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ACHIEVING COMPETENCE IN PREPARING/INTERPRETING TECHNICAL DRAWING
SKETCHING
This is the first of the modular series produced by the Jacobo Z. Gonzales Memorial School of Arts and Trades – Technical Education and Skills Development Authority Region IV-A
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 1 of 18
TABLE OF CONTENTS
Content
Page Number
I.
LEARNING GUIDE OVERVIEW …………………………………... …….. 3
II.
HOW TO USE THIS GUIDE ……………………………………………….. 4
III.
LEARNING ACTIVITIES ……………………………………………………. 5
IV.
INFORMATION SHEET A. FORMS OF SKETCHES ………………………………………………. 6 B. TOOLS AND MATERIALS FOR SKETCHING ………………………. 7 C. TECHNIQUES FOR SKETCHING…………………………………….. 7 D. TYPES OF SKETCHES……………………………………………….. 8 E. CONCEPTS AND PRINCIPLES UNDERLYING MULTIVIEW, ISOMETRIC, OBLIQUE, AND PICTORIAL SKETCHING.………….. 9
V.
SELF CHECK ………………………………………………………………... 11
VI.
JOB SHEET 1. SKETCHING AN ISOMETRIC DRAWING ……………..……12 2. SKETCHING A MULTIVIEW DRAWING ……...……………. 14 3. SKETCHING CIRCLES……………………………………….. 17
VII.
ANSWER KEY ………………………………………………………………. 17
VIII.
RECORD OF COMPETENCE …………………………………….………. 18
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 2 of 18
LEARNING GUIDE OVERVIEW Sketching is one of the primary means of graphic communication. The ability to sketch is an essential tool in conveying original ideas from the engineer to the designer and from the designer to the drafter. As instrument drawing becomes less prevalent in industry, the ability to create accurate technical sketches becomes more important. In this learning material, the students should be able to communicate technical information through different types of sketches. This will cover the purpose of sketching, materials needed for sketching, techniques for sketching, the types of sketches, and differences between isometric, oblique and perspective and multiview sketches Competencies will be demonstrated by completing the job sheets and the unit test with a minimum score of 75 percent.
OBJECTIVES
When you have successfully completed the learning activities in this material, you will be able to: 1. Identify the concepts related to sketching; 2. Explain the concepts related to sketching multiview and pictorials; and, 3. Make multiview, isometric, oblique, and perspective sketches.
CONTENTS
This learning material includes the following: 1. Forms of Sketches 2. Materials for Sketches 3. Techniques for Sketching 4. Types of Sketches 5. Concepts and Principles Underlying Multiview, Isometric, Oblique, and Pictorial Sketching
PRE-REQUISITES
The completion of this learning material requires you to have a basic understanding of:
If you are unfamiliar with any of the above concepts, work on________ before working on this learning guide.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 3 of 18
HOW TO USE THIS LEARNING GUIDE This Learning Guide will lead you through a series of activities which will require you to work at your own pace. These activities will ask you to complete associated learning and practice activities in order to gain the knowledge and skills you need to achieve the learning objectives stated earlier. Refer to Learning Activity Page to know the sequence of learning tasks to undergo and the appropriate resources to use in each task. This page will serve as your road map towards the achievement of objectives. Read the information sheets. This will give you an understanding of the work, and why things are done the way they are. Complete the activities as directed in the activity/practice sheets. These will test your knowledge and give you practice of doing the tasks involved. Performance criteria for assessing practical exercise are shown to guide you in undertaking the practical exercises. Always be aware of safety requirements highlighted in this material. Ask for clearance in using some tools and equipment. Should you require some assistance and clarification, consult your trainer or facilitator. They should be available anytime you need them. Answer self-checks found in each section of the learning guide. Do not write anything on this learning guide; provide separate sheets for your answers. Self-checks will let you know how you are going. To know how you fared with self checks, review the answer keys found at the end of the learning guide. When you had completed all the tasks required in this learning guide, an assessment exercise will be given to evaluate if you are already competent with the specified learning outcomes in and ready for the next task. .If you feel ready for the assessment, consult the facilitator. A record of competency is provided on the last page to reflect how much of the required assessment criteria have been met. You may already have some or most of the knowledge and skills covered in this learner’s guide. Talk to your trainer about having them formally recognized. If you have qualification or certificate of competence from previous training, show it to your trainer. If the skills you acquired are still current and relevant to the unit of competency they may become part of the evidence you can present for Recognition of Prior Learning (RPL). If you are not sure about the accuracy of your skills, discuss it with your trainer.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 4 of 18
LEARNING ACTIVITIES In order to accomplish the objectives stated in this leaning guide, you must perform the learning steps below. Beside each step are the resources or special instructions you will use to accomplish the corresponding activity. RESOURCES/SPECIFIC INSTRUCTIONS
LEARNING STEPS
1. Student will ask the instructor of
1.
