DESIGN, FABRICATION AND TESTING OF A PEDAL – POWERED HACKSAW
MACHINE AS ALTERNATIVE TO POWER HACKSAW MACHINE
In Partial Fulfilment of the
Requirement for the Degree in
Bachelor of Science in Mechanical Engineering
By:
Etis, Josh Mari G.
Lahaylahay, Emmanuel L.
Postrero, Joshua P.
Engr. Khareljoy S. Sungcad, MME
Co-Adviser
Engr. Jose Arvin S. Tordillo, MME
Thesis Adviser
October 05, 2021
i
University of San Carlos – Technological Center
Nasipit, Talamban, Cebu City
School of Engineering
Department of Mechanical and Manufacturing Engineering
APPROVAL SHEET
Name of Participants:
Etis,
Josh Mari
G.
Lahaylahay,
Emmanuel
L.
Postrero,
Joshua
P.
Major
: Bachelor of Science in Mechanical Engineering
Project Title
: “ Design, Fabrication and Testing of a Pedal – Powered Hacksaw Machine as
Alternative to Power Hacksaw Machine”
Final Defense Date : October 05, 2021
PROJECT EXAMINATION COMMITTEE
Engr. Armando A. Siez, MME
Dr. Virgilio Y. Abellana, PhD.
Committee Member
Committee Member
Engr. Earl Ray G. Aninon, MME
Committee Chair
Engr. Khareljoy S. Sungcad, MME
Co-Adviser
Engr. Jose Arvin S. Tordillo, MME
Adviser
i
ACKNOWLEDGEMENT
Without the help of the people behind us, this paper will not be possible. First of all, we would
like to thank the almighty God for giving us the courage, knowledge and wisdom to pursue this
thesis. Also, to our mentors Engr. Khareljoy S. Sungcad and Engr. Jose Arvin S. Tordillo, for guiding
us during the process of our study. We would also like to thank our panelists, Engr. Earl Ray G.
Aniñon, Engr. Armando A. Siez, Engr. Gabriel Dominic R. Baygan and Dr. Virgilio Y. Abellana
for clarifying our study with important details to be done in our paper. Moreover, this study will not
be possible without the tools and instruments from the University of San Carlos.
Special thanks to Padeeena Enterprises for providing us the materials needed for
fabrication and to the USC-TC Machine Shop Assistant Elmo Amaro also known as “Kuya Toto”
for assisting us during the fabrication and who let us worked our experiment in University of San
Carlos Machine Shop.
We would like also to thank our parents, siblings, and relatives for their love, support,
guidance, encouragement, assistance, and patience which helped us in completing this thesis. Also, to
our classmates who gave us insights and ideas in making this thesis and for boosting our morale in
times of difficulty. This study is for the glory of God.
ii
ABSTRACT
Pedal powered hacksaw machine is a cutting machine can cut any material depending on the
specifications of the hacksaw blade used at table 2.1 and transmitted by the used of the pedal. This machine
has been designed and fabricated for cutting of different workpiece which are the solid mildsteel shaft,
engineering plastic, and wood lumber at different cutting angles. The pedal powered hacksaw machine
design consists of 15 parts which are the 2 chain drives, 4 sprockets, shafts, flywheel, block bearing,
connecting rods, machine frame, and hacksaw blade. This machine has been tested with different cutting
workpiece by comparing the data gathered by electric power hacksaw which were the solid mild steel
shaft, engineering plastic, and wood lumber.
This study design, fabricate and test of pedal powered hacksaw machine that can be used with or
without electricity. The parameters had been gathered during the experiment are the cutting time, cutting
speed, depth of cut, power input, power output, and the efficiency at different cutting angle. With the use of
three sample workpieces, the pedal powered hacksaw machine was tested with its cutting time of 180
seconds using a mild steel shaft, 10.704 seconds for engineering plastic and 28.32 seconds for the wooden
lumber compared to the electric powered hacksaw which is tested with its cutting time of 117.2 seconds
using a mild steel shaft, 6.08 seconds for engineering plastic and 8.19 seconds for the wooden lumber.
The cutting performance of the pedal powered hacksaw was determined at 0.06 mm/s for the mild steel
workpiece, 2.37 mm/s for the engineering plastic and 1.448 mm/s for the wooden lumber in comparison
to the cutting performance of the electric powered hacksaw that was determined at 0.2167 mm/s for the
mild steel workpiece, 4.178 mm/s for the engineering plastic and 5 mm/s for the wooden lumber
workpiece. The pedal powered hacksaw machine can be operated without the access of electricity with less
operating cost.
iii
DEFINITION OF TERMS
Cutting Force
Is a force that is generated by the cutting tool as it machines the
workpiece.
Pedal
Each of a pair of foot-operated levers used for powering a bicycle or other
vehicle propelled by the legs.
Chain Drive
A way of transmitting mechanical power from one place to another.
Hacksaw Blade
A saw with a narrow fine-toothed blade set in a frame, used especially for
cutting metal.
Hacksaw Frame
It is consists of head, handle, and backbone which compensate different
stresses that occur in the hacksaw blade due to the force when cutting.
Sprocket
It is a profiled wheel with teeth, or cogs, that mesh with a chain, track or
other perforated or indented material.
Shaft
A rotating machine element, usually circular in cross section, which is
used to transmit power from one part to another, or from a machine which
produces power to a machine which absorbs power.
iv
Flywheel
A mechanical device specifically designed to use the conservation of
angular momentum so as to efficiently store rotational energy; a form of
kinetic energy proportional to the product of its moment of inertia and the
square of its rotational speed.
Slider-Crank Linkages
Four-link mechanism with three revolute joints and one prismatic, or
sliding joint.
Velocity Ratio
The ratio of a distance through which any part of a machine moves to that
which the driving part moves during the same time.
Force
Strength or energy exerted or brought to bear ;cause of motion or change ;
active power.
Slider-Crank Mechanism
It is an arrangement of mechanical parts designed to convert straight-line
motion to rotary motion, as in a reciprocating piston engine, or to convert
rotary motion to straight-line motion, as in a reciprocating the hacksaw
frame.
v
NOMENCLATURE
Notations
F
Force of the object, N
m
Mass of the object, kg
a
Gravitational acceleration, m/s2
ΣF
Summation of forces acting, N
ΣM
Moment of Inertia acting, N-m
σ
Stress, N/m2
A
Cross-sectional Area of the plane, m2
θ
Angle direction of the forces
Fx
Horizontal Forces, N
Fy
Vertical Forces, N
p
Pitch of chain
D
Diameter of pitch circle, mm
T
Teeth of the sprocket
re
Flank radius of the sprocket, mm
d1
Roller diameter, mm
r1
Roller seating radius, mm
α
Roller seating angle
vi
ha
Tooth height above of the pitch polygon, mm
Da
Top Diameter of the sprocket, mm
bf1
Tooth width of the sprocket, mm
b1
Width between inner plates, mm
p1
Transverse pitch
N
Speed of the sprocket, rpm
x
Center distance of the chain drive, mm
L
Length of the chain, mm
K
Product of the number chain links
V
Average pitch line velocity, m/s
Ks
Service factor of the chain
K1
Load factor of the chain
K2
Lubrication factor of the chain
K3
Rating factor of the chain
Pdesign
Design power, kW
Ptransmitted
Power transmitted, W
W
Load transmitted by the chain drive, N
FT
Tangential driving force, N
vii
WB
Breaking strength of the chain, N
FS
Factor of Safety
T
Torque, Nm
τ
Shear stress, N/m2
ds
Shaft diameter, mm
M
Bending moment of the shaft, mm
I
Moment of cross-sectional area, mm2
y
Length of the shaft, mm
Wf
Weight of flywheel, N
mf
Mass of flywheel, kg
R
Radius of the flywheel rim, mm
t
Thickness of the flywheel, mm
ρ
Density of material, kg/m3
VR
Velocity Ratio
Rflywheel
Radius of the flywheel, mm
IMA
Ideal Mechanical Advantage
r
Radius of the crank, mm
ω
Angular velocity, rad/s
viii
VB/A
Magnitude of the velocity, m/s
b
Width, mm
h
Depth, mm
Ixx
Moment of Inertia of a rectangular connecting rod in x-axis, N-mm
Iyy
Moment of Inertia of a rectangular connecting rod in y-axis, N-mm
Wcr
Buckling load, N
Wc
Crushing load of the material, N
σc
Product of the crushing stress, N/m2
E
Modulus of Elasticity, GPA
a
Rankine’s Constant
k
Radius of gyration, mm
σb
Bending stress, N/mm2
s
Size of the weld, mm
dp
Diameter of the pin, m
NO
Output Speed, spm
ix
TABLE OF CONTENTS
APPROVAL SHEET ..................................................................................................................................... i
ACKNOWLEDGEMENT ............................................................................................................................ ii
ABSTRACT................................................................................................................................................. iii
DEFINITION OF TERMS .......................................................................................................................... iv
NOMENCLATURE .................................................................................................................................... vi
LIST OF FIGURES ...................................................................................................................................... 1
LIST OF TABLES ........................................................................................................................................ 3
CHAPTER 1: THE PROBLEM AND ITS SCOPE ...................................................................................... 4
Introduction ............................................................................................................................................... 4
Statement of the Problem .......................................................................................................................... 5
Objectives ................................................................................................................................................. 6
Significance of the Study .......................................................................................................................... 6
Scope and Limitations............................................................................................................................... 7
CHAPTER 2. REVIEW OF RELATED LITERATURE ............................................................................. 9
2.1 Pedal Power ........................................................................................................................................ 9
2.2 Hacksaw Blades ................................................................................................................................ 10
2.3 Hacksaw Machine ............................................................................................................................. 11
2.3.1 Power Hacksaw Machine ............................................................................................................... 12
2.3.2 Pedal Operated Hacksaw Machine ............................................................................................ 12
2.4 Operating Cost .............................................................................................................................. 13
2.5 Parameters that affect the performance of Hacksaw Machine .......................................................... 13
2.5.1 Cutting Speed ............................................................................................................................. 14
2.5.2 Cutting Time .............................................................................................................................. 14
2.5.3 Depth of Cut ............................................................................................................................... 15
2.6 Potential Contribution of the Proposed study to the Existing Body of Knowledge .......................... 18
CHAPTER 3. THEORETICAL BACKGROUND ..................................................................................... 20
3.1 Pedal Powered Hacksaw ................................................................................................................... 20
3.2 Force ..................................................................................................................................................... 20
3.3 Chain Drive ....................................................................................................................................... 22
3.3.1 Bush Roller Chain ...................................................................................................................... 23
3.3.2 Transmitted Power ..................................................................................................................... 24
3.3.3 Pedalling Speed .......................................................................................................................... 24
x
3.3.4 Pitch ........................................................................................................................................... 25
3.3.5 Pitch Diameter ........................................................................................................................... 25
3.3.6 Sprocket Tooth ........................................................................................................................... 27
3.3.7 Characteristics of Roller Chain .................................................................................................. 28
3.3.8 Velocity Ratio (Sprockets) ......................................................................................................... 29
3.3.9 Center Distance .......................................................................................................................... 30
3.3.10 Length of Chain ....................................................................................................................... 31
3.3.11 Pitch Line Velocity .................................................................................................................. 31
3.3.12 Service factor ........................................................................................................................... 32
3.3.13 Design Power ........................................................................................................................... 33
3.3.14 Load of Chain .......................................................................................................................... 33
3.3.15 Factor of Safety ........................................................................................................................ 34
3.4 Shaft .................................................................................................................................................. 34
3.5 Flange Coupling ................................................................................................................................ 35
3.6 Flywheel............................................................................................................................................ 37
3.6.1 Velocity Ratio (Flywheel) .......................................................................................................... 38
3.7 Mechanical Advantage...................................................................................................................... 38
3.7.1 Ideal Mechanical Advantage ...................................................................................................... 39
3.8 Slider Crank Mechanism................................................................................................................... 39
3.9 Connecting Rod ................................................................................................................................ 41
3.10 Hacksaw .......................................................................................................................................... 44
3.10.1 Hacksaw Frame ........................................................................................................................ 45
3.10.2 Hacksaw Blade......................................................................................................................... 46
3.10.3 Theory on Metal Cutting .......................................................................................................... 48
3.10.4 Number of Strokes ................................................................................................................... 49
3.10.5 Cutting Time ............................................................................................................................ 49
3.10.6 Net Power................................................................................................................................. 50
3.11 Efficiency ........................................................................................................................................ 50
3.11.1 Mechanical Efficiency ............................................................................................................. 50
3.11.2 Overall Efficiency .................................................................................................................... 51
CHAPTER IV: METHODOLOGY ............................................................................................................ 52
4.1 Flow of the Study .............................................................................................................................. 52
4.2 Design Conceptualization ................................................................................................................. 53
xi
4.2.1 Designing the Pedal Operated Hacksaw Machine ..................................................................... 53
4.2.2 Design Calculation of Sprockets ................................................................................................ 56
4.2.3 Design Calculation of Chain Drives .......................................................................................... 59
4.2.4 Design Calculation of Shafts...................................................................................................... 60
4.2.5 Design Calculation of Flywheel ................................................................................................. 61
4.2.6 Design Calculation of Connecting Rod...................................................................................... 62
4.2.7 Design Calculation of Crank Pin ............................................................................................... 63
4.2.8 Design Calculation of Hacksaw ................................................................................................. 64
4.3 Fabrication ........................................................................................................................................ 64
4.4 Testing and Data Gathering .............................................................................................................. 68
4.4.1 Experimental Set-up ................................................................................................................... 68
4.4.2 Testing Instruments and Equipment .......................................................................................... 70
4.4.3 Testing Procedure ...................................................................................................................... 71
4.4.4 Fabricating Machines and Equipment ........................................................................................ 73
CHAPTER V: RESULTS AND DISCUSSION ......................................................................................... 77
CHAPTER VI: CONCLUSION AND RECOMMENDATION ................................................................ 80
6.1 Conclusion ........................................................................................................................................ 80
6.2 Recommendation .............................................................................................................................. 80
Bill of materials....................................................................................................................................... 81
Gantt chart............................................................................................................................................... 84
REFERENCES ........................................................................................................................................... 85
APPENDIX A: PEDAL POWERED HACKSAW MACHINE EXPERIMENTAL DATA ..................... 90
APPENDIX B: ELECTRIC POWERED HACKSAW EXPERIMENTAL DATA ................................... 91
APPENDIX C: USERS’S MANUAL GUIDE FOR PEDAL-POWERED HACKSAW MACHINE
OPERATION .............................................................................................................................................. 93
APPENDIX D: PEDAL OPERATED HACKSAW CALCULATIONS ................................................... 98
Sprocket Design Calculations ................................................................................................................. 98
Chain Drives Design Calculations ........................................................................................................ 106
Shaft Design Calculations ..................................................................................................................... 108
Flywheel Design Calculations .............................................................................................................. 113
Crank Pin Design Calculations ............................................................................................................. 115
Connecting Rod Calculations ............................................................................................................... 116
Bicycle Frame Design Calculations ...................................................................................................... 121
xii
Hacksaw Calculations ........................................................................................................................... 124
Efficiency Calculations ......................................................................................................................... 128
xiii
LIST OF FIGURES
Figure 2.1 The Optimum Pedalling Rate over the Desired Power Output ………………………………..….8
Figure 2.2 Piling - up Action Found when Sawing a Copper Workpiece…………………………………....15
Figure 2.3 Discontinuous Piling - up Action Observed when Sawing an Aluminum Workpiece………….16
Figure 2.4 Combined Discontinuous and Piling - up action observed when sawing a lead workpiece….17
Figure 3.1 The vector nature of a force…………………………………………………………………………...20
Figure 3.2 Chain Drive……………………………………………………………………………………….……..21
Figure 3.3 Terms used in chain drive………………………………………………………….…………………..22
Figure 3.4 Bush Roller Chain……………………………………………………………………….……………...23
Figure 3.5 The optimum pedalling rate over the desired power output………………….…………………...24
Figure 3.6 Tooth Profile of the Sprocket………………………………………………………….…………..…..25
Figure 3.7 Rim Profile of the Sprocket…………………………………………………………………………….26
Figure 3.8 Center Distance of the Chain Drive……………………………………………….….….…………..29
Figure 3.9 Flange coupling………………………………………….……………….……………….…………….34
Figure 3.10 The Flywheel…………………………………………………………….…..…………………………36
Figure 3.11 Free body diagram of a simple lever…………………………………………………….…………37
Figure 3.12 Slider Crank Mechanism of the Pedal Powered Hacksaw………………………………………38
Figure 3.13 Graphical representation of eqn 3.35………………………………………………………………39
Figure 3.14 Moment of inertia of a (a) rectangular cross-section and a (b) circular cross-section……..40
Figure 3.15 Buckling of connecting rod…………………………………………………………………………..41
Figure 3.16 Parts of the Hacksaw…………………………………………………………………………………41
Figure 3.17 Parts of the Hacksaw Blade……………………………………………………………………...….45
Figure 3.18 The system of forces acting by the cutting tool during the cutting process……………………47
Figure 4.1 Flow of the Study……………………………………………………………………………………….50
Figure 4.2 Pedal Operated Hacksaw Machine Isometric View……………………………………………….51
1
Figure 4.3 Pedal Operated Hacksaw Machine Exploded View……………………………………….….……52
Figure 4.4 Sprockets…………………………………………………………………………………………..….….55
Figure 4.5 Image During Fabrication………………………………………………………...……………...…...63
Figure 4.6 Image During Fabrication …………………………………………………..………………….…….63
Figure 4.7 Image During Fabrication …………………………………………...………………..……….…….64
Figure 4.8 Image During Fabrication ……………………………………….…..………………..………….….64
Figure 4.9 Image During Fabrication ……………………………………….…..…………….………….……..65
Figure 4.10 Image During Fabrication …………………………………………..……………….……………..65
Figure 4.11 Image During Fabrication ……………………………………………………….………………...66
Figure 4.12 Experimental Set-up………………………………….……………………..……………………….67
Figure 4.13 Power Hacksaw Machine Set-up…………..………………………………………………………67
Figure 5 Gantt Chart…………………………………..…..………………………………………………………82
2
LIST OF TABLES
Table 2.1 Standard TPI of the hacksaw blade………………………………………………………………….…..9
Table 3.1 Number of teeth on the smaller sprocket…………………………………………….………………...27
Table 3.2 Characteristics of roller chains according to IS: 2403 — 1991………………….………………..28
Table 3.3 Power rating of a simple roller chain in rpm……………………………………….………………..29
Table 3.4 Load factor of chain drives………………………………………………………….………………….31
Table 3.5 Lubrication factor of chain drives………………………………………………….……………….…31
Table 3.6 Rating factor of chain drives………………………………………………………….………………..32
Table 3.7 Permissible crushing stress and rankine’s constant for various materials……….……………..42
Table 3.8 Recommended minimum size of welds……………………………………….……………………….43
Table 3.9 Standard Dimensions for Machine Hacksaw Blades……………………….………………………46
Table 4.1 Exploded View Parts……………………………………………………………….……….…………..52
Table 4.2 Dimensions of 4 Sprockets…………………………………………………….……………….………56
Table 4.3 Chain Drive Dimensions……………………………………………………….………………..……..58
Table 4.4 Connecting Rods Dimensions………………………………………………….…………….….…….61
Table 4.5 Instruments and Equipment needed for the experiment………………….……………….…….….68
Table 4.6 Machines and Equipment for Fabrication…………………………………………….………..…...71
Table 5 Bill of Materials……………………………………………………………………….…………..………79
3
CHAPTER 1: THE PROBLEM AND ITS SCOPE
Introduction
Industrial workers nowadays used high powered cutting machines in order to cut the material. The
most common cutting machine to cut light material is the power hacksaw machine. Since the beginning,
muscle power was commonly utilized by the use of hands, arms and back as means of providing energy
towards an operating machine. With the right involvement of which muscle is applied to operate on a
machine during a certain task, the transfer of mechanical power can be optimized, making work done
without effort [11]. A bicycle is one of the examples of a device that utilizes the use of the muscle power in
an efficient manner which uses the legs as one of the sufficient providers of human power [19]. This
concept led to the development of bicycles which still lie on the primary utilization of pedal force at a
power rate of 75 watts or more nowadays. In the lower-power extent there are various employments of
pedal force for agribusiness, development, water siphoning, and electrical age that appear to be possibly
beneficial, in any event when electrical or inner burning motor force is inaccessible or over-the-top
expensive[1].
