Transcript ENGR 2220 Inter

Lecture
2
Computarized Engineering Graphics
ENGR 2220
Department of Mechanical Engineering
Inter American University of Puerto Rico
Bayamon Campus
Dr. Omar E. Meza Castillo
[email protected]
http://www.bc.inter.edu/facultad/omeza
Inter - Bayamon
ENGR 2220
Course Objectives
 Upon successful completion of the course, the
student will be able to:
1.
Identify types of software and hardware used for computeraided design.
2. Clearly represent and control mental images.
3. Graphically represent technical designs, using accepted
standard practices.
4. Use plane and solid geometric forms to create and
communicate design solutions.
5. Describe the engineering design process.
6. Understand concepts and applications of 3-D modeling.
7. Understand the theory, techniques and standards of
multiviews.
8. Apply the concept of cutting planes to create section views
and sectioned 3-D .CAD models.
9. Apply the standard dimensioning practicing for mechanical
drawings.
10. Apply tolerances to dimensions
2
Lecture 2
Inter - Bayamon
ENGR 2220
Tentative Lecture Schedule
Topic
Lecture
Introduction: Graphics Communication /The Engineering
Design Process and Design Visualization
1
Preliminary Learning: Standard/Instruments for
Engineering Graphics
2
Sketching-2D: construction/Orthographic
Projection/Dimensioning
3
Software -2D: Basic commands/Drawing of Basic
Geometric/Drawing Multiviews and dimension placed
4
Sketching-3D: Projections Theory “Axonometric /Oblique
Projections”, Section Views and Assembly Drawing
5
Software- 3D: Isometric drawing, Solid Modeling and
Surfaces, Working Drawings and Assemblies
6
3
Lecture 2
Inter - Bayamon
ENGR 2220
Reference


Bethune, James. Engineering Graphics with AutoCAD
2009, Prentice Hall, 2009.
Earle James. Engineering Design Graphics, 11th Ed.,
Pearson Prentice Hall. 2005.
4
Lecture 2
Inter - Bayamon
"Lo peor es educar por métodos basados
en el temor, la fuerza, la autoridad,
porque se destruye la sinceridad y la
confianza, y sólo se consigue una falsa
sumisión”
Einstein Albert
Chapter 2: Instrument for
Engineering Graphics
ENGR 2220
Technical Drawing Tools
5
Lecture 2
Inter - Bayamon
 Scales (scale rulers) are used
distances on technical drawings.
to
measure
ENGR 2220
 There are many different scales. The most
important ones are Metric, Civil and Architect’s.
We
also
have
Mechanical
Engineering
or
Combination that we don’t review in this course.
 An architect’s scale is used to create drawings of
structures, such as a building or a factory floor
layout.
 The civil engineer’s scale is a decimal scale divided
into multiple units of 10 and is called a fully
divided scale.
6
Lecture 2
Inter - Bayamon
ENGR 2220
Metric Scales
Civil Scales
Architect’s Scales
7
Lecture 2
Inter - Bayamon
ENGR 2220
 Metric scale:
 The
international
organization
that
established the metric standard is the
International
Standards
Organization
(ISO).
The
system
is
called
the
International System of Units or Systeme
Internationale, abbreviated SI.
The
metric scale is used to create scaled
technical drawings using SI units.
8
Lecture 2
Inter - Bayamon
A standard ruler measurement is usually about a foot long, or in metric
terms, about 30 centimeters. You will find the ruler marked with lines
which are designated with numbers from 1 to 30 and between each set
of numbers, there are smaller lines which indicate the number of
millimeters. Ten millimeters or mm equal 1 centimeter or cm, hundred
cm equals one meter and so on. To measure the length between two
points on a paper or other medium, place the ruler with the first
centimeter line (which can be tagged as zero) on the first point. Mark
the number at which the second dot on the paper corresponds to the
centimeter reading, on the ruler. For example, with one point placed
against the zero mark and the second point shows a reading of 3. In
this case, the distance in centimeters between the two points is 3cm. If
the point is actually placed at a point beyond 3 but well within the line
depicting 4, count the smaller lines which show the millimeter scale
and count the number of lines at which the point rests, say at the 5th
small line, in which case the distance between the two points is 3.5cm
or 35mm.
3.5 cm=35 mm
ENGR 2220
Goes to 30 cm
3 cm=30 mm
9
Lecture 2
Inter - Bayamon
ENGR 2220
The metric scale ruler has 3 sides and there are 6
different scales on this scale.
