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Design and Development of a Motorized Double Hacksaw Machine
Musilim, A.A.1, Ilegbusi, A.O.2, Orintunsi, T.K.2, Kolo, J.G.2 and Ogunbunmi, O.M.1
1. Welding & Fabrication Engineering Department, Yaba College of Technology, Nigeria
2. Mechanical Engineering Department, Yaba College of Technology, Nigeria
Corresponding author: abbeymuz@yahoo.co.uk, +2348038039793.
Abstract
The work aims at designing and fabricating a motorized double hacksaw machine, capable of
cutting two metal bars into various sizes and lengths using two hacksaws simultaneously at the
same time in order to achieve high-speed cutting rate and mass production of cutting operations.
The goal of this work is to reduce material cutting efforts and time, to be exposed to practical
metal work, test for the cutting strength of the machine and to undertake work that requires speed
and accuracy. Innovation and technology now play an important role in the global economy and
in everyday industrial applications hence the need for new ways of cutting. The scotch yoke
mechanism is used in the motorized hacksaw machine movement and it is arranged alongside
with hacksaws. In scotch yoke mechanism rotary motion is converted into a to and fro
(reciprocating) motion. The results for comparative times using developed motorized double
hacksaw machine and conventional hacksaw cuttings were also presented. It was evident that
motorized hacksaw machine gave better efficiency cutting than the conventional cutting.
KEYWORDS: High-speed, cutting rate, hacksaw, scotch yoke mechanism, efficiency
1. INTRODUCTION

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There are many industrial applications where the demands of hacksaw blade are
considerably increasing day by day with the growth of industrialization, engineering sectors, real
estate, and automobile sector and so on. The motorized hacksaw cutting machine is basically a
cutting device, which is used in almost every sector for cutting of materials like the angle iron,
channels, flat plates, rods and plastic pipes in two directions at the same time. There are various
hacksaws of different brands and sizes, with different specifications in the fabrication workshop.
These hacksaws are specifically designed to cut different materials such as metals bars, plastic,
wood and steel and so on in a short time. Whereas, metal needs to be cut at rapid rate for
fabrication industries to achieve mass production, as a result, the conventional handheld single-
frame hacksaw is unreliable to achieve this purpose requiring advances in technology. Two metal
bars can be cut simultaneously by using this motorized double hacksaw machine resulting in
high, accurate cutting speed and mass production for its users. Due to its simple operation, the
motorized double hacksaw machine eliminates all the limitations and disadvantages of a
conventional handheld hacksaw.
There is vast literature study to understand the concept which affect the performance of
the machine, and the concept of the two-way hacksaw cutting machine mainly carried out for
production base industries. There are many industrial applications where round bars or square
bars are required to be operated on different machines to make machine components such as
Shafts, Bolts, and Screws etc. These require a greater number of pieces to be cut for mass
production of these components, hacksaw cutting machine is basically deployed as a cutting
device. (Wilson, 1986). It is realized that regular power hacksaw machine can be supplanted with
robotized control hacksaw machine. (Chaudhary, 1986).
Designers of machines or structures must achieve acceptable levels of performance and at
the same time assures the part is safe and durable. Therefore, it is necessary to avoid excess
deformation such as bending, twisting or stretching of the machine’s components. In addition,
cracking in components must be avoided entirely to prevent the crack from progressing to the
point of complete fracture. To avoid structural failures the stress in a component must not exceed
the strength of the material, where the strength is simply the stress that causes a deformation or
fracture failure. Failures in mechanical structures occurs due to various reasons such as excessive
plastic deformation as a result of static overload or impact, instability, creep, stress corrosion
fatigue and brittle fracture. (Venturini, 2011). The material choice and testing of hacksaws sharp

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edge in light of mechanical properties, expressed that a suitable saw edge must be chosen for
better activity and fine cutting by choosing number of teeth per inch. (Bahaley, 2012).
Studies show that failures could occur due to mechanisms and environmental factors.
Furthermore, suggestions that failure analysis of a metal structure requires identifying the type of
failure mode. The failure mode is classified as either a deformation or fracture. (Boyer, 1975).
Conclusions were made that the process of identifying a failure mode is complicated, because
different techniques can be used to determine the actual cause of failure. The failures (operator
error, wrong amount of maintenance and physical wear and tear) analysis is a technical
procedure to investigate the root cause of failure of a product, components, equipment or an
unintentional mistake in designing, manufacturing or any unseen problem in a continuous
process. (Layer, 2002).
Sawing Machine
The sawing machine is a machine tool, designed to cut materials to a desired length or
contour. It functions by drawing a blade containing cutting teeth through the work piece. The
saw machine is faster and easier than hand sawing and is used principally to produce an accurate
square or mitered cut on the work piece.
The power hacksaw and the band saw are two common types of sawing machines, used
to cut metals in the machine shop. The power hacksaw uses a reciprocating (back and forth)
cutting action similar to the one used in a hand saw. The power hacksaw is used for square or
angle cutting of stock. The band saw uses a continuous band blade and a drive wheel, an idler
wheel support and then drives the blade.
i. Power Hacksaw Machine
The power hacksaw machine provides a vise for clamping the work and means for
reciprocating a U-shaped frame on which is mounted a straight steel hacksaw blade that cuts
when moving in one direction only. The saw presses down on the work during the cutting stroke
but is raised clear of the work during the return stroke. The basic forward and backward
movement of the cutting edge made the hacksaw one of the principal kinds of sawing machines
intended for control. The straightforwardness in the sharp edge movement has kept the cost of
the saw machine generally less expensive than different kinds of sawing machines.

