CHESTER Craftsman User manual
Contents
1. Introduction 2
2. Health&Safety 35
3. MachineSpecification 6
4. InstallationPlans 7
5. GeneralDimension 8
6. MetalCuttingProcess
a.Introduction
b.CentreLathe
c.CuttingTools
d.BasicTheory
e.ToolAngles
f. ToolMaterial
g.MaterialCommonUse
h.ToolLife
i. ChipForm./Breaker
j. CuttingSpeed/Feed
k.CuttingFluid/Lubric.
l. ScrewCutting
9
10
11
12
1314
15
16
17
1819
20
21
22
7. Conclusion 23
8. Parts
a.BedAssembly
b.HeadstockAssembly
c.GearboxAssembly
d.ApronAssembly
e.SaddleAssembly
f. ToolPostAssembly
g.TailstockAssembly
h.ControlRodAssembly
i. H’stockCoverAss’bly
j. ElectricSys.Assembly
k.FollowRestAssembly
l. SteadyRestAssembly
2425
2629
3032
3335
3637
3839
4041
4243
4445
4647
4849
5051
ChesterUKCraftsmanLathe
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Introduction
ChesterUKLimitedisaspecialistcompanythathasbeensupplyingthemachinetoolindustryforover15
years. The Chester UK Head Office comprises of a 30,500 sq.ft factory complete with offices and a
showroom. Specialising in conventional machine tools, Chester has built a reputation for quality and
reliability,whichishighlyregardedinthemachinetoolindustryandthemodelengineeringmarket.
Thereareseveraldivisions withinthe company;Export,Education, ModelEngineering&UKSales,all
withdedicatedsalespersonnelwhoaretrainedtoansweryourquestions.
When buying from Chester you can be assured of a complete backup service with mechanical and
electricalengineersthatareavailabletogiveadviceifrequired.
StockisalargepartofanybusinessandChesterhavealwaysinvestedsubstantiallyinbuildingalarge
quantity of machines and spares, ready to satisfy customer requirements. Chester UK has one of the
largest stocks ofconventional new machines and accessories within Great Britain. Pleasetake time to
visitourwebsite: www.chesteruk.net
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Health&Safety
Aswithallmachinerytherearecertainhazardsinvolvedwiththeoperationanduseofthelathe.Using
themachinewithrespectandcautionwillconsiderablylessenthepossibilityofpersoninjury.However,if
normalsafetyprecautionsareoverlookedorignored,personalinjurytotheoperatormayresult.
Thismachinewasdesignedforcertainapplicationsonly.Westronglyrecommendthatthemachineisnot
modified,and/orusedforanyapplicationotherthanwhichitwasdesigned.Ifyouhaveanyquestions
relativetoitsapplicationdonotusethemachine,untilyouhavefirstbeenincontactwithChester
UK.
The lathe may not arrive with a power socket or plug. In the event of this happening, please inform
ChesterUKonTel:(01244)531631.
Safetyrulesforalltools
User
1. Wearcorrectapparel
Noloose clothing,gloves,rings,braceletsorotherjewellerytogetcaughtinmovingparts.Non
slipfootwearisrecommended.Wearprotectivehaircoveringtocontainlonghair.
2. Alwaysweareyeprotection
Refer to ANSLZ87.1 standard for appropriate recommendations. Also use face and / or a dust
maskifthecuttingoperationisdusty.
3. Don’toverreach
Keepaproperfootingandbalanceatalltimes.
4. Neverstandonatool
Seriousinjurycouldoccurifthetoolistippedorifthecuttingtoolisaccidentallycontacted.
5. Neverleavethetoolrunningunattended
Turnpoweroff.Leavetooluntilitcomestoacompletestop.
6. Drugs,alcoholandmedication
Donotoperatethetoolwhileundertheinfluenceofdrugs,alcoholoranymedication.
7. Makesurethetoolisdisconnectedfromthepowersupply
Whilemotorisbeingmounted,connectedorreconnected.
8. Always
Keephandsandfingersawayfromanymovingparts.
9. Stop
Themachinebeforemovingchips.
10.Shutoff
Powerandcleanthelatheandworkareabeforeleavingthemachine.
Useofthemachine
1. Removeadjustingkeysandwrenches
Form a habit of checking to see that keys and adjusting wrenches are removed from the tool
beforeturningit‘on’.
2. Don’tforcethetool
Itwilldothejobbetterandbesaferattherateforwhichitwasdesigned.
3. Usetherighttool
Don’tforcethetoolorattachmenttodoajobforwhichitwasnotdesigned.
4. Securework
Useclampsoravicetoholdworkwhenpractical.It’ssaferthanusingyourhands,andfreesboth
tooperatethemachine.
ChesterUKCraftsmanLathe
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5. Maintaintoolsintopcondition
Keeptoolssharpandcleanforthebestandsafestperformance.Followinstructionsforlubricating
andchangingaccessories.
