BS ISO 2904:2020

What is ISO 2904 about?  

ISO 2904 specifies the basic dimensions of ISO metric trapezoidal screw threads by ISO 2902. The values refer to the design profiles by ISO 2901. 

ISO 2904 is chiefly applicable to traversing threads for traversing motion on machines, tools, etc. It can also be used for fastening threads. 

Who is ISO 2904 for?  

ISO 2904 on ISO metric trapezoidal screw threads is relevant to: 

• Manufacturers and suppliers of ISO metric trapezoidal screw threads 
• Users of ISO metric trapezoidal screw threads 

Why should you use ISO 2904?  

The trapezoidal metric thread form is similar to the Acme thread form, except the thread angle is 30°. 

ISO 2904 provides the basic dimensions such as nominal diameters, pitch, pitch diameter, major diameter, the minor diameter of ISO metric trapezoidal screw threads. 

As a user of ISO 2904, you can be ensured of the basic dimensions of ISO metric trapezoidal screw threads. ISO 2904 assists the users in manufacturing or purchasing trapezoidal screw threads of the required dimension. ISO 2904 standard gives clear guidelines which will help those making, selling, and using ISO metric trapezoidal screw threads to achieve greater business efficiency. 

What’s changed since the last update?  

BS ISO 2904:2020 together with BS ISO 2901:2016, BS ISO 2902:2016, BS ISO 2903:2016, and BS ISO 965‑1:2013, supersedes BS 5346:1976, which is withdrawn. 

The main changes compared to the previous edition are as follows: 

• In Clause 1 (Scope) the phrase “basic profiles” has been replaced by “design profiles”. 
• In Clause 1 (Scope) the second paragraph has been added. 
• Clause 3 (Terms and definitions) has been added. 
• “BASIC PROFILES (modified)”, the title of ISO 2904:1977, Clause 4, has been replaced by “Basic dimensions”, the title of ISO 2904:2019, Clause 5. 
• Table 1 has been deleted.