This technology is the transfer of energy from a human source using a foot pedal and crank system.
This innovation is most regularly utilized for transportation and has been utilized to drive bikes for over a
hundred years. Less regularly pedal are utilized to control agricultural and hand devices and even to
produce electricity. A few applications incorporate pedal controlled laptops, pedal powered grinders, and
pedal powered water wells. Some third world improvement extends right now change utilized bikes into
pedal powered tools for manageable advancement[5].
Hacksaws have played a major role in almost every part of material in terms of cutting such as flat
plates, rods, and such other things that are required for auto repairing shops, general fixing shops, fitting
shops, welding shops, and specialized organizations. With its fine-toothed saw blade attached to a cshaped frame, the hacksaw is capable of cutting metals that are mainly used in the industrial sector. A
hand-held hacksaw is provided with a handle and metal casing as support when cutting the workpiece by
hand, followed by removable pins that are used to hold the blade together under strain[6]. Manual
4
operation for hand-held hacksaws is tiring and inconvenient due to the amount of cutting depth by the
limited amount of force applied during cutting. The fact that solid shafts with diameter thickness of 20
mm and above are unachievable by hand-held cutting, which is concurred by technicians and craftsmen[9].
For industries to accomplish large scale manufacturing, it is important to cut metal bars at high rates.
The hacksaw machine reduces the time and effort of the user during cutting operation, which are
commonly powered by an electric motor. Electrically powered hacksaw machines are only accessible in
the market for utilization in the shop floor today since other hacksaw machines are being developed for
improvement[7]. Limited access to electricity is one of the main disadvantages for motor- powered
hacksaws along with its cost where maintenance is to be shouldered including utility bills which defeats
the purpose of convenience. Studies have proven that the outcome of pedal-operated hacksaws require
less maintenance in order to operate while human effort is reduced without access to electricity[8].
Although pedal-operated hacksaws are still in development, the outcome continues to improve today as
more innovations in the design continue to flourish in the future. In this study, the pedal-operated
hacksaw is designed to be more efficient in terms of productivity and convenience along with its
improved efficiency. Some features of the pedal powered hacksaw applied on the flywheel, the angle
cutting system for the hacksaw and wheels that ensures portability of the hacksaw machine and
convenience to the user.
Statement of the Problem:
Power hacksaw machines utilize electricity in order to operate in auto repairing shops, general
fixing shops, fitting shops, welding shops, and specialized organizations or large industrial shops,
increasing the utility cost for cutting. Alternative methods have been investigated by researchers that
reduce the operation cost for cutting. Pedal power is the most efficient alternative method suitable for
indoor operations without access to electricity, reducing the utility cost. Performance studies related to
pedal operated hacksaw machines were compared based on the performance of manual hacksaws, while
comparisons between its performance versus electric hacksaw machines are still being determined.
5
Hence, the research will focus on creating a pedal operated power hacksaw which is capable of
reducing its utility cost with minimal human effort and can be used in working areas like the Machine
Shop. This study will determine the performance between the pedal powered hacksaw and the electric
powered hacksaw based on the cutting time and cutting depth. Since the study of pedal operated hacksaw
machine was not yet performed at the University of San Carlos, this study of pedal operated hacksaw
machine has been proposed in order to determine the cutting performance.
Objectives
The objectives of the study are the following:
1. To design a pedal operated hacksaw machine that can operate in the same workshop place
whether electricity is available or not.
2. To fabricate a pedal driven hacksaw machine that can cut solid shaft mildsteel, engineering
plastic,and wood lumber at a maximum thickness of 70 mm.
3. To conduct performance tests of the pedal-operated hacksaw in terms of its cutting speed,
cuttingtime, and depth of cut at different cutting type material workpiece.
4. To compare productivity of the electric powered hacksaw and the pedal powered hacksaw
machine based on the data provided.
Significance of the Study
The study to be conducted will be of benefit of the following:
●
University: This study can be used by the teachers as a tool to fully teach more about Machine
Design. This study can be used as a medium in order to fully understand the theories of Machine
Design.
6
●
Students: This study can be used as a reference to improve the knowledge of the students in
building up designs of pedal operated machines.
●
Manufacturing Companies: This study can be used as an alternative tool among the production
companies that involves the process of cutting whenever electricity is not available and also to
less human effort.
●
Workers: This study can improve not only the production of output but also the physical aspects
of the user.
●
Future Researchers: This study can be used as a key reference by the future researchers for the
development of newly pedal operated machines.
●
Environment: By learning and deep understanding of power generated machines, pedal operated
machines will conserve electricity which reduces power consumption.
Scope and Limitations:
The scope and limitations of this study are the following:
●
The study will only focus on pedal powered hacksaw machine.
●
The experimental setup will be at the University of San Carlos-Technological Center
Machine Shop.
●
The maximum thickness of a material of the workpiece is limited only to 70mm.
●
The workpiece to be cut in the machine are limited only in wood lumber, engineering
plastic, and solid mild steel.
●
Friction losses during testing are neglected.
●
The materials used in the fabrication process are intended for experimentation purposes
only
●
The materials used in the fabrication are limited to mild steel for the frame and cast iron
for flywheel fabrication. The chain to be used is limited to a bicycle chain.
7
●
The data for cutting time, cutting speed, and depth of cut, at different cutting material
workpiece will be compared to the data tested in electric power hacksaw at University of
San Carlos Machine Shop.
8
CHAPTER 2. REVIEW OF RELATED LITERATURE
2.1 Pedal Power
Wilson (1986) established that the human pedal power can produce multiple times more force
which is ¼ hp by accelerating than by hand-cranking. Continuous pedaling can be served for just brief
periods at the rate of ¼ hp in approximately 10 minutes. Accelerating at a large portion of this power
which is ⅛ hp in any case can be continued for nearly an hour yet power capacity can rely on age[11]. This
technology is the transfer of energy from a human source using a foot pedal and crank system. This
innovation is most regularly utilized for transportation and has been utilized to drive bikes for over a
hundred years. The Pedaling Speed is the rate at which the user cranks the pedal [5]. Wilson (1986)
established a curve showing the optimal pedaling speed of the generated pedal power based on his study
on Pedal Power. Refer to the curve shown in figure 2.1 below, a power rate of 186.5 W or ¼ hp is marked
on the vertical side of the curve which is assumed to be the Power Output. By tracing a vertical line from
the intersection point between the Power Output and the optimal curve, the pedaling rate is determined at
70 rpm[11].
9
Figure 2.1 The Optimum Pedalling Rate over the Desired Power Output
2.2 Hacksaw Blades
Professor Nitinchandra R.Patel et al (2013) stated that the appropriate saw blade must be selected
for better operation and fine cutting by selecting a number of teeth per inch[30].There are four types of
blades based on material namely High Carbon steel, Alloy Steel, Bi-metallic strip and High-speed steel
blades. Out of these four the best suitable for cutting hard materials like a Mild steel bar and Aluminum is
a Bi-metallic blade on the basis of properties of materials, wear resistance and Cutting performance [52].
The hacksaw is a cutting tool originally used to cut metals by reciprocating motion[17]. Hacksaws continue
to improve since 1884 where George N. Clemson of the company Clemson Bros. Inc. experimented
various kinds of hacksaws of different dimensions, set of teeth and the heat treatment of the hacksaw
blades till it was proven that the hacksaw can cut 387 pieces of 1x1 inch iron [18]. Blades nowadays are
described by its TPI or the number of teeth per inch starting from the coarse blade, 14 TPI, to a very fine
blade, 32 TPI[58].
TEETH PER INCH (25MM)
SUITABLE FOR CUTTING
14 TPI
LARGE SIZES, ALUMINUM AND OTHER SOFT
METALS
18 TPI
SUITABLE FOR GENERAL WORKSHOP
CUTTING
24 TPI
FOR CUTTING STEEL PLATE UP TO 5/6MM
32 TPI
FOR CUTTING HOLLOW SECTIONS AND
10
TUBING
Table 2.1 Standard TPI of the hacksaw blade
Hacksaw blades are available in standardized lengths, and with anywhere from 3 to 32 teeth per inch
(TPI). It was based on the thickness of the material being cut, with a minimum of three teeth in the
material. Hacksaw blades are normally quite brittle, so care needs to be taken to prevent brittle fracture of
the blade. It is used as a Bi-metal blade to minimize this risk[29]. Most of the power hacksaw blades are
made from high-speed steel. Some blades have hardened high-speed steel teeth which are welded to a
tough steel back. The number of teeth per inch is dependent on the size of the hacksaw blade teeth; fewer
teeth per inch will result in a larger tooth. To be used the number of teeth per inch depends upon the
hardness of the material being cut and upon the size and shape of the workpiece. The power hacksaw
blade to be used in cutting mild materials in large sections should have 4 to 6 teeth per inch, while harder
materials in large[30].
For the maximum efficiency for the cutting process, 30 degrees inclined to the work piece of the
hacksaw blade was fixed. Heat was generated which is not desirable due to relative motion because it
leads to more wear of blade teeth as well as will change the properties of the final product. Therefore,
cutting fluids popularly known as coolant are applied while the cutting process. Different coolants are
used as per the material to be cut. There are four types of steel blades used for cutting; high carbon steel,
low alloy steel, bi-metallic steel, and high speed steel[30].
2.3 Hacksaw Machine
According to Routledge (1996), Herbert had discovered in 1990 the performance of a hacksaw machine
that can cut every much quicker when only a few teeth are in operation. It was then patented in 1902 that
machine which utilized this concept by automatically changing the angle of incidence of the blade as
cutting proceeded. These saws were commercially successful[44]. Herbert and Fletcher (1912) began to
11
developed improved methods of applying the fast cutting saw concept. A tool testing machine, working
like a lathe, was introduced when high-speed steel had just come into general use[18].
2.3.1 Power Hacksaw Machine
Most of the power hacksaws used electric motors that power a blade by using a pulley system.
Cutting speed of power hacksaws depend on a small pulley so that the cut of speed will be fast which
means the smaller the pulley, the faster of cutting hacksaw will move. It provides a vise by holding the
workpiece during cutting operation and the moving in power hacksaw moves only one direction [41]. Ikpe
Aniekan E. et al. (2019) had developed automatic cooling power hacksaw machine in a local sawmill
where coolant can be applied manually by the operator that the cutting time of average time of 40
seconds of 5.9 kg mass with average specific mechanical energy (SME) of 29 KJ/KG and average cutting
speed of 270 rpm[9]. Double acting hacksaw machine was developed by Avi Rana et al (2018) by use of
two hacksaw blades with a DC motor as a driven to machine feed the workpiece with the help of the
shaft, scotch and yoke mechanism, and slider mechanism[7]. Assistant Professor Sachin Mate had
developed a four way hacksaw machine by using four hacksaws in cutting operations where using a motor
that rotates 60 rpm with a power of 12V. The components used are 300mm length connecting rods, disc,
100 Watts Battery, Holder, and frame base[6].
2.3.2 Pedal Operated Hacksaw Machine
The Pedal Operated Hacksaw Machine allows to cut various materials aside from ferrous and non
ferrous metals without the access of electricity using pedal power. In comparison to hand operated
hacksaw, pedal operated hacksaw utilizes less human power due to the efficient use of the muscle
part[42].The Pedal Operated Hacksaw Machine is composed of a simplex chain drive for pedal power
transmission which is connected from the pedal to the flywheel. The flywheel reserves an excess amount
of energy from pedalling which is delivered when there is a deficiency in energy during the transmission
of power. This reduces fluctuation in speed on the system which smoothens the pedal during operation.
The flywheel connects the hacksaw via slider crank mechanism which converts the rotational speed of the
12
flywheel to a linear reciprocating motion or the cutting action of the hacksaw [43]. Studies related to Pedal
Operated Hacksaw Machines have been improving over the years in order to attain its output without any
losses. One of the factors to be considered is the design in which it shall be made convenient to the user
during its operation. The speed of the flywheel shall be improved in order to increase the power output of
the Pedal Operated Hacksaw Machine. To improve the rotational speed of the flywheel, the velocity ratio
of the chain drive must be increased[15]. There is a limit in terms of the velocity ratio between the two
sprockets that will lessen the pedalling time generated by the user because of fatigue[1]. In order to reduce
the pedalling effort of the user while improving the power output, a dual chain drive shall be used which
increases the velocity ratio while the proper transmission is distributed.
2.4 Operating Cost
Operating cost is the amount needed in operating an equipment. Estimating the operating cost is
important in determining the working capital of one’s company as well as start-up costs. Classifications
of operating costs include the cost of raw materials, costs of utilities and fuel, labor cost and
miscellaneous costs where taxes, corporate expenses and insurances were compensated [76]. Power
hacksawing receives an extend in competition among other cutting methods like band and circular sawing
where both of these processes have more cutting time, increasing its production. More cutting time means
more power on electric powered machines which increases the cost of operation, affecting the working
capital of the company. Reduction of costs during operation can be of high regard to manufacturers
especially to those who just started. With its simple method of cutting, reduction of the operating cost for
power hacksawing can be improved by generating power without the need of access to electricity[77].