6. Userecommendedaccessories
ConsultChesterUKforrecommendedaccessories.Theuseofimproperaccessoriesmaycause
hazards.
7. Avoidaccidentalstarting
Makesuretheswitchisinthe‘OFF’positionbeforeplugginginpowercord.
8. Stop
Themachinebeforeputtingmaterialinthevice.
9. Always
Havestockfirmlyclampedinthevicebeforestartingthecut.
10. Groundalltools
If the tool is equipped with a threeprong plug, it should be plugged into a threehole electrical
receptacle.Ifanadapterisusedtoaccommodateatwoprongreceptacle,theadapterplugmust
beattachedtoaknownground.Neverremovethethirdprong.
Adjustment
Make all adjustments with the power off.When assembling follow the manuals instructions, this
willensurecorrectinstructionandasafestructure.
Workingenvironment
1. Keeptheworkareaclean
Clutteredareasandbenchesinviteaccidents.
2. Don’tuseinadangerousenvironment
Don’tusepowertoolsindamporwetlocations,orexposetorain.Keeptheworkareawelllit.
3. Keepchildrenetcatasafedistance.
Allchildrenetcshouldbekeptatasafedistancefrom theworkarea.
4. Don’t
Install&usethismachineinanexplosivedangerousenvironment.
Maintenance
1. Disconnect
Machinefromthepowersourcewhenmakingrepairs.
2. Checkdamagedparts
Beforefurtheruseofthetool,aguardorotherpartthatisdamagedshouldbecarefullycheckedto
ensure that it would operate properly and perform its intended function check for alignment of
movingparts,bindingofmovingparts,breakageofparts,mountingandanyotherconditionsthat
may affect its operation. A guard or other part that is damaged should be properly repaired or
replaced.
3. Disconnecttools
Beforeservicingandwhenchangingaccessoriessuchasbladesbits,cutters,etc.
4. Toprevent
Thecorrosionofmachinedsurfaceswhenasolubleisusedascoolant,payparticularattentionto
wipingdrythesurfaceswherefluidaccumulatesanddoesnotevaporatequickly,suchasbetween
themachinebedandvice.
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SafetyDevice
1. Interlockswitchonpulleycover.Assoonasthepulleycoverisopen,themachinewillcometo
a stop with the function of this switch. Do not remove this switch from the machine for any
reason,andcheckit’sfunctionfrequently.
2. Interlockswitchoncuttingarea.Assoonasthepulleycoverisopen,themachinewillcometo
a stop with the function of this switch. Do not remove this switch from the machine for any
reason,andcheckit’sfunctionfrequently.
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MachineSpecification
SwingOverBed 300mm 12"
SwingOverCrossSlide 200mm 8"
SwinginGap 450mm 18"
DistanceBetweenCentres 570mm 23"
HoleThroughSpindle 36mm
SpindleMount 2¼"x8TPI
SpindleTaper(WithSleeve) MT5(MT3)
NumberofSpindleSpeeds(withBackgear) 12
RangeofSpindleSpeeds 501200
LowGear
50/75/100/120/165/220
HighGear300/410/550/655/900/1200
FeedRange 0.120.42mm/rev
NumberofInchThreads: 40
RangeofInchThreads 4112TPI
NumberofMetricThreads: 27
RangeofMetricThreads 0.257.5mm
MaxToolSize: 16mm 5/8"
CompoundSlideTravel 100mm 4"
CrossSlideTravel: 150mm 6"
CarriageTravel: 440mm 17"
TailstockSpindleTravel: 100mm 4"
TaperinTailstockSpindle: MT3
WidthofBed: 190mm 8"
OverallDimensionswithStand(LxWxH): 1370x740x1233mm
MainMotor: 1½HP,240Vor415V
NetWeight: 390Kg
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InstallationPlans
Machinetostand
Machinetofloor
1.CraftsmanLathe
2.Tray
3.Stand
4.Adjustableironspacer
5.Foundationbolt
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GeneralDimension
Frontview
Topview
A717mm
B 1310mm
C 610mm
D 1400mm
E 1310mm
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MetalCuttingProcess–Turning
Introduction
This training guide is designed to give you 'handson' experience through which you can gain a good
appreciationofthiswellknowntypeofmachinetool.Inparticularyourattentionwillbedirectedtowards
itsoperationalusesandparameters,thegenerallayoutofcontrols,accessories,associatedtooling,and
themaintenancefactorsrelatedtolathes.
Inorderthatyoucanmakethemostuseofthelimitedtimeavailableonlathesitisessentialthatyouuse
everychancetoconsolidatewhatyouobserve.Thistypeofworkislargelyselfmotivatedandthedrive
anddesiretofindoutmustcomefromyou.
