BILKENT UNIVERSITYMECHANICAL ENGINEERING DEPARTMENT

ME 102: Introduction to Systems Engineering

Conceptual Design Process Report

Project 1

Group No: 214

Group Name: The Tatar Ramadans

Group Members: Mehmet Kelleci 21102196

Ekrem Sahin 21002038

Adil Can Murat Yldz 21002427

Submitted by: The Tatar Ramadans

Submitted to: Asst. Prof. Dr. Mujdat Tohumcu

Submission Date: 29 April 2013

Contents

Abstract 3

1 Objective 4

2 Requierements 4

3 Feasibility Analysis 4

4 Project Alternative I: 5

5 Project Alternative II: 7

6 Safety Factor Against Failure 8

7 Conclusion 8

8 Duties of Group Members During the Design Process: 9

9 Cost Document: 9

10 Material List: 10

11 Production Process: 10

12 User and Maintenance Manual: 11

13 Drawings of Design Alternative 1: 12

14 Drawings of Design Alternative 2: 15

2

Abstract

The objective of the project is to generate a practical and entertaining product that satisfies the the

restrictions of the project requirements. At the end of all the design and manufacturing processes,

the group produced a guitar from a cigarette box. The money spent on the project did not exceed

the limit of one hundred liras. Payments are shown in the tables below.

3

1 Objective

The choice of our group about the project of the course Introduction to Systems Engineering is to

create a useful, entertaining, resolvable and portable object which is made totally from the wood

and a few pieces of metals intended to use in the assembly process. As a result of the discussions

which are made within the group members, a guitar which is separable, tiny, useful, cheap, original

in design is decided to be made.

2 Requierements

As the decision of the group had made and the restrictions of the rules of the project commands,

the guitar is needed to be produced nearly totally from the wood. Its sizes should not exceed

the limits of 40 x 40 x 40 cm3. Its cost is limited 100 liras. So, as we try to find our way, we

consider all the limitations. We restrict our desires to stay within the acceptable limits of project

requirements so we decide to make our guitar tiny. In order to not exceed the volume limit we try

to make it resolvable in to pieces in a way that when the guitar is resolved in to pieces it should fit

into a box which has a volume of 64000 cm3 which is equal to 0.64 m3. With these considerations

and restrictions we evaluated our alternatives which are mentioned below separately.

3 Feasibility Analysis

The requirements, restrictions and our desires are mentioned above. According to these three

main determinative factors, we define our system system parameters are as follows: Producability

, Resolvability, Appearance and Cost. According to their importance, Producability is 30%, Re-

solvability is 30%, Appearance is 20% and Cost is 20% percentages are determined. And as our

application requires we gave importance points to these parameters. During the conceptual design

4

process, we achieved two possible design alternatives. We give points to these alternatives and

decide which alternative is more feasible and logical to applicate.

4 Project Alternative I:

In this design alternative, it is intended to build the main part of the guitar which is an empty

wooden box, by handmade. By making the body of the guitar hand, it would we possible to have

the shape whatever is desired. It is intended to have chamfered corners and a circular fillet to

achieve the most common guitar shape. The body of the guitar is designed 20 x 20 cm3 which is

not beyond the size limitations.

The handle of the guitar is designed as two parts. It is important to emphasize that, to stay

within the limitations, we make the criterion that, after resolving the guitar in to its pieces it must

fit in to a 40x40x40cm3 box. According to this criterion, the handle of the guitar is needed to be

made about two pieces. The total length of the handle is 40cm and width is 4cm.These pieces are

intended to consolidate with help of a few number of magnets which are attached to the pieces.

Likewise, the connection between the box and handle is supplied with magnets.

Of course, to achieve the sound, it is needed to tighten a number of wires. We decide to tighten

three wires, as because the volume of the guitar is restricted so the width of the handle is also

narrow. It would not be possible to have six wires. Apart from that, our purpose is not create a real

guitar but to create a portable and entertaining item.

According to the information mentioned above, it is time to give points to the alternative one

according to our pre-defined design parameters. Recall that parameters are Producability, Resolv-

ability, Appearance and Cost. It is said above that, the box of the guitar is intended to be done by

hand. If the box is made by hand, then, it is possible to have the shape whatever we want. The

desired shape is chamfered corners, circular hole at the middle of the box. According to these facts,

5

the box would have a very nice looking, but making the box by hand is not easy. We do not have the

required manufacturing items and manufacturing experience to do that. Apart from that, without

experience, we would loose to many useful parts and the cost would increase automatically. And

again, apart from that, wood is material that is easy to work with turning machine and fraise. So,

if it is done by hand, it would look good but the cost would increase dramatically. And there is a

huge lack of manufacturing experience. Points for Producability is 15 of 30 and Appearance is 20

of 20 are given.