2.5 Parameters that affect the performance of Hacksaw Machine
Power hacksaw machines may be classified according to the method used to develop load
between the blade and the workpiece during the cutting stroke. The good performance of a hacksaw
machine depends on the output of cutting speed, cutting time, cutting production, and depth of cut as well
13
as the efficiency output. With proper understanding in terms of the relation to these parameters, shop
productivity can be improved when these ideas are applied to the development of the Pedal Powered
Hacksaw[48]. Sarwar (1974) stated that in terms of specific cutting energy of metal cutting tools, the
cutting energy required to remove a unit volume of material. However, the metal removal rate is
dependent more on thrust force than cutting force[52].
2.5.1 Cutting Speed
The hacksaw velocity or the cutting speed is used to determine the output performance of the
hacksaw machine generated which is dependent on the rotational speed of the flywheel where the
hacksaw is connected using the crankshaft during pedalling[42]. The cutting speed of the Pedal Powered
Hacksaw is limited depending on the type of material to be used for the hacksaw blade which contributes
to the effect of the tool life if exceeded. High Speed Steels or HSS are common in the market today as the
material for Power Hacksaw Blades. HSS materials are able to withstand higher cutting speeds which
satisfies the performance of Power Hacksaw Machines[48]. Miller (2004) stated that there are optimal
cutting speeds for common workpieces to be cut by the Power Hacksaw Machine. The optimal cutting
speed for mild steel shall be at 130 rpm, the annealed tool steel at 90 rpm, and the unannealed tool steel at
60 rpm[47].
2.5.2 Cutting Time
The cutting time or machining time determines the amount of time for the pedal operated
hacksaw machine to cut a single workpiece. It examines the state of machinability of the pedal operated
hacksaw machine which influences the cutting capacity of the workpiece during the time of operation
affecting the cost of production. The cutting time of the Pedal Hacksaw Machine can be improved using
various approaches which were used to determine the time of its completed cutting operation. The first
approach can be based on the details of its process during cutting, the second approach is based on the
cutting path of the Pedal Operated Hacksaw Machine where its distance is used to estimate the cutting
time, and the third approach which is the approximate method that consists of the combined approach
14
between the process of the first and the second method[51]. These approaches required the theoretical
concept of the relation in terms of the cutting speed and depth of the Pedal Operated Hacksaw in order to
establish a more accurate reading of its cutting time[50]. Thompson et. Al (1979) had investigated the
sawing operation of the hacksaw comparing the cutting time of the given workpiece when sawing in an
angular motion to the conventional operation which had led to the fact that there are three factors that
should be done to improve the cutting time. The first factor states that the applied load should be
improved in terms of its effectiveness, second factor states that the relative velocity of cutting should
increase in its magnitude, and the third factor states that the hacksaw blade shall be improved such that it
can penetrate the workpiece in a much effective way[49].
2.5.3 Depth of Cut
The depth of cut measures the distance of the line of cut from the surface of the workpiece [48].
The depth of cut determines the state of the Pedal Powered Hacksaw Machine during its sawing operation
governed by two factors which are the trust load applied per hacksaw blade tooth and the chip formation
during cutting[49]. The depth of cut is proportional to the thrust force applied which is based on the weight
of the hacksaw frame such that every single tooth of the hacksaw blade shall penetrate in between ranges
of 2 - 30 μm in a single stroke during its sawing operation[52]. Another effect to be considered during the
sawing operation affecting the trust load and the depth of cut is the cutting angle in which an angular
sawing motion is applied to improve the capability of the hacksaw blade to penetrate the workpiece while
the cutting effort is reduced. The trust load shall be maintained such that the cutting force does not exceed
the breaking strength of the hacksaw blade[49]. Chips are waste materials that are formed during cutting
influenced by the shearing force of every tooth of the hacksaw blade [54]. A compressive stress is applied
by the shearing force of the hacksaw blade perpendicular to the shear plane penetrating the workpiece in
which chips are generated[55]. The ductility of the workpiece could affect the trust load based on the chip
formation shown in a test conducted by Sanwar et. Al (1974) in regards to the cutting action of the
hacksaw blade which was classified into three factors of chip formation. A ‘piling-up’ chip formation was
15
observed when sawing copper resulting in a momentary build up in the thrust force until a steady value is
observed when the chip formation is complete. This had led into a conclusion that the thrust load applied
per tooth is smaller in comparison with the total load applied on the hacksaw blade resulting in an
improved depth of cut of 0.12 mm as shown in figure 2.2[52].
Figure 2.2 Piling - up action found when sawing a copper workpiece
Discontinuous Piling-up chip formation was observed when sawing an aluminum workpiece
showing a significant increase in the initial thrust force of the hacksaw blade. There are no steady values
observed in its thrust force instead a momentary rapid increase was shown during its gradual
decomposition. This shows that due to the lack of ductility in the aluminum workpiece, a portion of the
chip was separated during the process increasing the trust load until another chip was formed[52].
16
Figure 2.3 Discontinuous Piling - up action observed when sawing an aluminum workpiece
A combination of ‘piling-up’ and discontinuous chip formation was observed when cutting a lead
workpiece showing a gradual increase in the trust load which ended in an approximate value of 72.5 lbf.
During a discontinuity in chip formation, the trust load decreases until it reaches steady state stopping the
development of contact between the chip and the tooth. The study between the three chip formations had
shown that the thrust load per hacksaw blade teeth is not consistent in relation to the depth of cut
regardless of the proportionality. This could affect the size of both the workpiece and the hacksaw blade
in which workpieces with widths smaller than the required distance of each tooth to form a chip resulting
in a depth of cut larger than the applied thrust load[52].
17
Figure 2.4 Combined Discontinuous and Piling - up action observed when sawing a lead
workpiece
2.6 Potential Contribution of the Proposed study to the Existing Body of Knowledge
The newly proposed design with a calculated improvement characteristic will be a stepping stone
for further studies of the hacksaw machine by using a pedal transmission similar to bicycle mechanism
wherein improving the performance and the efficiency of the newly designed hacksaw machine will give
information of the power output given. The pedal power, hacksaw blade, and the machine design analysis
will be the reference for further studies for the development of this different design of hacksaw machine.
The comparison between theoretical calculations and the actual will be explained in this study.
The current researchers of this study aims to modify the performance characteristics of the pedal
operated hacksaw machine using an improvised bench vice which can hold the workpiece at a different
angle setting in order for the hacksaw blade to cut at different angles. This study will be used in the
18
University of San Carlos Machine Shop since there has been no cutting machine operated by human
pedalling present yet if there is no electricity.
19
CHAPTER 3. THEORETICAL BACKGROUND
3.1 Pedal Powered Hacksaw
The Pedal Powered Hacksaw is a machine with a purpose of cutting metals, plastics and wood
without the need of electricity in order to operate. This machine is operated through manual pedalling
which produces four times the amount of power with less human effort than manual hand-cranking. The
Pedal Powered Hacksaw uses the principle of slider-crank mechanism which serves as the basic
mechanism, converting rotational motion from the pedal to linear motion of the hacksaw. By means of
chain drives, human power from the pedal is transmitted to the flywheel sustaining the power input. The
stored energy from the flywheel is transferred to the hacksaw by means of the crankshaft. The required
power output of the Pedal Powered Hacksaw does not exceed the force where human beings are capable
to exert thus it is applicable at a very low power.
3.2 Force
The activity of the pedal powered hacksaw machine is evaluated based on the concept of force. The
measurement of force constitutes to the vector quantity which is distinguished by its magnitude and
direction followed by the point of exertion towards the pedal powered hacksaw machine [70]. Newton’s
second law states that force is proportional to what is required for an object of constant mass to change its
velocity. The force can be determined by,
F = ma
(3.1)
Where m is the mass of the object, and a is the gravity of acceleration which is 9.81 m/s2. The study of the
special case of Newton’s Second Law in which the acceleration of the particle is zero is referred to as
statics[64]. Most common idealized structures fall into two-dimensional (planar) or three-dimensional
(spatial categories). In a planar structure, all forces act along a particular plane, and forces are absent in
directions perpendicular to the chosen plane. Typically, in a planar structure, if the plane is the xy-plane
then the equilibrium are,
ΣFx = 0
(3.2)
20
ΣFy = 0
(3.3)
ΣMz = 0
(3.4)
Where Fx and Fy represent forces in the x and y directions respectively and Mz represents moment of
forces about an axis perpendicular to the plane passing through a point on the plane[64]. The forces that act
on the pedal powered hacksaw machine on both x and y directions consist of external forces which
opposes the direction towards the internal forces where resistance occurs towards the cross-sectional area
of the plane where force is exerted known as stress. Represented by the symbol σ, stress is expressed as
(3.5)
where F is the force applied and A is the cross-sectional area of the plane perpendicular to the direction of
the force[15]. Stress is used to determine the stability of the pedal powered hacksaw in order to prevent
deformation in the components caused by excessive stress applied during operation. In order to maintain
the stability of the pedal powered hacksaw, the stress should not reach the value of the permissible stress
of each components of the pedal powered hacksaw depending on the material used[72].
Figure 3.1: The vector nature of a force[71]
The magnitude of the force exerted on a body depends on its direction. A single force F consists of
a horizontal force Fx and the vertical force Fy which are expressed by the following
(3.6)
(3.7)
21
(3.8)
where θ represents the angle of the direction of the force from the horizontal axis in degrees. The angular
direction of force applied on the pedal powered hacksaw changes for a period of time during its operation
from the starting point of the cutting direction of the workpiece towards its end point[71].
3.3 Chain Drive
The chain drive is a way of transmitting motion from the pedal to the flywheel in order to ensure
transmission by the chains from one sprocket to another without slippage at the same time permits higher
speeds that was caused by the additional excess power released by the flywheel. This chain is utilized as
drive, transport or conveyor chains for static or substituting loads with slow or high chain speeds
transmitting power between two equal shaft. The chains are made up of number of rigid links which are
hinged together by pin joints in order to provide the necessary flexibility for wrapping round the driving
and driven wheels. These wheels have projecting teeth of special profile and fit into the corresponding
recesses in the links of the chain as shown in Figure 3.2. The toothed wheels are known as sprocket
wheels or simply sprockets. The sprockets and the chain are thus constrained to move together without
slipping and ensures perfect velocity ratio.
Figure 3.2: Chain Drive[15]
The chains are mostly used to transmit motion and power from one shaft to another, when the center
distance between their shafts is short such as in bicycles, motor cycles, agricultural machinery, conveyors,
rolling mills, road rollers etc. The chains may also be used for long centre distance of up to 8 meters. The
chains are used for velocities up to 25 m / s and for power up to 110 kW. In some cases, higher power
22
transmission is also possible. The distance between the hinge center of a link and the corresponding hinge
center of the adjacent link is the pitch of chain. The pitch of chain shows the figure. Pitch of chain is
usually denoted by p[15].
Figure 3.3: Terms used in chain drive[15]
3.3.1 Bush Roller Chain
The bush roller chain is a power transmitting chain common for bicycle chains. It gives off a little
noise due to its simple construction which affects the impact between the tooth of the sprocket and the
rollers. The bush roller chain consists of rounded links where the bush is connected between the links and
is secured by a pin. The round construction of the chain enables the rollers to rotate on the bush,
protecting the teeth of the sprocket against wear. Bush roller chain can be applied when less lubrication is
needed[15].
23
Figure 3.4: Bush Roller Chain[15]
3.3.2 Transmitted Power
The Transmitted Power or Pedal Power is the rate of work by the user through pedalling which is
generated to the Pedal-Operated Hacksaw Machine for a period of time. The user is able to generate
power through pedalling at less effort due to the quadriceps, the largest part of the muscle, which is
responsible for pedalling movements[13]. The power through the pedal is transmitted to the sprocket D1
which serves as the driver sprocket. According to Wilson (1986), an average person generates power in a
rate of ¼ hp by pedalling for a short amount of time. This was proven by an experimental study in Oxford
that most riders had achieve a power rating similar of ¼ hp in a span of 10 mins using a dynamometer
mounted in a stationary bicycle[11].
3.3.3 Pedalling Speed
The Pedalling Speed is the rate at which the user cranks the pedal. Wilson (1986) established a
curve showing the optimal pedalling speed of the generated pedal power based on his study on Pedal
Power. Refer to this curve, a power rate of 186.5 W or ¼ hp is marked on the vertical side of the curve
which is assumed to be the Power Output. By tracing a vertical line from the intersection point between
the Power Output and the optimal curve, the pedalling rate is determined at 70 rpm[1].
24
Figure 3.5: The optimum pedalling rate over the desired power output[1]
3.3.4 Pitch
The pitch is the length between the hinge joint of a chain link. One chain link is considered as a
single pitch of the chain. The pitch is in a form of a chord due to the rigid links in a chain. Consider one
pitch length AB of the chain subtending an angle θ at the centre of sprocket (or pitch circle) as shown in
figure 3.3, the pitch of the chain is determined as
(3.9)
where D is the diameter of pitch circle, and θ is the angle at the center of the sprocket or pitch circle[15].
3.3.5 Pitch Diameter
The Pitch Diameter serves as the operating diameter of the chain sprocket. This measures the
diameter at which the center point of the hinge lie on the sprocket as shown in figure 2. The diameter of
25
the chain sprocket is based on the pitch diameter when designing for chain drives. To determine the pitch
circle diameter of the sprocket,
D=
(3.10)
Where P is the pitch and T is the teeth of the sprocket. To calculate the flank radius (r e) of the sprocket, it
determine as,
re = 0.008 d1 (T2 + 180)
(3.11)
Where d1 is the roller diameter and T is the number of teeth. To calculate the roller seating radius (r1) of
the sprocket, it determine as,
r1 = 0.505 d1 + 0.069
1
(3.12)
To calculate the roller seating angle (α), it determine as,
α = 140 -
(3.13)
where T is the number of teeth. To determine the tooth height above the pitch polygon (ha),
ha = 0.625p – 0.5d1 +
(3.14)
where T is the number of teeth, p is the pitch, and d1 is the roller diameter. The figure 3.6 below shows
the tooth profile of the sprocket and figure 3.7 shows the rim profile of the sprocket.
Figure 3.6 Tooth Profile of the Sprocket[15]
26
Figure 3.7 Rim Profile of the Sprocket[15]
To calculate the top diameter (Da) of the sprocket, it determine as,
Da = D + 1.25p – d1
(3.15)
Where D is the pitch diameter, p is the pitch and d1 is the roller diameter of the sprocket. To calculate the
root diameter (Df) of the sprocket, it determine as,
Df = D – 2ri
(3.16)
Where ri is the roller seating radius. To calculate the tooth width (bf1) of the sprocket, it determine as,
bf1 = 0.93 b1 when p ≤ 12.7 mm
(3.17)
where the pitch (p) should be less than 12.7 mm which is applicable for bicycle chains[15].
3.3.6 Sprocket Tooth
The Sprocket Tooth is the part where the chain link and the sprocket came in contact during
transmission. This prevents slippage in between the sprocket and the chain, negating losses during
transmission. Based on figure 3.3, the number of teeth on a single sprocket is determined by
(3.18)
Where
is the pitch angle, 360 is the total angle of 1 revolution, and T is the number of teeth on
the sprocket. To ensure smooth operation during transmission of the chain drive, the minimum number of
27
teeth is determined on the driven sprocket which is the smaller sprocket. Provided by the table below, the
number of teeth of the smaller sprocket for roller chain is determined[15].
Number of teeth at velocity ratio
Type of
Chain
1
2
3
4
5
6
Roller
31
27
25
23
21
17
Silent
40
35
31
27
23
19
Table 3.1 Number of teeth on the smaller sprocket[15]
3.3.7 Characteristics of Roller Chain
The pitch, roller diameter, width between the inner plates, the transverse pitch and the breaking
load can be determined by knowing what size of chain is used. Various standards for roller chains were
established in order for manufacturers to cater in the market. Based on the Indian Standard (IS: 2403 —
1991), the various characteristics for the roller chains are given in the following table[15].
