Create a 2D Sketch Using Constraints and Dimensions

3DModellingaSetofStairs

Description

Inthis activitystudentswill beginbydrawing a setof stairsin 2Dsimilarto theone drawnpreviously using theisometricview. Then they will extrudethe drawingto createathree-dimensionalrendering.The intentof this activity istolearn howto draw a2D sketch usingthedrawingtoolsandhow the constraints and dimensionstools affect howand whatyou draw.

Drawingmethodswillvary slightlyineach software package,butthe overallconcepts are thesame. As this activity does not necessarilyhaveto followthe previous CADactivities underMechanical CAD, the studentmayhaveless knowledgeof the terminology, the drawingtoolsandhow touse them.

LessonObjectives

The student willbeableto:

•Create a 2D sketch using constraints and dimensions

•Usevarioustools to edit the 2D sketch

•Extrudea2D sketch

Assumptions

The student will:

•Knowhow tologin toa computer and openup thesoftware

•Understandtheworking environment ofthesoftware andhow to navigate it

•Havealreadycreateda simple 2D sketch inthe software(tobe repeated as partof thisactivity)

Terminology

Note: terms withan asterisk (*) are copyright theAutodesk Knowledge Network, licensedunderaCreative Commons Attribution-NonCommercial-ShareAlike3.0Licence(CCBYNCSA 3.0)

Applicationbutton:theiconinthetopleftcornerofthescreenthatcontainsNew,Open,Save,etc.

Assemblyconstraints*:rulesthatdeterminehowpartsinanassemblyareplacedrelative tootherpartsinthe assembly.Constraintsremovedegreesoffreedom.Assemblyconstraints

include angle, flush, mate, andtangent.Constraints may beplacedbetweenfacesof features,partedges,points,inferredaxes,andpartworkfeaturessuchasplanes,axes,andpoints.

Thisworkis licensedunder aCreativeCommonsAttribution-NonCommercial-ShareAlike4.0InternationalLicenseunlessotherwiseindicated.

Assemblymodelling*:twoormorecomponents(partsorsubassemblies)consideredasasinglemodel.Anassemblytypicallyincludesmultiplecomponentspositioned absolutelyandrelatively(as required) withconstraintsthatdefineboth size andposition.Assemblycomponentsmay includefeaturesdefinedinplaceintheassembly.Massandmaterialproperties may beinheritedfromindividualpartfiles.

Browser*:sometimescalledthemodeltree, isthegraphicalhierarchyshowingrelationshipsbetweengeometricelementsinparts,assemblies,anddrawings.Iconsrepresent sketches,features,constraints,orattributesforeachmodel.Objectsareshowninthebrowserintheorderinwhichthey werecreated. Objectsmayalsobeedited,renamed,added,deleted, copied,andmovedtoadifferentlocationinthe browser.

Constraints*:rulesthatgoverntheposition,slope,tangency, dimensions,andrelationshipsamongsketchgeometryorthe relativepositionbetweenpartsinanassembly.Geometricconstraintscontroltheshapesandrelationshipsamong sketchelementsorassemblycomponents.Dimensionalconstraintscontrol size. Applyingconstraints removes degreesoffreedom.

Drawing:a2Drepresentationofapartorassembly.Thedrawingfiletypehasan.idwextension.

Extrude*:a feature created by addingdepthtoa sketched profile.Feature shapeiscontrolled byprofileshape,extrusionextent,andtaper angle.

Fullyconstrained:whena2Dsketchor3Dparthashadallthedegreesoffreedomremovedanditcannotbefreelymoved anymore.

Graphicswindow*:theactivemodellingareainwhichsketches,constraints,features,parts,andassembliesarecreatedand edited. IntheGraphics window, modelscanbe rotated, zoomedinandout,andviewcharacteristicssuchas colour, material,andlightdefined.

Hardsnap:snapfunctionrepresentedbyagreendotthatappearswhensnappingtotheendpointofasketch line.Ahardsnapispermanentandcannotbe moved.

Homeview:anisometricviewofyourmodel.WhentheHomebuttonontheViewCubeispressed,itzoomsinandre-orientsthemodelintheisometricviewintheGraphicswindow.

Markingmenu:whenyourightmouseclickintheGraphicswindowinvariousmodes(sketch,3D model) amenucomesupwithenvironment-specificcommandoptionsarrangedinaradial,ratherthanlinear,display.

Navigationbar:atoolbarcontainingvarioustoolstomove orviewyour 2Dsketch or3DpartintheGraphics window.

Origin:thepointwherethex,y,andzplanesoraxesintersect.

Part:agroupof features andfacesthat havebeencombinedtocreateaclosed volumethatisrepresentedasa3Dobject.

Partmodellingenvironment*:theenvironmentwhereyoucreatesketchesandbyusingdifferentcommandseventually createa3Dpart.Inpartmodelling,you createsketches, usefeaturecommandstocreatethree-dimensionalfeatures,andthencombinethefeatures tocreateparts.

Ribbon:thepalettethatextendsacrossthetopoftheInventorinterfaceandcontainsmultipletabsforconvenienttoolaccess.

