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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