Iso 2768-mh Tolerance Chart -

The ISO 2768-mh standard is a globally recognized guideline used in mechanical engineering to simplify technical drawings by defining general tolerances for linear and angular dimensions. When a drawing specifies "ISO 2768-mh" in its title block, it establishes a default level of precision for every feature that doesn't have a specific, individual tolerance applied to it. Breaking Down "mH"

The designation is split into two parts, representing different tolerance classes:

m (Medium): Refers to Part 1 of the standard, covering linear and angular dimensions (e.g., lengths, diameters, radii).

H (High): Refers to Part 2 of the standard, covering geometrical tolerances like straightness, flatness, and perpendicularity. ISO 2768-1: Linear Dimensions (Class m)

The "m" (medium) class is the most common standard used in CNC machining. It provides a balanced approach between manufacturing cost and part functionality. Nominal Size Range (mm) Tolerance (± mm) Over 3 to 6 Over 6 to 30 Over 30 to 120 Over 120 to 400 Over 400 to 1000 Over 1000 to 2000 Over 2000 to 4000 Source: ZEISS Quality Forum ISO 2768-2: Geometrical Tolerances (Class H)

The "H" class defines the permissible limits for the form and position of features. iso 2768-mh tolerance chart

Straightness & Flatness: Ranges from 0.02 mm for lengths up to 10 mm, up to 0.5 mm for lengths over 1000 mm.

Perpendicularity: Ranges from 0.2 mm to 0.5 mm depending on the length of the shorter side. Symmetry: Standardized at 0.5 mm for this class. Circular Run-out: Set at 0.1 mm. Why Use ISO 2768-mh? General Tolerance - ISO 2768 1 & 2 - ZEISS Quality Forum

ISO 2768-mH designation is a widely used international standard for general tolerances in manufacturing, typically applied when specific tolerance values are not indicated on a drawing. It combines two parts: for medium dimensional accuracy (Part 1) and for high geometrical precision (Part 2). Linear Dimensions (m - Medium)

These tolerances apply to measurements like lengths, widths, diameters, and step distances. Nominal Dimension Range (mm) Tolerance (± mm) Over 3 to 6 Over 6 to 30 Over 30 to 120 Over 120 to 400 Over 400 to 1,000 Over 1,000 to 2,000 Over 2,000 to 4,000 Xometry Standard Tolerances Geometrical Tolerances (H - High Precision)

The "H" class defines strict limits for form and position, such as how straight or perpendicular a feature must be. Straightness and Flatness Range of Nominal Length (mm) Tolerance (mm) Over 10 to 30 Over 30 to 100 Over 100 to 300 Over 300 to 1,000 Over 1,000 to 3,000 The ISO 2768-mh standard is a globally recognized

What is ISO 2768? | CNC Machining Tolerance Standards - Fictiv

2. External Radii and Chamfers (ISO 2768-1 – Class m)

| Nominal Size Range (mm) | Tolerance (mm) | |------------------------|----------------| | 0.5 up to 3 | ±0.2 | | >3 up to 6 | ±0.5 | | >6 up to 30 | ±1.0 | | >30 up to 120 | ±2.0 | | >120 up to 400 | ±4.0 |

Part 1: Angular Dimensions (Class 'm')

For angles, the tolerance is not a fixed degree value but is given as a deviation per length of the shorter leg.

| Nominal Length Range of the Shorter Leg (mm) | Permissible Deviation for Class 'm' | | :--- | :--- | | up to 10 | ± 1° | | >10 up to 50 | ± 0° 30' | | >50 up to 120 | ± 0° 20' | | >120 up to 400 | ± 0° 10' | | >400 | ± 0° 5' |

Interpretation: A 45° angle on a part with a short leg of 60 mm can vary between 44°40' and 45°20'. Part 1: Angular Dimensions (Class 'm') For angles,

3. Tolerance grades and their meaning

ISO 2768 defines tolerance grades for linear dimensions:

• f — fine
• m — medium
• c — coarse
• v — very coarse

Each grade is applied to ranges of nominal sizes. The tolerance for a dimension equals the tolerance value from the chart corresponding to the nominal size and selected grade. The “m” grade gives moderate tolerances suitable for general machining.

ISO 2768‑1 also provides default angular tolerances (e.g., ±1° for coarse grades, ±0.5° for medium — see the standard for exact figures) and for unspecified radii/chamfers.

ISO 2768‑2 provides default values for geometrical tolerances when such symbols are omitted, but it is safer to specify geometric controls directly when required.