DrawingObjects
Description
Inthis activity theteacher will demonstratetheuse of drafting equipmenttocreatebasicobjectshapes. Students willuseapieceof paper with atitle block to completethis activity. Studentswill practise lettering andline-weight techniques.
LessonObjectives
The student willbeableto:
•Completea boardset-up
•Identify andappropriately usedraftingtools
•Differentiateline weights
•Refineletteringtechniques
•Create basicobject shapes, based on instructions
Assumptions
The student will:
•Havea basic knowledge of draftingtoolsand equipment
•Haveafoundational understandingofhowto appropriately use drafting equipment
•Knowhowto createa titleblockon whichto completethis activity
Terminology
Borderlines:thick,darklinesusedtocreateasolidborderaroundablankpage.
Draftingboard:aflat,smoothsurfaceusuallycoveredin vinyl towhichpaperisaffixed.Thedraftingboardhassquare, paralleledgesthatallowa T-square toslideeasily.
Draftingbrush:usedtosweep away debrisfromadrawingsothefulldrawingisnotsmeared.
Erasershield:amicro-thinpieceofmetalwithcut-outsthatallowtheusertoerasedetailedsectionsofadrawingwithouterasingtherestofthedrawing.
Guidelines:thin,lightlinesdrawnusingtheletteringguideforevenlyspacedletters.
Layoutlines:verylightlinesusedtolayout measurementsbeforethosemeasurementsaredrawninheavy,darklines(borderlines).
Letteringguide:usedtoassistinthedrawingofuniformlinestodrawconsistent,evenlyspacedlettering.
Lineweight:thethicknessanddarknessofdrawnlines.
Maskingtape(draftingdots):holdsdrawingpaperand/orvellumtothedraftingboardsothepaperdoesnotshiftwhiledrawing.
Thisworkis licensedunder aCreativeCommonsAttribution-NonCommercial-ShareAlike4.0InternationalLicenseunlessotherwiseindicated.
Pencil:adrawing utensilwithamechanicalorsolidcore (lead).Leadsrangefromhardtosoft:6H,4H,2H,H,HB,2B,4B,6B.HisveryhardwithafinepointandBisextremelysoftwithabluntpoint.Ahardnessof2Hisrecommendedfortheseactivities.
Precisiondrawing:theactofcreatingdrawingswithspecializedtoolsandequipment.
Steelrule:astraightedgemadeofrigidmaterialanddivided intospecificincrements,foundbothinmetricandimperialunits.
Titleblock:comprisedoftheinformationboxes foundonthebottomright-handcornerofadrawing,thetitleblockindicatesdrawingdetailssuchasthetitle,authorname, scale,anddate adrawingwascreated.
Triangles(rightangleandisosceles):draftingguidesmadeofhard,clearplasticthatareusedtodrawlinesatverticalandsetangles(45°–90°–45°,30°–60°–90°).
T-square:aprecisiondrawinginstrumentthatisusedasaguidewithotherdraftingequipment.TheT-squarehasa90°anglewheretheheadandbladeattach.
EstimatedTime
30–60minutes
RecommendedNumberofStudents
20, basedonBCTechnologyEducators’Best PracticeGuide
Facilities
•Regularclassroom spacewith desks/chairsfor allstudents
•Drafting boards(anylargeenoughsmooth,flat surface willalsowork)
Tools
•T-square
•Steelrule
•Triangles(rightangle andisosceles)
•Eraser shield
•Draftingbrush
•Maskingtape(drafting dots)
•Draftingboard
•Letteringguide
•French curve/spline
•Circletemplate
•Compass
•2H mechanical pencil
Materials
•Handout for students with instructions (suggestion:developahandout using theinstructionsfrom the teacher-led activity).
Resources
•DraftingDictionaryActivityPlan
Teacher-ledActivity
1.Gatherallmaterials listed above.
2.Usingthe T-square andmasking tape and/or draftingdots,alignblankpaper to yourdraftingboardand securely tapedown (Figure1).
