CHESTER U.K. Cobra User manual

CobraLathe
InstructionManual
ChesterUKLtd
ClwydClose,HawardenIndustrialPk
Hawarden,NrChester
Flintshire.CH53PZ
Tel:01244531631
Email:[e-mail]
www.chesteruk.net

Contents
1. Introduction 2
2. Health&Safety 35
3. MachineSpecification 6
4. Testing 7
5. Operation 816
6. Maintenance 17
7. OilingPoints 18
8. ChangeGearTable 19
9. PartsList&Diagrams 2025
10.WiringDiagrams 2627
11.CEDocument 28
ChesterUKCobraLathe
1

Introduction
ChesterUKLimitedisaspecialistcompanythathasbeensupplyingthemachinetoolindustryfor
over15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,whichishighlyregardedinthemachinetoolindustryandthemodelengineeringmarket.
Thereareseveraldivisionswithin thecompany;Export, Education,ModelEngineering&UKSales,all
withdedicatedsalespersonnelwhoaretrainedtoansweryourquestions.
When buying from Chester you can be assured of a complete backup service with mechanical and
electricalengineersthatareavailabletogiveadviceifrequired.
StockisalargepartofanybusinessandChesterhavealwaysinvestedsubstantiallyinbuildingalarge
quantity of machines and spares, ready to satisfy customer requirements. Chester UK has one of the
largest stocks ofconventional new machinesand accessories within Great Britain. Please taketime to
visitourwebsite: www.chesteruk.net
ChesterUKCobraLathe
2

Health&Safety
Aswithallmachinerytherearecertainhazardsinvolvedwiththeoperationanduseofthelathe.
Using the machine with respect and caution will considerably lessen the possibility of person injury.
However, if normal safety precautions are overlooked or ignored, personal injury to the operator may
result.
Thismachinewasdesignedforcertainapplicationsonly.Westronglyrecommendthatthemachineisnot
modified,and/orusedforanyapplicationotherthanwhichitwasdesigned.Ifyouhaveanyquestions
relativetoitsapplicationdonotusethemachine,untilyouhavefirstbeenincontactwithChester
UK.
The lathe may not arrive with a power socket or plug. In the event of this happening, please inform
ChesterUKonTel:(01244)531631.
Safetyrulesforalltools
User
1. Wearcorrectapparel
Nolooseclothing,gloves,rings,braceletsorotherjewellerytogetcaughtinmovingparts.Non
slipfootwearisrecommended.Wearprotectivehaircoveringtocontainlonghair.
2. Alwaysweareyeprotection
Refer to ANSLZ87.1 standard for appropriate recommendations. Also use face and / or a dust
maskifthecuttingoperationisdusty.
3. Don’toverreach
Keepaproperfootingandbalanceatalltimes.
4. Neverstandonatool
Seriousinjurycouldoccurifthetoolistippedorifthecuttingtoolisaccidentallycontacted.
5. Neverleavethetoolrunningunattended
Turnpoweroff.Leavetooluntilitcomestoacompletestop.
6. Drugs,alcoholandmedication
Donotoperatethetoolwhileundertheinfluenceofdrugs,alcoholoranymedication.
7. Makesurethetoolisdisconnectedfromthepowersupply
Whilemotorisbeingmounted,connectedorreconnected.
8. Always
Keephandsandfingersawayfromanymovingparts.
9. Stop
Themachinebeforemovingchips.
10.Shutoff
Powerandcleanthelatheandworkareabeforeleavingthemachine.
Useofthemachine
1. Removeadjustingkeysandwrenches
Form a habit of checking to see that keys and adjusting wrenches are removed from the tool
beforeturningit‘on’.
2. Don’tforcethetool
Itwilldothejobbetterandbesaferattherateforwhichitwasdesigned.
3. Usetherighttool
Don’tforcethetoolorattachmenttodoajobforwhichitwasnotdesigned.
4. Securework
Useclampsoravicetoholdworkwhenpractical.It’ssaferthanusingyourhands,andfreesboth
tooperatethemachine.
ChesterUKCobraLathe
3

5. Maintaintoolsintopcondition
Keeptoolssharpandcleanforthebestandsafestperformance.Followinstructionsforlubricating
andchangingaccessories.