The number on each corner refers to the scale on the
drawing. For example 1:125 on this scale means: every
millimeter on the drawing is equal to 125 millimeters
in real life. We write this scale as
1 mm=125 mm
or
Scale = 1/125
10
Lecture 2
Inter - Bayamon
ENGR 2220
Metric scales:
There are 6 scales to use.
11
Number
Scale
1:1
1
1:10
1/10
1:2
1/2
1:20
1/20
1:5
1/5
1:50
1/50
Lecture 2
Inter - Bayamon
How long is this match?
Every 10 divisions on this scale are 10 mm (as
shown). The match is longer than 20 mm. You have
6 divisions after 20, which are equal to 6 mm. So it
is 26 mm long!
ENGR 2220
What is the scale?
Scale is 1
or 1 mm=1 mm
12
Lecture 2
Inter - Bayamon
How long is this screw?
Every 10 divisions on this scale are 200 mm (as
shown). So every division is 20 mm. The screw is
longer than 400 mm. You have 2 divisions after 400
mm which are equal to 2x20=40 mm. So it is 440
mm long!
What is the scale?
ENGR 2220
1/20 or 1 mm=20 mm
13
Lecture 2
Inter - Bayamon
How long is this knife?
Every division on this scale is 5 mm (as shown in
the corner). So every 20 division are equal to 100
mm (shown for the first number). The knife is
longer than 300 mm. You have 7 divisions after 300
mm which are equal to 7x5=35 mm. So it is 335
mm long!
What is the scale?
ENGR 2220
1/5
or 1 mm=5 mm
14
Lecture 2
Inter - Bayamon
ENGR 2220
 Civil scale:
 The civil engineer's scale is a decimal
scale divided into multiple units of 10 and
is called a fully divided scale.
15
Lecture 2
Inter - Bayamon
10’
Each Scale
represents any
quantifiable item in
multiples of ten.
10’
10’
10’
ENGR 2220
10’
10’
16
Lecture 2
Inter - Bayamon
ENGR 2220
Civil scales:
There are 6 scales to use.
Number
Scale
10
1"=10’
50
1"=50’
20
1"=20’
40
1"=40’
30
1"=30’
60
1"=60’
Every inch on
the drawing is
equal to 60 feet
in real life!
17
Lecture 2
Inter - Bayamon
ENGR 2220
Regardless of the number you see on the corner
(here 10), every division of the scale is always 1 foot
in real life (for this course we consider the most
common case).
Always count the number of divisions and that is the
measurement in feet. Below, you see 17 divisions,
which are equal to 17 feet and 26 divisions which are
equal to 26 feet!
This is actually one inch, which is equal to 50 feet in
real life! So a civil engineer can use this scale to
draw bridges and other long structures.
18
Lecture 2
Inter - Bayamon
ENGR 2220
How long is this bridge in real life?
19
Lecture 2
Inter - Bayamon
The bridge is longer than 120 feet. Remember that
each number should be multiplied by 10 to show the
actual number in feet. It is 3 divisions more or 3 feet.
So the bridge is 123 feet long.
What is the scale?
ENGR 2220
20 feet
40 feet
60 feet
120 feet
20
1 " =50’
Lecture 2
Inter - Bayamon
ENGR 2220
There are other possible scales for each scale
ruler that we choose, but for this course we focus
on the most common case.
21
Lecture 2
Inter - Bayamon
ENGR 2220
How long is the
width of this small
cottage in real
life?
22
Lecture 2
Inter - Bayamon
The width of the cottage is longer than 20 feet.
Remember that each number should be multiplied by
10 to show the actual number in feet. It is 4 divisions
more or 4 feet. So the bridge is 24 feet long.
What is the scale?
ENGR 2220
10 feet
20 feet
30 feet
23
1 " =20’
Lecture 2
Inter - Bayamon
 Architect’s scale:
 Architect's scales may be flat, with 4
scales, or have a symmetric 3-lobed crosssection, with 11 scales.
ENGR 2220
 So remember that for metric or civil
scales, we have a total of 6 scales,
whereas for architect’s scale, there are 11
available scales.
24
Lecture 2
Inter - Bayamon
ENGR 2220
Find the 11 scales on this Architect’s scale!
25
Lecture 2
Inter - Bayamon
ENGR 2220
Architect’s
scales:
There are 11
scales to use.
26
Number
Scale
16
1"=1’’
3/16
1"=3/16’
3/32
1"=3/32’
3/4
1"=3/4’
3/8
1"=3/8’
3
1"=3’
1½
1"=1 ½ ’
1
1"=1’
1/2
1"=1/2’
1/4
1"=1/4’
1/8
1"=1/8’
Lecture 2
Inter - Bayamon
ENGR 2220
Architect’s scales:
Divide the number on the corner by 12 to get the actual scale.
