lecture 2 computarized engineering graphics engr 2220 department of mechanical engineering inter...
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LectureLecture
22Computarized Engineering GraphicsComputarized Engineering Graphics
ENGR 2220 ENGR 2220
Department of Mechanical EngineeringDepartment of Mechanical Engineering
Inter American University of Puerto RicoInter American University of Puerto Rico
Bayamon CampusBayamon Campus
Dr. Omar E. Meza CastilloDr. Omar E. Meza [email protected]
http://www.bc.inter.edu/facultad/omeza
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Upon successful completion of the course, the Upon successful completion of the course, the student will be able to:student will be able to:1.1. Identify types of software and hardware used for computer-Identify types of software and hardware used for computer-
aided design. aided design.
2.2. Clearly represent and control mental images. Clearly represent and control mental images.
3.3. Graphically represent technical designs, using accepted Graphically represent technical designs, using accepted standard practices. standard practices.
4.4. Use plane and solid geometric forms to create and Use plane and solid geometric forms to create and communicate design solutions. communicate design solutions.
5.5. Describe the engineering design process. Describe the engineering design process.
6.6. Understand concepts and applications of 3-D modeling. Understand concepts and applications of 3-D modeling.
7.7. Understand the theory, techniques and standards of Understand the theory, techniques and standards of multiviews. multiviews.
8.8. Apply the concept of cutting planes to create section views Apply the concept of cutting planes to create section views and sectioned 3-D .CAD models. and sectioned 3-D .CAD models.
9.9. Apply the standard dimensioning practicing for mechanical Apply the standard dimensioning practicing for mechanical drawings. drawings.
10.10. Apply tolerances to dimensionsApply tolerances to dimensions
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Course ObjectivesCourse Objectives
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Tentative Lecture ScheduleTentative Lecture Schedule
TopicTopic LectureLecture
Introduction: Graphics Communication /The Engineering Introduction: Graphics Communication /The Engineering Design Process and Design VisualizationDesign Process and Design Visualization
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Preliminary Learning: Standard/Instruments for Preliminary Learning: Standard/Instruments for Engineering GraphicsEngineering Graphics
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Sketching-2D: construction/Orthographic Sketching-2D: construction/Orthographic Projection/DimensioningProjection/Dimensioning
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Software -2D: Basic commands/Drawing of Basic Software -2D: Basic commands/Drawing of Basic Geometric/Drawing Multiviews and dimension placedGeometric/Drawing Multiviews and dimension placed
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Sketching-3D: Projections Theory “Axonometric /Oblique Sketching-3D: Projections Theory “Axonometric /Oblique Projections”, Section Views and Assembly DrawingProjections”, Section Views and Assembly Drawing
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Software- 3D: Isometric drawing, Solid Modeling and Software- 3D: Isometric drawing, Solid Modeling and Surfaces, Working Drawings and AssembliesSurfaces, Working Drawings and Assemblies
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ReferenceReference
Bethune, JamesBethune, James. . Engineering Graphics with AutoCAD Engineering Graphics with AutoCAD 20092009, Prentice Hall, 2009., Prentice Hall, 2009.
Earle JamesEarle James. . Engineering Design GraphicsEngineering Design Graphics, 11, 11thth Ed., Ed., Pearson Prentice Hall. 2005.Pearson Prentice Hall. 2005.
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Technical Drawing ToolsTechnical Drawing Tools
Chapter 2: Instrument for Chapter 2: Instrument for Engineering Graphics Engineering Graphics
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"Lo peor es educar por métodos basados "Lo peor es educar por métodos basados en el temor, la fuerza, la autoridad, en el temor, la fuerza, la autoridad, porque se destruye la sinceridad y la porque se destruye la sinceridad y la confianza, y sólo se consigue una falsa confianza, y sólo se consigue una falsa sumisión”sumisión”
Einstein AlbertEinstein Albert
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Scales (scale rulers) are used to measure Scales (scale rulers) are used to measure distances on technical drawings. distances on technical drawings.
There are many different scales. The most There are many different scales. The most important ones are important ones are Metric, Civil and Architect’sMetric, Civil and Architect’s. . We also have Mechanical Engineering or We also have Mechanical Engineering or Combination that we don’t review in this course.Combination that we don’t review in this course.
An architect’s scale is used to create drawings of An architect’s scale is used to create drawings of structures, such as a building or a factory floor structures, such as a building or a factory floor layout. layout.