6. Userecommendedaccessories
ConsultChesterUKforrecommendedaccessories.Theuseofimproperaccessoriesmaycause
hazards.
7. Avoidaccidentalstarting
Makesuretheswitchisinthe‘OFF’positionbeforeplugginginpowercord.
8. Stop
Themachinebeforeputtingmaterialinthevice.
9. Always
Havestockfirmlyclampedinthevicebeforestartingthecut.
10. Groundalltools
If the tool is equipped with a threeprong plug, it should be plugged into a threehole electrical
receptacle.Ifanadapterisusedtoaccommodateatwoprongreceptacle,theadapterplugmust
beattachedtoaknownground.Neverremovethethirdprong.
Adjustment
Make all adjustments with the power off. When assembling follow the manuals instructions, this
willensurecorrectinstructionandasafestructure.
Workingenvironment
1. Keeptheworkareaclean
Clutteredareasandbenchesinviteaccidents.
2. Don’tuseinadangerousenvironment
Don’tusepowertoolsindamporwetlocations,orexposetorain.Keeptheworkareawelllit.
3. Keepchildrenetcatasafedistance.
Allchildrenetcshouldbekeptatasafedistancefromtheworkarea.
4. Don’t
Install&usethismachineinanexplosivedangerousenvironment.
Maintenance
1. Disconnect
Machinefromthepowersourcewhenmakingrepairs.
2. Checkdamagedparts
Beforefurtheruseofthetool,aguardorotherpartthatisdamagedshouldbecarefullycheckedto
ensure that it would operate properly and perform its intended function check for alignment of
movingparts,bindingofmovingparts,breakageofparts,mountingandanyotherconditionsthat
may affect its operation. A guard or other part that is damaged should be properly repaired or
replaced.
3. Disconnecttools
Beforeservicingandwhenchangingaccessoriessuchasbladesbits,cutters,etc.
4. Toprevent
Thecorrosionofmachinedsurfaceswhenasolubleisusedascoolant,payparticularattentionto
wipingdrythesurfaceswherefluidaccumulatesanddoesnotevaporatequickly,suchasbetween
themachinebedandvice.
ChesterUKCobraLathe
4

SafetyDevice
1. Interlockswitchonpulleycover.Assoonasthepulleycoverisopen,themachinewillcometo
a stop with the function of this switch. Do not remove this switch from the machine for any
reason,andcheckit’sfunctionfrequently.
2. Interlockswitchoncuttingarea.Assoonasthepulleycoverisopen,themachinewillcometo
a stop with the function of this switch. Do not remove this switch from the machine for any
reason,andcheckit’sfunctionfrequently.
ChesterUKCobraLathe
5

MachineSpecification
DrillingCapacity 10mm
EndMillCapacity 10mm
FaceMillCapacity 20mm
SpindleStroke 30mm
Throat 140mm
TableWorkingSurface 50x145mm
LongitudinalTravel 180mm
CrossTravel 90mm
Max.DistanceSpindleToTable 220mm
No.OfSpindleSpeeds Variable
RangeOfSpeeds 1002000rpm
SpindleTaper MT2
Motor 150W
Supply 240V50Hz
Weight(nw/gw) 47/60Kg
Dimensions(LxWxH) 540x380x680mm
ChesterUKCobraLathe
6

Testing
Whenthelatheismountedtoyoursatisfaction,proceedasfollows:
a) Closethechuckjaws.
b) Checkthetailstockis‘nipped’andthebarrellockistightened.
c) Checkalllooseitemsareremovedfromthelathe.
d) Setthesaddleapproximatelymidwayalongthebed.
e) PresstheEmergencyStopButtonIN(EmergencyStopON).
f) ChecktheAutofeed/ManualLeverissettomanual(Handlogo).
g) Closethechuckguard.
h) CheckthespeedcontrolisswitchedOFF(fullyanticlockwise).
i) ChecktheForward/Off/ReverseSwitchisintheOFFposition.
j) ConnectthemachinetothemainssupplyandswitchpowerON.
k) TurnEmergencyStopswitchtotherightandallowittospringoutandreset.
