3D Modeling - Cabarrus County Schools



3D Modeling002.Demonstrate 3D modeling techniques002.01Explain techniques for creating 3D geometry002.02Explain techniques for modifying and duplicating 3D geometry002.03Construct a 3D modelUNIT B: 3D ModelingCompetency: D402.00Demonstrate 3D solid modeling techniques.Objective: D402.01Explain techniques for creating 3D geometry.Introduction: The purpose of this unit is to build on the 3D CAD concepts and commands that were learned in Drafting I. When covering the 3D CAD material, it is recommended that one of the following constraint-based CAD programs be used: Inventor?, ProDesktop?, SolidWorks?, or SolidEdge?. Although it is possible to use AutoCAD? (not AutoCAD? LT) for most of the concepts, engineering firms that do serious 3D part modeling are using constraint-based or parametric modelers.Basic methods for creating geometryExtruding a profile1.Select a construction plane.2.Create a 2D profile on the selected construction plane.3.Specify the direction of the extrude.4.Specify the distance of the extrude.5.Specify the taper angle. Figure 1. Extruding a Profile.Revolving a profile1.Select a construction plane.2.Create a 2D profile on the selected construction plane.3.Create or select an axis to rotate the profile about (axis must be in the same plane as the 2D profile).4.Specify the direction of the revolve.5.Specify the angle of the revolve. Figure 2. Revolving a Profile.Making linear cuts to remove material1.Select a construction plane.2.Create a 2D profile on the selected construction plane.3.Specify the direction of cut.4.Specify the distance of the cut (through the whole object or to a specified depth). Figure 3. Making Cuts in Existing Parts.Making revolved cuts to remove material1.Select a construction plane.2.Create a 2D profile with a centerline on the selected construction plane.3.Specify the direction of cut.4.Specify the angle of revolution.Figure 4. Making Revolved Cuts in Existing Parts.Advanced Feature Creation CommandsCreating New Construction Planes or Workplanes - Most objects that require more than just simple extrudes or revolves usually require construction planes other than the 3 default planes within the software. Typical methods for constructing new planes include:Offset a new construction plane from an existing surface or plane.Creating a new construction plane parallel to an existing surface or plane through a point.Creating a new construction plane at an angle to an existing surface or plane.Offset at a DistanceOffset Through a PointAt an Angle to a PlaneFigure 5. Creating a New Construction Plane or WorkplaneLofting - Lofting is a 3D modeling technique where the user creates at least two, 2D profiles on separate construction planes and the software interpolates the solid geometry between the two profiles. Most constraint-based software allows the user to add or remove material with a loft.1.Create construction planes for each 2D profile. 2.Construct the 2D geometry on each profile.3.Activate the loft command and select each profile.4.Identify any guide curves or rails used to help the computer with the interpolation between the profiles.Figure 5. Lofted Objects.Sweeps - Sweeps are typically defined by a profile and a path. The profile determines the cross-section of the sweep and the path defines the direction of the sweep. As with the loft, most constraint-based software allows the user to add or remove material with a sweep.1.Create a sketch to define the path of the sweep.2.Create a sketch to define the profile of the sweep. Make sure the profile and the path intersect.3.Activate the sweep command and select the profile and the path.Figure 6. Swept Objects.UNIT B: 3D ModelingCompetency: D402.00Demonstrate 3D solid modeling techniques.Objective: D402.02Explain techniques for modifying and duplicating 3D geometry.Shell – The shell command is used to “hollow out” solids.1.Select the faces of the solid that will be eliminated. 2.Determine a wall thickness for the shell.Figure 1. Object Created with a Shell.Helix or Coils – A helix or coil can be used to create several types of parts. When combined with a sweep, it is especially good for creating springs and for cutting threads. Most software will allow a helix or coil to be defined by the following parameters:1.Pitch and revolution.2.Height and revolution.3.Height and pitch (good when used to produce threads).Figure 2. Objects Created with a Helix or Coil.Fillets (most CAD software does not distinguish between fillets and rounds)1.Select the edges to be filleted.2.Specify a radius of the fillet.Figure 3. Creating Fillets.Chamfers1.Select the edges to be chamfered.2.Specify the distance and angle of the chamfer. Figure 4. Creating Chamfers.Duplicating Geometry or FeaturesPatterns or Arrays - These can be created at the 2D or 3D level.Linear or Rectangular Patterns or Arraysa.Select the 2D or 3D feature(s).b.Specify a direction for copying the objects in one direction.c.Specify the distance between features as well as the number of features to duplicate in that direction.d.Specify a direction for copying the objects in another direction.c.Specify the distance between features as well as the number of features to duplicate in the second direction.Figure 5. Linear Patterns.Circular or Polar Patterns or Arraysa.Select the 2D or 3D feature(s).b.Specify an axis of rotation for the feature(s).c.Specify a direction for copying the objects.d.Specify the angle between features as well as the number of features to duplicate. Figure 6. Circular Patterns.Mirroring 3D Featuresa.Select the 3D feature(s).b.Specify a 2D plane to mirror the features about.Figure 7. Mirroring 3D Features. ................
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