MODULE TITTLE: PERFORMING POWER SAWING

UNIT TITTLE: PERFORMING STRAIGHT CUTTING

ELEMENT: PERFORM VERTICAL /STRAIGHT CUTTING
Power hacksaw machine-Is the machine tools which is used primarily for cutting standard stock
to working length in the machine shop.
TYPES OF POWER HACKSAW MACHINE
There are four (4) the main types of power hacksaw machine in the machine shop such as
follows:
[i] Power hacksaw machine
[ii] Horizontal/Band saw machine
[iii] Cold saw machine
[iv] Abrasive cut-off saw machine

[I] POWER HACKSAW MACHINE

Power hacksaw machine this is a type of machine which is operate on the principle of the
reciprocating stroke in the machine shop when perform metal cutting process that can be done
straight cutting or angle cutting.

[II] HORIZONTAL/BAND SAW MACHINE

Horizontal/band saw machine this is a type of machine which is operate on the principle of
continuous rotating of the saw cutting rates are higher as the endless blades cut continuously.

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 [III] COLD SAW MACHINE
Cold saw machine also this is the type of machine which are low r.p.m circular saw designed
especially for cutting metal in the machine shop. They range in size from hand operated bench to
fully automatic machine.

[IV] ABRASIVE CUTT-OFF SAW

Abrasive cut-off machine this also is the type of sawing machine which employs an abrasive disc
to separate the materials by grinding. They are either of manual operated or with power feeds.

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THE MATERIALS USED TO MANUFACTURED BLADE OF POWER SAW MACHINE
Blade of power sawing machine are made of
- Carbon tool steel
- Alloy tool steel
- High speed steel

PARTS OF POWER HACKSAW MACHINE

The following are the main parts of power saw machine such as follow
[i] Base [vi] Cut off gauge
[ii] A saw frame [vii] Handle threaded
[iii] Table [viii] Coolant feed
[iv] Vice [ix] Switch on/off
[v] Motor
SAFETY PRECAUTION WHEN PERFORMING VERTICAL/STRAIGHT CUTTING IN
THE MACHINE SHOP
[i] Mount or remove work only when the machine is stopped and raised well above the vice
[ii] Clamp the work for securely tight, looseness may cause breakage of the blade
[iii] Always wear goggles when working on power sawing
[iv] Use the right blade for the right material
MODULE TITTLE: PERFORMING BENCH WORKS
UNIT TITTLE: PERFORM CHISELING
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Chisel
Is an instrument which is used for chipping out surplus materials outside or inside of the
workpiece.
Chiselling
Is an operation or process of chipping out surplus materials either outside or inside in the
workpiece by using a tool a tool known as chisel, which is made up of steel, in the modern
machine tools the use of chisel have been greatly reduced in the machine shop works. However,
there are time then the use of hammer and chisel is available.
TYPES OF CHISELS
A chisel is divided into four main types such as follows:
[i] Flat cold chisel
[ii]Cape or cross cut chisel
[iii]Round nose chisel
[iv]Diamond point chisel
[I] FLAT COLD CHISEL
A flat cold chisel is the type of chisel it is most commonly used for chipping out surplus
materials. It is also used for cutting thin materials, cutting of head of rivet and removing the weld
sport. The flat cutting edge is slightly wider than the stock and is hardened and tempered.

[II] CROSS OR CAPE CHISEL

Cross or cape chisel this is the type of chisel which has a narrow cutting edge and it is used for
cutting key way and narrow grooves in the metals.

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[III] THE ROUND NOSE OR GROOVING CHISEL
The round nose or grooving chisel is the type of chisel which has a rounded cutting edge and is
used for cutting oil grooves in bearings and for cutting in curved surfaces.

THE DIAMOND POINT CHISEL

The diamond point chisel this is the type of chisel which has a diamond shaped cutting face, it is
used for squaring corners and cutting V-shaped grooves.

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 THE HINTS ON CHISEL USE CHIPPING
[i] Never use a chisel without a mushroom head
[ii] Make sure that the hammer and chisel head are free from grease or oil
[iii] Never try to take too deep a cut, the angle at which the chisel is made determines the
depth of cut.
[iv]When striking a chisel watch the cutting edge and not the head of the chisel.