Instructor will provide the learning materials in Sketching
the materials to be used 2. Read: Information Sheet No. 1
2.
Information sheet No 1: Sketching
3. Answer: Self Check
3.
Self Check: Sketching
4. Perform: Job Sheet No. 1
4.
Job Sheet No. 1: Sketching an Isometric Drawing
5. Perform: Job Sheet No. 2
5.
Job Sheet No. 2: Sketching a Multiview Drawing
6. Perform: Job Sheet No. 3
6.
Job Sheet No. 3: Sketching Circles
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 5 of 18
INFORMATION SHEET NO: 1
SKETCHING Sketching is a freehand drawing process that allows detailers, designers, engineers, architects, technicians and tradespersons to record their ideas quickly on paper without the use of tools. Once they have recorded their ideas, they can revise and refine their sketches for presentation to their supervisors or clients. Sketching is also helpful in preliminary planning of a drawing or layout before using tools.
A. FORMS OF SKETCHES 1. Design sketches - Design sketches are rough sketches that are used to quickly capture an idea. They tend to have less detail, structure and restrictions than freehand or technical illustrations.
FIG. 1. A ROUGH SKETCH WITH NOTES ABOUT IMPORTANT FEATURES. 2. Freehand technical sketches - Freehand technical sketches can be multiview or pictorial sketches. This type of sketch usually includes more detail and structure than design sketches. They also typically include dimensions (see Fig. 2). 3. Technical illustrations - Technical illustrations include more detail, structure, and restrictions than other types of sketches. The objective here is to create a sketch that looks as close to the final object as possible.
FIG. 2. MULTIVIEW SKETCH
FIG. 3. A SKETCH CAN SHAPE A FUTURISTIC DESIGN.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 6 of 18
B. TOOLS AND MATERIALS FOR SKETCHING Paper You can use a plain paper for sketching. If you need to refine the sketch, use tracing paper. Control proportions while sketching by using cross-section paper, also called graph paper or squared paper. There are specially ruled graph papers for particular kinds of drawing such as isometric and perspective. You can sketch on any convenient size of paper. However, A4 size drawing paper will only be allowed for this course as an official drawing paper. Pencils and Eraser Most drafters like to use soft lead pencils (grades F, H or HB), properly sharpened. They also use an eraser that is good for soft leads, such as a plastic eraser or a kneaded-rubber eraser. Use drafter’s pencil sharpener to remove the wooden part of the pencil from the lead. Make the lead of the pencil sharp by using sandpaper block or pad. Four types of points are used for sketching: sharp, near-sharp, near-dull, and dull. The points should make the following kinds: • Sharp point—a thin black line for center, dimension, and extension lines • Near-sharp point—visible or object lines • Near-dull point—cutting-plane line and border lines • Dull point—construction lines
FIG. 4 FOUR CONVENIENT PENCIL POINTS FOR SKETCHING
C. TECHNIQUES FOR SKETCHING •
Horizontal lines should be sketched by moving the hand and pencil from the left to the right if right handed. Avoid rotating your wrist, as this will cause the line to arc. FIG. 5. DIRECTION OF PENCIL IN SKETCHING HORIZONTAL LINE IS FROM LEFT TO RIGHT
•
Vertical lines should be sketched by moving the hand and pencil from the top in a downward direction. Keep the wrist locked to avoid arcing of line. FIG. 6. DIRECTION OF PENCIL IN SKETCHING VERTICAL LINE IS FROM TOP TO BOTTOM
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 7 of 18
•
•