l) ChecktheGreenPowerLEDisilluminated.
m) TurntheSpeedControlSwitchOn(ClicksOn).
n) ChecktheAmberLED(FaultLight)isilluminated.
o) SwitchtheSpeedControlSwitchOFF(ClicksOFF)andtheAmberLEDisnowoff.
p) SelectForwardontheForward/Off/Reverseswitch.
q) TurntheSpeedControlSwitchOnandadvanceuntiltheChuckstartstorotate.
r) LifttheChuckGuard;checkthespindlestopsandtheAmberfaultLEDilluminates.
s) ResettheChuckGuard,checkthespindledoesNOTrestartandtheAmberfaultLEDremains
On.
t) TurntheSpeedControlSwitchOFF,andthattheAmberLEDgoesoff.
u) TurntheSpeedControlSwitchON,advanceuntilthespindlestartstorotate.
v) Overaperiodofapproximately5minutesadvancethespeedinstagestomaximum,runat
maximumforatleast2minutes,checkthatthereisnothinguntoward(noexcessivevibration,
speedprogressionissmoothetc).
w) Ifalltheabovechecksarecorrect,stopthespindle;selecttheAutofeedfunction(ifnecessary
‘jog’theleadscrewhandletoenablethegearstomesh).Switchonandadvancetoa
reasonablespeed,checkthesaddledrivessmoothlytowardsthechuck.
x) Stopthespindle,selectreverse,switchONandadvancetoareasonablespeed,checkthe
chuckdrivessmoothlytowardsthetailstock.
y) Ifalltheabovechecksarecorrect,thefinalcheckistosetthespindlerunning,thenhitthe
EmergencyStopswitch.CheckthespindlestopsandallpowerindicationsgoOFF.
z) Yourlatheisnowreadyforuse.Enjoy.
ChesterUKCobraLathe
7

Operation
Definitions
MainAxis
Thisistheaxisestablishedthroughthespindleoftheheadstock.Itishorizontaltoandparallelwiththe
lathebedalongitslength,asdescribedbythesaddle
WorkAxis
This is the axis established by the work piece;it is horizontal to, but not necessarily parallel with, the
lathebed,alongitslength.
TraverseAxis
Thisistheaxisdescribedbythetraverseslidewhenitisbeingmovedindependentlyofthesaddle.Itis
perpendiculartothemainaxisinthehorizontalplane.
CompoundAxis
Thisistheaxisdescribedbythecompoundslide,iffitted,whenitisbeingoperatedindependentlyofthe
traverseslideandthesaddle.
Headstock
The‘engineblock’ofthelathe,supportsthemotor,thespindle,andthecoverforthechangegears,the
drive belt and the driven end of the leadscrew. It also mounts the control panel for the motor and the
selectorfortheleadscrew.
ChangeGearCover
Protectivecover,enclosingthemotorpulley,thedrivepulley&drivebeltandthechangegear.
Motor
220Vd.c.motor.
MountingFlange
The mountingflangeisintegralwith thespindle andmountsallthematerialcarriers(chucks,faceplate
etc), it is bored with a No.2 morse taper to accept the headstock centre. The boring is then carried
through the complete length of the spindle (10.5mm clear) to allow long lengths of round bar to be
machined. Your MicroLathe is supplied with a chuck adaptor plate and chuck already fitted to the
mountingflange.
ChuckSafetyCover
Aclearacetatecovermountedonapivotbaronthereartopfrontfaceoftheheadstock.Itcanbetipped
out of the way to access the chuck when it is stationary, and repositioned over the chuck during
operation.Itissafetyinterlocked,ifitisnotinpositionthemotorwillnotrun,orthemotorwillstopifitis
movedwhilstthespindleisturning.
MotorControlPanel
PowerOnLED
GreenLEDthatindicatesthatpowerisavailabletothemotor.i.e.mainsisapplied,fuseisintact
andtheEmergencyStopswitchisnotactivated.
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FaultLED(markedUNNORMAL)
Amber LED that indicates that there is a fault or an incorrect control sequence. e.g. the chuck
guard interlock has been activated or the speed control is activated without forward or reverse
directionbeingselected.TheMotorwillnotrunifthefaultLEDisilluminated.Ifthesafetyinterlock
is activated, if the safety interlock will remain in force until the interlock is reset and the start
sequenceisreinitiated.
