Engineering Graphics & Technology. NQF Level 2. Sparrow Consulting LECTURER S GUIDE TVET FIRST

Transcription

1 Engineering Graphics & Technology NQF Level 2 Sparrow Consulting LECTURER S GUIDE TVET FIRST

2 Engineering Graphics & Technology NQF Level 2 Lecturer s Guide M Conradie

3 Engineering Graphics & Technology NQF Level 2 Lecturer s Guide Sparrow Consulting, 2010 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying, recording, or otherwise, without the prior written permission of the copyright holder or in accordance with the provisions of the Copyright Act, 1978 [as amended]. Any person who does any unauthorised act in relation to this publication may be liable for criminal prosecution and civil claims for damages. First published in 2010 by Troupant Publishers [Pty] Ltd PO Box 4532 Northcliff 2115 Distributed by Macmillan South Africa [Pty] Ltd ISBN: It is illegal to photocopy any page of this book without written permission from the publisher. While every effort has been made to ensure the information published in this work is accurate, the authors, editors, publisher and printers take no responsibility for any loss or damage suffered by any person as a result of reliance upon the information contained herein. The publisher respectfully advises readers to obtain professional advice concerning the content. While every effort has been made to trace the copyright holders and obtain copyright permission from them, in some cases this has proved impossible due to logistic and time constraints. Any copyright holder who becomes aware of infringement on our side is invited to contact the publisher. Note: Any reference to Further Education and Training (FET) in this book should be taken to mean Technical and Vocational Education and Training (TVET). To order any of these books, contact Macmillan Customer Services at: Tel: (011) Fax: (011) customerservices@macmillan.co.za

4 Contents Topic 1: Fundamentals of Engineering Graphics and Technology... 1 Module 1: Using drawing instruments and equipment...1 Unit 1.1: Identify and use appropriate drawing instruments and equipment... 1 Module 2: Use drawing conventions, line types and lettering Unit 2.1: Identify, explain and draw to illustrate the purpose of different types of lines used in engineering graphics and technology Unit 2.2: Explain and illustrate different sizes of lettering and numbering applications Unit 2.3: Explain and draw to illustrate the purpose of engineering graphics and technology (mechanical) drawing conventions Topic 2: Freehand drawings in engineering Module 3: Explain and use freehand drawing techniques Unit 3.1: Explain and demonstrate the use of freehand drawing techniques Module 4: Reproduce freehand drawings Unit 4.1: Reproduce freehand drawings of two-dimensional engineering components in proportion Unit 4.2: Reproduce freehand drawings of two-dimensional engineering components to scale Topic 3: Geometric constructions Module 5: Use construction procedures to solve geometric construction line and shape applications Unit 5.1: Explain basic concepts related to simple line applications in geometrical constructions Unit 5.2: Draw simple line applications in geometrical constructions Unit 5.3: Explain basic concepts related to geometrical shape applications in geometrical constructions Unit 5.4: Draw geometrical shape applications in geometrical constructions Module 6: Reproduce drawings of engineering components Unit 6.1: Describe types of scales used to produce engineering drawings Unit 6.2: Reproduce a drawing according to a selected scale illustrating a single view of an engineering component Unit 6.3: Draw a two-dimensional view of engineering components according to a selected scale Topic 4: Loci Module 7: Draw and interpret applications of loci Unit 7.1: Explain and draw the application of involutes of various geometrical shapes Unit 7.2: Explain and draw cycloids and epicycloids Unit 7.3: Explain and construct an Archimedean spiral Unit 7.4: Explain and construct a helix Topic 5: Principles of orthographic projection Module 8: Draw and interpret orthographic projections Unit 8.1 Draw to scale primary views of prisms and pyramids in first-angle and third-angle orthographic projection Unit 8.2 Interpret the principles of visualisation in first-angle and third-angle orthographic projection Unit 8.3. Explain the principles of first-angle and third-angle orthographic projection Unit 8.4 Draw to scale 1:1, 1:2, 1:5, 1:10 and 2:1 primary views of single engineering components in first-angle and third-angle orthographic projection Unit 8.5: Draw to scale primary views of prisms and pyramids in first- and third-angle orthographic projection Topic 6: Pictorial drawing Module 9: Construct an oblique projection Unit 9.1 Interpret and draw an oblique projection of a single engineering component Module 10: Explain and draw one-point and two-point perspective views Unit 10.1: Describe terminology related to perspective drawings Unit 10.2: Draw a one-point and a two-point perspective view of a single engineering component using the measuring point method... 90

