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Exploring Drafting
not typically provide a complete description
of the model. In addition, model dimensions
often need to be moved or hidden in order to
conform with standard dimensioning practices.
Notes and callouts can be added to the
drawing to provide additional information.
There are also tools for adding other items to a
drawing, such as center marks and centerlines,
geometric dimensioning and tolerancing (GD&T)
symbols, surface texture symbols, and a
revision block.
When working with assembly drawings, it
is common to add a bill of materials. This is
a table in the drawing listing all parts in the
assembly. The bill of materials includes the
name and number of each part, along with
a part description, the quantity required, the
part material, and any additional required
information, such as the manufacturer name
and pricing. When a bill of materials is
inserted, the information is entered into the
table automatically by the software. The bill of
materials is linked to the model by default and
updates to refl ect any changes to the assembly.
For example, if a part is replaced or a part
description is changed, the bill of materials is
automatically updated.
These types of views are discussed in later
chapters. Assembly drawings often include
one or more exploded views, which display
the assembly parts “exploded” to show how
they fi t together. See Figure 7-35.
Once drawing views are inserted, they can
be dimensioned. There are typically two methods
for adding dimensions to a drawing. One
method is to add model dimensions, which
are automatically generated by the software.
Model dimensions are parametric and are
known as driving dimensions because they drive
the model geometry. If a model dimension is
edited, for example, the model geometry is
updated in both the part and drawing fi les.
Another method used to dimension a drawing
is to add reference dimensions, also referred to
as drawing dimensions. Reference dimensions
are created manually by the user and are not
parametric. Instead, they are driven by the
model geometry. A reference dimension is
updated when the model is edited, but changing
a reference dimension in a drawing does not
change the model geometry. When adding
dimensions, it is common to use a combination
of model and reference dimensions. Model
dimensions generated by the software do
Iaroslav Neliubov/Shutterstock.com
Figure 7-35. Exploded views are typically used in assembly drawings to show how the parts fit together.
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