BS ISO 2904:2020 pdf free
BS ISO 2904:2020 pdf free.ISO metric trapezoidal screw threads – Basic dimensions
This document specifies the basic dimensions of ISO metric trapezoidal screw threads in accordance with ISO 2902. The values refer to the design profiles in accordance with ISO 2901.This document is chiefly applicable to traversing threads for traversing motion on machines, tools, etc. It can also be used for fastening threads.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 5408, Screw threads一Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5408 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
一ISO Online browsing platform: available at htts://www.iso.org/obp
一IEC Electropedia: available at http://www.electropedia.org/
4 Symbols
For the purposes of this document, the fllowing symbols apply.
D1 basic minor diameter of internal thread
D2 basic pitch diameter of internal thread
D4 basic major diameter of internal thread
d basic major diameter of external thread (nominal diameter)
d2 basic pitch diameter of external thread
d3 basic minor diameter of external thread
P pitch
ac clearance at major and minor diameters
R1 radius on crest corners of external thread on design profile
R2 radius on root corners of internal and external threads on design profile
5 Basic dimensions
Basic dimensions shown in Figure 1 are given in Table 1.The values of D1, D2, D4, d2 and d3, in Table 1, have been calculated from the following formulae and rounded to the third decimal place.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.BS ISO 2904 pdf free download.