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In hack sawing, a solitary sharp edge is tensioned in the bow and responded forward and
backward finished the work piece. The cutting activity is accomplished just amid half of the
cycle of task. Amid the second 50% of the cycle at the arrival stroke, the sharp edge is lifted
clear of the work piece giving a spasmodic cutting activity which is thought to be one of the
disadvantages of the task. In spite of this inconvenience, when contrasted with the consistent
cutting activity of the band saw, hacksaws remain similarly or much more famous elective
machines.
Parts of the Powered Hacksaw Machine
 Base
 Frame
 Vise.
Base
The base of the saw usually contains a coolant reservoir and a pump for conveying the
coolant to the work. The reservoir contains baffles which cause the chips to settle to the bottom
of the tank. A table which supports the vise and the metal being sawed is located on top of the
base and is usually referred to as part of the base.
Frame
The frame of the saw supports and carries the hacksaw blade. The machine is designed so
that the saw blade contacts the work only on the cutting stroke. This action prevents unnecessary
wear on the saw blade. The cutting stroke is on the draw or back stroke.
Vise
The vise is adjustable so that various sizes and shapes of metal may be held. On some
machines the vise may be swiveled so that stock may be sawed at an angle. The size of a power
hacksaw is determined by the largest piece of metal that can be held in the vice and sawed.
ii. Bandsaw Machine
The band saw employs an endless flexible steel band with teeth on one edge and the band
is carried on two large-diameter rotating wheels mounted on parallel axes some distance apart.
Band saws that cut vertically are particularly suitable for cutting out shapes in thin, flat plates
from work pieces that lie on horizontal tables. Metal-cutting band saw machines fall into two
basic categories: vertical machines and horizontal machines. Band saws use a continuous saw

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blade, therefore chip removal is rapid because each tooth is a precision cutting tool and accuracy
can be held to close tolerances eliminating or minimizing many secondary machining operations.
Vertical Band Sawing Machine
The metal-cutting vertical band sawing machine also called a contour machine is made in
a variety of sizes and models by several manufacturers. The size of a contour machine is
determined by the throat depth, which is the distance from the saw band to the column. A vertical
band saw keeps the blade's path stationary while the work piece is moved across it. This type of
saw can be used to cut out complex shapes and angle. The part may be fed into the blade
manually or with a power assist mechanism.
Horizontal Band Saw Machine
The horizontal band sawing machine does the same job as the power hacksaw but does it
more efficiently. The blade of the band saw is actually a continuous band which revolves around
a drive wheel and idler wheel in the band support frame. Two band guides use rollers to twist the
band so that the teeth are in the proper cutting position. The guides are adjustable and should be
adjusted so that they are just slightly further apart than the width of the material to be cut.
This work proposes the prototype model of motorized hacksaw machine which is able to
cut piece without any jerk and minimum vibrations. The prototype model implies conversion of
rotary motion into the reciprocating motion for proper working of hacksaws. This prototype
model overcomes the limitations of conventional hacksaw machines which can cut single piece
at a time and is able to cut metal bars of different materials at same time and will be helpful in
many industries due to its compatibility, reliability and efficiency. The machine can be utilized
as a part of remote spots where power is customary; it is planned as a versatile one which can be
utilized for cutting in different spots. It can be utilized for working on materials like thin metals,
wood and other related materials. (Zoeb khan, 2011).
2. MATERIALS AND METHODS
Materials
 Mild Steel Angle Iron (1½inch×1½inch×5mm)
The base frame is the most important component of design, as it is the component which will
hold all the vibrations and hold the cutting operation. The material used to fabricate the base
frame is Angle iron. 5mm Angle iron was used for the base frame, and the material was used due

