1. Review:
Axonometric/Oblique Projections
Isometric Projection
Isometric view from multiview drawing
Lab:
“Sketching missing lines” p.125.
On A format draw an isometric view of on object from multiview drawing 54 (a) 1.

2. “Sketching missing lines” p.125.
Part 1. Find missing lines and draw them.
Part 2. On isometric grid paper draw an isometric view of each object.

4. On A format draw an isometric view of on object from multiview drawing 54 (a) 1

5. Axonometric
& Oblique
Projection

6. Axonometric Projection Type of axonometric drawing
Axonometric axis A B C D a b c
1. Isometric
All angles are equal. A B C D
Axonometric axis a b c
2. Dimetric
Two angles are equal. b a c
Axonometric axis
3. Trimetric
None of angles are equal.

7. Oblique Projection Line of sight Parallel & oblique to picture plane AD C B A B C D
Line of
sight

9. Type of Oblique drawing
Oblique Projection
Oblique drawing angle
60o
45o A D C B
30o B C D A
Type of Oblique drawing
1) Cavalier
2) Cabinet
Full
scale
45o
Half
scale
45o

10. Isometric Projection
& Isometric drawing

11. Isometric Projection All edges foreshorten about 0.8 time. Rotate 45
about vertical axis
Tilt forward (35o16’)
All edges foreshorten
about 0.8 time.

12. Isometric Drawing
Isometric drawing is a drawing drawn on an isometric axes using full scale.
Isometric projection
(True projection)
Isometric drawing
(Full scale)
Forshorten
Full scale

13. Positions of Isometric Axes
Isometric axes can be arbitrarily positioned to create different views of a single object.
Regular
isometric
Reverse axis
isometric
Long axis
isometric
View point is looking
down on the top of
the object.
View point is looking
up on the bottom of
the object.
View point is looking
from the right (or left)
of the object.

14. Distance in Isometric Drawing
True-length distances are shown along isometric lines.
Isometric line is the line that run parallel to any of the isometric axes.
Nonisometric lines
Isometric axes

15. Isometric
Sketching

16. Sketch from an actual object
1. Place the object in the position which its shape and features are clearly seen.
2. Define an isometric axis.
3. Sketching the enclosing box.
4. Estimate the size an and relationship of each details.
5. Darken all visible lines.

17. Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.

18. Sketch from an actual object
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Note
In isometric sketch/drawing), hidden lines are omitted unless they are absolutely necessary to completely describe the object.

19. Sketch from multiview drawing
1. Interprete the meaning of lines/areas in multiview drawing.
2. Locate the lines or surfaces relative to isometric axis.

20. Example 1 : Object has only normal surfaces
Top H
Front
Top View
Regular
Side W D
Front View H
Side View
Front
Side W D
Bottom View
Reverse
Bottom

21. Example 2 : Object has inclined surfaces
Nonisometric line y q H y x x W
Front View

22. Example 3 : Object has inclined surfaces
Nonisometric line y A C y B A

23. Example 4
Regular x y B D C E F
Front View A B A C
Reverse D F E

24. Circle & Arc in Isometric
In isometric drawing, a circle appears as an ellipse.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Sketch arcs that connect the tangent points.

25. Circle & Arc in Isometric
Four-centre method is usually used when drawn an isometric ellipse with drawing instrument.
Sketching Steps
1. Locate the centre of an ellipse.
2. Construct an isometric square.
3. Construct a perpendicular bisector from each tangent point.
4. Locate the four centres.
5. Draw the arcs with these centres and tangent to isometric square.

26. Example 5

27. Irregular Curve in Isometric
Steps
1. Construct points along the curve in multiview drawing.
2. Locate these points in the isometric view.
3. Sketch the connecting lines.