- Slides: 58
Chapter 1 Introduction
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 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 Drawings are usually made to scale Example
Create a Drawing : Using a computer Computer aided drafting (CAD) software is used. Example 2 D 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 Word language Graphics language Geometric construction Using line types Projection method Dimensions & Notes 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 Thailand USA Code Full name มอก. /TIS สำนกงานมาตรฐานผลตภณฑอตสาหกรรม 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
Examples of JIS Standard Contents Code number JIS Z 8311 Sizes and Format of Drawings JIS Z 8314 Scales JIS Z 8312 Line Conventions JIS Z 8313 Lettering JIS Z 8315 Projection methods JIS Z 8316 Presentation of Views and Sections JIS Z 8317 Dimensioning
Drawing Standard Drawing Sheet Drawing standard Contents
Drawing Sheet : Standard size Trimmed paper of a size A 0 ~ A 4. Standard sheet size (JIS) A 4 A 3 A 2 A 1 A 0 210 x 297 x 420 x 594 x 841 x 1189 (Dimensions in millimeters) A 4 A 3 A 2 A 1 A 0
Drawing Sheet : Orientation & Margin c 1. Type X (A 0~A 4) Border d lines c c Drawing space Sheet size Title block 2. Type Y (A 4 only) d Drawing space Title block A 4 A 3 A 2 A 1 A 0 c (min) d (min) 10 10 10 20 20 25 25 25
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 Drawing : 2 Actual
Drawing Scales : 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 must have the following 2 properties Legibility - Shape Examples GOOD Not uniform in style. Not uniform in height. - Space between letters - Space between words Uniformity - Size (or text height) - line thickness Not uniformly vertical. Not uniform in thickness of stroke. 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 1 “A” letter 2 1 “B” letter 1 4 3 3 2 5 6
Upper-case. Strokes Letters &Sequence Numerals Suggested Straight line letters Curved line letters & Numerals
Stroke Sequence : Upper-case I L E H T F Skip section
Stroke Sequence : Upper-case V X W Skip section
Stroke Sequence : Upper-case N M K Y A 4 Z Skip section
Stroke Sequence : Upper-case O Q C G Skip section
Stroke Sequence : Upper-case D U R J P B Skip section
Stroke Sequence : Upper-case 1 2 5 7 Skip section
Stroke Sequence : Upper-case S 0 8 9 3 6 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 u n m h s Skip section
Word Composition Space between the letters depends on the adjacent contour of the letters. Non-uniform spacing Uniform spacing DRAWING D R A W IN G Word having non-uniform spacing is more readable.
Word Composition DRAWING Contour can be denoted as “straight”, “slant” and “curve”. Adjacent contour can be : II, IN, IM, IP etc. 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. Spacing 1. straight-straight
Sentence Composition Leave the space between words equal to the space requires for writing a letter “O”. Example ALL ODIMENSIONS OARE OIN MILLIMETERS OUNLESS OTHERWISE O SPECIFIED.
Drawing Standard Line Types Drawing standard Contents
Basic Line Types & Name according to application Thickness Thick Thin Visible line Style Continuous Dash Chain 1. Visible line 1. Dimension line 2. Extension line 3. Leader line Hidden line Center line represent features that can be seen in the current view. 2. Dimension line Extension line Leader line indicate the sizes and location of features. 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