958.4ManipulatingandjoiningCorrugatedcardboardPVAglue is ideal for joiningthicker cardandcorrugatedcard. Dryingtimescanbebetweenafewminutes andtwotothreehours, but onlyathinlayer isrequiredforastrong, long-lastingbond. Superglueandhot glueguns canalsobeusedtojoinboardsandcorrugatedcardwhena fast-settingbondis required. FoamboardandStyrofoamPVAglue is alsoideal for joiningfoamboardandStyrofoam. Maskingtapeordressmakerspins canbe usedtoholdthematerials together whilethegluedries. Hotgluegunsandsolvent-basedadhesives suchas cyanoacrylate(Superglue) mustnotbeusedonfoamboardandStyrofoamas thesolvent will melt thefoam. PVCfoamandCorrifluteContact adhesivesuchas gluestickandsolvent-basedadhesivessuchasSuperglueandpolystyrenecement arethebest methodsof joiningCorrifluteandPVCfoam. Epoxyresinscanalsobe used, providingthesurfaces areroughenedupwithabrasivetogivethegluea'key'. Epoxy resins must bemixedandappliedinawell ventilatedareaandthewearingofprotective gloves is advised. For more informationonjoininglaminatedboardsusingadhesive, pleaserefertoSection8.7. Table 8.6 Commonadhesives andtheir propertiesAdhesive Material PropertiesGlue sticks Paper andthincard•Easytoapply, inexpensiveandmess-free•Canunstickover time, piecescanbreakoff,makingsurfacelumpy•Quick-settingSpray glues Paper andthincard•Givealight evencoating•Canbepermanent or temporary•Quick-setting•CanbemessyPVAglue Thicker card, corrugatedcardboard, foamboard, Styrofoam•Driesclear •Inexpensive•CanbewatereddownHot glue guns Thick card, Corriflute•Quick-setting•Canburnmaterial anduser•Cool melt versionsavailable•ColouredgluesticksavailableCyanoacrylate glue (Superglue) Corriflute, PVCfoam•Quick-setting•Verystrongbond•Short shelf life(approx. oneyear)Polystyrene cement Corriflute, PVCfoam•Driesquickly•Clear finishContact adhesive Corriflute, PVCfoam•Must beappliedtobothsurfaces•Needstopartlyset beforejoining•Instant bond•Doesnot requireclampingEpoxy resin Corriflute, PVCfoam•Needstobemixedwithhardener•Verystrongbond•Givesoff strongfumes
96Chapter 8Papers andboards 8.5StructuralintegrityLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜howandwhypapersandboardscanbereinforcedtowithstandexternalforcesandstresses➜theprocessesthatcanbeusedtoensurethestructuralintegrityofaproduct.Thestructural integrityof aproductorobjectisitsabilitytoholdtogetherunderaload,includingitsownweight, withoutbendingorbreaking. Ifanobjecthasstructuralintegrityitwill performitsfunctionwithoutfailingforaslongasitwasdesignedtodoso.If theobject doesnot holdtogetherbecauseithasbeenstressedmorethanitcanwithstand, thisisknownasstructural failure. Thiscouldrefertojustapartoftheobject'sstructureor thewholething. As athinsheet, material papercanappeartohavelittlestructuralintegrity.Thestructuralintegrityof paper canbegreatlyincreasedinvariousways, however.FoldingFoldingasheet of paper or thincardturnsitfromaflatsheetthatwillbendandflexeasilyintoastructure. Thefoldcreatesarigidsectionwithinthepaperthatcansupportitsownweight andadditional weight. Figure 8.12 Aflat andafoldedsheet of paper Figure8.13PaperfoldedmultipletimesByfoldingthepaper anumberof timesthestructuralintegritycanbefurtherincreased.
978.5StructuralintegrityCurvingandbendingAs well as folding, paper andcardcanbebent intocurvedshapes suchas a cylinder, ashapethat hasinherent strengthandstructural stability. The wavy centresectionof corrugatedcardiswhat givesit its rigidity andstrength. Astandardcardboardboxwithfour vertical-foldedcorners will beabletowithstandandholdtheweight of anaverage-sizedhuman. Thestructural integrity providedbytheboxshapemeansthat many boxes canbestackedontopof oneanother without collapsing. Thetriangulatedshapesinthecentreof Corriflute work inthesameway. The structural integrity of cardboardcanalsobeincreasedby shapingit intoa structure. Cardboardeggboxesareanexcellent exampleof this. Whenthecardismanufactured, the pulpis sprayedontoadimpledmouldinsteadof aflat meshsheet, similar tothepapier mâchéprocess. Theshape of thecartonnot onlysupports eachindividual eggandisolates it fromtheother eggs, but thestructurecreatedalsohelps toabsorbshockandprotect theeggs against breakage. This typeof structureiscalledamonocoque, meaning'singlestructural skin'. Monocoquestructures arecommonlyusedinboat hull design, andmonocoquechassis areusedonmanymodernvehicles. Structural integrity canalsobeincreasedbyreinforcingone material withanother. Foamboardis madeupof athinlayer of foamsandwichedbetweentwolayersof paper or thincard. Ontheir own, thesheetsof paper andfoamwouldhavevery littlestructural integrityor strength. If stoodontheir edgetheywouldcollapseor fall over. Byjoiningthe materials together, however, theygainstructural integrity. Thefoamboardinsideallowstheouter paper layers tostandontheir edgeandnot bendaseasily. The paper outer layers spreadanyloadacrossthefoaminsteadof it beingconcentratedinoneplace. ACTIVITYCollectaroundtentoiletrollorkitchenrolltubes.Placethetubesverticallyonthefloortogether,withthetubesfacingupwards,andplaceasheetofMDForplywoodontopofthem.Gentlystandonthestructure,anditshouldtakeyourweight. Removetwoofthecentraltoilet/kitchenrolls,andrepeattheexercise.Progressivelyremovemoretubesandrepeatthetestsuntil thestructurecollapses.ACTIVITYCutdownatoiletroll sothatitisthesamelengthasitsdiameter. Trytosquashthetubeonewaythentheother.Figure 8.14 Cardboardboxes canbestackedduetotheir vertical-foldedcorners Figure8.15Acardboardeggbox
98Chapter 8Papers andboards 8.6MakingiterativemodelsLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜theprocessesandtechniquesusedtoproduceearlymodelstosupportiterativedesign. ProcessesandtechniquesPaper andboardscanbeusedinavarietyofusefulandinterestingwaystohelpyouexploreyour earlydesignideasandtosupportiterativedesigninginschool.Paperandthincardareextremelyversatilematerialsformodel-makingastheycanbeeasilyfolded,cut,bent,printedonandstucktogether.PapermodellingoriginatesinJapan-origamiistheartofpapermodellingwithouttheuseofglue. Everydayfoldedobjectssuchaspaperaeroplanesandpaperhats, whichwehaveallmadeorseen,areexamplesofsimpleorigami.Paperandcardmodellingcanuseprintedpartsorpatterns, whichcanbecutoutandassembledbyslottingorgluing. Paperandcardcanbemodelledintoallmannerof formsandarefrequentlyusedformodellingvehiclessuchascars, lorries, boatsandspacecraft,aswellasanimals, furniture, buildingsandbridges.Theinternetprovidesexamplesofmanydownloadablemodelswithrealistictextures, fromsimpleshapesuptocomplexlife-sizemodelswithextremelyfinedetailsandthousandsofpiecestoassemble. Themost commonmethodsof assemblinga3Dshapeusingpaperorcardinvolvestheuseof nets. Netscanbedrawnorprintedontopaperorcardandthenscored,folded,cutoutandjoinedtoformtheshaperequired. STRETCHANDCHALLENGEDrawanet anduseit toconstructthefollowingshapes:lAcube505050mmlAcuboid604030mmlAnequilateral triangularprism(trianglesides5060mmhigh)lAsquare-basedpyramid606060mmFigure 8.16 Apaper aeroplane
998.6MakingiterativemodelsPaper andcardmodelsPaper andcardareextremelyuseful for makingtemplatesor patterns for items that will bemadefromsheet metal, polymeror textiles. By first makingatemplateinpaper or card, designerscaneasily trimandshapethepatterntoexactlytheright sizeandfoldor bendit totherequiredshape. If thetemplateisnot correctandrequires modificationor completelyredoing, it ismucheasierandcheaper todothis incardthaninmetal or polymer. Onceitis correct it canbelaidout ontothesheet material anddrawnaroundsothat the'real' itemcanbemadetotheexact size. ModelsfromothermaterialsFoamboardis anextremelypopular material for makingarchitectural models. Thethickness of thematerial meansitcanbestoodupandjoinedtoformwalls, floors androofs. Windows, doorsandother aperturesareeasytocutoutandthe surface canbescored, indented, printedor drawnontoinordertoachieverealisticarchitectural effects. Figure 8.18 An architectural model madeusingfoamboardStyrofoamis anexcellent modellingmaterial duetoitsability tobeshapedandsandedeasily. It canalsobeusedtoformlightweight buildingblocks, whichcanbejoinedtogether toformlarger models. Styrofoamisoftenusedinthe modellingprocess as amouldfor vacuumformingor GRP. For more informationontheuseof Styrofoam, vacuumformingandpolymer laminatedlayers (CorrifluteandPVCfoam) for modelling, seeSection8.6. Figure8.17AcardtemplatelaidoutonsheetmetalFigure8.19AStyrofoammould
100Chapter 8Papers andboards 8.7FinishesLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜thedifferentfinishesthatcanbeappliedtopaper,boardandlaminatedlayers➜theprocessesusedforfinishingpaper,boardsandlaminatedlayersforspecificpurposes. PaperThepropertiesandaestheticsof paperandboardcanbealteredandimprovedbyapplyingdifferent surfacetreatments. Arangeofdifferentcoatingscanbeappliedtoimprovetheopacity, lightness, surfacesmoothness, lustreandcolour-absorptionofpaper.Sometypesof coatingaredoneduringthemakingprocesswhilethepaperisinthepaper-makingmachine. Other typesareappliedseparatelyafterthepaperhasbeenproduced.Cast coatingsareappliedafterthepaperhasbeenproduced.Oneorbothsidesofthepaperarecoatedwithchinaclay, chalk, starch, latexorotherchemicals.Thewetcoatedpaperis thenpressedor rolledagainstapolishedhotmetaldrum, creatingafinishsosmooth,reflectiveandshinythat itcanseemalmostmirror-like. Cast-coatedpaperalsoholdsinkwellandproducessharp, brightimageswhenprintedon. SupercalenderingSupercalenderinggivespaperanevensmoothersurface. Thepaperpassesthroughacalenderor supercalender, whichisaseriesof rollerswithalternatelyhardandsoftsurfaces.Thepressureonthepaper createsasmoothandthinpaperwithaveryhighlustresurface.Supercalenderedpaper is primarilyusedfor glossymagazinesandhigh-qualitycolourprinting.TypesofpaperfinishTable8.7CharacteristicsandusesofdifferentpaperfinishesPaper finishtypeCharacteristicsUsesCast-coatedpaper Providesthehighest glosssurfaceofall coatedpapersandboardsLabels,covers,cartonsandcardsLightweight coatedAthin, coatedpaper, whichcanbeaslightas40gsmMagazines,brochuresandcataloguesSilkor silkmatt- finishedpaper Smooth, matt surface; highreadabilityandhighimagequalityProductbookletsandbrochuresCalenderedor glossypaper Glazedshinysurface; canbecoatedand/oruncoatedColourprintingMachine-finishedpaper Smoothonbothsides; noadditional coatingsappliedafter leavingthepaper-makingmachineBookletsandbrochuresMachinecoatedCoatingappliedwhileitisstill onthepapermachineAlltypesofcolouredprintMatt-finishedpaper Slightlyroughsurfacepreventslightfrombeingreflected; canbeeithercoatedoruncoatedArtprintsandotherhighqualityprintwork
