Introduction to Engineering drawing and Graphics
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This chapter provides an overview of engineering drawings and their components. It discusses drawing standards, the graphics and word languages used to describe objects, and traditional drawing tools. It also covers topics like line types, lettering, scales, and layout of a drawing sheet. Engineering drawings combine graphics and text to precisely depict the size, shape, and specifications of objects in a standardized way to facilitate understanding between technical teams.
Introduction to Engineering drawing and Graphics
- 1. Chapter 1 Overview of an Engineering Drawing
- 2. TOPICS Drawing standards Graphics language Engineering drawing Traditional Drawing Tools Lettering
- 4. 1. Try to write a description of this object. 2. Test your written description by having someone attempt to make a sketch from your description. Effectiveness of Graphics Language The word languages are inadequate for describing the size, shape and features completely as well as concisely. You can easily understand that …
- 5. Graphic language in “engineering application” use lines to represent the surfaces, edges and contours of objects. A drawing can be done using freehand, instruments or computer methods. Composition of Graphic Language The language is known as “drawing” or “drafting” .
- 6. Freehand drawing The lines are sketched without using instruments other than pencils and erasers. Example
- 7. Instrument drawing Instruments are used to draw straight lines, circles, and curves concisely and accurately. Thus, the drawings are usually made to scale. Example
- 8. Computer drawing The drawings are usually made by commercial software such as AutoCAD, solid works etc. Example
- 10. Elements of Engineering Drawing Engineering drawing are made up of graphics language and word language. Graphics language Describe a shape (mainly). Word language Describe size, location and specification of the object.
- 11. Basic Knowledge for Drafting Graphics language Word language Line types Geometric construction Lettering Projection method
- 12. Drawing Standard
- 13. Introduction Standards are set of rules that govern how technical drawings are represented. Drawing standards are used so that drawings convey the same meaning to everyone who reads them.
- 14. ISO International Standards Organization Standard Code ANSI American National Standard InstituteUSA JIS Japanese Industrial StandardJapan BS British StandardUK AS Australian StandardAustralia Deutsches Institut für NormungDINGermany Country Code Full name มอก. สำนักงำนมำตรฐำนผลิตภัณฑ์อุตสำหกรรมThailand
- 15. Drawing Sheet Trimmed paper of a size A0 ~ A4. Standard sheet size (JIS) A4 210 x 297 A3 297 x 420 A2 420 x 594 A1 594 x 841 A0 841 x 1189 A4 A3 A2 A1 A0(Dimensions in millimeters)
- 16. Drawing space Drawing space Title block d d c c c Border lines 1. Type X (A0~A4) 2. Type Y (A4 only) Orientation of drawing sheet Title block Sheet size c (min) d (min) A4 10 25 A3 10 25 A2 10 25 A1 20 25 A0 20 25
- 17. Drawing Scales Scale is the ratio of the linear dimension of an element of an object shown in the drawing to the real linear dimension of the same element of the object. Size in drawing Actual size Length, size :
- 18. Drawing Scales Designation of a scale consists of the word “SCALE” followed by the indication of its ratio, as follow SCALE 1:1 for full size SCALE X:1 for enlargement scales (X > 1) SCALE 1:X for reduction scales (X > 1) Dimension numbers shown in the drawing are correspond to “true size” of the object and they are independent of the scale used in creating that drawing.
- 19. Basic Line Types Types of Lines Appearance Name according to application Continuous thick line Visible line Continuous thin line Dimension line Extension line Leader line Dash thick line Hidden line Chain thin line Center line NOTE : We will learn other types of line in later chapters.
- 20. Visible lines represent features that can be seen in the current view Meaning of Lines Hidden lines represent features that can not be seen in the current view Center line represents symmetry, path of motion, centers of circles, axis of axisymmetrical parts Dimension and Extension lines indicate the sizes and location of features on a drawing
- 21. Example : Line conventions in engineering drawing
- 23. DRAWING TOOLS
- 24. 1. T-Square 2. Triangles DRAWING TOOLS
- 25. 3. Adhesive Tape 4. Pencils 2H or HB for thick line 4H for thin line DRAWING TOOLS
- 26. 5. Sandpaper 6. Compass DRAWING TOOLS
- 27. 7. Pencil Eraser 8. Erasing Shield DRAWING TOOLS
- 28. 9. Circle Template 10. Tissue paper DRAWING TOOLS
- 29. 11. Sharpener 12. Clean paper DRAWING TOOLS
- 31. Text on Drawings Text on engineering drawing is used : To communicate nongraphic information. As a substitute for graphic information, in those instance where text can communicate the needed information more clearly and quickly. Uniformity - size - line thickness Legibility - shape - space between letters and words Thus, it must be written with
- 32. Lettering Standard ANSI Standard This course Use a Gothic text style, either inclined or vertical. Use all capital letters. Use 3 mm for most text height. Space between lines of text is at least 1/3 of text height. Use only a vertical Gothic text style. Use both capital and lower-case letters. Same. For letters in title block it is recommend to use 5~8 mm text height N/A. Follows ANSI rule.
- 33. Basic Strokes Straight Slanted CurvedHorizontal 1 1 2 3 Examples : Application of basic stroke “I” letter “A” letter 1 2 3 4 5 6 “B” letter
- 34. Suggested Strokes Sequence Straight line letters Curved line letters Curved line letters & Numerals Upper-case letters & Numerals
- 35. The text’ s body height is about 2/3 the height of a capital letter. Suggested Strokes SequenceLower-case letters
- 36. Stroke Sequence I L T F E H
- 37. V X W Stroke Sequence
- 38. N M K Z Y A Stroke Sequence 4
- 39. O Q C G Stroke Sequence
- 40. D U P B R J Stroke Sequence 1 2
- 44. Stroke Sequence v w x k z
- 45. Stroke Sequence j y f r t
- 46. Stroke Sequence c o a b d p q e
- 47. Stroke Sequence g n m h u s
- 48. Word Composition Look at the same word having different spacing between letters. JIRAPONG JI GOR NPA Which one is easier to read ? A) Non-uniform spacing B) Uniform spacing
- 49. Word Composition JIRAPONG / | )( )| (| Space between the letters depends on the contour of the letters at an adjacent side. Spacing Contour || || General conclusions are: Good spacing creates approximately equal background area between letters.
- 50. 1. Straight - Straight 2. Straight - Curve 3. Straight - Slant 4. Curve - Curve Space between Letters
- 51. 6. Slant - Slant5. Curve - Slant 7. The letter “L” and “T” ≡ slant slant ≡ slant straight Space between Letters
- 52. GOOD Not uniform in style. Not uniform in height. Not uniformly vertical or inclined. Not uniform in thickness of stroke. Area between letters not uniform. Area between words not uniform. Example : Good and Poor Lettering
- 53. Leave the space between words equal to the space requires for writing a letter “O”. Example Sentence Composition ALL DIMENSIONS ARE IN MILLIMETERS O O O OUNLESS OTHERWISE SPECIFIED.O
- 54. End of Chapter 1 Overview of an Engineering Drawing