Sketching

Sketchingisoneofmanydraftingtechniques.Itisaquickwaytoshowanideathatwouldbedifficulttodescribewithwordsalone.Industryusesmanysketchingtechniquestodevelopengineeringconcepts.Agoodsketchshowstheshapeoftheobject.Italsoprovidesdimensionsandmayincludespecialinstructionsonhowtheobjectistobemadeorfinished.ProperSketchingEquipment:

- ProperlysharpenedF,2HorHBpencils- Standard-sizepaper(8.5X11)- Agooderaser

HowtoproperlySketch

Insketching,alineisdrawnbymakingaseriesofshortstrokes.Itisrecommendedthatlight(thin)constructionlinesbedrawnfirstsocorrectionswillbeeasiertomake.

- Forright-handedpeople,yourlineswillbedrawnfromlefttoright.Verticallineswillbedrawnfromthetopdown.

- Theoppositeistrueforleft-handedpeople.

AlphabetofLines

Adrafteruseslinesofvariousweights(thickness)tomakeadrawing.Eachlinehasaspecialmeaningascontrastbetweenthevariouslineweightsorthicknesseshelptomakedrawingeasiertoread.ConstructionandGuideLine

- Constructionlinesareusedtolayoutdrawings.Guidelinesareusedinletteringto

helptokeeptheletteringuniforminheight.Theselinesaredrawnlightlyusingapencilwiththeleadsharpenedtoalongpoint.

BorderLine

- Theborderlineistheheaviest(thickest)lineusedinsketching.First,drawlight

constructionlinesasaguide.Then,gooverthemusingapencilwiththeheavyroundedpointtoprovidetheborderlines.

ObjectLine

- Theobjectlineisaheavylinebutslightlylessinthicknessthantheborderline.The

objectlineindicatesvisibleedges.Insketchingobjectlines,useapencilwiththemediumleadandaroundedpoint.

HiddenLine

- Hiddenlinesareusedtoindicateorshowhiddenfeaturesapart.Thehiddenlineis

madeupofaseriesofdashes(1/8in.)withspaces(1/16in.)betweenthedashes.DimensionLine

- Dimensionlinesandgenerallyterminate(end)witharrowheadattheends.They’re

usuallyplacedbetweentwoextensionlines.Abreakismade,usuallyinthecenter,toplacethedimension.Thedimensionlineisplacedfrom¼in.to½in.awayfromthedrawing.Itisafinelineandisdrawnusingapencilsharpenedtoalongpoint.

ExtensionLine

- Extensionlinesarethesameweightasdimensionlines.Theselinesindicatepoints

fromwhichthedimensionaregiven.Theextensionlinebegins1/16in.awayfromtheviewandextends1/8in.passthedimensionline

Centerline

- Centerlinesaremadeupofalternatelong(3/4in.to1½in.)andshort(1/8in.)

dasheswith1/16in.spacesbetween.Thesearedrawnaboutthesameweightasdimensionandextensionlinesandareusedtolocatecentersofsymmetricalobjects.

Cutting-PlaneLine

- indicateswhereanobjecthasbeencuttoshowinteriorfeatures.Twotypesare

used:¼in.dasheswith1/16in.spacing;alongdash(3/4in.to1½in.)thentwoshortdashes(1/8in.)with1/16in.spacing.Drawthecutting-planelineslightlyheavierthananobjectline,usingapencilwitharoundedpoint.

SectionLine

- Usedwhendrawinginsidefeaturesofanobjecttoindicatethesurfacesexposedby

thecutting-planeline.Sectionlinesarealsousedtoindicategeneralclassificationsofmaterials.Theselines,lightinweight,aredrawnwithapencilsharpenedtoalongpoint.

PhantomLine

- Phantomlinesareusedtoshowalternatingpositionsofamovingpart,repeated

details,orthepathofmotionofanobject.Thelineweightisthesameascentrelines.Aphantomlineconsistsofdashes¾in.to1½in.long,separatedbyasetoftwoshort(1/8in.)dashes.

Nowthatyouknowallthedifferenttypesoflinesthatcanbeusedforsketching–labelthediagrambelowwiththecorrespondinglineabove.