1018.7FinishesCardandboardfinishesVarnishVarnishcoatings areathincoatingof matt, silkor glossvarnishthatcanbeappliedtopaperor cardproducts toenhancetheir lookandfeel. Thecoatingalsoaddsadditional protectionandmakes thepaper or cardlast longer. Varnishedcardhasahighshinefinishandfeelslikeplastic tothetouch. Spot UVvarnishis a special varnishthat is appliedtotheprintingsurface, thencuredorhardenedby ultraviolet (UV) light duringtheprintingprocess. Spotvarnishisonlyusedoncertainareas of thepaper or card. Thevarnishmakesthecoatedareashinierandclearerthanthe surroundinguncoatedareas, makingpartsstandout. Hot foil applicationHot foil applicationor foil blockingis usedtoproducemetallicfinishessuchas goldor silver oncardandpaper products. Multi-colouredandholographic foils arealsoavailable. It isoftenusedfor letteringoninvitations andbusiness cards. The hot foilingprocess uses amagnesiumor copper dieshapedtotherequiredfoil designthat is heatedup. Thefoil isfedbetweenthecardandthe die, whichis thenpressedagainst thecard, releasingthefoil ontothe cardwherethedietouches. Hot foil applicationiscurrentlytheonly methodof achievingametallicglossyfinish. EmbossinganddebossingEmbossinganddebossingactuallygivepaper andcardathree-dimensional imagethat canbeseenandfelt. Embossingcreatesaraisedarea onthepaper or cardthat standsout slightly. Debossinghasthe oppositeeffect andcreates asunkenor loweredarea. Usingbothtechniques cancreatestunningvisual effects. The embossinganddebossingprocess usestwometal formers(amaleandafemale)intheshape of thedesignrequired. Thesefit together perfectly. Thecardisplacedbetweenthetwoformers andheat andpressureareapplied. Thissqueezesanddeformsthefibresofthematerial intotheshapeof theformers. Theembossingprocess1Cardis placedbetweenthemaleandfemaledies. 2Heat andpressureareapplied. Cardretains shapewhenremovedfromthedies. Figure8.20Aninvitationwithfoillettering1. CardisplacedbetweenthemaleandfemalediesFemaledieMaledieSheetofcardorpaper3. Cardretainsshapewhenremovedfromthedies2. HeatandpressureareappliedFigure 8.21 Abusiness cardwithembossinganddebossing
102Chapter 8Papers andboards LaminatingThecoatingprocessesappliedtopaperdescribedatthestartofthissectionaresometimescalledlaminates, but theyusespray-onmethodsthataredoneduringorstraightafterthepaper-makingprocess. Theother formof laminating, describedbelow, isusuallydonetofinisheddocumentssuchas menus, posters, signs, identitybadgesandotherprinteddocuments.Itisdoneinorderto:limprovetheir strengthandresistancetobending, creasingorrippinglwaterproof thedocument, allowingittobewipedcleanandpreventingitsmudgingorgoingsoggylimprovetheappearancebymakingthedocumentshinylincreasethelifespanof theprinteddocument. Laminatinginvolvesapplyingafilmofclearplasticbetween1.2and1.8mmthicktooneorbothsidesof paper or thincard. Therearethreemethodsoflaminatingadocument:lPouchlaminationlThermal or hot laminationlColdlamination. PouchlaminationPouchlaminationusesthinclearplasticpouchesthatareavailabletofitstandardpapersizessuchasA3andA4.Thepouchesarecoatedontheinsidewithathinlayerof heat-activatedglue. Thedocumentisplacedinsidethefilmpouch, whichisslightlylargerthanthepaper,beforebeingfedthroughalaminatingmachine.Insidethemachinethepouchisheatedandpressedbetweenrollers. Theheatactivatestheglue,whichsealsthepouchtogetherasitispressedthroughtherollers,encasingthedocumentinsideit. Pouchlaminatorscandoonlyonedocumentatatimesoareideal forsmallvolumeitems.Laminatingpouchesandlaminatingmachinesarereasonablycheaptopurchaseandreadilyavailableinschools.Thermal orhotlaminationWherelargevolumesof laminateddocumentsarerequired, commerciallaminationmethodsarerequired. Thermal laminationusesrollsofthinheat-sensitivepolymerfilm.Therearedifferent typesof filmavailablewithdifferentproperties: lPolypropylenefilmhasgoodresistancetowater, chemicalsandcracking,excellenttransparency, andcanberecycled. Commonlyusedforwriteon/wipeoffproductssuchas calendars, labels, etc. lPET(polyester) filmhasall thebenefitsofpolypropylenefilmwithimprovedgloss,scratch-resistanceanddurability. Itiscommonlyusedforbookcoversanddocumentsthat haveundergonefoil application. lNylonfilmisconsiderablymoreexpensivethanotherfilmduetothehightemperaturesneededfor it tolaminate, butithasahighchemical-, mechanical-andabrasion-resistance. It will alsoabsorbmoistureinasimilarwaytothepaper,whichpreventsthedocumentscurling, andiscommonlyusedforsoftcoverssuchasonpaperbackbooks.As well asclear laminatingfilms, metalliccolourssuchasgoldandsilverareavailable.Holographicfilmsandiridescentfilmsthatshiftandchangecolourastheycatchthelightcanbeusedtogiveinterestingeffectstotheprinteddocumentsbeinglaminated.Figure 8.22 Alaminatingmachine andlaminateddocument
1038.8UsingdigitaldesigntoolsColdlaminatingColdlaminatingis donewhenonlyonesideof thepaper or cardistobecoated. Coldlaminatingdoes not useheat, andmanycoldlaminationmachinesareinexpensivehand-operatedmachines that donot requireanypower. Thelackof heatmakesthemidealfordocuments that might bedamagedbyheat, suchasphotographs. Coldlaminationuses filmthat has athincoatingof pressure-sensitiveadhesiveappliedtoone side. Thefilmis placedover thedocument andpassedthroughthemachine'srollers, whichpress downandsmoothout theadhesive. Thissticksthefilmfirmlytothedocument. It canthenbetrimmedtosizeif necessary. Coldlaminationis mainlyusedinthesign-makingindustry. Byadjustingthepressureappliedby the rollers, coldlaminationcanbeusedonother graphicproductssuchasfoamboardandPVCfoam. It is alsousedinother areasof industry, suchascoatingsheetsofglassorasaprotective coatingfor stainless steel, aluminiumandacrylic. Other laminatedlayers suchas CorrifluteandPVCfoam, whicharepolymers, canhaveadditional surfacefinishes appliedtothem. For moreinformation, seeChapter11, Polymers. 8.8UsingdigitaldesigntoolsLEARNINGOUTCOMESBy theendof this sectionyoushouldknowaboutandunderstand:➜theuseof 2Dand3Ddigital technologyandtoolstopresent,model,designandmanufacturesolutions inpaper andboard. Useof2Dand3Ddigital technologyandtoolsDigital technologies: CADandCAMComputer-aideddesign(CAD) is adigital designtool that usescomputertechnologytoproduce designs insteadof, or inadditionto, drawingbyhand. CADallowsthedesignertoproduce detailedworkingdrawings of designstoanaccuracyof athousandthofamillimetre. DraftingonCADcanbedoneintwodimensions, for exampleonpaper, orinthreedimensions. CADalsoenables thedesigner toexploredesignideasandvisualiseconceptsthroughfullyrendered3Dimages, whichcanberotatedandviewedfromanyangle. ManyCADprogramscanalsosimulatehowadesignwill behaveinuseandperforminthereal world. There are many different types of CADprogramavailable, fromsimpleprogramsthatcanbe downloadedor usedonlinefreeof chargethroughtoindustry-standardpackages. Many schools haveCADpackages that aresimpletouseandcancreatedetailedworkingdrawings of final products inisometricandorthographicprojections. WhiledifferentCADpackages will vary inthewaytheywork, themajoritywill havesimilartoolsandcommands, andwill usually havebuilt-intutorials toteachyouhowtousethem. Animportant advantageof CADis that it allowsdrawingsof productstobecreatedandturnedintoreal products throughtheuseof computer-aidedmanufacture(CAM). Awiderange of CAMmachines is availablethat cancreateproductsfrompaperandboards. Someof these are 2Dmachines that cancut, scoreandengraveondifferentsheetmaterials, andothers canmill andform3Dshapes out of Styrofoam. KEYTERMSCAD:Computer-aideddesign.CAM:Computer-aidedmanufacture.
104Chapter 8Papers andboards OnceadrawingofadesignhasbeencreatedonCAD, itcanbeoutputinvariousways.Themostcommonmethodofoutputtingadesignisbyprintingitontopaper.Thereisavastarrayofprintersavailableandmosthouseholdswithacomputeralsohaveaprinter.SmallerprintersthatcanprintsizesuptoA4arerelativelyinexpensive. LargerprintersuptoandoverA0insizeareusedinindustryforengineeringdrawings, houseplansandmaps.Figure 8.23 Anorthographic inTechsoft Vinyl cuttersAfter printers, thesimplestCAMmachinesthatmanyschoolshaveavailablearevinylcutters.Theseare2DmachinesthatcantransferlinedrawingsonCADontoself-adhesivevinyl.Vinylcutters haverollersthat movethevinyl sheetbackwardsandforwardsononeaxisandabladethat moveshorizontallybackandforthontheoppositeaxis.Thebladecutsthroughthetopsurfaceof thevinyl butleavesthebackingsheetintactsothatthefinisheddesigncanbepeeledoff andappliedtoasign, windoworvehicle, forexample.Vinyl cuttersareavailableinavarietyofdifferentsizes, fromsmallA4sizeuptocommercialsizes of over A0. Figure8.24Avinyl cut logo
1058.8UsingdigitaldesigntoolsLaser cutters areusually usedfor cuttingsheet materials, but theycanalsocut awide range of other materials. Most schoolshave laser cutters that cancut materials suchas paper, cardboard, foamboard, PVCfoam, polystyrenesheet andacrylic. Moreexpensive machines areavailablethat cancut plywood, MDF, hardwoodandthinsheet metals. Laser cutters havea flat 'bed' that thesheet material is laidonto. Thelaser thenmovesacross the sheet alongthex- andy-axes, cuttingall theway throughor part wayintothe material. Thespeedof thelaser anddistance fromthebedcanbealteredandset tosuit thespecific material beingcut. Laser cutters areavailablewithbedsizes fromapproximatelyA3uptoindustrial machineswithbeds 3metres inlength. Different machinescut theworkindifferentways-bymelting, burning, vaporisingor blowingawaymaterial withajet of gas, dependingonthematerialbeingcut. Laser cutters aremuchquicker andmoreaccuratethancuttingbyhandandcancut out intricatedesigns that wouldbeextremelydifficult or impossibletodobyhand. MillingmachinesComputer numeric controlled(CNC) millingmachinesusearotatingcuttertoremovematerial fromthesurfaceof aworkpiece. Millingmachinesaremainlyusedfortheshapingofblocks of aluminiumandother metals, but canalsobeusedinexactlythesamewayforshapingandmillingdesigns inStyrofoam. For moreinformationonmillingmachines, seeSection8.7. Figure 8.26 ACNCmillingmachinemillingsomeStyrofoamKEYTERMSCNC:Computernumericcontrol.Figure8.25Alasercutterandalaser-cutitemKEYPOINTAprinterisadigitaldesigntoolthatcanbeusedwithpaperandboardwhendesigningproducts.
