ENGINEERING GRAPHICS AND DESIGN: YEAR PLAN AND CONTENTS This book will treat the year`s work for Grade 10, in the sequence shown below. NOTE: This sequence is a small departure from the Official CAPS document. 1 2 3 4 6 7 8 9 10 Topic The outlay of the curriculum in this book. Introduction to and the purpose of EGD. Analytical and visualization exercises. General drawing principles. Setting up a drawing sheet. Freehand drawing. Geometrical constructions. Scales. PAT - Practical Assessment Task. Descriptive geometry. Examinable Content The sequence of the curriculum, followed in this book. P1 WEEK 1 Purpose; scope and career opportunities; classroom organization. P2- WEEK 1 Views, projection placings, width/depth/height. Applicable to Mechanical, Civil and Electrical drawings. P6-2 WEEKS 2 Use and care of drawing instruments; dangers of sharp instruments (HIV/Aids); line types and line work; lettering (writing) and annotations; dimensioning techniques and conventions. P26-42 WEEK 3-4 P43-46 WEEK Freehand drawing techniques. P47-3 WEEKS -6 Instrumental constructions; regular polygons and ellipses. P4-81 WEEKS 7-11 The application of any scale. P82-8 WEEK 12 The design process: Problem identification; design brief; specifications; limitations; research; ideas and concepts; selection; presentation and evaluation. P86-98 WEEK 13 Points and line segments; true lengths; true inclinations and true shapes. P99-108 WEEKS 14-1 11 12 13 Solid geometry and sections. Mechanical drawing. Isometric drawing. Right-regular solids, with sections and true shapes. P109-119 WEEKS 16-18 All Mechanical drawings must be presented as 3rd Angle Orthographic working drawings, as per SANS guidelines. Castings only. P120-18 WEEKS 19-21 Simple isometric drawings, with auxiliary views. P19-169 WEEKS 22-23 Design brief; specifications and constraints; external research. PAT - Practical Three ideas, analytical and graphic (freehand drawings). 14 Assessment Task. The best solution. P170 WEEK 24 1 Perspective drawing. Single-point perspective drawing. P170-181 WEEKS 2-26 Single-storey dwellings; floor plans; basic single line elevations; 16 Civil drawing. sectional elevations, foundation to slab; annotations and labels; dimensioning; scales; abbreviations; conventions; on the floor plan: doors and windows; hatching; perimeters and floor areas. P182-191 WEEKS 26-28 17 Electrical and Simple circuit diagrams. Electronic drawing. P192-202 WEEK 29 18 Computers/CAD. Computers; hard and software. CAD: basic techniques/preparation. P203-231 ZACHEN 1
GEOMETRICAL CONSTRUCTIONS: Regular polygons. A polygon is a many sided (many angled) plane figure. A regular polygon is one where all the sides are the same length and all the angles are equal. In grade 10 we must be able to draw polygons with the following number of sides: 3 4 6 8 Draw side ab. Draw arc ab through c. Draw arc bc. 1 c 2 3 36 36 a b 4 6 With exercise in mind, can you think of a method to draw a (regular) square? Required: Example Draw a regular polygon with five sides (pentagon) = 2 mm. Step 1 Step 2 Step 3 Draw A = 2 mm Extend A to Z and with centre and radius = A, draw a semi-circle. Use dividers or a protractor to accurately divide the semi-circle into equal parts. Step 4 Step Step 6 Draw rays from through these divisions. (Omit -1, as one side, A, is already drawn). Draw the following polygons. 1. A regular octagon with 20 mm sides. 2. A regular hexagon with 27 mm sides. Set a compass to R = A. With C as centre, draw an arc on ray -3. With A as centre draw an arc on -4. Exercises. Work book p 20. ZACHEN 71 Complete the pentagon by joining the points.