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to its machinability, good tensile strength, durability, toughness, malleability, ductility and
availability in a wide range of dimensions.
Figure 1: Mild Steel Angle Iron (1½inch×1½inch×5mm)
 Mild Steel Flat Bar (1½inch × 3mm)
A 3mm Flat bar was used as adjoining bar to connect the main frame at the top where the
hacksaw lever was fixed, in other to give rigidity and support due to its thickness and tensile
strength which makes it able to withstand any stress that may be exerted by the load.
Figure 2: Mild Steel Flat Bar (1½inch × 3mm)
 Mild Steel Square Pipe (1inch and 2inches)
1inch square pipe was used as part of the main frame where the hacksaw lever and vise are fixed
upon while the 2 inches square pipe was used as a lever in which the hacksaws was fixed in.
Figure 3: Square Pipe (2inches)

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 Hacksaw
Hacksaw which is the tool performing the cutting operation was fixed to a lever, which enables it
to move front and back while being connected with a connection link bar to a shaft on the motor.
A hacksaw is a fine-tooth saw with an edge under pressure in a casing. Handheld hacksaws
comprise of a metal edge with a handle and sticks for joining a thin dispensable cutting edge. A
screw or other system is utilized to put the thin cutting edge under pressure.
Figure 4: Hacksaw
 AC Motor
An AC motor is an electric motor, powered by an alternate current (AC). The AC motor usually
comprises of two essential parts, an outside stationary stator having loops provided with
substituting current to deliver a pivoting attractive field and an inside rotor connected to the yield
shaft creating a second turning attractive field. The rotor attractive field might be created by
lasting magnets, hesitance saliency, DC or AC electrical windings. The responding movement of
the hacksaw sharp edge is as a result of how the cutting procedure happens and is delivered with
the assistance of an AC motor which works by a basic shaft component to change over rotating
movement of shaft into responding movement hacksaw edge. The AC motor is turned on after
the work piece has been immovably fit into the vise.
Figure 5: AC Motor

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 Vise (3 inches)
A vise is a job or work piece holding device, which is a mechanical apparatus used to secure an
object to allow work to be performed on it. A Vise consists of two parallel jaws one is fixed and
the other one is movable, threaded in and out by a screw and lever. The vise is fixed on the
machine frame at a given distance, so as to provide necessary force for holding work piece
during machining and also for reducing the vibrations generated due to machining.
Figure 6: Vise (3inches)
Fabrication Process and Procedures
This contains the process, methods and procedures involve in fabricating the motorized double
hacksaw machine. The procedures include the following: Measuring and marking out, cutting,
drilling, assembling, tacking, welding, grinding, effective surface preparation and painting.
Figure 7: Measuring and marking out processes
Design Specifications
 Base Frame
Materials used: Mild steel angle iron (1½inch × 1½inch × 5mm)
Dimensions: Length = 750mm Breadth = 300mm Height = 400mm.
 Lever Support
Materials used: Mild steel square pipe (1inch × 1.2mm)
Dimensions: Length = 250mm Hole diameter = 8.5mm

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 Adjoining Bar
Material used: Mild steel flat bar (3mm × 1½inch).
Dimensions: Length = 790mm Hole diameter = 8.5mm
 Motor Sitting
Material used: Mild steel angle iron (1½ inch × 1½inch × 5mm)
Dimensions: Length = 300mm Hole diameter = 8.5mm
 Hacksaw Lever
Material used: Mild steel square pipe (2inches × 1.5mm)
Dimensions: Length = 500mm Hole diameter = 8.5mm
 Hacksaw Connecting Bar
Material used: Mild steel flat bar (1½inch × 3mm)
Dimensions: Length = 400.5mm Hole diameter=8.5mm
 Vise Sitting
Material used: Mild steel square pipe (1½inch × 1½inch × 1.5mm)
Dimensions: Length = 240mm Breadth = 300mm Hole diameter = 8.5mm
 Frame work
Dimensions: Length: 750mm Breadth: 300mm Height: 400mm
3.0 DESIGN CALCULATIONS AND RESULTS
Design Calculations
Selection of Motor
An AC motor was selected which have the following specifications:
Table 1- Motor Specifications
Power 25w
Current 0.35A
Voltage 220v
Frequency 50Hz
Speed 1250rpm
Calculation for Ac Motor:
From physics,

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Power = Torque × Angular Velocity
Torque = Power /Angular Velocity
Power = 25watt
Angular Velocity (ω) = speed in rpm × 2 × 𝜋
= 1250 × 2 × 3.142
= 7885 rad/sec.
Now Torque (T), is a measure of the force that can cause an object to rotate about an axis:
T = Power / Angular Velocity
T = 25 / 7885
T = 0.003Nm
Scotch Yoke Mechanism
Shaft diameter: 10mm Stroke Length: 101.6mm
Calculation for Scotch Yoke Mechanism
The following are some of the theoretical relationships that were used in the course of
carrying out the experimental evaluation for the procedure.
Linear velocity calculation using angular Speed Measurements:
Figure 8: Scotch Yoke Mechanism
Angular velocity (ω)
ω = 2∗𝜋∗𝑟𝑝𝑚
60
ω = 2 × 3.142 × 1250
60
= 130.92 rad/sec
Linear Velocity (v)
v = r × ω
v = 0.0514 × 7855
v = 403.75m/s.

