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Materi menggambar teknik mengenai potongan

### Transcript of Menggambar Teknik - Potongan

• 22/10/2014

1

POTONGAN

Menggambar Teknik TL

Sistematika

1. Membaca proyeksi ortogonal

2. Potongan

3. Materi Terkait Tugas

a. Skala

b. Tugas 3

MEMBACA PROYEKSI ORTOGONAL

Reading a drawing is the process of recognizing the shape of an object by interpreting the orthographic views.

DEFINITION

Orthographic Writing

• 22/10/2014

2

F.V. R.S.V

T.V.

L.S.V

B.V.

VIEWING DIRECTION

Given

Analysis by Solids

Objects are decomposed into solid geometric

primitives.

BASIC IDEA

Rectangular prism

Cylinder

Negative cylinder (Hole)

Some of familiar solid objects

Objects are decomposed into solid geometric

primitives.

BASIC IDEA

Cone

Pyramid

Sphere

Some of familiar solid objects

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3

1. Orient yourself with the views given.

(Choose the viewing direction.)

2. Read the individual surfaces that appeared in

each view and related to each other.

3. Create a proper solid geometric primitive from

4. Assembly all of solid geometric primitive

according to orthographic views.

EXAMPLE A

Given

Front View

Rectangular prism

Hole

Composition

Given

Rectangular prism

Composition

Front View

Cylinder

EXAMPLE B

Given

Cylinder with a blind hole.

Composition

L-shaped with round end

Hole

EXAMPLE C

• 22/10/2014

4

Composition

Wedge Given

EXAMPLE D Composition

Given

EXAMPLE D

L-shaped block

Wedge

Analysis by Surfaces

2. Read the individual set of lines or surface that

appeared in each view and related to each

other.

1. Orient yourself with the views given.

An understanding in orthographic projection, i.e.

meaning of lines and surfaces are almost

important.

• 22/10/2014

5

4. Repeat steps 2 and 3 until all surfaces are read.

During this repeating process, the details of

an object are added up until its completed

shape is obtained.

3. Mentally create and sketch a form of the surface

that produce the same orthographic views as

those at the beginning.

READING STEPS GUIDANCE 1

Adjacent areas that are not in the same plane must be

separated by lines.

Different plane

Line exists

Edge view

Same plane

Edge view

Top view

A

B

C

EXAMPLE

All surfaces A, B and

C are not in the same

plane.

Some of possible objects shape.

A

B C

A

B C

A

C

B

GUIDANCE 2

Areas that show a similar shape in more than one

view is the same surface.

Similar shape

• 22/10/2014

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GUIDANCE 2

Areas that show a similar shape in more than one

view is the same surface.

POTONGAN

Object

GRAPHICS COMMUNICATION

WITH ENGINEERING DRAWING

Working

drawing

Clear ?

Orthographic

projection

(convention)

Section views

convention

Section Views

Orthographic

Projection

Finish

Yes

No

Dimensioning

PURPOSES OF SECTION VIEWS

Clarify the views by

Facilitate the dimensioning.

reducing or eliminating the hidden lines.

revealing the cross sectionals shape.

Let See the example

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7

EXAMPLE : Advantage of using a section view.

ISTILAH DALAM POTONGAN

Cutting plane

CUTTING PLANE

Cutting plane line

Cutting plane is a plane that imaginarily cuts

the object to reveal the internal features.

Section lines

Cutting plane line is an edge view of the cutting plane.

CUTTING PLANE LINE

Indicate the path

of cutting plane.

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ANSI

standard

Thick line

Thick line

TS & ISO

standard

Thin line

CUTTING PLANE LINESTYLES

Viewing direction

Viewing direction

Viewing direction

This course

SECTION LINING

Section lines or cross-hatch lines are used to

indicate the surfaces that are cut by the cutting

plane.

Section lines

Drawn with thin lines.

SECTION LINES SYMBOLS

The section lines are different for each of

materials type.

