EN ISO 129-1:2019 PDF

Overview

EN ISO 129-1:2019 (ISO 129-1:2018) defines the general principles for the presentation of dimensions and tolerances in technical product documentation (TPD). It focuses on clear, consistent representation of dimensional information on 2D technical drawings across disciplines and can also be applied to 3D annotation. This standard describes how to present dimension lines, values, symbols and related graphical elements to create unambiguous, machine- and human-readable documentation of the nominal model of a part or assembly.

Key topics and technical requirements

• Presentation rules for dimensions: rules for dimension placement, repeated dimensions, out-of-scale and auxiliary dimensions, and presentation of theoretically exact and symmetrical dimensions.
• Elements of dimensioning: specification of dimension lines, extension lines, terminators, origin presentation, leader lines, and placement of dimensional values and symbols.
• Units and character presentation: guidance on units of measure and alphanumeric character use for dimensional values.
• Special dimensions: arrangements for diameters, radii, spheres, arcs, chords, angles, squares, equally spaced and repeated features, and dimensioning of thin parts or restricted areas.
• Dimensional tolerances - presentation only: how to present tolerance indications (limit deviations, limit dimensioning) without prescribing tolerance interpretation or application.
• Introduced concepts: property indicators, developed length, between, surface indicators, flag notes, and textual instructions to clarify dimensional intent.
• Arrangement methods: chain, parallel and running dimensioning, and tabular dimensioning rules.
• Scope limitation: ISO 129-1 covers presentation only - it does not define tolerancing principles or the meaning of dimensional tolerances. It applies to the nominal model, not the non-ideal (skin) model used for tolerancing.

Practical applications and users

Who uses ISO 129-1:

• Mechanical and civil design engineers, CAD drafters and technical illustrators
• Manufacturing planners, machinists and quality inspectors
• Documentation and QA teams preparing drawings for procurement, production or certification
• Standards committees and technical authors aligning drawing practices across organizations

How it’s used:

• Create consistent 2D drawings and 3D annotations for production and inspection
• Ensure unambiguous communication of dimensional intent between design, manufacturing and inspection
• Improve CAD drawing templates, drawing checks and automated annotation rules
• Support contractual and regulatory documentation where standardized presentation is required

Related standards

• ISO 14405 (tolerancing principles) - consult for tolerancing meaning and application
• ISO 29845 - for additional drawing types where rules are applied
• GPS standards (normative references/bibliography) for advanced tolerancing and skin model considerations

Keywords: ISO 129-1, technical product documentation, TPD, presentation of dimensions and tolerances, 2D drawings, dimensioning, CAD annotation, property indicators.