Acme Thread Dimensions

7/27/2019 Acme Thread Dimensions

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THEATIONALBUREAUOFSTANDARDSFunctionsandActivities

ThefunctionsoftheNationalBureauofStandardsar esetforthin theActofCongress,March3,1901,asamendedbyongressnublicaw619,950.hesencludeheevelopmentndmaintenanceofthenationalstandardsofmeasurementan dth eprovision of meansandmethodsformakingmeasurementsconsistentwiththesestandards;th edeterminationofphysicalconstantsan dpropertiesof materials;th edevelopmentofmethodsan dinstrumentsfortestingmaterials,devices,an dtructures;advisoryervicestogovernmentagenciesoncientifican dtechnicalproblems;in -ventionanddevelopmentofdevicestoservespecialneedsof th eGovernment;an dth edevelopmentoftandardpractices,odes,an dpecifications.heworkncludesbasican dappliedesearch,development,ngineering,nstrumentation,esting,valuation,alibrationervices,ndariousconsultationan dinformationservices.esearchprojectsar ealsoperformedforothergovernmentagencieswhentheworkrelatestoan dsupplementsthebasicprogramoftheBureauorwhenheBureau'suniqueompetencesequired.hecopeofactivitiessuggestedbyheistingofdivisionsan dsectionsonth einsideofth ebackcover.Publications

Theresultsofth eBureau'sworktaketh eformofeitheractualequipmentan ddevicesorpub-lished papers.hesepapersappear either inth eBureau's ownseries ofpublications or inth ejournalsofprofessionalandscientificsocieties.heBureauitselfpublishesthreeperiodicalsavailablefrom theGovernmentPrintingOffice:heournalofResearch,publishednou reparateections,presentscompletecientificandechnicalpapers;heTechnicalNewsBulletinpresentsummaryandpreliminaryeportsonworknprogress;an dBasicRadioropagationredictionsprovidedataordeterminingthebestrequenciestouseorradiocommunicationsthroughoutheworld.Therear ealsofiveseriesofnonperiodicalpublications: onographs,AppliedMathematicsSeries,Handbooks,MiscellaneousPublications,an dTechnicalNotes.Informationon th eBureau'spublications ca nbefoundinNBSCircular460,Publicationsofth eNationalBureauofStandards($1.25)an ditsSupplement($1.50),availablefromtheSuperintendentofDocuments,GovernmentPrintingOffice,Washington25,D.C.


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UNITEDTATESDEPARTMENTOFOMMERCE; .j FREDERICKH.MUELLER,ecretaryNATIONALUREAUF STANDARDS ,A .V .A S T W ,Director

NATIONALUREAUOFT A N D A R D SHANDBOOKH28195 7 )

S C R E W - T H R E A DT A N D A R D S F O RE D E R A LERVICES

1957 PARTII

A C M E ,TUB CME,A NDBUTTRESSH R E A D S ROL L EDH R E A D SO RCREWHELLSOFLECTRICA M PHOLDERSA N DU NASSEMBLEDA M PASESMICROSCOPEOBJECTIVE NDNOSEPIECEH R E A D S SU RVEYINGNSTRUMENTM O U N T I N GH R E A D SPHOTOGRAPHICEQUIPMENTH R E A D S ISOMETRICH R E A D S ;M I SCEL L ANEOUSH R E A D S CLASS NTERFERENCE-FITH R E A D S ,TRIALT A N D A R D WRENCHOPENINGS

DTICQUALITYINSPECTED 3AmendsinpartH28(1944)an dinpartits1950Supplement)

[IssuedOcober7 ,1960]


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A P P R O V A L E X T H E S E C F B I A R I E S O F D E F E N S E A N D COMCRCE

The a c c o m p a n y i n g H a n d b o o k H 2 8 ( 1 9 5 7 ) , P a r t I I I , on s c r e w - t h r e a ds t a n d a r d s f o r F e d e r a l S e r v i c e s , s u b m i t t e d b y t h e I n t e r d e p a r t m e n t a lS c r e w T h r e a d C o m m i t t e e , i s h e r e b y a p p r o v e d f o r u s e b y t h e D e p a r t m e n t s of D e f e n s e a n d C o m m e r c e .

F o r t h eS e c r e t a r y o f D e f e n s e , of C o m m e r c eHI

Accas ionorD a

NTIS CRAM OTIC TA B Unannounced Justif ication ByDitbut ton/

Availabi l i tyode Oist

MAvai lnd/orSpecia l


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Contents

ForewordPersonnelfheCommitteeApprovalbythemerceSECTIONXII. InterdepartmentalcrewThreadSecretariesfDefensend orn-A c m ethreads..1 .eneralandhistorical2.pecifications fo rAcmeform ofthread3.tandardcm ehreade- Fagsii in 1 1 SECTIONXIII.SECTIONXI\ Nat,

SECTIONV .

SECTIONV

4 .lassificationandtolerances,A c m ethreads5 .imitso f size,A c m e threads.6 .hreaddesignations7 .agesfo rAcmethreads(a )ag etolerances(b )ages for externalthreads(c )ages for internalthreads(d )oncentricityStubAcmethreads1.nr>.eralandhistorical2.pecifications fo rStubAcme formo fthread3.tandardStub cm ethreadseries4 .lassification andtolerances,standard Stub Acmethreads5 .imitso f size,standardStubA c m ethreads6 .hreaddesignations7 .Alternative Stub Acmethreads8.agesorStubcme threads(a)ag etolerances(b )ages for external

threads(e ) Gagea fo r utej'ualtnteads.--.-.AT-!..r-e) GaKinatoensfonb^. i . 'atltffralButtressthreads.,* .-i.1I.Historical..* . IVi. L .2.^5eneral.p$y_......,._,.1 .3 .Specifications....hread.designations'. IIIfIT!It ^m ii ^ i pn 3i_ 6 .ritish standard Buttressthread... nTeTiKhStndardrolledthreadsfo rcrewhel ls eflectric. , i .lam p-hokjers-andor-awewl^eljso fnassembledamp'"bases"1.

SECTIONVII.

'".artfjo fflireacT-..T..2.nrfcad series'....,.1.3 .agtti.-?'.,..'_:._~_ _ Microscopebjective iandose-piece thrqads,0 . 8 0 Q 36AM[ ) . 1 .enerahandhistorical..2.pecifications----X-fiaaedilafipaam.4 .ritishtandardo ricro-scopebjectivendose-piecethreadsSurveying instrument mourningthreads..1 .eneralandhistorical2.pecifications3.ag ed i mens i ons 4 6 710101017 181818181919 20 21 2225 25 2627 27 27 27 27 28 28 3233 34 3 - 1 34 34 35 36 36 36 38 3840 404040 PageSECTIONXVIII.hotographicequipmentthreads. 41 1 .ripod connections fo rAmer icanameras;/t 2 0 U N C 1 A / 1 Bhreads(PH3.6)41 2.Tripod connections fo rEuropeanameras: 1 6 U N C 1 A / 1 B(PH3.7).. 423.Threads for attachingmountedlensestophoto-graphicquipment(PH3.10)4 24 .Attachmentthreadsforlensaccessor ies(PH3.12 ) _4 25 .Shuttercable release tipandsocketwithaperEuro-pean)hreadPH3.23)... 4 5 6 .Shutter cable release tipandocketi thtraight(American) thread(PH3.24)._. 4 5 SECTIONIX. Miscellaneousthreads.4 5 1.0 stubthreads4 5 2.odi f iedsquarethreads4 5 3.Threadso rairyanitaryfittings.. 4 6 4 .lassbottleandjarthreads. 4 6 Appendix0 .Wrenchopenings4 7 Appendix1.lass 5 interference-fit threads,TrialAmericanStandard81.ntroduction 82.cope83.es ignandapplicationdata84.ableso fd i mens i ons ,torques,andinterferences5 25 .xtensiono fthestandard5 2Append ix2.hetightening o f threadedfastenerstopropertension2 1.Micrometermethod2 2.Feel"method..33.orquemeasurementmethod..34 .ngularturno fnutmethod3 5 .seo fspecialdevicesfo rcon-trollingtension5 3 6 .ibliography...5 3 Append ix3.hree-wiremethodo fmeasuremento fpitchdiameterof29 cme,29 tubcme ,nduttressthreads5 4 1.cm eandStubA c m ethreads.. 5 4 (a )ingle-start externalthreads5 4 (b )Multiple-start externalthreads5 5 (c )imitations o f three-wiremeasurementfexternalthreads5 9 2.Buttressthreads5 9 3.ibliographynmeasurementofitchiameterymeans o fwires6 0 Appendix4 .Metricscrew-threadstandards611.SOthreadprofiles612.tandardseriesfo rIS Ometricthreads6 2 3.Designationso rSOetricthreads6 2


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Tables

PageTableXII.1 .Bas ic d imens ions ,generalpurposeA c m e threads.TableXII.2 . Ba si cd imens ions ,centralizingA c m ethreadsTableXII.3 . A c m e threadsseries,basicdiametersand threaddataTableXII.4 . Tole rancesandal lowances(m i n i m um clearances) fo rmajorandminordiameters,A c m e thread seriesTableXII.5.Pitchdiameter al lowances for A c m e threadsTableXII.6.Pitchdiametertolerancesfo rAcme screw threads,classes2G and2C_ _ TableXII..Pitchiameteroleranceso r cm ecrewhreads,lassesG,C,and5CTableXII.8.Pitchiameteroleranceso r cm ecrewhread,lassesG,C, and6C.TableXII.9.Formulasfo rdiameters,A c m e thread classes0 TableXII.10.Limitsfiz endolerances,cm eeneralurposehreaderies, classes 2G,3G, aiid4 G 1TableXII.11.Limitso '.sizeandtolerances, cm ecentralizingthreadseries ,classes2C,3C,and4C3TableXII.1 2 . L i m i tsofsizeandtolerances, cm ecentralizingthreadseries,lasses 5Cand6C4 TableXII.13.Toleranceso rgo"ndnoto"hreadndlainages,cm e threads 7 TableXII.1 4 . Pi tc hdiametercompensationforadjustedlengthsof"go"ringgagesforgeneralpurposeandcentralizingthreads7 TableXIII.1.StandardStubA c m e threadf o r m ,basicd imens ions9 Table XIII.2.StandardStubA c m e threadseries ,basic diametersandthreaddata.. 1 TableXIII.3.Tolerancesandal lowancesfo rmajorandminordiameters,StubA c m ethreads 2TableXIII.4.Pitchdiameteral lowancesfo rStubA c m e threads2TableXIII.5.Limitsof size andtolerances,standardStubA c m e thread series3TableXIII.6.ModifiedForm1Stub A c m e threadf o r m ,basic dimensions5 TableXIII.7.ModifiedForm2StubA c m e threadfo rm,basicd imens ions5 TableXIII.8.Tolerancesfo r"go"and"notgo"threadgages,StubA c m ehreads..6 TableXIII.9.Tolerances fo rplaingages,StubA c m e threads6 TableXIV.1 .Bas ic d imens ions forButtressthreads0 TableXIV.2.Toleranceso n Buttressthreads,class 3(close)0 TableXIV.3.Toleranceso n Buttressthreads,class2(m e d i um )0 TableXIV.4,TolerancesonButtressthreads,class (free)1 TableX I V .5 . A l l o w an c e son externalButtress threads,al l classes1 TableXIV.6NumericaldataforBritishStandard formButtressthreads4 TableX V . 1 . A m e r i c a nStandardol ledhreadso rampas ecrewhel lseforeassembly5 TableX V .2 . A m e ri ca nStandardrolled threadsfo rlampholderscrewshel ls_.5 TableX V I .1 . S y m b o l s,formulas,andbas i canddesign d imens ions ,0.80036AMO..7 TableXVI.2 Limitsofsizeandtolerances,0 . 8 0 0 3 6 A M O7 TableXVI.3.Recommendedag eimensionso rmicroscopebjectivendo">piecethread,0 . 8 0 0 3 6 A M O9 TableVI.4.Limitsfiz eo rheritishicroscopebjectivendosepiecethread 9 TableVII.1.Limitsfize,olerances,ndl lowances;urveyingnstrumentmountingthreads0 TableXVII.2.Recommendedgagedimensionsfo rsurveyinginstrumentmountingthreads1TableXVIII.1.Limitsfize,olerances,ndengthsfhreadsorttachingmountedlenses tophotographic equipment,class3A/3B UNS-3TableXVIII.2.Limitsofsizendolerancesfo rpreferredttachmenthreadsfo rlens accessories ,36 tpi,class 2,N S4 TableXVIII.3.Limitsofsizeandtolerancesfo rsecondaryttachmentthreadsfo r

lens accessories,36 tpi,class 2,NS4 TableXIX.1.Basicd imens ions of6 0 stub threads 6 Table10.1Standardwrench open ings 7 Table1 1 . 1 . L i m i ts o f size,externalthreads,class50 Table1 1 .2 . L i m i t sof size,internalthreads,class5 0 Table11 .3 . Inte r fe rences ,lengthsof engagement,andtorques,class51 Table13 . 1 . Wiresizes andconstants,single-startA c m e andStub-Acme threads (29 ) .4 Table3 .2 . V a l u e so rwiremeasurementsfingle-starttandardcm ehreads(29)---. 5 Table3 . 3 . V a l u e sorir eeasurementsfingle-starttandardtubcm ethreads(29 )6 Table13 . 4 . V a l u e s of(1 + cosec a')fo ro=1 4 3 0 'andleadangles from 0 to5 .6 Table3 . 5 . Bes ti reiametersndonstantsorargeeadngles ,-in.xialpitchA c m e andStub A c m e threads (29 )7 Table13 . 6 . Wire sizes andconstants,single-start Buttressthreads( 7 ,45 )0 Table14 . 1 . I SO metricscrewthreadsfo rgeneraluse,0 .25 to 300 m m diameter3Table4 .2 .ISOmetriccrewhreadso rcrews,olts ,nduts,.25o9m m diameter5


