Thursday, October 21st 2004
Pictorials with AutoCAD
Class 8.2 : Using AutoCAD to Create
Pictorial Drawings
Learning Objectives
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Use AutoCAD to draw an oblique of an object
given orthographic views of the object
Select the best orientation of an object in pictorial
Define what makes a drawing a: cavalier oblique,
cabinet oblique, general oblique, isometric,
axonometric, perspective, or orthographic views
Use AutoCAD to generate Isometric Drawings of
objects given the orthographic views of the object.
Types
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Obliques
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OBLIQUE
Axonometrics
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–
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Cavalier
Cabinet
General
Isometrics
Dimetric, Trimetric
AXONOMETRIC
Perspectives
1,2,or 3 points
PERSPECTIVE
Cavalier Oblique
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Front view true size
Receding Axis Angle
(Normally 30°, 45°
or 60°) is Variable
Depth dimension
(receding axis) true
size
45° CAVALIER OBLIQUE
Cabinet Oblique
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Front view true size
Receding Axis Angle
(Normally 30°, 45° or
60°) is Variable
Depth dimension
(receding axis) half
size
General Oblique
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Front view true size
Receding Axis Angle
(Normally 30°, 45° or
60°) is Variable
Depth dimension
(receding axis)
between half (D/2)
and full size (D)
Angles in Oblique
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Angles in front view are drawn true size
Other angles must be located using coordinates
Appearance of angles may be distorted
D1
D1
D2
D2
ORTHOGRAPHIC VIEWS
PLOTTED ANGLES
Obliques
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Obliques are theoretical
drawings. In reality, you
can not actually view an
object as an Oblique
Thin parts look very good
as Obliques
Parts with angular features
on multiple planes are
difficult to draw as
Obliques
Circles in Oblique
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Drawn true size in front view
Drawn as ellipses on receding planes
Layout using a Rhombus
Today’s AutoCAD commands
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Drawing setup
–
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MOVE
– COPY
– TRIM
Review polar coordinates
used with copy and move:
Example: @1.2<45
ZOOM
General Concepts
–
Editing and inquiry
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Drawing Aids
Display control
–
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Keyboard Coordinates
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Object Snap
–
–
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ENDPoint
TANgent
NEArest
Display Control
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ZOOM -- scales the screen view to an area of the
drawing surface
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–
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“Window” will zoom down to a window
“All” will zoom out to show the larger of the drawn
entities or limits
Realtime allows you to shrink or enlarge the display in
real time.
PAN -- moves around on the drawing surface
Formats of Keyboard Coordinates
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Either absolute or relative
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–
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Absolute is the default
Precede relative coordinates with an @ sign
–
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Absolute -- references origin of drawing (0,0)
Relative -- references previously selected point
@10,20 or @ 10<45
Direct Distance
–
Enter a distance in the direction of the cursor and return
Grips
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Grips serve two purposes:
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–
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Basic editing of properties
Modification of size/location
Grips are the small hollow squares which appear
when you select an object
If you click on a hollow square grip, it will
become active and you can drag the grip to a new
location. The actual effect of this will vary
depending on what object and which grip you
select.
Modifying Properties via Grips
Once an object is selected and the grips are
visible, you can change the Layer, Linetype,
Color, and LineWeight by using the
properties toolbar at the top of the screen.
 Anytime you have an object activated with
grips, the properties toolbar modify the
object properties, not the drawing settings.
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Drawing Obliques in AutoCAD
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Always make a rough pencil sketch of the object first to
get an idea of what your drawing should look like.
Draw the front view as a flat orthographic view
Use the COPY command along with keyboard coordinates
to place the front view along the receding axis to represent
all frontal surfaces in the object
Connect the copies with lines representing the depth of the
object. Remember to use OSNAP to assist in this process
Use ERASE and TRIM as appropriate to remove unwanted
lines/arcs
Example
Example
Construction of an oblique
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Draw the front view
using normal
AutoCAD commands
and techniques
Construction of an oblique
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Use the COPY command to
replicate the front view to
depict the depth
Command: COPYE
Select objects: [Other corner:[ 11 found
Select objects:E
<Base point or displacement>/Multiple:
E
Base point: [
m
Second point of displacement:
@.8<40
E
Second point of displacement:
E
@1.8<40
Second point of displacement:
E
Construction of an oblique
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ERASE the portions
of the depth profiles
which will not be
seen.
Command: eraseE
Select objects:[
Select objects:[
…
Select objects: [
Select objects: E
Construction of an oblique

Add receding lines
using OSNAP and the
LINE command.
Command: lineE
From Point: endpE of[
To Point: endpE of[
To Point:E
…
Construction of an oblique
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TRIM and ERASE the
remaining lines which
would not be visible.
E
Command: TRIM
Select cutting edges: (Projmode = UCS,
Edgemode = No extend)
[1 found
Select objects:E
Select objects:
<Select object to Trim>/Project/Edge/Undo:
<Select object to
trim>/Project/Edge/Undo:
E
[
Exercise 8.2.1: Cavalier Oblique.
Use Template English1.dwt with a receding axis of 30º
Isometrics
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Axes equally
separated (120°)
H, W, and D
measurements are true
size along iso. axes
Angles must be
located by coordinates
Circles appear as
ellipses on all surfaces
Drawing Isometrics in AutoCAD
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Initially you should do a rough sketch of the object by hand
to get an idea of what your drawing should look like
Switch the crosshairs to isometric mode (snap, style, iso)
Draw the object using the LINE and ELLIPSE commands
Use F5 to toggle the current isometric plane
Use OTRHO and OSNAP to assist you in the drawing
Copy face planes along isometric axes and connect corners
similar to oblique method shown earlier
TRIM or ERASE any portions which are not visible
Using isometric snap
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If the crosshairs
are not set in
isometric mode,
use the Drafting
Settings dialog
box.
–
Right click on
snap button and
choose settings
Drawing Ellipses
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In isometrics, circular
features which lie on
the principal planes
are shown as ellipses
These MUST be
drawn using the
ELLIPSE command
with the Isocircle Command: ellipse [ENTER]
Arc/Center/Isocircle/<Axis endpoint 1>: I [ENTER]
option
Center of circle: [ENTER]
<Circle radius>/Diameter: [ENTER]
Individual Exercise;
Draw an Isometric pictorial of the object
shown on the next slide using AutoCAD.
 The grid is a .2” grid
 Use template English1.dwt
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Isometric Example
Individual Assignment
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41 B&C: Cabinet oblique
43 B&C: Cavalier oblique
48 C&D: isometric
49 C&D: isometric
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Due: Thursday 28 October 2004
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