Mechanics

Level-III
Based on March 2022, Curriculum Version 1

Module Title: Geometric Development

Module Code: IND MCS3 M02 1023
Nominal Duration: 60Hour

Prepared by: Ministry of Labor and Skill

October, 2023
Addis Ababa, Ethiopia
 Table of Content
Acknowledgment ........................................................................................................................... 4
Acronym......................................................................................................................................... 5
Introduction to the Module .......................................................................................................... 6
Unit One: Marking and Measurement ...................................................................................... 7
1.1 Introduction to Geometric Development.......................................................................... 8
1.2 Work Requirements............................................................................................................... 8
1.3 Marking Outs......................................................................................................................... 8
Self-check .................................................................................................................................. 11
Unit Two: Pattern Templates .................................................................................................. 13
2.1 Introduction to Templates ................................................................................................... 14
2.2 Template Materials .............................................................................................................. 14
2.3 Template Making ................................................................................................................ 15
2.4 Safety for Template ............................................................................................................. 15
Self-check .................................................................................................................................. 16
Operation Sheet 2.0: .................................................................................................................. 17
LAP Test ................................................................................................................................... 19
Unit Three: Patterns Development......................................................................................... 20
3.1 Development of Surfaces .................................................................................................... 21
3.2 Importance of Development ................................................................................................ 21
3.3 Tools and Materials ............................................................................................................. 21
3.4 Methods of Development .................................................................................................... 24
Self-check .................................................................................................................................. 26
Operation Sheet 3.0: .................................................................................................................. 27
Operation Sheet 3.1: .................................................................................................................. 29
Operation Sheet 3.2: .................................................................................................................. 30
LAP Test ................................................................................................................................... 33
Unit Four: Material Quantity Estimation ................................................................................ 34
4.1 Introduction to Estimation................................................................................................... 35
4.2 Quantity Estimation from Development ............................................................................. 35
4.3 Material Optimization ......................................................................................................... 35

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Self-check 1 ............................................................................................................................... 37
Operation Sheet 4.0 ................................................................................................................... 38
LAP Test ................................................................................................................................... 40
List of References...................................................................................................................... 41

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 Acknowledgment
Ministry of Labor and Skills wish to extend thanks and appreciation to the many
representatives of TVT instructors and respective industry experts who donated their time and
expertise to the development of this Teaching, Training and Learning Materials (TTLM).

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 Acronym -

- TTLM-Teaching, Training and Learning Material.

- TVT– Technical and Vocational Training.
- LAP- Learning Activity Performance.

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 Introduction to the Module
Geometric Development is an advanced module on the fundamentals of pattern development
used in some forms of sheet metal works in TVT Institutions. It is a short briefing on the basics
of Transfer measurements, pattern development, and template makings. This module is designed
to meet the industry requirement under Mechanics Occupational Standard, particularly for the
unit of competency: Perform Geometric Development.
This module covers the units:-
 Marking and Measurement
 Pattern Templates
 Pattern Development
 Material Estimations
Learning Objective of the Module:-
 Mark off/out fabrications
 Make templates as required
 Develop patterns as required
 Estimate quantities of materials from detail drawings
Module Instruction
For effective use this modules trainees are expected to follow the following module instruction:
1. Read the information written in each unit.
2. Accomplish the Self-checks at the end of each unit.
3. Perform Operation Sheets which were provided at the end of units.
4. Do the “LAP test” given at the end of each unit.
5. Read the identified reference book for examples and exercise.

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 Unit One: Marking and Measurement
This unit is developed to provide you the necessary information regarding the following content
coverage and topics:-
 Introduction to Geometric Development
 Work Requirements
 Marking Outs:-
This unit will also assist you to attain the learning outcomes stated in the cover page.
Specifically, upon completion of this learning guide, you will be able to:
 Identify Work Requirements for development
 Perform Marking Outs
 Identify datum points
 Identify Marking Tools

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1.1 Introduction to Geometric Development
A geometric development (pattern development) is defined as a stretch out of an object on a flat
surface. To obtain a pattern of a given body, we need to cut it along one, two or more of its edges
so that it can be stretched on a flat surface. The concept of pattern development plays a vital role
in sheet metal work. A development is the unfold/ unrolled flat / plane figure of a 3-D object,
Called also a pattern, the plane may show the true size of each area of the object. When the
pattern is cut, it can be rolled or folded back into the original object. A wide variety of packing
materials are also prepared from carton using the concept of pattern development.