The civil engineer’s scale is a decimal scale The civil engineer’s scale is a decimal scale divided into multiple units of 10 and is called a divided into multiple units of 10 and is called a fully divided scale.fully divided scale.
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Metric ScalesMetric Scales
Architect’s ScalesArchitect’s Scales
Civil ScalesCivil Scales
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Metric scale:Metric scale: The international organization that The international organization that
established the metric standard is the established the metric standard is the International Standards Organization International Standards Organization (ISO). The system is called the (ISO). The system is called the International System of Units or Systeme International System of Units or Systeme Internationale, abbreviated SI. The Internationale, abbreviated SI. The metric scale is used to create scaled metric scale is used to create scaled technical drawings using SI units.technical drawings using SI units.
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A standard ruler measurement is usually about a foot long, or in metric 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 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 which are designated with numbers from 1 to 30 and between each set of numbers, there are smaller lines which indicate the number of of numbers, there are smaller lines which indicate the number of millimeters. millimeters. Ten millimeters or mm equal 1 centimeter or cm, hundred Ten millimeters or mm equal 1 centimeter or cm, hundred cm equals one meter and so oncm equals one meter and so on. To measure the length between two . To measure the length between two points on a paper or other medium, place the ruler with the first 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 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 the number at which the second dot on the paper corresponds to the centimeter reading, on the ruler. For example, with one point placed 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 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 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 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 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 5and count the number of lines at which the point rests, say at the 5 thth small line, in which case the distance between the two points is 3.5cm small line, in which case the distance between the two points is 3.5cm or 35mm.or 35mm.
Goes to 30 cm
3 cm=30 mm
3.5 cm=35 mm
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The The metric scale ruler metric scale ruler has 3 sides and there are has 3 sides and there are 6 6 different scales different scales on this scale.on this scale.
The The number on each corner number on each corner refers to the scale on the refers to the scale on the drawing. For example 1:125 on this scale means: every drawing. For example 1:125 on this scale means: every millimeter on the drawing is equal to 125 millimeters millimeter on the drawing is equal to 125 millimeters in real life. We write this scale as in real life. We write this scale as
1 mm=125 mm1 mm=125 mmoror
Scale = 1/125Scale = 1/125
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Metric scales:Metric scales:There are 6 scales to There are 6 scales to
use.use.
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
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How long is this match?How long is this match?
Every 10 divisions on this scale are 10 mm (as Every 10 divisions on this scale are 10 mm (as shown). The match is longer than 20 mm. You have shown). The match is longer than 20 mm. You have 6 divisions after 20, which are equal to 6 mm. So it 6 divisions after 20, which are equal to 6 mm. So it is 26 mm long!is 26 mm long!
What is the scale?What is the scale?
Scale is 1Scale is 1or 1 mm=1 mmor 1 mm=1 mm
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How long is this screw?How long is this screw?
Every 10 divisions on this scale are 200 mm (as Every 10 divisions on this scale are 200 mm (as shown). shown). So every division is 20 mmSo every division is 20 mm. The screw is . The screw is longer than 400 mm. You have 2 divisions after longer than 400 mm. You have 2 divisions after 400 mm which are equal to 2x20=40 mm. So it is 400 mm which are equal to 2x20=40 mm. So it is 440 mm long!440 mm long! What is the scale?What is the scale?
1/20 or 1 mm=20 mm1/20 or 1 mm=20 mm
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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?
1/5or 1 mm=5 mm
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Civil scale:Civil scale: The civil engineer's scale is a decimal The civil engineer's scale is a decimal
scale divided into multiple units of 10 and scale divided into multiple units of 10 and is called a fully divided scale.is called a fully divided scale.
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Each Scale Each Scale represents any represents any
quantifiable item in quantifiable item in multiples of ten.multiples of ten.
10’
10’
10’
10’
10’
10’
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Civil scales:Civil scales:There are 6 scales to use.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 Every inch on the drawing is the drawing is equal to 60 feet equal to 60 feet in real life!in real life!
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Regardless of the number you see on the corner Regardless of the number you see on the corner (here 10), (here 10), every division of the scale is always 1 foot every division of the scale is always 1 foot in real life in real life ((for this course we consider the most for this course we consider the most common casecommon case).).Always count the number of divisions and that is the Always count the number of divisions and that is the measurement in feet. Below, you see 17 divisions, measurement in feet. Below, you see 17 divisions, which are equal to 17 feet and 26 divisions which are which are equal to 17 feet and 26 divisions which are equal to 26 feet!equal to 26 feet!