Figure1—Securepapertoboard
3.Usingthe steel rule, divide the drawingspace ofyour paperinto four even sections(eachsectionshould be 3¾"wide by4¼"high).Drawthese lines lightly(layoutlines).
4.Inthetop left section, draw anobjectthat focusses on slopingandparallellines. Practiseusingthe right angle, isoscelestriangle, and T-square.Leave enoughroom underneath theobjectforthefollowinglabel: OBJECTNo. 1PARALLELLINES ANDSLOPING LINES(Figure2).
Figure2—Parallellines and slopinglines
5.Inthetop right section, studentswill draw an object that focusses oncircular lines. Practiseusingthecircle template and protractor.Leave enoughroom underneaththe object forthefollowinglabel: OBJECT No. 2CIRCULARLINES (Figure3).
Figure3—Circularlines
6.Inthebottom left section, studentswill draw an object that focusses onlines atright angles.Practiseusing therightangleand isosceles triangles.Leaveenough room underneath theobjectforthefollowinglabel: OBJECT No. 3LINES ATRIGHT ANGLES (Figure4).
Figure4—Linesatrightangles
7.Inthebottom right section studentswill draw an object that focusses onfree-form lines.Practiseusingthe French curveand/or spline too.Leaveenough room underneaththe objectforthefollowinglabel: OBJECT No. 4FREE FORMWITHFRENCHCURVE (Figure5).
Figure5—Freeformwith Frenchcurve
8.Fill inthetitle block at the bottom of the pagewiththeinformation below.Remind studentsthatdraftingconventionrequires that allletteringbedoneinCAPITALS.
ACTIVITY#1 / NAMEDATE
OBJECTS / SCALEOFDRAWING1:1
PAGE1OF1
StudentActivity
•Complete object shapedrawings.
•Fill intitleblock withappropriateinformation.
ExtensionActivity
•Practisedrawingmoreobjects, usingallthetools inthe DraftingDictionaryActivityPlan.
•Practiseletteringwhenlabellingobject drawings.
Assessment
•Studentparticipationindiscussion/demonstration
•Criteria forcompleted drawing:
–Basic object shapesare drawnbased on instructions.
–Corners ofbordersareclosed (horizontal and verticallinescross).
–Lettering is neat,even, and alluppercase.
–Title block isfilledout correctly withappropriateinformation.
AppendixAcknowledgment
© Camosun College.TradesAccess Common Core:CompetencyD-3:ReadDrawingsandSpecifications(pp. 25–33). The Trades AccessCommonCoreresourcesare licensedunderthe Creative Commons Attribution 4.0 Unported Licence( otherwise noted.
Describelines,lettering,and dimensioning indrawings
Thepurposeofengineeringdrawingsistoconveyobjectivefacts,whereasartisticdrawingsconveyemotionorartisticsensitivityinsomeway.
Engineeringdrawingsandsketchesneedtodisplaysimplicityanduniformity,andtheymustbeexecutedwithspeed.Engineeringdrawinghasevolvedintoalanguagethatusesanextensivesetofconventionstoconveyinformationveryprecisely,withverylittleambiguity.
Standardizationisalsoveryimportant,asitaidsinternationalization;thatis,peoplefromdifferentcountrieswhospeakdifferentlanguagescanreadthesameengineeringdrawingandinterpretitthesameway.Tothatend,drawingsshouldbeasfreeofnotesandabbreviationsaspossiblesothatthemeaningisconveyedgraphically.
Line styles and types
Standardlineshavebeendevelopedsothateverydrawingorsketchconveysthesamemeaningtoeveryone.Inordertoconveythatmeaning,thelinesusedintechnicaldrawingshavebothadefi epatternandadefi ethickness.Somelinesarecompleteandothersarebroken.Somelinesarethickandothersarethin.Avisibleline,forexample,isusedtoshowtheedges(or“outline”)ofanobjectandtomakeitstandoutforeasyreading.Thislineismadethickanddark.Ontheotherhand,acentreline,whichlocatestheprecisecentreofaholeorshaft,isdrawnthinandmadewithlongandshortdashes.Thismakesiteasilydistinguishablefromthevisibleline.
