Multiviews
Orthographic
Projection
Planes
Hinges Orthographic (Ref. plane)
The above figure shows the 6 Multiviews as projected onto the walls of a glass box. Consider the
edges of the box as having hinges where shown. Unfolding the box gives the standard
placement for the six views.
The orientation of the block (the object being drawn) is chosen such that the Front view will show
the greatest contour, or most irregular shape. Thus the Front view of a car would be the side view,
while the Front view of a house would usually be the view from the street.
View Placement
Orthographic
Views
Top
Left
Back
Nearly identical,
seldom used views.
Front
Right
Bottom
The above figure shows the glass box unfolded at the hinges. Construction lines illustrate that
heights are equal in all elevation views (Back, Left, Front and Right) while depths are equal in
the Top, Bottom, and end (Left and Right) views (see next figure).
The Top, Front, and Right views are the most common. Since Left = Right, Back = Front, and
Bottom = Top, (except for edge visibility) the Left, Bottom, and Back views are seldom used.
Deciding between the Left and Right views is based on which view has the least hidden lines.
(Right view in the above example.)
Invisible or hidden lines are represented by a dashed line (as shown), and used to indicate an edge or
contour of the object that cannot be seen in the view. There are lots of rules for how invisible
lines should be drawn in manual drafting, but some of them are difficult to accomplish with
CAD systems, so we are not going to worry about them.
View Construction
45
B
Top
A
B
A
Front
Right
Ref. Plane
Here we see the three most common views. Note that distances measured from the reference plane
in the Top view equal distances from the reference plane in the Right view (that is depths are
equal). A 45 construction line can be drawn through the intersection of the continuation of
lines representing the same surface in two views to aide in projecting depths.
Note: The reference planes I have shown are not usually shown for the standard views. They are
often shown when drawing auxiliary views (a view drawn at an angle to show a surface true size
that is not true size in any of the six standard views). Also, the TOP and Front views are
aligned, are as the Front and Right views.
70
100
200
80
290
Rules for Drawing Orthographic Multiviews
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Draw the views in their proper positions. That is Top and Front in the same vertical line, and
Front and End views in the same horizontal line.
Select the most descriptive view as the Front, if the object does not have a predefined front
view.
Select the sequence of views with the fewest hidden lines (usually between Left and Right).
The width (distance from front to back) of the Top view is equal to that on the End views.
The length (left to right) of the Top view is the same as that of the Front view.
The height of the end views is the same as the Front view.
A surface that is parallel to a plane of projection (walls of the box) will show true size and
shape when projected onto that plane.
A line (edge) that is parallel to a plane of projection will show true length when projected
onto that plane.
A line that is inclined to a plane of projection will appear shorter when projected onto that
plane.
A line perpendicular to a plane of projection will appear as a point when projected onto that
plane.
A surface that is perpendicular to a plane of projection will appear as a line when projected
onto that plane.
A surface that is inclined to a plane of projection will appear foreshortened when projected
onto that plane.
Label the views; for example, Top, Front, Right, etc.
Place dimensions between the views to which they apply; for example you might dimension
width on the Front view between the Front and Top view.
Leave adequate room between views for dimensions.
Draw the views necessary to describe the part. Some parts require only two (most symmetric
cylindrical parts) and some may require four or more.
Steps to Drawing Orthographic Multiviews
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Block in the views of the object using the overall dimensions of H, W, and D.
Draw outlines for planes showing true size on each view.
Edit to remove blocks of material where you can (rectangular areas first is usually easier).
Draw holes or cylinders.
Add hidden lines.
Add centre lines. Use centre lines for circles, and for the rotational axis of symmetry of a
part. (ie. The side view of the axis of a cylindrical hole.)
Dimension as necessary.