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Engineering Graphics IV
Prof. Paul Kurowski
October 30, 2012
Engineering Graphics IV
Section Views Auxiliary Views
Dimensioning Tolerancing
Section Views
SectionViews
Clearly show interior features
Avoid confusing hidden lines
Cutting Planes Cutting planes define
section views Lines of sight are
perpendicular to the cutting plane
Section views are parallel to cutting plane and perpendicular to lines of sight
Objects shown in true size Cut surface is cross-
hatched
Cutting PlaneLines
Show where cutting plane passes through object
Represent edge view of cutting plane
Appear in views adjacent to section view
Full Section
Half Section
Offset Section
Broken Out Section
Sketch Section View
Solution
E-drawing
Sketch Section View
Solution
Cross Hatching (Section Lines)
General symbol (cast iron) used for most purposes and for sketching
Section lines are normally drawn at 45° from the horizontal but can be changed for adjacent parts in the same section
Normally section lines are not shown on thin parts Components like bolts are usually not sectioned
A) Cast Iron/ B) Sound C) Thermal General Insulation Insulation
D) Water E) Steel F) Titanium/ Refractory Material
G) Concrete H) Wood (across/along grain)
Auxiliary Views
What is an Auxiliary view?
It is an extra view of an object It is used when the 6 principal views don’t
describe an object (or some of its features) clearly or completely - in particular inclined features
It is used to show the true lengths of lines It is used to show the true size of planes
Why use an Auxiliary View?
None of these views shows the angled face in true size and shape.
An extra view is needed.
Constructing an auxiliary view It is an orthographic projection Lines of sight are perpendicular to the plane of the
feature (or object) The projection plane is perpendicular to the lines of sight
and parallel to the plane of the feature
Auxiliary Views
- Dimension on true size and shape views only- Use Auxiliary views if necessary
NO YES
Question
Which of the following is NOT true of an auxiliary view?A. They are used to show the true size and shape of
features
B. They are orthographic projections
C. They are used to replace the traditional multiviews
D. They are used when the traditional multiviews do not fully describe the object
Question
Which of the following is NOT true of an auxiliary view?A. They are used to show the true size and shape of
features
B. They are orthographic projections
C. They are used to replace the traditional multiviews
D. They are used when the traditional multiviews do not fully describe the object
Dimensioning
Multi-view Drawing
Specify: Size of
features Location of
features Details and
notes
Dimensioning
Dimensioning is necessary to specify: Size of features Location of features Details and notes for construction or
manufacture
Dimensioning is important in the communication of the design, from the designer to the manufacturer/contractor to the quality control inspection
Dimensioned Multi-View Drawing Units must be stated Typically inches or millimeters Mixed dimensions sometimes
used
Terminology and Standards
Leave gap Note arrow
direction Limits indicate
tolerance
Terminology and Standards
Use diameter for circles, radius for arcs
Show extra dimensions as reference only (or better, omit)
Plus/minus indicates tolerance
Question
Why are dimensions used?A. To specify the size of features
B. To specify the location of features
C. To specify details and notes for construction or manufacture
D. To fully communicate the design
E. All of the above
Question
Why are dimensions used?A. To specify the size of features
B. To specify the location of features
C. To specify details and notes for construction or manufacture
D. To fully communicate the design
E. All of the above
Good Drafting Practices Dimensioning
Show all necessary views
Bottom view shows important
features
Make sure center lines
are shown in all views!
Make sure views are aligned
NO YES
Don’t dimension hidden lines
NO
YESDimension visible lines if possible
Dimension to centre lines of cylindrical features and holes
NO YES
Remember to show centre lines!
Dimension the most descriptive view
Don’t over or under-dimension
Show necessary dimensions exactly once
All dimensions can be derived from given dimensions
Don’t show the same dimensions different ways
Don’t over-dimension
NO YES
Don’t crowd dimensions
NO YES
Extension lines should not cross dimension lines
NO YES
- Dimension on true size and shape views only- Use Auxiliary views if necessary
NO YES
Add Dimensions
Solution
More than one solution is possible
Add Dimensions
Solution
Add Dimensions
Solution
