AutoCAD and Its Applications BASICS
Supplemental Material—Chapter 3
2016
Introduction to
Isometric Drawings
A pictorial drawing shows the height, width, and depth of an object in a single
view. The most common type of pictorial drawing used in the drafting industry is the
isometric drawing. An isometric drawing is a view in which all three axes appear
at equal 120° angles with the plane of projection. See Figure 3A-1. This supplement
focuses on commands and drawing aids that help you create 2D isometric views that
look 3D, as if the object tilts toward you. However, a 3D model provides a better way
to display isometric views for most applications. AutoCAD and Its Applications—
Advanced describes how to construct 3D models.
The term isometric means equal (iso) measure (metric). An isometric drawing has no
perspective. Therefore, edges that are equal in length are drawn equal in length. The angles
between the three principal planes and edges of an object are equal. See Figure 3A-2A. Lines
that are parallel to the isometric axes form measurable lines and are called isometric lines.
Figure 3A-1.
An example of a 2D mechanical part drawing with an isometric view used to help visualize
the product.
Isometric drawing view
8
7
6
5
4
3
2
1
4X 13.75 (=55)
22.5
F
13.75
F
5X Ø 5 THRU
Ø 10 5
Ø 0.1 M A B C M
E
E
25
12.5
C
B
D
D
10
22.5
10
45
10
67.5
C
C
100
50
2X R5 CF
2X R10
2X R10 CF
2X Ø 10 THRU CF
B
10
90
Ø 0.1 M A
Ø 0.1 M
25
A
B
10
UNLESS OTHERWISE
SPECIFIED DIMENSIONS ARE IN
MILLIMETERS (mm)
NOTES:
A
1. DIMENSIONING AND TOLERANCING PER
ASME Y14.5-2009.
2. REMOVE ALL BURRS AND SHARP EDGES.
TOLERANCES: ISO 2768-m
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Introduction to Isometric Drawings
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Figure 3A-2.
A—An isometric drawing creates equal angles between the three principal planes and edges
of an object. B—An example of an isometric drawing with isometric and nonisometric lines.
Nonisometric
lines
Top isometric
plane
120°
Right
isometric
plane
Left
isometric
plane
120°
120°
90°
30°
30°
A
B
The vertical edges of an object in an isometric view are parallel to each other and form isometric
lines 90° from horizontal. The horizontal edges of an object in an isometric view are parallel
to each other and form isometric lines 30° from horizontal. Lines that are not parallel to the
isometric axes cannot be measured and are called nonisometric lines. See Figure 3A-2B.
Circular features appear elliptical in an isometric drawing. The Isocircle option of
the ELLIPSE command, described in Chapter 4, allows you to construct isometric circles
and arcs easily. Isometric text uses a specific oblique angle and rotation depending on
the plane and drawing application. Chapters 9 and 10 cover AutoCAD text.
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Type
DSETTINGS
DS
SE
Type
GRID
[Ctrl]+[G]
[F7]
SNAP
Once you understand the geometric layout of an isometric view, you can use any point
entry method to construct an isometric drawing. Polar coordinates and dynamic input or
dimensional input are common basic point entry options for isometric construction because
they allow you to specify angles. Polar tracking set to 30° increment angles is also an effective method. One of the most useful aids for isometric drawing is isometric snap mode.
A quick way to switch isometric snap mode on and off is to pick the Isometric
Drafting button on the status bar. You can also use the Snap and Grid tab of the Drafting
Settings dialog box to set isometric snap. See Figure 3A-3. A quick way to access the
Snap and Grid tab is to right-click on the Snap mode button or pick the Snap mode
flyout on the status bar and select Snap Settings…. Pick the Isometric snap radio button
in the Snap type area to activate isometric snap.
Specify the snap increment using the Snap Y spacing: text box in the Snap spacing
area and the grid spacing using the Grid Y spacing: text box in the Grid spacing area.
You can only set the Y snap and grid spacing. The X spacing is not applicable because
the X axis relates to horizontal measurements. For the same reason, you must also
check 2D model space in the Grid style area to display the grid as a pattern of dots.