5 Topic 1: Fundamentals of engineering graphics and technology Module 1: Using drawing instruments and equipment The following step-by-step planning will assist you in preparing your lessons. You may also modify the learning activities provided in the Student s Book for this module to suit your requirements. Subject Outcome 1.1 Use drawing instruments and equipment. Learning Outcomes Is the student able to Identify and use appropriate drawing instruments and equipment. Units Unit 1.1: Identify and use appropriate drawing instruments and equipment. Assessment activities Assessment activities Summative assessment Unit 1.1: Identify and use appropriate drawing instruments and equipment This unit deals with drawing instruments and equipment. Review the unit in the Student s Book carefully. Complete your lesson preparation form. Assessment activity 1.1 Individual activity Students must complete the following tasks on their own. Make sure in advance that all of the students have the correct equipment to complete the task correctly. Students will need: Drawing board. A3 drawing sheets. Masking tape or clips. Clutch pencil and eraser. T-square and set squares. Each student has to do the following. 1. Set up a sheet of paper on their drawing board. 2. Draw vertical parallel lines using their T-square and triangles. 3. Draw vertical parallel lines using their T-square and set squares. 4. Draw parallel lines at an angle to the horizontal. 5. Draw a line parallel to a given line. 6. Draw a line perpendicular to a given line. 7. Draw angles of 15 and Draw a rectangle with T-square and triangle. Peer assessment: The student s work will be assessed by a fellow student according to the following rubric. Criteria Not yet competent Competent The student correctly set up a piece of paper on the drawing board. 1. The student correctly drew vertical parallel lines using a T-square and triangles. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Topic 1: Fundamentals of Engineering Graphics and Technology 1

6 Criteria Not yet competent Competent Place the T-square against the edge of the drawing board. There must be no gaps, otherwise the paper will not be set up correctly and it will be impossible to draw accurate horizontal. Allow the paper to rest on the T-square. Check that the paper rests properly on the T-square and that there are no gaps between the T-square and the paper, or between the T-square and the side of the drawing board. Fix the paper with clips or masking tape. 2. The student correctly drew vertical parallel lines using his/her T-square and set squares. 3. The student correctly drew parallel lines at an angle with the horizontal. 4. The student correctly drew a line parallel to a given line. Draw line EF and point P as shown in the figure on page 13 of the Student Book, using your T-square. EF serves as the given line. Point P can be any point. Place set square A with one edge coinciding with line EF. Take set square B and place one of its edges in contact with the bottom edge of set square A. Holding set square B firmly with the left hand, slide set square A to the right or to the left until its edge reaches point P. Draw line MN to pass through point P. 5. The student correctly drew a line perpendicular to a given line. Place the set square vertically on the line EF, so that the bottom edge is on the line. From the apex of the set square, draw a line down the set square to meet the line EF. Draw line EF and point D, as shown in the figure below. Point D can be any point. EF serves as the given line. Place the longest side of set square A so that it coincides with line EF. Place the other set square in the position of set square B. Holding B with the left hand, place set square A in position C, so that the longest side passes through point D. Beginning (0-39%) Developing (40-49%) 2 Topic 1: Fundamentals of Engineering Graphics and Technology Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%)

7 Criteria Not yet competent Competent Draw a line through point D perpendicular to EF. 6. The student correctly drew angles of 15 and The student correctly drew a rectangle with T-square and triangle. Draw sides AB and DC horizontal and parallel, using the T-square as shown in the figure below. Place the set square on the T-square in position E and draw the vertical line DA. Move the set square on the T-square to position F and draw the vertical line BC. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Assessment activity 1.2 Individual activity Make sure in advance that all of the students have the correct equipment to complete the tasks correctly. Students will need: Drawing board. A3 paper. Pencil and eraser. Compass. Ruler. Protractor. Students must complete the following task on their own. 1. Double check these measurements before marking the student s answers. (a) 35 (b) 70 (c) 130 (d) 90 (e) 15 (f) 280 (g) 105 (h) Double check these measurements before marking the student s answers. a) 30 b) 20 c) 90 d) 50 e) 90 f) 110 g) Students will have to physically check each other s work to determine the correctness of each activity. Peer assessment: The student s work will be assessed by another student according to the following rubric. Criteria Not yet competent Competent The student correctly used a compass to draw a circle of radius 5.5 cm. The student correctly drew a diameter and labelled it PQ. The student correctly drew a triangle PQR where R is on the semicircle. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Topic 1: Fundamentals of Engineering Graphics and Technology 3

