Forging new generations of engineers. Sketching. Purpose Techniques Size and Proportion Alphabet of Lines Projections References. Contents Click Shape to go to section. PURPOSE. Contents. Purpose.
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Shows design details
Initialed and dated.
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.Size and Proportion
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
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
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
about .6mm(.032in) that show
the visible edges of an object.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.)
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.
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
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
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
How many lines from the
previous 2 slides can you
Front view is true
size and shape.
Width lines are
parallel with the
In Cavalier Oblique depth
is full size. This cube
has the same height, width
and depth dimensions
Depth in an oblique
Easiest of the pictorials
Depth lines are drawn
at an angle with the
All lines in the depth project
to one point (vanishing
point). The location of the
vanishing point is based
on your line of sight.
Note: The vanishing
point in this sample
is chosen for
In two point perspective
the depth lines converge on one
vanishing point (VP2) and the
width lines converge on the
other vanishing point (VP1).
The arrows represent the
line of sight associated
with each view.
Use the button
below to jump
view and the ortho
view on the next
Note how the views
are oriented. Each view is
adjacent to the other as
if they were unfolded
from a 3D shape.
Top and Right views
are used most often. You can
see how other views resemble
these three except they are not
as clear due to hidden lines.
Click to go back
to ISO view.
Views are projected onto planes
that exist on the face of that view.
Arrows show the direction of the
Views are projected onto planes
that exist on the opposite face of the
view you want to display. The
arrows show the direction
of the projection.
Most natural position.
Best shape description.
No hidden lines.
will be identical
All dimensions easily
shown on one view.
It is also possible to
have one view drawings
of objects that are flat
and have even thickness.
Gauges and gaskets are
two such objects. We
have a gauge here on the
Symmetrical parts. A third view
would be identical to the other
Second view is necessary for
An object line here takes precedence
over the center line. However we
draw short thin lines beyond the
object to show there is a center line
underneath the object line.
Object lines took precedence over
the hidden lines you would see
from the hole. The center line in
the top view would show the depth
of the hole as well as the right