Fundamentals of Engineering

Isometric Pictorials and EllipsesGSMST

2

Objectives

Projections: The Four Basic TypesCreating Isometric sketchesSketching Ellipses

3

Projections: Four Basic Types

Orthographic Projections

Axonometric

Oblique Perspective

Pictorials

Note: Isometric is a special case of Axonometric

4

Introduction to Isometric Projection

• Isometric means equal measure• All planes are equally or proportionately shortened and tilted• All the major axes (X, Y, Z) are 120 degrees apart

CUBE

5

Making an Isometric Sketch

• Defining Axis

30o 30o

60o60o

Isometric Axis

7

Usage of the Grid Paper

Correct orientation Incorrect orientation

Note the alignment of the axes

8

Going From Isometric to Rectilinear

9

Object for Practice

10

DepthWidth

Height

Isometric Axis Convention

Making an Isometric Sketch

• Axis Convention

Front view

Choose the longest

dimension to be the width (or the depth) for optical

stability

11

Blocking in the ObjectBegin with Front Face

Front Face

Height

Width

12

Blocking in the Object: Add Side

Face

Height

Depth

Side Face

13

Blocking in the Object: Add Top Face

Top Face

14

Adding Detail Cut Outs – Part 1

15

Adding Detail Cut Outs – Part 2

16

Adding Detail Cut Outs – Part 3

17

Darken Final Lines - Part 4

Note: All visible edges will be darkened

18

Draw the Isometric

• Use Isometric Grid Paper• Block is 6 x 3 x 3

19

Isometric View

20

Draw the Isometric

21

Draw The Isometric

22

Sketching a Circle• Draw a square whose

sides are the diameter of the circle.

• At the center of each side define the point of tangency for the circle.

• Draw the diagonals of the square.

• Orient the paper so you can draw equal arcs to construct the circle

23

Isometric ellipsesIn an isometric drawing, the object is viewed at an angle, which makes circles appear as ellipses.

Holes

Cylinders

24

Ellipses Can be in Any of Three Planes

25

Sketching an Isometric of a Hollow Pipe

26

Step 1 – Creating the Base Box

Diameter

Diameter Length

27

Step 2 – Ellipse on Front Face

Lines to Tangent Points

- Lines to tangent points

- Corner to corner to get center

Tangent Points

28

Step 3 – Ellipse on Front Face

Tangent Points

Sketch in Arcs

29

Step 3 – Ellipse on Back Face and Profile

Draw Tangent Lines for Profile

Complete Visible Part of Back Ellipse

Repeat for ellipse on rear face

30

Step 4 – Ellipse for Hole on Front Face

Create Box for Hole

Sketch Ellipse

31

Isometric of Hollow Pipe

32

Summary

• Technical drawings are an effective communication media

• Projections of various types can be used

• Isometric projections and creating isometric sketches has been introduced

• Assignments will emphasize simple isometric sketches

33

Review Questions

1. _______ sketches present the object in a single view, with all three dimensions represented

2. _______ sketches present the object in a series of projections, each one showing only two of the objects’ three dimensions

3. Which among the following is NOT an isometric axes (Hint: Use the Isometric Grid paper for reference)?

a) b) d)c)120°

120°120°

60° 60°

240°

60°90°

34

• Follow Sketching and Text conventions.

• Title Information is required. Avoid labels on the sketch.

• Leave the construction lines – MUCH lighter and thinner than the finished lines

• Include centerlines on isometrics

Tips for Drawing Assignments

35

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.

Tips for Drawing Assignments

36

Tips for Pictorial ViewsIn pictorial views, hidden lines are not shown unless absolutely required for clarity, such as; 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.

37

In Class Assignment

Use Isometric Sketch Paper (ISP)