8 Criteria Not yet competent Competent The student correctly used a protractor to measure the size of angle PRQ. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Assessment activity 1.3 Individual activity Make sure in advance that all of the students have the correct equipment to complete the tasks correctly. Students will need: A scale ruler. Sheet of paper and a pencil. Normal metric ruler. You drew a line that is 15 units long to a scale of 1:500. This means that each millimetre you measure would be equal to 500 millimetres on the original object. Your 15 units long scale object would thus measure 15 mm 500 = 7500 mm = 7,5 m. Assessment activity 1.4 Working in pairs Students will need: A tape measure or ruler. Paper and a pencil. There are no specific answers as it will depend on the size of each individual item. Therefore, students have to check each other s work to determine how accurate their measurements were. Assessment activity 1. 5 Individual activity Students will need: Compass. A3 paper. Drawing board. Masking tape. Divider. Ruler. Students will have to physically check each other s work to determine the correctness of each activity. Peer assessment: The student s work will be assessed by another student according to the following rubric. Criteria Not yet competent Competent 1. The student correctly used a compass to draw a circle of radius 4 cm. Use a ruler to set the distance from the point of the compass to the pencil s lead at 4 cm. Place the point of the compass at the centre of the circle. Draw the circle by turning the compass through The student correctly used a compass to construct a hexagon with radius 6 cm. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) 4 Topic 1: Fundamentals of Engineering Graphics and Technology

9 Criteria Not yet competent Competent Draw a circle to the size of the hexagon required (6 cm radius). Set dividers or a compass to the radius of the circle. Use this length to step off the circle into six equal parts. Draw lines to connect the points on the circle. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Assessment activity 1.6 Individual and pair activity Students will need: Various drafting stencils. Paper. A sharp pencil. 1. Make sure that you have something to give to the winner, for example, a specific stencil he/she will need during his/her studies, a drawing pencil or a slab of chocolate. 2. Students will need: Poster board. Koki pens. Glue. Pictures/photos of the instruments. The instruments discussed in this unit and their uses include: Instrument Uses How it should be used Drawing board Drawing sheets Clutch pencil Eraser Used to hold the paper firmly in place when drawing. It includes a T-square and ruler which are used to draw lines. Used to draw on. Used for general writing and drawing, as well as technical writing. State the applications of the following lead thicknesses: 0,3 mm 0,5 mm 0,7 mm. Used to remove graphite from the paper. The board is lifted at an angle to make it easier and more comfortable to draw on. How to use a pencil to draw lines: Hold the pencil comfortably and naturally. Grip the pencil lightly. Slightly slant or tilt the pencil, about 60, in the direction in which the line is being drawn. Pull the pencil at the same inclination for the full length of the line. Do not push it. Rub the eraser over the markings that you want to remove; stroke it in one direction only. T-square Useful for drawing horizontal lines. Place a sheet of paper on your drawing board. Secure the paper to the board by taping it at the four corners. Hold the T-square in the correct position and draw a line from left to right. Set square Most useful drawing board tool as all lines but horizontal ones can be drawn with these triangles. Use with a T-square. Draw a vertical line from the bottom of the triangle, moving up towards the apex. Draw a sloping line along the hypotenuse of the triangle by going from the apex to the base. Topic 1: Fundamentals of Engineering Graphics and Technology 5