It is said that, the parts are designed to attach with help of a number of magnets. This is actually

a very practical idea but it is again very hard to applicate. Because, to attach the handle parts and

box with help of magnets, first, magnets should be attached to the handle and box parts. It is easy

to locate magnets on boxes but it is not very easy to locate them on handle parts. Because, we have

size limitations, and need powerful magnets to hold them in one piece but attaching them to the

parts is a real issue. So, if we could have used magnets, the resolvability would be great. Point for

Resolvability is given as 30 of 30.

Evaluation of Project Alternative I: Now, there is a crucial part about tensioning the wires

on the box to the end of the handle in a way that wires will across the hole at the middle of the

box. In this design alternative, because of the usage of magnets, we do not have the luxury to

exert force in the direction perpendicular to the ground on the parts. We need only compressive

forces, because we cant rely on too much on magnets. So, in this design alternative, the wires are

tensioned between the box and the handle with the help of nails. three nails on. And as a general

evaluation for cos is made and for Cost parameter the point is determined as 5 out of 20. Total

point for this alternative is 70.

6

5 Project Alternative II:

In this alternative, our group think of having the box readily produced. Because having a fabricated

box and then going on to design according to this box is much more easy than manufacturing the

box by hand. With this movement, the manufacturability is increased by a huge amount. By the

past experiences that we faced, it is obvious that choosing the parts that would be produced easily

and making the design based on easily produced parts is a very practical way to have an item which

is ready for serial manufacturing. Of course, our duty is not enable the project to be manufactured

my huge amounts, but is an obvious fact that, if we make our design as if we produce thousands

of guitars, even if we dont, we can obtain our project more easily. So with this thought, the group

used an already produced box.

Apart from its, producability, its appearance changes according to the box we obtained. The

box we obtain is an old cigarette box which has stickers on it and sharp corners. these unwanted

details reduces the attractiveness of the appearance by huge amount. But of course, in the criterion

mentioned above, to manufacture easily is more important than to have a good looking object. So

our point for appearance is 10 out of 20 and for producability is 30 out of 25.

In this design alternative, our group brought a different point of view to the resolvability of

the project. According to this alternative, there are two main parts, box and handle. Box is an old

cigarette box and handle consists of two parts. These two parts of handle are attached with the help

of two wooden nails. First, in the machine shop, we make two circular openings on the handle

which are seeing each other. And then with an appropriate piece of wood which has a cylindrical

shape, they are attached. To satisfy the resolvability criterion, this is actually a great way because

we locate the cylindrical wooden nails in a way that a little length of it can be held by hand so that

when the owner of the guitar desired, he / she can take off the wooden nails and then resolve guitar

in to pieces.

Evaluation of Project Alternative II: To evaluate the second design overall, because of having

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Table 1: Grading Procedure of Design AlternativesProducability Resolvability Appearance Cost Overall

Design Alternatives 30 % 30 % 20 % 20 % 100

Alternative I 15 30 20 5 70 points

Alternative II 30 25 5 20 80 points

the box readily, and as mentioned above, our box is an old cigarette box which has no cost to us,

the crtierion cost is satisfied very appropriately. The criterion resolvability also satisfied very well

so our point for the cost criterion is 20 out of 20 and for the resolvability is 30 out of 25. Total

point for this design alternative is 80 points.

6 Safety Factor Against Failure

According to the calculation that the group make, while a person plays guitar he/she applies a

force approximately 10 Newtons. The smallest cross-sectional are that the guitar have is 32 104

m2. So allowable stress on the critical cross-sectional area is allowable = NA =10

32104 = 3125 Pa.

The force that may break the guitar during usage is determined as 100 N. So the stress for failure

f ailure = 3125 104. Factor of safety against failure is X f = fallowable = 10.

7 Conclusion

Two design alternatives are explained. The criterions that commands our restrictions and limi-

tations are predefined before starting to the project. our grade policy and reasons about giving

points to our design alternatives are explained above. According to the predefined criterions, best

choice is the second design alternative. Because second alternative is more effective in obeying the

criterions. ( For given points according to the criterions see Table 1.)

8

8 Duties of Group Members During the Design Process:

Ekrem Sahin: To increase the resolvability criterion, he proposed to use wooden nails. The idea

is simply is as follows. The purpose is to have the handle part in to two distinct part. He says

that with the help of the tool fraise, having two holes on the handle part and attaching the nails.

A detailed explanation is given above. He provided very easinesses during the obtaining the parts

those will be used in project.

Mehmet Kelleci: He is the CAD user of the group. The drawings are made by his hand.

During the manufacturing process, he proposed clever ways to have the project in a more practical

manner( having elliptical hole on the box, attachment of box to the handle part, etc...) The docu-

mentation of the conceptual design process is also a great percentage of his work.

Adil Can Murat Yldz: The idea of making a guitar box is his idea. When the group is stuck

with manufacturing the box by hand, he proposed to have the box readily. As he interested in

guitars himself, he proposed clever ways to tension the wires on the guitar.

