>> P.279
HowtoreadVernierHeightgage76543210111097(1)(2)6543210111097(1)VernierscaleMainscaleGraduation0.02mm(1)Mainscale(2)VernierReading79mm0.36mm79.36mmGeneralnotesonuseofHeightGages1.PotentialcausesoferrorLikethecaliper,theerrorfactorsinvolvedincludeparallaxeffects,errorcausedbyexcessivemeasuringforceduetothefactthataheightgagedoesnotconformtoAbbe'sPrinciple,anddifferentialthermalexpansionduetoatemperaturedifferencebetweentheheightgageandworkpiece.Therearealsoothererrorfactorscausedbythestructureoftheheightgage.Inparticular,theerrorfactorsrelatedtoawarpedreferenceedgeandscriberinstallationdescribedbelowshouldbestudiedbeforeuse.2.Referenceedge(column)warpingandscriberinstallationLikethecaliper,andasshowninthefollowinggure,measurementerrorsresultwhenusingtheheightgageifthereferencecolumn,whichguidestheslider,becomeswarped.ThiserrorcanberepresentedbythesamecalculationformulaforerrorscausedbynonconformancetoAbbe'sPrinciple.f=h=haℓhflℓθhfalhInstallingthescriber(oralever-typedialindicator)requirescarefulconsiderationbecauseitaffectsthesizeofanyerrorduetoawarpedreferencecolumnbyincreasingdimensionhintheaboveformula.Inotherwords,ifanoptionallongscriberorlever-typedialindicatorisused,themeasurementerrorbecomeslarger.hθaℓExample:EffectofmeasuringpointpositionWhenhis150mm,theerroris1.5timeslargerthanwhenhis100mm.hℓh3.LiftingofthebasefromthereferencesurfaceWhensettingthescriberheightfromagaugeblockstack,orfromaworkpiecefeature,thebasemayliftfromthesurfaceplateifexcessivedownwardsforceisusedontheslider,andthisresultsinmeasurementerror.Foraccuratesetting,movethesliderslowlydownwardswhilemovingthescribertiptoandfrooverthegaugeblocksurface(orfeature).Thecorrectsettingiswhenthescriberisjustfelttolightlytouchasitmovesovertheedgeofthesurface.Itisalsonecessarytomakesurethatthesurfaceplateandheightgagebasereferencesurfacearefreeofdustorburrsbeforeuse.MechanicalDigitHeightgageMeasuringupwardsfromareferencesurfaceScribingstylus122.1Referencesurface90100010900.1mm2080703080203070122mm406060405050878mmCounter122mmDial0.11mmReading122.11mmMeasuringdownwardsfromareferencesurfaceReferencesurface90100010900.1mm2080703080203070875mm406060405050125mmCounter125mmDial0.11mmReading125.11mm125.11Scribingstylus4.Errorduetoinclinationofthemainscale(column)AccordingtoJISstandards,theperpendicularityofthecolumnreferenceedgetothebasereferencesurfaceshouldbebetterthan:()mmLindicatesthemeasuringlength(unit:mm)0.01+1000LThisisnotaveryonerousspecication.Forexample,theperpendicularitylimitallowableis0.61mmwhenLis600mm.Thisisbecausethiserrorfactorhasasmallinuenceanddoesnotchangetheinclinationoftheslider,unlikeawarpedcolumn.5.RelationshipbetweenaccuracyandtemperatureHeightgagesaremadeofseveralmaterials.Notethatsomecombinationsofworkpiecematerial,roomtemperature,andworkpiecetemperaturemayaffectmeasuringaccuracyifthiseffectisnotallowedforbyperformingacorrectioncalculation.6.Thetipofaheightgagescriberisverysharpandmustbehandledcarefullyifpersonalinjuryistobeavoided.7.Donotdamageadigitalheightgagescalebyengravinganidenticationnumberorotherinformationonitwithanelectricmarkerpen.8.Carefullyhandleaheightgagesoasnottodropitorbumpitagainstanything.Notesonusingtheheightgage1.Keepthecolumn,whichguidestheslider,clean.Ifdustordirtaccumulatesonit,slidingbecomesdifcult,leadingtoerrorsinsettingandmeasuring.2.Whenscribing,securelylockthesliderinpositionusingtheclampingarrangementsprovided.Itisadvisabletoconrmthesettingafterclampingbecausetheactofclampingonsomeheightgagescanalterthesettingslightly.Ifthisisso,allowancemustbemadewhensettingtoallowforthiseffect.3.Parallelismbetweenthescribermeasuringfaceandthebasereferencesurfaceshouldbe0.01mmorbetter.Removeanydustorburrsonthemountingsurfacewheninstallingthescriberorlever-typedialindicatorbeforemeasurement.Keepthescriberandotherpartssecurelyxedinplaceduringmeasurement.4.Ifthemainscaleoftheheightgagecanbemoved,moveitasrequiredtosetthezeropoint,andsecurelytightenthexingnuts.5.Errorsduetoparallaxerrorarenotnegligible.Whenreadingavalue,alwayslookstraightatthegraduations.6.Handlingafteruse:Completelywipeawayanywaterandoil.Lightlyapplyathincoatingofanti-corrosionoilandletdrybeforestorage.7.Notesonstorage:•Avoiddirectsunlight,hightemperatures,lowtemperatures,andhighhumidityduringstorage.•Ifadigitalheightgagewillnotbeusedformorethanthreemonths,•Ifaprotectivecoverisprovided,usethecoverduringstoragetopreventremovethebatterybeforestorage.dustfromadheringtothecolumn.05-18
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