Engineering graphics introduction
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Here are the solutions to the practice problems on Sheet No. 1: 1. Types of lines: - Visible lines (thin continuous lines) for visible edges. - Hidden lines (thin dotted lines) for hidden edges. - Center lines (thin-thick lines) to indicate center of circles or arcs. - Dimension lines (thin continuous lines) for placing dimensions. - Extension lines (thin continuous lines) for extending dimension lines. - Section lines (pairs of thin lines spaced parallel) for indicating sections. 2. Dimensioning methods shown with examples of different types of dimensions like linear, angular, radius, diameter etc. 3. Constructed regular polygons for a side of 30mm
Engineering graphics introduction
- 1. MECHANICAL ENGINEERING ENGINEERING GRAPHICS AND DESIGN
- 2. INTRODUCTION Engineering drawing is a two dimensional representation of three dimensional objects. In general, it provides necessary information about the shape, size, surface quality, material, manufacturing process, etc., of the object. It is the graphic language from which a trained person can visualize objects. Drawings prepared in one country may be utilized in any other country irrespective of the language spoken. Hence, engineering drawing is called the universal language of engineers. Any language to be communicative should follow certain rules so that it conveys the same meaning to everyone. Similarly, drawing practice must follow certain rules, if it is to serve as a means of communication. For this purpose, Bureau of Indian Standards (BIS) adapted the International Standards on code of practice for drawing. The other foreign standards are: DIN of Germany, BS of Britain and ANSI of America. Role of Engineering Drawing:- The ability to read drawing is the most important requirement of all technical people in any profession. As compared to verbal or written description, this method is brief and clearer. Some of the applications are: building drawing for civil engineers, machine drawing for mechanical engineers, circuit diagrams for electrical and electronics engineers, computer graphics for one and all. The subject in general is designed to impart the following skills. 1. Ability to read and prepare engineering drawings. 2. Ability to make free - hand sketching of objects. 3. Power to imagine, analyze and communicate, and 4. Capacity to understand other subjects: SP 46 : 2003 Engineering Drawing Practice for Schools and Colleges:- "SP 46 : 2003" is special publication of Bureau of Indian Standards (B.I.S.) released in the year 2003. The ISBN number is 8170610192 number of pages 205 and MRP is Rs. 1440=00. It is the composition of some of the standards felt by B.I.S. necessary for Engineering Drawing Practice for schools and colleges. It can be purchased from any leading offices of B.I.S. or via post from 9 Bahadur Shah Zafar Marg, New Delhi 110002. Prior to this SP 46 : 1988 and IS 696 : 1972 were used in the Engineering Drawing Practices.
- 3. SR.NO TOOLS 1 Drawing Board 2 Mini Drafter 3 T-Square 4 Set –Squares (30◦-60◦ and 45◦-45◦ ) 5 Compass 6 Divider 7 Protector 8 Set of Scales 9 Circle Master 10 French Curves 11 Stencil 12 Drawing Sheet 13 Sketch Book 14 Paper Clip 15 Pencils ( 2H and H only ) 16 Eraser LIST OF DRAWING TOOLS:-
- 4. Drawing Board Drawing Board Until recently drawing boards used are made of well seasoned softwood of about 25 mm thick with a working edge for T- square. Nowadays mini-drafters are used instead of T-squares which can be fixed on any board. The standard size of board depends on the size of drawing sheet size required. Mini-Drafter consists of an angle formed by two arms with scales marked and rigidly hinged to each other. It combines the functions ofT-square, set-squares, scales and protractor. It is used for drawing horizontal, vertical and inclined lines, parallel and perpendicular lines and for measuring lines and angles. Mini Drafter Instrument box contains 1. Compasses, 2.Dividers and 3. Inking pens. What is important is the position of the pencil lead with respect to the tip of the compass. It should be atleast I mm above because the tip goes into the board for grip by 1 mm. Instrument Box
- 5. Pencils Pencils with leads of different degrees of hardness or grades are available in the market. The hardness or softness of the lead is indicated by 3H, 2H, H, HB, B, 2B, 3B, etc. The grade HB denotes medium hardness oflead used for general purpose. The hardness increases as the value of the numeral before the letter H increases. The lead becomes softer, as the value of the numeral before B increases. The selection of the grade depends on the line quality desired for the drawing. Pencils of grade H or 2H may be used for finishing a pencil drawing as these give a sharp black line. Softer grade pencils are used for sketching work. HB grade is recommended for lettering and dimensioning. Nowadays mechanical pencils are widely used in place of wooden pencils. When these are used, much of the sharpening time can be saved. The number 0.5, 0.70 of the pen indicates then thickness of the line obtained with the lead and the size of the lead diameter. Micro-tip pencils with 0.5 mm thick leads with the following grades are recommended. HB Soft grade for Border lines, lettering and free sketching. H Medium grade for Visible outlines, visible edges and boundary lines 2H Hard grade for construction lines, Dimension lines, Leader lines, Extension lines, Centre lines,etc.
- 7. Polygon Construct square, pentagon, hexagon, heptagon, octagon and nonagon which have one common side of 30 mm by general method.
- 8. Plain Scale On a map of Gujarat 1 cm represents 5 kms. Construct a plain scale long enough to measure a distance between Ahmedabad and Baroda.Indicate on it a distance between Ahmedabad and Anand.Distance: (1) Ahmedabad- Baroda - 100kms.(2) Ahmedabad- Anand - 65kms
- 9. Diagonal Scale The distance between two places is 240 km and its equivalent distance on map measures 12 cm. Draw a diagonal scale to indicate 273 km and 128 km.
- 10. Sr. No. Description of the problem Topic 1 Draw the types of lines used in general engineering drawing with its description and applications. Ref. book P.J SHAH PAGE NO.21 2 Show the various dimensioning methods with example. Ref. book P.J SHAH CHAPTER-17 3 Construct square, pentagon, hexagon, heptagon, octagon and nonagon which have one common side of 30 mm by general method for drawing polygons. Polygon 4 On a map of Gujarat 1 cm represents 5 kms. Construct a plain scale long enough to measure a distance between Ahmadabad and Baroda. Indicate on it a distance between Ahmadabad and Anand. Distance: (1) Ahmadabad- Baroda - 100kms. (2) Ahmadabad- Anand - 65kms Plain scale 5 An area of 144 cm2 on a map represents an area of 36 km2 on the field. Draw the scale to show kilometers, hectometers and decameters to measure up to 10 km. Indicate on the scale a distance of 5.44 kilometers. Diagonal Scale SHEET NO. 1: PRACTICE SHEEET
- 11. SHEET NO. 1: PRACTICE SHEEET (Solution)