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
7
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
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