05 B
8.00
5.00
Width
between
inner
plates (b1)
mm
Maximum
3.00
06 B
9.525
6.35
5.72
10.24
8.9
16.9
24.9
08 B
12.70
8.51
7.75
13.92
17.8
31.1
44.5
10 B
15.875
10.16
9.65
16.59
22.2
44.5
66.7
12 B
19.05
12.07
11.68
19.46
28.9
57.8
86.7
16 B
25.4
15.88
17.02
31.88
42.3
84.5
126.8
ISO Chain
number
Pitch (p)
mm
Roller
diameter
(d1) mm
Maximum
Breaking Load (kN)
Minimum
Transverse
pitch (p1)
mm
Simple
Duplex
Triplex
5.64
4.4
7.8
11.1
28
20 B
31.75
19.05
19.56
36.45
64.5
129
193.5
24 B
38.10
25.40
25.40
48.36
97.9
195.7
293.6
28 B
44.45
27.94
30.99
59.56
129
258
387
32 B
50.80
29.21
30.99
68.55
169
338
507.10
40 B
63.50
39.37
38.10
72.29
262.4
524.9
787.3
48 B
76.20
48.26
45.72
91.21
400.3
800.7
1201
Table 3.2: Characteristics of roller chains according to IS: 2403 — 1991[15]
3.3.8 Velocity Ratio (Sprockets)
The velocity ratio of the sprockets describes the relationship between the driver sprocket and the
driven sprocket. The velocity ratio is expressed by
(3.19)
where N1 represents the speed of the driver sprocket and N2 represents the speed of the driven sprocket in
rpm. The diameter of the driven sprocket and the number of teeth of the driver sprocket can be identified
if the velocity ratio of the sprockets is determined.
(3.20)
where D1 represents the pitch diameter of the driver sprocket, D2 represents the pitch diameter of the
driven sprocket, T1 represents the number of teeth from the driver sprocket and T 2 represents the number
of teeth from the driven sprocket[15].
The driven sprocket should be smaller than the driver sprocket in order to transmit power greater
than the power input. In order to identify the velocity ratio of the sprockets, N2 is determined by the
power rating of a selected chain size provided in the table below[15].
29
Power (kW)
Speed of
smaller
sprocket or
pinion (r.p.m)
06 B
08 B
10 B
12 B
16 B
100
0.25
0.64
1.18
2.01
4.83
200
0.47
1.18
2.19
3.75
8.94
300
0.61
1.70
3.15
5.43
13.06
500
1.09
2.72
5.01
8.53
20.57
700
1.48
3.66
6.71
11.63
27.73
1000
2.03
5.09
8.97
15.65
34.89
1400
2.73
6.81
11.67
18.15
38.47
1800
3.44
8.10
13.03
19.85
-
2000
3.80
8.67
13.49
20.57
-
Table 3.3: Power rating of a simple roller chain in rpm[15]
3.3.9 Center Distance
The center distance (x) of the chain drive measures the length between the center points of the two
sprockets as shown in figure 3.8.
Figure 3.8: Center Distance of the Chain Drive[15]
According to Khurmi (2005) the minimum center distance of the chain drive must be in between 30
to 50 times the pitch in order to achieve best results. A tightened chain increases the chance of wearing
30
between the rollers. To counter this problem, initial sagging or loosening of chains must be
accommodated through the value obtained at the center distance of the chain subtracted by a range of 3 to
5 mm. To determine the center distance of 2 sprockets, it can be defined by,
X = 40p
(3.21)
Where p is the pitch of the chain. Consider the initial sag in the chain, thus the center distance is reduced
by 2 to 5mm. The correct center distance of 2 sprockets is defined by,
X2 = X – X1
(3.22)
Where X is the center distance of 2 sprockets, and X1 is the center distance which is reduced by 2 to 5mm
by the initial sag in the chain[15].
3.3.10 Length of Chain
An open chain drive systems connecting the two sprockets is shown in figure. The length of chain
is used for calculating the distance between the 2 sprockets connecting in the chain drive as shown in
figure 3.8. The length of the chain (L) is equal to the product of the number of chain links (K) and the
pitch of the chain (p). The length of chain is determined as,
L = Kp
(3.23)
where the number of chain links (K) is determined by,
(3.24)
where T1 is the number of teeth on the smaller sprocket, T2 is the number of teeth on the larger sprocket, x
is the center distance of connecting 2 sprockets, and p is the pitch of the chain[15].
3.3.11 Pitch Line Velocity
The pitch line velocity measures the speed of the sprocket along its pitch diameter which varies
from maximum to minimum at every cycle of tooth contact. This affects the chain transmission that
would result to corresponding losses. To counteract this problem, the angle
should be reduced to make
the transmission smooth. Another alternative is to determine the number of teeth on the smaller sprocket
31
at table 1 which reduces the variation of speed at the right angle . The average pitch line velocity is
determined by
(3.25)
where D is the pitch diameter of the sprocket and N is the speed of the sprocket[15].
3.3.12 Service factor
The service factor (Ks) is the ratio of the power rated to the power transmitted expressed by the
product of various factors on the chain drive[15].
(3.26)
The load factor (K1) determines the load applied on the chain drive[15].
Load
Load Factor
Constant
1
Variable, mild
1.25
shock
Heavy shock
1.5
Table 3.4: Load factor of chain drives[15]
The lubrication factor (K2) determines the amount of lubrication applied on the chain drive[15].
Lubrication Applied
Lubrication factor
Continuous
0.8
Drop Lubrication
1
Periodic
1.5
Table 3.5: Lubrication factor of chain drives[15]
32
The rating factor (K3) determines the period of operation of the pedal-powered hacksaw[15].
Period of Operation
Rating factor
8 hours per day
0.8
Drop Lubrication
1
Periodic
1.5
Table 3.6: Rating factor of chain drives[15]
3.3.13 Design Power
Design power or rated power is the output power transmitted by the chain drives which is
expressed as the product of the power transmitted at the pedal and the service factor[15].
(3.27)
3.3.14 Load of Chain
The load of the chain measures the load that is transmitted by the chain drive which is equal to the
tangential driving force of the chain expressed by
(3.28)
where W represents the load transmitted by the chain, FT represents the tangential driving force and V is
the pitch line velocity. The breaking strength of the chain measures the load required to break the chain.
According to Khurmi (2005), the breaking strength of a roller chain is obtained using the empirical
relation of
(3.29)
where WB represents the breaking strength of the chain and p represents the pitch of the chain[15].
33
3.3.15 Factor of Safety
The factor of safety determines the scale at which the load transmitted by the chain drive does not
break overtime during operation. This is expressed by the ratio between the breaking load of the chain and
the load transmitted by the chain[15].
(3.30)
3.4 Shaft
The shaft is a part of the pedal-powered hacksaw machine which transmits power from the driver
sprocket to the driven sprocket and the flywheel. The shaft is designed to withstand the torque between
the driver and the driven part. The shaft design is based on the formula in which the solid shaft is
subjected to the twisting moment or torque only
(3.31)
Where T is the torque subjected on the shaft, τ is the shear stress on the shaft and d s is the shaft diameter.
According to the ASME code, the maximum permissible shear stress of the shaft with no keyway
allowance is taken as 56 MPa[15]. The maximum stress (tensile or compressive) is given when the shaft is
subjected to a bending moment only by the bending equation. The bending moment of the shaft is
determined by,
(3.32)
where M is the bending moment of the shaft, σ is the stress permissible during bending, y represents the
length of the shaft and I which is the moment of cross-sectional area of the shaft about the axis of rotation
expressed by the equation.
(3.33)
The weight of the flywheel is based on the bending moment of the shaft. With the opposite side of the
shaft as the reference point, the weight of the flywheel is expressed by,
34
Wf =
(3.34)
Where M is the bending moment of the shaft and y is the length of the shaft. The mass of the flywheel mf
is converted from the weight of the flywheel based on newton’s second law of motion
mf =
where 9.81 represents the value of acceleration due to gravity with the unit m/s2 [15].
3.5 Flange Coupling
A flange coupling is used to align the two shafts that separates the 4th sprocket to ensure proper
distribution of mass within the shaft followed by more convenient maintenance. With its uncomplicated
structure and lesser price, flange couplings are suitable for low cost projects[72]. In this process, the iron
flange is installed at one end of each of the two shafts attached by nuts and bolts. Four or six bolts are
used to connect two flanges depending on the amount of torque applied on the shaft [15]. A gap is ensured
between the flange coupling in order to provide room for the 4th sprocket to operate.
Figure 3.9: Flange coupling[72]
The flange coupling is designed to ensure proper connection with the shafts without failure. The
following proportions required for the coupling hub are based on the shaft diameter ds which is
determined using equation 3.31[15].
35
(3.35)
(3.36)
Where dch is the diameter of the coupling hub and lch is the length of the coupling hub. The flange is
designed to prevent collision from the chain as well as no deformation occurs that can hinder the
performance of the shaft during transmission. The required proportion of the flange thickness is
determined using the shaft diameter ds[15].
(3.37)
Where tfl is the thickness of the flange. Selection of bolts for the flange coupling shall be made to
withstand the shear stress Ss made during shaft transmission which is determined by the equation[15].
(3.38)
Where Fb is the load of each bolt during transmission followed by the bolt size db. The required number
of bolts that are attached to a pair of flange coupling depends of the size of the bolt, the diameter of the
bolt circle Dcb and the torque applied on the shaft expressed by this equation[15].
(3.39)
Where the compressive stress of the bolts σcb is associated with the load on each bolt based on the
formula[15].
(3.40)
The minimum number of bolts is expressed by combining the equations 3.39 and 3.40[15].
(3.41)
The shear stress Ssb is induced on the bolts caused by the shaft during transmission. Shear stress on the
bolts is expressed by this equation[15].
(3.42)
36
Where the load Fb is subjected perpendicular to the resisting area of each bolt[15]. By combining the
equations 3.41 and 3.42, the minimum number of bolts required for the flange coupling results to this
equation[15]
(3.43)
The standard number of bolts required to be attached in a flange coupling are 3, 4, 6 and 8 bolts[15].
3.6 Flywheel
A flywheel used in machine serves as a reservoir which stores energy during the period when the
supply of energy is more than the requirement and releases it during the period when the requirement of
energy is more than supply. Figure below shows the parts associated in the flywheel.
Figure 3.10: The flywheel[15]
In machines where the operation is intermittent like punching machines, shearing machines,
riveting machines, crushers and etc., the flywheel stores energy from the power source during the greater
portion of the operating cycle and gives it up during a small period of the cycle. Thus, the energy from the
power source to the machines is supplied practically at a constant rate speed of flywheel will decrease, it
gives up energy[57]. Based on this concept, the mass (m) of the flywheel is expressed as
m = π R2 t ρ
(3.44)
Where R is the radius of the rim, t is the thickness and ρ is the density of the material of the flywheel[15].
37
3.6.1 Velocity Ratio (Flywheel)
The velocity ratio of the flywheel is used to determine the radius of the flywheel by the length of
the driver pedal. The velocity ratio of the flywheel is determined as[15]
(3.45)
3.7 Mechanical Advantage
Mechanical Advantage is the ratio between the load over the effort applied on the pedal-powered
hacksaw. One of the basic concepts for Mechanical Advantage is the torque which increases when the
distance of the force applied to the axis becomes greater. The lever, one of the simple machines, serves as
the basic concept for the Mechanical Advantage in which the load at point A is lifted by the force exerted
at point B about a fixed point F or the fulcrum[15].
Figure 3.11: Free body diagram of a simple lever[15]
Based on the figure given, the Mechanical Advantage is expressed as:
(3.46)
where the ratio between the lever arms l2/l1 is called leverage[15].
Mechanical Advantage is applicable for chain drives due to the primary function of the sprockets
which transmits torque by the chains. Mechanical Advantage of the sprockets is gained based on the
difference between the pitch diameters. If the velocity ratio of the sprockets is at 1:1 where the amount of
torque transmitted from the driver sprocket is equal to the driven sprocket, no Mechanical Advantage is
obtained on the chain drives. By decreasing the pitch diameter of the driven gear, the Mechanical
38
Advantage is gained due to the amount of torque transmitted on the smaller sprocket by the driver
sprocket[59].
3.7.1 Ideal Mechanical Advantage
Ideal mechanical advantage is the ratio of the load over the applied effort based on the construction
of the machine. The effort is produced on the pedal which is connected to the driver sprocket. The driver
sprocket then transmits torque towards the smaller sprocket via chains. The ideal mechanical advantage of
the pedal-powered hacksaw machine is expressed as
(3.47)
Where D2 is pitch diameter of the driven sprocket and D1 is the pitch diameter of the driver sprocket.
Since the formula of the IMA is similar to the velocity ratio of the sprocket therefore IMA and the
Velocity Ratio are equal[61].
3.8 Slider Crank Mechanism
The pedal controls the hacksaw through the slider crank mechanism which converts the rotating
motion of the pedal to horizontal reciprocating motion of the hacksaw[68]. The slider crank mechanism of
the pedal power hacksaw is composed of three connecting rods in which one connecting rod is connected
to the flywheel as a crank while the other connecting rods are connected to the hacksaw as a slider.
39
Figure 3.12: Slider Crank Mechanism of the Pedal Powered Hacksaw[68]
The velocity of the slider in the slider crank mechanism is determined by using the relative velocity
method which is a type of graphical method which is simple and requires a great level of accuracy when
sketching a velocity polygon[68]. In order to achieve this requirement, the use of a CAD software is
essential in this process. Each of the components of the slider crank mechanism were determined in terms
of its type of motion. Starting from the crank which identifies the rotating motion of the mechanism, the
velocity from the point A is expressed as
(3.48)
where r is the radius of the crank and ω is the angular velocity of the flywheel. The velocity of the slider
B which identifies the reciprocating motion of the mechanism, is expressed as
(3.49)
where VB/A is the magnitude of the velocity perpendicular to the direction of the velocity of the slider B
which is expressed in terms of graphical approach
Figure 3.13: Graphical representation of eqn 3.35[68]
in which VB/A should be perpendicular to the direction of the velocity of the crank V A which starts from
the fixed point O. The velocity of the slider VB should be connected from the end of the magnitude of
velocity VB/A to the fixed point O[69]. The magnitude of each velocity is determined by using the velocity
scale in which the value of the magnitude is represented by the length of the graphical approach[68].
40
3.9 Connecting Rod
A connecting rod is a machine part that converts rotating motion from the flywheel to reciprocating
motion of the hacksaw by coupling from one link to another, exposing to alternating compressive and
tensile forces. The safe value for the cross-sectional area of the connecting rod is determined through
assumption of the bending moment M subjected by the pins connected from each of the machine parts.
(3.50)
where I represent the moment of inertia of the cross-sectional area of the connecting rod. The moment of
inertia refers to the point at which all of the forces gather during its motion depending on the shape of the
cross-sectional area[64].
Figure 3.14: Moment of inertia of a (a) rectangular cross-section and a (b) circular cross-section[15]
The moment of inertia of a rectangular connecting rod in respect to the x-axis is expressed as:
(3.51)
where b is the width of the connecting rod and h is the depth of the connecting rod [15]. The moment of
inertia of a rectangular connecting rod in respect to the y-axis is expressed as:
41
(3.52)
The moment of inertia of a circular connecting rod in respect to both axis is expressed as:
(3.53)
where d is the diameter of the connecting rod. During motion, an axial load of alternating compressive
and tensile forces is subjected to the connecting rod causing its sudden change of shape known as
buckling[15].
Figure 3.15: Buckling of connecting rod[15]
Scottish engineer William John Rankine established an empirical formula which correlates the buckling
load obtained by Euler’s formula after many trials observed in his experiment[15]. The resulting formula is
expressed as
(3.54)
where Wcr represents the buckling load.[15] The ultimate crushing load of the material Wc is expressed as
the product of the crushing stress and the cross-sectional area of the connecting rod
(3.55)
where the permissible crushing stress of the material to be used is shown in the table below according to
Khurmi (2005).
S. No.
Material
σc (MPa)
1.
Wrought Iron
250
a
42
2.
Cast Iron
550
3.
Mild Steel
320
4.
Timber
50
Table 3.7: Permissible crushing stress and rankine’s constant for various materials[15]
The buckling load WE is obtained by according to Euler’s theory described by the equation
(3.56)
where E is the modulus of elasticity and L represents the length of the connecting rod[15]. By substituting
eqn (3.54), the buckling load Wcr is simplified as
(3.57)
using eqns (3.55) and (3.56), the simplified value of the buckling load is expressed as
(3.58)
where Rankine established a constant based on the outcome of his experiments, the Rankine’s constant a
indicated at table 3.8 is expressed by this equation
(3.59)
using eqn 3.59, the buckling load is simplified as
(3.60)
where the radius of gyration k on the connecting rod is expressed by this equation[15]
43
(3.61)
The pin of the connecting rod is welded to a flywheel which provides a greater efficiency in terms
of strength. In this process, Shielded Metal Arc Welding is commonly used during fabrication which uses
a consumable welding material coated with a flux that protects the weld from harmful amounts of oxygen
and nitrogen preventing contamination. The minimum size of the weld is estimated to be more prominent
than the thickness of the flywheel suggested by the table below[15].
