some mechanical drawing notes for eng.ppt

Document Provides steps to implement mechanical drawing for engineering students

1. Chapter 1
Introduction

2. Contents
Drawing standards
Engineering drawing
Drawing sheet
Scale
Lettering
Line types

3. 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

4. 1. Try to write a descriptionof
this object.
2. Test your written description
by having someone attempt
to make a sketchor visualize
from your description.
Effectiveness of Graphic Language
The word language is inadequatefor describing the size,
shapeand featurescompletely as well as concisely.
You can easily understand that …

5. Graphic Language in
Engineering Drawing
“Engineering drawing” or“blueprint” uses linesto
represent the features of an object.
Featuresof an object are surface (include plane) and
edge.
Surface
Edge

6. A drawing can be created in 3 ways
Ways to Create an
Engineering Drawing
1.Freehand sketch
2.Using typical drawing instruments
3.Using a computer

7. Example
Create a Drawing : Freehand sketch
The lines are drawn using only pencil and erasers on a
blank or grid paper.
Pictorial sketch Orthographic sketch

8. Example
Create a Drawing : Using instruments
Drawing instruments are used to
draw straight lines, circles, and
curves conciselyand accurately.
Drawings are usually made to scale.

9. Example
Create a Drawing : Using a computer
Computer aided drafting (CAD) software is used.
2D drawing Solid modeling

10. 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.

11. Text on drawings : Example
General
notes
Title
block
Dimensions
&
Notes

12. Knowledge and Skills Require
Graphics
language
Word
language
Dimensions & Notes
Visualizationis the ability to mentallypicture things that do not exists.
VisualizationUsing line types
Geometric
construction
Projection
method
Engineering Drawing
Contents

13. Drawing Standard
Drawing sheet Scale Lettering Line types Contents

14. Definition and Necessity
Drawing standards are set of rulesthat govern how
technical drawings are represented.
Drawing standards are used so that drawings convey
the same meaningto everyone who reads them.

15. ISO International Standards Organization
Standard Code
ANSI American National Standard InstituteUSA
JIS Japanese Industrial StandardJapan
BS British StandardUK
AS Australian StandardAustralia
Deutsches Institut fürNormungDINGermany
Country Code Full name
มอก./TISส ำนักงำนมำตรฐำนผลิตภัณฑ์อุตสำหกรรมThailand

16. Examples of TISStandard
มอก.210 2520 วิธีเขียนแบบทั่วไป : ทำงเครื่องกล
มอก. 440 ล.1 2541กำรเขียนแบบก่อสร้ำงเล่ม 1 ทั่วไป
มอก. 446ล.42532 ข้อแนะน ำส ำหรับกำรเขียน
แผนภำพวงจรไฟฟ้ำ
มอก. 1473 2540 กำรเขียนแบบเทคนิค กำรติดตั้ง
สัญลักษณ์ส ำหรับระบบท่อของเหลว
ระบบท ำควำมร้อน กำรระบำยอำกำศ
และระบบท่ออำกำศ
Code number Contents
ที่มำ : http://library.tisi.go.th/data/lib_resources/pdf/catalog-online49/tis/02_ICS.pdf

17. JIS Z 8311 Sizes and Format of Drawings
JIS Z 8312 Line Conventions
JIS Z 8313 Lettering
JIS Z 8314 Scales
JIS Z 8315 Projection methods
JIS Z 8316 Presentation of Views and Sections
JIS Z 8317 Dimensioning
Code number Contents
Examples of JISStandard

18. Drawing Standard
Drawing Sheet
Drawing standard Contents

19. Drawing Sheet : Standard size
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)

20. Drawing space
Drawing
space
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

21. Drawing Standard
Drawing Scale
Drawing standard Contents

22. Drawing Scales : Definition
Drawing Actual
Length, size
:
Scaleis a ratio between the linear dimension of a
drawn representation of an object and the actual object.
1 2

23. Designation of a scale consists of the word “SCALE”
followed by the indication of its ratio, as follows
SCALE 1:1for full size
SCALE X:1(X > 1) for an enlargementscales
SCALE 1:X(X > 1) for a reductionscales
Drawing Scales : Designation
Drawing scale is commonly found in a title block.

24. Dimension numbersshown in the drawing represent
the “true size” of an object and they are independentof
the drawing scale used.
Drawing Scales : Notes

25. Standard reducingscales are
1:2, 1:5, 1:10, 1:20, 1:50, 1:100
Drawing Scales : Standard scale
Standard enlargingscales are
2:1, 5:1, 10:1, 20:1, 50:1, 100:1

26. Drawing Standard
Lettering
Drawing standard Contents

27. -Size (or text height)
-line thickness
-Shape
-Space between letters
-Space between words
Recommendation
Legibility
Uniformity
Text’s style on the drawing
must have the following
2 properties
Examples
GOOD
Not uniform in style.
Not uniform in height.
Not uniformly vertical.
Not uniform in
thickness of stroke.
Inappropriate space
between letters

28. Style (this course)
Gothic verticalstyle.
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 2/3of that of a
capital letter.

29. Basic Strokes
Straight Slanted CurvedHorizontal
1 1 2
3
“I” letter “A” letter
1
2
3
4 5
6
“B” letter
Examples

30. Suggested Strokes Sequence
Straight line
letters
Curved line
letters
&
Numerals
Upper-case Letters & Numerals

31. Lower-case Letters

32. I L T F
E H
Stroke Sequence : Upper-case
Skip section

33. V X W
Stroke Sequence : Upper-case
Skip section

34. N M K Z
Y A 4
Stroke Sequence : Upper-case
Skip section

35. O Q C G
Stroke Sequence : Upper-case
Skip section

36. D U P B
R J
Stroke Sequence : Upper-case
Skip section

37. 5 7
Stroke Sequence : Upper-case
1 2
Skip section

38. 6
8 9
0S 3
Stroke Sequence : Upper-case
Skip section

39. l i
Stroke Sequence : Lower-case
Skip section

40. v w x k
z
Stroke Sequence : Lower-case
Skip section

41. j y f
r
t
Stroke Sequence : Lower-case
Skip section

42. c o a b
d p q e
Stroke Sequence : Lower-case
Skip section

43. g n m h
u s
Stroke Sequence : Lower-case
Skip section

44. DRAWING
Word Composition
Non-uniform
spacing
Uniform
spacingDRAWING
Space between the letters depends on the adjacent
contour of the letters.
Word having non-uniform spacing is more readable.

45. Word Composition
Contour
DRAWING
Contour can be denoted as “straight”, “slant” and “curve”.
Adjacent contour can be
1. straight-straight : II, IN, IM, IPetc.
2. straight-curve (or curve-straight) : IO, QRetc.
3. straight-slant (or slant-straight): IV, IW etc.
4. curve-curve : OO, OGetc.
5. slant-curve (or curve-slant) : VO, WG, VCetc.
6. slant-slant : VW, VXetc.
Spacing

46. Leave the space between words equal to the space
requires for writing a letter “O”.
Example
Sentence Composition
ALLDIMENSIONS AREIN
MILLIMETERS
O O O
OUNLESS
OTHERWISE SPECIFIED.O

47. Drawing Standard
Line Types
Drawing standard Contents

48. Basic Line Types &
Name according to application
Continuous
Dash
Chain
Style
Thickness
Thick Thin
1. Dimension line
2. Extension line
3. Leader line
Center line
Hidden line
Visible line
represent features that can be seen in the current view.
represent features that can not be seenin 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

49. Example
Contents