Chapter 1 Introduction to Engineering Drawing PDF

Chapter 1 Introduction to Engineering Drawing  Contents Engineering drawing Drawing standards Drawing sheet Scale Lettering Line types  Engineering Drawing The words of the...

Chapter 1 Introduction to Engineering Drawing  Contents Engineering drawing Drawing standards Drawing sheet Scale Lettering Line types  Engineering Drawing The words of the language, as they are written or spoken, do not seem to play any role in my mechanism of thought. The psychical entities which seem to serve as elements in thought are certain signs and more or less clear images which can be “voluntarily” reproduced and combined--this combinatory play seems to be the essential feature in productive thought before there is any connection with logical construction in words or other kinds of signs which are communicated to others --Albert Einstein Contents Effectiveness of Graphic Language 1. Try to write a description of this object. 2. Test your written description by having someone attempt to make a sketch or visualize from your description. You can easily understand that … The word language is inadequate for describing the size, size shape and features completely as well as concisely.  Graphic Language in Engineering Drawing “Engineering drawing” or “blueprint” uses lines to represent the features of an object. Features of an object are surface (include plane) plane and edge. edge Surface Edge  Ways to Create an Engineering Drawing A drawing can be created in 3 ways 1. Freehand sketch 2. Using typical drawing instruments 3. Using a computer Create a Drawing : Freehand sketch The lines are drawn using only pencil and erasers on a blank or grid paper. Example Pictorial sketch Orthographic sketch  Create a Drawing : Using instruments Drawing instruments are used to draw straight lines, circles, and curves concisely and accurately. accurately Drawings are usually made to scale. scale Example  Create a Drawing : Using a computer Computer aided drafting (CAD) software is used. Example 2D drawing Solid modeling  Elements of a Drawing A clear and precise engineering drawing requires both graphics and word languages. Graphics language Describe a shape (mainly). Word language Describe an exact size, location and specification of the object.  Text on drawings : Example Dimensions & Notes General notes Title block  Knowledge and Skills Require Engineering Drawing Graphics Word language language Geometric Projection construction method Dimensions & Notes Using line types Visualization Visualization is the ability to mentally picture things that do not exists. Contents  Drawing Standard Drawing sheet Scale Lettering Line types Contents  Definition and Necessity Drawing 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.  Standard Code Country Code Full name USA ANSI American National Standard Institute Japan JIS Japanese Industrial Standard UK BS British Standard Australia AS Australian Standard Germany DIN Deutsches Institut für Normung ISO International Standards Organization Drawing Standard Drawing Sheet Drawing standard Contents  Drawing Sheet : Standard size A4 Trimmed paper of a size A0 ~ A4. A3 Standard sheet size A2 (JIS) A4 210 x 297 A1 A3 297 x 420 A2 420 x 594 A1 594 x 841 A0 841 x 1189 A0 (Dimensions in millimeters)  Drawing Sheet : Orientation & Margin 1. Type X (A0~A4) c Sheet size c (min) d (min) A4 10 25 Border d Drawing space c A3 10 25 lines A2 10 25 A1 20 25 A0 20 25 c Title block 2. Type Y (A4 only) d Drawing space Title block Drawing Standard Drawing Scale Drawing standard Contents  Drawing Scales : Definition Length, size Scale is a ratio between the linear dimension of a drawn representation of an object and the actual object. 1 : 2 Drawing Actual  Drawing Scales : Designation Designation of a scale consists of the word “SCALE” followed by the indication of its ratio, as follows SCALE 1:1 for full size SCALE X:1 (X > 1) for an enlargement scales SCALE 1:X (X > 1) for a reduction scales Drawing scale is commonly found in a title block.  Drawing Scales : Notes Dimension numbers shown in the drawing represent the “true size” of an object and they are independent of the drawing scale used. Drawing Scales : Standard scale Standard reducing scales are 1:2, 1:5, 1:10, 1:20, 1:50, 1:100 Standard enlarging scales are 2:1, 5:1, 10:1, 20:1, 50:1, 100:1 Drawing Standard Lettering Drawing standard Contents  Recommendation Text’s style on the drawing Examples must have the following GOOD 2 properties Not uniform in style. Legibility - Shape Not uniform in height. - Space between letters - Space between words Not uniformly vertical. Uniformity Not uniform in thickness of stroke. - Size (or text height) - line thickness Inappropriate space between letters  Style (this course) Gothic vertical style. Begin the sentence, phrase or word with a capital letter. Text height 2~3 mm. Space between lines of text is about of text height. Height of the lower-case letter is about 2/3 of that of a capital letter.  Basic Strokes Straight Slanted Horizontal Curved Examples “I” letter “A” letter “B” letter 4 5 1 1 2 1 3 6 3 2  Suggested Upper-caseStrokes Letters &Sequence Numerals Straight line letters Curved line letters & Numerals Lower-case Letters  Stroke Sequence : Upper-case I L T F E H Skip section  Stroke Sequence : Upper-case V X W Skip section  Stroke Sequence : Upper-case N M K Z Y A 4 Skip section  Stroke Sequence : Upper-case O Q C G Skip section  Stroke Sequence : Upper-case D U P B R J Skip section  Stroke Sequence : Upper-case 1 2 5 7 Skip section  Stroke Sequence : Upper-case S 0 3 6 8 9 Skip section  Stroke Sequence : Lower-case l i Skip section  Stroke Sequence : Lower-case v w x k z Skip section  Stroke Sequence : Lower-case j y f t r Skip section  Stroke Sequence : Lower-case c o a b d p q e Skip section  Stroke Sequence : Lower-case g n m h u s Skip section  Word Composition Space between the letters depends on the adjacent contour of the letters. DRAWING Non-uniform spacing DR A WIN G Uniform spacing Word having non-uniform spacing is more readable.  Word Composition DRAWING Contour Contour can be denoted as “straight”, “slant” and “curve”. Adjacent contour can be 1. straight-straight : II, IN, IM, IP etc. Spacing 2. straight-curve (or curve-straight) : IO, QR etc. 3. straight-slant (or slant-straight) : IV, IW etc. 4. curve-curve : OO, OG etc. 5. slant-curve (or curve-slant) : VO, WG, VC etc. 6. slant-slant : VW, VX etc.  Sentence Composition Leave the space between words equal to the space requires for writing a letter “O”. Example ALL O DIMENSIONS O ARE OIN MILLIMETERS O UNLESS OTHERWISE O SPECIFIED. Drawing Standard Line Types Drawing standard Contents  Basic Line Types & Name according to application Thickness Thick Thin 1. Dimension line 2. Extension line Visible line Style 3. Leader line Continuous Hidden line Dash Chain Center line 1. Visible line represent features that can be seen in the current view. 2. Dimension line Extension line indicate the sizes and location of features. Leader line 3. Hidden line represent features that can not be seen in the current view. 4. Center line represents symmetry, path of motion, centers of circles, axis of axisymmetrical parts Example Contents