10 Scale ruler Compass and divider Used to draw according to a certain scale. OR A three-sided ruler used to draw and measure scale drawings easily. Used to draw circles and arcs. Decide which scale to use. Find this scale on the scale ruler. Find the 0 marking on the ruler. Place the ruler on the paper, with the 0 marking at the point where you want the line to start. Draw along the ruler from 0 up to the mark that represents the length of the object. The measurement might contain decimal places, in which case you will have to calculate how many units each small mark on the ruler represents. How to use a compass to draw an arc or circle: Make sure that the hinge at the top of the compass is tightened so that it does not slip. Place a sharp, soft compass lead (F or HB) in the drafting lead arm so that the circle can be drawn with dark object lines. Align the pencil lead with the compass s needle. Tighten the hold for the pencil so it does not slip. Adjust the width, or spread, of the compass. Draw a light cross where you want the centre of the circle to be. Place the compass needle at the centre of the circle where the two centre lines intersect. Rotate the compass to draw the line by twisting your thumb and forefinger. Make sure that the outer edge of the compass leans in the direction of the movement during rotation. How to use a divider: Place the two points of the divider on opposite ends of the line or distance that you want to measure. Place a ruler next to the point. Read the distance from the ruler. Protractor Used to measure angles and circles. Place the protractor over the angle. Line up the vertex on the centre line at the bottom. The small circle at the centre of the protractor must be put directly above the point (vertex) where the two lines of the angle meet. Make sure the bottom line of the angle is lined up straight with the zero line of the protractor. The other line will point to a number on the protractor. If the angle is acute, read the smaller number. If the angle is obtuse, read the larger number. Stencils or templates A drafting stencil consists of a flat piece of plastic with standard symbols cut in it that is used as a template to create neat and identical letters, symbols, shapes or patterns when these are to be drawn repeatedly. Make sure that you hold the template down firmly to keep it from slipping out of position. Figures from the template must always be drawn with the correct line weight on the first setting, as it is difficult to reset the template in the exact position. To draw a circle: Lay out centre lines on the drawing where you want to draw the circle. Place the correct circle opening over the centre line so that the quadrant lines on the template coincide with the centre lines on the paper. Draw the circle using the sharp, conical point on the pencil. 6 Topic 1: Fundamentals of Engineering Graphics and Technology

11 Assessment: The student s poster will be assessed by the lecturer according to the following rubric. Criteria Not yet competent Competent Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) The student was able to correctly name each instrument and inserted pictures of all instruments. The student was able to correctly explain the different uses of each instrument and its different types. The student was able to identify the specific types of instruments that he/ she will need. The student was able to supply some interesting information about the instruments. The student included examples of the use of the different instruments. The student included graphics/photos that are related to the topic and make it easier to understand. The poster is attractive in terms of design, layout and neatness. It is balanced, uncluttered and white space is adequate. Summative assessment (p24 in the Student s Book) Theoretical assessment [10] Complete the following table by naming the instrument and explaining its use. Instrument Name Use Kneaded erasers These erasers remove graphite and charcoal by absorbing them. Drawing board A drawing board is a very specific type of instrument for creating engineering drawings. The T-squares and rulers can hook onto the board and can be moved forward and backward as well as up and down. The board is lifted at an angle to make it easier and more comfortable to draw and reach all the spaces on the drawing sheet, as it is quite big. Topic 1: Fundamentals of Engineering Graphics and Technology 7

12 Instrument Name Use Semi-circular protractor A protractor is a circular or semi-circular object that is used to measure angles and circles. These measurements are usually expressed in degrees. A protractor has two sets of numbers that run in opposite directions. Which set you use will depend on the angle you are measuring or drawing. Divider Dividers are used to compare sizes, divide line segments and measure distances on drawings. Drafting stencil Only use drafting templates when you can sacrifice accuracy for speed, for example, circles can be drawn much quicker with a template than with a compass. However, it is important that you use the template properly for it to be effective. Practical assessment [40] Before beginning, make sure that all of the students have the equipment to complete the task correctly. Students will need: A3 paper. Drawing board. Masking tape. Divider. A sharp pencil. An eraser. T-square and set squares. Ruler. Compass or divider. 8 Topic 1: Fundamentals of Engineering Graphics and Technology

13 1. [10] Assessment: The student s drawings will be assessed by the lecturer according to the following checklist. Checklist Secure an A3 paper to your drawing board by taping it at the four corners. [1*] Use your divider to measure 1 cm from the edge of the paper and mark it. [1] Draw the borderline 1 cm from the edge of the paper using your pencil. [1] Draw four squares measuring 10 cm 10 cm on the central part of the paper. Use your T-square and triangle. On the first square, draw vertical lines measuring 1 cm apart. Label it box A. [1] On the second square, draw horizontal lines measuring 1 cm apart. Label it box B. [1] On the third square, draw inclined lines at 30 at a distance of 1 cm apart from each other. Label the [1] third square box C. In the fourth square, draw inclined lines at 45 0 at a distance of 1 cm from each other. Label the last [1] square box D. * A bonus point may be given here. 2. Physically check each student s work to determine the correctness of each drawing. [4 5] /x [4] 4 cm 4 cm 3 cm 3 cm 2 cm 4 cm 2 cm 4 cm 3 cm 5 cm 5 cm 1 cm 1 cm 1,5 cm 1 cm 4 cm 5 cm 4 cm 5 cm 3 cm 3 cm 3 cm 8 cm Topic 1: Fundamentals of Engineering Graphics and Technology 9

