lecture 3 computarized engineering graphics engr 2220 department of mechanical engineering inter...
TRANSCRIPT
LectureLecture
33Computarized 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
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
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
22
Course ObjectivesCourse Objectives
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
33
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
11
Preliminary Learning: Standard/Instruments for Preliminary Learning: Standard/Instruments for Engineering GraphicsEngineering Graphics
22
Sketching-2D: construction/Orthographic Sketching-2D: construction/Orthographic Projection/DimensioningProjection/Dimensioning
33
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
44
Sketching-3D: Projections Theory “Axonometric /Oblique Sketching-3D: Projections Theory “Axonometric /Oblique Projections”, Section Views and Assembly DrawingProjections”, Section Views and Assembly Drawing
55
Software- 3D: Isometric drawing, Solid Modeling and Software- 3D: Isometric drawing, Solid Modeling and Surfaces, Working Drawings and AssembliesSurfaces, Working Drawings and Assemblies
66
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
44
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.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Graphics CommunicationGraphics CommunicationPart 1Part 1
Chapter 3: Sketching, Text, Chapter 3: Sketching, Text, and Visualizationand Visualization
55
"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
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
66
Here’s what we talked about last time:Here’s what we talked about last time:
Lines may be defined as…….Lines may be defined as…….
1.1. A series of points in space organized in a rational A series of points in space organized in a rational orderorder
2.2. The shortest distance between two pointsThe shortest distance between two points
3.3. The geometry created by the intersection of two The geometry created by the intersection of two planes or surfacesplanes or surfaces
4.4. A set of points organized that have length and A set of points organized that have length and direction, but no thicknessdirection, but no thickness
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
77
The “Alphabet of Lines”…The “Alphabet of Lines”…
Lines have both style Lines have both style and precedence. and precedence.
Object (visible) lines Object (visible) lines are the are the MOST MOST important…then important…then hidden lines… then hidden lines… then center lines… etc.center lines… etc.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
88
Examples of line use and layout:Examples of line use and layout:
Note: Note:
The center line has The center line has many variations.many variations.
It’s job is to show It’s job is to show the theoretically the theoretically perfect center of perfect center of arcs, holes, circles, arcs, holes, circles, and cylinders.and cylinders.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
99
Applications of linesApplications of lines
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1010
SketchingSketching
1.1. Sketching is an important method Sketching is an important method of quickly communicating design of quickly communicating design ideas.ideas.
2.2. Sketching is a way of thinking as Sketching is a way of thinking as it is a method of recording ideas it is a method of recording ideas and communicating to others.and communicating to others.
3.3. Most new designs are first Most new designs are first recorded using design sketches. recorded using design sketches.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1111
Methods for creating drawings:Methods for creating drawings:
SketchesSketches Using T-Using T-squares, squares, triangles, triangles,
etc.etc.
CAD CAD produced produced drawingsdrawings
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1212
Sketching the idea (ideation sketch)Sketching the idea (ideation sketch)
Subsequent document sketchSubsequent document sketch
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1313
Multi-view sketchMulti-view sketch::Good for someone who understands technical drawingsGood for someone who understands technical drawings
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1414
NOTE: There are also NOTE: There are also “technical sketches” “technical sketches” used in industry which used in industry which may include notes, and may include notes, and several versions that several versions that show motion.show motion.
Pictorial view:Pictorial view:Good for communicating the design. Suitable for Good for communicating the design. Suitable for nontechnical people.nontechnical people.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1515
Sketching Grids:Sketching Grids:
A.A. Orthographic gridOrthographic grid
B.B. Isometric gridIsometric grid
C. Perspective gridC. Perspective grid
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1616
Sketching linesSketching lines
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1717
Sketching linesSketching lines
The line is built up from a sequence of 2, 3 or more passes with a pencil.The line is built up from a sequence of 2, 3 or more passes with a pencil.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1818
SketchingSketching
Hold your pencil correctly, and have a relaxed grip.Hold your pencil correctly, and have a relaxed grip.Use a strip of paper to draw lines parallel to the edges of the paper.Use a strip of paper to draw lines parallel to the edges of the paper.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
1919
SketchingSketching
Each side of the Each side of the square is equal to square is equal to the diameter of the diameter of the circle.the circle.