Angled lines should be sketched by moving the hand and pencil from the left to the right and angling upward or downward. Rotating the paper so lines are horizontal or vertical is also a good practice. Avoid rotating your wrist, as this will cause the line to arc. STEP 1 STEP 2 STEP 3 Arcs and circles should be sketched by A. SKETCHING THE CIRCLE WITHIN A SQUARE creating horizontal and vertical center lines at the center point of the arc or circle. Next, estimate the radius of the arc or circle on each center line and form a box with lines parallel to the center lines. Now start at the top of the box and create four arcs moving the pencil left to right and rotating STEP 1 STEP 2 STEP 3 the paper each time. B. MARKING OFF THE LENGTH OF RADIUS ON ALL LINES FIG. 7. SKETCHING ARCS AND CIRCLES
R=RADIUS ON PAPER STRIP FOR LARGE CIRCLES A. LARGE CIRCLE
PAPER TRAMMEL MARKED WITH MAJOR (R2) & MINOR (R1) RADII B. ELLIPSE
FIG. 8. LARGE CIRCLES, LARGE ARCS AND ELLIPSES ARE EASILY SKETCHED WITH THE AID OF A STRIP OF PAPER
D. TYPES OF SKETCHES 1. Single-view
FIG. 9. TYPICAL ONE-VIEW DRAWINGS. THICKNESS SHOWN.
2. Multiview
FIG. 10 TYPICAL MULTIVIEW DRAWING
Performing Drawing Fundamentals JZGMSAT TESDA IV
3. Pictorials
FIG. 11. TYPICAL PICTORIAL DRAWING
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 8 of 18
E. CONCEPTS AND PRINCIPLES UNDERLYING MULTIVIEW, ISOMETRIC, OBLIQUE, AND PICTORIAL SKETCHING.
A multiview sketch shows different views of an object as seen from different positions and arranged in a standard order.
Pictorial sketches show height, width and depth of an object in one view.
The three basic types of pictorials are isometric, oblique, and perspective.
Concepts in Isometric Drawing 1. In an isometric sketch the three axes are equally spaced 120° apart. The prefix "iso" means equal. 2. The isometric axes are most often positioned so that the receding lines are 30° off the horizontal. Other positions are possible depending on what surfaces of the object are being emphasized. 3. Circular shapes will typically appear as ellipses in isometric sketches. Ellipses must be oriented according to the plane in which they appear. 4. Lines parallel to the isometric axes are called "isometric lines". You can measure along these lines. 5. Lines that are not parallel to the isometric axes are called "non-isometric lines". You cannot measure along these lines. 6. A standard angle measuring device such as a protractor cannot be used to measure angles in isometric. Angles are drawn by locating their end points. Concepts in Oblique Sketching: 1. The front view is normal to the viewer's line of sight in an oblique sketch. 2. A circle drawn on the frontal plane will appear as a circle. A curve drawn on the frontal plane will appear true shape. 3. Circles and curves appearing on the side and top planes will be distorted. 4. Receding edges can be sketched at any angle except vertical or horizontal but are usually drawn at an angle of 30°, 45° or 60°. 5. The long side of an object should be shown in the frontal plane to lessen distortion. 6. Cavalier oblique pictorials are drawn or sketched at full depth. Cabinet oblique pictorials are drawn or sketched at a reduced depth (usually half).
A
B
C
GIVEN OBJECT
FIG. 12. CONCEPTS IN DEVELOPING OBLIQUE DRAWING.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 9 of 18
Concepts in Perspective Sketching 1. The most common types of perspective drawings are one-point perspective and twopoint perspective. 2. A perspective sketch is the most realistic of the pictorial sketches because it appears the most natural. Features that are farther from the observer appear shorter than features closer to the observer. 3. The receding axes converge at the vanishing point and are not parallel as they are in isometric and oblique drawings. TO VANISHING POINT DRAFTING STATION
FIG. 12. PERSPECTIVE SKETCHES Concepts in Multiview Sketching 1. Choose an appropriate number of views to fully describe the shape of the object. 2. If an object can be described with only two dimensions, a one-view drawing may be sufficient. Two, three or more views may be necessary to fully describe the shape of more complicated objects.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 10 of 18
SELF- CHECK NO. 1 Check your mastery in sketching by completing the tasks below.