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FiguresPageFigureXII.1.GeneralpurposeAcmethreadformFigureXII.2.CentralizingA c m ethreadformFigureXII.3.Illustrationo fallowances, tolerances,ndrestlearances,eneralpurpose cm ehreads,lassesG,G,ndG 2FigureXII.4.Illustrationofal lowances,tolerances,an d crestclearances,centralizingA c m ethreads,lasses2C,C,nd4C _5 FigureXII.5.Illustrationfal lowances,olerances,ndrestlearances,entral-

iz ingA c m ethreads,lasses5 Cand6 . C_6 FigureXIII.1.StandardStub cm eo rmfhread 0 FigureXIII.2.Illustrationfal lowances,olerances,ndrestlearancesorStubA c m ethreads 4 FigureXIII.3.ModifiedForm StubA c m ethreadwithbasicheighto f0 . 3 7 5pitch.5 FigureXIII.4.ModifiedForm2StubA c m ethreadwith basicheighto f0 .25pitch..5 FigureXIV.1.FormofButtressthreadhaving7 ressureflanknd4 5 learanceflank9 FigureXIV.2.Illustrationo ftolerances,l lowances,ndroottruncations,Buttressthreads 1 FigureIV.3.Britishtandardo rmfButtressh'a d4 FigureV . 1.Illustration of threadorm , allowance, an d tolerances, Amer icanStandardrolled threadsfo rscrewshel lso felectriclampholdersandlampbases. 5 FigureX V I . 1 . Typicalrrangementfmicroscopebjectivendosepiece6 FigureXVI.2.Dispositiono ftolerances ,al lowances,an dcrestclearancesfo r0 .80 0 3 6 A M Othread8 FigureXVI.3 Basicformo fWh i t worththread 9 FigureXVII.1.Surveyinginstrumenttripodheadan dbaseplate0 FigureXVIII.1Tripodscrew,4 2 0U N O 1 A 1 FigureXVIII.2.Tripodsocketincamera,Yt20UNC--1B1FigureXVIII.3 Spacerfo ruseontripodwith0 .3 4 0in .lengthscrew,^20UNCIB2 FigureXVIII.4Tripodscrew,H 1 6UNC1A 2FigureXVIII.5 Tripodsocketincamera,%l6UNCIB2FigureVIII.6 Adapter;16N C 1 Axternalhread,i 2 0UNCIBinternalthread 2FigureVIII.7.Length,i lot ,ndndercutfttachmenthreadso rensc- cessories 4 FigureXVIII.8.Shuttercablereleasetipwithtaper(European)thread( 5 U tpi)5 FigureXVIII.9.Threadetailsforshuttercableeleaseipandocketwithaper(European)hread5 0pi )5 FigureXVIII.10.ShuttercablereleasetipwithstraightAmer ican )hread5 FigureXVIII.11.OpentypeshuttercablesocketwithstraightAmer ican )hread..5 FigureXIX.1.Modifiedquarehread1 0 ncludedngle)asicroportions6 Figure1.1.Illustrationsho w i n gmaximumndminimumnterferences,lassthreads 9 Figure2.1 . Erfectiveengthpplicablenlongationormula.3Figure2.2 . Dr i ll i ngfo relongationdeterminationw h eno neendisnotaccessible..3 Figure3 .1 . Basiso fleadanglecorrectionforexternalthread9 Figure3 .2 . Diameters o f "best" and "maximum" thread wiresor Buttressthreads. 0 Tigure4 .1 .ISO basicprofilefo rinch andmetricscrew threads1 Figure4 .2 .ISOesignrofileo fxternalndnternalhreadswithnl lowance forinchandmetricscrewthreads2Figure4 .3 . ISO designprofileofexternalandinternalthreadswithoutanallowance forinchandmetricscrewthreads2V I


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1957H A N D B O O KO FSCREW-THREADSTAND-ARDSFO RFEDERALSERVICES,PARTIIA sApproved960

SECTIONXII.ACMETHREADS11. GENERALANDH ISTO R ICAL

Whenormulatedrioro8 9 5 ,Acmehreadswerentendedoeplacequarehreadsndvarietyofhreadsofotherformsusedhieflyortheurposefroducingraversingmotionsnmachines,ools,tc.cmehreadsrcowextensivelyusedor varietyofurposes.hissectionrovidesorwoeneralpplicationsfAcmehreads,amely,eneralurposendcentralizing.2Thehreelassesfeneralurposehreadshaveclearancesonalldiametersfor freemovementandmayeusednssemblieswithhenternalthreadrigidlyfixedandmovementoftheexternalthreadn irectionerpendicularotsxislimitedytsearingrearings.heive classesfentralizinghreadsave imitedclearancethemajoriametersfhexternaland internalthreads,so thatabearingatthemajordiametermaintainsapproximatelinementofthethreadxisndreventswedgingnhelanksofhehread.ornyombinationfhefiveclassesofthreadscoveredinhissectionsomeendplayorbacklashwillresult.hisis unavoid-ableforinterchangeableproduct.henbacklashorndlaysbjectionable,omeechanicalmeanshoulderovidedoliminateheon-dition.heollowingracticesaveeensuccessfullyused:(a)henternallyhreadedembersplitparallelwiththeaxisandadjustedandlappedofitheexternallythreadedmember;(6 )henternallyhreadedmembersappedfirstandtheexternallythreadedmemberismilled,ground,orotherwisemachinedtof ittheinternallythreadedmember;(c)henternallyhreadedembersplitperpendicularohexis,ndhewoartsreadjustedoearonoppositelanksofthehreadofhexternallyhreadedmember.Inanycase,ufficientendplaymustbelefttoprovideacloserunningfit.IndditionoimitsfizeorhetandardseriesfiametersnditchesfAcmehreads,tablesfitchiameterohrancesrovideorawidehoicefiametersor iventandardpitch,ndysefheormulasoriameterand pitchincrementsshownintablesXII.6,XII.7,andXII.8,pp.7 ,8,and9 ,thepitchiametertol-

1ThissectionIs In substantialagreementwithAmericanStandardsAssoci-ationpublicationA SA B1.5 ,"AcmeScrewThreads,"whichIspublishedbytheA9ME,29W.38thSt.,N ew YorkIS.N.Y.helatestrevisionshouldbeconsultedwhenreferringtothisA SA do ment.1StubAcmethreadsar ecovered In sectionXIII,p.18 .

ancesforspecialdiametersandpitchesanede-terminedorac hlass.ormulasndataorusewithspecialthreadsarels oprovidedinableXII.5,.,oritchiameterllowancesnexternalhreads,ndnableXII.4,.,ormajorndinoriameterllowancesndtolerances.Multiplehreadshouldeonsideredhenfastrelativemotionisrequired.Whilethreadsforvalveoperationmayb emadetothisstandard,thisapplicationishighlyspecial-izedndheseatahouldoteusedwithoutconsultationwithhealvemanufacturer.

2.SPECIFICATIONSO RC M E F O R MO FTHREAD1 .NGLEOFTHREAD.Thenglebetweenheflanksfhehreadmeasurednnxiallaneshalle9.heineisectinghis9 ngleshallbeperpendiculartotheaxisofthethread.2.ITCHOFTHREAD.Thepitchofahreadis thedistance,measuredparalleltoitsaxis,betweencorrespondingpointsonadjacenthreadforms.3 .EIGHTOFTHREAD.Thebasic heightofthethreadshallb eequaltoone-halfofthepitch.4.HICKNESSOFTHREAD.Thebasicthicknessofhehreadt iametermalleryne-halftheitchhanheasicmajoriametershalle equalone-halffheitch.5 .LLOWANCEMINIMUMLEARANCE)TMAJORN DINORIAMETERS.(a)enera lpurposehreads.Aminimumiametricallear-ancesrovidedtheinoriameterfllexternalhreadsystablishingheaximumminoriameter.020n .e lowheasicinordiameterfor1 0threadsperinchtpi)andcoarser,and0.010in.forfinerpitches.Aminimumiametricalclearancethemajordiameterisobtainedbyestablishingtheminimummajoriameterfhenternalhread.020n.aboveheasicmajoriameteror0pindcoarser,and0.010in.forfinerpitches.(6 )entralizinghreads.Ainimumia-metricallearancesrovidedtheinordiameterofallexternalthreadsbyestablishingthemaximumminordiameter0 . 0 2 0in.be lowthebasicminordiameterfor0pindcoarser,nd.010in.orineritches.inimumiametricalclearanceorheilletsrovidedtheinordiameterystablishingheinimuminordiameteroftheinternalthreadO.lpgreaterhanthebasicminordiameter.Aminimumiametricalclearanceatthemajordip.ueterisobtainedbyestablishingthe minimummajoriameterfhenternalhread.OOlVZ?

abovethebasicmajordiameter.


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6 .H AMF E RSNDILLETS.(a)eneralur -posehreads. Externalhreadsayav eh e crestornershamferedtnnglef4 5 with th exi so maximumepthof0 .0667p .h iscorrespondsoamaximum widthofchamfe rflato f0 .0945p .(b )entralizinghreads.Externalhreadsshal lhaveth ecrestcornerschamferedatanangleo f4 5 with th eaxistoam in im u mdeptho f0 . 05^an d maximumepthf. 0667p .h isorre-spondso m i n i m umwidthfhamfe rla tf0 . 0 7 0 7 pan damaximumwidtho f0 .0945p .SeetableXII.2,cols.6an d7 .) Externalhreadso rlassesC,C,n dCmayhave afilletatth e m in o rdiameternotgreaterthanO.lpan dfo rclasses5 Cand6 Cth em i n i m um filletshal lbe0 .07p ,an dth emaximum fillet0.1/>.Internalthreadsofal lclassesm ayhaveafilletath eajoriameterotreaterhan. 06p .7 .ASICIMENSIONS.(


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TABLEXII.2Basicdimensions,centralizingAcmethreads

Threadsper Pitch,p Heightofthreadbasic),A=0.5pTotaleightofthread(allexternalthreads)A,=ft+0.5allowance*

Threadthick-ness(basic),i=0.5p

4 5 chamfercrestofcentral-isingexternalthreads Maxfilletradius,rootofcentralizingtappedole,0.00pFilletradiusatminordiameterofcentralizingscrews

inch,r. Minepth,0.05;; MlnwidthofchamferHat,0.0707p Minclasses5and6only),0.07p Maxallclasses).0.10p1 2 3 4 5 0

in.0.0044.0050.0060.(170. ( K I O O .0120.0140.0180.0240.0280.0350.0470.0530.0710

8 9 10

16in.0.06250.07143.08333.10000.12500.1 6 6 6 7 .20000.25000.33333.40000.60000.6 6 0 6 7 .750001.00000 in.0.03125. 03 571 .04167.06000.06250.08333.10000.'2500.16667.20000.25000.33333.37500.50000 in.0.0362.0407.0467.0600.0725.0933.1100.1360.1 7 6 7 .2100.2600.3433.3850.5100 in,0.(0125. 03 571 .04167.05000.66250.08333.10000.12500.1 6 6 6 7 .20000.25 0 0 0 .33333.37500.5 0 0 0 0 in.0.0031.0 0 3 0 .0042.0050.0O02.0083.0100.0125.0167.02 00 .0260.0330."380,0500 in.0.0040.0040.0050.0080.0075.0100.0120.0150.0200.0240.0300.0400.0450.0600 in.0.0044.0050.0058.0 0 7 0 .0088.0117.0140.0175.0233.02 8 0 .0350.0467.0 5 2 5 .0700 in.0.006214. 0 0 7 1 12.008310.0100g.01256.01675.02004.0 25 0 3.03332H.0-:O0 2.0500m .06671 1 4.07501.1000'Fo rallowance,sec tableXII.4,col.3.

FIOIREXII.2.CentralizingAcmeth-eadform.NOTATION2a-29a=1430'p-pitchn=numlxrof threadsper InchA7-numberof turnsper Inch = basicheightof thread-0.5p(-thicknessof thread0.5 pF.-0J707p-basicwidthof flatof crestof InternalthreadF,,0.3707p-baslcwidthof flatof crestof externalthreadF,0.3707p-0.25X(maJor-di9rueterallowanceon internalthread)Fr."=0.3707p-0.2X(minor-diameter llowancenxternalthreadpitch-diameterallowanceonexternalthread).Fm an dF, .aremeasured fromthe intersectionsof the straightflanksan droots.


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(b )pecialequi r emen tsdevia t ionsfromomi-naldiameter).Applicationsrequiringspecialma-chiningrocessesesultingn asiciameterotherhanhenominaliametersshownnableXII.3,olumn,hallhavellowancesandtoler-ancesinaccordancewithableXII.4,ootnotea;tableII.5;ndabulatedolerances,ablesXII.6,XII.7,andXII.8.(c)peciali ame t e r s .SpecialiametersotshownnableXII.3ornotdivisibleye,shallshowheactualbasicmajordiameterinecimalsondrawings,specifications,andtools.

3.TANDARDACMETHREADERIES3Therehaseenelected criesfiametersandssociateditchesfAcmehreadsistedn tableXII.3hichsecommendedsreferred.

'WhenAcmecentralizingthreadsareproducedinsingleunitsorI n erysmallquantities(andprincipallyinsizes larger thantherangeof commercialtapsand dies)wherethemanufacturingprocessemployscutting tools(suchaslathecutting),Itmayheeconomicallyadvantageousnndthereforedesir-ableto havethe centralizingcontrolof thematingthreadslocatedatthe minordiameters.Particularlyunderthebove-mentionedyp eofmanufacturing,hed- vantagescitedforminordiameter centralizingcontrolovercentralizingcon-trolatthemajordiametersof thematingthreadsare:(1)Orcatereasean dfasterchecking of machinedthreaddimensions.tIsmucheasier to measure theminordiameter (root)of theexternalthreadan dthematingminordiameter(crestorbore)of the internalthreadthanitisto determinethemajordiameterroot) fthenternalthreadan dhemajordiameter(crestor turn)of the externalthread;(2)bettermanufacturingcontrolofthemachined sizedu etogreatereaseof checking;(3)owermanufacturingcosts.

