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Engineering Drawing
By: Engr. Rauf Ahmad
Chapter 1Introduction
LEC 01, Introduction 2
Contents
Drawing standards
Engineering drawing
Drawing sheetScaleLetteringLine types
LEC 01, Introduction 3
The things you need
LEC 01, Introduction 4
Items required for drawing Items required for drawing
Drawing board (Available in Drawing Halls)Drawing sheet (Half Scholar Sheet)Mini-drafter/drafting machine/T- square(2ft or 3ft)Instrument box containing compass, divider, etc.Scales(6in. or 12in.)Set-Squares & Protractor(30cm)French curves(not required)Drawing pencils(A lots of them)Eraser(smooth)Drawing clip/pin/adhesive tapeSharpenerDuster
LEC 01, Introduction 5
Standard sizes of drawing sheets as per BIS
A2 sizeLEC 01, Introduction 6
Instrument DrawingDrawing Pencils
High-quality drawing pencils should be used in technical drawing, never ordinary writing pencils.
Many makes of mechanical pencils are available together with refill leads in all grades. Choose a mechanical pencil that feels comfortable in your hand.
LEC 01, Introduction 7
Drawing Pencils
Wooden pencils – are graded and designated by numbers and lettersMechanical 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 ofhardness.
Drawings are done using 2H pencils and finished with Hand HB pencils – to be practiced in this course.
LEC 01, Introduction 8
Grades and designation of wooden pencilsLEC 01, Introduction 9
Pencil drawing –In finished drawing, all lines (except construction lines- used to construct the drawing) should be dense, clean and uniform. Construction line should be drawn very thin and should be hardly visible in the finished drawing ( they should not be erased).
LEC 01, Introduction 10
Line types
LEC 01, Introduction 11
Line types….CONTD
LEC 01, Introduction 12
EngineeringDrawing
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
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.
Effectiveness of Graphic Language
The word language is inadequate for describing the sizesize,
shapeshape and featuresfeatures completely as well as concisely.
You can easily understand that …
LEC 01, Introduction 14
Graphic Language inEngineering Drawing
“Engineering drawing” or “blueprint” uses llinesines torepresent the features features of an object.
Features of an object are surface surface (include planeplane) and
edgeedge.
Surface
Edge
LEC 01, Introduction 15
A drawing can be created in 3 ways
Ways to Create anEngineering Drawing
1. Freehand sketch
2. Using typical drawing instruments
3. Using a computer
LEC 01, Introduction 16
Example
Create a Drawing : Freehand sketch
The lines are drawn using only pencil and erasers on a blank or grid paper.
Pictorial sketch Orthographic sketchLEC 01, Introduction 17
Example
Create a Drawing : Using instruments
Drawing instruments are used to draw straight lines, circles, and curves conciselyconcisely and accuratelyaccurately.
Drawings are usually made to scalemade to scale.
LEC 01, Introduction 18
Example
Create a Drawing : Using a computer
Computer aided drafting (CAD) software is used.
2D drawing Solid modelingLEC 01, Introduction 19
Elements of a DrawingA clear and precise engineering drawing requires both
graphics graphics and word word languages.
Graphics language
Describe a shape (mainly).
Word language
Describe an exact size, location and specificationof the object.
LEC 01, Introduction 20
Text on drawings : Example
Generalnotes Title
block
Dimensions&
Notes
LEC 01, Introduction 21
Knowledge and Skills Require
Graphicslanguage
Wordlanguage
Dimensions & Notes
VisualizationVisualization is the ability to mentally picture things that do not exists.
VisualizationUsing line types
Geometricconstruction
Projectionmethod
Engineering Drawing
ContentsLEC 01, Introduction 22
Drawing Standard
Drawing sheet Scale Lettering Line types Contents
Definition and Necessity
Drawing standards are set of rulesset of rules that govern how
technical drawings are represented.
Drawing standards are used so that drawings conveyconveythe same meaningthe same meaning to everyone who reads them.
LEC 01, Introduction 24
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./TISสำ�นักง�นม�ตรฐ�นผลิตภัณฑ์อุตส�หกรรมThailand
LEC 01, Introduction 25
Examples of TIS Standard
มอก. 210 2520 วธิเีขยีนแบบท่ัวไป : ท�งเครื่องกลมอก 440. ล 12541. ก�รเขยีนแบบก่อสร�้งเล่ม 1 ท่ัวไป
มอก 446 ล 42532ขอ้แนะนำ�สำ�หรบัก�รเขยีนแผนภ�พวงจรไฟฟ�้มอก 1473 2540 ก�รเขยีนแบบเทคนิค ก�รติดต้ัง
สญัลักษณ์สำ�หรบัระบบท่อของเหลวระบบทำ�คว�มรอ้น ก�รระบ�ยอ�ก�ศและระบบท่ออ�ก�ศ
Code number Contents
ท่ีม� : http://library.tisi.go.th/data/lib_resources/pdf/catalog-online49/tis/02_ICS.pdfLEC 01, Introduction 26
JIS Z 8311 Sizes and Format of DrawingsSizes and Format of Drawings
JIS Z 8312 Line ConventionsLine ConventionsJIS Z 8313 LetteringLettering
JIS Z 8314 ScalesScales
JIS Z 8315 Projection methods
JIS Z 8316 Presentation of Views and Sections
JIS Z 8317 Dimensioning
Code number Contents
Examples of JIS Standard
LEC 01, Introduction 27
Drawing StandardDrawing Sheet
Drawing standard Contents
Drawing Sheet : Standard size
Trimmed paper ofa size A0 ~ A4.
