JSS3 BASIC TECHNOLOGY SCHEME OF WORK FOR FIRST TERM 2014/15 WEEK 1 TOPIC ISOMETRIC DRAWING 2 3 4 Isometric drawing Oblique drawing Orthographic projection 5 Orthographic projection 6 7 One point perspective drawing Motions in engineering (linear) 8 Motions in engineering (rotary) 9 10 Revision Examination CONTENT Definition and axes, isometric drawing of simple shaped blocks without curves Board practice Definition ,oblique drawing Principal planes (vertical and horizontal), angles of projection(1stand 3rd ), principal views (front, side and plan). Placing principal views in quadrants, dimensioning techniques Definition, principles, practise Definition, linear motion, lever arrangement to produce linear motion, use of slots and slides in mechanical systems. Types9one way and reversible), principles of application, conversion of rotary motion to linear motion TOPIC: ISOMETRIC DRAWING DEFINITION ISOMETRIC AXES DIMENSIONING DRAWING OF A SIMPLE SHAPED BLOCK ISOMETRICALLY. An isometric drawing can be defined as a form of pictorial drawing which is inclined at 30 degrees to the horizontal plane Tee square Set square Rules French curves Etc A simple solid is a firm object having length, width and height. It has three principal dimensions enclosed by surfaces. Examples of simple geometrical solids are: Triangles, quadrilaterals, polygons, prisms, pyramids, cones, spheres and other solids such as tetrahedron, hexahedron, octahedron etc NOTE: CHECK Pg.23 EVANS BASIC TECH FORJSS BK.3 An axis is the imaginary line that joins the centre of the ends of regular solid Left recedin g axis Right receding axis Vertical axis Isometric drawing is built around the isometric axes as shown below This is the selection of correct measurment, the lettering and the positioning of the dimensions on a drawing. Types of dimensioning: Chain dimensioning Datum dimensioning Dimensioning are placed outside the outline of the views Extension or projection lines are used to indicate the length to be dimensioned. They are written above a horizontal lines and on the left of vertical lines. It should be spaced on the drawing. Semi circles and arcs are dimensions using their radius, R=50 Do not use centre lines and outlines as dimension lines. Circles are dimensioned by their diameters with symbol Ø. Never repeat dimensions on other views. 20 35 20 80 ALL DIMENSIONS ARE IN MM What is isometric drawing? How many axes are found on isometric drawing? Mention them. List any three essential points to note when dimensioning. Reproduce and dimension the simple block in your note. Reproduce and dimension this isometric block. 50 20 35 20 50 ALL DIMENSIONS ARE IN MM SUBMMIT HARD COPY UPON RESUMPTION THANK YOU