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Engineering H191 Engineering Fundamentals and Laboratory I

Engineering H191 Engineering Fundamentals and Laboratory I. Lecture 12 Constructive Solid Geometry and Missing Lines. Objectives. 3D Solid models Primitive Constraint based Feature based 2D Layout drawings Missing Line Orthographic Drawings 3 Surface types

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Engineering H191 Engineering Fundamentals and Laboratory I

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  1. Engineering H191Engineering Fundamentals and Laboratory I Lecture 12 Constructive Solid Geometry and Missing Lines

  2. Objectives • 3D Solid models • Primitive • Constraint based • Feature based • 2D Layout drawings • Missing Line Orthographic Drawings • 3 Surface types • Procedure for producing isometric Autumn 2008

  3. Review of Important Concepts in CAD • CAD model is a "virtual" part • A 3D CAD model stores the entire 3D shape of the object • 3D models can be generated from 2D profiles by using CAD programs Autumn 2008

  4. Approaches to Developing a Solid Model • Constructive solid or primitive modeling • Constraint-based modeling • Feature-based modeling Autumn 2008

  5. Primitive Modeling – Combine Simple Shapes Autumn 2008

  6. Constraint-based Solids Modeling • Part "roughed" in, often by "sketching" • Constrained or detailed by adding dimensions • 3D Objects created by revolving or extruding Autumn 2008

  7. Constraint-based Solids Modeling: Extruding Create 2D Shape Extrude 2D Shape Autumn 2008

  8. Constraint-based Solids Modeling: Revolving Revolve the Shape Draw 2D Shape Autumn 2008

  9. Feature-based Modeling • Feature-based modeling involves creating and modifying geometric features of a solid model like a manufacturing process. • Let's consider how an engineer would model a part and compare it to how a machinist might fabricate the part in the following example… Autumn 2008

  10. Feature-based Process

  11. How Solid Models Can Be Used • Improve efficiency in design by visualization and virtual assembly • Link to Numerical computational techniques for • Stress Analysis • Heat Transfer Analysis • Fluid Flow Dynamics • Link to Computer-aided Manufacturing Autumn 2008

  12. Autodesk Inventor • Basic models are initially built from primitive shapes by extrusion or rotation and then are modified to create more complex objects • Think of it as "electronic" modeling clay Autumn 2008

  13. Creating Layout Mode drawings • Even if the model is built with a 3D construction approach, conventional orthographic views with dimensioning and in some cases sectioning will be needed. • Later this quarter, we'll use Inventor to create layout mode drawings, starting with a 3D model. • Procedures and conventions for proper dimensioning will be covered later Autumn 2008

  14. Creating Layout Mode drawings • Inventor has two system modes: • Model mode (3D) • Layout mode (2D) • Inventor distinguishes between the two so that you can create part files in Model mode, then switch to Layout mode to create different layouts of the part file and detail them for drafting purposes. Autumn 2008

  15. Creating Layout Mode drawings • In Model mode you can take advantage of all the Inventor functions to create and edit part files. • Model mode is the default system mode that you enter when you start Inventor. • Layout mode is a drafting tool that you use to create, dimension, and then print or plot Autumn 2008

  16. Review Questions • What are the three types of solid modeling that we have discussed? • Primitive, Constraint based, Feature based • What are the two modes that are used in Inventor? • Model Mode and Layout Mode Autumn 2008

  17. Missing Line Problems • Three surface types • Principal • Inclined • Oblique • General Procedure • Example Autumn 2008

  18. Miter Line 1 2 4 3 A 4,1 3,2 2,1 3,4 Surface Type A: Principal Surface • True size in one view • Edge (line) in other 2 views • Plane  Line Autumn 2008

  19. 1 2 4 3 B 4,1 1 4 2 3,2 3 Surface Type B: Inclined Surface • Characteristic shape in 2 views but not true size in either • Edge (line) in 3rd view • Lengths of sides can be determined from appropriate views Autumn 2008