This is actually one inch, which is equal to 50 feet in This is actually one inch, which is equal to 50 feet in real life! So a civil engineer can use this scale to real life! So a civil engineer can use this scale to draw bridges and other long structures.draw bridges and other long structures.
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How long is this bridge in real life?How long is this bridge in real life?
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The bridge is longer than 120 feet. Remember that The bridge is longer than 120 feet. Remember that each number should be multiplied by 10 to show the each number should be multiplied by 10 to show the actual number in feet. It is 3 divisions more or 3 feet. actual number in feet. It is 3 divisions more or 3 feet. So the bridge is 123 feet long.So the bridge is 123 feet long.
What is the scale?What is the scale?
1 " =50’1 " =50’20 feet20 feet40 feet40 feet 60 feet60 feet 120 feet120 feet
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There are other possible scales for each scale There are other possible scales for each scale ruler that we choose, but for this course we focus ruler that we choose, but for this course we focus on the most common case.on the most common case.
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How long is the How long is the width of this width of this small cottage in small cottage in real life?real life?
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The width of the cottage is longer than 20 feet. The width of the cottage is longer than 20 feet. Remember that each number should be multiplied by Remember that each number should be multiplied by 10 to show the actual number in feet. It is 4 divisions 10 to show the actual number in feet. It is 4 divisions more or 4 feet. So the bridge is 24 feet long.more or 4 feet. So the bridge is 24 feet long.
What is the scale?What is the scale?
1 " =20’10 feet 20 feet30 feet
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Architect’s scale:Architect’s scale: Architect's scales may be flat, with 4 Architect's scales may be flat, with 4
scales, or have a symmetric 3-lobed cross-scales, or have a symmetric 3-lobed cross-section, with section, with 11 scales11 scales..
So remember that for metric or civil So remember that for metric or civil scales, we have a total of 6 scales, scales, we have a total of 6 scales, whereas for architect’s scale, there are 11 whereas for architect’s scale, there are 11 available scales.available scales.
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Find the 11 scales on this Architect’s scale!Find the 11 scales on this Architect’s scale!
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Architect’s Architect’s scales:scales:
There are 11 There are 11 scales to use.scales to use.
NumberNumber Scale Scale
1616 1"=1’’1"=1’’
3/163/16 1"=3/16’1"=3/16’
3/323/32 1"=3/32’1"=3/32’
3/43/4 1"=3/4’1"=3/4’
3/83/8 1"=3/8’1"=3/8’
33 1"=3’1"=3’
1 ½ 1 ½ 1"=1 ½ ’1"=1 ½ ’
11 1"=1’1"=1’
1/21/2 1"=1/2’1"=1/2’
1/41/4 1"=1/4’1"=1/4’
1/81/8 1"=1/8’1"=1/8’
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Architect’s scales:Divide the number on the corner by 12 to get the actual scale.
NumberNumber Scale orScale or ScaleScale
1616 1"=1’’1"=1’’ Full size or scale of 1Full size or scale of 1
3/163/16 1"=3/16’1"=3/16’ 1/641/64
3/323/32 1"=3/32’1"=3/32’ 1/1281/128
3/43/4 1"=3/4’1"=3/4’ 1/161/16
3/83/8 1"=3/8’1"=3/8’ 1/321/32
33 1"=3’1"=3’ 1/41/4
1 ½ 1 ½ 1"=1 ½ ’1"=1 ½ ’ (3/2)/12 = 1/8(3/2)/12 = 1/8
11 1"=1’1"=1’ 1/121/12
1/21/2 1"=1/2’1"=1/2’ 1/241/24
1/41/4 1"=1/4’1"=1/4’ 1/481/48
1/81/8 1"=1/8’1"=1/8’ 1/961/96
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1.1. Determine the scale of your plans. It will be labeled on the Determine the scale of your plans. It will be labeled on the plans and should be found in the bottom corner.plans and should be found in the bottom corner.
2.2. Turn the ruler to the corresponding scale factor. For Turn the ruler to the corresponding scale factor. For instance, if the plans read instance, if the plans read ¼ inch equals one foot¼ inch equals one foot, you will , you will use the ¼ inch scale on the ruler.use the ¼ inch scale on the ruler.
3.3. Measure the desired line starting from zero on the correct Measure the desired line starting from zero on the correct scale. In this case, you would need to use the ¼ inch scale.scale. In this case, you would need to use the ¼ inch scale.
4.4. The measurement you calculate equals how many The measurement you calculate equals how many feetfeet the the line actually is at full scale dimensions.line actually is at full scale dimensions.
