1. Engineering Graphics Stephen W. Crown Ph.D.
Solid Modeling
Engineering Graphics
Stephen W. Crown Ph.D.

2. Objective To learn how to generate solid models in CAD
To understand how to use solid modeling in the design process

3. Overview Primitives Extrude Sweep Revolve Blend Solid Model Operators
Viewing Solid Models

4. Solid Models
Definition: A 3-D model of an object that contains volumetric information
Mass can be represented
Interior surfaces are generated automatically as portions of an object are removed
Easily constructed using primitive shapes, extruding, and revolving

5. Solid Primitives
Box (Parallelepiped)
Cylinder
Cone
Sphere
Wedge

6. Example: Using Primitives
Box
Wedge
Union / Protrusion
6 boxes
2 wedges
Subtract / Cut
1 box - minus 2 wedges
1 box - minus 2 boxes

7. EXTRUDE
Two dimensional closed objects can be extruded to give solid objects
The direction of the extrusion is typically normal to the 2-D cross sectional sketch
The height of extrusion can be specified

8. SWEEP The path of the extrusion must be defined (trajectory)
The extruded cross section must be defined
The cross section stays normal to the path

9. REVOLVE
Two dimensional closed objects can be revolved to give solid objects
The axis of rotation must be defined
The angle of revolution must be specified

10. BLEND
Smooth transition can be made between two closed shapes with similar geometry (i.e. equal number of vertices)
The distance between sections must be defined
The angle of twist between sections must be specified

11. Solid Model Operators
Subtract / Cut
Intersection
Union / Protrusion

12. Solid Model Operators Subtract / Cut subtracts one solid from another
One solid is subtracted from the other.

13. Solid Model Operators Intersection
Creates a solid that represents the region that is in common to the selected solids

14. Solid Model Operators Union / Protrusion
Creates a single solid from two solids that intersect

15. Example: Solid Model Operators
What procedure would you follow to create the two mating parts?
Create the bounding box for the upper part
Create the two cylinders
Subtract the cylinders from the box
Create the bounding box for the lower part
Subtract the finished upper part

16. Example: Solids from Drawings
Extrude the view with the most detailed perimeter
The depth of the extrusion may be found from an adjacent view

17. Example: Solids from Drawings
Use the perimeter of other views to make additional cuts
Interpret interior details by making assumptions about geometry in one view and testing them in adjacent views

18. Example: Solids from Drawings
Verify that the completed part satisfies every view
Generate a multiview drawing from the solid part and compare to the original sketch or drawing

19. Using Solid Modeling for Design
Intersection of wedge and cylinders is not clearly defined
Construction of solid model forces resolution regarding details of construction

20. Using Solid Modeling for Design
Intersection of wedge with post produces a gap, a ledge, or a circular groove
Intersection of wedge with base produces a ledge, an overhang, or requires a rounded end
These details can be shown in the multiview drawing but are more obvious in the solid model

21. Viewing Solid Models Rendering Styles Wireframe with hidden lines
Hidden lines removed
Shaded

22. Viewing Solid Models LIGHTING SURFACE FINISH
Distance, Point, Spotlight
Ambient light
Intensity
Modify (specify location of light)
SURFACE FINISH
Specify roughness, color, sensitivity to ambient light, texture maps, and bump maps
Apply finishes to individual parts or assemblies