Theseiametersnditcheshaveeenarefullyselectedomeetheresenteedswithheew-estnumberofitems,nordertoreducetoamini-mumtheinventoryofbothoolsandgages.4.LASSIFICATION AND TOLERANCES, ACMETHREADS

ThererestablishedereinhreelassesfthreadsoreneralurposendivelassesorcentralizingAcmehreads,asfollows:Typeo rthread Classof thread

Generalpurpose2()2C 303C 404C 1 Centralizing C J 6CTheselasses,ogetherwithheccompanyingspecifications,reorheurposeofassuringheinterchangeableanufacturefcmehreadedparts.achuserisfreeoelectheclassesestadaptedoisarticulareeds.tsuggestedthatexternalandinternalthreadsofthe sameclassb esedogetherorithereneralurposercentralizingssemblies.fessacklashrndplaythanrovidedyclass2sdesired,classes3 and rerovidedorotheneralurposendcentralizinghreads,ndlassesCndCorcentralizingthreadsonly.

TABLEXII.3A ernehreadseries,basic diametersandthreaddataIdentification Basic diameters Threaddata

Oeneralpurpose,all Centralizing,classes Leadangleatbasicclasses,andcentralizing, > C and6C pitchdiameterclasses2C,3C,and4C Thread Basic Basic (leneralom i -na l Threads thick- height width purpose, Shear Stresssizes per Pitch, nessat of of flat, all Central- area, area.(all Inch,n Pitch Minor Major Pitch Minor P pitch thread, F= classes. izing class classclasses) Major diam- diam- diam- diam- diam- line, n=0.5p 0.3707p andcell classes 30 301>diameter,E- eter,K= eter,t eter,K= eter,K= I=0.5p tralbing 5Candeter,D ( />-) (D-2h) (73-0.025

V-)(/ Figuresgivenare tbe minimumstressareabasedon themean of th eminimum minoran dpitchdiametersof;lieexternalthread.


12/74

A lllassesfeneralurposexternalndn-ternalthreadsmaybeusedinterchangeably.herequirementforaentralizingfi tshatheumofhemajor-diameterolerancelushemajor-diameterallowance ontheinternalthread,andthemajor-diameterolerancenhexternalhread,shallequalorbelessthanthepitch-diameterallow-anceonheexternalhread.class2Cxternalthread,whichhas largeritchiameterllow-ancethaneitheraclass3CorACexternalthread,caneusedinterchangeablywithlasses20,3C,or 4Cinternalthreadsandfulfil lthisrequirement.Similarly, class3 CxternalhreadaneusedinterchangeablywithlassesCrCnternalthreads,utonly lass4Cnternalhreadanbeusedwithaclass4Cexternalhread.lasses5CndCxternalndnternalhreadsane usednterchangeably.heverageacklashoranycrosscombinationwillb ebetweenthevaluesforbacklashwhenbothmembersareclass5 Candwhenbothmembersareclass6C.1 .ASICIAMETERS.Theaximumajordiameterfhexternalhreadsasicnds

theominalmajordiameterforalllassesxceptclasses5Cand6C.hemaximummajordiameterofallclass5 Cand6 Cexternalthreadsisthebasicmajoriameter,,stablishedyubtracting0.025^1)romheominaliameter,.heminimumitchiameterfhenternalhreadisbasicforallclassesandequaltothebasicmajordiameterminusheasicepthfhread,Q.op.Theasicminoriametersqualoheasicmajoriameterinuswiceheasichreaddepth,.heminimumminoriameterfhegeneralurposenternalhreadsasic.heminimumminoriameterfheentralizingn-ternalthreadisO.lpabovebasic.2.ENGTHFNGAGEMENT.Theolerancesspecifiedereinrepplicableoengthsfn-gagementotxceedingwiceheominalmajordiameter.3 .OLERANCES.(a)heolerancespecifiedrepresenthextremeariationsllowednheproduct.heyreuchsoroducenter-changeabilityandmaintainahighgradefrod-uct.

TABLEXII.4.To lerancesandallowancesminimumlearances)formajoran dminor iameters .cmehreadser iesm ax majordiametero fexternaltw" ,basic. Basithreadheight,/i=0.5p.)

Threadsperinch,B>

Allowances frombasicmajorandminordiameters,allclassesToleranceonminordium,allinternalthreads,plus0.05p

Toleranceonmajordiameter,plusoninternal,minusonexternalthreads

Allexter-nalthreads Internalthread GeneralPurpose Centralizing Size

Minordiameter,minus

Generalpurpose Centralizing Allclasses Class2C Classes3CandC Classes4Cand6C

External'thread,O.llpInternalthread

ExternalandInternalthreads,0.0035VT>

Externalthread,tUMbs/T)

Internalthread,0.0035V7>

Externalthread,0.0010V75

Majordiameter,plus Majordiameter,'1plus

0.imw\/T)

Minordiameter,'plusO.lp

Internalthread,0.0020V7>

1 2 3 4 S 7 8 9 10 1 1 12 13 14 in .MHi .- 16 14 12 12 10

86 SS5 444433322 22 2

in.0.010.010.010.010.020.020.0211.!.2-i.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020

in.0.010.010.010.010.020.020.020.020.020.020.020.020.020.020.020.020.020,020.0211.020.020.(1.020

in. in. in.0.0050.0050.0050.(150.0050.0002.0083.008;).0100.0100.0100 0125 .0125.0125.0125.0107.017 .0107.0250.025.0250 .0250 .0250

in.0.0050.0050.0050.0050.0050.0062.0083.0083.0100.0100.0100.0125.0125.0125.0125.0107 .0107 .0167 .0250.0250.0250.0250.0240

i.0.010.010.010.010.020.020.020.020.020.020.020.02(1.020.020.020.1120.020.020.020.020.020.020.020

in. in. in. in. in.M 7A .0007

.0008.0009.0000.0010

.0011 .(Kill.0012.0012

.0013.0014.001.001.0017

.0017.001.mwi.0021.0022

6.0100.0125.0107.0107.0200.0200.0200.0250.0250.0250.0250 .0333.0333.0333.0500.ll.Vll.05110 .0500.0500

0.0007.0008.000.0110.0010 .0011 .0011 .0012.0012.0013.0014.01115.001.0017.0017.001 .0020.0021 .0022

MHHHl1Mm1H-....l22M2H-2M33M4 4M8 .0025.0028.0030.0033.0035.0037.003.0041.0043.004.004.0052.0055 .0058.0001.0068.(XI70.0074 .0078 0.0011.0012.0013.0014.0015.001.0017.0018.0018.0020.0021.0022.0024.0025.002.0028 .0031).0032.0034 0.0025.01)28 .0 1 ) 3 ( 1 .0033.0035.0037.003.0041.0043.004.004.0052.0055.0058.0061.0065 .01170.0074 .0078 0.0014.0016.0017.001.0020.0021.0022.0023.0024.0026.0028.0030.0032.0033.0035.0037.0040.0042.0045

Valuesforintermediatediametersshouldbecalculatedfromth eformulasincolumnheadings,bu tordinarilyma ybeinterpolated. > Intermediatepitchestakethevaluesofthenextcoarserpitchlisted.Valuesare 0.020in .ford tp ian dcoarser,an d0.010in .forfinerpitches.4Th eminimum clearanceatthemajordiameterbetweenth einternalan dexternalthreadisequalto col.5 . Th eminimum clearanceatthe minordiameterbetweenthecentralizinginternalaixlexternalthreadisthesu mofthe valuesin eo!s.3and6.'To avoid acomplicated formulaan dstillprovide anadequate tolerance,th epitchfactor Isusedas abase,withtheminimumtolerancevaluese tat 0.005 in .NOTE.Themaximumngularplayofaentralizinginternalhread,nediameterong,ntsexternalhreadorhemaximummajordiameter clearanceis1 orless.Toleranceonminordiameter of al lexternalthreadsis1.5Xpitclwliamcter tolerance.


13/74

TABLEXII..Pitch-diameterallowancesfor AcmehreadsNominalsizerange* Pitch-diameter allowancesonexternal"threads,generalpurposeandcentralizing

Above Toand including Classes20,2C,and5C;0 . 0 0 8 V/>

Classes30,3C,and6C;0.006V/)

Classes40and4C;0 . 0 0 4V*

1 2 3 4 5in.0

M Min. M M' / ! 9 1 'MeW. Mo IMIMoIMl?i191 m2H2H2H2% 33 434MWm

in.0.0024.0040.0049.0057.0053.0069.0075.0080.0085.0089.0094.0098.0105.0113.0120.0126.013 .0140.0150.0160.0170.0181

in.0.0018.0030.0037.0042.0047.0052.0056.0060.0064.0087.0070.( 173.(X)79.0085.0090.0095.0099.0105.0112.0120.0127.0136

in.0.0012.0020.0024M.91 .0028.0032> M--> MM 1 M IM

IMVM-191m2H

.0 0 3 5 .0037.0040.0042.0045

.0047.0049.0 0 5 2 .0057

.00602H2H--.2%m. 3V.0063.006.0070.0075.00804M .0085iH .0091Thevaluesincolumns3,4,and5are tobeusedfo ranysizewithinthecorrespond ingrangesh owninc o lumn s and2 .hesevalues arecalculatedfrom themeanofcolumns and2.tisr ec ommen d edthatthesizesgiven intable XII.3beusedwheneverpossib le . > A nincreaseof10 percentintheallowance isr ec ommen d edfo r eachinch,o rfractionthereof ,thatthelengthof engagementexceedstwodiameters.

(b )heolerancesondiametersofthenternalthreadshalleppliedlusromheminimumsizesoaboveheminimums izes .(c )heolerancesondiametersoftheexternalthreadsshallbeappliedminusfromthemaximumsizestobelowthemaximums izes .(d)heitch-diameteroleranceswhichon-trolhreadhickness)ornxternalornternalthreadofagivenlassarehesame.heitch-diameterolerancesorheroductncludeeadandangledeviations.Pitchdiametertolerancesforallclassesandforvariouspracticablecombinationsofdiameterandpitch,aregivenintablesXII.6,XII.7,andXII.8.Theelativeroportionsfheitchiametertolerancesre:lass2,3.0;lasses nd,.4;andclasses4and6 ,.0 .(e)heolerancesnheajorndinordiametersfhexternalndnternalhreadsareistednableXII.4ndreasednhefollowingformulas,whicharetob eusedfor specialthreads:

4 .LLOWANCESMINIMUMCLEARANCES).Al-lowancesappliedohepitchiameterofhex-ternalhreadorlllasses,eneralurposendcentralizing,reivennableII.5.hesepitchiameterllowancesrcqualoheumofhellowancenmajoriameter,olumn,tableXII4 ,ndhesumftheolerancesonx-ternalndnternalhreads,olumns0o4 ,inclusive,ableXII.4,oreneralurposeridcentralizing,plusanadditionalamounto f0.002v'Z> in.orlasses50nd60.hissheminimumpitchdiameterallowancethatisrequiredtomain-tainhecentralizingfitandminimumendplayof0.0005/0in.o rclasses5Cand6C.Forentralizingits,henheroductaslengthfngagementreaterhanhetandardlengthfhehreadingageshownnableXII.14 ,olumn..7 ,ndeadeviationsotexceedingthevaluesshowntthebottomofthattable,ndwhengo"hreadingagesfheselengthsreoeused,hemaximumitchdiam-eterfhexternalhreadhalleecreasedytheamountshowninableXII.14,column5 .ftheleaddeviationsintheproductaregreaterthanindicated,theallowancefortheringgagestatedincolumnhouldencreasedroportionately.However,if methodsof gagingtheexternalthreadareoesedwhichwilletectngleeviationandcumulativeleaddeviation,thepitchdiameterofhexternalhreadhalleelowheabularmaximumitchiameterfhexternalhreadbynmountufficientoompensateorhemeasureddeviations.A nncreasef0ercentnhellowancesrecommendedorachnch,rractionhereof,thatheengthfngagementxceedswoi-ameters.5 .ORMULASO RIAMETERS.Theormulasforheajor,itch,ndinoriametersregiveninableXII.9.

5.IMITSO FSIZE,C M EHREADSLimitsofsizefo vgeneralpurposeA c m ehreadsofthepreferredseriesofdiametersandpitchesarcfjivennableXII.10. ThepplicationfheseunitsisillustratedinfigureXII.3.LimitsfizeorentralizingA c m ehreadsfthereferrederiesfiametersnditchesregivennablesXII.11ndXII.12.hepplica-tionfheseimitssllustratedniguresXII.4andXII.5.

TolerancesonmajorandminordiametersofexternalandinfernalthreadsTypeofthread Majordiameter Minordiameter

Externalhread Internalthread Externalthread internalthread0.05p(Min-0.905in.)0.0035-/10.020 in . fo r 1 0 tpi an d < coarser;0.010n.oriner1 pitches0 . 0 0 3 5 V # --0.0035 Vw ll.SXpitch diameter toler-| ance ll.SXpitch diameter toler-ance !i.05p(Mln-| 0.005 in.)IClass2COntra!i>.ing{Classes3CndC0.0015Vo.uoioVfl10 .05p (Mtn-| 0.005in.)(Classes4Cand6C0 . 0 0 2 0 V

Toavoidacomplicatedormulaandstillprovideanadequateolerance ,thepitchactorisusedasaase,withheminimumolerancevaluesett0 .005in.