1. Draw straight lines from point A to point B in freehand drawing.
A
B
A
B
A
B
B
A
2. Sketch circles with a diameter of:
a. 25mm
b. 50mm
Performing Drawing Fundamentals JZGMSAT TESDA IV
c. 30mm
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 11 of 18
JOB SHEET NO. 1 Sketching an Isometric Drawing A. Objectives: After completing the activity you should be able to: 1. Sketch an isometric drawing; 2. Use correct weights of lines; and, 3. Produce properly drawn isometric sketch. B. Tool and Materials: White bond paper Eraser Drawing pencil C. Procedure 1. Choose the orientation; Make sure the front view is along the left side of the isometric drawing. The length of the object should be projected back at 330 degrees. 2. Sketch the overall block that will represent the isometric drawing. Do your best to align the drawing in the middle of the sheet. (do not allow portions of the drawing to be cut off)
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 12 of 18
3. Add construction line details (you may make mistakes) Details consist of circles, arcs, holes, angled lines, or any other lines that represent unique features in the object. (details should be sketched using 4H lead)
4. Darken visible lines. Using your 2H lead (for finished drawings) darken the edges of your object to make them stand out to the viewer.
NOTE: There is no hidden or center lines in isometric detail drawings, as they are utilized to show realistic pictorial view of the object.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 13 of 18
JOB SHEET NO. 2 Sketching a Multiview Drawing A. Objectives: After completing the activity you should be able to: 1. Sketch an multiview drawing; 2. Use correct weights of lines; and, 3. Produce properly sketch multiview drawing. B. Tool and Materials: White bond paper Eraser Drawing pencil C. Procedure Steps In Sketching A Multiview Drawing: 1. Choose the orientation; which side of the object should be designated as the front, top and right side. The front view is typically the view with the most detail.
2. Sketch the overall blocks that will represent the three views. When you have determined the overall dimensions, the Spacing Formula should be used to determine the placement of your three views.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 14 of 18
3. Add construction line details (you may make mistakes) Details consist of circles, arcs, holes, angled lines, or any other lines that represent unique features in the object. (details should be sketched using 4H lead).
4. Darken visible lines. Using your 2H lead (for finished drawings) darken the edges of your object to make them stand out to the viewer. 5. Darken hidden and center lines. Continue darkening details by adding these lines to the finished project.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 15 of 18
JOB SHEET NO. 3 Sketching Circles A. Objectives: After completing the activity you should be able to: 1. Sketch an isometric drawing; 2. Use correct weights of lines; and, 3. Produce properly drawn isometric sketch. B. Tool and Materials: White bond paper Eraser Drawing pencil C. Guidelines for sketching circles 1. Create horizontal and vertical center line lines at the center point of the arc or circle.
2. Estimate the radius of the arc or circle on each center line and form a box with lines parallel to the center lines.
3. Now start at the top of the box and create four arcs moving the pencil left to right and rotating the paper each time.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 16 of 18
ANSWER KEY NO. 1 Check your answer with the answer key below. If you fail to get it right, refer back to corresponding resources until you make it perfect.
1.
A
B
A
B
A
B
B
A
2.
a. 25mm
b. 50mm
Performing Drawing Fundamentals JZGMSAT TESDA IV
c. 30mm
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 17 of 18
RECORD OF COMPETENCE Below are your assessment ratings:
ASSESSMENT /PERFORMANCE CRITERIA
YES
NO
1. Concepts and principles underlying multiview and pictorial sketches are identified 2. Multiview and pictorial technical sketches are performed in accordance to drawing standards
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 18 of 18
SKETCHING
This is the first of the modular series produced by the Jacobo Z. Gonzales Memorial School of Arts and Trades – Technical Education and Skills Development Authority Region IV-A
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 1 of 18
TABLE OF CONTENTS
Content
Page Number
I.