106Chapter 8Papers andboards 8.9ManufacturingmethodsandscalesofproductionLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜themethodsusedformanufacturingatdifferentscalesofproduction➜manufacturingprocessesusedforlargerscalesofproduction➜methodsof ensuringaccuracyandefficiencywhenmanufacturingatlargerscales.ScalesofproductionPaper andboardproductscanbemadeusingdifferentmethodsdependingonthequantitiesrequired. One-offproductionOne-off productionisthemakingof asingleproduct(knownasa'one-off').Ahandmadebirthdaycardisanexampleof aone-offproduct. One-offproductsarelabourintensiveandtimeconsumingtoproduce. Someone-offproductsareentirelyhandmade,whereasothers useautomatedprocesses. One-offproductsareoftenproducedforaspecificclient'srequirementsor needs. Oftendesignerscreateaone-offprototypeoftheirdesigntoshowwhat it will looklikeor howitwill function. BatchproductionBatchproductionisasystemof productioninwhichalimitednumberofitemsisproducedinonego. Batchproductionenablestheproductionofsimilaritemswithslightvariations,suchas changestotext or colour. Digital printingFor paper andcardproducts, digital printingisthemostcost-effectivebatchproductionmethodasit allowsvariationstobemadeeasily, suchasenlargementandreduction,cropping, rotating, andsoon. Digital printingisidealforpersonaliseditemssuchaspartyinvitationsor companynamebadges, asthemaindesignstaysthesamebutthedetailscanbechangedfor eachcopyprinted. Digital printersareinexpensivetobuy,readilyavailableandmanypeoplehavethemforhouseholduse.Thecostpersheetofusingadigitalprinterishighcomparedtoothertypesof commercial printing, butbecausetherearenosetupcostsandonlyalimitednumberofprint-outsareneeded,theyarethebestoptionforsmallprintruns.Figure8.27Adigital printer
1078.9ManufacturingmethodsandscalesofproductionScreenprintingScreenprintingis another methodof printingthat issuitablefor batchproduction. Screenprintingis usedtocreaterepeatingpatterns or designs, suchas onwallpaper or fabrics. Screenprintinguses aporous fabricmeshscreenstretchedover a woodenframe. Thescreenis theexact sizeof thepatternor designrequired. Thelightest colour isprintedfirst, by maskingoff theparts of thescreenthat arenot inthat colour onthedesign. This creates astencil of thecolouredparts tobeprinted. Theframeisthenlaidontothe paper or fabric, asmall quantityof inkisaddedandasqueegee is usedtospreadtheinkevenlyover thewholeof the screen. Theink is pushedthroughthemeshbythesqueegee intheunmaskedareas andontothepaper or fabric below. Thescreenis thenmovedtothenext positionandthe process is repeated. Once the lightest colour has beenprintedacrossthewholearea required, thescreenis washedandmaskedupfor thenext colour. Theprocess is repeateduntil all thecolourshave beenprinted. WoodenframeMeshscreenThedesigntobeprintedFigure8.28Thescreenismadetothesamesizeasthedesign.1 Screen masked off for 2Yellowpart printedyellowink 3Screenmaskedofffor4Redpartprintedredink5 Screen masked off for 6Bluepart printedblue ink 8Greenpartprintedtocompletedesign7ScreenmaskedoffforgreeninkFigure 8.29 The screenprintingprocess
1098.9ManufacturingmethodsandscalesofproductionOffset lithographyWhenlarge numbers of graphicproductsarerequired, commercial printingmethods arethebest option. Offset lithography is oneof themost commonformsof commercial printingusedtoday. Theprocess uses four inkcolours: cyan, magenta, yellowandblack (calledthe'key'). Thesecoloursare oftenabbreviatedas CMYK. Just thesefour colourscanbeoverlaidtocreateothers, for exampleprintingcyanontopof yellowcreates green. The initial settingof theprint runis themost expensivepartof the process, as it requires animagesetter toproducefilmsfor eachof the four colours of theartwork. Thesearethenusedtoproduce a set of printingplates. The principal of offset lithographyis that oil andwater donotmix(oil will separatefromwater). The imageontheplateis set toattract theinkbut repel water, whereasthenon-image parts of theplateattract moistureandrepel theink. Theplateiskeptwetduringtheprintingprocess sothat theinkwill stickonlytotheareasrequired. DiecuttingDie cuttingis usedwhenyouwishtocut manyidenticallyshapedproducts, suchasinmassproduction. Theprocess works inaverysimilar waytoapastrycutter: asharp, shapedblade(thedie) is loweredontothematerial tobecut andapressisappliedtoforcethroughthematerial. Asimilar methodis alsousedtocreasepaper andcardproducts, onlyabluntorroundedblade rather thana sharpbladeis used. Thematerial isnot cutall thewaythrough, butacrease is left. This is usedwhencreatingproductsthat needtobefoldedsuchasboxesandsurface developments. FlexographyFlexography is another commontypeof mass-productionprintingprocess. Flexographyuses water-basedinks rather thanoil-based, whichallowsawiderrangeofinkstobeused. The water-basedinks drymuchfaster sotheprocessismuchquicker, andalthoughtheprint quality is not as good, thecosts aresignificantlylower. Itislargelyusedforprintingonpackagingsuchas corrugatedcardboardboxes, cartons, sweetwrappersandplasticcarrierbags, wherethequality of theprint is less important. As inoffset lithography, thefour colours - CMYK- areprintedoneatatime. Aflexibleprintingplateis mountedontotheplatecylinder, andthematerial tobeprintedispressedagainst it by theimpressioncylinder. Inkistransferredtotheprintingplatefromaninkpanvia tworollers (a fountainroller andananiloxroller). TobecutandfoldedOil-basedinkInkingrollersDampeningrollersWaterGuiderollersWebofpaperRubberrollersReelPrintingplaterollersFigure8.32OffsetlithographyprintingACTIVITYUseamagnifyingglasstolookcloselyatthequalityofprintingonsomedifferentproducts.Comparetheprintqualityoftheillustrationsandtextinthisbooktotheprintingonitemssuchascorrugatedcardboard,drinkcartons,andsoon.STRETCHANDCHALLENGETakeasheetofA4paperandaflatobjectsuchasacoin,badgeorkey.TrytotessellatetheobjectbyfittingasmanyaspossibleontotheA4paperbydrawingaroundthem.Platecylinder Fountainroll ImpressioncylinderAnilox roll InkpanFigure8.33Flexographyprinting
110Chapter 8Papers andboards 8.10CostandavailabilityLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜howthecostandavailabilityofspecificpapersandboardscanaffectdecisionswhendesigning. ➜howtocalculatethequantities,castandsizesofmaterialsrequiredinadesignor product. CostandavailabilityconsiderationslPaperandcardboardareamongthemostinexpensiveandwidelyavailablematerials.Normal A4whitepaper thatweuseeverydayforsketching,printingandwritingoncostsaround1pper sheet, whilelargersizessuchasA1andA0costaround10ppersheet.lCardboardandglossypapertypesaremoreexpensivebutarestillwidelyavailableinhighstreet stationeryshops, andtheyareinexpensivecomparedtoothermaterialssuchas woods, metalsandplastics. lFoamboardiswidelyavailableinsizesfromA4toA1. Itiskeptinstockbyartandhobbyshops. Pricesrangefromapproximately50pforanA4sheetuptoaround£2.50forA1.Thethicker thesheetsare, themoreexpensivetheybecome.lPVCfoamisalsowidelyavailablefromspecialistsuppliersbutcanalsobeboughtontheinternet under varioustradenames. Small sheets(A4size)costaround£2persheet,andthis rangesuptolarge(24001200mm)sheetsthatcancostaround£50.lStyrofoamisusedinmanyindustriesasaninsulationmaterialandisavailablefrommanyDIYstoresandontheinternet. Astandard-sizedsheetof25mm-thickStyrofoam(2400600mm) costsaround£7. As withmost other materials, thecostreducesthemoreyoupurchase.Thereforewhendesigningaproduct andplanningthemanufactureofamodelorprototype,itisessentialthat youcarefullyconsider andcalculatetheamountofthematerialyouwillneed.If,forexample, youneedjust over threeA1sheetsoffoamboard, itmaybecheapertobuysevensheets of A2thanfour sheetsof A1. Another considerationtotakeintoaccountisthatthecostpermm2ofallsheetmaterialswillgenerallydecreaseasthesheetsizeincreases. Inmanycasesitmaybemoreeconomicaltobuyalargesizesheet andcutitintosmallersheetsyourself.
1118.10CostandavailabilityExampleAdesigner needs sevenpieces of A4-sizefoamboardtomakeaprototypeproduct. lOne A4sheet of 25mmfoamboardcosts£0.45. Sevensheets@£0.45=£3.15total. lApack of tenA4sheets costs £3.00. lAsheet of A1-sizefoamboardcosts £2.75. The cheapest way toget thefoamboardisfor thedesigner tobuyanA1sheetfor£2.75andcut this intoeight A4-sizepieces. Hewill havesevenpiecesandonespare. KEYPOINTSlPaperandboardsarewidelyavailableandoneofthemostinexpensivematerials.lThecostpermm2decreasesasthesheetsizeincreases.
112Chapter 9Timber CHAPTER9TimberYoulearnt about thedifferenttypesoftimberinChapter5. Thischapterincludesmorein-depthknowledgeontimber. 9.1PhysicalandworkingpropertiesLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstandthephysicalandworkingpropertiesofarangeofdifferenttimbersandmanufacturedboards,including: ➜howeasydifferenttypesoftimberaretoworkwith➜howwell theyfulfil therequiredfunctionsofproductsindifferentcontexts.For centuries, our ancestorsusedwoodtoputaroofovertheirheads,wallsundertheroofandfurnitureinsidethewalls. Itisnature'sstrongest, mostreadilyavailable,renewable,warmandwelcomingbuildingmaterial. Timberisthetermgiventowoodthathasbeenconvertedintouseableformssuchasboards, planks, sections.Itisanorganic,sustainable,natural andrenewablematerial. Itisstrong, lightweight, adaptableandcompetitivewithother materialsintermsof cost. Itactuallycontributestoreducingclimatechange,becauseit requireslessenergytomanufacturethananyotherbuildingmaterial.Youhavealreadylearnt inChapter5timbercanbeclassifiedintothree'families':lSoftwoods(fromconiferoustrees)lHardwoods(fromdeciduoustrees)lManufacturedboards(manufacturedsheetsoftimberusingbothsoftandhardwoods).Thefollowingtablesoutlinethephysical andworkingpropertiesofarangeofcommonsoftwoods, hardwoodsandmanufacturedboards, alongwithsomeexamplesoftheirtypical uses. CommonsoftwoodsTable 9.1 Physical andworkingpropertiesof commonsoftwoodsName Physical andworkingpropertiesTypicalusesRedwood(Scots pine) Straight grain, knotty, easy towork, finisheswells, durable; widely available andrelatively cheap. Suitableforall insidework.Woodturning.Most-usedsoftwoodinUK.Western redcedar Resists insect attack, weather anddryrot duetonatural preservative oils. Lightweight, soft, knot-free, straight- grained, very durable. Attractivesurface. Outsidejoinery.Buildingcladding.Bathroomandkitchenfurniture.Panellingwalls.Parana pine Hard, straight grain; usually knot-free; fairlystrong, workseasily; fairly durable. Internal buildingworksuchasstaircasesandbuilt-infurniture.Whitewood(spruce) Easy to work, fairly strong, resistant tosplitting. Cancontainpockets of resin. General constructionwork.Crates.KEYTERMSClimatechange: Achange inglobal climate apparent fromthe mid- tolatetwentiethcentury onwards. Organic: Derivedfromlivingmatter. Renewable: Anatural resource that is not depletedby use. KEYPOINTWhendesigning, it is important toknowandconsider the physical andworkingproperties of different timbers tomake sure youselect the best material.