FuseCap
Accesscapforthe20mmfusecartridge(1Amp250V).
SpeedControlKnob
Roundraisedridgeknobconnectedtothecircuitthatcontrolsthemotorspeed(1002000rpm).
Forward/Off/ReverseSwitch
Three position switch that controls the direction of the rotation of the spindle. Forward indicates
that the spindle is turning toward the operator; Reverse, the spindle is turning away from the
operator.ThecentreOffpositioninhibitsthespindlefromturningineitherdirection,undermotor
drive.
EmergencyStopSwitch
RedDomedMushroomswitch;ifpresseditremovesallpowertothemachine.Itisa ‘knockoff,
stayoff’switch.Toresettheswitchthedomedheadmustbeturnedclockwise,whichwillallowthe
switchtounlatchand‘springout’andresetitself.
ChesterUKCobraLathe
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(Chuck&safetycoverremovedforclarity)
ChesterUKCobraLathe
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LeadscrewSelector
Aroundcentreribswitch/lever,whichallowsselectionoftheleadscrewto‘Autofeed’,i.e.drivenbythe
changegeartrain(indicatedbyatriangularwaveformsign),ormanually,i.e.drivenbythehandleonthe
endoftheleadscrew(indicatedbya‘hand’logo).
LatheBed
Solid cast, machined bed. The face machining gives two flat bearing surfaces, whilst the ancillary
machininggivesadovetailformtothebed,andformsarigidstablelocatingandguidingsystemforall
themachinescomponents.
Saddle
Maincastingthatisprecisionmachinedtomarrywiththelathebed.Itmovesparalleltothemainaxis.It
mountsthetraverseslide.The‘gib’stripsetintherearofthesaddledovetailmaintainstheaccuracyof
thefitofthesaddletothebed.
TraverseSlide
Mountedona‘dovetail’landmachinedontothetopofthesaddle.The‘gib’stripsetintherighthandside
ofthetraversedovetailslidemaintainstheaccuracyofthefitoftheslide.Thebedofthetraversehastwo
‘T’slotsmachinedintoittoallowthemountingofthetoolpostorthecompoundslideaccessory.
TraverseSlideControl
Awheelandrodhandle,mountedonashaftthatisanchoredintoahousingmachinedinthefrontofthe
traverseslide,theshaftis threadedandis engagedina dogfixedtothesaddle,enablingthe traverse
slidetobedrivenbackandforthacrossthesaddleperpendiculartothemainaxis.Thereisagraduated
ring(thimble)ontheneckofthehandletoallowthemovementoftheslidetobemeasured.
ToolPost
A doublesided tool post. Each tool position has 2 securing bolts to clamp the tool in place. One tool
mountinghasafixed‘bed’theotherhasa‘rocking’bedinacurvedseatingtoallowthetooltobetilted
slightlyforwardorbacktoallowprecisetoolheightstobeachieved,withoutthenecessityforfineshims.
Thetoolpostissecuredintoeitheroneofthe‘T’slotkeeper.Thetoolpostisnotkeyedintothe‘T’slotso
itcanbeturnedtoanyanglebeforebeinglockedinposition.
ChesterUKCobraLathe
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ChesterUKCobraLathe
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GearChangeCoverKnob
Areededknobscrewedintothefrontoftheheadstock,itlocatesinaslotinthechangegearcover,and
isusedtosecurethecovertoallowittobesungopen.
Tailstock
Amachinedcastingthataccuratelyfitstothelathebed.Itcarriesthetailstockbarrel.Thetailstockbarrel
ismachinedwithaNo.1MT,whichallowstheaccessoriestobemounted(centres,drillchucks,reamers
etc).Thetailstockispositionedonthebedbyaclampmechanismatthefrontofthetailstockbody.The
twocapheadboltsinthefrontflangeofthecastingtightentheclamp.Thetailstockiscapableofbeing
offsettoallowfortaperturning.Theoffsetlockingscrewisontherightofthetailstock.
TailstockBarrelControl
Wheel androd handle that controls the backward and forward movement of the barrel in the tailstock.
