Engineering graphics basics
- 1. 20GE102-ENGINEERING GRAPHICS FACULTY NAME : Mr.R.PERIYASAMY, AP/MECH KONGUNADU COLLEGE OF ENGINEERING & TECHNOLOGY (AUTONOMOUS) DEPARTMENT OF SCIENCE AND HUMANITIES
- 4. Objective OBJECTIVES: • To develop in students, graphic skills for communication of concepts, ideas and design of Engineering products • To expose them to existing national standards related to technical drawings.
- 5. WHAT IS DRAWING ?
- 6. A picture/drawing is worth a thousand words..
- 7. DRAWING Describing any object / information diagrammatically is called drawing
- 8. Difference between drawing and Engineering drawing
- 9. Engineering drawing • Engineering drawing – A drawing of an object that contains all information like • actual shape • accurate size • Dimensions, etc.,
- 10. Universal language • Drawings prepared in one country may be utilised in any other country irrespective of the language spoken. • Hence, engineering graphics is called the universal language of engineers
- 11. Engineering Drawing Manual Drawing CAD Software If basic fundamentals are clear, better use can be made of the power of the software. To be an expert in technical drawing, this first course on Engineering (manual) Drawing is the first step. Why we go for manual drawing?
- 12. Role of engineering graphics • The ability to read drawing is the most important requirement of all technical people in any profession as compared to verbal or written description • 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, analyse and communicate, and 4. Capacity to understand other subjects.
- 13. Applications of engineering drawing • Building drawing for civil engineers • Machine drawing for mechanical engineers • Circuit diagrams for electrical and electronics engineers
- 16. Circuit diagrams
- 17. • How to start drawing ? • What are all the instruments required to drawing? • What are all the specifications of instruments? • How to letter and dimension the drawing?
- 19. Instruments for Drawing The following drawing instruments are required for preparing a neat and correct drawing. (a) Basic Instruments. • Drawing board • Drawing sheet • Drawing pencil • Drawing clips or pins • Eraser • Eraser shield (b) Instruments for Drawing Straight Lines. • T- square. • Set- squares
- 20. c) Instruments for Drawing Curved Lines. • Large size compass • Small bow compass • French curve (d) Instruments for Measuring Distance. • Large size divider • Small bow divider • Scales (e) Instruments for Measuring Angles. • Protractors • Set-squares (f) Special Tool. • Mini drafter
- 21. Basics instruments Drawing board • A drawing board with its working surface upward as shown in fig.1 • The top surface of the board is perfectly smooth and level. • Fig. 2 shows the bottom of the drawing board. A drawing board is rectangular in shape and is made of well seasoned soft wood such as oak or pine
- 22. Drawing board
- 23. Sizes of drawing board Last two sizes are normally used for student drawing
- 24. Drawing sheet The drawing is frequently made in pencil on the drawing sheet. The best drawing sheet has the following qualities: • Light cream buff in colour to have good appearance • Fine grains to pick up the graphite and produce clean, dense black lines • Superior erasing qualities • Folding strength • Toughness • Smooth surface
- 25. Sizes of drawing sheet
- 26. Pencils to be used • 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. • Wooden pencils – are graded and designated by numbers and letters • Mechanical clutch pencils – Not allowed • 7B, 6B, 5B, 4B, 3B, 2B, B - in decreasing order of softness and blackness • HB to F – Medium grade • H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H – increasing order of hardness.
- 27. Grades and designations of pencil Drawings are done using 2H pencils and finished with H and HB pencils – to be practiced in this course.
- 28. Drawing clips or pins
- 29. Eraser and Eraser shield
- 30. Instruments for drawing straight lines T- square • It is composed of a long strip called blade, which is screwed rigidly at right angle to a shorter piece called head or stock. • It is made of mahogany or pear wood, which is harder than the board wood. • T- Square is used for making horizontal, vertical, inclined or parallel lines on the drawing sheet.
- 31. T- square
- 32. Set square
- 33. French curve
- 34. Instruments required for measuring • Dividers are used to divide straight or curved lines into desired number of equal parts Large Size Divider. • The dividers has two legs hinged at the upper end and is provided with steel pins at both the lower ends, but it does not have the knee joints
- 35. Small Bow Divider. Large Size Divider.
- 36. scales • Scales are made of wood, steel, celluloid or plastic • Stainless steel scales are more durable • Scale may be flat or of triangular cross- section. • 15 cm long and 2 cm wide or 30 cm long or 3 cm wide flat scales are commonly used
- 38. Protractor • Protractors or Pro-circles are used for drawing any desired angle. • These are made of hard transparent plastic. • The edges are either squared or beveled
- 39. Mini-Draughter
- 40. How to fix the mini draughter
- 41. Procedure to use mini draughter • Set the protractor head with reference mark indexing zero degree. • A T-square, protractor and set squares can be replaced by a drawing drafter. With this, lines can be drawn at any desired angle. • A mini drafter is made with several links. The scale is attached at the working end of the links. The scale unit can be rotated and set at any desired angle. • The clamp end is fixed to the upper or lower edge of the drawing board. • There is no need to have a working edge on a drawing board when a mini drafter is used. • Place the drawing sheet underneath the scales of the mini- drafter, • Mini drafter saves considerable time.
- 42. Lettering Lettering: • Writing of titles, dimensions, notes and other important particulars on a drawing is called lettering • Lettering is the most important part of a drawing. Sometimes accurate and neat drawing is spoiled by poor lettering. Therefore lettering should be done properly in clear, legible and uniform style • It should be in plain and simple style so that it could be done freehand and speedily. • There are several ways in which lettering can be done. These include both hand lettering and mechanical lettering • Hand lettering practice is universal and always of value
- 43. Sizes of the letter • Lettering should be in CAPITAL letters (upper cases) • Lower cases used only for abbreviations like, mm , cm etc.., • Size of Letters is measured by the height h of the CAPITAL letters as well as numerals. • Standard heights for CAPITAL letters and numerals recommended by BIS are given below : • 1.8, 2.5, 3.5, 5, 6, 10, 14 and 20 mm • Note: Size of the letters may be selected based upon the size of drawing.
- 44. Examples
- 45. Dimensioning: • An engineering drawing should contain the details regarding the sizes, besides giving the shape of an object. • Dimension is a numerical value expressed in appropriate units of measurement and marked on a drawing with lines, symbols and notes. • The dimensions without any unit is considered in mm
- 46. ARROW HEADS
- 50. Layout
- 51. Title block
- 52. TYPES OF LINES AND ITS APPLICATIONS
- 55. CONIC SECTIONS ELLIPSE, PARABOLA AND HYPERBOLA ARE CALLED CONIC SECTIONS BECAUSE THESE CURVES APPEAR ON THE SURFACE OF A CONE WHEN IT IS CUT BY SOME TYPICAL CUTTING PLANES. Section Plane Through Generators Ellipse Section Plane Parallel to end generator. Section Plane Parallel to Axis. Hyperbola
- 61. FOUR QUADRANTS
- 63. • TYPES OF ORTHOGRAPHIC PROJECTION The following are the types of orthographic projections. • First angle projection • Second angle projection • Third angle projection • Fourth angle projection • In engineering drawing we are preferring only the first angle projection.
- 67. • Isometric projection is a method for visually representing three-dimensional objects in two dimensions in technical and engineering drawings.