1139.1PhysicalandworkingpropertiesCommonhardwoodsTable 9.2 Physical andworkingproperties of commonhardwoodsName Physical andworkingpropertiesTypicalusesBeech Very tough, hard, straight andclose-grained. Withstandswear andshocks, polishes well, liabletowarp. Most-usedhardwoodinUK.Toys,furniture,woodentools.Goodforsteambending.Ash Wide-grained, tough, very flexible. Finishes well. Baseball bats,flooring,toolhandles.ElmTough, flexible, durable, water-resistant, liabletowarp. Canbedifficultto work due toits cross-grain. Gardenfurniture(iftreated),woodturning,furniture.Oak Heavy, hard, tough. Opengrain, finishes well, goodoutdoors. Duetocontaining tannic acidit will corrodesteel screws, leavingabluestain. Gardenfurniture,doors,floors,high-endfurniture.Mahogany Easy to work, wide boards available, polishes quitewell. Hasinterlockinggrain, which makes it difficult towork. Furniture,shopfittings,boat-building,doors,pool cues.Teak Hard, durable. Natural oils resist moisture, fire, acids, alkalis. Straightgrain, works well, very expensive. Laboratorybenches,ships'decks,high-endfurniture.Balsa Avery soft andlightweight woodwithacoarseandopengrain. Modellingstructuressuchasbuildingsandbridges.ModelboatsandairplanesCommonmanufacturedboardsTable 9.3 Physical andworkingproperties of commonmanufacturedboardsName Physical andworkingpropertiesTypicalusesPlywood Constructed of layers of veneer gluedat 90degreestoeachother whichmakes itvery strongandtough. Availablefor Structural, Exterior, InteriorandMarine work. Highstrengthtoweight ratio. Relativelystableunder changesin temperature andmoisture. Cuts relativelyeasilybut cansplinter. Usedforstrongstructuralpanellingboardusedinbuildingconstruction.Furnituremaking.Flexible plywood Designed to make curvedparts. Madeby gluingthreelayersof veneerwith the grain runningthesameway. Themiddleveneer isextrathin. Called “Flexi- ply”or “bendy plywood”Easier tocut thanregular plywood but canstill splinter easily. Curvedfurniture,bespokeshopfittings.Marine ply Moisture resistant formof plywood. Boatbuilding,decking.MDF Easily machinedandpaintedor stained. Smooth, evensurface. Availablein water and fire resistant forms. Usedmainlyforfurnitureandinteriorpanellingduetoitseasymachiningqualities.Oftenveneeredorpainted.Moisture resistant MDF Aversion of MDF that is resistant tomoisture. It isoftencolouredgreenUsedinareaswheremoistureisprone,suchasKitchensandbathroomsFlame retardant MDF Aversion of MDF that is resistant tofire. It is usuallycolouredpinkorblue UsedinthebuildingindustryforbuildingswherethereisanaboveaverageriskoffireBlockboardSimilar to plywoodbut thecentral layer is madefromstripsof timber. Good resistance towarpingandrelativelyeasytocut andfinish. Edgesare difficult to cleanupsosoftwoodedgingstripsareoftenused. Usedwhereheavierstrongerstructuresareneeded.Commonforshelvingandworktops.Chipboard Also known as Particle board. Madefromwoodchipsandshavingsglued/pressed together. Usually veneeredor coveredinplasticlaminate. Easy to cut but not particularly strong. Lightweight andweak. Cutseasilybut edges needcovering. Pronetoexpansionwhenexposedtomoisturewhere a moisture resistant versioncanbeneeded. Usedforkitchenworktops,usuallyveneeredorcoveredwithaplasticlaminated.Shelvingandgeneral DIYwork.STRETCHANDCHALLENGEChoose five commonproducts madefromtimber. Usetheinternettoidentifythetimbersusedtomake eachof these products. Thinkabout thefollowing: lWhat does the product do?lHowis theproduct used?lWhereisitused?
114Chapter 9Timber 9.2SourcesandoriginsLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜thesourcesandoriginsofarangeoftimbersandmanufacturedboards➜theprocessesusedtoconvertthemintoworkableforms➜theecological andethical issuesassociatedwiththeirconversion➜thedifferentwaysinwhichtimbercanberecycled.Whenatreehasbeencutdown, itsbranchesaretrimmedoffanditsbarkremovedbeforeitis cut roughlyintoboards, planksorveneer. Thisprocessisknownasconversion.Therearetwogeneral methodsof doingthis: plainsawingandquartersawing.Acombinationofthetwois oftenusedtoreducewaste. Plainsawingisthecheapestmethodbuttheouterplankstendtowarp.Quartersawingismoreexpensiveasit requiresmoretimeandlabourandproducesmorewaste.Quartersawnplanks aremorestable, however. Timber containsalot of moistureonceithasbeencut, whichmakesitverydifficulttoworkwith. For thisreasonit isusuallydriedoutbeforeuse, aprocesscalledseasoning.Theplanksof woodarestackedontopof eachotherinsuchawaythataircancirculatebetweenthemandreducetheamountof moistureinthem. Thisisusuallydoneoutdoorsunderroofingtoshieldthetimber fromsunshineandrain. Alternatively,thetimbercanbedriedfaster under controlledconditionsusingakiln. Naturalseasoningischeapandneedslittleskilledattention. It cantakeseveral years, however, dependingonhowthickthesectionis. Kilnseasoningtakesonlyafewdaysorweeksandalsokillsanyinsecteggsinthewood(woodworm). However, kilnsareexpensivetobuildandrun. Plain sawnQuarter sawnFigure 9.1 Plainsawingandquarter sawingHeatingpipesSteampipesOutletvalveInletvalveFanTimberstackedontrolleyFigure9.2KilnseasoningtimberKEYTERMSWarp: Become twistedor out of shape.
1159.2SourcesandoriginsTimbersourcesTimber is grownandprocessedall over theworld. Belowarethesourcesofthecommonsoftwoods andhardwoods. Table 9.4 Sources of commonsoftwoods andhardwoods. Softwood Sources Redwood (Scots pine) NorthernEurope, Scandinavia, Russia, ScotlandWestern redcedar Canada, USAParana pine SouthAmerica(mainlyBrazil) Whitewood(spruce) NorthernEurope, Canada, USAHardwood Sources Beech Europe(includingUK) Ash Europe(includingUK) ElmEurope(includingUK) Oak Europe(includingUK), Russia, PolandMahogany West Africa, e.g. Nigeria, GhanaTeak Burma, India, ThailandTheecological impactofusingtimberHumans havebeencuttingdowntrees for thousandsof yearstoclear landfor farmingandbuildingandtousethewoodfor fuel. This process is calledforestry. For thousandsof yearsthishasnotbeena problem, as theforests havecontinuedtogrowtoreplacethe trees cut down. Therefore, timber couldbedescribedasasustainable material. Over thepast hundredyearsor so, however, this has not beenthecase, andtheworld'sforestsaresteadilyshrinking. This process is calleddeforestationandit hassomeimportant consequences, suchas increasingsoil erosion. Soil erosioncauses barrenland, floodingandlandslidesaswell asdestroyingforest habitats. Forestryis sustainableaslongasforestsare allowedtoreplacethemselves, or arereplantedafter felling. The Forest StewardshipCouncil (FSC) wasestablishedin1993topromote responsiblemanagement of theworld'sforests. Itdoesthis by settingstandards onforest products, alongwithcertifyingandlabellingthemas eco-friendly. If youusetimber that isFSC-certifiedit means that it met therequirementsof theFSCcouncil andwas gatheredinanenvironmentallyresponsibleandsociallybeneficial manner. ManufacturedboardsManufacturedboards wereintroducedtohelpreducetheamountof natural timber beingused, andtheyhaveseveral advantagesover solidnatural timber: lThey arereadily availableinlarger sheetsof sizesupto2440 1 220mmfromDIYstores andtimber merchants. lThey aremorestablethannatural timber andlesslikelytotwistandwarp. lThey tendtobeless expensivethannatural timber. Figure9.3TheForestStewardshipCouncil(FSC)logo
116Chapter 9Timber VeneersSeveral manufacturedboardsmakeuseofveneers. Aveneerisathinshavingofwoodthatis either cut fromalogbyrotarypeelingorthinlyslicedfromalongblock.Veneersareoftenappliedtomanufacturedboardstoimprovetheirappearanceandgivethemasmootherfinish.PlywoodPlywoodismadeofthreeormoreveneersofwoodgluedor'laminated'together.Eachlayerofwood,orply,isgluedatrightanglestothenextinordertoincreasethestrengthofthefinishedpiece.Thereisalwaysanoddnumberoflayersorpliessothatthegrainrunsthesamewayonbothoutsidepieces.Thismeanstheboardisunlikelytobend, twistorwarp.Plywoodcanbefacedwithaveneerofdecorativehardwoodtoimproveitsappearance. Plywoodisusuallygradedforinteriororexterioruse, dependingontheglueused.Marineplywoodisusedinboatbuilding;regularplywoodisusedfordoorsanddrawerbottoms;aroughergradeofplywoodisusedinthebuildingindustry.MediumdensityfibreboardMediumdensityfibreboard(MDF)ismadebycompressingtinywoodparticles/fibresandadhesivetogether. Itisgenerallydenserthanplywoodand,comesinstandardthicknessesfrom2mmto25mm.Itisoftenpaintedorveneered, andisusedtomakeindoorfurnituresuchaswardrobes, bookcasesandcupboards.Waterproofandfire-resistantversionsareavailableforbuildingwork.BlockboardBlockboardismadebygluingstripsofsoftwoodofupto25mmsidebyside. Thesestripsarethensandwichedbetweentwoveneersofhardwood.Blockboardisusedtomakethingslikedoors, shelvesandtables.ChipboardChipboardismadebygluingwoodchipstogether. Itisafairlysoftmanufacturedboardandcancrumblewhenworkedwithorexposedtowetconditions.Therearedifferentgradesavailable: normal, mediumandhighdensity. Highdensitychipboardisoftenusedforkitchenworktops, whereit islaminatedwithmelamine(apolymer). AswithMDFtherearemoisture-andflame-resistant versionsavailable. RecyclingtimberThereareanumber of waysthattimberproductsandthewastecreatedfromproducingthemcanbeusedagain. lReclaimedtimber isthetermusedwhenoldbuildingsaretorndownandthetimberusedintheir constructionisputtootheruses, suchasflooringortomakeitemsoffurniture. Reclaimedrailwaysleepersareafavouriteoflandscapegardeners.lUpcyclingistheprocessof reusingmaterialsinsuchawayastocreateaproductofhigher value, suchasfurnituremadefromoldpallets. Itcanalsodescribetheprocessof'fresheningup' aproductbymodifyingit. a) Rotary peeling b) SlicingBladeMachinebedVeneer Blade Veneer Figure 9.4 Cuttingwoodveneers MDF Plywood ChipboardBlockboardFigure 9.5 Commonly usedmanufacturedboards KEYTERMSGrain: The textureseeninwood. Upcycling: Recyclingintoa higher-quality product.
