1. Axonometric Projection
Chapter 14

2. Objectives
Describe the differences between multiview projection, axonometric projection, oblique projection, and perspective
Sketch examples of an isometric cube, a dimetric cube, and a trimetric cube

3. Objectives (cont.)
List the advantages of multiview projection, axonometric projection, oblique projection, and perspective
Create an isometric drawing given a multiview drawing
Use the isometric axes to locate drawing points

4. Objectives (cont.) Draw inclined and oblique surfaces in isometric
Draw angles, ellipses, and irregular curves in isometric

5. Projection Methods

6. Types of Axonometric Projection
Isometric – has equal foreshortening along each of the three axis directions
Dimetric – has equal foreshortening along two axis directions and a different amount on the third axis
Trimetric – has different foreshortening along all three axis directions

7. Types of Axonometric Projection

8. Isometric Projection
The projections of the edges of a cube in isometric projection make angles of 120 degrees with each other

9. Isometric Projection
Lines of an isometric drawing that are not parallel to the isometric axes are called nonisometric lines
These lines are not equally foreshortened

10. Isometric Projection
Isometric scales can be used to draw correct isometric projections
All distances are approximately 80% of true size

11. Isometric Drawings
Isometric drawings, unlike isometric projections, are drawn using the full length measurements of the actual drawing and lacks foreshortening
The isometric drawing is about 25% larger than the isometric projection

12. Making an Isometric Drawing

13. Isometric Drawings of Inclined Surfaces

14. Hidden Lines and Centerlines
Hidden lines are omitted unless they are needed to make the drawing clear
Center lines are shown if they are needed to indicate symmetry or if they are needed for dimensioning

15. Angles in Isometric
Angles project true size only when the plane containing the angle is parallel to the plane of projection
An angle may project to appear larger or smaller than the true angle depending on its position

16. Irregular Objects

17. Irregular Objects

18. Curves in Isometric

19. Ellipses in Isometric
If a circle lies in a plane that is not parallel to the plane of projection, the circle projects as an ellipse
Ellipses can be constructed using offset measurements

20. Ellipses in Isometric
Approximate ellipses can be constructed from arcs

21. Drawing Isometric Cylinders

22. Screw Threads in Isometric
Parallel partial ellipses equally spaced at the symbolic thread pitch can be used to represent screw threads

23. Arcs in Isometric

24. Intersections

25. Spheres in Isometric

26. Isometric Sectioning
Isometric sectioning is useful in drawing open or irregularly shaped objects

27. Isometric Dimensioning
Isometric dimensions are similar to dimensions on multiview drawings but should match the pictorial style

28. Exploded Assemblies

29. Piping Diagrams

30. Dimetric Projection
A dimetric projection is an axonometric projection of an object where two of its axes make equal angles with the plane of projection and the third axis makes either a smaller or a greater angle

31. Dimetric Projection

32. Trimetric Projection
Trimetric projection is an axonometric projection where no two axes make equal angles with the plane of projection
Each of the axes have different ratios of foreshortening

33. Ellipses in Trimetric

34. Axonometric Projections Using Intersections
Before computer automated drafting, a method was devised to create axonometric projections using projections from orthographic views

35. Axonometric Projections Using Intersections