14 Assessment: The student s drawings will be assessed by the lecturer according to the following rubric. Criteria Not yet competent Competent Did the student use a T-square, two set squares and a ruler correctly? Did the student draw at least four of the given figures accurately? Did the student use the correct drawing method? Did the student erase lines where necessary? Is the student s work neat? Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) 3. Physically check each student s work to determine the correctness of the drawing. Assess the Student's work according to the following checklist. Outstanding (80-100%) Checklist Was the equipment used correctly? Does the octagon have a radius of 5 cm? Are all eight of the octagon s sides the same length? Was the correct method followed? Is the final drawing neat? 4. Double check these measurements before marking the student s Answers a) 75 b) 90 c) 120 d) 30 e) 289 / Module 2: Use drawing conventions, line types and lettering The following step-by-step planning will assist you in preparing your lesson. You may also modify the learning activities provided in the Student s Book for this module to suit your requirements. Subject Outcome 1.2 Use drawing conventions, line types and lettering. Learning Outcomes Is the student able to Identify, explain and draw to illustrate the purpose of different types of lines used in engineering graphics and technology. Explain and illustrate different sizes of lettering and numbering applications. Explain and draw to illustrate the purpose of engineering graphics and technology (mechanical) drawing conventions. Units Unit 2.1: Identify, explain and draw to illustrate the purpose of different types of lines used in engineering graphics and technology. Unit 2.2: Explain and illustrate different sizes of lettering and numbering applications. Unit 2.3: Explain and draw to illustrate the purpose of engineering graphics and technology (mechanical) drawing conventions. Assessment activities Assessment activity Assessment activity 2.4 Assessment activity 2.5 Summative assessment 10 Topic 1: Fundamentals of Engineering Graphics and Technology

15 Unit 2.1: Identify, explain and draw to illustrate the purpose of different types of lines used in engineering graphics and technology This unit deals with the purpose of different types of lines used in engineering graphics and technology. Review the unit in the Student s Book carefully. Complete your lesson preparation form. Assessment activity 2.1 Pair activity 1. Note: Make sure that you have a copy of the South African National Standards for engineering (mechanical) drawings ready, so you can assist the students if necessary. Students will need: Copies of SANS and SANS SANS Engineering drawings Part 1 General principles 1 Scope 2 Drawing sheets and materials 3 Scales 4 Lines, letters, figures and symbols, and arrowheads 5 Layout of drawings 6 Projection 7 Sections and sectional views 8 Conventional representation of common features 9 Dimensioning and tolerancing 10 Machining and surface texture symbols Part 2: Geometrical tolerancing Section 1: Tolerancing of form, orientation, location and run-out Generalities, definitions, symbols, indications on drawings 1 Scope 2 Normative references 3 Terms and definitions 4 Basic concepts 5 Symbols 6 Tolerance frame 7 Tolerance features 8 Tolerance zones 9 Datums 10 Supplementary indications 11 Theoretically exact dimensions (TED) 12 Restrictive specifications 13 Projected tolerance zone 14 Maximum material requirement 15 Least material requirement 16 Free state condition 17 Interrelationship of geometrical tolerances 18 Definitions of geometrical tolerances Part 2.2: Geometrical tolerancing Datums and datum-systems for geometrical tolerances 1 Scope and field of application 2 References 3 Definitions 4 Establishing datums 5 Application of datums 6 Indication of datums and datum-systems 7 Datum targets 8 Three-plane datum-system 9 Groups of features nominated as datums Topic 1: Fundamentals of Engineering Graphics and Technology 11