1179.3CommonlyavailableformslDowncyclingis theoppositeof upcycling; thetimber isconvertedintoa material of lesser quality, suchasstripsfor blockboardor chips for chipboard. lBiomass is a fuel developedfromorganicmaterialssuchas scraptimber andis burnedtocreateelectricity. Eco-materialsBamboois a grass that grows quickly. Anoaktreecantake 120 years togrowtomaturitybeforeit isfelled, whilebamboocanbeharvestedinjust threeyears. It isaflexibleandlightweight material that is verystrong. It isusedpredominantly as a buildingmaterial inSouthEast Asiabutit canbe cut andlaminatedintosheets andplanksandhasbecome a popular material for designers. It isconsideredaneco-material. Figure9.6Bambooisconsideredaneco-material.Figure9.7ArangeofbambooproductsKEYPOINTSlTimberisonlyasustainablematerialifyouknowwhereintheworlditcomesfromandwhetheritssourceismaintainedandlookedafter.lUnderstandingthestructureofmanufacturedboardswillhelpyoudeterminetheirsuitabilityforarangeofproducts.ACTIVITYMake your ownmanufacturedboard: 1 Mix some woodchippings withglueuntil youhaveastodgy paste. Spreadthis betweentwosmall sheetsof cardandcompress usingavice. Leavetodryovernight. Once dry, cut intosquarechunks soyoucanseethestructure of the 'chipboard' youhavemade. 2 Dothe same experiment withwooddust andglueto formyour ownversionof MDF. Cut scrapwoodintoidentical sections andgluetogether toform'blockboard'. Addanoutsidemembranetoholdit together andtogiveit aflat surface. 9.3CommonlyavailableformsLEARNINGOUTCOMESBy theendof this sectionyoushouldknowaboutandunderstand:➜thecommonly availablestockformsof timberandmanufacturedboards➜a rangeof standardcomponentsusedtoassembleproductsmadewithtimberandmanufacturedboard. Commercial formsandsizesoftimberAfter conversionandseasoning, timber isreadytobereducedagainintosmallersectionsofcommonshapes andsizes that canbebought fromtimber merchantsandDIYstores. Thisisdone usinga rangeof bandsaws, circular sawsandplaningmachines. Timberissoldeitherroughsawnor planed. Planedtimber canbeeither planedbothsides(PBS)orplanedallround(PAR). The size of planedtimber is describedas thenominal (roughsawn) sizebut will actuallybearound3mmsmaller. PAR timber costs morethanroughsawntimber andwouldonly be usedwhereaccuracyandasmoothfinishwererequired. KEYTERMSEco-material:Anenvironmentallyfriendlymaterial.Seasoning:Adjustingthemoisturecontentoftimbertomakeitmoresuitableforuse.
118Chapter 9Timber Standard sections Decorative moulding Figure 9.10 Timber mouldings Figure9.11MDFmouldingsStrip under 100 mmwide under 50 mmthick Boardover 100mmwideupto50mmthickSquare up to 150×150Plankupto375mmwideover 50mmthickFigure 9.8 Standardtimber sections 75×75Sawn75×50Sawn69×69Par69×44ParFigure9.9TypicalplanedtimbersizesTimber canbecut intoavarietyof shapesandsizesthatareoftendescribedasplanks,boards, stripsandsquares. Withmachineryonsite, however, timberyardscanoftencuttimber toanysize/sectionrequired. Timberisusuallyavailableinlengthsof2.4mand1.8mfromDIYstoresandlonger lengthsof3.6mand4.8mfromtimberyards.lPlankisthetermgiventothelargestsections, usuallyaround50mmthickandmeasuringanywherefrom225to375mmwide. lBoardsaresmaller thanplanks, usuallynothickerthan40mmandaround100mmwideor more. lStripsaresmaller thanboards, lessthan50mmthickandnowiderthan100mm.lSquaresaresmaller still andhavethesameheightandwidth.lDowellingisasolidcylindrical rodofwoodoftencalleddowelrod.Dowelsareusedinavarietyof products, forexampleasaxlesintoys, assupportsforhangingitemslikekeyringsandasstructural reinforcementinfurniture(doweljoints).lTimbermouldingsareavailableinawidevarietyofshapesandsizesandcanbeusedfor decorativeor constructional purposes. Theyaremadebymachiningsectionsoftimber withspeciallyshapedcutters. CommercialformsandsizesofmanufacturedboardsManufacturedboardsareavailableinlargesheetsmeasuring24401220mm.Halfsheetsarealsoavailableat 12201220mm. Eachboardisavailableinavarietyofsetthicknessesdependingonthetypeof board, forexampleMDFandplywoodareavailableinthicknessesfrom3to25mmthick. MDFcanalsobeusedfor mouldingsandisavailableindifferentshapesandsizesthatcanbeveneeredor paintedandusedasdecorativearchitraveandskirting.KEYTERMSMoulding: Apre- cut sectionof timber oftenusedfor skirtingboards. Timber yard: Aplacewhere youcanbuy timber.
1199.3CommonlyavailableformsStandardcomponentsThere will betimes whenyouwill construct andassembleaproductandwill needtouseawoodscrew, handle, hingeor bracket. Theseareall examplesof pre-manufacturedstandardcomponents. Therearemanythousands of different componentsbutthissectionwilllookatexamples that couldbeimportant duringyour NEA(non-examinedassessment). WoodscrewsWoodscrews provideastrong, neat methodof fixingwoodtowood, andmetal andplastictowood, andalsofor fixinghinges, catchesandlocks. Therearemanydifferenttypesofscrew, whicharespecifiedbylength, gauge, material andtypeof head(e.g. 30mm, No. 5, brass, countersunk head). Screws aremainlymadefromsteel (cheapandstrong)orbrass(better-lookingandcorrosion-resistant). Steel screwscanbemademoreattractiveandcorrosion-resistant by galvanising, chrome-platingandblack-lacquering(calledblackjapanning). Screws havevarious types of headandscrewdriver slots: lCountersunkhead: Acountersunkheadisusedwhenyouwanttheheadofthescrewtobe level withthesurface, for examplewhenfittinghinges. lRoundhead: Aroundheadis usedtofastenthinsheetmaterialssuchasmetal orplastictowood, suchas brackets. lRaisedhead: Araisedheadis usedfor decorativepurposes, for examplewhenfittingdoor furnituresuchas handles. lTwinfast: Atwinfast is usedspecificallyonchipboardas it has twothreads, whichprovidegreater holdingpower. lCoach: Acoachis usedwheremoreholdingpower is required. It is tightenedwithaspanner. Themetalwork vices inyour workshopwill befastenedtothe benches usingcoachscrews. CapsandcupsThere are various types of caps andcups that canbeusedtocoverorenhancethelookofscrewheads. Screwcups ScrewcapsSnaps onDomeFigure 9.14 Caps andcups CountersunkRoundRaisedTwinfastCoachFigure9.12CommontypesofwoodscrewStraightslotPhillipsPozidrivFigure9.13Typesofscrewdriverslots
120Chapter 9Timber Clout nail StapleCuttackHardboardpinCorrgatedfastenersFigure 9.17 Commontypes of fasteningLength of nail Figure 9.15 Twopieces of woodfastenedwithanail NailsNailingisthequickest waytojoinpiecesofwood. Mostnailsaremadefromsteelbuttherearealsogalvanisedtypesaswell asbrassones. lRoundwirenails: Theseareusedforgeneral joineryworkandareavailableinlengthsfrom12to150mm. lOval wirenails: Theseareusedforinteriorjoinery. Theyrangeinlengthfrom12to150mm. Becausetheyhavevirtuallynohead, theycanbehiddeneasilyandfiled.lPanel pins: Theseareusedwithsmall-scaleworkandforpinningthinsheetmaterial.Theyrangeinlengthfrom12to50mm. lMasonrynails: Theseareparticularlyuseful ifyouwanttofastenintobrickworkormortar.RoundwireOval wirePanelpinMasonrynailFigure9.16CommontypesofnailOtherfasteningslCloutnails: Theseareusedtofastenroofingfelttoshedroofs.Theyaregalvanisedtoprevent rusting. lStaples: Theseareusedtomakepackingcratesandinupholsterywork.Squaretypescanbefiredfromagun, whereasroundstaplesarehammeredin.lCut tacks: Theseareusedinupholsterytofastenfabrictowoodenframes.Becauseoftheir appearancetheyareusuallyhiddeninuse. lHardboardpins: Theseareusedtofastenhardboardtoframessuchasthebackofwardrobesandbookcases. Becauseoftheirdiamond-shapedheadtheyarehiddenoncehammeredin. lCorrugatedfasteners: Theseareusedtomakequickcornerjointsinwoodenframes.Theyarehammeredacrosseachpieceofwood.
1219.3CommonlyavailableformsHingesAhinge is a moveablejoint that swings asit opensandcloses, like youwouldfindonadoor or window. Thereare several types suitablefor usewhenmakingtimber products: lButt hinges: Oneof themost commonlyusedhinges. They areusedfor doors, windows, andlargeandsmall boxes. They arecommonlymadefromsteel or brassandneedrecessingintothewood. lPianohinge: Pianohinges comeindifferent lengthsandareusedwhereyouneedalotof support alongtheedges of alongproduct. Asthenamesuggests, theyareusedonthe lids of pianos. lButterflyhinge: Usedonlightweight doors. Theyareeasytofitandlookmoreattractivethanbutt hinges. lFlushhinge: Donot needarecess tobecut, but arenotasstrongasbutthinges. lBarrel hinge: Screwedintotheedgeof thewood. Theyareeasytofitandallowdoorstobe removedeasily. StaysStays are usedondoors tocontrol howtheyopen, stayopenandclose. Stayscanbeusedwhendoors opendownwards inorder tostopthemdroppingcompletely, andtheycanalsobe usedtoholdupdoors that openupwards. DrawerandcabinetcomponentsHandlesWhenyoumakea product withasmall door or drawer youwill needahandletohelpyoupull it open. DIYstores stock hundreds of different types, availableinarangeofmaterials, finishes andstyles. Polishedbrass AnodisedaluminiumOak ChromedfinishBeech Figure 9.20 Drawer/cabinet handles Figure9.18CommontypesofhingeFigure9.19Brassstaywithadjustmentonadoorthatopensdown
122Chapter 9Timber RunnersDrawersinproductsrequirerunnerstohelpthemopenandclose.Runnersrangefromsimplenylonpiecesfixedtothesidethatruninagroove, tocomplicatedmetalrunnersthatsupport thewholedrawer asitispulledout(extensionrunners).Figure 9.21 Metal extensionrunners andnylondrawerrunnersDoor runnersarerequiredwhenslidingglassorplasticdoorsareused.Theseareextrudedplastic'channelling' that isfixedtothetopandbottomofthecabinet.LocksThereareseveral differenttypesof lockavailablethatyoucouldincorporateintoyourproducts: lHaspandstaple- areusedwithpadlockstofastensheddoorsandgates.lCamlocks- haveatabthatturnsandcatchesinaslot; theyareusedindisplaycabinets.lMagneticlocks- arehiddenlocksthatcanrequireamagnetickeytoopen;theyareoftenusedto'childproof' cupboards. Figure9.22PlasticrunnersHasp and staple CamMagneticFigure 9.23 Different locks
1239.3CommonlyavailableformsCatchesCatches are usedtokeeplids closedonboxesor doorsshutoncabinets. Theyareavailableina range of materials dependingonthetypeof product theywill beusedon. lMagnetic catches - areverycommonandareavailableinarangeofmaterials. Polymerones canbefoundonkitchencabinets, whilehighendcabinetworkwoulduseonesmade frombrass. lSpringcatches - t endtobeusedonmorefunctional itemsastheyarenotasattractive. lBall catches - c anberecessedintodoorsandareveryneat. Theyareavailableinarange of sizes. lTogglecatches - canbeusedtofastenthetopandbottomof aproducttogether. Magnetic catch SpringcatchBall catchTogglecatchFigure9.24CommontypesofcatchKEYPOINTAn awareness of thedifferent components availablefor useontimberproductswill helpinformyour designdecisions whenyouaredevelopingideas. ACTIVITY1 Prepare a stock list of thewoodmaterials inyour workshop. Presentthisintheformof a table andincludedetails suchas: nameof timber; typeofwood(hardwoodorsoftwood); forms andsizes; typeandthicknessof manufacturedboards;shapesoftimber mouldings. 2 Visit your local DIYstoreandlookat thetimber for salethere. lHowmuchdifferenceis therebetweenthepricesof sawntimberandplanedtimber?lWhy doyouthinkthereis this difference?lHowmany different shapes of timber mouldingsdoesthestoresell?
