1. SKETCHING

2. Contents Click Shape to go to section.
Purpose
Techniques
Size and Proportion
Alphabet of Lines
Projections
References

3. PURPOSE
Contents

4. Purpose
The main purpose of sketching is to convey ideas. Engineers have to use sketches to brainstorm ideas, as well as, to show others what they are working on or what should be designed. Sketches are also used to document measurements from the field before they are produced as solid models on the computer.

5. Do you want to be a good sketcher?
Practice

6. Purpose
Proper documentation in a notebook is essential. When proper documentation is made, ideas are not lost and projects can be duplicated. Figure 1 is a sample from a notebook where a sketch was made and notes as well as dimensions have been documented.

7. Proposed Notebook Sample
Size requirements.
Shows design details
Title
Initialed and dated.

8. TECHNIQUES
Contents

9. Sketching Techniques Line Types: Inclined Line Vertical Line
Horizontal Line

10. Sketching Techniques Finding the slope angle of an inclined line:
Equation:
tans = RISE/RUN
tans = 2/4
tans = .5
s = arctan .5
Run = 4
Rise = 2
Note: Rise and Run units
do not matter (As long as the
units are the same). You are
finding an angle. In the above
case, we are counting grid boxes.

11. Sketching Techniques
Sketching a Line.

12. Sketching Techniques
Sketching an Arc

13. Sketching Techniques
Sketching an Arc

14. Sketching Techniques Sketching a Circle 1) Setup the diameter
2) Square in the
3) Sketch
diagonals

15. Sketching Techniques Sketching a Circle 4) Identify triangle centers
5) Sketch arcs

16. Sketching Techniques Precision Measurement
Refer to Presentation in Principles of Engineering

17. SIZE AND PROPORTION
Contents

18. Size and Proportion
Although you have learned to draw lines and arcs, you can not communicate properly until you understand how to sketch with the correct size and proportion. Without proper size and proportion your sketch will not look right.
Size: Length, width, height, distance. How big is the object you are sketching?
Proportion: If two objects are five feet apart in real life, then those two objects must appear to be five feet apart in your sketch.

19. Size and Proportion How to create proper size and proportion.
Technique I
Using a pencil to measure.
Hold your pencil at arms
length as you see in Figure 2.
Use the top of the pencil and
your thumb as a distance for
the height of the window. This
distance will be used as a
reference for sketching the rest
of the house as we did in the
house on the next slide.
Figure 2

20. Size and Proportion How to create proper size and proportion.
Technique I
Using a pencil to measure.
As you see in the completed
house in Figure 3, the units
of the numbered dimensions
are in windows.
You should also notice that
the use of graph paper also
helps in creating proper size
and proportion.
Figure 3

21. Size and Proportion How to create proper size and proportion.
Technique II
Boxing in the sketch.
Figure 4
In Figure 4 we are sketching
a chair. We sketch the boxes
to the largest outside
dimensions of our final
object. Notice that light
construction lines are also
used to help guide us to
the proper size and
proportion.

22. Size and Proportion How to create proper size and proportion.
Technique II
Boxing in the sketch.
Figure 5
Finally we use our sketching
techniques for drawing arcs,
lines and circles to complete
our chair in Figure 5.
Notice the box we started
with is still existent as light
construction lines. These are
our guides for proportion and
size.

23. © Project Lead The Way, Inc.
ALPAHBET OF LINES
Contents
© Project Lead The Way, Inc.

24. Alphabet of Lines Short Break Line: A freehand
drawn line that shows where a part is
broken to reveal detail behind the part or
to shorten a long continuous part. (See
example of Long Break Line
on the next slide.)
Object Line: Thick lines
about .6mm(.032in) that show
the visible edges of an object.
Hidden Line: Lines used to
show interior detail that is not visible
from the outside of the part.
Center Line: Lines that define
the center of arcs, circles, or symmetrical parts.
They are half as thick as an object line.
Section Lines: Lines are used to
define where there is material
after a part of the object is cut away.
Construction Line: Very lightly
drawn lines used as guides to help draw
all other lines and shapes properly.
Usually erased after being used.

25. Alphabet of Lines Long Break Lines: Break lines are used
to either show detail or as in this case they can
be used to shorten very long objects that
do not change in detail. Notice that this part
is 12” long however we have shortened
the drawing with break lines to use
our space more efficiently.
Dimension Lines: Lines that are used to
show distance. Arrows are drawn on the
ends to show where the dimension line starts and ends.
The actual distance is usually located in the middle of this
line to let you know the distance being communicated.
Dimension lines are used in conjunction
with extension lines to properly
dimension objects.
Cutting Plane Line: A line used to
designate where a part has been cut
away to see detail. The arrows should
point in the direction that you are
looking at the cutout.
Extension Lines: Lines used to show where
a dimension starts and stops on an object.
Used with dimension lines to properly dimension
an object. The line is 1/16” away from the
part as to not get confused with the object lines
Leader Lines: Leader lines are used to
show dimensions of arcs, circles and to help
show detail. An arrow head is used to point
to the part you are dimensioning and the line comes
off the arrow point usually at a 45 degree angle.
At the end of this line a horizontal line is drawn
with a note at the end telling information
about what is being pointed at.
How many lines from the
previous slide can you identify
here?

26. Alphabet of lines Phantom Lines: Phantom lines are used
to identify alternate positions that a part my
take up. In this example we are using Phantom
lines to show that the door handle may only move
45 degrees from it’s horizontal
position.
How many lines from the
previous 2 slides can you
identify here?

27. 3-DIMENSIONAL PROJECTIONS
Contents
© Project Lead The Way, Inc.

28. Pictorial
Pictorial sketches are sketches that show height, width, and depth all in one view. There are three common types:
Isometric
Oblique
Perspective

29. are drawn at 30 degrees from
Isometric
Note one view shows
height width and depth.
Width and depth lines
are drawn at 30 degrees from
the horizon line.

30. Oblique Front view is true size and shape. Width lines are
parallel with the
horizon.
In Cavalier Oblique depth
is full size. This cube
has the same height, width
and depth dimensions
Depth in an oblique
pictorial is
distorted.
Easiest of the pictorials
to draw.
Depth lines are drawn
at an angle with the
horizon.

31. Oblique Width lines are parallel with the horizon.
Front view is true
size and shape.
Width lines are
parallel with the
horizon.
In Cabinet Oblique depth
is half size. This allows the view
to look more realistic.

32. Do you want to be a good sketcher?
Practice
First Slide