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The torque rating was established and the electric motor selection was warranted. The
torque ratings according to the idealized experimental set up must be computed. Motor Torque
for a horizontal travel on a contact surface, the value of torque is given by:
T = ½ 𝐷 ∗ µ ∗𝑀∗𝑔
µ= coefficient of friction (steel on steel = 0.57)
M= mass of blade (0.38 kg)
g =acceleration due to gravity (9.81)
T = ½ × 0.102 × 0.57 × 0.38 × 9.81
T = 0.108Nm
Selection of Hacksaw Blade
In choosing a hacksaw blade, there is need to ensure that at least three teeth are engaged in
the work piece when cutting. Thin materials on the other hand require finer teeth (higher TPI
numbers) than thick materials. On the back stroke of the blade, no downward pressure should be
applied. One of the most significant factors to consider when choosing a hacksaw blade for a
specific material is the tooth per inch (TPI). TPI has an impact on hacksaw blade cutting
performance and longevity.
Table 2: Hacksaw Blade Specifications
Blade Width (mm) Materials to cut
14 Aluminum and other soft materials.
18 General workshop cutting.
24 Steel plates up to 5/6mm.
32 For cutting hollow section and tubing.
Figure 9: Blade Layout

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Cutting Force
Force, 𝐹𝑐, required for the cutting;
𝐹𝑐 = 𝑍×𝐾 × 𝐴 × 𝑓 x g
Where, Fc = Cutting force in N.
Z = Number of teeth in contact with work piece = 4
K = Specific pressure of cutting = 1.25 𝐾𝑔/mm2
A = Width of saw = 14𝑚𝑚
f = Feed per stroke = 0.25𝑚𝑚
𝐹𝑐 = 4 × 1.25 × 14 × 0.25 x 9.81
𝐹𝑐 = 171.68N.
Figure 10: Motorized Double Hacksaw Machine.
4.0 RESULTS, DISCUSSIONS AND CONCLUSIONS
Results
Several materials are cut using the motorized double hacksaw machine and conventional
hand saw. The times taken to cut each material are recorded below:
Table 3: Motorized Double Hacksaw (MDH) and Conventional Hand Hacksaw (CHH)
S/N Materials Time taken
MDH CHH
1 1inch M/s square pipe 45sec 28sec
2 2inches M/s square pipe 53sec 40sec
3 1inch galvanize round pipe 1min,53sec 1min, 20sec
4 16mm M/s round rod 4min,20sec 2min, 18sec
5 12mm rod 2min 1min, 12sec
6 1½inch×1½inch square pipe 1min 33sec
7 1½inch plastic pipe 20sec 10sec

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Discussions
From the results and graph above, it is obvious that there was a marginal increase in time
taken by the motorized hacksaw machine compared to the conventional hacksaw due to the
following reasons:
i.) The cutting force (forward and backward stroke) exacted by the handheld hacksaw is more
than the motorized hacksaw machine, thereby making the time taken to cut to be less.
ii.) The motorized double hacksaw machine cut two work-pieces at once while the conventional
handheld hacksaw only cut one work-piece. The motor driving the two hacksaws of the
motorized hacksaw machine requires torque and angular velocity (force and time rate to rotate
about an axis) before enabling cutting, which can be considered to take some few times
(seconds) unlike the conventional handheld hacksaw that does not require torque or angular
velocity before enabling cutting. Thereby, the cutting time taken is less to that of the motorized
double hacksaw machine.
Conclusions
Due to the ease of operation and low cost, the suggested model of a motorized double
hacksaw machine is useful in overcoming problems with conventional hacksaw and meets all of
the expectations needed in the micro industries. It can endure vibrations, has no jerk dangers and
requires no special training to operate. Other hacksaw machines can only cut one piece at a time,
but this one can cut two. In comparison to other hacksaw machines, this one is lighter and
portable. The machine is inexpensive, simple to run and suitable for all industries. In comparison

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to normal hacksaw machines, a programmed two-fold hacksaw machine provides exceptional
efficiency in a short period of time. The true advantage of this machine is that work interference
is minimized to the greatest extent possible.
The motorized double hacksaw machine is a very sophisticated machine that is highly
recommended in all areas of fabrication. The machine has the ability to cut two work-pieces at
once. The cutting angle must be gotten right to ensure a perfect cut.
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APPENDIX
Orthographic and Isometric projections of the Motorized Double Hacksaw Machine