124Chapter 9Timber 9.4ManipulatingandjoiningLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstandtheuseofspecialist techniquestoshape,fabricate,constructandassemblehighqualityprototypesfromtimberandmanufacturedboard,including:➜wastage➜addition➜deforming.WastageWastageinvolvescuttingmaterialstotheshaperequiredandremovinganyexcessmaterial.It includesprocessessuchassawing, drilling, filing, sandingandturning.Marking-outtoolsBeforecutting, bending, shapingandjoiningmaterialsyouwillneedtomarkoutyourdesign. Markingout accuratelyisimportanttoensuredifferentpartsfittogethercorrectly.Arangeof toolscanbeusedwhenmarkingout. MarkingknifeThis is usedtomarklinesonapieceoftimber. Itisthinnerthanapencilmarkandcansometimeshelpguideyouwhensawing. Marksaremadeacrossthegrainandasharppencilcansometimesbeusedinsidethelinetomakeitshowupmoreclearly.TrysquareAtrysquareisusedtomarkalineat90degreestoanedge. Itcanalsobeusedtotesthowsquareanedgeisbyplacingitonthecorner.MarkinggaugeThisisusedontimbertodrawalinealongthegrain,parallel toanedge, usingasharppointcalledaspur.CuttinggaugeThisisusedonwoodtodrawalineacrossthegrain,parallel toanend. Itisdifferenttoamarkinggaugeinthatitusesasmallbladetomarkacrossthewood,likeapizzacutter. MortisegaugeThisisusedinthesamewayasamarkinggauge,butithastwospursthatcanbeadjustedtomarkoutthemortiseortenononawoodjoint.MitresquareThisisusedontimbertomarkoutormeasureanglesof45or135degrees. SlidingbevelThiscanbesettoanyangle,usingaprotractor,andthentightenedinposition. Edge of wood MarkinggaugeSpur Line markedparallel toedge Figure 9.26 MarkinggaugeFigure 9.25 Try square
1259.4ManipulatingandjoiningFigure 9.27 Mitre squareFigure9.28SlidingbevelSawsA'handsaw' is thegeneral namefor asawusedtocut largepiecesof timberbyhand. lAcross-cut sawis usedtocut across thegrain. lAripsawis usedtocut alongthegrain. lTenonsaws aregeneral purposesawsthat areverygoodatmakingstraightcutsintimber. lCopingsaws areusedtocut curves inthinpiecesof timber. Length500-700mmLength250-350mmLever pins to change position of blade Length150mmSprung steel frame CopingsawTenonsawHandsawTeeth Toe Heel Blade HandleHandleof beechorpolypropyleneBeechorpolypropylenehandleistightenedtotensionthebladeFigure 9.29 Handsaw, tenonsawandcopingsaw
126Chapter 9Timber Awoodworker'sviceisusedtosecuretheworkpiecewhenusingtenonandcopingsaws.Abenchhookcouldbeusedtocutsmallerpiecesoftimber. lAjigsawisanelectricsawandisuseful forcuttingshapesfrommanufacturedboard.Fine, mediumandcoarsebladesareavailablefordifferentpurposes.Theworkisusuallyheldacrossaworkbenchtomakeiteasiertocut. lAfretsawisasmall electrical sawthatisfixedtoabenchandusedforcuttingcurvesinthinmaterial. Thebladeusedisthinandmovesquicklyupanddowntocutthroughthework, soit isimportantthatthepieceisheldfirmly. lAbandsawisalarge, heavydutyelectrical sawwithaband-shapedmetalbladeforcuttingirregular shapesintimberandmanufacturedboard.Thewidthofthebladedetermineshowtightacurvecanbecut. Portableversionsareavailable,whicharefixedtobenches. Larger modelsarefreestandingandfixedtothefloor.lAcircularsawisanotherlargeheavydutyelectricalsaw,anditusesacircularbladefor cuttingtimber andmanufacturedboard. Smallerhandheldmodelsareusedwhereportabilityisneeded. Largerfreestandingsawsareoftenusedonbuildingjobs,andevenlarger versionscalledtablesawsareusedinfactoriesandworkshops.Figure 9.30 Jigsaw, fret saw, bandsawandcircular saw
1279.4ManipulatingandjoiningDrillsanddrill bitsThere are many different types of drills anddrill bitsusedwhendrillingholesintimberandmanufacturedboard. Thedrills anddrill bitscanbeheldeitherinahanddrill, aportabledrill, a drillingmachine, or acentrelathe. lTwist bits arethemost commontypeof drill bit andareusedfordrillingholesintimber, metal andplastic. lCountersinkbits providethecountersunkshapefor screwssotheydonotprotrudefromthesurface. lForstner bits providesmooth-sided, flat-bottomedholes. lFlat bits providefast andaccuratedrillinginsolidpiecesof timber. lHolesaws haveinterchangeablecuttingbladesthat enableyoutodrill holesof20-75mmdiameter. lExpansivebits canbeadjustedtodrill shallowholesinwoodof 12-150mmdiameter. Portable electric drill Cordlessrechargeabledrill Wheel braceor handdrill BenchdrillorpillardrillMachinebedDrillbitChuck KEYPOINTSAdvice whendrillingholes: lMake sure that your workis secure. Trynot toholdyour workwithyourfingerswhenusingthe drillingmachine. lMake sure that thedrill bit is tight inthechuck, removethekeyandensurethatthesafety guardis inplace. lIf youare drillingstraight throughmaterial, placescrapwoodunderneathtodrill into.lWhendrillinglarge-diameter holes, drill a'pilot' holefirst. FilingFiles are madefromhardenedandtemperedhigh-carbonsteel. Theycanbeusedtoshapeandremove/wastetimber andsomemanufacturedboards. Filesareclassifiedbylength, shape andcut. There are various grades of files: roughandbastardcutsfor coarsework; secondcutforgeneral use; andsmoothanddeadsmoothfor veryfineworkbeforepolishing. Theshapeofeachfile is designedtobeusedtoproduceasimilar shapeonthematerial itiscutting. Thereare flat, round, curved, squareandtriangular shapedfiles. Ahandfilehasaflatedgewithoutany teeththat allows it tofileaccuratelyina90-degreecorner. Figure9.31Handdrillsandelectricdrillingmachines
128Chapter 9Timber Needlefilesaresmall filesusedforintricateworkandareavailableinawidevarietyofshapesfor different purposes. Surfacingformingtools(surformtools)Surformtoolshaveacuttingactionsimilartoacheesegraterandcanremovewoodveryquickly. Themost commonshapedbladesareflat, curvedandround.ChisellingChisels areusedtoremovesmall amountsofwood. Chiselsaremainlyusedwhencuttingajoint inwood. Threebasictypesof chisel areused: thefirmerchiselisageneralall-purposechisel that hasflat sidesandisusedwithamallet. Thebevel-edgechiselhasbevelledorslopingedgesthat allowittobeusedincorners, forexample,whencuttingoutadovetailjoint. Themortisechisel hasathicker bladetolever outwastewithout thewoodbreaking. It isdesignedtobehit withamallet. Firmerchisel Firmer-typehandle(ash, beechorcelluloseacetate) TangShoulderBrassferruletopreventsplittingBladeofhardenedandtemperedtool steel CuttingedgeCarver-typehandle(boxwoodorpolypropylene)LeathershockabsorbingwasherStrongerneckandshoulderThickerbladeBevel-edgeBevel-edgefirmerchiselMortisechiselKEYPOINTAdvice whenfiling: lCross filinguses the full lengthof the file andis usedtoremove wastequickly but does not leave a smoothsurface. lDrawfilingis usedtoproducea smoothsurfaceafter cross filing. Only part of thefile is usedsovery little material is removed. RoundFlat or curvedinterchangeablebladeFigure9.33Surformtools Figure9.34Typesofchisel1/3LHandleofbeech,ashorplasticsSteelferruleFlat fileHand Flat Half-roundRoundorrat-tailFour-squareThree-square Blade of highquality carbon steel hardenedandtemperedTeeth Safe edgeTangHandfile Parts of a file Knife-edgeWarding(ahalfthicknessflatfileforfilingnarrowslots)Figure9.32Types of files
1299.4ManipulatingandjoiningKEYPOINTAdvice whenchiselling: lChisels canbe hit withamallet or manipulatedbyhand. Paringdescribeschiselsthatareusedwithhandpressureonly. lSafety is essential, andthemost important ruleisthat youmustkeepbothhandsbehindthe cuttingedgeof thechisel at all times. lHorizontal paringis whenthewoodsecuredinavice. Youwouldusehorizontal paringto cut out a halvingor housingjoint. lVertical paringfromaboverequires considerablepressureandaGcrampisneededtosecure the wood. Youmay needtouseamallet toprovideenoughforcetocutthroughthe fibres of the wood. PlaningPlaningis carriedout toremoveexcess woodandtoproduceasmoothsurfacefinish. Thecuttingactionof a planeis similar tothat of achisel heldinaframeataspecificangle. Thetwomost commonplanes areJackplanesandSmoothingplanes. lSmoothingplanes areabout 250mmlong; theyhaveabladethatisgroundandsharpenedfor finefinishingandfor planingendgrain. lJack planes arelonger andheavier andareusedfor thequickremoval ofwastewoodtomake surfaces flat andtoachievetherequiredsize. There are other 'special' planes that youmayseeinaworkshop. lBullnoseplanes areusedtoplainintocornerslRebate planes cut out rebates or groovesalongtheedgesof timberpieces. lRouter planes areusedtocut out grovesacrossthegrainof wood. lSpoke shavers canusedtoroundtheedgesoncurvedpiecesof timberSmooth plane JackplaneFigure 9.35Types of planeRebateplaneRouterplanePloughplaneShoulderplaneFigure9.36SpecialplanesKEYPOINTAdvice whenplaning: lAlways plane alongthegrain, otherwiseyouwill tear thesurfaceofthewood.lWhenplaningtheedgeof apieceof timber it isimportanttosecurethewoodinavice.lWhenplaninglongthinstrips of wooduseabenchstop, asthebenchitselfwill supportthe stripandstopit frombending. lWhenplaningendgrainthereis ahighchancethat theworkwill splitwhentheplanegoesacross the edge. If theworkis longenoughplanefromtheedgetothemiddle.Otherwiseconsider crampingor gluingasmall pieceof woodtotheendthatwill takethedamage.
