.5 |

5.2 Manufacturing Considerations

A feature for ISO 2768-mk establishes a "medium" precision standard for parts, ensuring they are manufactured within acceptable limits for both size and shape without requiring individual tolerance callouts for every dimension. The designation breaks down into two parts:

m (Medium): Governed by ISO 2768-1, this defines permissible deviations for linear and angular dimensions, such as lengths, radii, and chamfers. Would you like a printable one‑page PDF with

k (Class K): Governed by ISO 2768-2, this covers geometric characteristics like flatness, straightness, and circular runout. Tolerance Tables for ISO 2768-mk

The following values apply based on the nominal size of the feature: Linear Dimensions (Class m)

For linear measurements like external/internal sizes, heights, and distances. Nominal Range (mm) Tolerance (± mm) 120 to 400 400 to 1000 Geometric Tolerances (Class K)

For shape and position characteristics without individual indications. Feature Type Range (mm) Tolerance (mm) Straightness/Flatness 100 to 300 Perpendicularity Symmetry Run-out (Circular) All ranges Key Implementation Details

The Basics Of General Tolerance Standard - ISO 2768-mK - LEADRP

This report is designed as a practical guide for engineers, drafters, and quality control inspectors to understand, apply, and inspect tolerances based on this standard.