isometrics - ccory
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Isometric
PictorialSketching
Classification of Sketches
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Isometrics
The Greek word Axon means Axis
And Metric means to measure
Axonometric projection is a parallel projectiontechnique used to create a pictorial drawing of anobject by rotating the object on an axis relative to aprojection or picture plane
Axonometric drawings are classified by the anglesbetween the lines comprising the axonometric axes. Isometric- All three angles equal
Diametric- Two angles equal
Trimetric- No angles equal
Advantages and Disadvantages
Lines are scaled (foreshortened) but can find scalingfactors
Lines preserved but angles are not
Projection of a circle in a plane not parallel to the projectionplane is an ellipse
Can see three principal faces of a box-like object
Some optical illusions possible
Parallel lines appear to diverge
Does not look real because far objects are scaled thesame as near objects
Used in CAD applications
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Pictorial projection
Not intended to give exact or true
view.
Not intended to transmit
dimensions, although sometimes
dimension is useful.
Useful when the information and
instructions to be given to non-
technical and untrained people.
Hidden lines are not shown in
isometric drawing.
Isometric projection
Isometric projection is a true representation of the isometric
view of an object
Isometric view is created by rotating the object 45 degree
about vertical axis, and tilting it forward 35 deg 16
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Isometric Projection vs. Drawing
Isometric Projection is produced at a scale of 0.816
Isometric projection is a true representation of theobject
Isometric Drawing is produced using a scale that isfull size
Isometric Drawing has the same proportion as anisometric projection but is larger by a factor of 1.23:1
Isometric drawings are almost always preferred overisometric projection because they are easier to
produce
Axonometric Projection
Type of axonometric drawing
Axonometric projection Trimetric Dimetric Isometric
a
b cTwo angles are equal.
b
a
c None of angles are
equal.
a
b cAll angles are equal.
Isometric axis
Dimetric axis
Trimetric axis
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Axonometric projection
Axonometric project ion Trimetric Dimetric Isometric
Selection of Isometric Axes
Main purpose of isometric view is to provide a pictorial view which
reveals as much detail as possible
Selection of principal edges is important
Figure shows different isometric views of the same block
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Posit ions of Isometric Axes
Isometric axes can be arbitrarily positioned to createdifferent views of a single object.
Regular
isometricReverse axis
isometric
Long axis
isometric
View point is lookingdown on the top ofthe object.
View point is lookingup on the bottom ofthe object.
View point is lookingfrom the right (or left)of the object.
Visual on Isometric Project vs.
Isometric Drawing
Isometric projection & Isometric drawing Isometric projection: drawn at scale of 0.816 Isometric drawing: drawn at full scale
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Distance in Isometric Drawing
Isometric l ine is the line that run parallel to
any of the isometric axes.
Isometric axes
True-length distances are shown alongisometric lines.
Nonisometric lines
Non-isometric lines
Non-isometric lines are the lines that are not parallel to anyof the iso-lines.
They are drawn by transferring the distance of X or Y from
multiview to iso-view, not the actual length itself.
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Isometric and Non-Isometric Lines and Planes
Isometric Planes
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Hidden Lines in Isometric
Otherwise- Hiddenlines are NOTshown in IsometricDrawings. It isrepresented as asolid looking object!
With isometric, remember
30, 30, Vertical
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Boxing-In Method for Creating
Isometric Drawings
Determine the Isometric viewpoint that clearlydepicts the features of the object, then draw theisometric axes that will produce that viewpoint
Construct isometric planes using overall Height(H), Length (L), and Depth (D) of the object sothat the object will be contained inside the box
Locate Details on the isometric planes
Darken in all visible lines and eliminate hidden
lines unless absolutely necessary to show them
STEPS
1. Positioning object.
2. Select isometric axis.
3. Sketch enclosing box.
4. Add details.
5. Darken visible lines.
Sketch from an actual object
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1. Positioning object.
2. Select isometric axis.
3. Sketch enclosingbox.
4. Add details.
Note In isometric sketch/drawing), hidden lines are omitted
unless they are absolutely necessary to completely
describe the object.
Sketch from an actual object
STEPS
5. Darken visible lines.
1. Interprete the meaning oflines/areas in
multiview drawing.
2. Locate the lines or surfaces relative to isometric
axis.
Sketch from multiview drawing
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Front View
Top View
Side View
Example 1 : Object has only normal surfaces
Bottom View
Bottom
Front
Side
Side
Front
Top
Regular
Reverse
WD
H
H
DW
Example 2 : Object has inclined surfaces
W
H
D
y
x Front View
y
x
Nonisometric line
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Nonisometric line
A
A x
y
x
xB
B
AB
C
C
C
x
y
Example 3 : Object has inclined surfaces
A
A
B
B
C D
E
D
EF
F
x
y
Front View
Regular
C
Example 4
Reverse
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Steps in Creating an Isometric Sketch
! !
Constructing
a Drawing Having
Non-Isometric Lines
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ConstructingDrawings with
an Oblique
Surface
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Locating Points or Irregular Shape
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Draw a square whosesides are the diameter
of the circle.
At the center of eachside define the point
of tangency for the
circle.
Draw the diagonals ofthe square.
Orient the paper soyou can draw equal
arcs to construct the
circle
Sketching a Circle
Isometric Representation of Circles
NO!!!
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Circle & Arc in IsometricIn isometric drawing, a circle appears as an ellipse.
2. Construct an isometric square.
3. Sketch arcs that connect the
tangent points.
Sketching Steps
1. Locate the center of an ellipse.
Circle & Arc in Isometric
3. Construct a perpendicular
bisector from each tangent point.4. Locate the four centers.
5. Draw the arcs with these centers
and tangent to isometric square.
Sketching Steps
Four-centermethod is usually used when drawn an
isometric ellipse with drawing instrument.
2. Construct an isometric square.
1. Locate the center of an ellipse.
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Sketching an Isometric Ellipse
! !
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Creating IsometricCylindrical Features
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Creating Partial Isometric
Cylindrical Features
Irregular Curve in Isometric
1. Construct points along the
curve in multiview drawing.
2. Locate these points in the
isometric view.
3. Sketch the connecting lines.
Steps
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True EllipseMethod
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Example 5
Al though isometr ic drawingis not intended to
transmit dimension,
sometimes dimensions are
placed to indicate the size.
Isometric dimensions
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