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Section 3 Creating Technology
Oblique Sketches
Oblique sketches are similar to
isometric sketches. See Figure 13-26. In
isometric sketches, the front and side are
both at 30° angles. In oblique sketches,
only the side view is at an angle. The angle
is usually 45°. This corner can, however,
be any angle.
These sketches show the front view in
its true shape. Isometric sketches tend to
distort shapes such as circles and arcs. In
an isometric sketch, all circles are shown
as ellipses. In oblique sketches, circles in
the front view are actual circles. For this
reason, circular objects are better drawn
as oblique sketches. Also, products having
one surface that is the most important are
drawn in an oblique sketch. For example,
the front views of stoves, radios, and televi-
sions are what most people see. Therefore,
oblique sketches show these designs
better than isometric sketches do.
Oblique sketches are produced using
the same steps as isometric sketches.
See Figure 13-27. The designer begins
by drawing the axes. In oblique drawings,
the designer creates the oblique axes. The
oblique axes are composed of one vertical
line, one horizontal line, and one angled
line. There are two types of oblique axes:
right and left oblique. In the right oblique,
the angled line is drawn back and to the
right. In the left oblique, the line is drawn
back and to the left.
The designer uses the oblique axes
to block out the shapes. The same basic
shapes are used in oblique sketches. The
box, cone, pyramid, and sphere are all
created the same way as in the isometric
sketches. The cylinder is the only shape
created differently. When a cylinder
appears on the front of the object, it is
drawn as a circle. If it appears on the side
of the object, however, it is drawn as an
ellipse.
Once the shapes are blocked out, the
designer adds the details. The designer
again adds the outline and external
features. The last details to be added to
refined sketches are shading and shad-
owing. These details help to make the
sketch appear more real.
Perspective Sketches
The third type of pictorial sketch is a
perspective sketch. Perspective sketches
are often used in making refined sketches.
They are used to show how objects look
to the eye. Imagine yourself standing in
the middle of a road. As you look down
the road, the buildings get smaller. It looks
Oblique Drawing
Isometric Drawing
Figure 13-26. Oblique drawings show the front
view directly and the side at a 45° angle. Isometric
drawings are drawn with both the front and side
views at 30° angles.