14/74

6.HREADDESIGNATIONSTheollowingbbrev iat ionsreecommended fo ruseondrawingsandinspecifications,an dontoolsan dgages:

ACME=Acmethreads, G=generalpurpose,C=centralizing,LH=left-hand.Exampleso fdesignations:Right-handAcmethreads:

l%~6ACME4C=Centralizing class4 CA c-m ehreads;m a jo riameter%n .,itch0 . 1 667 in. ,single,right-hand.2%OAp0.8L ACME3C=CentralizingclassCcm ehreads;ajoriameter2 %n.,itch.4n.,ead.8n .,ouble ,r ight -hand .2%0.3333p 0 . 6 6 6 7 L ACME5C=Ce n -tralizinglassCcm ehreads;omina lmajordiameterxkn.basicmajori am-eter2 .4605 in . ) ,pitch0.3333in. ,lead 0 . 6 6 6 7 in. ,double ,r ight -hand .1 % ACME2G=Generalurposelass Left-handAcmethreads:1 I1**/ '2G cm ehreads;m a jo riameter%n ., pitch0 .2500in. ,single,r ight -hand .2%0 .4p 0 . 8L A C M E 3 G =G e n era lpur-poselass3G cm ehreads;m a jo rd iam-eter2 % in. ,pitch0 .4 in. ,lead0 .8 in. ,double ,right-hand. A C M E 2 G L H 2% 0 .4p 0 . 8 L A C M E 3 G L H IK6A C M E IC LH27/ 8 0.4p 0 . 8 L A C M E 3 C L H 2& 0.3333p 0 . 6 6 6 7 L A C M E 5 C - -L H

TABLEXII.6.PitchdiametertolerancesforAcmescrewthreads classesSGand2CThreadsper Pitchincrement,0.030 Vl/n

Pitchdiametertolerances fornominaldiametersof: inch,n Min. Mein. Win. Ji in. Win. Win. ?iin. Win. lin. lHin. 1 W in .

16.. in. 0.00750.00802.00866.00946.01061.01225.01342.01500.01732.01897.02121.02449.02598.03000

in .0.0105 in. 0.0109.0114in. 0.0112.0117.0123.0132

in.0.0115.0120.0126.0135

in.0.0117.0123.0129.0137.0148

in. 0.0122.0128.0134.0142.0154

in.0.0127.0132.0139.0147.0158.0174

in. in. in. in.1 4 0.0136.0143.0151

.0162.0179.0190

0.0140.0147.0155.0166.0182.0194

12 0.0150.0158.0170.0186.0108.0214

0.015410 . .01628.. . .01736 .01905.. .02014 .021732M....2IM.... j 1H1Diameterincre-ment,0.006Vx>.. 0.00300 0.00335 0.00367 0.00397 0.00424 0.00474 0.00520 0.00561 0.00600 0.C0636 0.00671Threadsper Pitch increment, 0.030 Vl/

Pitchdiametertolerancesfornominal diameterso f:inch,n IWin. lHin. HMta. 2in. 2n. 2!4n. 2in. 3in. 3Min. 4in. Hiin. 5in.

16in.0.00750.00802.00866.00949.01061.01225.01342.01500.01732.01897.02121.02449.02598.03000

in. in. in. in. in. in. in . in . in. in . in. in.1 412100.0165

.0176.0193.0205.0220

0.0168.0180.0196.0208.0223.0247

0.0174.0185.0202.0214.0229.0253.0239

80.0191.0207.0219.0235.0258.0275.02976 0.0212.0224.0240.0263.0280.03025 0.0229.0245.0268.0285.03074 0.0249.0273.0289.0312 0.0254.0277.0294.0316.0349.0364

0.0262.0285.0302.0324.0357.0372.0412

0.0270.0293.0310.0332.0305.0380.0420

324... 0.0300.0317.0339.0372.0387.0427

0.0307.03242 .0346Hi .03791W .03941 .0434Diameterincre-ment,0.006JT )0.00704 0.00735 0.0079 0.0084 0.00900 0.00949 0.00995 0.01039 0.01122 0.01200 0.01273 0.01342

Th eequivalenttoleranceon thread thicknessis0.259times the pitchdiametertolerance. Fo ran intermediate nominal diameter,applythepitchdiameter toleranceforthenextlargernominaldiameter giveninthistable.No.Thepitchdiametertolerancesshownequalthe sumof thepitchincrementan dthediameter Increment


15/74

TABLEXII.7. i'iUhdiameter olerancesforAcmescrewthreads,classes3G ,3C,and,5CThreadspe r Pitchincrement,

0.014 VvPitchdiametertolerances (o rnominaldiametersof :

i nch ,n Mln. M in . Hin. Jf in . Hin. H n. H n. Jsin. lin. in. IHin.16 14 12in.0.00350.00374.00404.00443

.00495.00572.00626.00700

.00808

.00885.00990

.01143.01212.01400

in.0.0049 in.0.0051.0053in .0.005 2.0055.0058.0061

in.0 05 4.0058 .0059.0063

in.a ms; .0057 .001.0064.0069

in .n 05 7 .0060.0062.0066.0072

in ..0062.0065 .0068.0074.0081

in.0.0064.0067.0070.0076.0083.0089

in.0.0065.0068 .0072.0078.0085.0091

in. 7 7 " ".0074.0079.0087.0092.0100

in..72* 10 .0076

8 .00816 .00885 .00944 .010132W2IMmiDiameterincre-ment,0.0028 V~ 0.00140 0.00157 0.00171 0.00185 0.00198 0.00221 0.00242 0.00262 0.00280 0.00297 0.00313Threadspe r Pitchincrement,0.014 v'l/'i

Pitchdiametertolerancesfor nominaldiametersof i nch ,n 1in. Hiin . Win. 2in . 2'iin . 2Hn.

in.Wi n . 3in. 3in. 4in.

in.44In . 5in .

16in.0.00350.00374.00101.00443.00495.00572.00626.00700.00808.00885.00990

01143.01212.01400

in. in . in . in . in. in . in. in. in. in.14 1 12100.0077.0082.0090.0095.0103 0.0070.0084.0091 .0097.0104

.0115

0.0081.0086.0094.01000107 .0118.0126

; : ; ; 80.00H9.0097.01020110

.0120.0128.0139

60.0099.01040112.0123.0131 .0141

50.0107.0114.0125.0133.0143

4 0.0116.0127.0135 .0145

0.0118.0129.0137 .0147.0163.0170

0.0122.0133.0141.0151 .0167.0174.0192

0.0126.0137 .0145.0155.0170.0177.0196

3 0.0140.0148.0158.0174. 0181.0199

0.01432H .01512 .0162m .01771W. . .0184i .0203Diameterincre-ment,O.OOKVZL 0.00328 0.00343 0.00370 0.00396 0.0042C 0.00443 0.00464 0.00485 0.00524 0.00560 0.00594 0.00626

Theequivalenttoleranceonthreadthicknessis 0.259 timesthepitclidiametertolerance. Foronintermediatenominaldiameter,applythepitchdiametertolerancefo r the nextlargernominaldiametergiven inthistahlc.NOTE.Thepitchdiametertolerancess h o w nequalthesumo fthepitchincrementandthediameterincrement.

8


16/74

TABLEXII.8 ai t ckdiameter olerancesforA cmescrew threads,classt s4G ,C,an d6C Threadsper TMtch increment,0 .010 V V n

Pitchdiametertole rancesfo rnominaldiametersof : inch,n }i n. Me in . %in. %6n. Win. Hin. in. Hin. lin. lHin. 1! 4in.

16 in.0 .00250. 0 0267.00289 . 0 0316 .00354 . 0 0408. 0 0447. 0 0500. 0 0577 . 00632 .00707 .008 :6 . 0 0 M S 6 . O l ' J O O

in .0.0035 in .0.0036 . 0 038in.0.0037.0039.0041.0041

in.0.0038.0040.0042. 11045

in.0.0039.0041.0043.0046.0050

in .0.0041.0042.00450 0 1 7 . 0 0 5 1

in.0.0042.0044.0046.0049.0053.0058

in. in . in . in . . 0 4 5 .0048.0050.0054.0060.0063

.047 . 0 049 . 0052. 0 055 . 0 061. 0 065

12 0 .0050 . 0053 . 0 057. 0062 . 0 066 .0071

0 .0051 10 . 0 054 8 . 0 0586.. . 0 0 635 . 0 067 4 . 0072 3 12 H2IMU s iDiameterincre-

ment,0.002y7>.. 0 .00100 0 .00112 0.00122 0.00132 0.00141 0.00158 0.00173 0.00187 0 .00200 0 .00212 0.00224 Threadsper Pitchincrement,0.010 Vl/n

Pitchdiametertolorunu' fo rnominaldiametersof :Inch,n lHin. lHin. IHin. 2in. 2Mn. 21 4n. min. 3in. 3 V4 i n . 4 in. 4M in. 5 in.

16in.0 .00250 .00267 .00289 . 0 0316. 0 0354. 0 0408. 0 0447 . 0 0500 . 0 0577. 0 0632. 0 0707 . 0 0816. 0 0866. 0 1000

in . In . in . in . in . t o . in. in . in. in . in . in.14 1 210 0 .0055 .0059 .0064 . 0 068 .0073

0 .0056 . 0 060.0065 . 0 069 .0074

0.0058.0062.0067.0071.0076.0084.0090

8 0.0064.0069.0073.0078.0086.0092.0099

6 .0 0 7 * 1 .0075.0080.0088.0093.0101

5 0.0076.0082.0089.0095.0102

4 0.0083.0091.009.0104

.8 5 .00f?.. 0 098. 0 105 .0.16.0121

0 .0087 . 0095 .0101. 0 1 0 8. 0 119 0124 . 0 137

0 .0090 . 0 098 . 0103 . 0 111 . 0 122. 0 127 . 0140

3 0 .0100 . 0106 . 0113 .0124 . 0 129 . 0 142

0 .0102 2M-. . . 0 1082 . . 0115 1M--. . 0 126 1W .0131 1 . 0 145 Diameterincre-

ment,0 .002V# 0.00235 0 .00245 0.00265 0.00283 0.00300 0.00316 0.00332 0 .00346 0 .00374 0 .00400 0 .00424 0 .00447 Theequivalenttoleranceon threadthicknessis 0.259 t ime sthepitchdiametertolerance. Foranintermediatenominaldiameter,applythepitchdiametertolerancefo rthenextlargernominaldiametergiveninthistable.NOTE.Thepitchdiametertolerances s h o w nequalthesu m of thepitchincrementandthediameterincrement.


17/74

TABLEXII.9Formulasfordiameters, AcmethreadclausesClasses2C),30,40Classes2 C,3C,4 C Classes5 C,6 C

l 2 3 EXTERNALTHREADS

Majordla:Basic(max) MinPitchdia:M ax

Min

Minordia:M ax Min

D B-tolfromtableXII.4,cols8,1 0 ,1 1 ,or13

Intinitchiaallow from tableXII.5,o ls3, 4,or 5 Ext m ax pitchdia- to lfrom tablesII.6,II.7,rXII.8Dpallowro mableXII.4,co l3Extm axminordia-1.5Xpitchdiato lfromablesXII.6,XII.7,o r XII.8

fl(D-0.025V 5) B-tolfromtableXII.4, cols 11r1 3

Intinitchia-allowfrom tableXII.5,cols3o r4 Extm ax pitchd iato lfrom tablesXII.7o rXII.8Bp allow from tableXII.4,co l3Extaxinoria-l.SXpitchiaolro mablesXII.7 o rXH .R

INTERNALTHREADSMajordia:

MinM ax Pitch dia:Basicmin ) = M ax Minordia:BasicMin

M ax

D+allowfrom tableXII.4,cols4 o r5 Int m in majordia+tolfrom tableXII.4,cols 9,10,12,o r1 4 fl-O.SpIntminpitchdia+tolfrom tablesII.6,II.7,rXII.8D-pD-pfo rlasses20,30,40)D-p+O.lp( forclasses2C ,3 C, 4 C) Intm in minordia+tol from tableXII.4,co l7

B+allowfromableXII.4,co l5 Intminmajordia+tolfrom tableXII.4,cols12 o r1 4 B-0.5pIntminpitchdia+tolfrom tauXil.7o rXII.8

B-pfl-p+O.lpIntminminordia+tolfrom tableXII.4,co l7

DNominalsizeo rdiameter.B-Basicdiameter(forclasses5 Cand6 C) p-Pitch7.A GESFO RA C M ETHREADS

o ragesepresentingothroductimits ,adequategaginginstrumentsfo rthreadelements ,areecessaryorh eropernspectionfA c m ethreads.h eimens ionsfgo"ndnotgo"gagesshouldbeinaccordancewith th eprinciples:(a)hathemaximum-me ta limitorgo"ag eshouldchecks imul taneous lyas manyelementsas possible,an dthatamin imum-me ta ll imi to r"notgo "hreadag eanffectivelyheckutnee lement;nd6 )hatermissibleariationsn th eageseepti th inh extremeroductl imits . (a)GAGETOLERANCES

Tolerancesfo rth ethreadelementsof"go"an d "noto "hreadageso r cm ehreadsresspecifiedbelow.1 .OL ER A NC ESNITCHIAMETER. T h e pitchdiametertolerancesfo rgagesfo rclasses2G an dCxternaln dnternalhreadsreiven inableII.13,o lumn,ndorageso rclasses3G,3C,4 G,4 C,5 C,an d6 Cexternalan d internalthreadsin tableXII.13,column3.

2.OL ER A NC ESNMAJORNDMINORDIAM-ETERS. T h emajoran dm i n o rdiametertolerances fo rAcmehreadgagesaregivennableXII.13, column4 .3.OL ER A NC ESNE A D . T h eariationn leadofall cm ehreadgagesfo rclasses,,,and6 product shal lno texceed0 .0002inch between anytw othreadsnotfartherapartthanoneinch .However,h eumula t iverrorneadhal lotexceed. 0 003n.orgageswith engthverto n.,nclusive;o r0 .0004n.o rgageswithlengthover3to5in.,inclusive;o r0 . 0006in .fo rfgeswith engthver o0n.,nclusive,o rgagesfo rclass2product,. 0001n.hal le addedtotheabovevalues.ormultiplethreads, th eumulativetolerancefo rpitchandleadshal lb emultipl iedby1.5 .4 .OL ER A NC ESNN GL EFH R E A D .Thetolerancesonangleofthread,asspecifiedintableXII.13,o lumn,o rh eariousi tchesre tolerancesnne-halfh encludedngle.h isinsureshath eisectorfh encludednglewilleerpendicularohexi sfh ehreadwith inroperimi ts .h equivalenteviation from th etruethreadform causedbysuchirregu-laritiessonvexroncaveidesfhread,rs l igh tprojectionsonh ehreadform,houldotexceedth etolerances permittedonangleofthread.