LEARNING GUIDE OVERVIEW …………………………………... …….. 3
II.
HOW TO USE THIS GUIDE ……………………………………………….. 4
III.
LEARNING ACTIVITIES ……………………………………………………. 5
IV.
INFORMATION SHEET A. FORMS OF SKETCHES ………………………………………………. 6 B. TOOLS AND MATERIALS FOR SKETCHING ………………………. 7 C. TECHNIQUES FOR SKETCHING…………………………………….. 7 D. TYPES OF SKETCHES……………………………………………….. 8 E. CONCEPTS AND PRINCIPLES UNDERLYING MULTIVIEW, ISOMETRIC, OBLIQUE, AND PICTORIAL SKETCHING.………….. 9
V.
SELF CHECK ………………………………………………………………... 11
VI.
JOB SHEET 1. SKETCHING AN ISOMETRIC DRAWING ……………..……12 2. SKETCHING A MULTIVIEW DRAWING ……...……………. 14 3. SKETCHING CIRCLES……………………………………….. 17
VII.
ANSWER KEY ………………………………………………………………. 17
VIII.
RECORD OF COMPETENCE …………………………………….………. 18
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 2 of 18
LEARNING GUIDE OVERVIEW Sketching is one of the primary means of graphic communication. The ability to sketch is an essential tool in conveying original ideas from the engineer to the designer and from the designer to the drafter. As instrument drawing becomes less prevalent in industry, the ability to create accurate technical sketches becomes more important. In this learning material, the students should be able to communicate technical information through different types of sketches. This will cover the purpose of sketching, materials needed for sketching, techniques for sketching, the types of sketches, and differences between isometric, oblique and perspective and multiview sketches Competencies will be demonstrated by completing the job sheets and the unit test with a minimum score of 75 percent.
OBJECTIVES
When you have successfully completed the learning activities in this material, you will be able to: 1. Identify the concepts related to sketching; 2. Explain the concepts related to sketching multiview and pictorials; and, 3. Make multiview, isometric, oblique, and perspective sketches.
CONTENTS
This learning material includes the following: 1. Forms of Sketches 2. Materials for Sketches 3. Techniques for Sketching 4. Types of Sketches 5. Concepts and Principles Underlying Multiview, Isometric, Oblique, and Pictorial Sketching
PRE-REQUISITES
The completion of this learning material requires you to have a basic understanding of:
If you are unfamiliar with any of the above concepts, work on________ before working on this learning guide.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 3 of 18
HOW TO USE THIS LEARNING GUIDE This Learning Guide will lead you through a series of activities which will require you to work at your own pace. These activities will ask you to complete associated learning and practice activities in order to gain the knowledge and skills you need to achieve the learning objectives stated earlier. Refer to Learning Activity Page to know the sequence of learning tasks to undergo and the appropriate resources to use in each task. This page will serve as your road map towards the achievement of objectives. Read the information sheets. This will give you an understanding of the work, and why things are done the way they are. Complete the activities as directed in the activity/practice sheets. These will test your knowledge and give you practice of doing the tasks involved. Performance criteria for assessing practical exercise are shown to guide you in undertaking the practical exercises. Always be aware of safety requirements highlighted in this material. Ask for clearance in using some tools and equipment. Should you require some assistance and clarification, consult your trainer or facilitator. They should be available anytime you need them. Answer self-checks found in each section of the learning guide. Do not write anything on this learning guide; provide separate sheets for your answers. Self-checks will let you know how you are going. To know how you fared with self checks, review the answer keys found at the end of the learning guide. When you had completed all the tasks required in this learning guide, an assessment exercise will be given to evaluate if you are already competent with the specified learning outcomes in and ready for the next task. .If you feel ready for the assessment, consult the facilitator. A record of competency is provided on the last page to reflect how much of the required assessment criteria have been met. You may already have some or most of the knowledge and skills covered in this learner’s guide. Talk to your trainer about having them formally recognized. If you have qualification or certificate of competence from previous training, show it to your trainer. If the skills you acquired are still current and relevant to the unit of competency they may become part of the evidence you can present for Recognition of Prior Learning (RPL). If you are not sure about the accuracy of your skills, discuss it with your trainer.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 4 of 18
LEARNING ACTIVITIES In order to accomplish the objectives stated in this leaning guide, you must perform the learning steps below. Beside each step are the resources or special instructions you will use to accomplish the corresponding activity. RESOURCES/SPECIFIC INSTRUCTIONS
LEARNING STEPS
1. Student will ask the instructor of
1.
