AMERICANSTANDARDMicroscopeObjecti.veThre-ad..ASAB1.11-1958UDC621.882.082:535.822:681.42-~-~.~~-...REAFFIRMED1994FORCURRENTCOMMllTEEPERSONNELPLEASESEEASMEMANUALAS-11REAFF:IRMED1989FORCURRENTCOMMllTEEPERSONNELPLEASESEEASMEMANUALAS-fl-.,.......SocietyofAutomotiveEngineersTheAmericanSocietyofMechanicalEngineersTHEAMERICANSOCIETYOFMECHANICALENGINEERS29West39thStreet,NewYork18,N.Y.REAFFIRMED2016IntentionallyleftblankERRATAANSIB1.ll-1958(R1972)MICROSCOPEOBJECTIVETHREAD(JULY1972)Page5,Section7shouldread,AmericanNationalStandardANSIB1.7-1965(R1972)Page6,Section14shouldread,AngleDeviation.ForewordThestandardizationofthemicroscopeobjectivethreadisoneoftheprojectstowardunificationofscrewthreadstandardsamonginch-usingcountries.InGreatBritain,theRoyalMicroscopicalSocietyhadestablishedstandardsformicroscopeobjectivesin1858,basedontheWhitworthscrewthreadsystem,whichweresubsequentlyusedthroughouttheworld.ThehistoryofthisstandardisintheTransactionsoftheSociety:1858,p.39;1859,p.92;1896,pp.389,487;1911,p.175;1915,p.230;1924,p.266;and1936,p.377.Inpractice,AmericanmanufacturersofthisthreadhavealwaysemployedmodificationsoftheWhitworthformbecauseoftheirpreferenceforflatcrests,suchmodifiedthreadsbeingcompletelyinterchangeablewiththeRMSthreads.AttheConferenceonUnificationofEngineeringStand-ardsheldinOttawa,1945,theAmericanDelegationpresentedASAPaperB1/57andA.O.DrawingED-95givinglimitsofsizeforatruncatedWhitworththread.SinceathreadformwithroundedcrestispreferredinGreatBritainforopticalinstruments,itwasrecommendedthatthetitleofthisdocumentbeamendedtoread,“ProposedPermittedTruncationandTolerancesforRMSThread.”OnthebasisofthisproposaladraftofaproposedAmericanStandard,datedApril,1948,wascir-culatedtotheB1SectionalCommitteemembershipforcomment.Inconformitywithcommentsreceived,areviseddraft,datedOctober,1954,wasapprovedbySubcommitteeNo.4onInstrumentScrewThreadsandsubsequentlysubmittedtotheSectionalCommltteeforapproval.FinalapprovalasanAmericanStandardwasgivenonJanuary7,1958,byASA...Anypartofth...