1.2 Work Requirements

Since sheet metals are expensive, it is important that students make practice using hard paper
(Classer). After they have grasped the basic knowledge of pattern development they move on to
actual sheet metal process. So this course is divided in to two major parts: Pattern practice using
hard paper and actual work using sheet metal.
The first part can be held in a standard drawing room where students draw the given pattern on
hard paper, then cut-off the pattern, make the necessary forming and finally join the edge using a
paper glue (UHU).
The importance of this part is tremendous.

1. Hard paper is easily manageable than sheet metal

2. Sheet metal Wastage is minimized
So pattern practice using hard paper is basically a technical drawing except the cutting, forming
and joining process involved. All drawing instruments needed for technical drawing are
employed. For this reason drawing instruments and their function is revised in this learning
material.

1.3 Marking Outs

Marking out is defined as a process of transferring a design, layout or dimensions from the
drawing to a work-piece, and it is considered as the first step in the manufacturing process.
Marking out and measuring is a critical part of manufacturing and is usually subject to a number
of quality control checks. If components are marked out and measured wrongly, confirm before
being cut out, there is no chance of them fitting together when they are assembled.
Always take marking out measurements from a datum. A datum edge is a flat face or straight
edge from which all measurements are taken. This prevents cumulative errors being made.

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1.3.1 Datum Point

A datum point refers to a reference point from which you start a drawing. So the main thing you
need to understand here is that you can’t start a drawing from anywhere you like. If you do so
you will find down the road that your drawing goes out of paper boundary or work piece
boundary. Such problems usually arise in triangulation method. The concept behind a datum
point is that you should always know the size of your paper (work piece) and the size of a figure
you are going to draw. Then you have to start your drawing from some suitable place so that it
properly fits in to the paper (work piece). Specially during examinations such kind of error will
nullify your result because you may not get enough time to start the work from scratch once
again.

1.3.2 Marking Tools

The common marking out tools used in geometric developments are: Scribers, Punch, Tri-
squares, Dividers, Steel rule and etc…
1. Scribers

A scriber is a piece of steel wire having a hardened sharp point to draw lines. A sharp-pointed
tool used for making marks & especially for marking off material to be cut.

Figure 1.1 Straight and Bent Edges Scribers

2. Center Punch

A punch is a hard metal rod with a shaped tip at one end and a blunt butt end at the other, which
is usually struck by a hammer. Most woodworkers prefer to use a ball-peen hammer for using
punches. Punches are used to drive objects, such as nails, or to form an impression of the tip on a
work piece. Decorative punches may also be used to create a pattern

Figure 1.2 Center Punch

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 3. Try-Square

Try square is used for making and testing angles of 45o and 90o. A try square is a metal
working tool used for marking and measuring a piece of metal. The square refers to the tool's
primary use of measuring the accuracy of a right angle (90o); to try a surface is to check its
straightness or correspondence to an adjoining surface.

Figure 1.3 Try-Square

4. Dividers

Divider: This is used for marking circles, arcs, laying out perpendicular lines, bisecting lines,
etc…

Figure 1.4 Dividers

5. Steel Rule
Steel Rules, also known as Steel Rulers or machinist rules, are precision measuring tools used to
measure length, width, or depth of objects in mechanical, machining, and woodworking
applications.

1.3.2 Marking Allowances

Marking allowances are essential considerations in the field of manufacturing and pattern
development. These allowances refer to the intentional deviations made in the dimensions of a
pattern marking from the final desired dimensions of a finished product. Allowances may include
for bending and seams, bearing in mind the thickness of material used.

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Self-check
Directions: Answer all the questions listed below. Use the Answer sheet provided by your
trainers:

Part I: Multiple Choices

A) Choose the correct answer from the following Questions

1. _________ is used for making and testing angles of 45o and 90o.
A. Dividers B. Try square
C. T-square D. Punch
2. Which one is used to make marking on metals to be cut.
A. Punch B. Divider
C. Scribers D. Try squares
3. ___________ refers to a reference point from which you start a drawing.
A. Surface plate B. Bench
C. Edges D. Datum point

Part II: Matching

B) Match column ‘A’ with Column ‘B’

A B
_____ 1. Process of transferring measurement A) Datum edge
_____ 2. Flat / straight edge B) Allowances
_____ 3 Steel Rule C) Hard paper
_____4. Intention deviation D) Steel rule
_____5. Pattern material E) Marking out
Part III: True/False

________1, A geometric development (pattern development) is defined as a stretch out of an

object on a flat surface.
________2, Pattern practice is done using hard paper and actual work using sheet metal.
________ 3. After they have grasped the basic knowledge of pattern development they move on
to actual sheet metal process.