Thickness of plate (mm)
3-5
6-8
10 - 16
18 – 24
26 – 55
Over 58
Minimum size of the weld (mm)
3
5
6
10
14
20
Table 3.8: Recommended minimum size of welds[15]
Stresses for welded joints depends on what type of welded joints is used. The fillet joint is the type
of welded joint in which the welded edges of the connecting pin is overlapped. This type of welded joint
ensures the strength of the weld between the pin and the flywheel during operation. The connecting rod is
attached to a pin which serves as a movable joint where equal distribution of weight is applied by the
connecting rod throughout the pin. The length of the pin is equal to the diameter of the pin dp which is
determined through this formula:
(3.62)
where σb is the recommended bending stress of 80 MPa for the welded material with fillet welds while M
is the bending moment of the rod and s is the size of the weld[15].
3.10 Hacksaw
The Hacksaw is a cutting tool originally designed to cut metals. Development of the hacksaws was
dated back in 1880s to counteract the inefficiencies of the Star Saw which requires re-sharpening during
metal sawing. George N. Clemson, founder of the Clemson Bros. Inc, had conducted several tests to
improve the efficiency of the saw through various heat treatments, optimal dimensions, optimum teeth
shape, and various styles of set. From the resulting experiment, the blade is able to cut 387 pieces of one
44
by one inch sheet metal which concludes the improvement of the Star Saw. Clemson had also developed
the first powered hacksaw machine in 1884 which was used to test with the experimented hacksaws. It
was found out that the Star Saw that was mounted in the machine was able to cut twelve pieces of one by
one inch of sheet metal before it was being resharpened. Star Saws were improved over the years after
Clemson’s death which were now known today as Hacksaws[18]. The Hacksaw is composed of two main
parts namely the frame and the blade which carries on two different roles.
3.10.1 Hacksaw Frame
The Hacksaw Frame is a C-shaped support which holds the slender, fine-tooted saw to prevent
bucking during operation. The frame consists of head, handle, and backbone which compensate different
stresses that occur in the hacksaw blade due to the force when cutting. Most of the stresses occur in the
backbone of the hacksaw frame due to the tensile load on the hacksaw. The following stresses that
occurred in the backbone are composed of bending and axial compressive stresses[45].
Figure 3.16: Parts of the Hacksaw[45]
The hacksaw blade is mounted on the frame which is connected by two attachment pins or stud in
case of necessary replacement during breakage or wearing of the blade which loses its cutting ability. The
studs are attached on the head and on the left most edge of the handle supporting the hacksaw blade
during operation[63].
45
3.10.2 Hacksaw Blade
Hacksaw blades are thin, fine-toothed saw blades that are made to cut ferrous and non-ferrous
metals. Made from alloy steels and high speed steels, Hacksaw Blades are manufactured according to the
set of standards given in terms of shape and size. Dimensions of the hacksaw blade are measured in terms
of its length, width, thickness, pitch, no. of teeth, and the pinhole diameter[58].
Figure 3.17: Parts of the Hacksaw Blade[58]
46
Hacksaw Blades come in two different classifications which are applicable for Hand Hacksaws and
Machine Hacksaws. Hand Hacksaw blades are thinner and shorted in length due to the limit of force
exerted by the user during manual operation while Machine Hacksaw blades are thicker and longer in
length prevent further wear and breakage during operation[75]. Pedal Power Hacksaw blades follow the
standard for Machine Hacksaw blades which are determined in terms of the following set of dimensions
given for alloy steel and high speed steel type[58].
Table 3.9: Standard Dimensions for Machine Hacksaw Blades[58]
47
3.10.3 Theory on Metal Cutting
The concept of metal cutting refers to the analysis of the force in two-dimensional plane acting by
the cutting tool during shearing operation. Metal cutting is determined by the rake angle α which
measures the angle of the blade in respect to the vertical axis and the relief angle which is the angle
between the cutting tool and the surface of the workpiece after cutting[54]. The cutting action of the
hacksaw blade moves along with its rake angle which is in contact with the surface of the workpiece that
lies in the backwards direction of the stroke at which the rake angle of each tooth of the hacksaw blade is
negative[52].
Figure 3.18: The system of forces acting by the cutting tool during the cutting process[52]
3.10.3.1 Cutting Force
The cutting force Fc is used to measure the force of the hacksaw which is done in a single stroke.
The cutting force is influenced by the force transmitted on the flywheel in which the amount of work done
during cutting is evident[54]. As a function of position, the cutting force varies along with the direction of
the stroke travelled by the hacksaw between two points[64].
3.10.3.2 Trust Force
The trust force Ft is the vertical force done by the hacksaw during cutting. Influenced by the weight
of the hacksaw frame, no work is done by the trust force but causes deflections on the hacksaw blade
48
when paired along with the cutting force[54]. The trust force depends on the hardness of the workpiece
used but increases its magnitude when the weight of the hacksaw frame is increased.
3.10.4 Number of Strokes
The Number of Strokes is used to evaluate the cutting performance of the pedal-operated hacksaw
to a specific material. Based on the concept of the slider-crank mechanism in which the power from the
pedal is transmitted to the flywheel, the rotation of the flywheel is converted to linear motion of the
hacksaw via the crank shaft which serves as the stroke[33]. The number of times at which the hacksaw
travels from TDC to BDC counts as the number of strokes until the hacksaw fully cuts the material.
Previous researches related to pedal-operated hacksaws proved that the number of strokes is relative to
the cutting time and increases with the hardness of the material used to cut. In order to determine the
number of strokes it takes for a hacksaw to cut the material, the formula was being derived based on the
design of the Pedal-Operated Hacksaw
σ
(3.63)
Where σ is the number of strokes, N is the speed of the flywheel at rpm, t is the cutting time at mins and v
is the velocity of the hacksaw at m/s. For every stroke of the hacksaw is equivalent to the cutting length or
the length of contact of the hacksaw blade to the workpiece. The output speed of the pedal powered
hacksaw is determined in strokes per minute where a single revolution is equivalent to two strokes based
in the equation below.
No = 2DN
(3.64)
Where D is the diameter of the crank at m and N is the speed at rpm. The unit of the output speed is
determined as spm or strokes per minute.
3.10.5 Cutting Time
The cutting time is the amount of time it takes for a pedal-operated hacksaw to cut a specific
material. The cutting time is relative to the number of strokes of the pedal-operated hacksaw in which the
value increases for harder workpiece.
49
3.10.6 Net Power
The net power determines the amount of work that is consumed by the hacksaw on the workpiece
during cutting. The net power is expressed by this equation
(3.65)
where Fc represents the cutting force and V represents the velocity of the hacksaw at m/s. Along with the
function of position between two points, the cutting force also represents the function of the hacksaw
blade with respect to its geometry, the workpiece to be used, and the process variables which becomes
difficult to determine the exact value of the power required for the pedal powered hacksaw[54]. The net
power required by the hacksaw comes in ranges from the hardest workpiece to softest workpiece to be
cut.
3.11 Efficiency
Efficiency is the faction of the power transmitted from the source spent by the transmitted power
on the output. By efficiency, the performance of the Pedal-Operated Hacksaw is determined. Efficiency is
expressed by the ratio of the power output to the power input represented by percentage[15].
(3.66)
3.11.1 Mechanical Efficiency
The mechanical efficiency of the pedal-powered hacksaw machine determines the performance of
the transmission of power between the input power and the output power. The mechanical efficiency of
the pedal-powered hacksaw is expressed as
(3.66)
where IMA is the ideal mechanical advantage and VRflywheel is the velocity ratio of the flywheel.
50
3.11.2 Overall Efficiency
The overall efficiency is the ratio of power produced by a human driving the pedal over the power
requirement of the pedal powered hacksaw as the power output. The overall efficiency of the PedalOperated Hacksaw is determined as
(3.67)
51
CHAPTER IV: METHODOLOGY
4.1 Flow of the Study
The study involves the analysis and design of the pedal operated hacksaw machine through the
design calculations of each components and actual testing of the machine. The fabricated pedal operated
hacksaw machine will be tested under the testing parameters only in order to determine its overall
performance. The flow of the study is shown in figure 4.1 below.
Figure 4.1 Flow of the Study
52
4.2 Design Conceptualization
The design parameters of the pedal operated hacksaw machine were based from the actual testing
in cutting the workpiece that the thickness of the material was limited only at 90mm. The type of
materials to cut were wood lumber, engineering plastic and mild steel. The time to achieve in cutting is
maximum 3 minutes for all the materials to be cut.
4.2.1 Designing the Pedal Operated Hacksaw Machine
Designing the pedal operated hacksaw machine was one of the important cutting machine of
modern hacksaw machine technology. Professionals strive to design hacksaw machine that reduce human
efforts, save electricity and cutting time at working place. In this study, a Pedal Powered Hacksaw
machine design was fabricated and tested in order to determine its performance. Figures below shows the
design of the Pedal Powered Hacksaw Machine in isometric view in fig. 4.2 and the exploded view of the
Pedal Powered Hacksaw Machine in fig. 4.3.
Figure 4.2 Pedal Operated Hacksaw Machine Isometric View
53
Figure 4.3 Pedal Operated Hacksaw Machine Exploded View
Table 4.1 below shows the corresponding parts needed in the fabrication of the pedal operated
hacksaw machine. These parts will be present in all the pedal operated hacksaw machine designs.
Table 4.1 Exploded View Parts
Item Number
Parts/Components
1
Sprocket A
2
Sprocket B
3
Sprocket C
4
Sprocket D
5
Chain Drive A
54
6
Chain Drive B
7
Flywheel Pin Ball Bearing
8
Bicycle Hub
9
Shaft C
10
Flywheel
11
Connecting Rod A
12
Connecting Rod B
13
Connecting Rod C
14
Hacksaw Frame
15
Pillow Block Bearing
16
Connecting Rod Spacer
17
Hacksaw Frame Holder
18
Handlebar
19
Handlebar Stem
20
Handlebar Grip
21
Spool
22
Saddle Set
23
Workpiece Mounting Platform
24
Sprocket A Crank set
25
Threaded Stem Caster Wheel with wheel brake
26
Flange Bolt
27
Bicycle Frame Lockscrew
28
Bench Vise Stationary Jaw
29
Bench Vise Sliding Jaw
30
Bench Vise Handle
31
Bench Vise Screw
32
Bench Vise Screw Mounting Plate
33
Hacksaw Blade
34
Hacksaw Frame Spacer
35
Stationary Jaw T-bolt
36
M5 Allen Screw
37
M6 Flange Hex Screw
38
M6 Flange Hex Nut
39
Machine Body
55
40
M8 Hex Screw
41
M8 Hex Nut
42
M8 Blade Washer
43
M12 Hex Screw
44
M12 Hex Nut
45
M12 Washer
46
M16 Flywheel Pin Hex Nut
47
M20 Hex Nut
48
M20 Flange Hex Nut
49
M10 Hex Screw
50
M10 Hex Nut
51
Spool Ball Bearing
52
Saddle Sliding Mounting Bar
53
Seat Post
54
Stem Post
4.2.2 Design Calculation of Sprockets
The sprocket is one of the main parts to cut the material in hacksaw by pedaling, it contributes to
maximize the speed of the hacksaw and consume time in cutting the material. Sprockets are used to
transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a
track, tape and etc. This sprocket is very important to calculate the number of teeth and diameter because
it is one of the factors that improve the efficiency of the hacksaw machine. In this study, four sprockets
are proposed in order to determine the maximum speed and its performance at different diameter of
sprockets and the number of teeth.
56
Sprocket A
Sprocket B and C
Sprocket D
Figure 4.4 Sprockets
4.2.2.1 Design Calculation of Sprocket A
Sprocket A is the largest diameter and smallest speed of all four sprockets. This connects to the
pedal crank which is the driver where the user produces a pedal power of ¼ hp at a rate of 70 rpm
according to Wilson (1986). The standard chain for a bicycle is 08B along with its rated power of 0.64
kW, the number of teeth for the smaller sprocket of 27 and the speed of the smaller sprocket of 100 rpm
which is from the table 3.3. By using the velocity ratio which is the ratio between the speed of the smaller
sprocket B and the sprocket A, the number of teeth of the sprocket A is 39 teeth. By using equation 3.10
along with the number of teeth of the sprocket A and the pitch of 12.7, the diameter of the sprocket A is
157.83 mm.
4.2.2.2 Design Calculation of Sprocket B
Sprocket B connects to shaft A. The sprocket A and sprocket B are connected to the chain drive in
which the sprocket B is the driven. The sprocket B is the second largest diameter and smallest speed of
four sprockets. To calculate the diameter, number of teeth and the speed of sprocket B, use the equation
3.10 by substitute the diameter of sprocket A and also the velocity ratio, the diameter of sprocket B is
calculated as 109.395 mm. The number of teeth and speed of sprocket B is determined by using equation
3.20 which substitutes the velocity ratio and the number of teeth in sprocket A in order to get the number
57
of teeth in sprocket B. The same equation is used to determine the speed at sprocket B by substituting the
speed of sprocket A. The number of teeth and speed of sprocket B is 27 teeth and 100 rpm.
4.2.2.3 Design Calculation of Sprocket C
Sprocket C connects to shaft A which means that the sprockets B and C is align at the shaft. The
sprocket B and the sprocket C have the same diameter, number of teeth and the speed. The second chain
drive is connected via sprockets C and sprocket D which transmits power from the first chain drive.
4.2.2.4 Design Calculation of Sprocket D
Sprocket D is aligned at flywheel and is connected to the shaft B. In order to determine the speed,
diameter and the number of teeth of sprocket D, the sprocket D is calculated to be 200 rpm, 81.184 mm,
and 20 teeth by using the equation 3.10, 3.19 and 3.20. Therefore, sprocket D is the smallest speed of all
the four sprockets and this sprocket will give the speed to the shaft B and flywheel.
The maximum speed of the sprocket varies by calculating the smallest diameter of the four
sprockets. The smallest sprocket is aligned with the flywheel and the shaft B. These four sprockets
support the two chain drives. The calculations of the chain drives are shown in Appendix A using
equations 3.27, 3.28, 3.29 and 3.30. The table 4.2 below shows the calculations of diameter, number of
teeth and the speed of the four sprockets.
Table 4.2 Dimensions of 4 Sprockets
Sprocket
Diameter
Number of Teeth
(mm)
Speed
(rpm)
A
157.83mm
39 teeth
70 rpm
B
109.395mm
27 teeth
100 rpm
C
109.395mm
27 teeth
100 rpm
D
81.184mm
20 teeth
200 rpm
58
4.2.3 Design Calculation of Chain Drives
The chain drive transmits power through the four sprockets. This design consists of two chain
drives. The chain drive is one of the important parts to rotate the four sprockets and maximize also the
speed. The design of chain drives is to compensate the power rating during the transmission of the pedal
power hacksaw. To ensure the fit of the chain, the sprocket is to determine based on the velocity ratio
needed to operate the pedal powered hacksaw. When the specification of the sprocket is identified, the
load of the first chain drive can be determined based on equation 3.28, which is calculated to be 325.47N.
The factor of safety of the first chain drive is calculated using equation 3.30 which is determined to be 53.
The center distance of the first chain drive is to be calculated 508mm using equation 3.21. Considering
the initial sag in the chain, thus the center distance is reduced by 2 to 5mm. In order to determine the
corrected center distance of the first chain drive, the minimum center distance obtained is subtracted to
the initial sag range which is 504mm. The number of chain links is calculated to be 113 links by the
equation 3.24. Then the length of the chain is calculated to be 1435.1mm using equation 3.23.
Dimensions of the second chain drive can be determined based on the speed, teeth and pitch line
velocity of the sprocket D. Since the speed of the sprocket D is 200 rpm, the number of teeth is 20 and the
pitch line velocity is 0.850 m/s, the load of the second chain drive is calculated to be 1388.24 N by the use
of equation 3.28. The factor of safety of the second chain drive is calculated using equation 3.30 which is
determined to be 12. The center distance of the second chain drive is to be calculated 444.5mm using
equation 3.21. Considering the initial sag in the chain, thus the center distance is reduced by 2 to 5mm. In
order to determine the corrected center distance of the second chain drive, the minimum center distance
obtained is subtracted to the initial sag range which is 440.5mm. The number of chain links is calculated
to be 100 links by the equation 3.24. Then the length of the second chain is calculated to be 1270mm
using equation 3.23.