16 Part 2.3: Geometrical product specifications (GPS) Geometrical tolerancing Maximum material requirement (MMR), least material requirement (LMR) and reciprocity requirement (RPR) 1 Scope 2 Normative references 3 Terms and definitions 4 Maximum material requirement, MMR and least material requirement, LMR 4.1 General 4.2 Maximum material requirement, MMR 4.3 Least material requirement, LMR 5 Reciprocity requirement, RPR 5.1 General 5.2 Reciprocity requirement and maximum material requirement 5.3 Reciprocity requirement and least material requirement Part 2.4: Geometrical Product Specifications (GPS) Geometrical tolerancing Positional tolerancing 1 Scope 2 Normative reference 3 Definitions 4 Establishment of positional tolerances 4.1 General 4.2 Fundamental requirement 4.3 Theoretically exact dimensions 4.4 Positional tolerances on a complete circle 4.5 Directions of positional tolerances 5 Tolerance combinations Part 2.5: Geometrical tolerancing Fundamental tolerancing principle 1 Scope 2 Field of application 3 References 4 Principle of independency 5 Tolerances 5.1 Dimensional tolerances 5.2 Geometrical tolerances 6 Mutual dependency of size and geometry 6.1 Envelope requirement 6.2 Maximum material principle 7 Application on drawings 7.1 Completeness of drawings 7.2 Designation Part 3: Guidelines for the interpretation and verification methods of geometrical tolerancing 1 Scope and field of application 2 Normative reference 3 Definitions 4 Symbols 5 Establishment of datums 6 Verification principles and methods 7 Verification of straightness 8 Verification of flatness 9 Verification of circularity 10 Verification of cylindricity 11 Verification of profile of any line 12 Verification of profile of any surface 13 Verification of parallelism 14 Verification of perpendicularity 15 Verification of angularity 16 Verification of position 17 Verification of concentricity 18 Verification of coaxiality 19 Verification of symmetry 20 Verification of circular run-out 21 Verification of total run-out 12 Topic 1: Fundamentals of Engineering Graphics and Technology

17 SANS Building drawing practice SECTION 1. SCOPE SECTION 2. GENERAL SECTION 3. CLASSIFICATION OF DRAWINGS 3.1 General 3.2 Types of Drawings Sketch drawings Design drawings Working drawings 3.3 Check List for Working Drawings General Site plans Layout drawings 3.4 Rationalised Working Drawings 3.5 Sectional Titles Act Drawings 3.6 Revisions of Drawings SECTION 4. SIZE OF DRAWING SHEETS 4.1 Standard Sizes 4.2 Folding SECTION 5. LAYOUT OF DRAWING SHEETS 5.1 Layout Filing margins Title panel Information panel 5.2 Key 5.3 Orientation of Plans SECTION 6. SCALES 6.1 General 6.2 Choice of Scale SECTION 7. LINES 7.1 General 7.2 Minimum Thickness 7.3 Density of Lines SECTION 8. ANNOTATION 8.1 Notes 8.2 Lettering 8.3 Spacing 8.4 Scribers SECTION 9. DIMENSIONS 9.1 General 9.2 Dimension Line 9.3 Dimension Figures General Decimal notation Thousands markers Linear dimensions on drawings 9.4 Sequence of Dimensioning 9.5 Tolerances SECTION 10. LEVELS 10.1 General 10.2 Datum Levels 10.3 Levels on Plans 10.4 Levels on Sections and Elevations Topic 1: Fundamentals of Engineering Graphics and Technology 13

18 SECTION 11. REFERENCE GRIDS 11.1 General 11.2 Grid Notation 11.3 Modular Grids 11.4 Gridded Paper SECTION 12. PROJECTION 12.1 General SECTION 13. DESIGNATION AND LOCATION OF SPACES AND COMPONENTS ON DRAWINGS 13.1 General 13.2 Floors 13.3 Rooms and Spaces (including Walk-In Cupboards and other Spaces) 13.4 Non-Structural Components SECTION 14. REPRESENTATION OF MATERIALS 14.1 General 14.2 Colouring SECTION 15. GRAPHICAL SYMBOLS AND REPRESENTATION 15.1 General 15.2 Types of Symbols 15.3 Graphical Symbols SECTION 16. SYMBOLS SECTION 17. REINFORCED CONCRETE DRAWINGS 17.1 General 17.2 Sketch Drawings 17.3 Design Drawings 17.4 Working Drawings Layout drawings Concrete details Services details Reinforcement details Representation of special type floors SECTION 18. STRUCTURAL STEELWORK DRAWINGS 18.1 General 18.2 Sketch Drawings 18.3 Design Drawings 18.4 Working Drawings Layout drawings Fabricators drawings 18.5 Drawing Sizes 18.6 Dimensions 18.7 Notation of Members 18.8 Revisions of Drawings 18.9 Fasteners General Holding-down bolts Welding Symbols SECTION 19. SERVICES DRAWINGS 19.1 General 19.2 Sketch Drawings 19.3 Design Drawings 19.4 Working Drawings Installation drawings Detail drawings 19.5 Mechanical Ventilation and Air-Conditioning General 14 Topic 1: Fundamentals of Engineering Graphics and Technology

