Introduction to Projections
Four Basic Types
Note: An
Isometric is
special case
of an
Axonometric
Orthographic
Projections
Axonometric
Pictorials
Oblique
Perspective
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Introduction to Isometric Projection
CUBE
• The term Isometric literally means equal measure
• All planes are equally or proportionately shortened and
tilted
• All the major axes (X, Y, Z) are 120 degrees apart
2
Making an Isometric Sketch
• Defining Axis
60o
60o
30o
30o
Isometric Axis
3
Making an Isometric Sketch
• Axis Convention
Height
Width
Front view
Depth
Choose the longest
dimension to be
the width (or the
depth) for optical
stability
Isometric Axis Convention
4
Making an Isometric Sketch
• Axis Convention
Height
Depth
Isometric Axis Convention
Width
Choose the
longest dimension
to be the width or
the depth for
optical stability
5
Usage of the Grid Paper
Correct orientation
Incorrect orientation
Note the alignment of the axes
6
The Transformation Between
The Isometric Grid & Rectilinear Grid
7
Object for Practice
8
Blocking in the Object
Begin with Front Face
Front Face
Height
Width
9
Blocking in the Object
Add Side Face
Side Face
Height
Depth
10
Blocking in the Object
Add Top Face
Top Face
11
Adding Detail
Cut Outs – Part 1
12
Adding Detail
Cut Outs – Part 2
13
Adding Detail
Cut Outs – Part 3
14
Darken Final Lines
Part 4
Note:
All visible edges
will be darkened
15
Sketching a Circle
1. Draw a square whose
sides are the diameter
of the circle.
2. At the center of each
side define the point of
tangency for the circle.
3. Draw the diagonals of
the square.
4. Orient the paper so you
can draw equal arcs to
construct the circle
16
Isometric ellipses
• In an isometric drawing, the object is viewed
at an angle, which makes circles appear as
ellipses.
• Holes
• Cylinders
17
Ellipses Can be in Any of Three Planes
18
Sketching an Isometric
of a Hollow Pipe
19
Step 1 - Creating the Base Box
Diameter
Diameter
Length
20
Step 2 – Ellipse on Front Face
(Reference Technical Graphics, Section 4.2.7)
- Corner to corner to get center
- Lines to tangent points
Tangent Points
Lines to Tangent
Points
21
Step 3 – Ellipse on Front Face
Sketch in Arcs
Tangent Points
22
Step 3 – Ellipse on Back Face and Profile
Repeat for ellipse on rear face
Draw Tangent Lines for Profile
Complete Visible Part of Back
Ellipse
23
Step 4 – Ellipse for Hole on Front Face
Create Box for Hole
Sketch Ellipse
24
Isometric of Hollow Pipe
25
Tips for Drawing Assignments
• Title Information is required. Avoid labels on
the sketch.
• Title block on bottom with your name
• Leave the construction lines – MUCH lighter
and thinner than the finished lines
• Include centerlines on isometrics
26
Tips for Drawing Assignments
• Do not try to shade drawing – this is not a
pencil sketching class.
• Use grid paper. Try to sketch along grid lines.
Practice sketching straight lines and curves
on a grid sheet.
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Tips for Pictorial Views
• In pictorial views, hidden lines are not shown
unless absolutely required for clarity
• Non-visible bottom of a blind hole
• Important feature of object not in direct view
• In pictorial views, holes or notches without
bottom/end visible should be assumed to go
completely through the object.
• Centerlines are to be shown on all isometric
pictorials.
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