Instructor will provide the learning materials in Sketching
the materials to be used 2. Read: Information Sheet No. 1
2.
Information sheet No 1: Sketching
3. Answer: Self Check
3.
Self Check: Sketching
4. Perform: Job Sheet No. 1
4.
Job Sheet No. 1: Sketching an Isometric Drawing
5. Perform: Job Sheet No. 2
5.
Job Sheet No. 2: Sketching a Multiview Drawing
6. Perform: Job Sheet No. 3
6.
Job Sheet No. 3: Sketching Circles
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 5 of 18
INFORMATION SHEET NO: 1
SKETCHING Sketching is a freehand drawing process that allows detailers, designers, engineers, architects, technicians and tradespersons to record their ideas quickly on paper without the use of tools. Once they have recorded their ideas, they can revise and refine their sketches for presentation to their supervisors or clients. Sketching is also helpful in preliminary planning of a drawing or layout before using tools.
A. FORMS OF SKETCHES 1. Design sketches - Design sketches are rough sketches that are used to quickly capture an idea. They tend to have less detail, structure and restrictions than freehand or technical illustrations.
FIG. 1. A ROUGH SKETCH WITH NOTES ABOUT IMPORTANT FEATURES. 2. Freehand technical sketches - Freehand technical sketches can be multiview or pictorial sketches. This type of sketch usually includes more detail and structure than design sketches. They also typically include dimensions (see Fig. 2). 3. Technical illustrations - Technical illustrations include more detail, structure, and restrictions than other types of sketches. The objective here is to create a sketch that looks as close to the final object as possible.
FIG. 2. MULTIVIEW SKETCH
FIG. 3. A SKETCH CAN SHAPE A FUTURISTIC DESIGN.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 6 of 18
B. TOOLS AND MATERIALS FOR SKETCHING Paper You can use a plain paper for sketching. If you need to refine the sketch, use tracing paper. Control proportions while sketching by using cross-section paper, also called graph paper or squared paper. There are specially ruled graph papers for particular kinds of drawing such as isometric and perspective. You can sketch on any convenient size of paper. However, A4 size drawing paper will only be allowed for this course as an official drawing paper. Pencils and Eraser Most drafters like to use soft lead pencils (grades F, H or HB), properly sharpened. They also use an eraser that is good for soft leads, such as a plastic eraser or a kneaded-rubber eraser. Use drafter’s pencil sharpener to remove the wooden part of the pencil from the lead. Make the lead of the pencil sharp by using sandpaper block or pad. Four types of points are used for sketching: sharp, near-sharp, near-dull, and dull. The points should make the following kinds: • Sharp point—a thin black line for center, dimension, and extension lines • Near-sharp point—visible or object lines • Near-dull point—cutting-plane line and border lines • Dull point—construction lines
FIG. 4 FOUR CONVENIENT PENCIL POINTS FOR SKETCHING
C. TECHNIQUES FOR SKETCHING •
Horizontal lines should be sketched by moving the hand and pencil from the left to the right if right handed. Avoid rotating your wrist, as this will cause the line to arc. FIG. 5. DIRECTION OF PENCIL IN SKETCHING HORIZONTAL LINE IS FROM LEFT TO RIGHT
•
Vertical lines should be sketched by moving the hand and pencil from the top in a downward direction. Keep the wrist locked to avoid arcing of line. FIG. 6. DIRECTION OF PENCIL IN SKETCHING VERTICAL LINE IS FROM TOP TO BOTTOM
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 7 of 18
•
•
