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Exploring Drafting
Drawing Setup Functions
CAD drawings should be planned carefully
prior to beginning work. Making drawing
settings ahead of time increases effi ciency.
Drawing setup is an important part of the
CAD drawing process and should become a
normal routine when beginning a project.
Linear and angular measurements made
with CAD commands are typically based on
the current unit settings. A drawing can be set
up to use decimal inch, architectural, metric,
or engineer’s units. Units are typically set with
the Units command. The unit format selected
depends on the drafting discipline.
Regardless of the unit format used, objects
are drawn at full size in CAD drafting. This
means that an object 2″ × 3″ is drawn at that
size. The drawing scale determines the size of
the drawing when it is plotted. The drawing
scale is based on the size of the drawing media
to be used and is determined before beginning
a drawing. The drawing scale affects the size of
dimensions and text. A number of settings are
typically made in relation to the scale factor,
such as linetype scaling and text height.
Layers are normally also created during the
drawing setup process. Linetypes are assigned
into a drawing as many times as needed. This
is a powerful function that greatly increases
drawing productivity. Blocks are typically
created for commonly used symbols. For
example, blocks are used on architectural plan
drawings to represent items such as windows
and doors.
Many companies store hundreds of blocks
in symbol libraries. A symbol library is a
collection of related drawing symbols. See
Figure 7-12.
To create a block, the symbol is drawn and
saved with a name. It can then be inserted into
drawings. Many manufacturers and drafting
fi rms provide blocks of their products that can
be downloaded from websites on the Internet.
In some CAD programs, blocks may be
saved with attributes. Attributes are text strings
of information about the related block symbol.
For example, attributes may be created to
identify a product number, price, size, or
material. Attributes can be displayed along
with the symbol on the drawing, or they may
be set invisible. Attributes are commonly used
to create schedules. A schedule is a chart or table
used to list manufacturing and purchasing
information about parts and products on a
drawing.
Hex Bolt Hex Cap Screw Hex Nut Slotted Oval Screw
Slotted Panhead Screw Phillips Flathead Screw Slotted Roundhead Screw Slotted Flathead Screw
Square Bolt Square Nut
Fasteners-Inch
Goodheart-Willcox Publisher
Figure 7-12. A symbol library of fasteners used in mechanical drafting.
Copyright Goodheart-Willcox Co., Inc.