Whenyoudraw,useafairlysharppencilofthecorrectgradeandtrytomaintainaneven,consistentpressuretomakeiteasierforyoutoproduceacceptablelines(Figure1).Studythelinethicknesses(or“lineweights”)showninFigure2andpractisemakingthem.
TechnicalSketching
9H 8H 7H 6H 5H 4H 3H 2H HFHBB2B 3B 4B 5B 6B 7B 8B 9B
HardnessBlackness
Figure1—Leadgradeandusage
Incomputerdrafting,thelineshaperemainsthesame,butlinethicknessmaynotvaryasitdoesinmanuallycreateddrawings.Somelines,suchascentrelines,maynotcrossinthesamemannerasinamanualdrawing.Formostcomputerdrafting,linethicknessisnotimportant.
Type / Weight / Line / DescriptionObjectlineMarginline / Heavy / Solidlinetoshowvisibleshape,edges,andoutlines.
Hiddenbodyline / Medium / Brokenlineoflongandshortdashestoshowhiddenobjectlinesnotvisibletotheeye.
Phantomline / Light / Brokenlineofshortdashestoshowalternatepositionsormovementofapart.
Sectionline / Light /
SteelCopper/Brass
LeadCastiron/Generalpurpose / Unbrokenlinesarrangedinapattern,usuallystraightandata45ºdiagonal.
Projectionline / Light / Unbrokenlinesthatextendawayfromtheobjectorfeatureforemphasis.
Centreline / Light / Brokenlineoflongandshortdashestoshowthecentreofanobject.
Extensionline/Dimensionline / Light / 25mm / Extensionlinesaresmalllinesthatextendoutwardfromanobjectorfeature.Dimensionlinesspanbetweentheextensionlineswitharrowheadsandagivendimension.
Leaderline / Light / Label / Unbrokenlineusuallydrawnatanangleoftenwitha“dogleg”andanarrowhead.Adotisusedinplaceofanarrowheadwhereasurfaceisreferenced.
Usuallyaccompaniedbyalabel.
Cuttingplaneline / Heavy / AA / Brokenlineofonelongandtwoshortdashestoshowanimaginarycross-section.Thearrowheadsshowthedirectionfromwherethecross-sectionisviewed.AcorrespondingimagewillshowtheviewofA.
Breaklinesforwoodandmetal / Heavy / Unbrokenfreehandorstraightzig-zaglinestoabbre-viatelongerspansofwoodormetal.
Breaklinesforpiping / Heavy / Curledlinestoabbreviatealongerspanofpipe.
Figure2—Weightsoflines
8“Download for free at
Youth Explore TradesSkills
Toproperlyreadandinterpretdrawings,youmustknowthemeaningofeachlineandunderstandhoweachisusedtoconstructadrawing.Thetenmostcommonareoftenreferredtoasthe“alphabetoflines.”Let’slookatanexplanationandexampleofeachtype.
Objectlines
Objectlines(Figure3)arethemostcommonlinesusedindrawings.Thesethick,solidlinesshowthevisibleedges,corners,andsurfacesofapart.Objectlinesstandoutonthedrawingandclearlydefi theoutlineandfeaturesoftheobject.
Figure3—Objectlines
Hiddenlines
Hiddenlines(Figure4)areusedtoshowedgesandsurfacesthatarenotvisibleinaview.Theselinesaredrawnasthin,evenlyspaceddashes.Asurfaceoredgethatisshowninoneviewwithanobjectlinewillbeshowninanotherviewwithahiddenline.
