WEEKS TOPICS 1. Introduction to technical drawing, lines, lettering, dimensioning and safety measures. 2. Uses and cares of equipment. 3. Drawing board practice and types of drawing. 4. Division of lines into given number of parts or proportion. 5. Angles. 6. Triangles. 7. Quadrilateral figures. 8. Polygons. 9. Circles. 10. Revision / Examination. MEANING OF TECHNICAL DRAWING Technical drawing is a language used in the workshop to convey an idea and instruction. It involves drafting or draughting. That is, the act and discipline of composing plans that visually communicate how something functions. The following are safety measures in technical drawing; 1. Always pay attention while drawing. 2. The right drawing tools must be used for the right job. 3. Always observe neatness while drawing. 4. Always keep your pencil well sharpened. 5. All drawing instruments must be properly kept. A line has position, length but virtually no thickness. A line may be straight or curved. A straight line is regarded as the shortest distance between two points. While a curved line is the longest distance between two points as shown below. A A A straight line A curved line B B The following are the different types of lines. 1) Thin continuous line : It is used for construction, projection, hatching and dimension lines. 2) Thick continuous line: This is used for visible outlines and edges. 3) Thin short dashes : lt is used for showing hidden outlines and edges. 4) Thin long chain : This is used for centre lines and extreme positions of moveable parts. 5) Thick long chain : It is used for cutting planes. 6) Thin wavy lines: This is used for limits of partial views or sections when the line is not an axle. 7) Arrow head lines: It is used for indicating directions and at the end of dimension lines: 8) Thick wavy lines: it is used for short break lines and irregular boundary lines. 9) Thin ruled with short zig-zags : used for long break lines. It is the act of indicating the size of an object when drawing, using an arrow head lines and thin continuous lines as shown below. TYPES OF DIMENSIONING. 1. Chain dimensioning is advantageous because the size of each feature is easy to read and is economical in space. The disadvantage is that error measurement can be cumulative that leads to large error on the overall size of the object. 2. Datum dimensioning: It enables us to measure independently from one edge and consequently errors are not cumulative. This is the act or way of writing clearly a word or statement. Lettering technique is used for designing sign post or board. Lettering can be done freehand or by mechanical means whereby stencil is used to print out the words. STYLES OF LETTERING The following are the styles of lettering 1. Gothic, 2. ltalic, 3. Celtic Lettering is either straight or slanting as shown below. CHRISLAND SECONDARY SCHOOLS, LAGOS. CHRISLAND SECONDARY SCHOOLS, LAGOS . As shown above, lettering must be done in between two lines to maintain the same height and size. CLASS WORK 1.What is technical drawing? 2. State 3 safety measures observed in technical drawing . 3. What is a line in technical drawing? 4. State the uses of 5 types of line used in technical drawing. 5. Design a sign post for chrisland schools.