Shell*:aparametricfeature usedmostfrequentlyforcastormouldedparts. From aspecifiedface,materialis removed fromthepart, leaving acavitywithwallsofaspecifiedthickness.Shellsusually havewallsofuniformthickness,butindividualfacescanbeselectedandtheirthicknessspecified.Shellwallscanbeoffsettothe inside, outside,orbothsidesofthepart, relative totheoriginalpartsurfaces.

Sketch*:consistsofthesketchplane, acoordinatesystem, 2Dcurves,andthedimensionsandconstraintsappliedtothecurves.Asketch mayalsoincorporateconstructiongeometryorreference geometry. Sketches areusedtodefine feature profilesandpaths.

Sketchenvironment*:consistsofasketchandsketchcommands.Thecommandscontrolthesketchgridanddrawlines,splines,circles,ellipses,arcs,rectangles,polygons,orpoints.

Sketchplane:aplanarfaceorworkplaneonwhichthecurrent sketchiscreated.

Softsnap:snapfunctionrepresentedbyayellowdotthatisnotconstrained,andthereforecanbemoved.

Statusbar*:a displayacrossthebottomoftheactivewindowthatindicatesthenextactionthattheactivecommandrequires.Whena2D sketchor3Dsketch isactive, thestatusbarfor sketchdisplays commandsspecifictothe sketch environment.

STEPfile*:aninternationalformatdevelopedtoovercomesomeofthelimitationsofcurrentdataconversionstandards.FilescreatedinotherCAD systems canbeconvertedto STEP formatandimportedintoAutodeskInventor.

ViewCube:aninterfaceontheGraphicswindowthathelpsswitchbetweenstandard(front,side,top,etc.)viewsandisometricviewsofthemodel.

Workplane:thexy(front view),xz(top view), andyz(side view)planes. Sketchesand3Dobjectsaredrawnontheseplanes.

EstimatedTime

45–60minutes

RecommendedNumberofStudents

20, basedonBCTechnologyEducators’Best PracticeGuide

Facilities

Computerlabinstalledwith 3D modelling software (AutodeskInventor,PTCCreoParametric,SolidWorks,etc.)

Tools

Projectorwithcomputerandspeakers,Internet access

Materials

Handoutfor students withinstructions

Resources

Instructionalvideofor teacherand students to follow(Inventor2013):

•11.1:Constraining and Dimensioning 2D Sketches

•11.2:Drawing YourStairs

•11.3:ExtrudingYourStairs

Teacher-ledActivity

Useacomputerwitha projector and demonstratethe following:

1.Opentheprogram and explain the environment(Browser, Ribbon, ViewCube,Navigationbar, Applicationmenu).

2.Showhow to navigate in the sketchenvironment orpartmodelling environmentusing themouse(scroll left/right, zoomin/out,pan,orbit),theViewCube,andNavigationbartools(NavigationWheel,Zoom,Pan,Orbit).

3.Startapart in imperialor metric.

4.Create a2Dsketch in the sketch environment.

5.Extrudea2Dsketch into3Din thepart modelling environment.

6.Modifya2Dsketch after it hasbeencreated inthe sketch environment.

7.Modifya3Dpart after ithasbeencreated inthe part modelling environment

StudentActivity

StudentswillfollowtheStudent Activity“Drawing3DStairs” and/or thevideotutorials tocompletetheassignment.

Assessment

Students willshowthe teacher their completedassignments.Theteacher canhave theassignment printedout orlook at it onthe computer screen.If the student does notproduceexactly whatwasshown, then an associated mark based onerrorscanbe derived.

StudentActivity:PrototypingYourModelUsing3DPrintingandCNCTechnology

Usingthe softwareto learn basic 2Dsketch skills, you are goingto drawa setofstairs and thenextrude them,renderingthemas a three-dimensional image(Figure6).

1.Opena newpartfrom theapplication menuor from the getstartedtabon theribbon(Figure1).

Figure1

2.Next create a 2D sketchandhighlightthexyplane(frontplane,Figure2).Theprogramwillnow enterinto the sketch environment.

Figure2

3.Drawthestairsasshown(Figure3).Thestepswillhave a 2" rise and a 2"run.Thetotalheightofthestairswill be 10"andthetotaldepthwill be 10"aswell.

Figure3

4.Dimensiontheentiredrawing so itisfullyconstrained(Figure4).Inthelowerright corner ofthestatusbar itwill tell you how manymore dimensions you need tofullyconstrainit.

Figure4

5.Once thesketchhasbeenfullyconstrained, click “FinishSketch” on therightsideofthesketch ribbonto exitthe sketch environment.

6.Nowselect “Extrude” from the 3Dmodel ribbonand select insidethe stairs. The stairs willextrude into3D.Inthe “Extrude” dialogbox,changethedepthofthe extrusion to10"(Figure5).ClickOKtofinishtheextrusion.

Figure5

7.Yourmodelshouldnow be completeandthestairsshould look liketheonesinFigure6.

Figure6