OpenConeStyle PrecisionBenchLathes (PreloadedBallBearingSpindleConstruction) Provencompletel ysuccessfulwithourvariousenclosedheadmachines,theHardingepreloadedball bearingspindleconstructionisnowofferedintheopenconestyle. Comments,verbalandwritten,verifytheperformancefeaturestobeexpectedfromHardingepreloaded ballbearingspindleconstruction- seeinsidepages fordetails. Theextremeaccuracyandhighspindlespeedsobtainedwiththesemachinesmeangreaterproduction andlowercost. EQUIPMENT OB 37CataractBenchLatheComplete 013 47CataractBenchLatheComplete OB 49CataractBenchLatheComplete Ol3 57CataractBenchLatheComplete OB 59CataractBenchLatheComplete NETWEIGHT _ 32"BedI36"Bed 144lbs.158lbs. 146 lbs. 1160lbs. 155lbs.169lbs. .. I148lbs.162lbs. 157lbs.171lbs. RegularEquipment:Headstockwi t hDrawSpindle,Dri\-ePl ateand1\faleCenter; Ta il st ockwi th:11aleCen ter;32"or:3 ()"Bedwi t hToolPan,BedBolt,B ench Bolts,andnecess arywrenches .CompoundSlideHestandT -Restextra . - ----SPECIFICATIONS OB37OB47OB49OB57 - - - -CapacitythroughColletsandDrawSpindlel;:lin. %in.%in.1 in. SwingOverBed.....7in.7in.9in.7in. ColletUsed- DimensionsinColletBulletin3CHARDI NGE 4C HARDINGE4CHARDINCE5CHARDINCE MaximumDi stanceBetweenCenterswith32"Bed13in. 13in.13in.13 in. MaximumDistanceBetweenCenterswith36"Bed17in.17 in.l7in.17 in. RecommendedHighSpindleSpeed,R.P.M.3000300030003000 Capacity of Spindle with Three and Four Jaw Chuck3%4m.Ysin.Ysin.1 %2in. DiameterofStepsonHeadstockCone 2%3%4% in.2%3%4% in.2%4%6 in.2%3%4% in. WidthofBelt1%in.1lf4in.1%in.1%in. TravelofTailstockSpindle 3l;:lin.3l;:lin.3l;:lin.3l;:lin. - - -- ---OB59 1 in. 9in. 5CHARDINGE 13 in. 17 in. 3000 1 %2in. 2%4%6 in. 1%in. 3l;:lin. HARDINGEBROTHERS!>INC.!>ELMIRA!>N.Y. CHICAGO- NEWYORK- DETROIT- HARTFORD- PHILADELPHIA- CLEVELAND HARDINGE NEWYORK H ardingePrecisionPreloadedBallBearingHeadstock CROSSSECTIONOFHARDINGEOPENCONEHEADSTOCKWITHPRELOADEDBALLBEARI:-IGS THEterms"PrecisionBenchLathe"and"SpeedLathe"havealwaysbeenusedwhenreferringtoabench lathe. Therefore,thetwoessentialrequirementsareaccuracyandspeed.Toobtainaccuracywithplainbear-ingsrequiresaclosespindlefitwhichlimitsthespeedbecauseofthefrictiondevelopingexcessiveheatdetri mentaltothebearings. SuperprecisionDuplexBallBearingswithpreloading,asdescribedinthisbulletin,provideextremeaccuracy andhighspindlespeedswiththebearingsrequiringnoadjustment.Thedesirableresultsaresosurprisingthat actualuseisthebestmediumtodeterminetheadvantagesoveryourpresentmachines. HEADSTOCK:Theheadstockframeisofthefinest grade,seasonedandheat-treatedalloyironandhasa handscrapedbearingsurfacetofitthewaysofour amplyproportionedlathebed. TheoutstandingfeatureistheHardingepreloaded ballbearingspindleconstruction.Thedesignhasbeen verysuccess ulwithourenclosedheadmachinesover anumberofyears.Theprovenperformanceassures, First,greateraccuracy;Second;heaviercuts;Third, higherspindlespeeds. Thebearingsrequirenoattentionoradjustmentfor continualcare-freeoperation - thisimportantchar-acteristicovercomesexpensivedelayspreviouslyas-sociatedwithrepairoradjustmentofconventional sleevebearings. Thespindleishardenedandground,bothinternal! y andexternally,andismadeofthebestgradeball bearingsteel.Withtheballbearingconstruction,the spindleismountedinrotatingmemberstoeliminate wearonthespindle - anunusualfeatureforabench lathe.Thespindleconepulleyisprovidedwithfour holesforlockingandsixtyholesforindexing.The spindlehastheHARDINGEpatenttapernose- thread-ednosespindlefurnisheduponapplication. BALLBEARINGS:Workloadonasleevebearing issupportedbyafilmofoil ,thefunctioningofwhich isdependentuponsuchvariablefactorsasfilmthick-ness,temperatureanddifferenceinthegradesofoil used.Withapreloadedballbearing,thepressure betweenballsandracesissuchastoprevent forma tionofanoilfilmandthecontactofloadcarrying membersispositivelymetal tometal.Inotherwords, theloadiscarriedonperfectspheresofhardened steelinsteadofglobulesofoilwhoseload-carrying abilityvarieswiththeoperatingtemperature.Natur-ally,accuracywithspeedandlonglifeisattained. Thepreloadingisdescribedseparatelyandtbere sultantload-carryingcapacityisnotamatterofex-periment,butissubjecttoasaccurateamathematical determinationasisthestrengthofasteelbridge. Thesteelball,becauseofitsshape,presentsauniform andcalculableresistance.Theballsautomaticallyad justthemselvestotheproperangleforeitherpurely endorradialthrust,oracombinationofthetwo. Propersteel ,vastimprovementinmanufacturing methodsandtheuseofopticalgaugeshaveachieved auniformstandardofaccuracy,consideredcommer-ciallyimpossibleafewyearsago. HARDINGPRECISIONBALLBEARINGBENCHLATHESAREOFFEREDINFIVESIZES- REFERTOPAGEOBONE PageOB-Two HARDINGEBROTHERS,Inc.,ELMIRA,NEWYORK PRELOADING:Theterm"preloading"maybebest understoodbyreferringtotheaccompanyingillustra-tions:FigurelshowstheDuplexDoubleRowBear-ing beforeclamping.Theclearancebetweentheinner ringsatpoint"B"iscalculatedbythebearingmanu-facturertoproduceapre-determinedinitialloadfor benchlathepurposes. FIGURE1FIGURE2 Ourinstallationmerelyconsistsofturning thelocking nut"A"showninthecrosssectiononpageOB-Two untiltheinnerraces meet(SeeFigure 2).Thissimple assemblyprocedureautomaticall ysecurestheproper initialloadforcorrectspindlerigidityandrequires nofurtherattention.Thedottedlineindicateshow thepreloadpressuretakesplacethroughthebearing. Withtheangular races,theballshaveanangularcon-t