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Part IV: Explain

1. Explain about geometric development.

2. List types marking tools that are used for geometric development
3. Why work requirement is important in geometric development?
4. What is the difference between try square and Set square?
5. Why we use marking allowances

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 Unit Two: Pattern Templates
This unit to provide you the necessary information regarding the following content coverage
and topics:-
 Introduction to Templates
 Template Materials
 Safety for Template
 Template Making
This guide will also assist you to attain the learning outcomes stated in the cover page.
Specifically, upon completion of this learning guide, you will be able to:
 Identify Materials for Template
 Safety for Template
 Perform Template Making

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2.1 Introduction to Templates
Template is shaped piece of rigid material used as a pattern for processes such as cutting out,
shaping, or drilling, something that serves as a model for others to copy.
Anything used for duplicating a geometric figure is said to be a template. The figure may be a
circle, a rectangle, square, polygon etc. But the function of a template is not limited to the above
simple geometries. In manual production and assembly, an enterprise can develop its own
template from which it can duplicate hundreds and perhaps thousands of identical items. In
geometric development, in particular, a complicated pattern can easily be duplicated from a
template repeatedly with accurate dimensions.
When it comes to geometric development in particular the question is put to every step of the
process. What are the things we need to improve with respect to pattern development lay out,
cutting, forming and joining so as to produce items with the right quality, right quantity and
deliver on time. In general, the importance of a template is:-
 to save time and energy,
 duplicating a pattern from a template does not require great skill,
 greater dimensional accuracy,
 promotes standardization,

Figure 2.1 Sheet Metal Templates

2.2 Template Materials

A template may be made from paper, hard plastic, and sheet metal, wood or metallic plate. The
material from which we make a template depends up on the quantity of item to be duplicated
from the template and the duration over which the template is supposed to serve. In a situation
where quantity is very low and we don’t expect to make the same pattern in the future, we
mostly use paper template. Sheet metal or metallic plates are used when production quantity is
high or whenever we expect the same order to come for a long time in the future.

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 2.3 Template Making
While making a template the first thing we need to do is to choose a template material based on
the criteria listed above. Then on the material we have chosen we draw the pattern accurately to
scale. Then we cut-off the pattern leaving a hole in the template. Finally we add allowances on
every side of the figure to allow for clamping and handling.

2.4 Safety for Template

To make a single template we usually sacrifice time, skill, tools and machines. It means that
templates are costly items. So care is needed at all times so that they will not be damaged. The
dimensions we transfer from damaged templates are usually wrong and not the same. To avoid
damage of templates, the following rules should always be observed
 Transfer dimensions with care not to damage template holes and edges
 After use return the template

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Self-check
Directions: Answer all the questions listed below. Use the Answer sheet provided by your
trainers:

Part I: Short answer and Explain

1. _________ may be made from paper, hard plastic, and sheet metal, wood or metallic
plate.
2. Why templates are important in pattern development?
3. List all template materials used in development.
4. Allowances are added on pattern template. Why?
5. What is the importance of safety?

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Operation Sheet 2.0:
Operation title: Pattern Template making
Purpose: To practice how to make Pattern template.
Instruction: Use the given tools and equipment, perform the tasks given below.
Tools and requirement:
 Hard Paper/Thin Sheet metal/
 Steel Rule
 Set square
 Drawing pencil/Marker
 Dividers
 Cutters
Precautions: For every practice use the required tools and accuracy of your work is mandatory.
Procedures
The figure below shows a 90x30x50 box. Prepare a template of the box from hard paper using
the given dimension.

1. Here the object is a box in which the bottom becomes part of the development. So to
make the development we cut the box along all the four edges and then stretch it on a flat
surface. Doing so we get the following

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 2. Now it is time to think about joining method. The material from which you make the
object determines joint design and amount of allowance required. To prepare the box
from hard paper you may use an allowance of 10mm on all sides as shown below.