After you activate isometric snap mode, and grid mode, if desired, you are ready to
begin drawing. As shown in Figure 3A-3, the grid and crosshairs rotate to an isometric
orientation that aids in drawing objects at isometric angles. Figure 3A-4 shows the
steps required to construct an isometric cube using the LINE command. Apply the
same techniques to drawing other objects. Notice that isometric snap can be very
helpful when you are constructing isometric lines.
GRID DSETTINGS
Isometric Snap Mode
Type
SNAP
[Ctrl]+[B]
[F9]
Introduction to Isometric Drawings
2
Figure 3A-3.
Use the Snap and Grid tab of the Drafting Settings dialog box to specify isometric grid and
snap settings. To quickly toggle isometric snap on and off, pick the Isometric Drafting button
on the status bar.
Turn snap
on and off
Isometric
crosshairs
Pick to set
isometric
snap
Grid
rotates 30˚
Specify the isometric
snap increment
Turn grid
on and off
Check
when using
isometric
snap to
display the
grid as a
pattern
of dots
Specify
the grid
spacing
Isometric
Drafting
button and
flyout
Figure 3A-4.
Creating a 2 unit × 2 unit cube using isometric snap and grid. Other default drawing aids are
also on to help describe the construction process.
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Introduction to Isometric Drawings
3
Isometric snap and grid modes orient the snap and grid to isometric angles. You
can align the crosshairs with the left, right, or top isometric plane, depending on the
plane on which you plan to draw. Each of the three isometric planes is referred to as an
isoplane. See Figure 3A-5. Changing the isoplane is not required for drawing isometric
lines, but doing so can be helpful for visualization and drawing ease. You must change
the isoplane orientation to construct isometric circles and arcs using the Isocircle
option of the ELLIPSE command, described in Chapter 4. To specify the appropriate
isoplane, right-click on the Isometric Drafting button or pick the Isometric Drafting
flyout on the status bar and select from the list, or access the ISOPLANE command and
select an option. You can also press [F5] repeatedly to cycle through isoplanes.
ISOPLANE
Specifying the Isometric Plane
Type
ISOPLANE
[F5]
NOTE
When isometric snap is active, the crosshairs is always oriented with the specified
isoplane. The isoplane does not apply to window or crossing selection and similar
operations that use a box to make a selection.
NOTE
Some of the following activities require the use of a decimal-unit isometric template
with active isometric snap and grid modes. If you do not have such a template, create
it now. Then use it as indicated in these activities.
Figure 3A-5.
Adjusting the isoplane orientation of the crosshairs to match a specific isometric plane.
Left Isoplane
150° “X axis”
90° “Y axis”
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Right Isoplane
30° “X axis”
90° “Y axis”
Top Isoplane
150° “X axis”
30° “Y axis”
Introduction to Isometric Drawings
4
Activity 3A-1
1. Start a new drawing from scratch using the imperial format. Save the drawing
as ACT3A-1.
2. Pick the Isometric Drafting button on the status bar to activate isometric snap.
3. Access the Snap and Grid tab of the Drafting Settings dialog box. The Isometric
snap radio button should be selected. Enter .25 for the Y snap and grid spacing
values, and pick the 2D model space check box.
4. Toggle grid mode on from the status bar if it is not active.
5. Access the LINE command and use isometric snap and the grid to draw the
isometric view shown below. Change the isoplane orientation as appropriate
for drawing objects on each isometric plane. Do not dimension the drawing.
6. Resave and close the file.
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Introduction to Isometric Drawings
5
Activity 3A-2
For each of the following isometric drawings, start a new drawing using a
decimal-unit isometric template that includes active isometric snap and grid
modes. Draw an isometric part view similar to each drawing using dimensions of
your choice. Save the drawings using the file names shown.
1.
File name: ACT3A-2A
2.
File name: ACT3A-2B
3.
File name: ACT3A-2C
Continued
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Introduction to Isometric Drawings
6
4.
File name: ACT3A-2D
5.
File name: ACT3A-2E
6.
File name: ACT3A-2F
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Introduction to Isometric Drawings
7