Cast iron, Malleable iron

Steel Concrete Sand Wood

For practical purpose, the cast iron symbol is

used most often for any materials.

SECTION LINING PRACTICE

The spaces between lines may vary from 1.5 mm

for small sections to 3 mm for large sections.

COMMON MISTAKE

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9

SECTION LINING PRACTICE

It should not be drawn parallel or perpendicular

to contour of the view.

COMMON MISTAKE

TREATMENT OF HIDDEN LINES

Hidden lines are normally omitted from section

views.

TIPE-TIPE POTONGAN

KIND OF SECTIONS

1. Full section

2. Offset section

3. Half section

4. Broken-out section

5. Revolved section (aligned section)

6. Removed section (detailed section)

• 22/10/2014

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FULL SECTION VIEW

The view is made by passing the straight cutting

plane completely through the part.

OFFSET SECTION VIEW

The cutting plane is off-set to

include features that are not in a

straight line.

It is possible for the cutting plane

to change directions, to minimise

on the number of sectional views

required to capture the necessary

details.

OFFSET SECTION VIEW The view is made by passing the bended cutting

plane completely through the part.

Do not show the edge views of the cutting plane.

HALF SECTION VIEW A half-section is a view of an object showing one-half of the view in section. Symmetrical parts can be shown in half sections.

Half section without hidden lines

• 22/10/2014

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HALF SECTION VIEW Half sections are commonly used to show both the internal and outside view of symmetrical objects.

HALF SECTION VIEW The view is made by passing the cutting plane halfway

through an object and remove a quarter of it.

HALF SECTION VIEW A center line is used to separate the sectioned half

from the unsectioned half of the view.

Hidden line is omitted in unsection half of the view.

It is common practice to section a part of an object

when only small areas need to be sectioned to indicate

the important details

BROKEN-OUT SECTION VIEW

The example shows a broken-out sectional view to indicate a through-hole in a plate.

The lines indicating the end of the section is a thin continuous line

• 22/10/2014

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The view is made by passing the cutting plane normal

to the viewing direction and removing the portion of an

object in front of it.

BROKEN-OUT SECTION VIEW

A break line is used to separate

the sectioned portion from the

unsectioned portion of the view.

BROKEN-OUT SECTION VIEW

There is no cutting plane line.

Break line is a thin continuous

line (0.25) and is drawn

freehand.

EXAMPLE : Comparison among several section techniques

Revolved sections show cross-sectional

features of a part.

No need for additional orthographic views.

This section is especially helpful when a cross-section varies.

REVOLVED SECTION VIEW

• 22/10/2014

13

REVOLVED SECTION VIEW

Basic concept

REVOLVED SECTION VIEW

Basic concept

Given

Step 1

a. Assign position of cutting plane.

b. Draw axis of rotation in front view.

Steps in construction

REVOLVED SECTION VIEW

Edge view of cross-section

Steps in construction

Given

a. Transfer the depth dimension to

the front view.

REVOLVED SECTION VIEW

Step 2

• 22/10/2014

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Steps in construction

Given

REVOLVED SECTION VIEW

a. Draw the revolved section.

Step 3

b. Add section lines.

Steps in construction

Given

REVOLVED SECTION VIEW

FINAL PICTURE

Placement of revolved section

1. Superimposed to orthographic view.

Superimposed Break

2. Break from orthographic view.

REVOLVED SECTION VIEW 6. Removed section

Removed section is revolved section.

Used where space does not enough for revolved section

Can be located elsewhere on a drawing with properly labeled

REMOVED SECTION VIEW

Section view is shown outside the view.

It may be appropriate to use removed sections, for webs, beams or arms,

• 22/10/2014

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6. Removed section REMOVED SECTION VIEW

Note the absence of viewing arrows.

Example : Revolved vs. removed sections.

Revolved section Removed section

REMOVED SECTION VIEW

Example : Situation that rem