( b ) GAGES FOR EXTERNAL THREADS1.Go"H R E A DINGRHREADNAPGAGE. (a)Major diameter. T h emajordiameterofth e"go"threadringo rthreadsnapgageshal lclearadiametergreaterbv0.01in .thanth emaxi-m um majordiametero fth eexternalthread.(6 ) i tchiameter. T h eitchiameterhal lfi th emaximum-meta lim i threadettingpluggige.(c)Minoriameter.Foreneralurposex-ternalhreads ,hem i no riameterfh ego"threadring gage shal lbeth esameas th e maximum m i no rdiametero fth eexternalhreadplus0 .005 in .fo rpitchesf inerthan10tpi,an dplus0 . 010in .for0tp iandcoarser,oallowfo rpossibledevi-ationsnoncentr ici tyfh eitchn di no rdiameterso fth eproduct.h etoleranceshal lbe appliedminus .F o rentralizingxternalhreads ,h ei no rdiameterfh ego"hreadingagehal lelessh anh ei nunuminoriameterfh e internalhreadyh emountfh el lowance onitchiameter ,ableXII.5,o lumns o.Th etolerance(table XII.13,col.4 )shallb e applied minus .(d)LengthTheengthfhego"hreadringo rthreadsnapgageshouldapproximateh e lengthfngagementse eootno teoable XII.14)butshould notexceedthelength specifiedintableXII.14,col.3. 2.MAXIMUM-METALIMITH R E A DETTING PLUGORGO"H R E A DRINGORS N A PGAGE S. (a)Majordiameter. T h emajoriameterofh e basic-crestmaximum-meta lim i threadetting

10


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INTERNAL THREAD (NUT)0.0945>>MAX

EXTERNAL THREAD (SCREW)FIGUREII.3.Illustrationfallowances,olerances,ndrestlearances,general"purposeAcmethreads,classes2G ,G,and4G .NOTATION p-pltch,k~lisicthreadheight.HeavyHoesshowbasicsice.

plugagehalleheamesheaximummajordiametero ftheexternalthread.hegagetolerance(tableXII.13,col. 4 )shallb e appliedplus.Themajoriameterfheruncatedmaximum-metalimithreadettinglugagehallesmalleryne-thirdfheasichreadepth(=p/6)hanheaximumajoriameterfthexternalhread.heageolerancetableXII.13,col .4 )shallb eappliedminus.(b )itchdiameter.Theitchiameterofhemaximum-metalimithreadettinglugorllexternalthreadsshallbethesameasthemaximumpitchdiameteroftheexternalhread.owever,ifheroductlengthofengagementxceedshelengthfheingage,ableXII.14,olumn,theitchiameterfhemaximum-metalimitthreadsettingplugshallb elessthanthemaximumpitchiameterfhexternalhreadyheamounttatednableXII.14,olumn.hegagetolerance(tableXH.13,col.2and3)shallbe

appliedminus.(c )Minord iame te r .Theminordiametershallbelearedelowheminimumminoriameterofthego"threadringgage.(d)en(h.Thelengthofthemaximum-metallimitthreadsettingpluggageshouldapproximatethelengtho fthe"go"hreadringorthreadsnapgage.3 .Go"LAININGRNAPAGEORMAJORIAMETER.Theiameterfhego"plaininggage,rgagingdimensionofthego"plainnapage,halleheameshemaxi-mumajoriameterfhexternalhread.Thelass olerancesgivennootnoteftableXII.13shallbeapplicabletogagesforcentralizingthreads.olerancesivennableII.13,column4 ,hallb epplicableogagesforgeneralpurposethreads.heolerancesshalleppliedminus.

4 .NOT GO" THREAD RING OR THREAD12


20/74

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21/74

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22/74

INTERNAL THREAD (NUT)0.0945P AX 0.0707pM IN

~" /445 - "* M i0.067P AX 0.050PM IN

DETAIL OF CHAMFER

BASICHICKNESSF THREAD t=0.5p

ct 5*

EXTERNAL THREAD ( SCREW)FIGUREXII.4.Illustration fallowances,olerances,ndcres tclearances,entral iz ingAcmethreads,lassesSC ,C,nd4C .

NOTATIONp=pitcht=busicthreadheight.Heavyl inessh ow bas icsize.S N A PAGE. (a)ajoriameter. T h eajordiameterfhenoto "hreadingrhreadsnapag eshal llear iametergreaterby0.01 in .hanheaximumajoriameterfheexternalhread.helearanceutayav e 0 .435paximumidthetweenntersectionswiththeflanksofthehread.(6 ) i tchiameter. T h eitchiameterhal lfi th emin imum-me ta ll imi threadettinglu ggage.(c)Minordiameter. T h em in o rdiametershal lbeheasicinoriameterfhenternalthreadplus p/4,with th eolerancetableXII.13,

col.)ppliedlus.fth ealueo rm i n i m um m i n o riametere terminedyh eormulasgreaterhanhei n imumitchiameterfth eexternalthread,themin imum m i n o rdiametero fh eagehal lepecifiedshei n imum pitchiameterfh externalhread.( r f )engthTh eengthfhenoto"threadingo rthreadnapag ehouldpproxi-mate i tchesse eootno teoableXII.14 ) .W h e namultiplethreadisinvolved,the"notgo " threadingo rsnapag eshal lefsuchength asto provideatleast ullturno fthread.5 .HREAD ETTING PLUG FOR "NOTGO"

1 5


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INTERNAL THREAD (NUT)

* U) u Q: it jt < * o ( f c 4< * Ui c s a . 5O *5 VI E C ^ Q4 1 I \o o Ui rv Uj

fILL ET R/OIUSO.IOPAX 0.07p IN

EXTERNAL THREAD ( SCREW)FIGUREXII.5.Illustrationofallowances,olerances,andcrestclearances,centralizingAcmethreads,classesSCand6C.

N O T AT IO N rendheightHeavyl inessh owbas icform.

p=pitchbasicthreadheight

THREADINGRH R E A DN A PAGE. (a) Major diameter. T h emajo rdiameter o fth ebasic-crestin imum-metalim i threadettinglu ggagehalleh eam esh emaximummajordiametero fth eexternalthread.h egagetoler-ancetableXII.13,ol.)halleappliedlus.Themajordiametero fh eruncatedm i n i m u m -metalim i threadettinglu gag ehal le truncatedne-th irdasichreadepth=p/6)smallerthanth emaximum majordiametero fthe16 external thread. The gage tolerance (tableXII.13,o l.)halleppliedminus .(6 )i tchiameter. T h eitchiameterhallbeh eam eshemin imumitchiameterfthexternalhread,i thheolerancepplied plus.(c)Minordiameter. T h em i n o rdiametershal lb elearedelowhemin imumi no riametero fh enoto "hreadingage.(d ) ength. T h elength shal lbeatleastequal


24/74

tothelengthofthe"notgo"threadringorthreadsnapgage.6 .NOTGo"LAINNAPAGEORMAJORDIAMETER.Theagingimensionfhenotgo"lainnapagehalleheamesheminimummajoriameterfthexternalhread.ClassZ tolerances giveninfootnoteo ftableXII.13shall beapplicable to gagesforcentralizingthreads.TolerancesivennableXII.13,olumn4 ,shallbeapplicabletogagesforgeneralpurposethreads.Theageolerancehalleppliedlus.(c)GAGESORNTERNALTHREADS1 .Go"HREADLUGAOE,ENERALUR-POSETHREADS.- (a)Majordiameter.Themajordiametero fthego"threadpluggageforgeneralpurposehreadshallequaloheminimummajoriameterfhenternalhreadinus0.005n.orpitchesfinerthan0pi,ndminus0.010n.or0pindoarser,olloworpossibleeviationsnoncentricityfheitchandmajoriametersfheroduct.heagetolerancetableXII.13,o l.)halleppliedplus.

TABLEII.13.Tolerancesorgo"ndnoto"hreadandplaingages,AcmehreadsToleranceonpitch*diameter Tolerance onmajorandminordiameters

ToleranceThreadsperinch Classes20and 2C

Classes30,3C,40,4C,5C,and 6C

onhalfangleofthread

1 2 3 4 5

1 614In.0.0006.01X16.0006.0007.0008.0009.0010.0011.0013.0014.0015.0018.0018. 0 021

in.0.0005.0005.0006.0006.0007.0007.0008.0008.0008.0009.0010.0010.0010.0010

in.0.001.001.001.002.002.002.002.002.002.002.002.002.002.002

>T he sepitchdiametertolerances fo rthreadQaqtsar enotcumulative;thatis ,theydo notincludetolerancesonload andon halfangle.eadtolerances ar egivenin par.7 (a)3,p.1 0 . T he setolerancesar eapplicableto al lgagesexceptthe"go"and"notgo"threadlugagesfo rmajordiameterfal llassesofcentralizingnternalthreads,andfo r"go"and"notgo"plainringo rsnapgagesfo rmajo rdiametero f centralizingexternalthreads.o rthesegagesthetolerancesrelassZ ,as follows:

Sizerange ClassZ toleranceAbove Toand includingin. in. in.0.029 0.825 0.000100.825 1.510 .000121.510 21 0 .000162.510 4.510 .000204.510 6.510 .00025

(b )itchiameter.Theitchiameterhallbequaloheminimumbasic)itchiameterofhenternalhreadithheolerancetableXII.13,o l. nd)ppliedlus.(c )Minor iameter .-Theminoriameterhallclearadiameterlessby0 . 01in.thantheminimumminoriameterfhenternalhread.{d)ength.Theengthfhego"hreadplugagehouldpproximateheengthfengagementsecootnoteoableXII.14 )utshallnotexceedwicethenominalmajordiameterunlesspecificallyequested.2.Go"HREADLUGAGE,ENTRALIZINGTHREADS.(a)Majoriame te r .Themajori-ametero fthego"hreadpluggageforcentraliz-inghreadshalleheamesheminimumTABLEII.14.Pitchiameterompensationordjustedlengthsof"go"inggages fo)eneialpurposeandcentral-izingthreads

Nominalmajordiameterofexternalthread Lengthf"go"ring

gage

Maximumamount2 diameterslengthofengagementexceedslengthofgage

Maximumamountpitchdiameterof

Above Toand including

"go"ringshallbelessthanmaxi-mum itchdiameterofexternalthread

1 2 3 4 5 in.0in.1 1 W 14m m m 22425 4

2H34 5

2diame-ters.2in2in2n2 12In2ln2* 4n21 4in2Win3in3in:tinin.0M H% 1 m 22 23 35 7 in.0 1 0.0012n*.0012Hi.0015i% .0015m.0015\U.00192 .00192'i .. .001921 4 .00192?i.00193.00274.0039NOTE.Theboveompensationsasedn engthfengagementno lxceedingwoiametersnd aea deviationn the productotexceedingheollowingaluesinn c h ) :0 .0003Inlengthof 4 in .o rless..0004in lengthoverHtoHiin ..0005in lengthoverH4 to 3 In ..0007in lengthover3to6in ..0010in lengthover6to1 0in .Theprincipleshaveee nestablishedintheforegoingrequirementsthat"go"ageshouldpproximateheengthfngagement,ndnoto " gagesshouldK'hreepitchesong.orreasonsof e conomyrlimitationsingagemanufactureo ruse,tmaybedesirabletomodi fyhe seprinciplesto :1)Takeadvantageoftheeconomiesof usingstandardblanks,aslistedin thelatestissue of CS8,OageItlanks,wherevertheymayb e utilizedsuccess-fully.2)voidto oc umber someringgagesaswel las excessivelyexpensivegagesbylimitingthelengthof "go"threadringgagestomaximumlengthsgivenincol.3 above .3) voidexcessivelycu mbe r somethreadpluggagesbylimitingmaximumlengthtotwodiameterswhereverposs ibk ' .4 )Takefulldvantageofmod ernquipmentorroducingndheck ingccurateleads,articularlywh ereongngagementsar envolved,husermittingtheus eof standardo rmoderatelengththreadplug,threadring,o rthreadsnapages.lternatively,fourse,nstrumentsightese dorcheck ingdiametersandnglesindependently.Shou ld "go"agehorterhanheengthfengagementehosen,independentmeansshouldese domeasureea deviationnroduct.Themaximummetalonditionmusteeducedossurereessemblyofroduct,fheea deviationnheengthfngagement,n,o determined,xceeds. 259O,heresheroductitchiameterallowance.heequiredmountfhang enitchiameter,f.',ftlieproduct(minuso nexternalthread,pluso ninternalthread)accordingly

Is:Ai'=3.80~(l- ')Jp,whe re/.,Is thelengthof thegageand/..is thelengthifengagement . Whennstrumentsar ese dorheck ingiametertsimplemattertomakehisallowance. Whenhreadlu gandinggages cused,theal lowanceissome t imesncreasedafixedamount,asoutlinedti h eabovetable. Thisarbitrarilyreducesthetoleranceondiameter.