Draw the diagonals Draw the diagonals and mark the and mark the midpoints. On the midpoints. On the diagonals mark 2/3 of diagonals mark 2/3 of the distance between the distance between the center and each the center and each corner.corner.
Connect all Connect all the points.the points.
An alternative An alternative methodmethod
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2020
SketchingSketching
Examples of Examples of poorly drawn circles poorly drawn circles (with flat arcs and sharp corners) (with flat arcs and sharp corners)
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2121
Sketching techniques:Sketching techniques:
1- Proportion 1- Proportion is important. is important. It is the ratio between any two dimensions of an It is the ratio between any two dimensions of an object.object.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
22
Sketches use “proportion”, not scale!Sketches use “proportion”, not scale!
ProportionProportion allows the designer to use allows the designer to use approximate values to create a balanced approximate values to create a balanced looking object.looking object.
SketchesSketches are accurate freehand drawings are accurate freehand drawings which use single lines to represent edges and which use single lines to represent edges and features.features.
Multi-line sketching is NOT used in engineering Multi-line sketching is NOT used in engineering design. (Scribbling!)design. (Scribbling!)
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2323
2- Draw the 2- Draw the bounding bounding
box.box.
1- Consider 1- Consider the correct the correct proportion.proportion.
3- Draw the 3- Draw the construction construction
lines.lines.These are every These are every light thin lines light thin lines
representing the representing the details of the details of the
object.object.
4- Finish the 4- Finish the sketch with darker sketch with darker
lines.lines.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2424
You can use construction line to find the You can use construction line to find the centercenter of squares or of squares or rectanglesrectangles
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2525
Sketching Sketching identically proportioned identically proportioned squaressquares
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2626
Grid paper Grid paper is used to scale an object.is used to scale an object.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
2727
1.1. Stand at a distance,Stand at a distance,2.2. Hold a pencil at arm’s length in front of you,Hold a pencil at arm’s length in front of you,3.3. Align the tip of the pencil with one edge of a feature,Align the tip of the pencil with one edge of a feature,4.4. Mark the length of the feature with your thumb,Mark the length of the feature with your thumb,5.5. Translate the same length to your sketch.Translate the same length to your sketch.6.6. Repeat this for other lengths. Don’t change your position. Repeat this for other lengths. Don’t change your position.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
28
Classification of Sketches:Classification of Sketches:
Each classification of sketch Each classification of sketch has a particular purpose from has a particular purpose from production use… to technical production use… to technical illustration.illustration.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
29
QUESTION!QUESTION!How do you know when a sketch or How do you know when a sketch or CAD drawing is complete?CAD drawing is complete?
ANSWER:ANSWER: When the production people When the production people can make the part without having to ask can make the part without having to ask you any questions!you any questions!
Most drawings not only have views of Most drawings not only have views of the object, but also it include written the object, but also it include written notes and dimensions to aid in its notes and dimensions to aid in its production.production.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3030
Types of Lettering:Types of Lettering:
Simple Gothic Simple Gothic is is used for engineering used for engineering design. Notice that it is design. Notice that it is “san serif” (no hats or “san serif” (no hats or shoes!)shoes!)
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3131
Types of Lettering:Types of Lettering:
Inclined Gothic Inclined Gothic is is often used for often used for architectural drawings, architectural drawings, and various types of and various types of technical illustrations.technical illustrations.
(All the lettering used (All the lettering used in these presentations in these presentations is inclined gothic.)is inclined gothic.)
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3232
ProjectionProjection
Drawings use various Drawings use various types of types of projectionprojection (how (how we view the object), to we view the object), to enhance our ability to enhance our ability to visualize what we are visualize what we are being asked to see or being asked to see or understand.understand.
Let’s look at the various Let’s look at the various styles of projection used…styles of projection used…
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3333
Most common types of projections:Most common types of projections:1.1. MultiviewMultiview (Showing 2 dimensions) (Showing 2 dimensions)2.2. Pictorial Pictorial (Showing 3 dimensions)(Showing 3 dimensions)
OR
Most common types of projections:Most common types of projections:1.1. ParallelParallel2.2. Perspective projectionsPerspective projections
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3434
Pictorial Projection:Pictorial Projection:
Here’s how the same object may look using different projection Here’s how the same object may look using different projection styles.styles.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3535
Projection types:Projection types:
Projection type is Projection type is defined by the defined by the “line “line of sightof sight” from the ” from the observer.observer.
