We noticed you’re not on the correct regional site. Switch to our AMERICAS site for the best experience.
  • BS 949-2:1992

    Current The latest, up-to-date edition.
    Add to Watchlist
    This Standard has been added successfully to your Watchlist
    Please visit My Watchlist to see all standards that you are watching.
    Please log in or to add this standard to your Watchlist.
    We could not add this standard to your Watchlist.
    Please retry or contact support for assistance.
    We could not add this standard to your Watchlist.
    Please retry or contact support for assistance.
    You have already added this standard to your Watchlist.
    Visit My Watchlist to view the full list.

    Screwing taps Specification for unified ground thread taps. Manufacturing tolerances

    Available format(s):  Hardcopy, PDF

    Language(s):  English

    Published date:  15-12-1992

    Publisher:  British Standards Institution

    Add to Watchlist

    Add To Cart

    Table of Contents - (Show below) - (Hide below)

    Committees responsible
    Foreword
    Specification
    1. Scope
    2. References
    3. Right-hand and left-hand threads
    4. Tolerance classes of taps
    5. Dimensions and manufacturing tolerances of the
         threaded portion
    6. Marking
    Annexes
    A. (informative) Bases of calculation of the
         tolerances on the threaded portion of taps for
         Unified threads
    B. (informative) Example of calculation of the
         dimensions of the threaded portion of a tap
    C. (normative) Taps for BSW, BSF and BA threads
         (obsolescent)
    Tables
    1. Formulae for limits of tolerance for ground thread
         taps for Unified threads
    2. Dimensions and manufacturing tolerances for the
         threaded portion of UNC taps
    3. Dimensions and manufacturing tolerances for the
         threaded portion of UNF taps
    4. Tolerances on cumulative pitch for ground thread
         taps for Unified threads
    A.1 Values of elements based on pitch in basic formulae
         for taps for Unified threads
    A.2 Values of elements based on nominal diameter in
         basic formulae for taps for Unified threads
    A.3 Values of elements used in calculating the minor
         diameter from a measured value of the pitch
         diameter of a tap for Unified threads
    A.4 Tolerances on thread angle of taps for Unified
         threads
    B.1 Calculation of the dimensions of a ground thread
         5/8 - 11 UNC tap, class 2
    C.1 Dimensions and manufacturing tolerances for the
         threaded portion of BSW taps
    C.2 Dimensions and manufacturing tolerances for the
         threaded portion of BSF taps
    C.3 Dimensions and manufacturing tolerances for the
         threaded portion of BA taps, class 2
    C.4 Formulae for limits of tolerance for taps for BSW,
         BSF and BA threads
    C.5 Values of elements based on pitch in basic formulae
         for BSW and BSF threads
    C.6 Values of elements based on nominal diameter in
         basic formulae for BSW and BSF threads
    C.7 Values of elements used in calculating the minor
         diameter from a measured value of the pitch
         diameter of a tap for a BSW or BSF thread
    C.8 Values of elements used in calculating the minor
         diameter from a measured value of the pitch
         diameter of a tap for a BA thread
    Figures
    1. Relationship of tap classes to nut tolerances
    A.1 Minimum values of tap major diameter d
    A.2 Tap minor diameter d1
    List of references

    Abstract - (Show below) - (Hide below)

    Specifies tolerances and dimensions for screwing taps for various threads. Coverage includes: right-hand and left-hand threads; tolerance classes of taps; marking; dimensions and manufacturing tolerances of the threaded portion. Also includes annexes, tables and diagrams.

    General Product Information - (Show below) - (Hide below)

    Committee W/-
    Development Note Supersedes BS 949-2(1979) (12/2004) Supersedes 90/79112 DC (10/2005) Reviewed and confirmed by BSI, January 2011. (12/2010)
    Document Type Standard
    Publisher British Standards Institution
    Status Current

    Standards Referencing This Book - (Show below) - (Hide below)

    BS 93:1951 SPECIFICATION FOR BRITISH ASSOCIATION (B.A.) SCREW THREADS WITH TOLERANCES FOR SIZES 0 B.A. TO 16 B.A.
    BS 1580-3:1965 SPECIFICATION FOR UNIFIED SCREW THREADS - DIAMETERS BELOW 1/4 IN AND LARGER
    BS 949-3:1982 Screwing taps Specification for taps for pipe threads (G series, Rp series and Rc series)
    BS 1580-1&2(1962) : 1962 SPECIFICATION FOR UNIFIED SCREW THREADS - DIAMETERS 1/4 INCH AND LARGER
    BS 84:1956 SPECIFICATION FOR PARALLEL SCREW THREADS OF WHITWORTH FORM
    BS 949-5:1990 SCREWING TAPS - NOMENCLATURE AND TERMINOLOGY
    • Access your standards online with a subscription

      Features

      • Simple online access to standards, technical information and regulations
      • Critical updates of standards and customisable alerts and notifications
      • Multi - user online standards collection: secure, flexibile and cost effective
Need help?
Call us on 131 242, then click here to start a Screen Sharing session
so we can help right away! Learn more