3. Cut-off the pattern and leave a hole in the work piece get a template as shown below.

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LAP Test
Instruction: Given necessary tools and materials you are required to make templates for the
following tasks.
Task 1:

Task 2:

Task 3:

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 Unit Three: Patterns Development
This unit to provide you the necessary information regarding the following content coverage
and topics:-
 Development of Surfaces
 Importance of Development
 Tools and Materials
 Methods of Development
This guide will also assist you to attain the learning outcomes stated in the cover page.
Specifically, upon completion of this learning guide, you will be able to:
 Identify Development of Surfaces
 Understand Importance of Development
 Identify Tools and Materials
 Identify Methods of Development
 Develop Different Surfaces

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3.1 Development of Surfaces
In industrial, world an engineer is frequently confronted with problems where the development
of surfaces of an object has to be made, to help him to go ahead with the design and
manufacturing processes. For example, in sheet metal work, it plays a vital role, thus enabling a
mechanic to cut proper size of the plate from the development and then to fold at proper places to
form the desired objects, namely, boilers, boxes, buckets, packing boxes, chimneys, hoppers, air-
conditioning ducts etc.
The development of surface of an object means the unrolling and unfolding of all surfaces of the
object on a plane. When the complete surface of a solid is opened out and laid on a plane, the
surface of the solid is said to have been “developed” and the figure obtained is called
“development” of the surface. Every line on the development must be true length of the
corresponding line on the surfaces.

Figure 3.1 Developments of Surfaces

Many articles such as cans, pipes, elbows, boxes, etc. are manufactured from thin sheet
materials. Generally a template is produced from an orthographic drawing when small quantities
are required, and the template will include allowances for bending and seams, bearing in mind
the thickness of material used.

3.2 Importance of Development

Knowledge of development is very useful in sheet metal work, construction of storage vessels,
chemical vessels, boilers, and chimneys. Such vessels are manufactured from plates that are cut
according to these developments and then properly bend into desired shaped. The joints are then
welded or riveted. Every line on the development should show the true length of the
corresponding line on the surface which is developed.

3.3 Tools and Materials

The common tools and materials that we use in pattern developments are discussed below:

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 1. Drawing Board - There is perfectly straight projecting edge on one side of the board
known as working edge, which is useful when T-square is used in the pattern
development.

Figure 3.2 Drawing Board

2. T-square
T-square is provides a parallel straight edge for the beginning drawing drafter. It is composed of
two parts: the head and the blade used to draw straight line and to support set squares to draw
line at different angles.

Figure 3.3 T-Square

3. Triangles (Set- square)

Triangles (setsquares):- They are used to construct the most common angles (i.e. 30o, 45o,
and 60o) in technical drawings. The 45o x 45o and 30o x 60o triangles are the most commonly
used for ordinary work.

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 Figure 3.4 (a) 30|60 Set Square (b) 45 Set Square

4. Compass

Drawing compass has two parts connected by a hinge so the radius of the circle that is drawn
can be adjusted and changed. Usually at the end of one part is a needle and at the end of
another is a pencil and used to draw circles and circular arcs.

Figure 3.5 Compasses

5. Drawing Paper

They are available in many varieties and good quality paper with smooth surface should be
selected for Drawings which are to be preserved for longer time. Recommended Standard size of
drawing sheet.

6. Drawing Pencils:
The accuracy and appearance of a Drawing depends on the quality of Pencil used to make
Drawing.
7. Eraser
Erasers are made of plastic rubber and used to correct drawings drawn by drawing pencils.

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3.4 Methods of Development
There are four methods of pattern development:

1. Parallel-line development
2. Radial-line development
3. Triangulation development
4. Approximate development

1. Parallel-Line Development

Parallel line development is used to develop patterns of square, rectangular and cylindrical
shapes (prisms). The method divides the surface into a series of parallel lines to determine the
shape of a pattern.
Application: Parallel line development is used for the pattern development of pipe work, prisms,
and any cylindrical shape.
Pattern development can be marked directly onto flat metal plate. The metal is then formed to
shape. Patterns are often turned into templates using paper or thin sheet steel. On formed stock
pipe, the pattern becomes a wraparound template, and can be used over and over again.

Figure 3.6 Parallel-line Developments

2. Radial-line Development

The radial line method of pattern development is used to develop patterns for objects that have a
tapering form with lines converging to a common point, called the apex point.
The radial line method uses a series of radial generator lines drawn from a common apex point to
develop a specified pattern or shape.
It is employed for Pyramids and single curved surfaces like Cones in which the apex is taken as
center and the slant edge or generator as radius of its development.