Figure4—Hiddenlines
Centrelines
Centrelines(Figure5)areusedindrawingsforseveraldifferentapplications.Themeaningofacentrelineisnormallydeterminedbyhowitisused.Centrelinesarethin,alternatinglong
andshortdashesthataregenerallyusedtoshowholecentresandcentrepositionsofroundedfeatures,suchasarcsandradii.Arcsaresectionsofacircle,andradiiareroundedcornersoredgesofapart.Centrelinescanalsoshowthesymmetryofanobject.
Figure5—Centrelines
Dimensionandextensionlines
Dimensionandextensionlines(Figure6)arethin,solidlinesthatshowthedirection,length,andlimitsofthedimensionsofapart.Dimensionlinesaredrawnwithanarrowheadatbothends.
Extensionlinesaredrawncloseto,butnevertouching,theedgesorsurfacetheylimit.Theyshouldbeperpendicular,oratrightangles,tothedimensionline.Thelengthofextensionlinesisgenerallysuitedtothenumberofdimensionstheylimit.
DimensionlineExtensionline
Dimension
Endmarks
62
Objectline
Figure6—Dimensionandextensionlines
Leaderlines
Leaderlines(Figure7)showinformationsuchasdimensionalnotes,materialspecifications,andprocessnotes.Theselinesarenormallydrawnasthin,solidlineswithanarrowheadatoneend.Theyarebentorangledatthestart,butshouldalwaysendhorizontalatthenotation.Whenleaderlinesreferenceasurface,adotisusedinsteadofanarrowhead.
Leaderline(thinandsolid)
Flatbar3mmthickR20
ø8 2holes
Copperplatethissurface
Figure7—Leaderlines
Notethatthesymboløisusedtoindicateadiameterratherthantheabbreviation“DIA.”Thenumberthatimmediatelyfollowsthissymbolisthediameterofthehole,followedbythenumberofholesthatmustbedrilledtothatdimension.
Phantomlines
Likecentrelines,phantomlines(Figure8)areusedforseveralpurposesinblueprints.Phantomlinesareusedtoshowalternatepositionsformovingpartsandthepositionsofrelatedoradjacentparts,andtoeliminaterepeateddetails.Phantomlinesaredrawnasthin,alternatinglongdashesseparatedbytwoshortdashes.
Existingcolumn
Figure8—Phantomlines
Cuttingplanelines
Cuttingplanelines(Figure9)showthelocationandpathofimaginarycutsmadethroughpartstoshowinternaldetails.Inmostcases,sectionalviews(orviewsthatshowcomplicatedinternaldetailsofapart)areindicatedbyusingacuttingplaneline.Theselinesarethick,alternatinglonglinesseparatedbytwoshortdashes.Thearrowheadsateachendshowtheviewingdirectionoftherelatedsectionalview.Thetwomaintypesofcuttingplanelinesarethestraightandtheoffset.
Cuttingplaneline(thickwithonelongthentwoshortdashes)
AABB
SectionA–ASectionB–B
Figure9—Cuttingplanelines
Sectionlines
Sectionlines,alsoknownassectionallining,(Figure10)indicatethesurfacesinasectionalviewastheywouldappearifthepartwereactuallycutalongthecuttingplaneline.Theseare solidlinesthatarenormallydrawnat45degreeangles.Differentsymbolsareusedtorepresentdifferenttypesofmaterials.
Sectionlines(thinandsolid)
SectionB–B
Figure10—Sectionlinescombinedwithcuttingplanelines
Breaklines
Breaklinesaredrawntoshowthataparthasbeenshortenedtoreduceitssizeonthedrawing.Thetwovariationsofbreaklinescommontoblueprintsarethelongbreaklineandtheshortbreakline(Figure11).Longbreaklinesarethinsolidlinesthathavezigzagstoindicateabreak.Shortbreaklinesarethick,wavysolidlinesthataredrawnfreehand.Wheneitherofthesebreaklinesisusedtoshortenanobject,youcanassumethatthesectionremovedfromthepartisidenticaltotheportionsshownoneithersideofthebreak.
