chapter 10 convention in section - mahidol university€¦ · 3 chapter 10 conventional practice in...

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Example : Advantage of an oblique sketch

Isometric Oblique (cavalier)

Easier

Orthographic

Same effort

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RECAP

Example : Incompleted side views

Incompletedleft-side view

Incompletedright-side viewPrincipal view

Better describe an object and

facilitate dimensioning.

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Offset section : Concept & example

A section view is made by passing the bended cutting

plane completely through the part.

Example

Edge views ofthe cutting plane

are omitted

Kinds of sections

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Chapter 10

Conventional Practice in Section View

TOPICS

Section view representation

of rib, web, spoke and lug.

Aligned section

Conventional break

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Section view

representation of

rib, web, spoke and lug

TERMINOLOGY

Rib and Web are thin, flat feature of an object that

acts as a structural support.

Rib RibWeb

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Rim

Spoke is the rod radiating from the hub to the rim

of a wheel.

Spoke

Spoke

Rim

Hub

TERMINOLOGY

Hub

Lug is an ear which is built as portion of an object

for attachment.

TERMINOLOGY

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Lug is an ear which is built as portion of an object

for attachment.

TERMINOLOGY

CONVENTIONAL PRACTICE

Omit the section lines on the section view of

Rib, Web and Lug, if the cutting plane is

passed flatwise through.

Spoke, if the cutting plane is passed longwise

through.

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EXAMPLE : RIB

Normal multiview drawing

Normal section view

Section view drawing with convention

EXAMPLE : WEB : flatwise cut

Normal multiview drawing

Normal section view

Section view drawing with convention

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EXAMPLE : WEB : crosswise cut

EXAMPLE : WEB : multiple section view

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EXAMPLE : SPOKE

Misleading impression

EXAMPLE : LUG

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Aligned Section

DEFINITION

Aligned section is a section view that is drawn

by imaginary rotating the object’s features

appeared in a principal view about symmetry

axis

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Example : Hole

Gives the impression that this holes

are at unsymmetrical position.

Example : Hole

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Example : Rib

Example : Ribs & Holes

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Example : Aligned section of keywayExample : Spoke & Keyway

Example : Lug

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Conventional Break

CONVENTIONAL PRACTICE

For long objects that have to draw in a small

scale to fit them on the paper, it is recommended

to remove its long portion (which contains no

important information) and draw the break lines

at the broken ends.

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SCALE 1:1

Example

Example

SCALE 2:1

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STANDARD BREAK LINES

Rectangularcross section

Wood

Metal

Cylindricalcross section

Tubularcross section

TO DRAW CYLINDRICAL BREAK

R

R/3 R/3

30o

30o

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800

TO DIMENSION A BROKEN PART

Typicaldimensioning

method

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not to scale dimensions

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800