1 7


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majoriameterfhenternalhreadithplustoleranceclassZ ,ootnoteftableXII.13 ) .Bothornerstheresthallehamferedequallytnnglef5,eaving idthfflatatrestf0.2Sp,0.00,0.02p.(b )Pitchd iame te r ,minordiameter ,andlength.Theitchiameter,minoriameter,ndengthofgagehallehesameshoseivenn(b),1 (c ) ,and(d )bove.3.NOTO"HREADLUGAGEO RITCHDIAMETERFLLNTERNALHREADS.(a)Majoriame te r .Theajoriameterfhe"noto"hreadlugagehallequalohemaximumbasic)majoriameterfhexternalthreadinus/4,ithheolerancetableXII.13,col .4 )ppliedminus.(b )itchiame te r .Theitchiameterhallbeheameshemaximumitchiameterfthenternalhread,ithheolerancetableXII.13,o l. nd)ppliedminus.(c )Minord iame te r .Theminordiameterhallclearadiameterlessby0 . 01n .thantheminimumminoriameterfhenternalhread.heclearanceutmayave.435pmaximumwidthbetweenintersections withtheflanksofthethread.{d)engthThelengthofthe"notgo"threadpluggageshouldpproximate3itchesseefoot-notetotableXII.14).henamultiplethreadis involved,the"notgo"threadpluggageshallb eofsuchlengthastoprovideatleast ullturnofthethread.4 .NOTGO"THREADLUGAOEORMAJORDIAMETERO FCENTRALIZINGINTERNALTHREAD.Themajordiametershallbeequalto the maximummajordiametero ftheinternalthread.hetoler-ancehallelass footnotefableXII.13),appliedminus.heincludedangleofhethreadshalle9 .heitchiameterhallehemaximumitchiameterofthelass4Central-izingxternalhreadforentralizingnternalthreads,lasses2C,3C,and4C)rthemaximumpitchdiameteroftheclass6Ccentralizingexternalthread(forcentralizinginternalthreads,classes5 C andC),ithminusolerancefwicehatgivennableII.13,olumn.herestcornershallehamfered5 quallyocaveaentralrestlatotorehan. 24 j /ide.TheapproximatedepthofcnamferisQ.07p.heminordiametershalllearadiameterlessby0 . 01 in.hanheminimumminoriameterfhen-ternalhread.heengthhouldpproximate3pseeootnoteoableII.14).henmultiplehreadsnvolved,henoto"ageshallb eofsuchlengthastoprovideatleast u ll turnofthread.5 .Go"LAINPLUGAGEFORMINORDIAM-ETERFNTERNALHREAD.Theiameterfthego"lainluggageshallbehesameasheminimumminoriameterfhenternalhread.Theageolerancehallelass footnoteftableXII.13),appliedplus.hegagelengthshallbenccordanceithheatestevisionfCommercialStandardCS8,GageBlanks.

6 .NOTGo"LAINLUGORMINORDIAM-ETERFNTERNALHREAD.Theiameterfthe"noto"plainluggageshallethesameastheaximuminoriameterfhenternalthread.heageolerancehallelass(footnotefableXII.13),ppliedminus.hegageengthhr.l leinccordancewithhelatestrevisionofCS8.(d)CONCENTRICITY

Methodsfecuringoncentricityetweenmajoranditchiametersofexternalrinternalthreadsmusteeterminedorachndividualapplication.SECTIONXIII.TUBACMEHREADS4

1.E N E R ALANDISTORICAL Whenormulatedrioro8 9 5 ,egularAcmethreadswerentendedoeplacequarehreadsand arietyfhreadsftherormssedchieflyorheurposefroducingraversingmotionsnachines,ools,tc.cmehreads

r.renowextensivelyusedforavarietyofpurposes.SectionII,.,rovidesnformationnddataertainingohesefheegulartand-ardAcmehreadorm.heStubAcmehreadcamentoeingarlynhe90 's .tssehasbeenenerallyconfinedohoseunusualpplica-tionswhereacoarse-pitchthreadofshallowdepthisequiredueoechanicalretallurgicalconsiderations.Whilethreadsforvalveoperationmaybemadetothisstandard,thisapplicationishighlyspecial-izedndheseatahouldotesedithoutconsultationwiththevalvemanufacturer.2.SPECIFICATIONSFO RTHESTUBA C M EF O R M O FTHREAD

1 .NGLEFTHREAD.Thenglebetweenheflanksfhehreadmeasurednnxiallaneshalle9.heineisectinghis9ngleshalleerpendicularohexisfhehread.2.ITCHFHREAD.Theitchf hreadisheistance,easuredarallelotsxis,betweenorrespondingointsondjacenthreadforms.3.EIGHTFHREAD.TheasiceightfStubcmehreadshallesollows:StandardStubAcme.3p,ModifiedForm StubAcme 0.375p,ModifiedForm2StubAcme 0.25p.4 .HICKNESSO FTHRE\D.Thebasicthicknesso fhehreadt iametermalleryheasicheight o fthread(forwhichseepreviousparagraph)thanhebasicmajordiameter,shalle0 .5/ ) .5 .LLOWANCEMINIMUMCLEARANCE)TMA-JORN DINORIAMETERS.inimumia-metricallearancesprovidedtheminordiam-eter o f all Stub Acme thread assemblies by

'TillssectionI sInsubstantialagreementwithAmericanStandardsAsso-ciationpublicationAS ABIS."StubAcmeScrewThreads,"whichispub-lishedyheSM F . . .t)thSt.,NewYork8 ,N.Y.helatestrevisionhouldbeconsultedwhenreferringothisASAdocument.1 8


26/74

establishingheaximuminoriameterfexternalhreads.020n.elowheasicminordiametern0pindoarser,nd.010n .belowheasicminoriameterorineritches.A minimumdiametricallearanceathemajordiameteris obtainedbyestablishingtheminimummajoriameterfhenternalhread.020n.aboveheasicmajoriameteror0pindcoarser,nd.010n .boveheasicajordiameterforfinerpitches.6 .ASICHREADORMIMENSIONS.ThebasicimensionsfhetandardtubcmethreadormorhemostenerallyseditchesaregivenintableXIII.1.hebasicthreadformissymmetricalandsllustratednigureXIII. 1 .TABLEIII.1.- -Standardtubcmehreadorm,asicdimensions

TotalIl.icht heightofThreads Pitch,p ofthread thread,perinch,n (basic), .=+0.3p ^ allow-ance

1 2 3 * in . in . in.160.06250 0.01875 0.023814.07143 .02143 .026412.08033 .02500 .030010.10000 .03000 .04008 .11111.12500

.1428.16667

.03333.03750

.04285.050(10

.0433.0475

.0529.ma m 87 6...5.20000 .06000 .0700 4 .25000 .07500 .08503W.28571 .08 571 .0057 3.33333 .10000 .11002\i.40000 .12000 .13002 .50000 .150110 .itaioIM.66667 .20(100 .2100m.75000 .22500 .23501.00000 .300(10 .311) I Widthofflat t: Threadthickness(basic),f-P/2in.0.03125.03571 .04167.05000 .05556.06250.07143.08333.Kim .1251.142X6.16687.20000.2501.33333.37.51 .MH> ("restofinternalthread(basic),0.4224p Hootofinternalthread,r".,-0.4224p-0.2.WXal-iowancein.0.IC64.0302.0352.0422.O40M.0528.0HI3.0704.0845.1056.1207 .1408.f lM I.2112.2 8 K ' ..3168.42241 0.0238.027. 0326. 0370. 0 4 1 7. 0 4 7 6.05S1.0652.07M3.1004.115.5.1356. 1 6 3 8. 2 0 6 0. 2 7 6 4. 3 1 1 6. 4 1 7 2

AllowancesshownnableXIII.3,col.3.

(a)pecialrequirement*..nation*fromnominaldiame te r .Applicationsequiringpecialmachin-ingrocessesesultingn asiciameteress thanheominalhownnableXI11.2,olumn1 ,hallhaveallowancesandolerancesinaccord-ancewithootnote,ableXIII.3;ableXI1I.4;andtabulatedtolerances,ableXI11.5.(b )pecialiameters .SpecialiametersotshownnableXI11.2ndo tivisibley/1 6 shallhowhectualasicajoriametern decimalsnrawings,pecifications,ndools.

3.TANDARDSTUBACMETHREADERIESTherehaseenelected eriesfiametersandssociateditchesftandardtubcm e

threadsistednableI11.2,hichsecom-

mendedsreferred.heseiametersndpitcheshaveeenarefullyelectedomeethepresenteedswithheewestumberftems,inrderoeduceo minimumhenventoryo fbothtoolsandgages.4 .LASSIFICATIONANDOLERANCES,TAND-ARDTUBACMEHREADS

Theresstablishedereinnlynelassfthreadorgeneralsage.hislassorrespondstoheclass2GGeneralPurpose)fsectionXII.If i tavingessacklashsequired,hetolerancesndllowancesoreneralurposethreadshownnablesII.3,II.4,II.5,Xli.ti,ndXII.8,p. o,mayesedodetermineheimitsfizeormatinghreads.1 .ASICIAMETERS.Theaximumajordiameterfhexternalhreadsheasic(nominal)majoriameter.heminimumitchdiameteroftheinternalthreadisbasicandequaltoheasicajoriameterinusheasicheightfhread.heasicminoriameterstheinimuminoriameterfhenternalthreadndsqualoheasicmajoriameterminustwicethebasicthreadheight.2.ENGTHFNGAGEMENT.Theolerancesspecif iedhereinareapplicabletolengthso fengage-mentotxceedingwiceheominalajordiameter.3 .OLERANCES.Theolerancespecifiedresuchasoassureinterchangeabilityandmaintainahighgradeofproduct.Thetolerancesondiametersofinternalthreadsshalleppliedlusromheminimumizesoabovetheminimumsizes.

Thetolerancesondiametersofexternalthreadsshalleppliedminusromhemaximumizestobelowtliemaximums izes .Theitch-diameterorhread-thickness)oler-ancesornxternalrnnternalhreadretheame.itchiameterolerancesrehesameasthosegivennableXII.6,p..Thepitch-diametero rhread-thickness)oler-ancesorheroductncludeeadndngledeviations.The tolerances onthemajorandminordiameterso fxternalndnternalhreadsorseithspecialhreadsareistednableXIII.3ndrebasedonhefollowingformulas:

Majordiame ITtolerance MinordiametertoleranceExtern!hread Internalhread Externalthrow! Internalthread

0.05p.Min-o/m". l.OXpttchdiametertolerance.''l.nxpitchdiametertolerance.1 *

n . 1 1 5p.(Min-0.005n.).

Toavoidacomplicatedormulaandstillprovideanadequatetolerance,thepitchactorisusedasabase,withheMinimumolerancevaluesetat0.l5In .* 'ForuseonlywherehemajordiameterofhenternalhreadandheminordiameterofheexternalhreadmustK-controlled,uchasonhin-waHedcomponents.itch-diametertolerancesorvariouspracticablecoin-IinationsofdiameterandpitcharegivenintableXII.6,p.7 .

19


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FIGUREXIII.1.StandardStubAcme formofthread.NOTATION 2a-29

p-pitchn=numberof threadsper InchN-numberof turnsper inchA =-0.3p basicheightof thread F..-0.4224p-baslcwidth,offlati> .crestof internalthreadF-0.4224p-baslcwidthofflatof crestof externalthreadFr.=0.4^4p=0.259X(majordiameterallowanceoninternalthread)F , .-0.4224p=0.259X(minordiameterallowanceon externalthread)

4 .LLOWANCESMINIMUMC L EA R A N C ES ) . A l -lowancesppliedoh eitchiameterfh e externalhreadarebasedo nh emajord iameterandaregivenintableXIII.4.W h e nh eproducth asalengtho fengagementgreaterhanh etandardengthfhreading{ jageass h o w nntableXII.14 ,col.3 ,p.7 ,n d ead deviationsnotexceedingvaluess howninth e footnotetothattable,andwhen" g o "threadringgages o ftheselengths areto b eused,th emaximum pitchiameterfh externalhreadhalledecreasedb yh eamountshownintableXII.14,col.5 .ftheleaddeviat ionsinh eproductaregreaterthanindicated,theallowancefo rth eringgagestatednol. shouldeincreasedropor-t ionately.owever ,fe t hodsfagingh e externalhreadreoesedhatil letect

angleeviat ionndumulat iveeadeviation,theitchiametero fh ehreadhal leelow th etabularmaximum pitch diameter byan amountsufficientocompensatefo rh emeasuredevia-t ions .A nncreasef0ercentnh el lowancesr ecommendedorac hnch ,rractionhereof ,thatheengthfngagementxceedsw o diameters .

5 .LIMITSO FSIZE,STANDARDSTUBA C M E THREADSLimi t sfiz eo rtu bcm ehreadsfh e

preferredserieso fdiametersan dpitchesaregiven mableI1I.5. Th eapplicationfhe sel imit s20


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isllustratednigureTII.2. Thealuesn tableXIII.5arebasedo nth efollowingformulas:ExternalThreads(Screws) (Basic) M axmajordiam=Nominalsizeo rdiameter ,D .M inmajoriam=Extm axmajordiamm i n usolerancero mable XIII.3,co l6 .M ax pitch diam=Int m in pitch

diam minusallowancefromable XIII.4,co l3.M in pitchiam=Ext m ax pitch diamm i n usolerancero mableXII.6,p.M axi no riam=Intininordiam m i n usallowancefromableXIII.3,co l4 .M inm in o riam=Extm axm i no rdiamminusolerancero mable XIII.3,co l7 .InternalThreads(Nuts ) M inmajoriam=Extm axm a jo rdiamlu sllowancero mableXIII.3,co l3.Maxmajoriam=Intinajordiamlu solerancero m tableXIII.3,co l7 .(Basic) M initchiam=Extaxajordiam m i n usbasiche igh tofthreadfrom tableXIII.2,co l8.

