1、BS 919-1:2007S c r e w g a u g e l i m i t s a n d t o l e r a n c e s Part 1: Specification for gauges for screw threads of unified formICS 21.040.30NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDIncorporating Corrigendum No.1Publishing and copyright informati
2、onThe BSI copyright notice displayed in this document indicates when the document was last issued. BSI 200ISBN978 0 5809The following BSI references relate to the work on this standard: Committee reference TDW/4 Draft for comment 07/30158512 DCPublication historyFirst published April 1952 Second edi
3、tion,December 1960 Third edition, November 2007Amendments issued since publicationAmd. no. Date Te xt a f f e c t e dBS 919-1:20076C1 See foreword6 58630 September 20096 BSI 200 iBS 919-1:2007ContentsForeword iii1 Scope 12 Normative references 13 Terms and definitions andsymbols 14 Design 25 Toleran
4、ces and thread forms 36 Marking 25AnnexesAnnex A (informative) Verifying conformity with BS 1580 26Annex B (informative) Conventional illustration of tolerance zones 34Annex C (informative) Effective diameter equivalent of pitch and angle errors 34Annex D (informative) A system of gauging for screw
5、threads before and after coating 37Annex E (informative) Setting to size of adjustable screwring gauges 40Annex F (informative) Comparison between the designations of British and American gauges 42Annex G (informative) Tolerances for major, effective and minor diameters and flank angle and pitch 43A
6、nnex H (informative) Hardness 44Bibliography 45List of figuresFigure 1 Disposition of effective diameter tolerance zones for screw gauges 18Figure 2 Thread forms of GOgauges 20Figure 3 Thread forms of NOT GO gauges 21Figure 4 Forms of thread for NOT GO effective diameter screw gauges 22Figure 5 Thre
7、ad forms of setting plugs 24Figure B.1 Limits and tolerancesfor the effective diameters of internal and external threads 34List of tablesTable 1 Tolerances for GOscrew plug gauges all classes 5Table 2 Tolerances for NOT GOscrew plug gauges all classes 6Table 3 Tolerances for GOand NOT GO plain plug
8、gauges for minordiameters 7Table 4 Tolerances for GOscrew ring gauges solid type, all classes 7Table 5 Tolerances for NOT GO effective diameter screw ring gauges solid type, all classes 8Table 6 Tolerances for GOscrew check plugs for GOscrew ring gauges solid type 8Table 7 Tolerances for NOT GOeffec
9、tive diameter check plugs for new GO screw ring gauges solid type 99BS 919-1:2007ii BSI20Table 8 Tolerances for NOT GO effective diameter check plugs for worn GOring screwgauges solid type 9Table 9 Tolerances for GO screw check plugs for NOT GO effective diameter ring gauges solid type 10Table 10 To
10、lerances for NOT GO screw check plugs for NOT GO effective diameter ring gauges solid type 10Table 11 Tolerances for GO and NOT GO plain check plugs for the minor diameters ofGO and NOT GO screw ringgauges solidtype 10Table 12 Tolerances for adjustableGO screw ring and calliper gauges for all classe
11、s 11Table 13 Tolerances for adjustable NOT GO screw ringand calliper gauges for all classes 12Table 14 Tolerances for double length setting plugs for adjustable GOscrew ringgauges 13Table 15 Tolerances for double lengthsetting plugs for adjustable NOT GO screw ring gauges 14Table 16 Tolerances forsi
12、ngle length setting plugs for adjustable GO screw calliper gauges 15Table 17 Tolerances for single length setting plugs for adjustable NOT GO screw calliper gauges 15Table 18 Tolerances for GO and NOT GO plain calliper(GAP) gauges for major diameters 16Table 19 Constants for use incalculating gauge
13、dimensions (inch) 17Table C.1 Effective diameterequivalents of errors in pitch 35Table C.2 Effective diameter equivalents of errors in flank angles 36Table D.1 External threads with specified allowances which have to be maintained after coating Unified threads, Class 1A 38Table D.2 External screw th
14、reads with specified allowances (in the uncoated condition) which can be absorbed by the coating Unified threads, Class 2A 38Table D.3 External screw threads with no specified allowance Unified threads, Class 3A 39Table D.4 Unified threads, Classes 1B and 2B 39Table D.5 Unified threads, Class 3B 39T
15、able D.6 Summary ofGO and NOT GO screw gauges and plain gauges for checking unified threads 40Summary of pagesThis document comprises a front cover, an inside front cover, pagesitoiv, pages 1 to 45 and a back cover.9 BSI 200 iiiBS 919-1:2007F o r e w o r dPublishing informationThis British Standard
16、is published by BSI and came into effect on 30 November 2007. It was prepared by Subcommittee SFTSE/1, Screws and fasteners technical specification committee, under the authority of Technical Committee TDW/4, Technical product realization. A list of organizations represented on thesecommitteescan be
17、 obtained on request to their secretaries.BS 919, Screw gauge limits and tolerances is in four parts:Part 1: Specification for gauges for screw threads of unified formPart 2: Specification for gauges for screw threads of Whitworth and B.A. formsPart 3: Specification for gauges for screw threads of I