Standard sheet size (JIS)
A4 210 x 297A3 297 x 420A2 420 x 594A1 594 x 841A0 841 x 1189
A4
A3
A2
A1
A0(Dimensions in millimeters)
LEC 01, Introduction 29
Drawing space
Drawingspace
Title block
d
d
c
c
cBorder lines
1. Type X (A0~A4)
2. Type Y (A4 only)
Title block
Sheet size c (min) d (min)
A4 10 25 A3 10 25 A2 10 25 A1 20 25 A0 20 25
Drawing Sheet : Orientation & Margin
LEC 01, Introduction 30
Drawing StandardDrawing Scale
Drawing standard Contents
Drawing Scales : Definition
Drawing Actual
Length, size
:
ScaleScale is a ratio between the linear dimension of a drawn representation of an object and the actual object.
1 2
LEC 01, Introduction 32
Designation of a scale consists of the word “SCALE” followed by the indication of its ratio, as follows
SCALE 1:1 for full sizeSCALE X:1 (X > 1) for an enlargementenlargement scalesSCALE 1:X (X > 1) for a reductionreduction scales
Drawing Scales : Designation
Drawing scale is commonly found in a title block.
LEC 01, Introduction 33
Dimension numbersDimension numbers shown in the drawing representthe “true size” of an object and they are independent ofthe drawing scale used.
Drawing Scales : Notes
LEC 01, Introduction 34
Standard reducing scales are1:2, 1:5, 1:10, 1:20, 1:50, 1:100
Drawing Scales : Standard scale
Standard enlarging scales are2:1, 5:1, 10:1, 20:1, 50:1, 100:1
LEC 01, Introduction 35
Drawing StandardLettering
Drawing standard Contents
- Size (or text height)- line thickness
- Shape- Space between letters- Space between words
Recommendation
LegibilityLegibility
UniformityUniformity
Text’s style on the drawingmust have the following2 properties
Examples
GOOD
Not uniform in style.
Not uniform in height.
Not uniformly vertical.
Not uniform inthickness of stroke.
Inappropriate spacebetween letters
LEC 01, Introduction 37
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.
LEC 01, Introduction 38
Basic StrokesStraight Slanted CurvedHorizontal
1 1 2
3
“I” letter “A” letter
1
2
3
4 5
6
“B” letter
Examples
LEC 01, Introduction 39
Suggested Strokes SequenceStraight line
letters
Curved lineletters
&Numerals
Upper-case Letters & Numerals
LEC 01, Introduction 40
Lower-case Letters
LEC 01, Introduction 41
I L T F
E H
Stroke Sequence : Upper-case
Skip sectionLEC 01, Introduction 42
V X W
Stroke Sequence : Upper-case
Skip sectionLEC 01, Introduction 43
N M K Z
Y A 4
Stroke Sequence : Upper-case
Skip sectionLEC 01, Introduction 44
O Q C G
Stroke Sequence : Upper-case
Skip sectionLEC 01, Introduction 45
D U P B
R J
Stroke Sequence : Upper-case
Skip sectionLEC 01, Introduction 46
5 7
Stroke Sequence : Upper-case
1 2
Skip sectionLEC 01, Introduction 47
6
8 9
0S 3
Stroke Sequence : Upper-case
Skip sectionLEC 01, Introduction 48
l i
Stroke Sequence : Lower-case
Skip sectionLEC 01, Introduction 49
v w x k
z
Stroke Sequence : Lower-case
Skip sectionLEC 01, Introduction 50
j y f
r
t
Stroke Sequence : Lower-case
Skip sectionLEC 01, Introduction 51
c o a b
d p q e
Stroke Sequence : Lower-case
Skip sectionLEC 01, Introduction 52
g n m h
u s
Stroke Sequence : Lower-case
Skip sectionLEC 01, Introduction 53
DRAWING
Word Composition
Non-uniformspacing
Uniformspacing DR A WING
Space between the letters depends on the adjacentcontour of the letters.
Word having non-uniform spacing is more readable.LEC 01, Introduction 54
Word Composition
Contour
DRAWINGContour can be denoted as “straight”, “slant” and “curve”.
Adjacent contour can be1. straight-straight : 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.
Spa
cing
LEC 01, Introduction 55
Leave the space between words equal to the spacerequires for writing a letter “O”.
Example
Sentence Composition
ALL DIMENSIONS ARE INMILLIMETERS
O O OO UNLESS
OTHERWISE SPECIFIED.O
LEC 01, Introduction 56
Drawing StandardLine Types
Drawing standard Contents
Basic Line Types &Name according to application
ContinuousDashChain
Style
Thickness Thick Thin 1. Dimension line2. Extension line3. Leader line
Center line
Hidden line
Visible line
represent features that can be seen in the current view.
represent features that can not be seen in the current view.
represents symmetry, path of motion, centers of circles,
axis of axisymmetrical parts
indicate the sizes and location of features.
1. Visible line
3. Hidden line
4. Center line
2. Dimension line Extension line Leader line
LEC 01, Introduction 58
Example
ContentsLEC 01, Introduction 59