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132Chapter 9Timber Between-centresturningBetween-centresturningisusedtomakeproductssuchasrollingpinsandchairlegs.Youbeginwithasquaresectionoftimberwhichhashadthecornersplanedoffandasawcutacrosstheend(thismakesiteasiertostart).Aforkcentre(speciallyshapedtogripthepiece)isheldinahollowspindleontheheadstockofthelathe.Thisisconnecteddirectlytothemotorandturnsthepieceoftimber. Adeadcentre(shapedtoallowthepiecetospinfreely)isheldinthetailstockattheoppositeend.Thetailstockismoveddowntotheworkpiece,whichisheldfirmlybetweenboththeheadstockandtailstock.Asthetimberturns, toolsareplacedontherestandmovedtowardsittocutandcarveshapesintoit.FaceplateturningFaceplateturningisusedtomakeproductssuchasbowls.Thetimberusedforfaceplateturningisbiggerandflatterthanthatusedforbetween-centresturning.Theworkpieceisscrewedtoafaceplate, whichisconnectedtotheoutersideoftheheadstock. Speciallyshapedtoolrestsareusedtoallowtheusertogettheircuttingtoolsinsidethework.Lathetoolsarecalledchiselsbuttheydifferfromtheonesdescribedearlierinthischapter.Theyfeaturelong,round,curvedhandlesthatofferabettergripandsufficientleveragetoenabletheturnertocontrolthecuttingedgeaccurately. Thereareseveraldifferenttypesofturningtool:lGouges: Theseusuallyhavespeciallyshapedcuttingedgesforperformingparticularcuts, suchasbowl gouges, withconcave, curvedcuttingedgestoformthesmooth,curvedsurfaceof abowl. lScrapers: Theseareoftenflatorslightlycurvedchiselsforremovingwoodfromflatorcylindrical shapes, or for roughingoutashape. lPartingtools: Thesearethin, vee-tippedtoolsforcuttingoffworkpieces.lSpooncuttershaveaspoon-shapedcuttingedgeandarealsooftenusedforshapingbowls. lOther toolsyoumayencounterareskewchisels, flutedgouges,spindlegouges,andnosechisels. RoutingApower router isanextremelyuseful andversatiletoolthatisusedforcuttinggroovesintimber andmanufacturedboard. Ahigh-speedcutterisplungedintothematerialandthenmovedaround. It canbeusedwithguidesforstraightlinesandwithtemplatesformorecomplexshapes. Differentshapedcutterscanbeusedtocutdifferentshapedgroovesortoproducedecorativeedges. Atablerouterisastationaryversionofarouter.Itismountedunderneaththeworksurfacewiththecuttingtool protrudingupwards.Piecesofworkcanbepushedagainst thecutter. Afenceisoftenusedtoguidethemovementonstraightpieces.Sawcuts - chisel out centrePlaneoff cornersFork centre CandlewaxCentretailstockFigure9.41Between-centres turningFigure9.42Turningabowl usinga faceplate
1339.4ManipulatingandjoiningDepth stop Collet toholdcutter Routing base FenceguideAdjustable Dust extractionfence Table Router Rebate cut with straight bit Profilecut withRomanOgeepieceFigure 9.43Ahandheldrouter andatablerouter Panel pilotbitwithdrillpointStraightbitVgroovingbitDovetail bitCoveboxbitFigure9.44Typesofroutingbits/cutters
134Chapter 9Timber AdditionAdditionprocessessuchasadhesionandjoiningareusedtojoinmaterialstogether.NailingWhenyounail atimber frametogether, youshouldstaggerthepositionsofthenails.Thiswill helptoavoidsplittingthetimberalongthegrain. Hammeringtwonailsintomaterialsatoppositeangleswillmakethejointstrongerandmoredifficult topull apart. Thisiscalleda'dovetailing' nailing. Figure 9.45 StaggerednailingFigure9.46DovetailnailingScrewingWhenscrewingtogether twopiecesoftimberapilothole(whichissmallerthanthecoreof thescrew) andaclearancehole(whichisslightlybiggerthantheshankofthescrew)arescrewed. Whenusingcountersunkscrews, thescrewheadsitsinacountersinkwhichislevelwiththesurfaceof thewood, asshowninFigure6.48. 1Drill apilot hole. 2Drill aclearancehole. 3Drill thecountersunkfor theheadto'sit' in. 123Figure9.47Preparingtwopiecesoftimbertobescrewedtogetherwithcountersunkscrews
1359.4ManipulatingandjoiningWoodjointsInadditiontousingphysical componentstojoinworktogether, timbercanalsobemanipulatedtocreatespecificjoints tomaintainastructure. Joint IllustrationDescriptionExampleusesButt Flushdoor ButtCorner halvingCross halvingMitrejoint Asimplejoint inwhichtwopiecesoftimber arejoinedbyplacingtheirendstogether andnailingorgluingthem.Thisjoint canbeveryweakandisoftenstrengthenedwithcornerpiecesorafastener. Basicboxesorcabinets,buildingframes.Dowel BridlejointSquare haunchmortise andtenonEnds of tenonmitredDowel joint HaunchAseriesof correspondingholesaredrilledinthejointsurfaceoftwopiecesof timber. Shortdowelsaretheninsertedwithglueandthejointisclampedtogether until dry. Accuracywhendrillingholesisimportanttomakesurethetwopiecesof woodjoinup. Chairandtablelegs,tabletops,cabinetsandpanels.Comb or finger Madebycuttingrectangularcutsintwopiecesof timber, whichinterlockat90°aangle(likeyourfingers)whenglued.Tablesandchairs,floorboards,roofanddoorconstruction.Dovetail Pinsarecut inonepieceoftimberandinterlockwithaseriesoftailscutinanother pieceof timber. Thesearegluedtogether. Thejointisveryresistanttobeingpulledapart. Joiningthesidesofadrawertothefront,jewelleryboxes,cabinets.Half-lap Butt joint Half-lapjoint HousingjointsStoppedhousingPlywoodkey Dowelledbutt joint Dovetail nailingTwopiecesof piecesoftimbertogetherbyoverlappingthem. Material isremovedfromeachpieceoftimberat thepoint of intersection.Thisjointisoftenreinforcedwithdowelsorfasteningssuchasnails. Framing
136Chapter 9Timber Joint IllustrationDescriptionExampleusesMitre Ajoint madebycuttingthetwopiecesof timber tobejoinedatanangleof45°,sothat a90°cornerisformed.Mitrejointsarequiteweaksokeyscanbeusedtoreinforcethem.Pictureframes,pipes,moulding,HousingHousingjointsStoppedhousingAjoint madebycuttingachannelinapieceof timberandinsertingandsecuringanotherpieceoftimberintothechannel. It canbeusedwithmanufacturedboardssuchasMDFandparticleboard.FittingshelvesandpartitionsintobookcasesandcabinetsMortise and tenon Ajoint comprisingofamortiseholeandatenontongue. Thetenoniscutinonepieceof timber(knownastherail)tofitexactlyintothemortiseholeintheotherpieceof timber. Thisisastrongjoint.TableandchairlegsBridle Bridlejoint Square haunch mortise and tenon Ends of tenonmitredDowel joint Haunch Similar toamortiseandtenonjointbut withalongertenon(aslongasthedepthof thetimber)andamortisethatiscut tothewholedepthofthetimbersothat thetwopiecesoftimberlocktogether tightly. Itisslightlystrongerthanthemortiseandtenon,butlessattractiveastheendgrainofthetenonisvisible. Legsorstilestorails,framesCorner hFlau lsvh indgoor ButtCorner halvingCross halving Ajoint inwhichchannelsthatinterlockarecut intothecorneroftwopiecesoftimber. Theyareoftengluedandnailedor screwedtoreinforcethem.Frames
1379.4ManipulatingandjoiningJoint IllustrationDescriptionExampleusesCross- halving Butt Cross halvingMitrejointConstructedinthesamewayasthecorner halvingjoint, butthejointismadeinthemiddleofthetimbertoallowanyinternal partsoftheframeto'cross' eachotherinsidetheframe.Strengtheningrailsfortablesandchairs,trellis,boxcompartmentdividersBiscuit Small slotsarecutintotheedgesoftheboardsusingabiscuitjoiner.Anoval-shapedcompressedwoodfibrebiscuitisthengluedintotheslotandthetwoboardsareclampedtogetherThisjoint canbeusedwithmanufacturedboardssuchasMDFandparticleboard. TabletopsJoints usedintheconstructionof timber productscanbebroadlyclassifiedintothreegroups: carcaseor box construction(jointsthat couldbeusedatthecornersofaproduct), frame construction(usedtomakedoors andwindows) andstool construction(usedwhenmakingsmall stools or tables andjoiningrailstolegs). Cabinet Box BasicframeconstructionFramewithcrossrailsFigure 9.48 Box, stool andframeconstructionDeformingandreformingDeformingandreformingis theprocess of changingtheshapeof timber. Itincludesprocesses suchas steamingandpressingBendingAvery basic methodof bendingtimber intocurvesiscalledkerfing. Puttingaseriesofevenly spacedsawcuts onthebackof thetimber allowsthepiecetobebent. Thismethodis really suitableonly if just onesideof thecurveistobevisible, suchasforthecurvedbodySTRETCHANDCHALLENGEWorkingwithapartner,cuttwelvepiecesoftimber60x60x20mm.Selectsixdifferentjointsfromthetableaboveandmakethreeeachusingthesepiecesoftimber.Discusstheprocessesusedandtheadvantagesanddisadvantagesofeachjoint.Photographthejointsyouhavemadeandcreatearesourcesheetforuselowerdownintheschool.Createaskillsboardwithexamplesofaselectionofdifferentjointssuitableforbox,frameandstoolconstruction.KEYTERMSKerfing:Makingsawcutssothatwoodcanbend.
138Chapter 9Timber of aguitar. Theprinciplehasalsobeenappliedtomanufacturedboards,withversionsofflexible(bendy) MDFandplywoodavailableforlargerprojectssuchasacurvedreceptiondeskor shopcounter. KerfingBendingFigure9.49KerfingwoodSteambendingAnothermethodofdeformingtimberthathasbeenusedformanyyearsissteambending.Thisinvolvesplacingthetimberpieceinasealedboxthatiskeptfilledwithsteam. Asthetimberabsorbsthehotmoistureitbecomessofterandeasiertobend.Thesteamedtimberisbentintotherequiredshapearoundaspecialformerandclampedfirmlyinplacesothatitkeepsitsshapewhileitdriesout.Theshapedwoodneedstodryoutthoroughlybeforeitisunclamped.LaminatingAnothermethodofproducingcurvedshapesinwoodislaminating. Thinlayersofwood(calledveneers)aregluedtogetherandheldaroundaformeruntilthegluesets. FormerscanbeheldtogetherwithGorsashclampsandflexiblesteelbands. VacuumpressingOne-sidedformerscanbeusedwithavacuumbag, whichisconnectedtoapumpthatremovestheair frominside. Thisallowsairpressureontheoutsidetoholdtheveneersinplaceasthegluedries. Blank Steambox Steamin Fixedformer Finishedpart Removableformer Figure 9.50 Steambendingtimber Clamp in vice Simple former Strips of rubber WaxedclampingblocksFixedformingLaminating chair legs blocks ClampBeddesignedtoallowairremoval Highdensityexpandedpolystyrenemouldwith1mmlaminategluedtosurfacelaminatesSealedPVCbagPorousmaterialusedtoensurevalvecannotbeblockedAirextractedFigure 9.51 Laminatingwoodenshapes usingaformerandavacuumbagKEYTERMSFormer: Ablockmadetoholdmaterial intheshape required. Laminating: Buildingupa shape inthinlayers. Steambending: Softeningthe fibres of woodwithsteamtoallowit tobend.