18、SO metric formPart 4: Limits of size for gauges for screw threads of unified form diameters in and largerSupersessionThis Part of BS 919 supersedesBS 919-1:1960, which is withdrawn.Relationship with other publicationsThis British Standard isintended for use with BS 1580, which specifies the correspo
19、nding screw threads.Information about this documentThis British Standard has been fully revised to bring it up to date.Presentational conventionsThe provisionsof this standard are presented in roman (i.e. upright) type. Its requirements are expressed in sentences in which the principal auxiliary ver
20、b is “shall”.Commentary, explanation and general informative material is presented in notes in smaller italic type, and does not constitute a normative element.Contractual and legal considerationsThis publication does not purport to include all the necessaryprovisions of a contract. Users are respon
21、sible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.14- - -The start and finish of text introduced or altered by orrigendum No. 1 is indicated in the text by tags PQ.9Civ BSI20 This page deliberately left blankBS 919-1:20079 BSI 200 1BS
22、919-1:20071ScopeThis part of BS 919 specifies requirements for the following types of gauges intended for usein the checking of products with unified screwthreads for conformity with BS 1580.a) Screw gauges:1) solid screw plug gauges, GO and NOT GO;2) solid screw ring gauges, GO and NOT GO;3) adjust
23、able screw ring gauges, GO and NOT GO;4) adjustable screw calliper gauges GO and NOT GO.b) Setting plugs for adjustable ring gauges and for calliper gauges,GO and NOT GO:1) double length;2) single length.c) Screw check plugs for solid screw ring gauges, GO and NOT GO.d) Plug gauges and calliper gaug
24、esfor the crest diameters of product threads, GO and NOT GO.Annex A gives information about the various types of gauges covered by BS 919. Annex B explains the conventional method for showing the tolerance zones of gauges. Guidanceon the calculation of the effective diameter equivalent of pitch and
25、angle errors is given inAnnex C.Annex D recommends a method for gauging screw threads before andafter coating.Notes on the setting to size ofadjustable screw ring gauges are presented in Annex E, whileAnnex F presents a comparison of British and American screw thread terminology. Annex G discusses t
26、he tolerances for major, effective and minor diameters and flank angle and pitch permitted by BS 1580. Guidance on the hardnessof gauges is given in Annex H.2NThe latest edition of the following referenced document (including any amendments) is indispensable for the application of this document. BS
27、1044-1, Specification for gauge blanks Part 1: Plug, ring and calliper gauges3Terms and definitions and symbols3.1 Terms and definitionsFor the purposes of this part of BS919, the terms anddefinitions given in BS 6528:1984 and the following apply.3.1.1 effective diameterdiameter of the pitch cylinde
28、rNOTE 1 This is the “simple” effective diameter, as distinct from the “virtual” effective diameter (see3.1.2).NOTE 2 Also known as “pitch diameter”.BS 6528:1984, Glossary of terms for cylindrical screw threadsP Q9BS 919-1:20072 BSI203.1.2 virtual effective diametereffective diameter of an imaginary
29、threadof perfectpitch and flank angle, having the full depth of flanks, but clear at the crests and roots, which would just assemble with the actual thread over the prescribed length of engagementNOTE The “virtual” effective diameter exceeds the effective diameter in the case of an external thread,
30、but is less than the effective diameter in the case of an internal thread, by an amount corresponding to the combined diametral effects due to any errors in the pitch and/or the flank angles of the thread.3.2 SymbolsFor the purposes of this part of BS 919, the following symbols apply.NOTE 1 These ar
31、e repeated from BS 6528 for the convenience of users of this standard.D major diameter of internal thread D1minor diameter of internal threadD2effective diameter of internal thread (see Note 2)d major diameter of external threadd1minor diameter of external threadd2effective diameter of external thre
32、ad (see Note 2)H height of fundamental triangleP pitchNOTE 2 These are the symbols given for pitch diameter in BS 6528.4D4.1 GeneralThe general dimensions of blanks suitable for both screwand plain gauges shall conform to BS 1044-1.4.2 F e a t h e r e d g e sTo avoid feather edges onscrewplug andrin
33、g gauges and setting plugs,the partial thread at both ends ofthe gauge shall be removed to a blunt start, except for:a) screw plug gauges and setting plugsin sizesbelow 0.150 inand/orwithexternal cone centres; andb) screw ring gauges inch nominal size and smaller or with pitches of 20 threads per in