M axitchiam=Intinitchdiamlu solerancero mable XII.6,p.7 .(Basic)ininoriam=Extaxmajordiamm i n us2imesbasiceighto fthreadfrom tableXIII.2,co l8.M axinoriam=Intini no rdiamlu solerancero mableXIII.3,co l5.6 .HREADDESIGNATIONS

StandardStubAcmethreadsshal lbedesignated asshownbelowo ndrawingsandinspecifications, an dontoolsan dgages:Right-handthread:-20TUBCM E 'Righthand (sincedesig-nation LHisnotspecified)-Threadseries-Numberofthreadspe rinch 1Nominalsizeininches Left-handthread:-20TU BC M E L H

V r -

VT " C LefthandThreadseries Numberofthreadsperinch 1Nominalsizeininches TABLEXIII.2.StandardStubAcme threadseries,asic diametersandthreaddata

Threadsper inch,nBasicdiameters Threaddata

Nominalsites Majordi -ameter,D Piicndi-ameter,E-D-kMinordi -ameter,K=-D-2k Pitch,p

Threadthick-nessatpitchline,f-p/2Basicheight ofthread,=0.3p

Basicwidth of flat,F=0.4224p Leadangleatbasicpitchdiameter,X

1 2 3 4 5 6 7 8 9 10in .M 161 4 121210

8 665554444 13322222

in .0.2500 .3125.3790.4375.5000.629.'.7500. 8750l.OUOO

1.12901.25001.37501.50001.79002.00002 2500 2.90002.75003.00003.50004.00004.90009.0000

in .0.2312.2911. ***S .il29.4700.5879.7000.8290 .9400

1.06901.19001.30001.42901.67501.92502.15002.4000 2.65002.89003.3500 3.89004.39004.8900

0.2125.2606.3290.3879.4400.5500.6900.7750.8800

1.00501.13001.22901.39001.60001.89002.09002.30002.95002.70003.20003.70004.20004.7000

in.0.06250.07143.08333.08333.10000.12500.16667.16667.20000.20000.20000.25000.25000.29000.25000.33333.33333.33333.90000.90000.90000.90000.90000

in .0.03125.03572.04167 .04167 .05000.06250.08333.08333.10000.10000.10000.12900.12500.12900.12500.10667.16667.16667 .25000.25000.25000.25000.29000

in .0.01875.02143.02500.02500.03000.03750.05000.05000.06000.06000.06000.07500.07500.07500.07500.10000.10000.10000.19000.15000.19000.15000.15000

in .0.0264.0302.0352.0352 .0422.0528 .0704.0704.0845.0845 .0845.1056.1056.1056.1096.1408.1408.1408 .2112 .2112.2112.2112 .2112

( t e g m in 4 94M t 4 28 i"4 20 ft, 3 41H 3 92H3 52H 4 20u . : 3 41i 3 52m3 25 1M 3 4 m 3 301) 4 3 121H2 432 2 222M2H 2 50 2 32 2H 2 18 3 3 12t\i 2 434 2 22 4H2 66 1 53

21


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7 . ALTERNATIVE S TUB ACMETHREADSRecognizingheacthathetandardStubA c m ehreadormm ayo trovide enerallyacceptable threadsystem to m e e tth e requirementso fal lapplications,basicdatafo rtw oo ftheothercommon lysedormsreabulatednablesXIII.6ndXIII.7.he sethreadsareident i f iedas Modif iedForm StubA c m eThread( shownon fig.III.3)ndodif iedo rm Stubcm eThreadshownnig .III.4).herever

practicable,owever,hetandardtubcm eThreadform shouldbeused.Inapplying theforegoingdatatospecialdesigns,th e allowances andtolerances canbetakendirectly fromtablesXIII.3,XIII.4,n dXII.6,. o rstandardtubcm ehreads.hereforehemajoriameterndasichreadh icknesstpitchin eo rbo thxternalndnternalhreadswillbeth esameas fo rthestandardform as s h o w nTABLEXIII.3.Tolerances nd l lowancesfo rmajor nd minordiameters,StubAcmethreads*

Threadsperinch,n

Allowancesfrombasicmajorandminordiameters Toleranceonminordiameter,allinternalthreads,plus0.05p

Toleranceonmajordiameter,allexternalthreads,minus0.05p

Toleranceon* majordi-ameter,lusonallInternalthreads;alsotoleranceonminordiame-ter,minusonall externalthreads,-1.QXP.D.tol.

Size Majordiam,allin-ternalthreadsplus

MinorJdiam,allex-ternalthreadsminus1 2 3 4 6 6 7

in.MHhiHH.-u116 14 1212 10 8 6655 5 444433322222

in.0.010.010.010.010.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020

in.0.010.010.010.010.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020.020.02 0 .020.020

in.0.0050.0050.0050.0050.0050.0062.0083.11083.OHM .0100.0100.0125.11125.0125.0125.0167.0167 .0167.0250.02.50 .0250.0250.0250

in.0.0050.0050.0050.00.50 .0050 .0062.0083.0083.0100 .0100.0100.0125.0125.0125.0125.0167 .0167 .0167 .0250.0250.11250.0250.0250

in.0.0105.0114.0123.0126.0137.0154.0174.017.01041)4

1MHi1)4IM 2.01!.0201.0220.0223.022.02352M2H33H44)5 .0263.0268.0273 .031.0324.0332.033.0346 Pitch-diametertolerances fo rvariouspracticablecombinationsofdiameterandpitchareRivenIntableXII.6,p.7.Ior anintermediate size,thetolerancesanddeviationsfor thenextlarpersizegiveninthistableshallapply.Theminimumclearanceatthemajordiameterbetweentheinternalandexternalthreadsisequaltocolumn3.JTheminimumclearanceattheminordiameterbetweentheInternalandexternalthreadsisequaltocolumn .Toavoidacomplicatedformulaanilstillprovideanadequatetolerance,thepitchfactorsusedasabase,withheminimumolerancevaluesetat0.005in.'Foruseonly where the majordiameteroftheinternalthreadandthe minordiameteroftheexternalhreadmustbecontrolled,suchasonhin-walledcomponents.

intablesXIII.2andXIII.5.hepitchdiameteran dm i n o rdiameterwillvaryfromthedata s hown intablesXIII.2andXIII.5;fo rmodif iedform,theitchn di no riametersil lemallerthans imilarvaluesfo rthestandardform,an dfo rmodif iedform 2thepitchan dm i n o rdiameters willb elargerhanthosedimens ionsfo rth estandardforms.Thesehreadshal leesignatedsh o w n belowonrawingsndnpecifications,n dn toolsan dgages:Right-handthread: -Modif iedForm

)420STUBA C M EMlH20STUBA C M EM 2 odif iedForm 2

Left-handthread:Yr-20STUBA C M EMl-LHM-20STUBA C M EM 2 L H

TABLEXIII.4.Plt~hiameterallowancesforStubcmethreadsNominalsizerange Fitchiameter1'allowancesonx-

ternalthreads,0.008-/D

Tlie valuesincolumn3 aretobeusedfo ranynominal size withintherangeshownncols nd .hesevaluesarecalculatedromhemeanofherange.ItsrecommendedhathenominalizesgivennableXIII.2beusedwheneverpossible.bAnncreaseof10percentintheallowanceisrecommendedfo reachInch,orractionhereof,hatheengthfengagementexceedswoiameters.

22


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to 8 |S s 3.8 * r t& 3 a

sss =sss4ii.885?

HlSS 1 1 1 4SI I'M 1 1 1

383 S33Pt-i-c5 1 2 car? illo i f f i as* gjejIII-3te2-SSo fe i fsi II

2Rf3 = oeaclit 8RS |S3IKS 3 ? S S I ? S 3 ? 13 3 .saaIIIiii1 1 ?3S 80S 888

JS| 2$ag sss III 1 000.888 883 IP.85si h>9r- sgg o o S e c o c nof cSS

?$3 gI2 no -* c*c1 * S0 5; SSo Wm38S-TO in iss*SS

to-rite5^S 8ss rtS= B B S X riO W |fSS3 888.ass 1 1 = IIISSSegsssssrs s Iii 2tssS3c5S N8S5

E 5

s

= re55s-

e a u25

5H s5o s5a . . - ".5f- ZSf-

E 5a

1 a

2 3


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INTERNAL THREAD (NUT)

EXTERNAL THREAD ( SCREW )

FIGUREXIII.2.Illustration fallotvances,olerances, ndcrest learancesforStubAcmethreads.NOTATION

p-pitch-basic threadheight

24


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TABLEXIII.6.ModifiedForm tubAcmehreadform,basicdimensionsThreadsperInch,

n

Pitch,

P

Heightofthread(basic),-0.375p

Totalheightofthread,ft.-+ttallowance*

Threadthickness(basic),f-p/2

WidthfflattcrestofInternalthread(basic),F-0.4030p

1 2 3 4 5 616in.0.06250.07143.08333.10000.11111.12500

.14286.16667.20000.25000.28571 .33333

.401100.50000.66667.750001.00000

in.0.02344.0267J.03125.03750.04167.04688.05357.06250.07500.09375.10714.12500.15000.18750.25000.28125.37500

in.0.0284.0318 .0363.0475.0517.0569.0636.0725 .0850.1038.1171.1350 .1600.1975.2600.2913.3850

in.0.03125.03572.04167.05000.05556.06250.07143.08333.10000.12500.14286.16667 .20600.25000.33333.37500.50000

in.0.025214.028812.033610.040398.0448.05047.05766.06725.08064.10118 8H.11513.13432H2Hi.1612.2015.2687mi.3023.4030

AllowanceIsshownIntableXIII.3,column 4 .

TABLEXIII.7.ModifiedFormSStubAcmehreadform,basicdimensionsThreadsperInch,

n Pitch,

P

Heightofthread(basic),ft -0.250p

Totalheightofthread,ft.-ft+Hallowance"

Threadthickness(basic),f-p/2

WidthfflattcrestfInternalthread(basic),F..-0.4353p

l 2 3 4 5 616in.0.06250.07143.08333.10000.11111.12500

.14286.16867.20000.25000.28571 .33333

.40000.50000.66667.750001.60000

in,0.01563.01786.02083.02500.02778.03125.03571.04167.05000.0625007143.08333.10000.12500.16667.18750.25000

in.0.0206.0229.0258.0350.0378.0413.0457.0517.0600.0725.0814.0933.1100.1350.1767.1975.2600

in.0.03125.03571.04167.05000.05556.06250.07 14308333.10000.12500.14286.16667.20000.25000.33333.37500.50000

in.0.027214.031112.036310.04359.048487.0544.06226.07288.08714m3.1088.1244.14512 M2.1741.2177mmi.2902.3265.4353* AllowanceI s shownin tableXIII.3,column4 .

8 . GAGES FOR STUB ACME THREADSGagesrepresentingbothproductlimits,orade-quategaginginstrumentsforthreadelements,renecessaryfortheproperinspectionofStubAcmethreads.heimensionsfgo"ndnoto"

gagesshouldbeinaccordancewiththeprinciples:

(a)hathemaximum-metallimit,r"go,"gageshouldchecksimultaneouslyasmanyelementsaspossible,andthataminimum-metallimitor"notgo"hreadgagecaneffectivelycheckbuto n eele-ment;nd6 )hatermissibleariationsnhegagesekeptwithinhextremeroductlimits.(a)GA GEOLERANCES

Tolerancesforthethreadelementsof"go"and"notgo"hreadgagesforStubAcmethreadsareasspecifiedbelow.1 .OLERANCESNITCHIAMETER.ThepitchiameterolerancesoragesorxternalandnternalhreadsreivennableXIII.8,col.2 .2.OLERANCESNAJORN DINORI-AMETERS.Themajorndminoriameteroler-ancesortubcmehreadagesreivenn tableXIII.8,col .3 .3 .OLERANCESNEAO.-TIICariationnleadofallStubAcmethreadgages shallnotexceed0 . 0 0 0 3in .betweenany2threadsnotfartherapartthan n .owever,thecumulativedeviationinleatlhallotxceed. 0 0 0 4n.orgageswithlengthover o3n.,inclusive;or0.0005in.,orgageswith engthver o n.,nclusive;r0 . 0 0 0 7in.,forgageswithalengthover5to0in.,inclusive.ormultiplehreadsheumulativetoleranceforanylengthofgageshallbeobtainedbymultiplyingy.5heboveoleranceppli-cabletothatlength.

INTERNALTHREAD(NUT)

h-0.}T5p---

EXTERNALTHREAD(SCREW)

FIGCREXIII.3.ModifiedFarm tubAcmehreadwithbasicheightof0.375pitch.///.//' '.' :: ''. ; INTERNALTHREAD(NUT)

FIGUREXIII.4.ModifiedForm2StubAcmehreadwithbasicheightof0.25pitch.

25


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TABLEIII.8.Tolerancesforg o"nd"noto"hreadgage s ,StubAcmethreadsThreadsper inch Tolerancesnpitchdiameter b Toleranceon majoran dminordiameters

Toleranceon half angleof thread1 2 3 4

16 in .0.0006 .0006.0006.0007 .0008.0008 .0009.0009.0010.0011.0013.0013.0014.0015.0018 .0018 .0021

in . 0.001.001.001.002.002.002.002.002.002.002.002.002.002.002.002.002.002

minute 1 0 141 0 121 0 101 0 9.1 0 8 878 68548 83'A32H2M8 06f i 55 5 Intermediatepitchestakethetolerancesofthenextcoarserpitchisted inthistable.bThesepitchdiametertolerancesforthreadgagesare no tcumulative,thatIs,theydo no tincludetolerancesonleadandonhalfangle.