1399.5Structuralintegrity9.5Structural integrityLEARNINGOUTCOMESBy theendof this sectionyoushouldknowaboutandunderstandhowandwhytimber/manufacturedboardproductsneedtobereinforcedtowithstandforcesandstresses. Also, theprocesses that canbeusedtoensurethestructural integrityofaproduct,including: ➜howtriangulationis usedtoreinforcetimberproductsandstructures➜howknock-downfittings canbeusedtoreinforceproductsmadefrommanufacturedboard. Trees are livingstructures andtheygrowbyproducinghollowtubelike cells composedmainlyof cellulose. Softwoodsarecomposedalmost entirely of tube-likecells, whereas hardwoodshaveamorecomplex structure. Somecontainfibrous material, whichaddsmechanical strengthandmakes thewoodharder. Froma structural point of viewall timber canbethought of asbundlesof parallel tubes, likeabundleof drinkingstraws. Thesetubesaremade fromthesamematerial but havevaryingwall thicknesses. Thetensilestrengthof woodingeneral is quitehigh. Weightfor weight, some timbers haveatensilestrengthgreater thanmildsteel. The compressivestrengthof timber is muchlower. Woodisalsovery weak across thegraininterms of tensionandcompression. Hardwoods tendtobestiffer thansoftwoodsbecauseof their fibrecontent. Youmust remember, however, that theterms'hardwood' and'softwood' relatetothetrees theycomefromandnot totheirmechanical properties. Figure9.52AmagnifiedsectionofwoodFigure9.53TriangulationinrooftrussesandthebackofasheddoorTriangulationMaintainingstructural integrityintimber productsdependsonhowwell individual piecesare joinedtogether, andas suchwoodjointsarelookedat specificallyinalatersection(seeSection6.7, page149). Thebasicprincipleof triangulation, however, canbeappliedtovarioustimber products suchas gates androof trusses. Triangulationinvolvesusingtriangularshapestogive stability tostructures. Timber frameproducts canalsobereinforcedbyusingtheprincipleof triangulationorbyusingpremadecomponents suchas T-plates, flat corner ironsandcornerbraces. KEYTERMSCellulose:Anorganiccompound,structurallyimportantinplantlife.Compressivestrength:Theresistanceofamaterialfrombreakingcompression/squashing.Tensilestrength:Theresistanceofamaterialtobreakingundertension/stretching.
140Chapter 9Timber Bolt Pins T-plate Corner braces Knock-downfittingsKnock-down(KD) fittingsareamodernwayofjoiningmaterialsquicklyandeasilywithouttheuseof clampsandglue. Theyallowproductstobedismantledandassembledwhenevernecessaryandreinforceproducts' structural integrity. KDfittingsthereforeallowforproductssuchas wardrobesandkitchenunitstobesoldasflatpacksandassembledathome.KDfittingsprovidesimpleconstructiontechniquesformaterialssuchaslaminatedMDFandchipboard. TheremanydifferenttypesofKDfittingavailableandseveralincludetheuseofdowel or metal pinstolocatepartof thejoint. Mostcanbefittedwithbasictoolssuchasahammer, screwdriver anddrill. Figure 9.54 Different ways to reinforcetimber frame structures TwoblockfittingTwoblockfittingsaremadefromplastic. Aboltpassesthroughthefirstfittingintothethreadofthesecond. Astheboltistighteneditdrawsthetwofittingstogether. Thepinshelpkeepthefittingstraight.Thisgivesaverystrongjointanditcanbedismantledusingascrewdriver.RigidjointThesearenormallymouldedinplastic, whichmakesthemstrong.Screwspassthroughthefourholes, whichholdthesidesateachcornerfirmlytogether. ConnectorboltThesefastenershavea6mmthreadsystemandareusedtojoinwardrobesandcabinetstogether. Astheboltheadwillbevisible,theyhaveabrassoranodisedfinish. Theyareusedwithascrewthatispushedthroughfromtheoppositeside. ThefasteneristhentightenedwithanAllenkey.Figure9.56ArigidjointFlat corner ironPlywoodgussetWoodblockFigure 9.55 AtwoblockfittingBolt Pins ThreadPinsFigure9.57Aconnectorbolt
1419.5StructuralintegrityACTIVITY1Takeabundleofartstrawsandgluethemtogetherlengthwaystoexplorethestructuralstrengthofwood.Experimentwiththembyhangingweightsontheendofthestring(tension),cuttingshortstrawsandstandingonabundleofthem(compression)andbendingthem.2Createaskillsboardwithexamplesofdifferentknock-downfittings.3Createaseriesofstructuresbyhotgluingsmallpiecesofwoodsectionstogether-experimentwithdifferentwaystoreinforcethejoints.Whichmethodisthemostsuccessful.CrossdowelsThese are strongenoughtobeeither permanent or temporaryjoints. Thecylinderisinsertedintothe first sideof acabinet inapre-drilledhole. Thescrewisthenpushedthroughthehole inthe secondsideuntil it meets thecylinder. It canthenbetightenedwithanAllenkeyuntil bothsides of thecabinet pull together. Rail AllenscrewLocating pin LegAluminiumbarrel Figure 9.58 Across dowel ScrewdriverslotThreadedrodInsideofdrawerDrawerfrontFigure9.59AcamlockCamlocksThe disc fits intoa recess inthefirst sideof thecabinet. It isrotatedbyinsertinga screwdriver intotheslot inits side. Theshaft isscrewedintothesecondsideof the cabinet. Thecollar of theshaft is passedthroughtheholeinthesecondslot inthe disk. Whenthediskis rotatedtheshaft islockedinposition. Thiskeeps bothsides of thecabinet lockedtogether. BenchtopjoinersBenchtopjoiners areusedtotemporarilyjoinlargeflat piecesof wood. Aflat hole is drilledineachpiecewithaflat channel toallowthebolttopassthrough. Thejoiner is theninsertedandtightenedupusingaspanner. TableplateThe 'table plate' fittingis usedtoassemblerailstolegsinflatpacktables. Figure9.60AbenchtopjoinerFigure 9.61 Atable plateKEYPOINTThink carefully about howyour product will beassembledanddisassembled.Will it remainstructurally soundwhenit's put together?
142Chapter 9Timber 9.6MakingiterativemodelsLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstand:➜theprocessesandtechniquesthatcanbeusedtoproduceearlymodelsmadefromtimber andmanufacturedboard➜howtheuseoftimberandmanufacturedboardcansupportiterativemodelling.Timber andmanufacturedboardcanbeusedinavarietyofusefulandinterestingwaystohelpyouexploreyour earlydesignideasandtosupportiterativedesigninginschool.SheetmaterialsSheet materialsareexcellentfordevelopinginitial ideas. Theyarequickandeasytoworkandarenot tooexpensive. MDFMDFis availableinarangeof differentthicknesses. Thinnersheetsof2to10mmcanbemanipulatedfairlyquicklyinaworkshoptoproduceearlymodels.MDFcanbecutbyhandwithacopingsawor bymachineusingafretsaworbandsaw.AspecialgradeofMDFsuitablefor laser cuttingisneededformoreaccurate/intricatework.Figure9.62Amodel madeusingathinsheetofMDF,dowelandsquaresectionPlywoodThinner sheetsof plywoodcanalsobeusedforquickmodelsbutthefinishwillnotbeasgoodaswithMDF, sinceplywoodtendstosplinter. LikeMDF,aspecialgradeof'LaserPly'isneededfor workonthelasercutter. LaserPlyisbondedwithspeciallymodifiedadhesivesthat producelesssmokewhencutting, whichisnecessaryassmokereducestheefficiencyofthelaser.
140Chapter 9Timber Bolt Pins T-plate Corner braces Knock-downfittingsKnock-down(KD) fittingsareamodernwayofjoiningmaterialsquicklyandeasilywithouttheuseof clampsandglue. Theyallowproductstobedismantledandassembledwhenevernecessaryandreinforceproducts' structural integrity. KDfittingsthereforeallowforproductssuchas wardrobesandkitchenunitstobesoldasflatpacksandassembledathome.KDfittingsprovidesimpleconstructiontechniquesformaterialssuchaslaminatedMDFandchipboard. TheremanydifferenttypesofKDfittingavailableandseveralincludetheuseofdowel or metal pinstolocatepartof thejoint. Mostcanbefittedwithbasictoolssuchasahammer, screwdriver anddrill. Figure 9.54 Different ways to reinforcetimber frame structures TwoblockfittingTwoblockfittingsaremadefromplastic. Aboltpassesthroughthefirstfittingintothethreadofthesecond. Astheboltistighteneditdrawsthetwofittingstogether. Thepinshelpkeepthefittingstraight.Thisgivesaverystrongjointanditcanbedismantledusingascrewdriver.RigidjointThesearenormallymouldedinplastic, whichmakesthemstrong.Screwspassthroughthefourholes, whichholdthesidesateachcornerfirmlytogether. ConnectorboltThesefastenershavea6mmthreadsystemandareusedtojoinwardrobesandcabinetstogether. Astheboltheadwillbevisible,theyhaveabrassoranodisedfinish. Theyareusedwithascrewthatispushedthroughfromtheoppositeside. ThefasteneristhentightenedwithanAllenkey.Figure9.56ArigidjointFlat corner ironPlywoodgussetWoodblockFigure 9.55 AtwoblockfittingBolt Pins ThreadPinsFigure9.57Aconnectorbolt
144Chapter 9Timber 9.7FinishesLEARNINGOUTCOMESBytheendof thissectionyoushouldknowaboutandunderstandtheprocessesusedfor finishingandaddingsurfacetreatmentstomaterialsandproductsforspecificpurposes, including: ➜function➜environmental factors➜aesthetics. Therearetworeasonstoaddafinishtotimberproducts: lAesthetics: Youwanttoimprovehowtheproductlooks.Thiscouldbetoenhancethenatural lookof thetimberortochangeitscolour. lFunction: Youwant toprotecttheproductfromdamagebyincreasingitsdurabilityandprotectingit fromenvironmental factorssuchasmoistureandsunlight.PreparingtimberforfinishingSandingshouldbekept toaminimum(especiallyonhardwoods),souseaplanetoachievethebest possiblefinishbeforesanding. lUseabrasivepaper wrappedaroundacorkblocktoavoiddamagetothewood.lSandwithmoderatepressureandalwaysinthedirectionofthegrain.lTakecarenot toroundcornersorrubhollowsinflatsurfaces.lSandwithcoarsepaper atfirst, workingdownthroughthegradesandfinishingwithafinepaper. lUseafinebrushinthedirectionofthegraintoremovethedustaftersanding.Figure 9.64 Usingabrasivepaper on timber AbrasivesTherearethreetypesofabrasivethatyoucanuseontimber:lGlasspaper-consistsofgroundglass,gradedintosizesandgluedontobackingpaper.Sheetsizeis280230mm. lGarnetpaper-consistsofhardstone,crushed,gradedandgluedontobackingpaper.Itismoreexpensivethanglasspaper.lWirewool-usedasaveryfineabrasiveinthefinalstagesofpolishing. GradesofabrasiveAbrasivesaregradedaccordingtothesizeoftheparticleswithinthem. Thesesizesarereferredtoasgrits.lExtrafine:Thisgradeofsandpaperisusedbetweencoatsofpaintorvarnish.Gritsof240,320and400aretermedveryfine, whileextra-orsuperfinesheetswithgritsofupto600areavailableforpolishingjobs.lFine: Fineabrasivepapershaveagritrangeof120to220.Formostworkshops,finewillsufficefor final sandingbeforetheworkisfinished. lMedium: Somefinal shapingcanbedonewithmedium,whichhasagritrangeof60to100. General sandingworkisoftenbestdonewithmedium-gradesandpaper.lCoarse: Roughshapingisdonewithcoarsepaper, asistheremovalofpreviousfinishes.Thegritsaretypicallyinthe40to50range. lExtracoarse: Thisstuff isreallyrough, usedforremovingpaintandvarnishthatyouthinkmight never comeoff. Thesandingofoldfloorsalsosometimesrequiresextracoarsesandpaper. Onlytobeusedonthetoughestjobs.