59
Table 4.3 Chain Drive Dimensions
Chain Drive
Load of the
Factor of
Center
Corrected
Chain links
Length of
Chain
Safety
Distance
Center
the Chain
(W)
(F.S)
Distance
(L)
A
325.47 N
53
508mm
504mm
113 links
1435.1 mm
B
1388.24 N
12
444.5mm
440.5mm
100 links
1270mm
4.2.4 Design Calculation of Shafts
This design consists of 2 shafts. Shaft A transmits power from the 2nd sprocket to the 3rd sprocket
while shaft B transmits power from the 4th sprocket to the flywheel. In order to convert mechanical energy
to electrical energy, the 2 shafts are subjected to twist and shear stress as the flywheel and sprockets
rotates. The diameter of shaft A and shaft B are different but in the same length. Both shafts have a
keyway allowance with a maximum shear stress of 42 MPa. Components within shaft A are composed of
the 2nd and 3rd sprockets of equal sizes with a bore diameter of 34 mm. The minimum diameter of shaft A
is based on the torque done by the driver sprocket which is the 2nd sprocket determined by multiplying the
tangential force and its radius. The tangential force of the 2nd sprocket is 2,059.34 N which is determined
by dividing the design power of the chain drive with its pitch line velocity. The minimum diameter of the
shaft is determined at 23.9 mm. It is safe to assume that the diameter of shaft A is 34 mm which fits on
the hub of the bike.
Components within shaft B are composed of a flywheel, sprocket, two gate bearings and a pair of
flange coupling. The torque acting on the 4th sprocket is determined by multiplying its tangential driving
force over its pitch diameter having a total of 56.35 N-m. The torque is used to determine the minimum
diameter required for the shaft. By using eqn 3.31, the minimum diameter required for shaft B is 18 mm
or 0.866 inches. Refer to the shaft size standards (ISO/R773), the design of the solid shaft shall be greater
60
than 22 mm or 1 in which is safe to assume that the diameter for the shaft B is 25.4 mm or 1 inch which
fits the bore of both flange couplings and gate bearings. For proper weight distribution, shaft B is divided
into two parts of different lengths separated by a flange coupling. The flange coupling locks both the shaft
and the sprocket in place for maintenance purposes. Shaft B1 is connected to a flange coupling and the
flywheel with a length of 136 mm and a bending moment of 25,239.17 N-mm. Shaft B2 is connected to a
flywheel and gate bearing with a length of 144 mm and a bending moment of 23,836.995 N-mm. The
flange coupling is designed to withstand the amount of shear stress caused by the shaft while preventing
obstruction on the 4th sprocket which gives an outer flange diameter of 80mm. Each of the dimensions of
the flange coupling are based on the shaft diameter of 25.4mm. The flange thickness is determined by
multiplying the shaft diameter by 0.5 which results to a value of 12.7mm. The diameter of the flange
coupling hub is determined by multiplying the shaft diameter by 2 which results to a value of 50.8mm
while its length is determined by multiplying the shaft diameter by 1.5 which results to a value of
38.1mm. The bolts attached to the flange couplings must withstand the amount of shear stress caused by
the shaft. The placement of the bolts must be in between the flange area which results to a diameter
65.4mm to prevent the flange from deforming while enough room is provided for the sprocket to operate.
Without interference with the sprocket, M6 bolts are used which has a diameter of 6mm. Followed by the
maximum shaft stress of 42 MPa, the maximum torque done by the shaft is 135.139N-m. The maximum
torque is used to determine the minimum number of bolts to be attached on the flange couplings. A
minimum of 4 bolts are required to attach a pair of flange couplings in this design which is safe to place a
number of 8 bolts to the couplings.
4.2.5 Design Calculation of Flywheel
The Flywheel connects to shaft B and aligns with the sprocket D4. In this design, the flywheel is
important which transmits force to the hacksaw through the connecting rod. The type of material in
flywheel use in this design is cast iron. Through the use of equation 3.46, the ideal mechanical advantage
is 0.742. The speed of flywheel is 9.88 rad/s by substituting the values IMA and the maximum speed of
sprocket D4 using the same equation. Using equation 3.45, the radius of the flywheel is determined
61
followed by the flywheel diameter which is determined by multiplying the radius by 2. To solve for the
radius of the flywheel, the mass of the flywheel should be determined using the equation 3.44 given by
the bending moment of shaft B at equation 3.32. Given by the permissible working stress of the shaft
according to Khurmi (2005) at 84 MPa, and the length of the shaft at 136 mm which is enough to mount a
flange coupling and a block bearing in order to compensate the weight of the flywheel, the bending
moment of the shaft is determined at 25,239.17 N-mm. Using the bending moment and the length of the
shaft, the mass of the flywheel is determined at a maximum value of 18.92 kg. The market availability of
the cast iron, the material used to fabricate the flywheel, has led to set the mass of the flywheel at 5 kg
with the material thickness of 10 mm. Using the given mass of the flywheel, the radius of the flywheel is
determined at 147.655 mm followed by the diameter of 295.31 mm.
4.2.6 Design Calculation of Connecting Rod
The connecting rod converts rotational motion to linear, oscillating motion during power
transmission. The connecting rod A is connected between the flywheel and the oscillating rod or
connecting rod B which then connects to the connecting rod C. The connecting rod C is connected to the
hacksaw in order to compensate its cutting motion during angular adjustments. Based on table 3.7, the
material used for the connecting rods is mild steel which has a permissible crushing stress of 320 MPa.
The motion of the connecting rod A follows the rotational motion of the flywheel from one side and the
linear motion of the connecting rod B on the other side. Based on the motion of the connecting rod A, the
buckling load with respect to the x and y axis shall be considered in order to maintain its stability during
operation. Its cross-sectional area is considered in order to minimize the chances of deformation which is
rectangular. Given by the width of the connecting rod A equal to the crank pin length of 16 mm, and the
length of the connecting rod A of 0.29 m, a trial and error is done using equation 3.51 to determine the
depth of the connecting rod such that the buckling load with respect to the x and y axis are equal. With the
buckling load at both axis equal to 144,810.94 N, the depth of the connecting rod A is determined at 32
mm. The motion of the connecting rod B is linear which lies on the x-axis. Because of its limited motion,
the cross-sectional area at the connecting rod B is determined as circular with its buckling load only on
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the x-axis. Given by its diameter of 22.5 mm and its length of 0.53 mm, the buckling load of the
connecting rod B is determined at 58, 265.285 N. In order to minimize the cost and time for fabrication,
the diameter of the connecting rod C is equal to the connecting rod B where the cross-sectional area of the
connecting rod C is circular. With its given length of 0.2 m, the buckling load of the connecting rod C is
108, 881.48 N.
Table 4.4 Connecting Rods Dimensions
Connecting Rod
Length
Width
Depth
Diameter
Wcrx
Wcry
A
0.29 m
0.016 m
0.032 m
-
144,810.94 N
144,810.94 N
B
0.53 m
-
-
0.0225 m
58,265.285 N
-
C
0.2 m
-
-
0.0225 m
108,881.47 N
-
4.2.7 Design Calculation of Crank Pin
The crank pin, which connects to the flywheel, allows the connecting rod to move along with the
direction of the flywheel at a certain point. The crank pin supports the connecting rod A and is welded at
the flywheel where the stress when operating the pedal powered hacksaw machine does not exceed the
yield stress of the cast iron in order to prevent the flywheel from deforming. Through the use of
solidworks which simulates the stress between the flywheel and the crank pin, the region at which the
stress is permissible is located at 105 mm from the center of the flywheel. This determines the distance
between the crankpin and the center of the flywheel. The diameter of the crank pin is determined using
equation 3.62 given by the maximum allowable bending stress of 80 MPa (Khurmi, 2005), the flywheel
torque of 67.11 N-m which is determined by dividing its transmitted power to the angular speed of the
flywheel, and the standard weld size of 6 mm based on the flywheel thickness of 10 mm at table 3.8. The
crank pin diameter is determined at 16 mm followed by its length equal to its diameter of 16 mm.
63
4.2.8 Design Calculation of Hacksaw
The Hacksaw serves as the output of the pedal power hacksaw. The forces that act on the hacksaw
are the cutting and the trust force. The cutting force is the horizontal component of the hacksaw which
associates with the stroke of the hacksaw blade. The tangential force of the flywheel serves as the basis to
determine the cutting force. By dividing the torque of 67.11 N-m transmitted by the flywheel over the
distance of the crankpin to the center of the flywheel which is 105 mm that would result to the force
exerted on the connecting rod A of 639.14 N. The force exerted on the connecting rod B is the horizontal
component of the force applied at 639.14 N with angles ranging from a minimum of 0 o and 21.23o
resulting at a force of 231.44 N. The force exerted on the connecting rod C is determined based on the
force exerted on the connecting rod B followed by its horizontal cutting angle position that ranges
between 0o to approximately 42o resulting at a force of 187.27 N. The cutting force is the horizontal
component of the force applied at the connecting rod C with its horizontal cutting angle position ranging
between 0o to approximately 42o that results to a force of 125.308 N. Based on the stroke length travelled
by the hacksaw, the availability of the hacksaw blade in the market is the 14 TPI power hacksaw blade
with a blade length of 350 mm. Using the relative velocity method, the velocity of the hacksaw is
determined based on the given angular velocity of the flywheel at 9.88 rad/s. The velocity of the hacksaw
is equal to the velocity of the connecting rods B and C which is 1.0374 m/s. The power output of the
pedal powered hacksaw machine is determined using eqn 3.64 given by the cutting force 125.308 N and
the velocity of 1.0374 m/s which is 134.53 W. Using the power input of 186.5 W and the power output of
134.53 W, the overall efficiency of the pedal powered hacksaw machine is 72.134%
4.3 Fabrication
The design consideration and dimension in Section 4.2 was followed during the fabrication of the
Pedal Powered Hacksaw machine. The pedal operated hacksaw machine conforms the design shown in
figure 4.2.
The pedal powered hacksaw machine construction follows:
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1. The design parameters were followed to construct the pedal powered hacksaw machine shown in
sections 4.2.2, 4.2.2.1, 4.2.2.2, 4.2.2.3, 4.2.2.4, 4.2.3, 4.2.4, 4.2.5, 4.2.6, 4.2.7, and 4.2.8.
2. Mild steel was used to fabricate the machine body design shown along with 6 caster wheels
mounted below the frame shown in the figure 4.5.
Figure 4.5 Image during fabrication
3. After the machine frame was fabricated, the sprockets and chains were installed and alignment
was performed on the chain drive based on calculated design shown in Section 4.2.2, 4.2.2.1,
4.2.2.2, 4.2.2.3, 4.2.2.4 and 4.2.3. The picture during the installment were shown Figure 4.6
Figure 4.6 Image during fabrication
65
4. After the chain drives were installed, the shaft was mounted and fitted on the two pillow block
bearings installed. Then the flywheel was welded at the left side of the shaft. This procedure was
based on the design conceptualization shown in Section 4.2.
Figure 4.7 Images during fabrication
5. After the flywheel system was installed, the connecting rod A was fabricated by the use of an
Angle Grinder and a Drill Press while the connecting rod B and C were fabricated using solid
mild steel material with the use of lathe and milling machine. After the connecting rods were
fabricated, they were attached to the machine based on its design concept shown in Section 4.2.6
and 4.2.7.
Figure 4.8 Images during fabrication
66
6. The hacksaw holder and hacksaw frame were next installed through attachment in connecting rod
C shown in Figure 4.9.
Figure 4.9 Image during fabrication
7. The vise was then mounted on the wooden platform installed below the hacksaw holder shown in
Figure 4.10.
Figure 4.10 Image during fabrication
8. The fabrication of the Pedal Hacksaw Machine was completed shown in Figure 4.11.
67
Figure 4.11 Image after fabrication
The reciprocating motion of the hacksaw occurs during pedaling where the user transmits power to the
flywheel that connects the hacksaw via connecting rods converting rotational motion to linear motion.
4.4 Testing and Data Gathering
The testing of the pedal operated hacksaw machine was done at the University of San Carlos –
Technological Center Machine Shop. The available materials and instruments were considered within the
area. Instruments and equipments need for testing are shown in table 4.5.
4.4.1 Experimental Set-up
The schematic diagram of the actual experimental set-up for this study was shown in figure 4.12. The
speed of the hacksaw was measured by the tachometer facing towards the flywheel shown in the figure
below. The hacksaw was held above the sample cutting material where it was locked through the bench
vise in which the sample material does not move during the cutting operation. Moreover, the actual
experimental setup for the electric powered hacksaw machine was also shown in figure 4.13
The measuring equipments used during the experiment include the timer that was used to record the
cutting time, the tachometer that was used to record the speed of the hacksaw and the vernier caliper that
68
was used to measure the depth of cut. The sample workpieces used for cutting include the engineering
plastic, wooden block, and the mild steel solid shaft. This experiment was done at the University of San
Carlos – Machine Shop.
Figure 4.12 Experimental Set-Up
Figure 4.13 Power Hacksaw Machine Set-Up
69
4.4.2 Testing Instruments and Equipment
In measuring the dimensions, speed, and corresponding time of cut of pedal operated hacksaw machine,
several instruments and equipment will be used in order to obtain the necessary data under Section 4.6.
Table 4.5 shows the instruments to be used during the testing and gathering of data of the pedal operated
hacksaw machine.
Table 4.5 Instruments and Equipment needed for the experiment
Instrument/Equipment
Description
Tachometer is an electronic used for measuring
the rotational speed of the flywheel during the
testing then calculate the linear speed to get the
cutting speed of hacksaw machine by the use of
equation 3.48.
Vernier Caliper is an instrument that will measure
the diameter, thickness and the acquired depth of
cut of the material.
70
Timer is an instrument used for measuring the
time during cutting operation.
4.4.3 Testing Procedure
During the testing operation, to determine the cutting speed, cutting time, number of stroke and depth
of cut, the pedal powered hacksaw machine was subjected to the cutting performance consists of three
material type.
 Tachometer Installation and Setting
1. The tachometer used in the setup could work either in contact or non-contact type of operation.
For this study, a non-contact mood was used to gather the data for the speed through its red laser
light.
2. The tachometer was initially in contact mood of operation. The roller was removed by loosening
the screw at the back portion of the tachometer until the screw was detached from its place. The
roller holder was removed by sliding outward. The laser housing was found after the roller holder
was removed. Before mounting the tachometer into the frame, the battery was checked if it is still
working.
3. The tachometer was then installed perpendicular at the face of the flywheel with a distance of 2
inches from the tip of the laser housing to the face of the flywheel as stated in the instruction’s
manual and the laser was positioned at the pin of the connecting rod.
4. The reflective tape was also placed on the face of the flywheel where the laser was pointed as this
would serve as the sensor of the tachometer.
71
5. The tachometer was actuated by long pressing the power button located at the head of the meter,
displaying its speed parameters. Before the experiment started, the unit of speed was set to rpm
according to the standard unit used in this study.
 Pedal Powered Hacksaw Machine Testing
6. Three different workpieces were used for cutting namely solid shaft mild steel, engineering
plastic and a wooded block. The dimensions of the workpiece were measured by the use of a
vernier caliper where its initial size/diameter was recorded before mounting into the bench vise.
7. The sample workpiece was mounted into the bench vise by loosening the lead screw of the vise.
The material to be cut was then secured on the vise by tightening the screw and also the jaw of
the vise to ensure that the workpiece was in place.
8. The rider/user were on the maneuver of the pedal and all the testing instruments and device were
activated getting ready for the testing.
9. The time started together with the pedaling operation at a time allotment of 3 minutes for every
workpiece for both pedal cutting and manual cutting operation.
10. After 3 minutes, the resulting cutting depth of the workpiece were then measured using the
vernier caliper tool. Moreover, the data obtained in force gauge, tachometer and the power meter
were also recorded.
11. The same time allotment was used for another workpiece sample. The workpiece to be cut was
secured in the bench vise to avoid unnecessary movement. Using the standard hacksaw for
cutting, the person does the cutting for 3 minutes. After 3 minutes, the cutting depth was then
recorded.
12. The same procedure was followed for other workpiece type of material. All the necessary data
such as cutting depth, cutting time, and cutting speed were recorded in Appendix A.
 Electric-Powered Hacksaw Machine Testing
13. The same procedure was followed in step 6 and 7 as to the materials to be tested and mounted to
the vise.
72
14. After the workpiece was secured and tightened on the bench vise, the switch was checked first to
ensure that it is in off mode before plugging in to the outlet for safety purposes.
15. The power cable was then plugged into the power outlet.
16. The push button switch was pressed and the machine begins to actuate. Since the electric powered
hacksaw frame was hydraulically operated, the hacksaw frame was slowly pushed down with its
blade towards the workpiece to enable cutting.