4 .OLERANCESNNGLEFHREADS.Thetolerancesonangleofthread,asspecifiedintableXIII.8,o l. orheariousitches,reoler-ancesnne-halfhencludedngle.hisn-sureshatheisectorfhencludednglewillbeperpendicularohexisofthehreadwithinproperlimits.heequivalentdeviationfromthetruehreadormausedysuchrregularitiessconvexroncaveidesfhehread,rlightprojectionsonthethreadform,shouldnotexceedthetolerancespermittedonangleofthread.(b)OAQESFO REXTERNALTHREADS

1 .GO"HREADINGRHREADNAPGAGE.(a)Majoriame te r .Theajoriam-eterfhego"hreadingrnapagehallclear iameterreatery.0 1n.hanhemaximummajordiametero fthexternalhread.(6 )itchiame te r .Theitchiameterhallfit.hemaximum-metalimithreadettingluggage.(c )Minordiame te r .Theminordiametershallbeheameshemaximumminoriameterftheexternalthreadplus0 . 0 0 5 in.orpitchesfinerthan0pindlus. 0 10n.or0pindcoarser. Thetoleranceshallb eppliedminus.(d)ength.ThtengthhallpproximatehelengthfngagementuthallotxceedhelengthspecifiednableXII.14 ,o l.3 ,.7 .2.MAXIMUM-METALIMITHREADETTINGPLUGFOR"GO"THREADRINGO RSNAPGAGES.(a)Major iame te r .Themajoriameterfhemaximum-metallimitthreadsettingplugshallhethesameshemaximummajordiameteroftheexternalhread.heageolerancehalle appliedplus.(b )itchiame te r .Theitchiameterhallbethesameasthemaximumpitchdiameteroftheexternalhread,xceptwhenmodifiednccord-

ancewithableXII.14,.7 .(c)Minordiameter.Theminordiametershallbeclearedelowtheminimumminordiameterofthego"threadringorsnapgage.(d)ength.Thelengthhallpproximatehelengthofthe"go"threadringorsnapgage.3 .GO"LAININGRNAPAGEORMAJORIAMETER.Theiameterfhego"plainingage,rheagingimensionfhe"go"lainnapage,halleheameshemaximummajordiameterofhexternalthread.TolerancesareshownnableXIII.9,o l.,ndshallbeappliedminus.4 .NOTGO"THREADRINGORTHREADSNAPGAGE.(a)Majordiameter.Themajordiameterofhenoto"hreadingrhreadnapageshallclearadiametergreaterby0 . 0 1 0in.thanthemaximummajordiameterofheexternalhread.(6 )itchiameter.Theitchiameterhallfitheminimum-metalimithreadettingluggage.(c )Minordiame te r .Theminordiametershallbethebasicminordiameteroftheinternalthreadplus0 .15p,withthetoleranceappliedplus.TABLEXIII.9.Tolerancesorlainages ,Stub Acmethreads

Siterange Tolerancesfor plainpluggagesTolerancesforplainringan d

Above To an d Including snapgages1 2 3 4

1 * .o.too.8251.5102.5104.510

in. 0.825 1.5102.5104.5105.000

in. 0.00010.00012.00016.00020.00025

in .0.00020.00024.00032.00040.00050

(d)ength.Thelengthshallapproximatethreefetchesxcept that, forultiple threads, theengthshallprovideatleastonefullturn ofthread.5 .MINIMUM-METALHREADETTINGLUGFORNOTGO"THREADRINGORSNAPGAGE.(a)Major iame te r .Themajoriameterfheminimum-metallimithreadsettingplugshallethesameshemaximummajordiameterofheexternalhread.heageolerancehalleappliedplus.(6 )itchiame te r .Theitchiameterhallbethesameastheminimumpitchdiameteroftheexternalhread,withheoleranceppliedlus.(c )Minordiame te r .Theminordiametershallb elearedelowtheminimumminordiameterofthenotgo"hreadage.(d)ength.Thelengthshalletleastqualtohelengthofthenotgo"hreadringorsnapgage.6 .NOTGO"LAINNAPAGEORMAJORDIAMETER.Theagingimensionfhenotgo"plainsnapgageshallbethesameasthemini-mumajoriameterfhexternalhread.

TolerancesarehownnableXIII.9,o l.,ndshallbeappliedplus.26


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(c)Q A G E SFORNTERNALTHREADS1 .GO "H R E A DLU GA G E .-a)ajor diameter.-Themajordiameterofthe" g o "threadplugagehallbequalohemin imummajordiameterofh enternalhreadminus. 005n.fo rpitchesf inerthan10pi ,ndm i n us0 .010in .fo r0pindoarser.h eolerancetableXIII.8,col.3)shal lbeappliedplus.(6 ) i tchiameter.Theitchiameterhal lbeequaltothem i n i m u m(basic)pitch diameterofth enternalhread,ithh eolerancetableXIII.8,col.2)appliedplus.(c )Minordiameter. T h em i n o rdiametershallclear iametermallery. 010n .hanh e min imumm i n o rdiametero fth enternalhread.(d) ength. Th elength shal lpproximateh e length ofengagement(see footnoteto tableXII.14,p.7 )uthal lotxceedwiceh eomina lmajordiameter,unlessotherwisespecified.2.N O TGO "THREADPLUGG A G EORPITCHDIA M ET ERFN T E R N A LHREAD.(O)ajor diameter.Themajoriameterfh enoto " threadpluggageshal lbeequaltoh emaximum (basic)ajoriameterfh externalhreadm i nu s.l5pi thh eolerancetableXIII.8,col.3 )appliedminus .(6 ) i tch iameter.Theitchiameterhal lbehesameshemaximumitchiameterfth enternalhread,i thh eolerancetableXIII.8,col.2)applied minus . (c )Minordiameter.Them i n o rdiametershal lclearadiameter lessb y0.01in .thanthem i n i m u m m i n o rdiameterofth einternalthread.(d)ength. T h e length shallapproximatethreepitches,exceptthatfo rmultiplethreadsth e length shallprovideatleastonefullturnofthread.3.GO "PLAINPLUGG A G EFORMINORDIAME-TE ROFINT ER NA LTHREAD.Thediameterofth e " g o "lainlu gag ehal leheam esh e min imumm i n o rdiameterofh enternalhread.Th e gage tolerance shal l b e applied plus.Se e table XIII.9,o l..)h eag eengthhallenaccordancewiththelatestrevision ofCommerc ia lStandardCS8,GageBlanks.4 .N O TGO "LAINLUGG A G EORMINORDIA M ET ERO FN T E RN ALTHREAD.Thediameterofthe" n o tgo "plainpluggageshal lb ethesame ashemaximumm i n o riameterfh enternalthread.hegagetoleranceshall b eapplied minus .(SeetableXIII.9,ol.3 .)h egagelengthshal lbeinccordancewithth elatestrevisiono fCS8,GageBlanks. ( d )CONCENTRICITYW h e n pecialheckfh eoncentricitye-tweenh emajor ,i tch,ndm i no riametersfanxternalrnternalhreadsequired,h e m e t h o dfheckingh isoncentricitymustedevisedfo reach ind iv idua lapplication.

(e)G A G EDIMENSIONSItsrecommendedhatwhereveross ibleh e generaldimensionsofth eagesenaccordance withth elatestrevisionofCS8,GageBlanks.

SECTIONX I V .N A T I O N A LBUTTRESSTHREADS61.ISTORICAL

Al thoughtheButtressthreadwasdescribedas earlyas March,1888intheJournalo fTheFrank-li nnsti tute,itwassolittleusedthatitsnationalstandardizationasotndertakenntilftertheCombinedConservationCommit teenarly1942reviewedthestandardizationstatusofi tems neededinthew areffort.ormerlyeachapplica-tiono ftheButtressthreadwastreatedndividu-allyan dtheformittookdependedontheexperi-encefhees ignerndheanufacturingequ ipmen tavailable.A th emerican-Brit ish-Canadianonferencein NewYork,calledbyth eCombinedConserva-tionommi t t e enovember ,943 ,uttressthreadswereiscussedndtwasgreedhatbasicprofileshou ldb eestabl ishedfo rthisthread,thathenterdepartmentalcrewThreadCom-mitteeISTC)ftheWar,Navy,andCommerce Departmentsshouldcollectdatao ncurrentprac-ticeof American producers ,an dthattheAmericanStandardsAssociat ionshouldistributehedatafo ro m m e n tro mndustr iess inguttressthreads.sheMilitaryDepartmentseededButtressndtherpecialypesfhreads,heWarroductionoardnebruary,9 44 ,r-rangedwiththeA SA to establ ishaGeneralWarCommi t t e eo nScrewThreads .InApril944 ,F.E.Richardson,henwiththeAeronautical oardnd m e m b e rfh e SA Warommi t t e encrewhreads ,ollectedin format iono nButtressthreadsandpresenteditatajointmeet ingo fth eBlSectionalCommi t t e eonh eStandardizationndUnificat ionfScrew Threads ,henterdepartmentalcrewhreadCommit tee ,an dth eGeneralA SA WarCommi t t e eoncrewhreads .h eatadisclosedhatthepressureflankangle,measuredin anxialplane,ranged from 0to morethan15 from th enormalto th exis,ndh elearancelankngleanged from 30to5 5 . TheISTCdecidedtodevelopaSroposedButtressthreado rm havingapressure anknglef ,whichloselypproachesh e staticnglefrictiono rell-lubricatedteelsurfacesincontact,an daclearanceflankangleo f4 5 .

Ath emerican-Brit ish-CanadianonferenceinLondon ,Augus tan d September,1944 ,sponsored byth e Combined Product ionan d Resources Board,th eritishroposed uttresshreadf.5 pressurelanknglen d 5 learancelankangle.h enitedtates'roposalasheISTC'secommendat ionf y5 hread[>rofile. Th eBrit ishagreedto preparean dcircu-ate raftpecificationo r Buttresshreadhavinga7 pressureflankangle,a4 5 clearanceThissectionisinsubstantialagreementwithAmericanStandardsAsso-ciationpublication SA1 .9 ,ButtressScrewThreads,whichispublishedbytheASME.2W .3W hStreet,N ew York8 ,N.Y.helatestrevision

shouldb econsultedw h e nreferringtothisA SA document.550170*60 27


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flankngle,nd asicepthfhreadngage-mentcfOAp.twasalsoagreedthatthespecifica-tionhouldncludeecommendedelationshipf'pitchodiameterandappropriateableso fclear-ancesandtolerancesforsuchrelationships.The9 4 4ditionfHandbookH28ublishedtheSTC'secommendationf asicButtressthreadformwhichhadacrestflatinheinternalthreadnut)wicehatfhexternalhread(screw),andathreadengagementdepthofapprox-imately0.56p.nNovember,1 9 4 4 ,theA SA WarSubcommitteenuttresshreadsasstab-lishedndftereviewingheritishraftfApril,9 4 5 ,hisommitteeelthatecauseofheistortionendencyfhinwallubing,greaterasicepthfhreadngagementhanOApwasesirable,speciallysinceheminimumdeptho fthreadengagementisnecessarilylessthanOApbyone-halfthesumoftheallowanceandthetolerancesnminoriameterfnternalhreadandmajoriameterfxternalhread.here-fore,heuly,9 4 5raftfheWarStandardwasbasedonabasicdepthofthreadengagementof0.5p.

AnotherAmerican-British-CanadianonferencesponsoredyheCombinedProductionndRe-sourcesBoardwasheldnOttawa,Canada,Sep-temberndctober,9 4 5 .ereheritishproposalfApril,9 4 5 ,withnlternateesignofressurelanknglend learancelankangleo f5 2 ,wasreviewedandomparedwiththeAmericanroposalfJuly,9 4 5 .earninghattheBritishhadhadonsiderableavorablexpe-riencenhinwallubingwithButtresshreadshavingOApbasicepthfhreadngagement,itwasecidedhathemericantandardmightadopthisasis.ccordaslsoeached. - < preferreddiametersandpitches,hreaddimensiontolerancesndllowances,ndnavingachstandardncludentsppendixnlternatethreadofressurelankngle.urther,achcountryagreedto publishthestandardin conform-ancewithheirrespectiveformats.InApril,9 4 6 ,buttressthreadswereassignedtoSubcommitteeNo. fheSectionalCommitteeonheStandardizationndUnificationfScrewThreads,Bl,ndhecommitteemembershipwasenlarged.hisommitteereparedndircu-latedn9 4 8omembersfhe lommittee,drafto faproposedstandardbasedontheBritishproposalwithabasichreadepthfOAp.hecommentsncludedoanybjectionsoheshallow depthofthreadthatin1 9 4 9 thecommitteedecidedtobasethenextdraftonathreadhaving0.6pngagementepth.heommitteelsovotednottoincludeintheappendixoftheAmeri-cantandard,ataor uttresshreadaving0pressureflankangleasitwasevidenthatthiswasnlynefseveralmodificationshatmightbeneededforspecialapplications.ThenextAmerican-British-Canadianconferencewascalledattherequesto ftheDirectorofDefenseMobilizationandheldinNewYorkinJune,9 5 2 .Theritishtandard 1 6 5 7 ; 1 9 5 0oruttress

Threadswhichsasedn hreadngagementdepthofOApandheAmericandraftof Septem-ber,9 5 1 ,asednhreadngagementepthf0.6pwereeviewed.twasoncludedhatheapplicationsforbuttressthreadsaresovariedthatthreadsithitherngagementepthOApr0.0p)mightereferredorparticulardesigne-quirements.twasecommendedhatheextprintingfheritishtandardndheorth-comingmericantandardncludehessentialdetailsoftheothercountry'sstandardsinppen-dixes.SABl.9-1953,uttressScrewThreads,wasissuednonformancewithhisrecommenda-tion.

2.GENERALTheuttressormfhreadasertaind-vantagesnpplicationsnvolvingxceptionallyhightressesnneirectionnly,longhethreadxis.shehrustidefhehreadsmadeeryearlyerpendicularohehreadaxis,theradialcomponentofthethrustisreducedto minimum.nccountfhemalladialthrust,hisormfhreadsarticularlypplic-

ablewheretubularmembersarescrewedtogether.Examplesfctualpplicationsrehereechmechanismsfargeunsndirplaneropellerhubs.A shesefuttresshreadsppliesmainlytopeciallyesignedomponents,taseenconsideredthatnousefulpurposewouldbeservedbyntroducingecommendediameter-pitchseries.Inelectingheormfhreadecommendedastandard,manufactureyhehreadmillingorgrindingprocesseshasbeentakenintoconsider-ation.hereverossibletsecommendedthatheormfhreadndolerancesontainedinhissectioneused.

3.PECIFICATIONS1 .COPE.Thisectionelatesohreadsfbuttressormndrovides:(a)standardormofthread,(6 ) tablesofpreferrediametersndreferredpitches,(c) ormulaoralculatingitchiametertolerances,(d)olerancesormajorndminoriameters,(e )ystemfllowancesetweenatingparts,and(/)ecommendedmethodso fgaging.2 .EFINITIONS.Theressurelankshatwhichakeshehrustroadnnssembly.Thelearancelankshathichoesotakethehrustroadnnssembly.3 .ASICORMFHKEAD.Theasicormo fheuttresshreadshownnigureXIV.l,andasheollowingharacteristics:(a) ressurelankngle,easuredn