BS ISO 3353-2:2020 pdf free.Aerospace一Lead and runout threads.Internal threads.
BS ISO 3353-2 1 Scope This document specifies the lead and runout thread and undercut requirements for internal threads (blind tapped holes) for aerospace construction. It is applicable whenever it is referenced in a definition document. 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 5855-1, Aerospace一M] threads一Part 1: General requirements 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses:  一ISO Online browsing platform: available at https://www.iso.org/obp 一IEC Electropedia: available at http://www.electropedia.org/3.1 lead thread portion of the incomplete thread that is fully formed at the root but not at the crest which occurs at the beginning end of either an external or internal thread 3.2 runout thread part of the screw thread in which is located the thread incompletely formed during cutting, between the completely formed threads and the end of the cylindrical part of the blind tapped hole 3.3 undercut groove dug at the hole bottom to limit the threads with completely formed thread (except at the crossing between the last thread and the groove flank) 3.4 completely formed thread thread, the profile of which (ABC) is located, over an axial distance of 1P, within the limits specified in the definition document for the thread. BS ISO 3353-2 pdf download.