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 Figure 3.7 Radial-line Developments

3. Triangulation Development

It is used for developing transition pieces.

 Transition pieces are usually made to connect two different forms, such as round pipes to
square pipes.
 This is done by assuming the surface to be made from a series of triangular surfaces laid
side-by-side to form the development.
 This form of development is known as Triangulation.

Figure 3.8 Triangulation and Transition Developments

4. Approximate Development

Approximate developments are used for double curved surfaces, such as spheres.
Approximate developments are constructed through the use of conical sections of the object.
The material of the object is then stretched through various machine applications to produce the
development of the object.

Figure 3.9 Approximate Developments

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Self-check
Directions: Answer all the questions listed below. Use the Answer sheet provided by your
trainers:

Part I: Matching

Match column ‘A’ with Column ‘B’

A B
_____ 1. Approximate developments A) T-square
_____ 2. To draw standard and other angles B) Compass
_____ 3. Used to support set squares C) Apex
_____4. Common point of cone D) Sphere
_____5. Used to draw circles and circular arcs E) Set squares
Part II: True/False

________1, Approximate developments are constructed through the use of conical sections of
the object.
________2, Many articles such as cans, pipes, elbows, boxes, etc. are manufactured from hard
plate materials..
________ 3. Pattern development can be marked directly onto flat metal plate.
________ 4. Spheres are developed by using radial line development.
________ 5. The edges of every cone is always a true length.
Part III: Short Answer/Explain

1. Why development is important in manufacturing industry?

2. What knowledge is/are required to perform development?
3. List tools and Material that are used for development of surfaces.
4. Which development method is used to develop transition pieces.
5. What is True Length in development?

Part IV: Write Short Note on The Following Development methods

1. Parallel-line development
2. Radial-line development
3. Triangulation development
4. Approximate development

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Operation Sheet 3.0:
Operation title: Parallel-Line development
Purpose: To practice how to develop Pattern in parallel line.
Instruction: Use the given tools and equipment, perform the tasks given below.
Tools and requirement:
 Drawing board
 Paper
 T-square
 Set square
 Drawing pencil
 Erasers
Precautions: For every practice use the required tools and accuracy of your work is mandatory.
Procedures
1. Draw a full plan (top) and elevation view (front) of the project, complete with
the center line.

2. Divide the top view into 12 equal parts (see Divide a Circle into 12 Equal Parts) and label
it. It is common practice to label a round object with numbers.

3. Project the plan view divisions down into the elevation view.

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 4. Draw the stretch-out directly to the right of the elevation view and divide it into 12 equal
parts (see Divide a Line Using a Ruler on an Angle). Label it to match the plan view and
make sure to start the labeling where you want the seam. Add any required seam
allowances outside of the stretch-out.

5. At the points where the element lines cross the miter line, project them into the stretch-
out.

6. Following the labeling, circle the intersection points on the stretch-out. Don’t put a dot
over the points, but circle around them.
Using a flexible curve, join the points to draw in the miter line, completing the pattern.

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Operation Sheet 3.1:
Operation title: Radial-Line development
Purpose: To practice how to develop Pattern in Radial line.
Instruction: Use the given tools and equipment, perform the tasks given below.
Tools and requirement:
 Drawing board
 Paper
 T-square
 Set square
 Drawing pencil
 Erasers
Precautions: For every practice use the required tools and accuracy of your work is mandatory.
Procedures
The steps involved in right circular cones
1. Draw a circle with a radius equal to the slant height.

2. Divide the base circle of the cone in to 12 equal parts

3. Using a compass transfer each division point to the circle you have drawn in step #1
above

4. A region with a solid boundary is the pattern of the cone

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Operation Sheet 3.2:
Operation title: Development of Transition pieces
Purpose: To practice how to develop Pattern in Transition piece.
Instruction: Use the given tools and equipment, perform the tasks given below.
Tools and requirement:
 Drawing board
 Paper
 T-square
 Set square
 Drawing pencil
 Erasers
Precautions: For every practice use the required tools and accuracy of your work is mandatory.
Procedures
Steps to develop a Square to Round

1. A true understanding of what "True Length" means and how to find and see true lengths
is everything in pattern development by means of triangulation. Here we take you step by
step in developing a Square to Round, just keep in mind "Practice makes perfect".