19 Layout drawings Dimensioning of ducts Holes through structure Illustrative example 19.6 Electrical Work General Layout drawings Symbolic or diagrammatic drawings 19.7 Pipework General Layout drawings Symbols Pipelines SECTION 20. SCHEDULES 20.1 General 20.2 Uses 20.3 Formulation 20.4 Detail of Schedule 2. Section 4: Lines, letters, figures and symbols, and arrowheads Assessment activity 2.2 Individual activity Students will need: A few sheets of paper. A sharp pencil. An eraser. Students must show how they reached the final drawing. A curved line Topic 1: Fundamentals of Engineering Graphics and Technology 15

20 Square Rectangle Triangle Circle An arc between a straight and a curved line An arc between two curved lines Hexagon Octagon 16 Topic 1: Fundamentals of Engineering Graphics and Technology

21 Ellipse Peer assessment: Once the students have completed the task, they must exchange their drawings with a friend and give constructive criticism on one another s work. Assessment activity 2.3 Pair activity Students will need: A few sheets of paper. A sharp pencil. An eraser. Topic 1: Fundamentals of Engineering Graphics and Technology 17

22 Peer assessment: The student s drawings will be assessed by a peer member according to the following rubric. Criteria Not yet competent Competent Did the student draw each line at least twice? Did the student give the correct description of each line? Did the student complete the activity on his/her own? Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Unit 2.2: Explain and illustrate different sizes of lettering and numbering applications This unit deals with the different sizes of lettering and numbering applications. Review the unit in the Student s Book carefully. Complete your lesson preparation form. Assessment activity 2.4 Individual activity Students will need: Sheets of paper. A sharp pencil. An eraser. A ruler. 18 Topic 1: Fundamentals of Engineering Graphics and Technology

23 Peer assessment: After completing the task, students must exchange their work with a friend, and give constructive comments on one another s work. Show the students how their work should look using the given drawings. Unit 2.3: Explain and draw to illustrate the purpose of engineering graphics and technology (mechanical) drawing conventions. This unit deals with engineering graphics and technology (mechanical) drawing conventions and why they are used. Review the unit in the Student s Book carefully. Complete your lesson preparation form. Assessment activity 2.5 Individual activity Students will need: A sheet of paper. A sharp pencil. An eraser. A ruler. A protractor. A drawing board. Tape. T-square and set squares Studs are shafts that have threads at both ends. The one side is threaded into a threaded hole and the other side is covered by a nut that keeps the part together. Topic 1: Fundamentals of Engineering Graphics and Technology 19

24 3. 4. The radius is put in such a position that it does not interfere with other dimensions. 5. The diameter is the distance of a line crossing from one side of a circle to the opposite side. The dimension line should never be horizontal or vertical, but should always be at a skew angle. 6. A chamfer is created when a corner is machined at a certain angle to remove a sharp edge. It is used for a specific purpose such as safety (removing sharp corners), and for easy fitting of bolts into holes. 7. Peer assessment: After completing the task, students must exchange their work with a friend, and make constructive comments on one another s work. Show the students how their work should look like using the given drawings and by providing the correct answers. Summative assessment (p50 in the Student s Book) Theoretical assessment [40] 1. Freehand drawings are done without the use of drawing instruments. This means that all [2] elements: lines, lettering and numbering are done by simply drawing with a pencil. Freehand drawings are done to communicate ideas and to draw drafts before creating the final, technically correct drawing. It is important that the proportion of freehand sketches is good even if you are not using instruments. 2. Freehand sketching: [4] Helps to sort out ideas and helps you decide which ideas are best. 20 Topic 1: Fundamentals of Engineering Graphics and Technology