17. Same as the pedal powered hacksaw machine, the maximum cutting time allotment to cut the
workpiece for this machine is also 3 minutes and all the necessary data were recorded with the
same parameters as the pedal powered hacksaw machine.
4.4.4 Fabricating Machines and Equipment
In fabricating the pedal operated hacksaw machine, several machines and equipments were to be used.
These machine tools were commonly found in machine shops with various sizes depending upon the type
of application. Table 4.6 shows the list of equipment tools necessary during the fabrication of the pedal
operated hacksaw machine.
Table 4.6 Machines and Equipment for Fabrication
Machine/Equipment
Description
Welding Machine is a device that provides an
electric current to joint materials usually in metals
such as joining piece of carbon steel in hacksaw
frame and in fabricating the entire frame of the
machine.
73
Drill Press Machine is an equipment used
primarily for drilling holes or to enlarge a
cylindrical hole in a workpiece such as making
holes in the frame for various screws and making
slots in workpiece platform for bench vise sliding
slot.
Bench Grinder is a benchtop grinding machine
used for grinding, sharpening or shaping a cutting
tool and also used to making chamfers and fillets
such as in bench vise.
Lathe Machine is a machine tool used to rotate a
workpiece about an axis to perform various
operations such as facing, turning, drilling in
fabricating the spool and threading for customized
screws.
Circular Power Saw is a power tool with a circular
rotating disk blade that is pushed across the
workpiece to be cut and this is used to cut the
metal bars into desired length for the machine
frames.
74
Adjustable Wrench is a common hand tool used to
loosen or tighten a hex nut or bolt in place. It has a
jaw where the nut or bolt is fitted and adjusted.
Angle Grinder is a versatile tool used for grinding
down excess sharp edges or flattening the welded
area to provide smooth surface between the joints.
Bench Vise is a mechanical tool used to secure an
object or workpiece that is to be worked on.
Hydraulic Pipe Bender is a machine tool used to
bend various types of pipes such as steel pipes,
aluminum pipes and steel pipes. It is used to bend
pipe such as in hacksaw frame holder.
75
Philips Head Screwdriver is a hand tool with starshaped end used to drive a screw with the same
shaped head such as the screw found in mounting
the driving sprocket into the pedal crank.
The Vertical Milling Machine is a machine tool
which are used for machining solid shafts as
connecting rods for the pedal power hacksaw
machine. Its spindle is vertically oriented which is
good for drilling slots for the connecting rods.
76
CHAPTER V: RESULTS AND DISCUSSION
During testing, the data for each parameter was tested for 5 trials on each workpiece. Three
workpieces include a solid mild steel shaft, engineering plastic, and wood lumber. Appendix A shows the
following parameters that were recorded on the Pedal Powered Hacksaw which consist of cutting time,
cutting speed, and depth of cut, while the experimental data of an electric power hacksaw is shown on
Appendix B, in which parameters include the cutting time, cutting speed and depth of cut. To determine the
data for each parameter in the pedal powered hacksaw machine, testing instruments and equipment were
utilized as shown in table 4.5, to record the values through the use of the following procedures shown in
4.4.3. The parameters of getting the value of cutting time, cutting speed and depth of cut in electric power
hacksaw were recorded through the use of a timer, and a vernier caliper. The output speed is determined
as the cutting speed calculated through equation 3.64 using the tachometer reading and the given crank
diameter. After 5 trials of testing, the average parameters were determined for both the pedal powered
hacksaw and the electric powered hacksaw per sample material given. The average cutting depth of each
workpiece was divided by the average cutting time of each workpiece for both equipment, which
determines the ratio of performance during cutting. The cutting time and the cutting performance were
interpreted through a bar graph which compares the data gathered by the electric powered hacksaw and
the pedal powered hacksaw per given sample workpiece.
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Average Cutting time
200
180
160
Cutting time, sec
140
120
100
Electric Hacksaw
80
Pedal Hacksaw
60
40
20
0
Mild Steel
Engineering Plastic
Wood Lumber
Sample Material
Graph 4.1 Average Cutting Time
The electric powered hacksaw can completely cut a 25.4 mm dia. mild steel at an average of 117.2
seconds with a cutting speed of 60 spm while the pedal powered hacksaw can cut a 25.4 mm dia. mild steel
with a cutting depth of 10.8 mm within a time limit of 3 mins or 180 seconds and a cutting speed of 48 spm.
For a 25.4 mm dia. engineering plastic, the electric powered hacksaw can completely cut the workpiece at
6.08 seconds with a cutting speed of 60 spm while the pedal powered hacksaw can fully cut the
workpiece at 10.704 seconds with a cutting speed of 57 spm. And for a 41 x 41 mm wood lumber, the
electric powered hacksaw can completely cut the workpiece at 8.19 seconds with a cutting speed of 60
spm while the pedal powered hacksaw can fully cut the workpiece at 28.32 seconds with a cutting speed
of 54 spm. Based on the graph above, the cutting time of the pedal powered hacksaw is greater than the
electric powered hacksaw by 34% on the mild steel, 43% on the engineering plastic and 71% on the wood
lumber.
78
Average Cutting Performance
6
Cutting Depth/ Cutting Time
5
4
3
Electric Hacksaw
Pedal Hacksaw
2
1
0
MildSteel
Plastic
Wood
Sample Material
Graph 4.2 Average Cutting Performance
Using a mild steel sample, the average cutting performance of the electric powered hacksaw was
determined at 0.2167 mm/s while the average cutting performance of the pedal powered hacksaw was
determined at 0.06 mm/s. Using an engineering plastic workpiece, the average cutting performance of the
electric powered hacksaw was determined at 4.178 mm/s while the average cutting performance of the
pedal powered hacksaw was determined at 2.37 mm/s. Using a wood lumber workpiece, the average cutting
performance of the electric powered hacksaw was determined at 5 mm/s while the average cutting
performance of the pedal powered hacksaw was determined at 1.448 mm/s. Based on the graph above, the
cutting performance of the electric powered hacksaw is greater than the pedal powered hacksaw by 71%
on both the mild steel and the wood lumber while 43% on the engineering plastic.
79
CHAPTER VI: CONCLUSION AND RECOMMENDATION
6.1 Conclusion
The researchers successfully designed the pedal powered hacksaw machine in section 4.2,
and was fabricated in section 4.3. The pedal powered hacksaw machine was successfully tested in a
workplace without the access of electricity by determining its cutting speed, cutting time and depth of cut
of the three sample workpieces with its performance and productivity compared to the electric powered
hacksaw machine. Based on the data provided, we determined that the pedal powered hacksaw can cut at a
lesser time than the electric powered hacksaw by 34% on the mild steel shaft, 43% on the engineering
plastic and 71% on the wood lumber with a lesser cutting performance compared to the electric powered
hacksaw by 71% on both the mild steel and wooden lumber and 41% on the engineering plastic sample
workpiece. With its greater cutting performance, the electric powered hacksaw still consumes electricity
where greater power was added compared to the pedal powered hacksaw. This adds to the operation cost
done by the electric powered hacksaw during cutting. The pedal powered hacksaw is comfortable in terms
of operation during testing according to the user. The experiment and the data provided conclude that the
pedal powered hacksaw can be operated at a lesser operating cost due to its alternative access to power.
6.2 Recommendation
 Be accurate in measurements especially in fabrication to avoid error and misalignment during the
fitting stage.

Always use proper tools for accuracy such as L-square for maintaining the right angle especially
in fabricating the frame, circular bandsaw to ensure straight cutting geometry.

Ensure proper alignment of sprockets to avoid chain alignment.

Ensure the connecting rods does not make any error or does not make any play with the outer
housing pipe especially in oscillating rod during the operation to avoid vibration.

It is important to choose chain drives and sprockets to avoid slippery during operation and
alignment and the sized to create drive ratios which enable the operator to maintain the desired
pedaling speed usually about minimum 200 rpm.

The seat should be adjusted to permit full extension of the legs during pedaling.
80

Be observant of the machine behavior during the testing process if there is a need to
provide a bracket or braces on some parts of the frame to add strength and stability.
Bill of materials
Below were the materials specification needed for fabrication of pedal operated hacksaw machine.
The quantity and the corresponding estimated prices were shown based upon the recent market pricing.
Table 4.7 Bill of Materials
Materials
Quantity
Price
Total Cost
Prototypes
1” x 0.75” OD Pipe
5 kgs
Php 50/kg
Php 250
35 x 35 cm Angle Bar + 1” x 1” x
0.065” Square Tube
Caster Wheel
6 kgs
Php 35/kg
Php 210
6
Php 318
Php 1908
ECLIPSE 1” x 14" x 10T
Hacksaw Blade
2
Php 406
Php 812
Pedal
1
Php 120
Php 120
Saddle
Hub
C-Wheel
H-Chip
1
1
1
1
Php 195
Php 120
Php 395
Php 75
Php 195
Php 120
Php 395
Php 75
Coff.- Angle
1
Php 145
Php 145
H-Bar ofs
1
Php 250
Php 250
H-post ryder
1
Php 495
Php 495
Pillow Bearing
1
Php 320
Php 320
12 mm bolt
1
Php 12
Php 12
Washer
1
Php 3.00
Php 3.00
12 mm nut
1
Php 3.00
Php 3.00
10 mm x 80 mm Flange
1
Php 85
Php 85
1” mild steel shaft
1
Php 140
Php 140
8 mm x 300 mm flywheel
1
Php 580
Php 580
1” x 1” square tube
1
2” x 1” rectangular tube
1
Php 2,480
Php 2,480
81
2” x 4” rectangular tube
1
Angle Bar
1
Php 750
Php 750
Speed Sprocket
2
Php 280
Php 560
CHAM
1
Php 150
Php 150
Steel Ordinary Tube
2.6 m
Php 45/m
Php 117
Rear Derailleur
1
Php 150
Php 150
M5 X 30 mm bolt
5
Php 1.50
Php 7.50
M5 x 50 mm bolt
5
Php 2.00
Php 10
M5 Washer
10
Php 1.00
Php 10
M5 Nut
10
Php 1.00
Php 10
8 mm x 25 mm allen cap screw
4
Php 24.00
Php 96
8 mm hex nut screw
4
Php 1.00
Php 4.00
5/16 flat washer
4
Php 1.50
Php 6.00
8 mm x 25 mm S/S A/S
5
Php 18
Php 90
350 x 30 x 8 mm Mild Steel Plate
2
Php 115
Php 230
230 x 30 x 8 mm Mild Steel Plate
1
Php 85
Php 85
200 x 160 x 5 mm Mild Steel
Plate
2
Php 115
Php 230
200 x 40 x 5 mm Mild Steel Plate
1
Php 85
Php 85
60 x 40 x 5 mm Mild Steel Plate
2
Php 85
Php 170
5/8" x 45 mm CRS
1
Php 35
Php 35
1" dia x 6" B.I Pipe Schd. 40
1
Php 70
Php 70
6202 KOYO Bearing
2
Php 160
Php 320
12 x 40 mm CS
5
Php 10
Php 50
12 mm HW
5
Php 3.00
Php 15
1/2 FW
5
Php 3.00
Php 15
long nut
2
Php 70
Php 140
H.T
2
Php 9.00
Php 18
1 gal Boysen QOE black enamel
paint
1'' dia x 29" shaft
1
Php 432
Php 432
1
Php 340
Php 340
82
1 3/4" dia x 6/2" shaft
1
Php 275
Php 275
3/8" x 1" Set Screw
2
Php 19
Php 38
Miscellaneous
A3 CAD Print
1
Php 100
Php 100
Grinding Disc
1
Php 45
Php 45
Cutting Disc
2
Php 60
Php 120
2/2” Globe paint brush
2
Php 18
Php 36
Total Cost
Php 13,952
83
Gantt chart
Figure 5 Gantt Chart
84
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89
APPENDIX A: PEDAL POWERED HACKSAW MACHINE EXPERIMENTAL DATA
Date: October 8, 2021
Diameter: 25.4 mm
Material: Solid Mild Steel Shaft
User’s Body Specifications:
Height = 164 cm
Heart Rate = 64 bpm
Weight = 56 kg
Body Mass Index (BMI) = 20.8
Trial
Cutting Speed
Cutting Time
Cutting Depth
1
44 spm
180 s
10 mm
2
48 spm
180 s
11 mm
3
49 spm
180 s
11 mm
4
46 spm
180 s
10 mm
5
52 spm
180 s
12 mm
Ave
48 spm
180 s
10.8 mm
Date: October 8, 2021
Diameter: 25.4 mm
Material: Engineering Plastic
Trial
Strokes per min
Cutting Time
Cutting Depth
1
60 spm
9.56 s
25.4 mm
2
58 spm
10.26 s
25.4 mm
3
59 spm
10.58 s
25.4 mm
4
52 spm
12.04 s
25.4 mm
5
57 spm
11.08 s
25.4 mm
90
57 spm
Ave
10.704 s
Date: October 8, 2021
25.4 mm
Size: 41mm x 41mm
Material: Wood Lumber
Trial
Strokes per min
Cutting Time (s)
Cutting Depth (mm)
1
54 spm
28.34 s
41 mm
2
57 spm
26.2 s
41 mm
3
53 spm
28.41 s
41 mm
4
52 spm
30.02 s
41 mm
5
53 spm
28.63 s
41 mm
Ave
54 spm
28.32 s
41 mm
APPENDIX B: ELECTRIC POWERED HACKSAW EXPERIMENTAL DATA
Date: October 7, 2021
Diameter: 25.4 mm
91
Material: Solid Mild Steel Shaft
Electric Power Hacksaw Motor Specifications:
Output Power = 1/3 HP
Current = 3 Amps
Pole = 4
Voltage = 220 V
RPM = 1720
Heat = 600C
Trial
Cutting Speed
Cutting Time (s)
Cutting Depth (mm)
1
60 spm
116 s
25.4 mm
2
60 spm
118 s
25.4 mm
3
60 spm
118 s
25.4 mm
4
60 spm
118 s
25.4 mm
5
60 spm
116 s
25.4 mm
Ave
60 spm
117.2 s
25.4 mm
Date: October 7, 2021
Diameter: 25.4 mm
Material: Engineering Plastic
Trial
Cutting Speed
Cutting Time (s)
Cutting Depth
1
60 spm
6.56 s
25.4 mm
2
60 spm
5.92 s
25.4 mm
3
60 spm
6.33 s
25.4 mm
4
60 spm
6.18 s
25.4 mm
5
60 spm
5.43 s
25.4 mm
Ave
60 spm
6.08 s
25.4 mm
Date: October 7, 2021
Size: 41mm x 41mm
92
Material: Wood Lumber
Trial
Cutting Speed
Cutting Time (s)
Cutting Depth (mm)
1
60 spm
8.14 s
41 mm
2
60 spm
8.32 s
41 mm
3
60 spm
8.16 s
41 mm
4
60 spm
8.28 s
41 mm
5
60 spm
8.08 s
41 mm
Ave
60 spm
8.19 s
41 mm
APPENDIX C: USERS’S MANUAL GUIDE FOR PEDAL-POWERED HACKSAW
MACHINE OPERATION
 Safety Measures of the Machine
Before operating this machine, it is necessary to read and know the basic safety reminder and
be able to practice safety precautions when handling and operating to prevent serious damage to the
machine as well as the user. Below are the listed do's and don't when using the pedal-powered
hacksaw machine:
1. Always check the chain especially the links as it may loosen for long period of time of using the
machine. Most especially when cutting mild steel materials as it requires higher force to cut thus
check the pins of the chain to ensure that the chain is in good condition.
93
2. Do not operate the machine in an inclined and uneven floor surface as this can affect the stability of
the machine and comfortability of the user during the operation.
3. Lubricate the chain regularly also the block bearing carrying the shaft as this are the main
transmission of the machine and should not be experiencing any rust. Never operate the machine
directly when these parts are not lubricated.
4. Before operating the machine, be sure to lock all the six caster wheels of the machine to prevent it
from moving while pedalling.
5. Do not store this machine in a dusty and moist environment.
6. Before seating into the saddle of this machine, adjust the height of the seat and its distance from the
handlebar according to your comfortability to prevent backpain and other serious injury as this
machine is also designed ergonomically.
7. Check all the bolts and nuts of the machine to ensure that they are in place and are tight to avoid
convenience during the operation and to prevent damage to the machine.
8. Before mounting the workpiece into the vise, inspect the hacksaw blade if it is tightly installed in
its hacksaw frame this is to prevent breakage of the blade when not properly tightened most
especially when cutting hard materials such as mild steel.
9. When mounting the workpiece into the machine vise, be sure to make it tight and secured to prevent
the workpiece from moving during the cutting process as this could also leads to breakage of the
blade when the workpiece is not properly secured in the bench vise.