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Full size or scale of 1:Full size or scale of 1:This is similar to the normal school box ruler.This is similar to the normal school box ruler.
Every inch has 16 divisionsEvery inch has 16 divisions. . So each division is 1/16 ". So each division is 1/16 ". Count the number of Count the number of divisions and divide by 16.divisions and divide by 16.
So So 8 divisions 8 divisions are equal to are equal to 8/16 or 8/16 or 1/2 inches1/2 inches..
Watch this video
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This is one inch and 9/16 inches. You should write This is one inch and 9/16 inches. You should write it as it as 1 9/16 "1 9/16 "..
Read this measurement.Read this measurement.
Watch this video
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For the 10 remaining scales, we have a region on the left For the 10 remaining scales, we have a region on the left or a or a small scale small scale which always represents 1 foot.which always represents 1 foot.
How long is this line?How long is this line?It is more than 3 feet and less than 3.5 feet. But It is more than 3 feet and less than 3.5 feet. But how do you find out how much it’s length exactly how do you find out how much it’s length exactly is?is?
Small scaleSmall scale
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Align the right side of the line with number 3 and check Align the right side of the line with number 3 and check the small section on the left (step 2). You read 4 larger 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 small section (remember that we have 12 marks in that section representing 12 inches or 1 foot). marks in that section representing 12 inches or 1 foot). So the length of the line is 3 feet and 4 inches. You So the length of the line is 3 feet and 4 inches. You write it as write it as 3’-4 "3’-4 "..
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Each foot on the Each foot on the scale has 24 scale has 24 divisions. So divisions. So every 2 every 2 divisions is one divisions is one inch. Every 2 inch. Every 2 divisions are divisions are equal to 1 equal to 1 larger mark larger mark that we that we considered! considered!
1 foot1 foot
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Read this Read this measurement.measurement.
This is equal to 3 feet This is equal to 3 feet and something!and something!The smaller scale reads The smaller scale reads something between 3” something between 3” and 6” (closer to 3”). and 6” (closer to 3”). The smaller section The smaller section shows 5/16’shows 5/16’
(5/16’)x12 " =15/4=3 ¾ (5/16’)x12 " =15/4=3 ¾ inch.inch.You can find this by You can find this by saying that each saying that each division on the small division on the small scale is in fact ¾ " . scale is in fact ¾ " .
So the length is So the length is 3'-3 3'-3 ¾"¾"
?
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Test yourself! Find all the scalesTest yourself! Find all the scales?
3/16 " =1’ or 1/64 3/32 " =1’ or 1/128
1" =1" or full size
3/4 " =1’ or 1/16 3/8 " =1’ or 1/32
3 " =1’ or 1/4 1 ½ " =1’ or 1/8
1 " =1’ or 1/12 1/2 " =1’ or 1/24
1/4 " =1’ or 1/48 1/8 " =1’ or 1/96
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B=?
A=?
Read these two measurements.Read these two measurements.
The 3/32 scale numbers are circled by red. The other The 3/32 scale numbers are circled by red. The other numbers belong to the scale 3/16 on the left. Length A is numbers belong to the scale 3/16 on the left. Length A is 3 feet more than 100 feet. So it is 3 feet more than 100 feet. So it is 103’-0”.103’-0”.
Length B is longer than A. It is A plus half way in the 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 smaller scale. The small scale is 1 foot or 12 inches and half of it is 6 inches. So half of it is 6 inches. So B= 103’- 6”B= 103’- 6”
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Read these measurements.Read these measurements.
C=?
D=?
B=?A=?
This scale is 3 " =1’ (or ¼ of scale). The section that you see 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. is the small scale section which is 1 foot or 12 inches. So all So all the measurements here are less than 12 inches!the measurements here are less than 12 inches!This one foot has This one foot has 12 divisions. 12 divisions. Check the red circles.Check the red circles.
12
1 inch= 8 divisions
Remember that each inch has Remember that each inch has 8 divisions8 divisions. So each division . So each division is 1/8is 1/8 " ". .
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So A=1/8 " , B=1 ½ " , C=8 " and D= 9 ½ " .So A=1/8 " , B=1 ½ " , C=8 " and D= 9 ½ " .
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Due, Due, Thursday, February 02, 2012Thursday, February 02, 2012
Omar E. Meza Castillo Ph.D.Omar E. Meza Castillo Ph.D.
Homework2 Homework2 WebPage WebPage
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