Let’s look at some of Let’s look at some of these…..these…..
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3636
Perspective:Perspective:
The The line of sight is cone-shapedline of sight is cone-shaped - which makes objects - which makes objects far away appear smaller to our view. Objects are not “true far away appear smaller to our view. Objects are not “true shape and size”.shape and size”.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3737
Parallel:Parallel:
The The line of sight is always parallelline of sight is always parallel regardless of how far regardless of how far away the object is from our view. This allows surfaces to be away the object is from our view. This allows surfaces to be drawn “true shape and size.drawn “true shape and size.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3838
Orthographic:Orthographic:
Ortho means “Ortho means “at 90 at 90 degreesdegrees”, and is a form ”, and is a form of parallel projection.of parallel projection.
Orthographic projections Orthographic projections are used to show several are used to show several views of the same object views of the same object in one drawing set.in one drawing set.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
3939
Orthographic:Orthographic:
The “The “principle viewsprinciple views“ “ should be chosen to show should be chosen to show the most detail of the the most detail of the object with the least object with the least number of hidden lines.number of hidden lines.
Here, the Here, the TOPTOP, , FRONTFRONT, , and and RIGHT SIDE RIGHT SIDE were were chosen.chosen.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Isometric:Isometric:
A type of parallel projection that represents all 3 dimensions in one image.A type of parallel projection that represents all 3 dimensions in one image.
4040
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
4141
Isometric sketchIsometric sketch
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Isometric representations of Isometric representations of circlescircles
4242
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
4343
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
4444
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
4545
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Isometric sketches of Isometric sketches of common objects.common objects.
4646
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Use a piece of scrap Use a piece of scrap paper and mark one paper and mark one half of the major axis half of the major axis (AC) and one half of (AC) and one half of the minor axis (AB).the minor axis (AB).
Place A on the center and mark two points representing C and two points Place A on the center and mark two points representing C and two points representing B (draw major and minor axes). Place C on the minor axis and representing B (draw major and minor axes). Place C on the minor axis and hold B on the minor axis at any time, then place a mark at point A. Repeat hold B on the minor axis at any time, then place a mark at point A. Repeat this and connect all the points.this and connect all the points.
½ Major Axis½ Major Axis ½ Minor Axis½ Minor Axis
4747
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
4848
Understanding what Center Lines do…Understanding what Center Lines do…
Center lines Center lines show the show the theoretical perfect center of theoretical perfect center of arcs, holes, and cylinders. They arcs, holes, and cylinders. They can be used to show symmetry, can be used to show symmetry, or used to aid in dimensioning or used to aid in dimensioning an object.an object.
Center lines Center lines NEVERNEVER start or start or stop on another line!stop on another line!
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
4949
Steps in creating a 3-view sketch… Steps in creating a 3-view sketch…
Step 1:Step 1:
Layout the 3 principle views you Layout the 3 principle views you have chosen with even margins have chosen with even margins between views and the outside between views and the outside border of your drawing area.border of your drawing area.
Step 2:Step 2:
Rough out the general shape of Rough out the general shape of each view.each view.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
5050
Steps in creating a 3-view sketch… Steps in creating a 3-view sketch…
Step 3:Step 3:
Transfer any data from one view Transfer any data from one view to its neighbor using “reverse to its neighbor using “reverse construction”. This can be done construction”. This can be done by using a “miter line”.by using a “miter line”.
Step 4:Step 4:
Add hidden and center lines to Add hidden and center lines to the necessary views.the necessary views.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
5151
Steps in creating a 3-view sketch… Steps in creating a 3-view sketch…
Step 5:Step 5:
Erase all unnecessary lines and Erase all unnecessary lines and “snap” the lines on your views.“snap” the lines on your views.
““Snapping” adds weight to the Snapping” adds weight to the lines in each view and makes lines in each view and makes the drawing easier to read.the drawing easier to read.
Step 6:Step 6:
Add notes and/or dimensions to Add notes and/or dimensions to complete your drawing.complete your drawing.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
5252
Here’s some tips on creating a multi-Here’s some tips on creating a multi-view drawing:view drawing:
1. Lightly sketch all the information that you know first.1. Lightly sketch all the information that you know first.
2. Use reverse construction to locate lines that may be 2. Use reverse construction to locate lines that may be
unknown such as compound angles.unknown such as compound angles.