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MODULE TITTLE – PERFORMING DRILLING WORKS
UNIT TITTLE – PERFORM DRILLING
Drilling machine is the most important machine tools in a workshop designed to produce a cylindrical
hole of required diameter and depth on metal work piece.
Types of drilling machine
Drilling machine are manufactured in different types and sizes according to the type of operation, amount
of feed, depth of cut, spindle speed, methods of spindle movement and the required accuracy. The
following are types of drilling machine
-Portable drilling machine
-Sensitive drilling machine
-Radial drilling machine
-Gang drilling machine
-Multiple drilling machines

Portable drilling machine

This is also known as hand drilling machine. They are commonly
used to drill small holes and as well as opening and closing of
screws.
Sensitive drilling machine
Such type of drilling machine is designed for drilling small holes
at high speeds in light jobs. The base of the machine is mounted
either on bench or on the flow by means of bolt and nut. It can
handle drills up to 15.5mm of diameter.
Radial drilling machine
Radial drilling machine is intended for on medium to large and
heavy work piece. It has a heavy round column mounted on a
large. The column supports the radial arm which can be raised or
lowered to enable the table to accommodate the work piece
position. The arm which has the drill head on it can be swung around any position.
Gang drilling machine
Are drilling machines equipped with more than one work or drilling head mounted on a single table. They
are used when several operations must be performed on a single job.

Multiple drilling machines

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Such type of machine is used for high-speed production work. A number of spindles may be mounted on
a single head.
The basic parts of drilling machine
The main parts of drilling machine are as shown in the figure bellow
①.Belt cover
②.Switch
③.Drill chuck
④.Motor
⑤.Handle
⑥.Pole
⑦.Vice
⑧.Worktable handle
⑨.Worktable
⑩.Base

⑪.Chuck key

-Base the base is made of heavy box type ribbed cast iron or of welded steel. The base is used to bolt the
machine to a floor or bench and also to provide a coolant reservoir.
-Table is used to clamp large work directly for drilling purpose. The table has T- slots on it for holding
the work piece or to hold any other holding device
-Column is an upright cylindrical member fitted to the base which supports the radial arm at right angle
for radial drilling machine
-Drilling head is mounted on the arm and may be moved along the length of the arm by means of a
traverse hand wheel. The head may be clamped at any position along the arm. The head houses the
change gears and controls for the spindle speeds and feeds.
Standard operations
Drilling machines may be used for performing a variety of operations besides drilling a round hole which
are-
-Drilling defined as the operation of producing a hole by removing metal from a solid mass using a
cutting tool
-Sport-facing is the operation of smothering and squaring the surface around a hole to provide a seat for
the head of a cap screw or nut
-Countersinking is the operation of producing a tapered or cone-shaped enlargement to the end of a hole

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-Tapping is the operation of cutting internal threads in a hole with a cutting tool called a tap
-Reaming is the operation of sizing and producing a smooth round hole from a previously drilled or
bored hole with the use of a cutting tool having several cutting edges.
-Boring is the operation of truing and enlarging a hole by means of a single –point cutting tool which is
usually held in a boring bar.
-Counter boring is the operation of producing a straight hole having a square shoulder on the end of an
existing hole to provide a recess for the head of a cap screw or nut.
Work-holding devices
All work pieces must be fastened securely before cutting operations are performed on a drilling machine.
If the work moves or springs during drilling the drill usually breaks. Work-holding devices used on drill
press are-

-Drill vice used to hold round, square, rectangle and odd-shaped pieces for any operation that can be

performed on a drill machine.

-An angle vice this type of vice has an angular adjustment on its base to allow the operator to drill holes
at an angle without tilting the drill table
-V-block are used in pairs with u-clamp to support round work for drilling

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-Step blocks are used to provide support for strap clamps when work is being fastened for drilling
machine operations.

-Angle plate is an L-shaped piece of cast iron or steel machined to an accurate 90 degree.

-Clamps or straps used to fasten work to the drill table or an angle plate for drilling. They are usually
supported at the end by a step block and bolted to the table by a T-bolt that fit into the table T-slot.