Figure11—Breakline
Standardlettering
Thelettersandnumbersonadrawingorsketchareasimportantasthelines.Scribbled,smudged,orbadlywrittenlettersandnumberscanbecomeimpossibletoread.Thismayleadtotime-consumingandcostlyerrors.Letteringisnecessarytodescribe:
•thenameortitleofadrawing
•whenitwasmade
•thescale
•whosketchedit
•thedimensions
•thespecialnotationsthatdescribethesize
•thematerialstobeused
•theconstructionmethods
TheAmericanStandardVerticalletters(Figure12)havebecomethemostacceptedstyleofletteringusedintheproductionofmanualdrafting.ThisletteringisaGothicsansserifscript,formedbyaseriesofshortstrokes.
Fontstylesandsizesmayvaryincomputerdrafting.Notethatalllettersarewrittenascapital(uppercase)letters.Practisethesecharacters,concentratingonformingthecorrectshape.
Rememberthatlettersandnumbersmustbeblacksothattheywillstandoutandbeeasytoread.Letteringandfiguresshouldhavethesameweightanddarknessashiddenlines.
Titleanddrawingsizes=6mm(¼")
ABCDEFGHIJKL MNO P Q R ST UVW X Y Z 0 1 2 3 4 5 6 7 8 9
Dimension andnotationsizes =3mm (1⁄s")A B C D E F G H I J K LM N O P Q R S T U V W
XYZ0123456789
Figure12—Standardlettering
Abbreviations
Abbreviationsarecommonlyusedtohelpsimplifyadrawingandconservespace.Althoughmanyfieldssharecommonabbreviationconventions,therearealsofield-ortrades-specificconventionsthatyouwillseeasyoubecomemorespecialized.Hereisacommonlistofabbreviationsthatareusedondrawings.Eachtradewillhavespecificabbreviationsfromthislist,andthereforeasetofdrawingswillusuallyincludeanabbreviationkey.
ABanchorbolt
ABTaboutAUXauxiliaryBCboltcircle
BBEbevelbothendsBCDboltcirclediameterBOEbeveloneend
BEbothends
BLbaseline
BMbenchmark
Btmbottom
BPbaseplate
B/Pblueprint
BLDblind
C/CcentretocentreCOLcolumn
CPLG coupling
CScarbonsteelC/WcompletewithCYLcylinder
DIAdiameterDIAG diagonalDIMdimensionDWG drawingEAeach
ELelevation
EXTexternal
F/Ffacetoface
FFflatface
FLGflange
FWfilletweld
GagaugeGalvgalvanizedHVYheavy
HHhexhead
HRhotrolled
HTheattreatment
HLSholes
HSShollowstructuralsteelIDinsidediameter
INinches
INTinternal
ISOInternationalStandardsOrg.KPkickplate
LHlefthand
LATlateral
LRlongradius
LGlong
MBmachineboltMSmildsteelMINminimumMAXmaximumMAT’L material
MISC miscellaneousNCnationalcourseNFnationalfine
NOnumberMOM nominalNTSnottoscale
NPSnominalpipesizeNPTnationalpipethreadO/Concentre
OAoverall
ODoutsidediameterORoutsideradiusOPPopposite
PATpattern
PBEplainbothendsPOEplainoneend
PSIpoundspersquareinchPROJ project
RDrunning dimensionRorRadradius
RNDround
REFreferenceREQ’D requiredREVrevision
RFraisedface
RHrighthandSCHschedule
SIInternationalSystemofUnitsSPECS specifications
SQsquare
SMseamSMLS seamless
S/SseamtoseamSOslipon
SECsection
STDstandard
SSstainlesssteelSYMsymmetrical Ttop
T&Btopandbottom
T&CthreadedandcoupledTHDthreaded
TBEthreadedbothendsTOEthreadedoneendTHKthick
TOLtolerance
TOCtopofconcreteTOStopofsteelTYPtypical
U/NunlessnotedVERT vertical
WDworkingdrawingWPworkingpoint
WTweightW/Owithout
XHextraheavy
XSextrastrong