2. Take a look at how we got started, before you can begin to layout your pattern you have
to find all your true lengths. The only way you can see a true length line is perpendicular
to its plane, the best way to see the true lengths in a square to round fitting is to draw a
top view of the fitting as we did above.
You need to develop a true length bar. Using your dividers or trammel points, transfer
from your top view points A1, A2, A3, A4, A5, A6, B6 and B1. Making sure to mark
each one.
Draw a line from the top of your True length bar (which must be the total height of your
fitting) down to each reference mark on the base of your true length bar.

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 3. Take the dimension A to A from your top view and draw a straight line.
Set you dividers to dimension A to B and draw a small arch as a reference point. Once
your dividers are set, place one end on A and make a reference mark as we did in Fig.1
(you will need to do this with each side.

4. Set your dividers on points 6,5 in your top view and transfer this dimension to your
drawing as we did in Fig.2

Set your dividers to the A5 length from your true length bar and make a reference mark
that intersects with 6,5 reference mark.
Reset your dividers to the distance of 5,4 from your top view and transfer this to your
drawing.

5. Continue what you were doing in Fig.2 until you have all A6 through A1 lines
transferred. Does your drawing look like Fig.3?

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 6. Determining line B1. We know from our top view that B is half the distance from A to A
and we referenced this with an arch. Now we need to transfer line B1 from our true
length bar by setting your dividers to that distance and transferring it by placing one end
on point 1 and drawing an arch across the arch we labeled B. The intersection of these
two arch's becomes point B.
Draw a line from point 1 down to point B and draw another line from point A to point B 2 pieces
required to make one fitting

One last thing to do is to connect the points 1 through 6. We did not add allowance for
any seams or overlaps

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LAP Test
Instruction: Given necessary tools and materials you are required to perform the following
tasks.
Task 1: Perform Parallel line development for:

1. Cylinder of Dia.40mm and height of 60mm.

2. A truncated cylinder of Dia.40mm and truncated at 45o from height of 40mm.
3. A rectangular prism of 60mm x 80mm x 25mm.
4. A truncated square prism of 40mm x 40mm and truncated at 45o from height of
40mm.

Task 2: Radial line development for:

1. A frustum of cone of bottom Dia.40mm and upper Dia, 20mm and height of
60mm.
2. A square pyramid of base 40mm x 40mm and height of 60mm.
3. A truncated cone of Dia. 40mm and truncated at 30o from height of 35mm.

Task 2: Transition piece development for:

1. Square to round transition of 50mm x 50mm base and upper diameter of round part
is 30mm at the height of 60mm.
2. Square to hexagon transition of 60mm x 60mm base and dia, of circumscribed circle
for upper hexagon is 40mm.

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 Unit Four: Material Quantity Estimation
This unit to provide you the necessary information regarding the following content coverage
and topics:-
 Introduction to Estimation
 Material Quantity
 Material Optimization
This guide will also assist you to attain the learning outcomes stated in the cover page.
Specifically, upon completion of this learning guide, you will be able to:
 Identify Quantity or blank size
 Estimate Material Quantity from Drawing/Development
 Optimize Material Usage

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4.1 Introduction to Estimation
Estimation or estimating is the process of calculating the quantities of various items of works
involved in the pattern. Estimating, in general, implies indication of a carefully considered
computation of some quantity, the exact magnitude of which can not be determined at that stage.
Blank size determination refers to a way of estimating blank size required to make a particular
development project. The project can be any simple pattern development students make in a shop
or any real project associated with it.

4.2 Quantity Estimation from Development

The quantity of material in a pattern can be accurately determined from the drawings. The
estimator must review each sheet of the drawings; calculate the quantity of material. Quantity
calculations beyond design details are often necessary too.
Finally we add an allowance which the student needs to make the layout. The allowance we add
at this stage depends up on,
1. The complexity of the figure.
2. The students ability to choose proper datum point.