Thebarrelhasatravelof22mm,toallowthetailstocktoolingtobebroughtintocontrolledcontactwith
theworkpiece;thisisindicatedona coarsescaleengravedonthebarrelitself.Thescaleindicates–0
andthen20plustwo(x1mm)divisions.Thesupplied tailstock centrewill self ejectat–0.Thetailstock
control has a graduated ring (thimble) mounted on the neck of the handle so that the amount of
movementcanbemeasured.
TailstockBarrelLock
Small‘petal’knobthatlocksthebarrelinplaceonceithasbeenmovedintotherequiredposition.
Leadscrew
Theleadscrewisathreadedshaftthatisanchoredintoahousingmachinedintotheendofthelathebed.
Theshaftrunsvirtuallythroughthecentreaxisoftheundersideofthebed,andisengagedinadogfixed
totheundersideofthesaddle,enablingthesaddletobedrivenbackandforthalongthemainaxisofthe
bed.Thefixeddogiswellsupportedfromthefrontapronofthesaddle,andcombinedwitheffectofthe
centralizedaxisoftheleadscrew,resultsinaverysmooth‘judder’freemovement.Theleadscrewcanbe
driven from either end, from the headstock end, via the change gear train, for auto feed and thread
cutting,ormanuallybytheleadscrewdrivehandle.
Note
The leadscrew is permanently engaged into the saddle dog. Any movement of the leadscrew is
transmittedtothesaddle.
LeadscrewDriveHandle
Wheel and rod handle locked onto the end of the leadscrew shaft. Turing the handle will turn the
leadscrewanddrivethesaddlebackandforthalongthemainaxisofthelathe.Thereisagraduatedring
(thimble)ontheneckofthehandletoallowthemovementofthesaddletobemeasured.
MotorSecuringBolts
Twocapheadboltsscrewthroughthechangegearcompartmentbulkheadandintothemotorflange.The
holesthroughthebulkheadareelongatedtoallowthemotortobemovedslightlytomaintainthedrive
belttension.
LeadscrewOilingPoint
Thisisasmallholesituatedbetweentwocapheadboltsonthelowerrightfaceofthesaddleapron.The
oil gallery gives direct access to the leadscrew dog, and enables oil to be spread onto the leadscrew
(whichismainlyobscuredbeneaththelathebed.)
MotorBrushCaps
Twobrushcapslocatedtopandbottomofthemotor;theyareaccessedbyremovingthesplashguard.
ChesterUKCobraLathe
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ChesterUKCobraLathe
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ChesterUKCobraLathe
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YourCobraLathehasbeenfactorysetandadjusted,however,duringitslifetimeyoumay
find occasion whereby the lathe needs adjusting to maintain its accuracy and optimum
performance.Theseadjustmentscanbemadeasfollows:
Saddle&TraverseSlideAdjustment
Thesaddleandthetraverseslidearemountedoverdovetailsections.Inordertomaintainthe‘tightness’
of the fit; between the sloping surface of the component and its matting surface a gib strip has been
inserted(Attherearofthesaddle,andtotherighthandsideofthetraverseslide).
Toadjustthegibstrips,loosenthelocknutsandscrewtheadjustingscrewIN(No.4forthetraverseslide
andNo.3forthesaddle).‘Nipping’thecomponenttighttoitsbedway.Tightenallthescrewstothesame
torque.Check,usingthefeedhandles,thatthesaddle/slidearelockedinplace.
Unscreweachadjustingscrewbyquarterturn,holdthescrew(socketgrubscrew)inpositionandtighten
the locknut. Check the component now moves smoothly along its bed, using the feed handles. If not,
carry outthesameprocedure,unscrewby athirdturnthistime,etc,ifthemovementwastootight;by
lessthanaquarteretc.,ifthemovementbecametoloose.
Repeattheprocedureuntilthemovementsaresmoothandtight.N.B.Alwaystightenthelocknutsbefore
testing.