Angled lines should be sketched by moving the hand and pencil from the left to the right and angling upward or downward. Rotating the paper so lines are horizontal or vertical is also a good practice. Avoid rotating your wrist, as this will cause the line to arc. STEP 1 STEP 2 STEP 3 Arcs and circles should be sketched by A. SKETCHING THE CIRCLE WITHIN A SQUARE creating horizontal and vertical center lines at the center point of the arc or circle. Next, estimate the radius of the arc or circle on each center line and form a box with lines parallel to the center lines. Now start at the top of the box and create four arcs moving the pencil left to right and rotating STEP 1 STEP 2 STEP 3 the paper each time. B. MARKING OFF THE LENGTH OF RADIUS ON ALL LINES FIG. 7. SKETCHING ARCS AND CIRCLES
R=RADIUS ON PAPER STRIP FOR LARGE CIRCLES A. LARGE CIRCLE
PAPER TRAMMEL MARKED WITH MAJOR (R2) & MINOR (R1) RADII B. ELLIPSE
FIG. 8. LARGE CIRCLES, LARGE ARCS AND ELLIPSES ARE EASILY SKETCHED WITH THE AID OF A STRIP OF PAPER
D. TYPES OF SKETCHES 1. Single-view
FIG. 9. TYPICAL ONE-VIEW DRAWINGS. THICKNESS SHOWN.
2. Multiview
FIG. 10 TYPICAL MULTIVIEW DRAWING
Performing Drawing Fundamentals JZGMSAT TESDA IV
3. Pictorials
FIG. 11. TYPICAL PICTORIAL DRAWING
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 8 of 18
E. CONCEPTS AND PRINCIPLES UNDERLYING MULTIVIEW, ISOMETRIC, OBLIQUE, AND PICTORIAL SKETCHING.
A multiview sketch shows different views of an object as seen from different positions and arranged in a standard order.
Pictorial sketches show height, width and depth of an object in one view.
The three basic types of pictorials are isometric, oblique, and perspective.
Concepts in Isometric Drawing 1. In an isometric sketch the three axes are equally spaced 120° apart. The prefix "iso" means equal. 2. The isometric axes are most often positioned so that the receding lines are 30° off the horizontal. Other positions are possible depending on what surfaces of the object are being emphasized. 3. Circular shapes will typically appear as ellipses in isometric sketches. Ellipses must be oriented according to the plane in which they appear. 4. Lines parallel to the isometric axes are called "isometric lines". You can measure along these lines. 5. Lines that are not parallel to the isometric axes are called "non-isometric lines". You cannot measure along these lines. 6. A standard angle measuring device such as a protractor cannot be used to measure angles in isometric. Angles are drawn by locating their end points. Concepts in Oblique Sketching: 1. The front view is normal to the viewer's line of sight in an oblique sketch. 2. A circle drawn on the frontal plane will appear as a circle. A curve drawn on the frontal plane will appear true shape. 3. Circles and curves appearing on the side and top planes will be distorted. 4. Receding edges can be sketched at any angle except vertical or horizontal but are usually drawn at an angle of 30°, 45° or 60°. 5. The long side of an object should be shown in the frontal plane to lessen distortion. 6. Cavalier oblique pictorials are drawn or sketched at full depth. Cabinet oblique pictorials are drawn or sketched at a reduced depth (usually half).
A
B
C
GIVEN OBJECT
FIG. 12. CONCEPTS IN DEVELOPING OBLIQUE DRAWING.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 9 of 18
Concepts in Perspective Sketching 1. The most common types of perspective drawings are one-point perspective and twopoint perspective. 2. A perspective sketch is the most realistic of the pictorial sketches because it appears the most natural. Features that are farther from the observer appear shorter than features closer to the observer. 3. The receding axes converge at the vanishing point and are not parallel as they are in isometric and oblique drawings. TO VANISHING POINT DRAFTING STATION
FIG. 12. PERSPECTIVE SKETCHES Concepts in Multiview Sketching 1. Choose an appropriate number of views to fully describe the shape of the object. 2. If an object can be described with only two dimensions, a one-view drawing may be sufficient. Two, three or more views may be necessary to fully describe the shape of more complicated objects.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 10 of 18
SELF- CHECK NO. 1 Check your mastery in sketching by completing the tasks below.