4.3 Material Optimization

Optimizing materials use and minimizing waste Recycling is a process to change waste materials
into new products to prevent waste of potentially useful materials, reduce the consumption of
fresh raw materials, reduce energy usage, and reduce air pollution and water pollution by
reducing the need for "conventional" waste disposal. Recycling is a key component of modern
waste reduction and is the third component of the "Reduce, Reuse and Recycle" waste hierarchy.
Recyclable materials include many kinds of glass, paper, metal, plastic, textiles, and electronics.
The Materials to be recycled are either brought to a collection center or picked up from the
curbside, then sorted, cleaned, and reprocessed into new materials clear for manufacturing.
Reuse- is to use an item again after it has been used. This includes conventional reuse where the
item is used again for the same function and new-life reuse where it is used for a different
function. In contrast, recycling is the breaking down of the used item into raw materials which
are used to make new items.
Waste minimization involves: -
 redesigning products

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  changing common patterns,
 Waste minimization concerning about the consumption and
 Production of material, to prevent the creation of waste.

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Self-check 1
Directions: Answer all the questions listed below. Use the Answer sheet provided by your
trainers

Part I: Answer the following questions

1. Define how we can estimate quantities from Drawing?

2. Explain what is Blank size determination?
3. Write the steps involved in blank size determination.
4. What are the advantages of Material optimizations?
5. What we mean by blank size?

Page 37 of 42 Ministry of Labor and Skill Version -1

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Operation Sheet 4.0
Operation title: Determining blank size for the given Pattern
Purpose: To practice how to determine blank size for the given Pattern.
Instruction: Use the given tools and equipment, perform the tasks given below.
Tools and requirement:
 Drawing board
 Hard Paper
 T-square
 Set square
 Drawing pencil
 Cutters
Precautions: For every practice use the required tools and accuracy of your work is mandatory.
To include any form of allowance the student needs to make layout.
Procedures
The steps involved in blank size determination include,
1. To draw the pattern accurately to scale,
2. To include any form of allowance needed to join the edge,
The figure below shows a simple 90x30x50 box.

 The pattern of the box given above when developed is given as follows.

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  So once we have the pattern accurately drawn to scale, the next task will be to add
allowances needed for joining. For this particular pattern we can add an allowance of
10mm as shown below.

 Next we find the dimension of the smallest rectangle which can engulf the figure above
which taken as blank size.

Page 39 of 42 Ministry of Labor and Skill Version -1

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Author/Copyright October, 2023
LAP Test
Instructions: Given necessary tools and materials, Determine the blank size needed to make the
project from hard paper.
Task 1:

Task 2:

Task 3:

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List of References

1. Hajra Choudhory C.J., "Elements of workshop Technology ", Vol. I to Vol. III, Asia
Publishing House, 1992.
2. Schey, John A., "Introduction to Manufacturing Processes", McGraw Hill, Second
Edition, 1987.
3. N.D BHATT, Engineering Drawing, 5th edition.
4. Geometric development, San foundry Aug 12,2013.
5. Roger Timings, Fabrication and welding engineering ,1st edition 2008,
6. N.D. BHATT, Engineering drawing 5th edition, 2011.
7. KENNETH MORLING, Geometric and engineering drawing 3rd edition,2010
8. Evan A. ATKINS, Practical sheet and plate metal work 1st edition,1908.
9. http://www.aust.edu/civil/lab_manual/ce_100.pdf
10. https://deseng.ryerson.ca/dokuwiki/_media/mec222:asc2.pdf
11. http://www.mhhe.com/engcs/drawgr/bertolinetgc/etext/chapt08.pdf

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Participants of this Module (Training Material) Preparation

S/ Full Name Qualifi Field of Organiz Mobile E-mail

N cation Study ation/ number
o. (Level) Instituti
on
1 Kebede Taddesse A (M Mechanic M/G/M/ 091135 kebedetad2016@gmail.
.Tech) al Buli 5094 com
Engineeri PTC
ng
2 Adisu Alemayehu A Manufact Bonga 091782 @gmail.com
(MSC) uring PTC 5397

3 Firewu Bekele A Manufact D/Berha 091082

(MSC) uring n .PTC 6193 firewbekele652@gmail.
com
4 Welela Seid A Manufact Awassa 092528 @gmail.com
(MSC) uring PTC 8242

5 Daniel Tilahun A Manufact Arbamin 091246 @gmail.com

(MSC) uring ch PTC 3438

6 Kasahun Tesfaye A Manufact Bishoftu 091324 @gmail.com

(MSC) uring PTC 4132

7 Hailu Garomsa A Manufact Woliso 091780 @gmail.com

(MSC) uring PTC 6028

Page 42 of 42 Ministry of Labor and Skill Version -1

Geometric Development
Author/Copyright October, 2023