10. Do not wear baggy pants when operating this machine as the driving sprocket may caught your
pants while pedalling. It is advisable to wear shorts and shoes when operating this machine.
 Machine Maintenance and Troubleshooting
One of the reasons that prolong the life span of the machine is by regularly maintaining its
components and monitoring its condition to ensure and maintain the performance of the machine even
for how many years of operation. Below are the essential components of the machine with its
procedure when replacing/troubleshoot that necessarily have to undergo regular maintenance:
1. Pedal Bottom Bracket/Crank Set
1.1 Pedal
1) When maintaining or replacing a pedal, a 10 mm open end wrench or adjustable
wrench and a grease are the things needed for this maintenance.
2) Using the 10 mm open end wrench, carefully rotate the threaded bar of the pedal
counterclockwise until the pedal is totally removed from the crank.
94
3) In case the threaded bar of the pedal is hard to rotate or remove due to in contact
rust between the pedal and the crank, use an engine oil or WD-40 to lubricate the
pedal.
4) When replacing a new pedal, before installing a new pedal into the crank
carefully put some grease into its threaded bar of the pedal to protect the threaded
metal of the pedal for rust.
5) Using again the 10 mm open wrench, carefully rotate the threaded bar of the
pedal in a clockwise rotation until the pedal is tightened and fully secured into the
crank.
1.2 Bottom Bracket/Crank
1) When maintaining or replacing a bottom bracket/crankset, a 10 mm socket ratchet
wrench and a grease are the things needed for this maintenance.
2) Using the 10 mm socket ratchet wrench, remove the hex nut inside the crank
housing by rotating counterclockwise while holding the crank in a way that itdoes
not rotate together with the nut until the nut is removed. The same thing for the
other side of the bottom bracket.
3) After the hex nut (both sides) are removed, remove the threaded lock of the
bottom bracket by rotating counterclockwise using a hand the same way on the
other side of the bracket.
4) Once both threaded locks are removed, the crankshaft can now be dismantled
from the bottom bracket of the frame.
5) When replacing a new bottom bracket crankset unit, the same procedure to be
followed however before installing the new crankset, it is advisable to put grease
into the crankshaft especially the ball bearings present inside the bottom bracket
as they are responsible for the smooth rotation of the crank and they must be
lubricated with grease.
6) Return the hex nut once the crankset is fully secured and installed. Do not over
tighten the nuts as it may cause loss thread and cannot be tightened anymore.
2. Chain Drive
1) This is the most essential part of the machine as this serves as the transmission of
human pedaling into a useful cutting operation. Thus, regular maintenance is
required for this part of the machine. Lubrication is the basic maintenance for
chain drive since chains consist of linkages that involves movement and tension
of forces.
2) When maintaining the chain drives of this machine aside from lubrication, proper
alignment and sag adjustment is also important. Check the alignment of the
sprocket first by carefully watching at the end of the sprocket if the chain path is
linear.
3) Try to rotate the pedal crank by hand if the chain goes out from one of the
sprockets or misaligned. If so, proceed to the next step.
95
4) Check the condition of the sprockets if one of them is loose that would contribute
to the misalignment of the chain. Remove the chain first to diagnose the sprocket.
Hold the sprocket and carefully give a force side to side if there is a play happen. If
so, tighten the faceplate nut of the sprocket using an adjustable wrench. Do not
over tighten the nut as it may also difficult for the sprocket to rotate.
5) Once the play is eliminated in the sprocket/s, mount the chain back to the
sprockets and rotate the pedal crank if the chain still goes out from the sprocket
tooth. If the problem does not eliminate, proceed to the next step.
6) Evaluate the sag of the chain if it is too loose. If so, adjust the chain tensioner in
such a way that the sag decreases. Same procedure for the second chain drive to
be followed.
7) When replacing a new chain, carefully remove the chain using a chain cutter and
install the new one. Make sure that the same specification for the new chain as to
the old one.
3. Shaft
1) When replacing this component, be sure that the replacement must be of the same
diameter and length from the original one.
2) To completely remove the shaft, the flywheel must be removed first by loosening
the set screws found at the hub of the flywheel. Using an allen wrench, carefully
drive the set screw in counterclockwise motion until all the set screws are
removed.
3) Slide the flywheel outward to remove it from the shaft.
4) Remove the shaft from the block bearing. This will be done by detaching two
block bearings from the machine frame. Using the 12 mm open- end wrench or
can be adjustable wrench, loosen the 12 mm nut that attaches the two block
bearings from the frame of the machine.
5) Once the block bearings are detached from the frame, loosen the set screwsfound at
the housing using an allen wrench.
6) Slowly slide the shaft away from the block bearings until the shaft is fullyremoved
from the block bearings.
4. Pillow Block Bearings
1) The block bearings in this machine are automatic self-aligned with the shaft.
Which means that the shaft housing automatically adjust according to the
inclination placement of the shaft.
2) When maintaining the block bearing, an engine oil as a lubricant for the bearing
inorder to maintain a smooth performance with the shaft. To do that, remove the
plastic cover of the oil inlet of the block bearing and pour slowly the oil. Be
careful not to overflow the oil outside of the bearing.
3) To mount the block bearings into the machine frame, a 12 mm hex screws with
nuts are used. Using the adjustable wrench, tighten the nuts to prevent the block
96
bearing from moving from its place during the operation.
5. Hacksaw Blade
1) When installing or replacing the blade of this machine, be sure that the same
size and TPI of the blade replacement as the original one.
2) Remove the old blade from the hacksaw frame by loosening the lock screw
found at the rear of the hacksaw frame. This lock screw serves as the tension
adjuster of the blade.
3) Once the old blade was removed, mount the new blade into its mounting pins of
the hacksaw frame and tighten the lock screw by turning clockwise using the
adjustable wrench until the blade elongates and cannot be bend.
6. Caster Wheels
1) When replacing the caster wheels in this machine, a Philips head screwdriver is
the only thing needed for this maintenance.
2) Slowly flip the entire machine frame in such a way that the bottom frame is
facing towards you for easy access on the installation of the caster wheels.
3) Remove the old/destroyed caster wheel by loosening the screws around the
caster wheel that is turning the screws counterclockwise using the screwdriver.
4) Install the new replacement caster wheel into the bottom of the frame. Be sure to
tighten all the screws of the wheel to avoid serious physical injuryto the user.
97
APPENDIX D: PEDAL OPERATED HACKSAW CALCULATIONS
Sprocket Design Calculations
For Sprocket A:
Given Assumptions:
Pedalling Speed, N1 = 70 rpm
Design Power = Transmitted Power x Ks
Service Factor (Ks):
Load Factor, K1 = 1 (Constant Load)
Lubrication Factor, K2 = 1 (for drop lubrication)
Rating Factor, K3 = 1 (for 8 hrs per day)
From table 3.2:
ISO Chain No. = 08B
Pitch = 12.70 mm
Maximum Roller Diameter = 8.51 mm
Width between inner plates = 7.75 mm
Transverse Pitch = 13.92 mm
Minimum Breaking Load = 17.8 kN
From table 3.3:
Power rating of a 08B bicycle chain = 0.64 kW
Speed of the smaller sprocket or pinion, N2 = 100 rpm
98
From table 3.1:
Chain Type: Roller Chain
Therefore; T2 = 27 teeth
Pitch Diameter, D1:
Tooth Flank Radius, re:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Roller Seating Angle, α:
No. of teeth = 39
Roller seating radius, ri:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
99
Tooth height above the pitch polygon, ha:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
No. of teeth = 39
Top Diameter, Da:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Diameter = 157.83 mm
Root Diameter, Df:
Diameter = 157.83 mm
Roller seating radius = 4.4384 mm
For Sprocket B:
Pitch Diameter, D2:
100
Pitch Line Velocity, V2:
Tooth Flank Radius, re:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Roller Seating Angle, α:
No. of teeth = 27
Roller seating radius, ri:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Tooth height above the pitch polygon, ha:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
No. of teeth = 27
101
Top Diameter, Da:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Diameter = 109.395 mm
Root Diameter, Df:
Diameter = 109.395 mm
Roller seating radius = 4.4384 mm
For Sprocket C:
Pitch Diameter, D3:
No. of Teeth, T3:
Speed, N3:
Tooth Flank Radius, re:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
102
Roller Seating Angle, α:
No. of teeth = 27
Roller seating radius, ri:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Tooth height above the pitch polygon, ha:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
No. of teeth = 27
Top Diameter, Da:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Diameter = 109.395 mm
Root Diameter, Df:
Diameter = 109.395 mm
103
Roller seating radius = 4.4384 mm
For Sprocket D:
Speed, N4:
No. of teeth, T4:
Pitch Diameter, D4:
Pitch Line Velocity, V4:
Tooth Flank Radius, re:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
104
Roller Seating Angle, α:
No. of teeth = 20
Roller seating radius, ri:
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Tooth height above the pitch polygon, ha:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
No. of teeth = 20
Top Diameter, Da:
Pitch of 08B chain (Table 3.2) = 12.7 mm
Max roller diameter of 08B chain (Table 3.2) = 8.51 mm
Diameter = 81.184 mm
Root Diameter, Df:
Diameter = 81.184 mm
Roller seating radius = 4.4384 mm
105
Chain Drives Design Calculations
For Chain Drive A:
Chain Load, W:
Breaking Strength, WB:
Factor of Safety:
Minimum Center Distance, X1:
Number of Chain Links, KA:
106
Length of Chain, LA:
For Chain Drive B:
Chain Load, W:
From Table 3.3 (Khurmi, 2005):
Power rating of a 08B bicycle chain = 1.18 kW
Speed of the smaller sprocket, N4 = 200 rpm
Breaking Strength, WB:
Factor of Safety:
Minimum Center Distance, X1:
Number of Chain Links, KB:
107
Length of Chain, LB:
Shaft Design Calculations
At shaft A:
Tangential force acting on sprocket 2:
where: Pitch Line Velocity,
V = 0.573 m/s
Torque acting on sprocket 2,
Solving for Shaft Diameter:
where standard shear stress of shafts w/ keyway allowance,
108
Since available bore diameter for a 109.395 mm sprocket is 34 mm, it is safe to
assume that the shaft diameter is 34 mm.
At shaft B:
Tangential force acting on sprocket 4:
where: Pitch Line Velocity,
V4 = 0.850 m/s
Torque acting on sprocket 4,
Solving for Shaft Diameter:
where standard shear stress of shafts w/ keyway allowance,
109
Since available bore diameter for an 81.84 mm sprocket is 1 in, suggested shaft
diameter is 25.4 mm or 1 inch.
Shaft B is divided into two parts separated by a flange coupling. The length of the shaft b1
is 136 mm while the length of shaft b2 is 144 mm.
Solving for the bending moment of shaft B, Mw :
Where;
Solving for the bending moment at shaft B1, Mw1:
110
Solving for the bending moment at shaft B2, Mw2:
Solving for the flange coupling:
Flange outer diameter, Dco = 80 mm
Bore/ shaft diameter, ds = 25.4 mm
Flange thickness, tf :
Hub diameter, dh :
111
Hub length, lh :
Flange bolt circle diameter, Dcb :
Bolts:
Bolt diameter, db = 6 mm = 0.006 m
Shearing Stress of Shaft (Khurmi, 2005), Ss ≤ 42 MPa
Maximum shaft torque, T:
Number of bolts, n:
Since the minimum number of bolts attached to the flange coupling is 4, it is safe to
assume that the number of bolts attached is 8 bolts
112
Flywheel Design Calculations
Ideal Mechanical Advantage:
Flywheel Speed, ωf:
Mass of flywheel, mf:
Bending moment of shaft B1, Mw1 = 25,239.17 N-mm
Length of shaft B, yb = 136 mm
Let point A as reference point:
113
Converting to mass:
Since the maximum required mass of the flywheel is 18.92 kg, it is safe to assume that
the mass of the flywheel is set to 5 kg due to market availability
Flywheel Diameter, Df:
mf = 5 kg
density of cast iron, ρ = 7300 kg/m3
Flywheel thickness, tf = 10 mm = 0.01 m
Pitch line velocity of flywheel, Vf:
Speed of flywheel, ωf = 9.88 rad/s
Flywheel diameter, Df = 0.29531 m
Centrifugal Force, Fc:
114
Transmitted Power, Pf:
Torque of flywheel, Tf:
Crank Pin Design Calculations
Pin diameter, dp:
Let distance between the welded pin and the center of the flywheel, Dx = 105 mm
From table 3.8: S = 6 mm @ t = 10 mm
σb ≤ 80 MPa (max)
115
Let M = Tf ≤ 67.11 N-m
Length of pin, lp:
dp = 16 mm
lp = dp = 16 mm
Connecting Rod Calculations
For connecting rod A:
Radius of gyration about x-axis, Kxx:
width, bA = 0.016 m
depth, hA = 0.032 m
length, lA = 0.29 m
Cross-sectional Area, AA = bh = (0.016 m) (0.032m) = 0.000512 m2
116
where:
Buckling Load about x-axis, Wcrx:
Compressive yield stress of Mild Steel, σc ≤ 320 MPa
where:
Radius of gyration about y-axis, Kyy:
width, bA = 0.016 m
depth, hA = 0.032 m
length, lA = 0.29 m
Cross-sectional Area, AA = bh = (0.016 m) (0.032m) = 0.000512 m2
117
where:
Buckling Load about y-axis, Wcry:
Compressive yield stress of Mild Steel, σc ≤ 320 MPa
where:
For connecting rod B:
118
Radius of gyration, Kxx:
diameter, dB = 0.0225 m
length, lB = 0.53 m
Cross-sectional Area, AB:
where:
Buckling Load, Wcr:
Compressive yield stress of Mild Steel, σc ≤ 320 MPa
119
where:
For connecting rod C:
Radius of gyration, Kx:
diameter, dC = dB = 0.0225 m
length, lC = 0.2 m
Cross-sectional Area, AB:
where:
120
Buckling Load, Wcr:
Compressive yield stress of Mild Steel, σc ≤ 320 MPa
where:
Bicycle Frame Design Calculations
DIMENSIONS:
121
AE = 26.5”
CD = 7.31”
AB = 15.5”
CF = 14.0”
BC = 9.0”
DG = 6.04”
BD = 9.0”
EF = 36.0”
CALCULATIONS:
Let: Average Weight of Human = 165 lb
W1 = 130 lb
W2 = 35 lb

Solving for the reaction forces R1 and R2
Taking the moment at point E:
Moment @E:
(W2 x L2) + (W1 x L1) = (R2 x L3)
(35 lb x 27.18”) + (130 lb x 34.01”) = (R2 x 36.0”)
R2 = 149.24 lbf
Solving for R1:
R1 + R2 = W1 + W2
R1 + 149.24 lb = 130 lb + 35 lb
R1 = 15.76 lbf

JOINT E:
Solving for horizontal and vertical forces (Fx and Fy):
Fy = 0
Fx = 0
0
15.76 lb + EA sin 66.05 = 0
-17.24 cos 66.050 + EG = 0
EA = -17.24 lb (Compressive)
EG = 6.99 lb (Tensile)
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
JOINT A:
Solving for vertical force (Fy):
Fy = 0
17.24 sin 66.050 – AB sin 66.050 = 0
AB = 17.24 lb (Tensile)

JOINT B:
Solving for vertical force (Fy):
Fy = 0
17.24 sin 480 – BD sin 480 = 0
BD = 17.24 lb (Tensile)

JOINT D:
Solving for vertical force (Fy):
123
Fy = 0
-35 lb + 17.24 sin 480 + DC sin 66.050 = 0
DC = 24.28 lb (Tensile)
A. Seat Post Design Calculations
Diameter, dsp :
Permissible Yield Strength of Steel, σ ≈ 250 MPa
Bending Moment, Msp = 21.865 N-m
Length, ysp = 261.134 mm
Hacksaw Calculations
Force on the flywheel, Ff:
Tf = 67.11 N-m
Dx = 105 mm = 0.105 mm
124
Force on connecting rod A, FA:
Force on connecting rod B, FB:
Based on the movement of connecting rod A:
Minimum angle, ϕ1 = 0⁰
Maximum angle, ϕ2 = 21.23⁰
125
Force on connecting rod C, FC:
Minimum angle, θ1 = 0⁰
Maximum angle, θ2 = 42⁰
Force on Hacksaw, Fh:
126
Velocity of Hacksaw:
Dx = 105 mm = 0.15 m
ωf = 9.88 rad/s
Scale: 1 m/s = 100 mm
127
Since VB , VC , Vh lies in the same direction:
Efficiency Calculations
Pin = 186.5 W
128