Number
Scale
or
16
1"=1’’
Full size or scale of 1
3/16
1"=3/16’
1/64
3/32
1"=3/32’
1/128
3/4
1"=3/4’
1/16
3/8
1"=3/8’
1/32
3
1"=3’
1/4
1½
1"=1 ½ ’
(3/2)/12 = 1/8
1
1"=1’
1/12
1/2
1"=1/2’
1/24
1/4
1"=1/4’
1/48
1/8
1"=1/8’
1/96
27
Scale
Lecture 2
Inter - Bayamon
ENGR 2220
1. Determine the scale of your plans. It will be labeled on the
plans and should be found in the bottom corner.
2. Turn the ruler to the corresponding scale factor. For
instance, if the plans read ¼ inch equals one foot, you will
use the ¼ inch scale on the ruler.
3. Measure the desired line starting from zero on the correct
scale. In this case, you would need to use the ¼ inch scale.
4. The measurement you calculate equals how many feet the
line actually is at full scale dimensions.
28
Lecture 2
Inter - Bayamon
Full size or scale of 1:
This is similar to the normal school box ruler.
Every inch has 16 divisions.
So each division is 1/16 ".
Count
the
number
of
divisions and divide by 16.
ENGR 2220
So 8 divisions are equal to
8/16 or 1/2 inches.
Watch this video
29
Lecture 2
Inter - Bayamon
ENGR 2220
Read this measurement.
This is one inch and 9/16 inches. You should write
it as 1 9/16 ".
Watch this video
30
Lecture 2
Inter - Bayamon
For the 10 remaining scales, we have a region on the left
or a small scale which always represents 1 foot.
How long is this line?
It is more than 3 feet and less than 3.5 feet. But
how do you find out how much it’s length exactly
is?
ENGR 2220
Small scale
31
Lecture 2
Inter - Bayamon
Align the right side of the line with number 3 and check
the small section on the left (step 2). You read 4 larger
marks in that small section (remember that we have 12
marks in that section representing 12 inches or 1 foot).
So the length of the line is 3 feet and 4 inches. You
write it as 3’-4 ".
Each foot on the
ENGR 2220
scale
has 24
divisions.
So
every
2
divisions is one
inch. Every 2
divisions
are
equal
to
1
larger mark that
we considered!
1 foot
4 32 1
32
Lecture 2
Inter - Bayamon
Read this
measurement.
This is equal to 3 feet
and something!
The smaller scale reads
something between 3”
and 6” (closer to 3”).
The
smaller
section
shows 5/16’
(5/16’)x12 " =15/4=3
¾ inch.
You can find this by
saying
that
each
division on the small
scale is in fact ¾ " .
ENGR 2220
?
So the length is 3'-3
¾"
6
3
33
Lecture 2
Inter - Bayamon
1" =1"
3/16 " =1’
or 1/64
3/4 " =1’
or 1/16
3 " =1’
1 " =1’
ENGR 2220
or full size
1/4 " =1’
Test yourself! Find all the scales?
3/32 " =1’
or 1/4
or 1/12
or 1/48
34
or 1/128
3/8 " =1’
or 1/32
1 ½ " =1’
or 1/8
1/2 " =1’
or 1/24
1/8 " =1’
or 1/96
Lecture 2
Inter - Bayamon
Read these two measurements.
A=?
B=?
ENGR 2220
The 3/32 scale numbers are circled by red. The other
numbers belong to the scale 3/16 on the left. Length A
is 3 feet more than 100 feet. So it is 103’-0”.
Length B is longer than A. It is A plus half way in the
smaller scale. The small scale is 1 foot or 12 inches and
half of it is 6 inches. So B= 103’- 6”
35
Lecture 2
Inter - Bayamon
Read these measurements.
A=?
B=?
C=?
D=?
1 inch= 8 divisions
ENGR 2220
This scale is 3 " =1’ (or ¼ of scale). The section that you see
is the small scale section which is 1 foot or 12 inches. So all
the measurements here are less than 12 inches!
This one foot has 12 divisions. Check the red circles.
Remember that each inch has 8 divisions. So each division is
1/8 ".
36
Lecture 2
Inter - Bayamon
ENGR 2220
So A=1/8 " , B=1 ½ " , C=8 " and D= 9 ½ " .
37
Lecture 2
Inter - Bayamon
Homework2  WebPage
ENGR 2220
Due, Thursday, February 02, 2012
Omar E. Meza Castillo Ph.D.
38
Lecture 2