TOPIC 8 SCALES apply basic constructions to simple line and scale drawings including drawing/calculating the scales themselves. All scale constructions can be avoided by making use of calculations. Scales (any scale). The calculation-method. Graphics sometimes require us to draw very small (or very large) objects. Just think how difficult it would be to draw a very small part for a ladies` wrist watch, true size! How would you, for example, draw a house on an A-3 drawing sheet? To overcome these problems, we make use of scales. We can scale UP (enlarge - in CAD we name this zoom +), or scale DOWN (make smaller, zoom -). Of course, in CAD this is easy and will be treated, later on. The easiest way (for everyday drawing work) is to use a pocket calculator! Let us use the bicycle on page 84 as an example. This bicycle is 2 metres long (2000 mm). It must therefore be scaled DOWN (drawn smaller) to fit onto (say) an A-3 drawing sheet! The instructions require it to be drawn to a 1:10 scale. This means that we must draw it one tenth of its real size. Take a wheel as an example. It has a diameter of 00 mm. We now divide the 00 mm by 10 (with the calculator) and this 0 mm result is then the new size (1:10) of the wheel, on our drawing. This also applies to the rest of the dimensions! Note: Angle sizes of course remain the same! 60 remains 60. Can you tell why? Exercise 4, on the same page, must be drawn larger (:1). Five times larger than the given dimensions! Ø 4 is now calculated to be Ø 20 and the drawing will be five times larger. Note: Although we have respectively enlarged and decreased these two drawings, the dimension values remain the same as the original ones. We do not enter the new calculated sizes onto our drawing! The scale that you used to enlarge/decrease your drawing, is written clearly at the title block to avoid confusion. ZACHEN 82
DRAWINGS: PLACEMENT PLANNING Step 1: Determine the size of the block into which the front view will fit (dimensions excluded!). A 28 10 Here, approximately 160 x 38 mm. (Dashed line rectangle). Note: Allowance is also made for the extension of the centre lines! 80 10 This view (only the drawing, with no dimensions), requires a space of 160 x 90 mm. The dimensions for the right view can now be derived from the front and the top views! No dimensions yet! 38 C 90 ZACHEN 96
TRUE SHAPES OF LAMINAS Example exercise 1: 1 2 Given: TRUE SHAPE X Y X Y Steps: 1. Draw the front and top views of the lamina. Dimensioning not necessary. 2. Use the front (edge) view as an X-Y line and project the true shape across it. (can you see the similarities between the determining of the true lengths of lines and the true shapes of laminas?). 3. Therefore use, as there, the rule of similarity. Example exercise 2: Steps: As example 1. Would it have made any difference, if you had placed an X-Y line between the top view and the true shape, in stead of using the edge view as an X-Y line? 3 4 Given: X Y X Y ZACHEN 117 TRUE SHAPE
THE LOCATION OF OJECTS FROM INDUSTRY IN THE THIRD QUADRANT Multi-view scale drawings. The figure shows a front and a top view of a cover plate, in third angle orthographic projection. Draw, full size and in third angle orthographic projection, the following views: The given front view A left view Insert 10 dimensions, the projection system symbol, as well as the title and scale. Work book p 72. FIG. 1 R12 76 44 Ø8 FIG. 2 R12 Ø10 Ø6 Ø28 12 28 11 24 70 80 30 Ø42 10 ZACHEN 17
CIVIL ENGINEERING GRAPHICS AND DESIGN: Foundations. The drawing (1) below shows examples of equipment used for setting our foundations (here 220 mm walls). The 600 mm dimension shows the width of the trough. It is made up of three pieces of wood, with four nails driven into the horizontal piece, at correctly spaced intervals. Lines are then strung between two or more of these guides. Troughs are then dug, between these lines for the concrete foundations. Work book p 92-93. 600 220 Marked out with lines of calcium/cement and ready for excavations! The completed trough. Note: The depth of the trough is determined by the depth of the underlying stable ground formation. Here the soil is not stable enough and steel re-enforcing was required. Wooden stakes are driven in, as a guide for the level of the concrete mass of the foundation. The completed concrete foundation mass. The thickness is determined by the type of the wall to be supported (built) (here 220 or 110). Stake Concrete mass ZACHEN 190
ELECTRICAL AND ELECTRONIC GRAPHICS AND DESIGN Sub-circuits relating to dwellings. Work book p 94. DOOR ELL Pushbutton 07-07-02 ell 08-11-06 attery The above circuit shows the wiring and connections for a door bell. It is battery-operated (usually 6-9 volts DC) and you may safely work on such a circuit. 3 4 The photo to the right, shows a practical example of a simple circuit diagram. Identify each component and then make a neat freehand drawing of the SANS symbol of each item. Use instruments and draw a diagram similar to the one, shown above. 2 1 LIGHTING Power bar Circuit breaker (07-13-0) Partial distribution board Lamp and switch sub-sub-circuit Three lamps (in parallel), connected to a dimmer switch.(11-14-08) Neutral bar Earth bar Earth wire (if required) This sub-circuit shows the lights to three rooms in a dwelling. Each of the first two lamps is in series with a single pole switch. The third (usually the lounge) has three parallel connected lamps, controlled by means of a dimmer switch. If the lamps have exposed metal areas, an earth connection becomes mandatory. Work book p 94. ZACHEN 19