1. March 5, 2010 2-24 1. Quiz Monday on the following:
IOT POLY ENGINEERING
2-24
March 5, 2010
1. Quiz Monday on the following:
Describe the differences between isometric, perspective, and oblique drawings
On diagonal grid paper, draw an isometric based on given orthographic projections
Find the starting point for orthographic projections and isometric drafting

2. Review OBLIQUE 2-10 3 A way of showing depth, like isometric
IOT POLY ENGINEERING
2-10
Review OBLIQUE 3
A way of showing depth, like isometric
Part orthographic / part isometric:
One face is true form
Parallel lines behind; either:
Full scale
Half scale
Three-quarter scale
TYPE 3: PICTORIAL

3. Review PERSPECTIVE 2-10 3 TYPE 3: PICTORIAL
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2-10
Review PERSPECTIVE 3
Latin: perspicere – to see through
An approximate representation of an image as it is perceived by the eye.
The most characteristic feature of perspectives is that objects are drawn:
Smaller as their distance from the observer increases
TYPE 3: PICTORIAL

4. Review ISOMETRIC 2-10 3 TYPE 3: PICTORIAL From Greek: Equal Measure
IOT POLY ENGINEERING
2-10
Review ISOMETRIC 3
From Greek: Equal Measure
Isos: Equal
Metron: Measure
The scale along each axis of the projection is the same
True form parallel lines are shown as parallel (note colors below)
All isometrics: simple construction
TYPE 3: PICTORIAL
Isometric Cube:
1) all lines equal length;
2) all faces equal area;
3) perimeter is a hexagon

5. QUIZ REVIEW 2-24 Isometrics: Perspectives: Obliques:
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2-24
QUIZ REVIEW
Isometrics:
Parallel projection
True size (you can measure the lengths accurately)
Perspectives:
Shown as it is perceived by the eye
Object gets smaller the farther away it is
Obliques:
One face is orthographic projection
The rest of object is parallel projection

6. Quiz drawing will be an altered version of one of your homeworks:
QUIZ REVIEW
On diagonal grid paper, draw an isometric based on given orthographic projections
Quiz drawing will be an altered version of one of your homeworks:

7. HORIZONTAL STARTING POINT
1. Add width of front view to width of right view.
4.5” + 2” = 6.5”
2. Add the space we will put between: 1.5”
6.5” + 1.5” = 8”
3. Subtract from the total width.
10” – 8” = 2”
4. Divide by 2.
Horizontal Starting Point = 1”

8. VERTICAL STARTING POINT
1. Add height of front view to height of top view.
3” + 2” = 5”
2. Add the space we will put between: 1.5”
5” + 1.5” = 6.5”
3. Subtract from the total height.
7.25” – 6.5” = .75” = 3/4”
4. Divide by 2.
Vertical Starting Point = .375” = 3/8”

9. DRAFTING ISOMETRIC DRAWINGS
IOT POLY ENGINEERING
2-21
DRAFTING ISOMETRIC DRAWINGS
Describe an isometric view
Height
Width
Depth
(of the front view)
Technical Graphic Communication

10. DRAFTING ISOMETRIC DRAWINGS
Prepare drawing paper
Locate center of drawing space
Construction Lines
Technical Graphic Communication
45 degree triangle

11. DRAFTING ISOMETRIC DRAWINGS
Plot starting point of drawing
1) ½ W
2) ½ D
3) ½ H
Technical Graphic Communication
triangle
Starting Point

12. DRAFTING ISOMETRIC DRAWINGS
IOT POLY ENGINEERING
2-21
DRAFTING ISOMETRIC DRAWINGS
Complete isometric drawing
Technical Graphic Communication
Starting Point

13. SOLUTIONS

14. CLASSWORK – Drafting Isometrics
3 March 10
IOT POLY ENGINEERING
2-21
CLASSWORK – Drafting Isometrics
Draft the following isometrics on drawing paper (use dimensions previously given for left drawing): 2” 2” 1” 1” 1” 4”

15. Introduction to AutoCAD
IOT POLY ENGINEERING
2-24
Introduction to AutoCAD
AutoCAD is a communication technology tool:
Creating neat, accurate drawings and designs.
There are numerous features – we will concentrate on the most important ones.
Technical Graphic Communication
One of the most important actions within the AutoCAD program is the drawing of straight lines.
Before we learn the LINE command, let’s take a look at how we normally draw lines by hand.

16. Absolute Coordinates AutoCAD 0 1 2 3 4 5 6 7 8 9 10 Plot lines:
Plot lines:
FROM: TO:
1,1 1,5
1,5 4,9
4,9 7,5
7,5 7,1
1,5 7,5
3,1 3,4
3,4 5,4
5,4 5,1
0,1 10,1
AutoCAD

17. Absolute Coordinates 2-3
IOT POLY ENGINEERING
2-3
Absolute Coordinates
Absolute coordinates are based on the origin (0,0), expressed as an ordered pair x,y. All other points are also expressed in the form x,y and the values of x and y are based on the distance from the origin.
If we desire to draw a line, we must give the location of both endpoints, expressed as an ordered pair x,y where the origin is used as a reference point.

18. Relative Coordinates AutoCAD 0 1 2 3 4 5 6 7 8 9 10 Plot lines:
FROM: 0,1
@ 10,0
FROM: 1,1
@0,4
FROM: 0,5
@10,0
@5,2
@5,-2
FROM: 9,5
@0,-4
AutoCAD

19. What is the distance between the two orange lines?
Relative Coordinates
What is the distance between the two orange lines?
Offset distance = .5
Plot lines:
FROM: 3,1
@0,2
@1,0
@0,-2
FROM: 5,1
@0,3
@3,0
@0,-3
AutoCAD

20. Communication Technology Introduction to AutoCAD
IOT POLY ENGINEERING
2-24
Communication Technology Introduction to AutoCAD
Relative coordinates are not based on the origin (0,0). Instead, we use symbol followed by an ordered pair x,y. This means “starting where we are AT, go over (or back) x and up (or down) y.
If we desire to draw a line using relative coordinates, we must give the location of the first endpoint (usually using Absolute coordinates), followed for the second endpoint.

21. Relative Coordinates AutoCAD 2-24
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2-24
Relative Coordinates
In AutoCAD, you do not have to specify the start point with coordinates – you can just click anywhere.
AutoCAD

22. Absolute and Relative Coordinates
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2-24
Absolute and Relative Coordinates
On the graph paper provided, draw coordinate axes about half the size of your graph paper.
Draw an object with at least 10 lines.
The end points must land on intersections of graph paper lines.
Tear a blank sheet of notebook paper in half.
On one half, write out the absolute coordinates required to draw the object.
On the other half, write out the relative coordinates required to draw the object.
Someone else will be drawing your object based on the coordinates you create.
FROM: TO:
1,1 1,5
FROM: 0,5
@5,2
@5,-2

23. IOT POLY ENGINEERING
2-24
Homework
Trade absolute coordinates with someone in class. Put his/her name on a blank area of your graph paper, write the word “absolute,” and draw the object based on the coordinates.
Trade relative coordinates with someone in class. Put his/her name on a blank area of your graph paper, write the word “absolute,” and draw the object based on the coordinates.
Bring back your partner’s coordinate sheets tomorrow.