The document discusses isometric and orthographic sketching techniques used in engineering design. It compares engineering drawings to sketches and explains that sketches are used in early conceptual design while drawings are for final production. Various methods for sketching objects in isometric and orthographic views are presented, including unfolding 3D objects, transferring between views using construction lines, and ordering of drawing different object surfaces. Students are assigned to practice these techniques by sketching a cell phone in isometric and orthographic views.

1. Isometric & Orthographic Sketching
Engineering Design
GE121
Isometric and
Orthographic Sketching
Lecture 3A
GE 121 – Engineering Design - 2009

2. Engineering Drawing vs. Sketching
Isometric & Orthographic Sketching
Engineering Drawings
Used as output of the design process to
communicate the final design for production
Precise lines and arcs, detailed, and almost
always to scale
Engineering Sketching
Used at conceptual stage of design
Freehand, general shapes and sizes, often
just ballpark dimensions, not to a precise
scale, but rather simply relative proportions
We will be primarily sketching
GE 121 – Engineering Design - 2009

3. Unfolding the ‘Glass Box’
Isometric & Orthographic Sketching
GE 121 – Engineering Design - 2009

4. Layout of Views
Standard Top Front & Right Side
Isometric & Orthographic Sketching
GE 121 – Engineering Design - 2009

5. Sketching - Oblique Representation
Isometric & Orthographic Sketching
GE 121 – Engineering Design - 2009

6. Sketching - Isometric Representation
Isometric & Orthographic Sketching
GE 121 – Engineering Design - 2009

7. Isometric to Orthographic
Isometric & Orthographic Sketching
Orthographic
Views are used
extensively in
engineering
Often, they must be
produced from a 3D
object or possibly
an existing
Isometric drawing
or sketch
GE 121 – Engineering Design - 2009

8. Isometric to Orthographic
Hints for Orthographic Sketching
Isometric & Orthographic Sketching
• Identify the major features and overall dimensions
• Use clean, crisp strokes
• Do not use straightedges or scales when sketching
• Start by drawing bounding boxes and a miter line,
using construction lines
• Align the views
• Use light construction lines to locate vertices and
edges
• Only measure dimensions along primary axes
• Map inclined and oblique faces between all three views
• Follow the precedence of lines
• Doublecheck to make sure there are no missing hidden
or center lines
• Darken all visible, hidden and center lines
GE 121 – Engineering Design - 2009

9. Iso to Ortho
Isometric & Orthographic Sketching
Block in the 3 views
using overall width,
height and depth
Front View first, then
project height and width
using construction lines
Make sure depth is the
same on Top and Right
Views
GE 121 – Engineering Design - 2009

10. Iso to Ortho
Isometric & Orthographic Sketching
Lightly block in major
features in each view
Place circles in views
where they look round
Begin darkening
major features
GE 121 – Engineering Design - 2009

11. Iso to Ortho
Isometric & Orthographic Sketching
Construction lines can
be used to project
location or size of one
feature to another view
A miter line can be
used to project Depth
dimensions
GE 121 – Engineering Design - 2009

12. Iso to Ortho
Isometric & Orthographic Sketching
Finish adding all final
lines
Be sure to add all
hidden and center lines
Darken all final lines
GE 121 – Engineering Design - 2009

13. Iso to Ortho
Isometric & Orthographic Sketching
Completed Sketch
with construction
lines erased
GE 121 – Engineering Design - 2009

14. Orthographic to Isometric
Isometric & Orthographic Sketching
Orthographic
drawings are
common in
engineering.
Visualizing or
creating the
Isometric View
is a critical
engineering skill
GE 121 – Engineering Design - 2009

15. Orthographic to Isometric
• Hints for Isometric Sketching
Isometric & Orthographic Sketching
●
Identify major features and overall dimensions
●
Use clean, crisp strokes
●
Do not use straightedges or scales when sketching
●
Start by drawing a bounding box, using construction lines
●
Only measure dimensions along the primary axes
●
Do not directly transfer angles from a multiview to a
pictorial
●
Use light construction lines to locate vertices and edges
●
Sketch faces roughly in this order:
●
Normal faces on the perimeter of the bounding box
●
Normal faces in the interior of the bounding box
●
Inclined faces
●
Oblique faces
●
Darken all object lines
GE 121 – Engineering Design - 2009

16. Ortho to Iso
Isometric & Orthographic Sketching
Set up Isometric Axis using
1 vertical line and 2 lines at
30 degrees from horizontal
Estimate the overall width
height and depth of the
object, and sketch the
edges of a block that would
completely enclose the
object
GE 121 – Engineering Design - 2009

17. Ortho to Iso
Isometric & Orthographic Sketching
Sketch the outline
of the front face
using lines parallel
and equal in length
to the two previous
height and width
edges
GE 121 – Engineering Design - 2009

18. Ortho to Iso
Isometric & Orthographic Sketching
 Sketch the outlines
of the top and side
faces using the
same basic
procedure as used
for the front face
 Begin sketching
start/end points of
major features
GE 121 – Engineering Design - 2009

19. Ortho to Iso
Isometric & Orthographic Sketching
 Begin darkening
major features as
they are developed
 Locate start/end
points of additional
and smaller features
GE 121 – Engineering Design - 2009

20. Ortho to Iso
Isometric & Orthographic Sketching
 Locate and sketch start/
end points for non-
isometric lines such as
the angled surface
 Sketch and darken the
non-isometric features
GE 121 – Engineering Design - 2009

21. Ortho to Iso
Isometric & Orthographic Sketching
Completed
Isometric
Sketch with
construction
lines erased
GE 121 – Engineering Design - 2009

22. Activity
Isometric & Orthographic Sketching
Sketch a closed cell phone in Isometric
View, and then in the 3 Standard
Orthographic Views (Front, Top and
Right Side)
If you complete early, attempt the same
with the phone in the open position
Reference Images on the following slide
for those without a cell phone to sketch
GE 121 – Engineering Design - 2009

23. Reference Images
Isometric & Orthographic Sketching
GE 121 – Engineering Design - 2009