Week 2 Types of Line, lettering & Dimensioning..ppt

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1. By
Engr. Muhammad Arsalan Khan
Types Of Lines And Usage,
Dimensioning & Lettering.Drawing &
Graphics
7/9/2024 1

2. 7/9/2024 2a) Visible Outline
For showing visible edges of an object
b) Hidden Outline
For showing hidden edges of an object
c) Center Line
For locating center of circles, arc and ellipses relative to the object.
0.35 mm to 0.5 mm thick
0.25 mm to 0.35 mm thick
0.13 mm to 0.2 mm thick
0.5 mm to 0.7 mm thick
d) Cutting Plane Line
To show the location of the imaginary secion plane in the reference view.
2 to 2.5 mm1 to 1.5 mm
15 to 20 mm 1 to 1.5 mm2 to 2.5 mm
15 to 20 mm 2 to 2.5 mm
1 to 1.5 mm

3. 7/9/2024 3Dimension line
0.18 to 0.25 mm thick
Extension Line
0.18 to 0.25 mm thick
Terminator
0.25 to 0.35 mm thick
2 to 2.5 mm long
0.13 mm to 0.2 mm thick
0.35 to 0.5 mm thick
i) Section Lines
A pattern of thin lines 0.2 to 0.25 mm thick. The pattern and thickness is
dependent on the material.
h) Long Break Line
To show long breaks
0.35 mm to 0.5 mm thick
g) Short Break Line
For showing short breaks
f) Extension Lines, Dimension Lines and Terminators
For extension of edges and placement of dimensions.
e) Phantom Line
For showing alternate position and/or adjacent part.
1 to 1.5 mm
15 to 20 mm
0.13 mm to 0.2 mm thick
2 to 2.5 mm
73

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7. 7/9/2024 7

8. 1.NEEDFORLETTERING
Letteringisneededfor
•Dimensionsofparts
•Notesrelatingtothemanufactureofparts
•Descriptivetitles.
Shallbe
•Highlylegible
•Uniform
•Capableofbeingdonerapidly

9. 2.CONSIDERATIONS FORGOODLETTERING
A.GeneralProportions
•Nospecificstandardfortheproportionsofletters
•Proportionofwidthtotheheightoflettersvaries.
B.TheRuleofStability
•Inordertogivetheappearanceofstability,lettersasB,E,K,S,X,
andZandthedigits3and8mustbedrawnsmalleratthetopthanat
thebottom.
C.GuideLines
•Alwaysdrawlightguidelinesforbothtopsandbottomsofletters.A
verysharppencilshallbeusedforthepurpose.

10. D.StylesofLettering
•Nospecificstandardforthestyleoflettering
•Stylesshallbesimpleandcleartofacilitatethereadingofadrawing.
•TIME-CONSUMINGLETTERINGSTYLEshouldbeavoided.
•ANEFFICIENTLETTERINGSTYLE
•ALIMITED-USELETTERINGSTYLE
E.SizeofLettering
•Shallbeatleast0.125in(3.00mm)high
F.AspectRatio
•Thewidth/heightratio
•Nospecificstandard

11. 1.PURPOSEOFDIMENSIONING
•Toprovideexactinformationonthesizeandpositionofeachfeature
ofthepartforproductionpurposes.
2.SIZEVS.POSITIONDIMENSIONS
•Dimensionscanbeclassifiedasthoseforsizeorposition.
•Eachfeatureshallbedimensionedandpositionedonlyonce.
•Eachfeatureshallbedimensionedandpositionedwhereitsshapeis
shown.

12. P P
PS
S
P
S
S Drill, 2 holes
SR
(S)
S
S
S
Dimensions of size and position. S indicates size, P position

13. 3.BASICEXAMPLESOFDIMENSIONSOFSIZEANDPOSITION
Eachofthegeometricshapesmakinguptheobjectmusthaveitsheight,
width,anddepthindicatedinthedimensioning.
a.Prism
•Themostcommonshape
•Requiresallthethreedimensions(forbaseandlength)60 45
45

14. 1.USEOFSCALE
•Apartmaybedrawntoanyconvenientscale.
•Thescalemustbeindicatedinaneasilyseenareaoftheworkingdrawing,
ofteninthetitleblock.Ifasheetofdrawinghasmorethanonescale
used,thenthescaleshallbementionednexttotherelevantview.
•Thedimensionsplacedonthepartarealwaysactualsizedimensions.

15. 2.DIMENSIONSANDNOTES
•Distancescanbegivenaseitherdimensionsornotes.
•Specificnoteshavealeaderandshallbeplacedclosetothefeatureto
whichtheyapply.
•Generalnotesdonotrequirealeaderandshouldbegroupedtogether
abovethetitleblock.50
R15
Ø12 Drill

16. 3.EXTENSIONLINESANDLEADERS
A.ExtensionLines
•Shallnottouchtheoutlineoftheview.Thereshallbeanoffsetof
about1.5to2mmfromtheorigin.
•Shallextend2.5to3mmbeyondthelastdimensionline.
•Dimensionsmayalsoterminateatcenterlinesorvisibleoutlinesof
theview.
•Centerlinesareextendedtoserveasextensionlineswherethe
distancebetweencentersistobeshown.
•Extensionlinesforanangulardimensioncanbeusedtoplacelinear
dimensions.
•Extensionshallnotbebrokenwheretheycrosseachotheroran
outlineofaview.Whenspaceisrestrictedandextensionlinescome
closetoarrowheads,theextensionlinesmaybebrokenforclarity.
•Whereapointislocatedbyextensionlinesalone,theextensionlines
shouldpassthroughthepoint.

17. 65
18
50
50
20
45

18. A.Leaders
•Leadersarestraight(notcurved)linesleadingfromadimensionvalue
oranexplanatorynotetothefeatureonthedrawingtowhichthenote
applies.
•Arrowheadisusedatthepointingendoftheleader.
•Shallbedrawnatanangletotheprincipallinesofthedrawing.
•Adotsometimesmaybeuseforterminationofaleader.
•Forcircularfeatures,leadershallberadial.
•Avoidlongleadersorcrossingleaders.3 x 45°
CHROME

19. 4.LINEWEIGHTSANDARROWHEADS
•Lineweightsforthedimensionlinesandextensionlinesshallbe0.2mm
to0.25mm.
•Arrowheadsshallbedarkerinappearancethantheextensionlinesand
dimensionlines.Bothopen30
o
andclosedfilledcanbeused.
•Arrowheadsshallbeabout3mmlongandshallhaveaconsistentsize
andappearancethroughoutthedrawing.
5.DIMENSIONTEXT
•Dimensiontextshallbeabout3mmhigh.
•IntheBSIandANSImethodsthetextisplacedhorizontalbetweenthe
dimensionline.
•IntheISOmethodsthetextisalwaysplacedabovethedimensionline.
Thetextmustbealignedtothedimensionlineifitiswrittenbetweenthe
extensionlines.Ifhowever,itiswrittenoutside,thenitshallbehorizontal.
•IntheBSIandANSImethods,ifarrowsareplacedoutside,then
dimensionlineshallnotbedrawnbetweentheextensionlines.
•IntheISOmethods,thedimensionlineshallalwaysbedrawn.

20. 205.5
5.5
20.5
1
1
4
1
4
5
16
1
7
32

21. These topics can also be covered from Engg.
Drawing book, Chapter 3.