FeedScales
The two thimbles that are mounted on the feed shafts of the leadscrew and the traverse feed should
move freely with the motion of the handle and not slip. The thimbles can be turned, using more force,
independently of the handle in order to set a predetermined start or finish point. If the thimbles are
‘slipping’i.e.notmaintainingtheirplacerelativetothehandle,whilstthehandleisturning;thecauseis
almostinevitablydirt,swarfetal.,betweenthepressureplateandthethimble.Torectifythis,undothe
nut and washer securing the handle to the shaft, remove the hand wheel, and then remove the keyed
collarandthimbleassembly.Takecarethatthekeydoesnotdropoutoftheshaft.Graduallyseparate
the thimble from the keyed collar; by twisting and turning, until there is sufficient space to clean the
matingsurfaces.
BE WARNED The friction drive between the collar and the thimble is effected by a wire spring
(likepartofacirclip)thatishousedinagrooveinthecollarandrubsagainsttheinsideboreof
thethimble.Ifthecollarisseparatedtoofar,thegrooveandthespringareexposed.Thespring
canfalloutandifnotlost,itisawkwardtorecompressthespringsothatthethimblewillslide
completelybackontothecollar.
Oncethematingsurfacesareclean,matethekeyandthekeywayandfitthecollar/thimbleassemblyto
theshaft.Refitthewasher andthesecuringnut, andtighten.Tightenuntilthehandwheel,thimble and
collar assemble are too tight to move. Undo the securing nut a quarter turn and check that the drive
handlerotatesfreelyandthereisnotexcessivebackwardandforwardplayintheshaft(Thehandleetc,
formsonesideofthedrivescrewanchorintotheslide).
ChesterUKCobraLathe
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Maintenance
TheLatheisaprecisiontool.Inordertomaintainthisprecisionand prolongitsusefullife,itis
advisedthatyoufollowtherecommendeddailyandperiodicmaintenancetablesprintedbelow.
Daily
Carry out a visual inspection. Repair any damage immediately. Minor damage to the beds should be
takenoutwithanoilstone.
Movethesaddleandthetraverseslidebackandforthbyhand;checkthatthemovementissmooth.
Spreadalightfilmofoiloverthebedandthetraverseslidebed.
Directlysprayoilontheleadscrewaftereveryuse.
Ifthelatheissubjecttoprolongeduse,oiltheleadscrewandbearingsevery34hours(Theleadscrew
islocatedunderneathandrunstheentirelengthofthelathebed).
DailyAfterUse
1. Cleanallswarfandchipsawayfromthemachinebed,slidesurfaces,andthetoolpost.
2. Exercisetheslidesandensurenoswarfetc.,islodgedinthedriveshafttunnels.Ifyouhave
beenusingacoolantmakesurethemachineisthoroughlydriedoff.
3. Checkthetool,ensureitisusableforthenexttime,ifnotresharpenorreplacethetooltip.
4. Lightlysprayoiloverallthemachinesbedsandsurfaces,andthetailstockbarrel.
5. Cleanandlightlyoilanytoolsyoumayhavebeenusing(centres,drillchucks,spanners,chuck
keysetc)andputthemaway.
6. SwitchOFFthepowersupply.Disconnecttheplug.
7. Coverthemachineoverwithadustcloth.
Weekly
1. Movethetraverseslidefullybacktogiveaccesstothetunnel,blowouttomakesureallswarf
is clearedawayandheavilysprayoil in thetunnel, exercisethe slideto workthe oilintothe
drivethreadandtolubricatethedog.
2. Sprayoiltheslideandthelathebed,exercisethesaddleandtheslidetospreadtheoiltoall
surfaces,bothhiddenandvisible.
3. Sprayoilunderthebedontotheleadscrew.
4. Check the movement of the saddle and the traverse slide, check it is smooth and ‘tight’, if
necessaryresetthegibstrips.
Monthly
Checkthebelttension.Ifnecessaryresetthebelttensionbylooseningthetwomotorsecuringcaphead
bolts,retensionthebeltandresecurethebolts.
Every6Months
Because the D.C. motor has a heavy permanent magnetic field, it is advisable to dismount the lathe
every6months,removethesplashguardandremovealltheswarfthatmayhavefounditswayintothe
motorhousing.
ChesterUKCobraLathe
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OilingPoints
ChesterUKCobraLathe
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ChangeGearTable
ChesterUKCobraLathe
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