>> P.551
HeightGagesTakingReadingsVernierHeightGage(2)6543210111097(1)76543210111097(1)VernierscaleMainscaleMinimumreading:0.02mm(1)Mainscalereading:(2)Vernierscalereading:790.36mmmmVernierheightgagereading:79.36mmMechanicalDigitHeightGageMeasuringupwardsfromareferencesurfaceScribingstylus122.11ReferencesurfaceA00901010900.1mm8020307020807030122mm406060405050878mm(1)Counterreading:(2)Graduationsreading:122mm0.11mmMechanicaldigitheightgagereading:122.11mmMeasuringdownwardsfromareferencesurfaceReferencesurfaceB90100010900.01mm2080703080203070875mm406050506040125mm(1)Counterreading:(2)Graduationsreading:125mm0.11mmMechanicaldigitheightgagereading:125.11mm125.11ScribingstylusGeneralNotesonUseofHeightGages1.PotentialcausesoferrorGiventhatthisheightgageisameasuringinstrumentthatdoesnotconformtoAbbe'sprinciple,thefollowingerrorfactorsarepossible.•Parallaxerror•Excessivemeasuringforce•Differentialthermalexpansionduetoatemperaturedifferencewiththeworkpiece•Structureoftheheightgage.Inparticular,structureanderrorfactorsrelatedtoa“referenceedgewarping”and“scriberinstallation”describedbelowshouldbefullyunderstoodbeforeuse.2.Referenceedge(column)warpingandscriberinstallationAsshowninthefollowinggure,measurementerrorsresultwhenusingtheheightgageifthereferencecolumn,whichguidestheslider,becomeswarped.ThiserrorcanberepresentedbythesamecalculationformulaforerrorscausedbynonconformancetoAbbe'sPrinciple.Here,installingthescriber(oralever-typedialindicator)requirescarefulconsiderationbecauseitaffectsthesizeofanyerrorduetoawarpedreferencecolumnbyincreasingdimensionhintheaboveformula.Specically,payattentiontothefollowingwheninstallingthescriber.•Makesurethatthedimensionhinthefollowingformulaisnottoolarge.•Installthescriber,etc.,sothatitdoesnotprotrudetoofarforwardfromthemainbody.Becarefulwhenusinganoptionallongscriberorlever-typedialindicator,astheerrorfactorwillgrowlarger.13-24HeightGagesℓℓhℓExample:EffectofmeasuringpointpositionWhenhis150mm,theerroris1.5timeslargerthanwhenhis100mm.hhfla
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