Transcript Drafting Conventions - ETP - Engineering Technology Pathways

Drafting Conventions
By: Brian Nettleton
This material is based upon work supported by the National Science Foundation under Grant No. 0402616.
Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s)
and do not necessarily reflect the views of the National Science Foundation (NSF).
Drafting Conventions
In the field of drafting there are many standards a draftsman
must follow in order to properly communicate a design to
others. A certain line type or symbol can tell the reader what
the type of material the design is made of, weather the surface
is machined or not, or if a hole is round or square. The
following slides contain basic drafting conventions that will
enable a designer to adequately communicate a design to
others.
Line Types
There are many types of lines in a
drawing. The following are some of
the basic ones.
Boarder lines outline the drawing
and contain information about the
drawing.
Object lines outline the edges of an
object.
Hidden lines show important object
lines that are not visible.
Center lines show the middle of a
round hole or circular object.
Extension lines extend from an
object to define a dimension
Dimension lines define the
parameters of a dimension.
Line Weight
The different types of lines in a
drawing need to have different
thicknesses to help the person
reading the drawing interpret it.
Boarder lines are always the
thickest lines. Object lines and
Hidden lines represent the edges
of the part and are the next size.
The other lines are drawn
thinner.
Dimensions
Dimensions are used to show the
size of an object. Dimensions are
made up of an Extension line and a
Dimension line. The Extension
lines extend from ends of the line
that is being dimensioned . The
Dimension line has arrows at the
end that point to the Extension line.
The Extension line also contains
the number that represents the
distance between the Extension
lines. Circular objects like holes
and fillets have a dimension line
that points to the center. Circular
objects are dimensioned in
diameter or radius.
Lettering
Lettering is an important part of
communicating ideas in a
drawing or sketch. Lettering is
used in dimensions, notes and
in the title block of a drawing.
All lettering should be in
capitals and be consistent in
size. When drawing letters,
multiple strokes should be used
in either a downward or left to
right motion.
Standards and Benchmarks
Standard 11: Students will develop abilities to apply the design
process.
J. Make two-dimensional and three-dimensional representations of the
designed solution.
Standard 17: Students will develop an understanding of and be able
to select and use information and communication technologies.
K. The use of symbols, measurements, and drawings promotes clear
communication by providing a common language to express ideas.