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 Drills
Drills are end-cutting tools used to produce holes in most types of material. Two helical grooves or flutes
are cut length wise around the body of the drill. They provide cutting edges and space for the cuttings to
escape in the drilling process. Since this is one of the most efficient cutting tools, it is necessary to know
the main parts, how to sharpen the cutting edges and the correct speeds and feeds for drilling various
metals.
Parts of a drill
A drill may be divided into three main parts which are-
-Shank is the part of a drill which can be straight or taper. Normally drill bit which are less than 12.5mm
have straight shank and those more than 12.5mm have taper shank. Straight shank drills are held in a drill
chuck and tapered shank drills fit into the internal taper of the drill spindle. A tang is provided on the end
of tapered shank drills to prevent the drill from spinning while it is cutting and to allow the drill to be
removed from the spindle or socket without the shank being damaged.
-Body is the portion of the drill between the shank and the point. It consists of the number of parts
important to efficiency of the cutting action which are-.
*Flutes are two or more helical grooves cut around the body of the drill. They form the cutting edges,
admit cutting fluid and allow the chips to escape from the hole.
*Margin/land is the narrow raised section on the body of the drill. Its purpose is to provide a full size to
the drill body and cutting edges.
*Body clearance is the undercut portion of the body between the margin and the flutes. It is made smaller
to reduce friction between the drill and the hole during the drilling
*Web is the thin partition in the centre of the drill which extends the full length of the flutes. It forms the
dead centre at the cutting end of the drill.
-Point is part of the drill bit which consists of dead centre, lips, lip clearance and heel.
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*Dead centre is the chisel shaped portion of the drill point.
*Lips/cutting edges are formed by intersection of the flutes. Must be of equal length and have the same
angle so that the drill will run true.
Lip clearance is the relief which is ground on the point of the extending from the cutting lips back to the
heel.

Twist drill nomenclature

Axis
It is the longitudinal centerline of the drill running through the centres of the tang and the chisel edge.
Body
It is the part of the drill from its extreme point to the commencement of the neck, if present. Otherwise, it
is the part extending upto the commencement of the shank. Helical
grooves are cut on the body of the drill.
Shank
It is the part of the drill by which it is held and driven. It is found just above the body of the drill. The
shank may be straight or taper. The shank of the drill can be fitted directly into the spindle or by a tool
holding device.
Tang
The flattened end of the taper shank is known as tang. It is meant to fit into a slot in the spindle or socket.
It ensures a positive drive of the drill.
Neck
It is the part of the drill, which is diametrically undercut between the body and the shank of the drill. The
size of the drill is marked on the neck.
Point
It is the sharpened end of the drill. It is shaped to produce lips, faces, flanks and chisel edge.
Lip
It is the edge formed by the intersection of flank and face. There are two lips and both of them should be
of equal length. Both lips should be at the same angle of inclination with the axis (59°).
Land
It is the cylindrically ground surface on the leading edges of the drill flutes adjacent to the body clearance
surface. The alignment of the drill is maintained by the land. The hole is maintained straight and to the
right size.
Flutes

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The grooves in the body of the drill are known as flutes. Flutes form the cutting edges on the point. It
allows the chips to escape and make them curl. It permits the cutting fluid to reach the cutting edges.

Speed
Speed of the drill is referred as cutting speed which is the distance that a point on the circumference of
drill will travel in one minute.
Cutting speed (CS) = πdn/1000 m per minutes but the cutting speed for each material normally should be
given.
Feed
Feed is the distance that a drill advances into the work for each revolution
Drill grinding
Before a drill is used is wise first to examine its condition. To cut properly and efficiently, a drill should
have the following characteristics
-The cutting edge should be free from wear
-Both cutting edges should have the same angle

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 -Both cutting edges should be the same length
-The land or margin should be free of wear
-There should be a proper amount of lip clearance
The following are angles to be obtained when grinding
For general purpose, drill should have an included point angle of 118°.
60°-90° for soft material and 135°-150° for hard material.
CUTTING FLUIDS/COOLANT
Cutting fluids are essential in most metal cutting operations. During a machining process, considerable
heat and friction are created by the plastic deformation of metal occurring in the shear zone when the chip
slides along the chip-tool interface. This heat and friction cause metal to adhere to the cutting edge of the
tool and the tool may break down and result in poor finish and inaccurate work.
PURPOSE AND ADVANTAGES
During machining process considerable heat and friction are created. So we use cutting fluids so as to
cool the workpiece, to dissipate heat, to cool the tool, to reduce friction and wear, to improve the tool life,
to flush away the chips, to improve the surface finish of workpiece and to reduce cutting force and energy
consumption. Their use can result in the following economic advantages.
~Reduction of tool costs – cutting oils reduces tool wear; they rust longer and less time is spent in
resharpening and resetting.
~Increase speed of production - because cutting oils helps to reduce heat and friction hence high cutting
speed may be used for machining operation
~Reduction of labour costs – as cutting tool rust longer and require les regrinding when cutting oil are
used, there is less stoppage of production hence reducing the labour cost per part.
~Reduction of power costs – since friction is reduced by a cutting fluid, less power is required for
machining operation and a corresponding saving in power costs is possible.
CHARACTERISTICS OF A GOOD CUTTING FLUID
For a cutting fluid to function effectively it should possess the following desirable characteristics
~Good/high cooling capacity to reduce the cutting temperature, increase tool life and improve
dimensional accuracy
~Good lubricating qualities to reduce the friction force between work and tool.
~Corrosion and Rust resistance-it should not cause stain, rust or corrosion to the work peace or machine.
~Stability and long life both in storage and in use.
~Nontoxic – it should not cause skin irritation to the operator
~Transparent – so that the operator can clearly see the work during machining.
~Relatively low viscosity to permit the chips and dirt to settle quickly.
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~Non-flammable and non-Smokey– it should not burn easily and should preferably be non-combustible
and should not smoke excessively.