Ittakesaconsiderabletimetobecomeaskilledlatheoperatorandtopossessalltheskillofhandthat
goeswithit.Thereforeitisnotexpectedthatyouwillbemanuallyskilledoncompletionofthemodulebut
youwillhavegainedintellectuallyandwithoutdoubt,bypracticalinvolvement,someskillofhandwillbe
achieved.
Figure1.ExampleofaTypicalCentreLathe
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CentreLathe
The term Centre Latheis derived from the fact that inits operation the lathe holds apiece of material
betweentworigidsupportscalledcentres,orbysomeotherdevicesuchasachuckorfaceplatewhich
revolvesaboutthecentrelineofthelathe.
Thelatheshownaboveisatypicalexample.Thismachineisusuallyusedinajobbing(oneoff)situation
orforsmallbatchworkwhereitwouldbetooexpensivetospecially'toolup'forjustafewitems.
Thelatheonwhichyouwillworkisamachineusedtocutmetal.Thespindlecarryingtheworkisrotated
whilstacuttingtool,whichissupportedinatoolpost,ismadetotravelinacertaindirectiondepending
on the form of surface required. If the tool moves parallel to the axis of the rotation of the work a
cylindricalsurfaceisproducedasinFig2(a),whilstifitmovesatrightanglestothisaxisitproducesa
flatsurfaceasinFig2(b).
Figure2a.Producinga
CylindricalSurface Figure2b.ProducingaFlatSurface
ThelathecanalsobeusedforthepurposesshowninFig2c,2d,2eand2f.
Figure2c.TaperTurning Figure2d.PartingOff/UnderCutting
Figure2e.RadiusTurningAttachment Figure2f.DrillingonaLathe
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CuttingTools
Thetoolusedinalatheisknownasasinglepointcuttingtool.Ithasonecuttingedgeorpointwhereasa
drillhastwocuttingedgesandafilehasnumerouspointsorteeth.
The lathe tool shears the metal rather than cuts as will be seen later and it can only do so if there is
relative motion between the tool and the work piece. For example, the work is rotating and the tool is
movedintoitspathsuchthatitformsanobstructionandshearingtakesplace.Ofcoursetheamountof
movementisofparamountimportance toomuchatonce couldforinstanceresultinbreakageofthe
tool.
Figure3.TypesofCuttingTool
The type and design of the tools selected will depend on the job in hand, the machining operation
selectedandthematerialtobecut.Thecorrecttoolespeciallythevariousfaceanglesareessentialifthe
operation isto be done in a costeffective (i.e. productive) way. The tools used in a lathe are various,
someofwhichareshowninfigure3.
The range of cutting tool types is extensive and a few examples only are shown in this handout.
Nonethelessyoushouldtakeeveryopportunitytolookdeeperintothetypesoftoolsavailable.
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BasicTheory
Theusualconceptionofcuttingsuggestsclearingthesubstanceapartwithathinknifeorwedge.When
metaliscuttheactionisratherdifferentandalthoughthetoolwillalwaysbewedgeshapedinthecutting
area and the cutting edge should always be sharp the wedge angle will be far too great for it to be
consideredknifeshaped.Consequentlyashearingactiontakesplacewhentheworkmovesagainstthe
tool.
Figure4.BasicMetalCuttingTheory
Figure 4 shows a tool being moved against a fixed work piece. When the cut is in progress the chip
pressesheavilyonthetopfaceofthetoolandcontinuousshearingtakesplaceacrosstheshearplane
AB.AlthoughtheFigureshowsatoolworkinginthehorizontalplanewiththeworkpiecestationary,the
sameactiontakesplacewiththeworkpiecerevolvingandthetoolstationary.
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ToolAngles
There are three important angles in the construction of a cutting tool rake angle, clearance angle and
planapproachangle.
Figure5.MainFeaturesofaSinglePointCuttingTool
RakeAngle
Rakeangleistheanglebetweenthetopfaceofthetoolandthenormaltotheworksurfaceatthecutting
edge. In general, thelarger the rake angle, the smaller the cutting force on the tool, since for a given
depth of cut the shear plane AB, shown inFigure 4 decreases as rake angle increases. A large rake
angle will improve cutting action, but would lead to early tool failure, since the tool wedge angle is
relatively weak. A compromise must therefore be made between adequate strength and good cutting
action.
MetalBeingCutCastIron HardSteel/
Brass
Medium
CarbonSteel MildSteel Aluminium
TopRakeAngle 0° 8° 14° 20° 40°
Table1.Typicalvaluefortoprakeangle
ClearanceAngle
Clearanceangleistheanglebetweentheflankorfrontfaceofthetoolandatangenttotheworksurface
originating at the cutting edge. All cutting tools must have clearance to allow cutting to take place.