3. Add all circles and other arcs to your drawing.3. Add all circles and other arcs to your drawing.
4. Snap all arcs and circles first, and then straight lines.4. Snap all arcs and circles first, and then straight lines.
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Week 3: Multiview Drawings 1Week 3: Multiview Drawings 1We have already seen how views are aligned with the surface of an object.
Using the “glass box” method of visualization helps us understand the relationship views have with one another, i. e. the front view is next to the top and right side views, etc.
5353
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Here we can see all the principle views of an object as the glass box is unfolded.
It is easy to see that some of the principle views have more detail through the use of object (visible) lines than others.
Always choose views that have the least amount of hidden lines in them and show the most detail.
5454
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Using miter and projection lines, we can easily transfer “space dimensions” between views.
5555
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Projection methods:Projection methods:
3RD Angle (US Standard)
ISO (1ST Angle Metric Standard)
NOTE:
Reverse construction methods work just as well in 1ST Angle projection.
5656
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Here, we can see that surface C is shown as both as object and hidden lines depending on the view we are looking at.
Remember: One definition of a “line” is that it is the geometry on the edge of a surface. (Surface C appears in its edge view in the front and top views.)
5757
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
When choosing which of the principle views to draw, When choosing which of the principle views to draw, remember these rules:remember these rules:
1.1. Choose as many views as it takes to show Choose as many views as it takes to show ALLALL the details of the object. The front view usually the details of the object. The front view usually shows the most detail, or best view of the shows the most detail, or best view of the
general shape of the object in its natural general shape of the object in its natural position.position.
2.2. Choose views that shows a majority of object Choose views that shows a majority of object (visible) lines, and a minimum of hidden lines.(visible) lines, and a minimum of hidden lines.
3.3. Choose views that show features as surfaces Choose views that show features as surfaces first, and as lines second.first, and as lines second.
5858
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Always try to draw Always try to draw views in their most views in their most natural position.natural position.
This is obviously more difficult to This is obviously more difficult to visualize!visualize!
5959
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Why is the left side view not required?Why is the left side view not required?
ANSWER: It doesn’t add any new information!ANSWER: It doesn’t add any new information!
6060
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Why is the left side Why is the left side view not required?view not required?
ANSWER: It has too many hidden lines!ANSWER: It has too many hidden lines!
6161
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Surfaces will appear as edges at times. Edges may Surfaces will appear as edges at times. Edges may be foreshortened (shorter than normal), or “True be foreshortened (shorter than normal), or “True Length” (TL).Length” (TL).
6262
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Oblique edge lines are Oblique edge lines are created by oblique surfaces.created by oblique surfaces.
These are surfaces that are These are surfaces that are neither true shape or true neither true shape or true size in any principle view.size in any principle view.
6363
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Even simple, Even simple, primitive shapes primitive shapes often need several often need several views to fully views to fully describe their describe their topology.topology.
6464
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
““Limiting Elements” are lines that show the outer Limiting Elements” are lines that show the outer boundaries of cylindrical or conical objects. How many boundaries of cylindrical or conical objects. How many views of such objects are usually needed to show its views of such objects are usually needed to show its shape?shape?
6565
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Remember:Remember: In multiview drawings, tangency is shown In multiview drawings, tangency is shown between to surfaces by the absence of any line.between to surfaces by the absence of any line.
Here, the arched and planar Here, the arched and planar surfaces are tangent.surfaces are tangent.
Arched and planar surfaces Arched and planar surfaces which are which are NOTNOT tangent. tangent.
6666
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Holes and cylinders may appear “True Shape and Size” Holes and cylinders may appear “True Shape and Size” (TSS), or foreshortened depending on the view in which (TSS), or foreshortened depending on the view in which they appear. (Foreshortened circles will appear as they appear. (Foreshortened circles will appear as ellipses.)ellipses.)
6767
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
6868
Draw the sketch of the following objectsDraw the sketch of the following objects
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
6969
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
7070
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
7171
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
7272
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
7373
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
7474
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
7575
Lecture 3Lecture 3EN
GR
2220 In
ter
- B
ayam
on
EN
GR
2220 In
ter
- B
ayam
on
Due, Due, Wednesday, February 08, 2012Wednesday, February 08, 2012
Omar E. Meza Castillo Ph.D.Omar E. Meza Castillo Ph.D.
Homework2 Homework2 WebPage WebPage
7676