Engineering Graphics

7/17/2019 Engineering Graphics

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1SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

Engi 1504 – Graphics

Lecture 6: Descriptive Geometry

Properties of lines

Properties of planes

u!iliary planes "i#term hints

$lass assignment 6

http://www.tekniksipil.org/civil-engineering



"SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

Points an# Lines

#he point is the $asic $uil!ing $loc% for an

o$&ect'



(SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

Points an# Lines

Stan!ar! notation

) AF is the vie of point A on the frontal plane

) #he height* i!th* an! !epth are specifie! ith

reference to the reference +fol!ing lines,




Points an# Lines

Note: ) The distance behind a plane (say the front plane) is seen in all

other adjacent views.

) If the distance to point A from the folding line is known in oneadjacent view, point A can be located in another adjacent view




Lines

- line is ma!e up of to points ( vies of line -. are shon



/SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

Lines ertical line ) shos as a

point in top vie* parallel

to front an! right si!e

planes

ori2ontal ) infinite

positions* $ut all points

must have e3ual elevation



SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

Lines ncline! line ) parallel to

front or right plane'

-lays parallel to one

plane an! incline! to the

others

6$li3ue line ) incline! to

all principal planes




u!iliary Planes

#he length of a line can only $e measure! if it

is seen in true length

8ecall: - line can $e seen true length if

pro&ecte! onto a plane parallel to it So to fin! the true length of a line e !ra an

au9iliary fol!ing line parallel to it'



SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

u!iliary Planes

Consi!er the front an!top vie of o$li3ue line

ab

;e can !ra anau9iliary plane parallel to

either line aFbF or aHbH




u!iliary Planes

-u9iliary planeparallel to line

aHbH

#he line isperpen!icular to

hori2ontal +top,

vie

"

"

1

1

#<




Point %ie& of a line

8ecall: - line can $e seen as a point ifpro&ecte! onto a plane perpen!icular to it

So an au9iliary plane perpen!icular to a linethat shos true length ill sho as a point'

Note: to sho line as a point* nee! a viethat shos true length first'



1"SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

Point %ie& of a line

8ecall: - line can $e seenas a point if pro&ecte! onto aplane perpen!icular to it

So an au9iliary planeperpen!icular to a line thatshos true length ill shoas a point'

Note: to sho line as apoint* nee! a vie thatshos true length first'

=(

=(

ao$o

- 6



1(SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

'lope of a line

#he slope +or gra!e, of a line is the inclinationof the line ith the hori2ontal

Slope can $e measure! in a vie that shos

vertical height an! the line in true length So e !ra a fol!ing line in the hori2ontal

+top, vie'




'lope of a line

So e nee! anau9iliary vie +fol!e!from the top vie,* thatshos the line as truelength

Slope is the angle$eteen the true lengthline an! a line parallelto the fol!ing line




Direction of a line

#he !irection of a line +givenas a compass rea!ing, isseen only in the top vie'#hin% of hol!ing a compass'

- $earing is measure! fromeither north or south* ith

north usually at top of page -2imuth is measure! from

north an! specifie! as anangle from 0>(/0?

.earing

-2imuth



1/SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

'ummary

@in! true length of a line:1' Alace an au9iliary vie parallel to the line an! pro&ect to points

on the line onto the au9iliary vie

@in! point vie of a line:1' Nee! a true length line first

"' <ocate an au9iliary vie perpen!icular to the true length line an!pro&ect en!points

@in! slope of a line1' Nee! a true length line an! an e!ge vie of the hori2ontal

"' @in! an au9iliary vie +fol!e! off the top vie, that ill sho truelength




'ummary $ontinue# (

#hings to remem$er a$out lines: f a line is parallel to a fol!ing line* it ill appear true length in

the a!&acent vie .earing an! a2imuth are seen only in the plan +top, vie f to lines intersect* the intersection point ill correspon! in

all vies #he shortest !istance $eteen to lines is seen here one of

the lines appears as a point Aerpen!icular lines appear perpen!icular in any vie in hich

one or $oth of the lines appear in true length

- line ill appear true length in any vie fol!e! off a pointvie of the line'




)rea* +ime

#a%e 5 minute $rea%




"i#term ,ints an# +opics

Mi!term e9am is Novem$er 1st <ectures 1>5 are covere! +Chapters 1>4 in

te9t, 8evie your assignments 8evie visuali2ation e9ercises Aractice as many pro$lems as you can Contact me if you are stuc%' My office hours

are 1>" pm on #ues!ays +EN (0((, Stu!ent Buestions



"0SheetCourse: Engineering Graphics 1504 Memorial University of Nefoun!lan!

$lass ssignment -6

Aoint A is ! m $ehin! the frontal plane an!

"# m $elo the hori2ontal plane' Aoint $ is ""

m $ehin! the frontal plane an! % m $elothe hori2ontal plane' #he line A$ $ears N /5?

E' Using an appropriate scale !ra a point

vie of line A$'

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Engineering Graphics