25 Is something to show to other people in order to get their input and opinions. Is a good way of preparing for drawing with instruments. Helps to plan and place the positions of drawings as they will be on the drawing sheet. 3. Stencils are also called templates. They are plastic or paper objects with shapes, figures, letters [3] or symbols cut out of them. These shapes, figures, letters and numbers are of a specific size or scale. Stencils make drawing certain things easier as you do not have to measure out the sizes before drawing. 4. The height h of capital letters is taken as the basis for dimensioning. The standard values [1] of h are 2,5 mm; 3,5 mm; 5 mm; 7 mm; 10 mm; 14 mm and 20 mm. The titles of a drawing, as well as the subtitles are written or printed in larger letters than descriptions or details. 5. The distance between the letters and numbers should be about a 1 of their height. [1] 3 Letters and numbers should always be written/printed between two faint guidelines. 6. [12] Alphabet Line Description General uses A Continuous thick (straight or A1 Visible outlines curved) A2 Visible edges B Continuous thin (straight or curved) B1 Imaginary lines of intersection B2 Dimension lines B3 Projection lines B4 Leader lines B5 Hatching B6 Outlines of revolved sections in place B7 Short centre lines B8 Bending lines BB Continuous think and faint BB1 Construction lines BB2 Guidelines C Continuous think freehand C1 Limits of partial or interrupted views and sections, if the limit is not a chain line D Continuous think (straight) D1 Break line with zigzags E Dashed thick E1 Hidden outlines E2 Hidden edges F Dashed thin F1 Hidden outlines F2 Hidden edges G Chain thin G1 Centre lines G2 Lines of symmetry G3 Trajectories H Chain thin, thick at ends and changes of direction H1 Cutting planes J Chain thick J1 Indication of lines or surface to which a special requirement applies K Chain thin double-dashed Phantom lines * If everything is correct, give the student a bonus point. K1 Outlines of adjacent parts K2 Alternative or extreme positions of movable parts K3 Centroidal lines K4 Initial lines prior to forming K5 Parts situated in front of the cutting plane 7. Hatched lines are drawn at an angle of 45 and must be spaced equally from one another. [3] They are used when you have cut through an object and are showing a section view of a solid object. Hatchings like the ones shown below are often used for metal surfaces, with other surfaces being cross-hatched. Topic 1: Fundamentals of Engineering Graphics and Technology 21

26 8. You can use the procedure below to print letters and numbers on your drawings: [4] Use dividers or a compass to measure and set the required height that your letters and numbers have to be. Holding the dividers or compass vertically, make two small marks on your drawing sheet at the correct places. Use a 2H pencil to draw a thin, feint line through each of the marks that you made. You can now start printing your letters and numbers between the lines. 9. When a hole has been drilled for a screw, the thread has to be cut into the hole. [3] The thread is the circular cut spiralling downwards into the hole. This cutting of the metal gives the bolt the needed place to screw into. A hole has internal thread and a bolt has external thread. 10. Keys and keyways are used to transfer forces from a rotating shaft to another shaft or [3] disk or gear. The length of a keyway is determined by the designing engineer according to certain specifications, but the length is usually 1.5 to 2 times the shaft s diameter. 11. PCD is an abbreviation for pitch circle diameter. It is the diameter of a circular feature [4] that will be machined at that diameter. For instance, a gear s PCD is the distance at which the gear s teeth are cut to a certain degree, and where two gear s teeth connect to transfer power from one gear to another. Practical assessment (C/NyC) Students have to do the following practical activities on their own. They will need: Sheets of paper. A sharp pencil. An eraser. 1. Draw the following freehand: Circle Square 1a. 1b. 22 Topic 1: Fundamentals of Engineering Graphics and Technology

27 Assessment: The students freehand drawings will be assessed by the lecturer according to the following assessment rubric. Criteria Not yet competent Competent Did the student use the correct method to draw a circle? Did the student use the correct method to draw a square? Are the drawings neat and clear? Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) a Tapped holes 4b Studs 4c Keyholes and keys Topic 1: Fundamentals of Engineering Graphics and Technology 23

28 4d Chamfers Topic 1: Fundamentals of Engineering Graphics and Technology

29 Assessment: The following assessment rubric can be used to assess the student s drawings for questions 4 8. Criteria Not yet competent Competent The student demonstrates full knowledge (more than required), with explanations and elaboration. Sections conform to drawing conventions. Appropriate line styles and weight (quality of lines) are used. Correct application of the various types of lines such as the use of centre lines, break lines, etc. are used. Dimension lines constructed with correct extension lines and gaps are used. The arrowheads are all in the same style and the same size. The labels/dimensions are laid out in clear and consistent positions. The letters/figures are of uniform size and legible. Beginning (0-39%) Developing (40-49%) Accomplished (50-69%) Highly competent (70-79%) Outstanding (80-100%) Topic 1: Fundamentals of Engineering Graphics and Technology 25