34、ch and finer,and all screw plug gauges andsetting plugs with pitches of 28 threads per inch and finer for which a 60 chamfer from the axis ofthe gauge is permitted in lieu of the removal of the partial thread. Not more than one complete turn of the thread shall be removed to the point where the full
35、 thread form is obtained.On double length setting plugs with pitches of 28 threads per inch and coarser, where the truncated portion meets the full form portion, the feather edge shall be completely removed.12- - -9 3BS 919-1:20074.3 Dirt clearance groovesWhen specified by the user, screw plug gauge
36、s shall have a dirt clearance groove cut axial to the thread to a depth slightly below the rootof the threadandat the position wherethe thread commences at its full section, as specified in 4.2.4.4 Removal of sharp edgesAll sharp edges on the gauging portions and handles shall be removed.5TcfNOTE Si
37、nce smallinaccuracies in size and form of gauges are inevitable in their manufacture, tolerances are specified to control these inaccuracies to a degree which is both practical and economical.Attention has to be paid to the product tolerance and care taken that the gauge tolerance does not unduly ab
38、sorb, or add to, the product tolerance, though it is not possible to lay down a hard and fast relationship betweengauge tolerance and product tolerance in the case of screw gauges.Absorption of product tolerance by the gauge tolerance depends upon the position of the gauge tolerance zone in relation
39、 to the product tolerance zone. Figure 1 illustrates the relative dispositions of gauge and product tolerance zones, using the conventional methods of showing tolerance zones explained in Annex B. 5.1 Screw plug gaugesThe tolerance zones for GOand NOT GOscrew gaugesshall be asshown in Figure 1.Toler
40、ances for GO screw plug gauges and for NOT GO effective diameter screw plug gauges shall be as specified in Table 1 and Table 2, respectively.The form ofthread for GO screwplug gaugesshall be asshown in Figure 2a).NOTE Figure 3a) indicates the profile of a gauge which, theoretically, would verify th
41、at the thickness of the product thread is not less than half the basic pitch at a diameter equal to the minimum metal limit specified for the effective diameter of the product thread. Such a gauge would notonly be difficult to measure but would also wear very quickly in use. The gauge is made practi
42、cable, however, by providing it with limited lengths of flank, as shown in Figure 3b). The longer these flanks, the less critical does the gauge become in controlling the effective diameter of the product thread when the flank angles are in error or when other malformations exist. Alternative forms
43、of thread for NOT GO effective diameter screw plug gauges are shown in Figure 4. Figure 4a) shows a short flank (or low addendum) gauge having an addendum of H/8, while Figure 4b) shows a long flank (or high addendum) gauge with an addendum of H/4. A long flank NOT GO effective diameter gauge is les
44、s effective than a short flank gauge in detecting thin threads when angle errors are present, or when other malformations of the threadexist such asthose due to tearing.Guidance on the selection of gauges is given in BS 1580.The Americantypehigh addendum NOT GO effective diameter screw plug gauge sh
45、ould be used for checking the numbered sizes of internal threads. BSI 2009BS 919-1:20074 BSI5.2 Plain plug gaugesThe disposition of the tolerance zones for plain plug gauges shall be as shown in Figure 1.Tolerances for GO and NOT GO plain plug gauges for minor diameters ofinternal threads shall beas
46、 specified in Table 3.5.3 Screw ring gauges and callipersThe disposition ofthe tolerance zones for GO and NOT GO screw ring gauges and callipers shall be as shown in Figure 1.Tolerances for GO screw ring gauges, solid type,andfor NOT GO effective diameter screw ring gauges, solid type, shall be as s
47、pecified in Tables 4 and Table 5, respectively.Tolerances for GO and NOT GO screw check plugs, and for GO and NOT GO plain check plugs for use in testing GO and NOT GO screw ring gauges, solid type, shall be as specified in Table 6to Table11.Tolerances for adjustable GOand NOT GOscrewring and callip
48、ergauges shall be as specifiedin Tables 12 and Table 13. NOTE 1 No tolerances are given in the tables for the effective diameter because calliper gauges and adjustable ring gauges are set to size by means of setting plugs.The form of thread for GO screw ring gauges, solid and adjustable, and callipe
49、r gauges shall be as shown inFigure 2b). The form of thread forNOT GO screw ring gauges(solid and adjustable) and NOT GO callipe gauges shall beasshown in Figure 4c).NOTE 2 This is the same form as that used in the USA for LO ring gauges.See A.2.6, Note.NOTE 3 Since adjustable ring gauges are set to size on effective diameter by means of setting plugs, no tolerances are shown for the effectivediameters of the gauges. Nevertheless, it is important that the ring gauge i