9 Cost Document:

As the project restrictions ordered to our group, our main purpose is to do not exceed the cost

limit of 100 TL. Used components and their costs are documented below. Again, it is important

emphasize that, our main purpose is to find the cheapest components of all.

Cigarette Box: It is the main part of the guitar. It is cost free, because it was present in our

possession.

Handle Part: 9TL

Wood Glue: 5TL

9

Guitar Wires:10TL

Holdfest: 5TL

Manufacturing Costs: All the labors are belong to the group members. There is no cost for

this.

Total Cost: 29TL

10 Material List:

Cigarette Box: Made by wooden.

Handle Part: Made by wooden.

Guitar Wires: Made by copper.

Holdfest: Made by plastic.

11 Production Process:

The main purpose of the design as mentioned above, is to have a product which has practical spec-

ifications of portability. All our labors are in the purpose of achieving this fact. The manufacturing

process is take place in the machine shop of our department by three members of our group. First

it is needed to assemble the handle part to the cigarette box to get the ideal looking of a real guitar.

To assemble that, we cut the box in a shape that the end of the handle part would just fit it. It is

important not to have any cracks or wholes in the box in order to have a healthy sound from the

guitar.

Second main purpose is to have the handle part in two distinct parts to achieve the portability.

To get this fact, handle part is divided in to pieces in a way that, one of the piece will have a

protrusion likewise other part of handle too. These two parts are drilled at four places to insert the

wooden protrusions.

10

Other objectives was to tension the wires over the guitar and hold them with wires. This was

easy. Three screws are used for three wires and tensioning process is done.

12 User and Maintenance Manual:

As mentioned above, the cigarette box and one piece of the handle part are sticked together. To use

the guitar, first, second handle part should be assembled by wooden sticks. Wooden sticks must be

inserted to the wholes. As mentioned above, our design is highly portable, so only thing to do after

assemblying the second part of the handle is to tension the wires to the screws. And then enjoy

your cigarette box guitar.

In a possible maintenance issue, if the problem is at the body part of the guitar, there is nothing

to do, guitar is off from the usage. But, if the problem is at another place, there are ways to fix it. If

one of the wires are broken, wire could be replaced. There is no possibility about having a problem

with screws unless user crashes the guitar to the ground. If the second handle part is broken than

user may change it too. There are auxiliary parts are present.

11

13 Drawings of Design Alternative 1:

12

50

200

20

12

16,33

Tatar Ramadans

Wooden

The Main Part of The Guitar

AIRLI:

A4

SAYFA / LEK:

RESM NO.

BALIK:

REVZYONTEKNK RESM LEKLENDRME

MALZEME:

TARHMZASM

KESKN KENARLARIPAHLAYIN VEKIRIN

BTRME:AKS BELRTLMED SRECE:BOYUTLAR MLMETREDRYZEY CLASI:TOLERANSLAR: DORUSAL: AISAL:

KALTE

RET.

ONAY.

DENET.

ZEN

2X R2,50

5

50

12

IV.

Wire Holder

WoodenAIRLI:

A4

SAYFA / LEK:

RESM NO.

BALIK:

REVZYONTEKNK RESM LEKLENDRME

MALZEME:

TARHMZASM

KESKN KENARLARIPAHLAYIN VEKIRIN

BTRME:AKS BELRTLMED SRECE:BOYUTLAR MLMETREDRYZEY CLASI:TOLERANSLAR: DORUSAL: AISAL:

KALTE

RET.

ONAY.

DENET.

ZEN

13

20

12

163,2

9

Holding Part

IIIWooden

AIRLI:

A4

SAYFA / LEK:

RESM NO.

BALIK:

REVZYONTEKNK RESM LEKLENDRME

MALZEME:

TARHMZASM

KESKN KENARLARIPAHLAYIN VEKIRIN

BTRME:AKS BELRTLMED SRECE:BOYUTLAR MLMETREDRYZEY CLASI:TOLERANSLAR: DORUSAL: AISAL:

KALTE

RET.

ONAY.

DENET.

ZEN

4

20

12

Magnet II

The Holder Part, made by magnet

AIRLI:

A4

SAYFA / LEK:

RESM NO.

BALIK:

REVZYONTEKNK RESM LEKLENDRME

MALZEME:

TARHMZASM

KESKN KENARLARIPAHLAYIN VEKIRIN

BTRME:AKS BELRTLMED SRECE:BOYUTLAR MLMETREDRYZEY CLASI:TOLERANSLAR: DORUSAL: AISAL:

KALTE

RET.

ONAY.

DENET.

ZEN

14

14 Drawings of Design Alternative 2:

200

16,

33

TRUE R4

77,45

24,49

8,1

7

85,84

30

15

190

28

190

120

120

16

25

6

100

10

3 25

25

17

18