Clearanceshouldbekepttoaminimum,asexcessiveclearanceanglewillnotimprovecuttingefficiency
andwillmerelyweakenthetool.Typicalvalueforfrontclearanceangleis6°inexternalturning.
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PlanProfileofTool
Theplanshapeofthetoolisoftendictatedbytheshapeofthework,butitalsohasaneffectonthetool
lifeandthecuttingprocess.Figure6showstwotools,onewhereasquareedgeisdesiredandtheother
wherethestepsintheworkendwithachamferorangle.Thediagramshowsthat,forthesamedepthof
cut,theangledtoolhasamuchgreaterlengthofcuttingedgeincontactwiththeworkandthustheload
perunitlengthoftheedgeisreduced.Theangleatwhichtheedgeapproachestheworkshouldintheory
be as large as possible, but if too large, chatter may occur. This angle, known as thePlan Approach
Angle,shouldthereforebeaslargeaspossiblewithoutcausingchatter.
Figure6.PlanApproachAngle
The trailing edge of the tool is ground backwards to give clearance and prevent rubbing and a good
generalguideistogrindthetrailingedgeat90°tothecuttingedge.ThustheTrailAngleorReliefAngle
willdependupontheapproachangle.
Asmallnose radius onthetoolimprovesthe cuttingandreducestoolwear.If asharppointisusedit
givespoorfinishandwearsrapidly.
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CharacteristicsofToolMaterial
Forefficientcuttingatoolmusthavethefollowingproperties:
HotHardness
Thismeanstheabilitytoretainitshardnessathightemperatures.Allcuttingoperations
generateheat,whichwillaffectthetoolshardnessandeventuallyitsabilitytocut.
StrengthandResistancetoShock
Atthestartofacutthefirstbiteofthetoolintotheworkresultsinconsiderableshock
loadingonthetool.Itmustobviouslybestrongenoughtowithstandit.
LowCoefficientofFriction
The toolrubbing against theworkpieceandthechiprubbingon thetopfaceofthetoolproduceheat,
whichmustbekepttoaminimum.
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ToolMaterialsinCommonUse
HighCarbonSteel
Contains 1 1.4% carbon with some addition of chromium and tungsten to improve wear
resistance.Thesteelbeginstoloseitshardnessatabout250°C,andisnotfavouredformodern
machiningoperationswherehighspeedsandheavycutsareusuallyemployed.
HighSpeedSteel(H.S.S.)
Steel, which has a hot hardness value of about 600° C, possesses good strength and shock
resistantproperties.Itiscommonlyusedforsinglepointlathecuttingtoolsandmultipointcutting
toolssuchasdrills,reamersandmillingcutters.
CementedCarbides
An extremely hard material made from tungsten powder. Carbide tools are usually used in the
formofbrazedorclampedtips.Highcuttingspeedsmaybeusedandmaterialsdifficulttocutwith
HSSmaybereadilymachinedusingcarbidetippedtool.
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ToolLife
Asageneralruletherelationshipbetweenthetoollifeandcuttingspeedis
VTn=C
where;
V=cuttingspeedinm/min
T=toollifeinmin
C=aconstant
ForhighspeedsteeltoolsthevalueofCrangesfrom0.14to0.1andforcarbidetoolsthevaluewouldbe
0.2.
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ChipFormation&ChipBreaker
The type of chip produced depends on the material being machined and the cutting conditions at the
time.Theseconditionsincludethetypeoftoolusedtool,rateofcuttingconditionofthemachineandthe
useorabsenceofacuttingfluid.
ContinuousChip
This leaves thetool asalongribbonandiscommon whencutting most ductile materialssuch asmild
steel,copperandAluminium.Itisassociatedwithgoodtoolangles,correctspeedsandfeeds,andthe
useofcuttingfluid.
Figure7.ContinuousChip
DiscontinuousChip
Thechipleavesthetoolassmallsegmentsofmetalresultedfromcuttingbrittlemetalssuchascastiron
andcastbrasswithtoolshavingsmallrakeangles.Thereisnothingwrongwiththistypeofchipinthese
circumstances.
Figure8.DiscontinuousChip
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ContinuousChipwithBuiltupEdge
Thisisachiptobeavoidedandiscausedbysmallparticlesfromtheworkpiecebecomingweldedtothe
toolfaceunderhighpressureandheat.Thephenomenonresultsinapoorfinishanddamagetothetool.
It can be minimised or prevented by using light cuts at higher speeds with an appropriate cutting
lubricant.
Figure9.ContinuousChipwith
BuildupEdge
ChipBreaker
Achipbreakerisusedtobreakthecontinuouschipintosectionssothatthechipscannottanglearound
thecuttingtool.Grindingagrooveonthetoolfaceafewmillimetersbehindthecuttingedgemakesthe
simplestformofchipbreaker.
ChesterUKCraftsmanLathe
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