TYPES OF CUTTING FLUIDS

The most commonly used cutting fluids are either aqueous (water) based solution or cutting oils. These
fluids fall into three categories which are-
~Straight oils – They are also known as neat cutting oils. They use non-emulsifiable mineral oils without
the addition of water. They provide excellent lubrication, good corrosion protection but they possess poor
heat removal capabilities.
~soluble oils an effective cutting fluid should possess high heat conductivity and neither mineral nor fatty
oils are very effective as coolants. Water is the best cooling medium known, however, used as a cutting
fluid and water alone would cause rust and have little lubricating value. By adding a certain percentage of
soluble oil to water it is possible to add rust resistance and lubrication qualities to the excellent capacity
of water. Soluble oil is a mineral oil containing soap like material (emulsifier) which makes them soluble
in water. These emulsifiers break the oil into minute particles and keep them separated in the water for
long period of time.
~Chemical cutting fluids – sometimes called synthetic fluids have been widely accepted since they were
first introduced about 1945. They are a mixture of soluble oils (emulsions) and water-based fluids. They
are stable pre-formed emulsions which contain very little oil and mix easily with water.

MODULE TITTLE: PERFORMING BENCH WORKS

UNIT TITTLE: PERFORM THREADING
ELEMENT: PERFORM TAPPING
Taps: these are the hand cutting tools which are used for cutting internal threads which the use
of tap wrench, they are made of high-quality steel and hardened.
Tapping: tapping is an operation or process of cutting internal thread by using a tap and tap
wrench. Thread is the uniform helical ridges formed on a round object outside or inside in the
workpiece.
Threading is an operation or process of forming uniform helical ridges formed on a round object.
TYPES OF TAPS

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 Tap are divided into three types such as follows:
[i] Taper tap
[ii] Plug tap
[iii] Bottoming tap
[I] TAPER TAP
Taper tap this is the type of tap which is tapered from the end is used for starting a thread easy.

[II] PLUG TAP

Plug tap this is the type of tap which is tapered for approximation, these thread sometimes it is
used to cut threads on through holes.

[III] BOTTOMING TAP

Bottoming tap this also is the type of tap which is not tapered but chamfered at its end, it is used
for threading to the bottom of holes. When tapping a blind hole fist use the taper tap, plug tap
and complete that with bottoming tap.
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 A TAP WRENCH:
The tap wrench this is the handle which is used to hold a tap when performing tapping, tap
wrench is divide into two types such as follows.
[i]T-handle tap wrench
[ii] Double- ended adjustable tap wrench

Some taps are identified by rings in their shanks and these are as follows:
[i] Having one ring
[ii]Having two rings
[iii] Having three rings
THE TAP DRILL SIZE (T.D.S)

