1. Oblique Projection Chapter 15

2. 2 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Objectives Create an oblique projection List the advantages and disadvantages of oblique projection Draw cavalier and cabinet oblique drawings

3. 3 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Objectives (cont.) Select the best view for circular shapes in an oblique drawing Describe why CAD software does not automatically create oblique drawings

4. 4 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Oblique Projections In oblique projections, the projectors are parallel to each other but are not perpendicular to the plane of projection One of the object’s principal faces is parallel to the plane of projection

5. 5 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Oblique Projections

6. 6 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Cavalier Projection When the receding lines are true length, and the projectors are at 45 degrees to the plane of projection, the oblique drawing is called cavalier projection

7. 7 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Cabinet Projection When the receding lines are drawn to half size, the drawing is known as a cabinet projection

8. 8 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Cavalier and Cabinet Projection

9. 9 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Choice of Position Important shapes should be parallel to the viewing plane

10. 10 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Ellipses for Oblique Drawings If using a CAD system, you can draw an ellipse by specifying its center and major and minor axes If sketching, you can block in the enclosing rectangle and sketch the ellipse tangent to its sides

11. 11 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Offset Measurements Circles, circular arcs, and other curved surfaces are drawn using offset measurements

12. 12 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Angles in Oblique Projection When an angle is specified in degrees in a receding plane, convert the angle into linear measurements to draw the angle in an oblique drawing

13. 13 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Angles in Oblique Projection

14. 14 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Oblique Sections Sections are useful to show interior shapes In general, all types of sections for isometric drawing may be applied to oblique drawing

15. 15 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Screw Threads in Oblique Partial circles spaced equally show symbolic thread pitch

16. 16 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Oblique Dimensioning Oblique drawings are dimensioned in a similar fashion as isometric drawings

17. 17 Technical Drawing 13 th Edition Giesecke, Mitchell, Spencer, Hill Dygdon, Novak, Lockhart © 2009 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved. Computer Graphics Using CAD, oblique drawings can be created by using snap increments and drawing similarly to drawing on grid paper If a complicated pictorial is needed however, it may be easier and more accurate to create a 3D model