Chapter 7 Computer-Aided Drafting and Design 173
3. Back up work weekly to another location
separate from the network server, such
as one or more portable media devices.
Work can be saved to CDs, DVDs, or flash fl
drives.
This is just a sample protocol and will
probably vary based on your unique situation
and your instructor’s recommendations.
When work is completed on a project
and the fi les do not need to be used on a
daily basis, an electronic fi le archive is typi-
cally created. An electronic archive typically
consists of all of the fi les related to a single
project. This may involve hundreds of files fi
and many different fi le formats. Some CAD
programs provide special tools for creating
fi le archives. No matter what method you use, fi
there are several important points to keep in
mind.
Files to be archived must be saved in
a format and on electronic media that will
be compatible with computer software and
hardware of the future. Hence, the long-term
usefulness of CAD fi les is of greater conse-
quence than how much storage space they
require. As with fi les in a currently active
project, archived fi les must be accessible so
that they can be located, opened, and edited
if needed. The same fi le naming conventions,
folder organization practices, and backup
procedures used for active fi les should also
be applied when assembling an electronic
archive.
CAD Systems and Software
There are many CAD software programs
available for a variety of applications. The
type of program used normally depends
on the application or drawing discipline for
which it is used. CAD programs range in
capability from simple 2D drawing programs
to advanced 3D modeling and presenta-
tion programs. While basic CAD programs
require relatively inexpensive hardware to
drive the system, higher-end programs may
require computer equipment costing several
thousands of dollars.
As discussed in Chapter 4, a basic CAD
system consists of a computer, a monitor
(display device), keyboard, pointing device,
and output device. Data is stored on the hard
drive of the computer or on portable media.
The primary component of the CAD system
is the software. The software is the set of
instructions that tells the computer what to
do and when to do it.
CAD software programs can be classi-
fied in several different ways. Some CAD fi
programs provide 2D drawing capability
only. These programs have many of the func-
tions discussed in this chapter, with the excep-
tion of 3D-based tools. Other CAD programs
are based on a specific type of 3D modeling,
such as solid modeling, surface modeling, or
parametric modeling. Some CAD modeling
software is specifically designed for mechan-
ical drafting and manufacturing applications.
There are also advanced modeling programs
used to create photorealistic renderings and
animations. The following sections discuss
some of the features provided by different
types of CAD software.
CAD Modeling Programs
Modeling programs are used to create
realistic definitions of objects using 3D
coordinates and a variety of 3D drawing
methods. Commands in the software are
used to construct a model in 3D space. The
resulting model can then be shown in a picto-
rial view to display the various features and
surfaces. Common 3D modeling commands
are discussed in Chapter 13.
Three of the most common types of
3D modeling are solid modeling, surface
modeling, and parametric modeling. In solid
modeling, objects called g g solids or solid models
are created to represent the entire mass of
an object. See Figure 7-20. A solid model
is considered to be defined from the actual
material making up the object. Solid models