1. Draw straight lines from point A to point B in freehand drawing.
A
B
A
B
A
B
B
A
2. Sketch circles with a diameter of:
a. 25mm
b. 50mm
Performing Drawing Fundamentals JZGMSAT TESDA IV
c. 30mm
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 11 of 18
JOB SHEET NO. 1 Sketching an Isometric Drawing A. Objectives: After completing the activity you should be able to: 1. Sketch an isometric drawing; 2. Use correct weights of lines; and, 3. Produce properly drawn isometric sketch. B. Tool and Materials: White bond paper Eraser Drawing pencil C. Procedure 1. Choose the orientation; Make sure the front view is along the left side of the isometric drawing. The length of the object should be projected back at 330 degrees. 2. Sketch the overall block that will represent the isometric drawing. Do your best to align the drawing in the middle of the sheet. (do not allow portions of the drawing to be cut off)
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 12 of 18
3. Add construction line details (you may make mistakes) Details consist of circles, arcs, holes, angled lines, or any other lines that represent unique features in the object. (details should be sketched using 4H lead)
4. Darken visible lines. Using your 2H lead (for finished drawings) darken the edges of your object to make them stand out to the viewer.
NOTE: There is no hidden or center lines in isometric detail drawings, as they are utilized to show realistic pictorial view of the object.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 13 of 18
JOB SHEET NO. 2 Sketching a Multiview Drawing A. Objectives: After completing the activity you should be able to: 1. Sketch an multiview drawing; 2. Use correct weights of lines; and, 3. Produce properly sketch multiview drawing. B. Tool and Materials: White bond paper Eraser Drawing pencil C. Procedure Steps In Sketching A Multiview Drawing: 1. Choose the orientation; which side of the object should be designated as the front, top and right side. The front view is typically the view with the most detail.
2. Sketch the overall blocks that will represent the three views. When you have determined the overall dimensions, the Spacing Formula should be used to determine the placement of your three views.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 14 of 18
3. Add construction line details (you may make mistakes) Details consist of circles, arcs, holes, angled lines, or any other lines that represent unique features in the object. (details should be sketched using 4H lead).
4. Darken visible lines. Using your 2H lead (for finished drawings) darken the edges of your object to make them stand out to the viewer. 5. Darken hidden and center lines. Continue darkening details by adding these lines to the finished project.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 15 of 18
JOB SHEET NO. 3 Sketching Circles A. Objectives: After completing the activity you should be able to: 1. Sketch an isometric drawing; 2. Use correct weights of lines; and, 3. Produce properly drawn isometric sketch. B. Tool and Materials: White bond paper Eraser Drawing pencil C. Guidelines for sketching circles 1. Create horizontal and vertical center line lines at the center point of the arc or circle.
2. Estimate the radius of the arc or circle on each center line and form a box with lines parallel to the center lines.
3. Now start at the top of the box and create four arcs moving the pencil left to right and rotating the paper each time.
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 16 of 18
ANSWER KEY NO. 1 Check your answer with the answer key below. If you fail to get it right, refer back to corresponding resources until you make it perfect.
1.
A
B
A
B
A
B
B
A
2.
a. 25mm
b. 50mm
Performing Drawing Fundamentals JZGMSAT TESDA IV
c. 30mm
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 17 of 18
RECORD OF COMPETENCE Below are your assessment ratings:
ASSESSMENT /PERFORMANCE CRITERIA
YES
NO
1. Concepts and principles underlying multiview and pictorial sketches are identified 2. Multiview and pictorial technical sketches are performed in accordance to drawing standards
Performing Drawing Fundamentals JZGMSAT TESDA IV
Version No.: 1 Date: May 12, 2006 By: Glenn F. Salandanan Page 18 of 18
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