Presentation on theme: "JSS3 BASIC TECHNOLOGY SCHEME OF WORK FOR FIRST TERM 2014/15 WEEK TOPIC"— Presentation transcript:
1 JSS3 BASIC TECHNOLOGY SCHEME OF WORK FOR FIRST TERM 2014/15 WEEK TOPIC CONTENT1ISOMETRIC DRAWINGDefinition and axes, isometric drawing of simple shaped blocks without curves2Isometric drawingBoard practice3Oblique drawingDefinition ,oblique drawing4Orthographic projectionPrincipal planes (vertical and horizontal), angles of projection(1stand 3rd ), principal views (front, side and plan).5Placing principal views in quadrants, dimensioning techniques6One point perspective drawingDefinition, principles, practise7Motions in engineering (linear)Definition, linear motion, lever arrangement to produce linear motion, use of slots and slides in mechanicalsystems.8Motions in engineering (rotary)Types9one way and reversible), principles of application, conversion of rotary motion to linear motion9Revision10Examination
2 CONTENT: TOPIC: ISOMETRIC DRAWING DEFINITION ISOMETRIC AXES DIMENSIONINGDRAWING OF A SIMPLE SHAPED BLOCK ISOMETRICALLY.
3 DEFINITIONAn isometric drawing can be defined as a form of pictorial drawing which is inclined at 30 degrees to the horizontal plane
4 The following Instruments are used in isometric drawing for speed and accuracy Tee squareSet squareRulesFrench curvesEtc
5 What is a simple solid?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 etcNOTE: CHECK Pg.23 EVANS BASIC TECH FORJSS BK.3
6 ISOMETRIC AXESAn axis is the imaginary line that joins the centre of the ends of regular solidRight receding axisLeft receding axisVertical axisIsometric drawing is built around the isometric axes as shown below
8 DIMENSIONINGThis is the selection of correct measurment, the lettering and the positioning of the dimensions on a drawing.Types of dimensioning:Chain dimensioningDatum dimensioning
9 Essential points to note when dimeNsioning Dimensioning are placed outside the outline of the viewsExtension 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
10 Essential points contd. 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.
11 THE simple shaped block IS AN isometric DRAWING 5020352080ALL DIMENSIONS ARE IN MM
12 Evaluation 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.
13 Assignment Reproduce and dimension this isometric block. 5020352050ALL DIMENSIONS ARE IN MM