  20. 2 Q: In which views could you get the true length of edges of this oblique surface? 1 to 2 1 to 3 3 to 2 1 3 C 2 1 1 2 3 3 Surface Type C: Oblique Surface • Characteristic shape in all 3 views but true size in none Autumn 2008

  21. Missing Line Problem • Given 3 principal views with 1 or more views being incomplete • Sketch the isometric pictorial and complete the partial view(s) Autumn 2008

  22. General Procedure • Step 1 – Sketch the box for isometric view • Step 2 – Choose a surface and identify its type • Step 3 – Map surface to the pictorial • Step 4 – Repeat for all surfaces • Step 5 – Compare pictorial to ALL orthographic views • Step 6 – Complete the orthographic views by adding missing line(s) Autumn 2008

  23. The Orthographic Views Sketch Autumn 2008

  24. The Isometric Grid Autumn 2008

  25. Box Object Autumn 2008

  26. A Choose and Map a Surface • Identify the Principal Surface A Autumn 2008

  27. B Map Another Surface • Identify the Inclined Surface B Autumn 2008

  28. C Map Surface • Identify Principal Surface C Autumn 2008

  29. D Map Surface • Identify Oblique Surface D Autumn 2008

  30. Map Surface • Identify Principal Surface Autumn 2008

  31. Map Surface • Identify Principal Surface Autumn 2008

  32. Map Surface • Identify Principal Surface Autumn 2008

  33. Notch Q: What kind of surface has its characteristic shape in 2 views? This surface would show up as an edge in the 3rd view Inclined Surface  Autumn 2008

  34. Finished Example Autumn 2008

  35. A B C Review: Surface Types Inclined Surface B Principal SurfaceA Oblique Surface C Autumn 2008

  36. Recall the Six Principal Views Autumn 2008

  37. Summary • Principal, Inclined and Oblique surfaces were defined • How to identify these surfaces • General procedure for solving missing line problems Autumn 2008

  38. Reminder: Tips for Your Computer Account DO save your files to your “network” drive (Drive letter N:). DO remember to log off the computer when your are finished. DO backup your files on: USB drive CD-R or DVD (where available) Your own computer via Remote Desktop Do remember to take your USB drive with you. Autumn 2008

  39. Reminder: Tips for Your Computer Account DO NOT store any files into the "Profile" folder in your personal directory. The "Profile" folder size limit is relatively small (~60 Mbytes). The “Profile” is re-written when you log off and you will lose data. DO NOT store any files on the "Desktop". Doing so uses "Profile" space. DO NOT store any files in the " My Documents" folder. Doing so usually uses "Profile" space. DO NOT forget your USB drive. Autumn 2008 39

  40. Remote Desktop Connection Application To access your network drive from your own computer, start the Windows “Remote Desktop Connection” (RDC) application which will be found in the “Accessories” Program folder. Before making a connection, be sure your local drives are selected so that they will be available while the Terminal Server session is active. In RDC, click Options, click Local Resources tab, and then click More button. Put a check in “Drives” checkbox. Autumn 2008

  41. Remote Desktop Connection Application Remote access is available through the Terminal Server running on the Engineering Region 1 “Liberty” host computer. Use Windows “Remote Desktop Connection” (RDC) to connect to one of the following “hosts”: 164.107.37.181 164.107.37.182 164.107.37.183 Autumn 2008

  42. Remote Desktop Connection Application After the connection is established, just use the same logon credentials as you use in the Hitchcock Hall classrooms. You may now simply copy files between your directory on Terminal Server and your directory on your local drive. Note that Inventor 2008 will not run in a RDC session. Autumn 2008

  43. Today's Assignment • Drawing 13 • Inventor Chapter 3 – Exercise 2 • Drawing 14 • Missing Lines – ML-2 • Complete orthographic views and draw corresponding isometrics Autumn 2008

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