BS EN ISO 129-1:2019+A1:2021

What is ISO 129‑1 about?  

ISO 129‑1 establishes the general principles for presentation of dimensions and associated tolerances that apply to 2D technical drawings in all disciplines and trades but which can also be applied to 3D applications. 

In addition, ISO 129‑1 introduces the concept of property indicators, developed length, between, surface indicators, flag notes and textual instructions. 

Note: ISO 129‑1  does not cover the application of dimensional tolerances and their meaning, and can only be used to describe the nominal model of a drawing, not the non-ideal surface model (skin model) used for tolerancing purposes. 

Who is ISO 129‑1 for? 

ISO 129‑1 on dimensions and tolerances for TPD is beneficial to various industries such as aerospace, defence, automotive, rail and other general manufacturing sectors. Specific users include:  

• Mechanical engineers 
• Design engineers 
• Engineering designers 
• Architecture and design agencies 

Why should you use ISO 129‑1? 

Technical product documentations play a crucial role in explaining the important aspects of a product such as use, functionality, creation, or architecture of a product. It not just captures data but also presents it in a simple manner. Technical product documentation provides essential information about a product or service to a person or organization which them to achieve optimum efficiency in their products. ISO 129‑1 enlists and explains numerous types of elements of dimensioning which will help you gain a solid understanding of the elements of dimensioning. 

ISO 129‑1 explains presentation of dimensions that include graphical and letter symbols with dimensional values that will help you to identify the feature characteristics. Moreover, ISO 129‑1 also provides solutions if the limits of a feature characteristic are ambiguous. 

Overall, ISO 129‑1 can help your business avoid misinterpretation and improve readability, resulting in precise specification and permissible tolerances of products for optimum efficiency, ultimately widening the market reach for your product.   

What’s changed since the last update?  

BS EN ISO 129‑1:2019+A1:2021 on technical product documentation for presentation of dimensions and tolerances supersedes BS EN ISO 1291:2019, which is withdrawn. 

BS EN ISO 129‑1:2019+A1:2021 includes some technical changes with respect to BS EN ISO 1291:2019. These include: 

• ISO 129‑1:2019+A1:2021 does not cover the application of dimensioning tolerances has been clarified 
• Property indicator, surface indicator, developed length and between symbols have been discussed 
• Flag notes and textual instructions have been discussed 
• Dimensioning repeated features and restricted areas have been clarified