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Before a tap is used, the holes must be drilled to the correct tap drill size,the tap drill size is the
size of the drill that should be used to remove proper amount of materials in the holes for a tap to
cut the threads.
CALCULATION OF TAP DRILL SIZE (T.D.S)
By the formular
T.d.s =M D-(0.5413x2P)
Where by
D=Major diameter of the workpiece
P=Thread pitch
Example 01: Find the tap drill size of M10x1.5P.
Solution: But from the formula T.d.s=MD-(0.5413x2p)
T.d.s=10-(0.5413x2x1.5)
= 10-(0.5413x3)
= 10-1.89455
= 8.4mm
Therefore, the tap drill size is 8.4mm.
Example 02: Find the tap drill size of M12x1.75P
Solution: But from the formular T.d.s=MD-(0.5413x2P)
T.d.s=12-(0.5413x2x1.75)
=12-(0.5413x3.5)
=12-1.89455
=10.1054mm
Therefore, the tap drill size is 10.10545mm Ans.
Example 03: Find the tap drill size of M14x2P
Solution: But from the formular T.d.s =D-(0.5413x2P)
= 14-(0.5413X2X2)
=14-(0.5413X4)
=14-2.1652
=11.8348mm
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 The tap drill size is 11.8348mm Ans.
TOOLS AND EQUIPMENTS USED IN TAPPING PROCESS:
TOOLS
[i] Vernier calliper
[ii] Vernier height gauge
[iii] Scriber
[iv] Drill bit or twist drill
[v] Taps
[vi] Tap wrench
EQUIPMENTS
[i] Bench work
[ii] Surface plate
[iii] Drilling machine
[iv] Oil and oil can
SAFETY REQUIREMENTS WHEN PERFORMING TAPPING:
[i] When performing tapping apply oil in order to reduce heart.
[ii] Easy turn back the tap at the interval of two turns to ensure undamaging of thread and tap as
well.
[iii] Select the proper tap and tap wrench.

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MODULE TITTLE: PERFORMING BENCH WORK
UNIT TITTLE: PERFORM THREADING
ELEMENT: PERFORM DIE CUTTING
A DIE
A die is a tool which is used for cutting external threads on a cylindrical part such as bolts, stud
and so on. In this operation the device used to hold the die is called die stock
DIE CUTTING
A die cutting is an operation or process of cutting external threads on a cylindrical part such as
bolt and stud.in this operation the device used to hold the die is called die stock.
TYPES OF DIE:
There are various forms of die and these are:
[i] Adjustable round sprit-die
[ii] Adjustable two-piece die
[iii] Solid die nut

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 [I] ADJUSTABLE ROUND SPRIT DIE
Adjustable round sprit-die this is a single piece adjustable die which is always mounted in a die
stock when performing hand threading.

[II] ADJUSTABLE TWO-PIECE DIE

This is the types of die which is consist a pair of die or jaw which fit into the stock and are
clamped by screw ring, these dies slide and may be adjusted by screw which bear against their
outer faces.

[II] SOLID DIE NUT

A solid die nut or solid die is designed primary for dressing or cleaning up bruised or damaged
thread.no special holder is used to turn the die, die is manufactured from high-speed steel.

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 DIE CUTTING ALLOWANCE
The major diameter of a shaft bolt or stud to be cut the thread can be calculated by using the
following formula.
MD=(BD-1/10PITCH)
Where MD=major diameter
BD = Bolt diameter
P =Pitch
Example 01: Calculate the major diameter required for cutting external threads of M14x2p.
Solution
Where BD = 14mm
P = 2mm
But from the formula MD = (BD – 1/10Xp)
= 14 – 1/10x2
= 14 – 1/5
BD = 13.8mm
The major diameter is to be turned is 13.8mm Ans.
Example 02: Calculate the major diameter required for cutting threads of bolt diameter is
M12x1.5P
Solution

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 Where BD = 12mm
P = 1.5mm
But from the formula MD = (BD – 1/10XP)
= 12 – 1/0X1.5
= 12 – 1/10x3/2
= 12 – 3/20
MD = 11.85mm
The major diameter is to be turned is 11.85mm Ans.
Example 03:
Calculate the major diameter required for cutting threads of bolt diameter M10x1.25mm
Solution
Where BD = 10mm
P = 1.25mm
But from the formula MD = BD – 1/10xP
= 10 – 1/10x1.25
= 10 – 0.125mm
= MD = 9.88mm
The major diameter is to be turned is 9.88mm Ans
SAFETY REQUIREMENTS WHEN PERFORMING DIE CUTTING
[i] Always apply oil when perform cutting of threads
[ii] Do not use excessive power when cutting threads
[iii] Make sure die does not rotate on within the stock
STEPS WHEN PERFORMING THREAD CUTTING BY USING A DIE
[i] Read and interpret the drawing
[ii] Select tools and equipment required
[iii] Chamfer the workpiece to the required depth of thread
[iv] Clamp the workpiece in a bench vice
[v] Fix die in the die stock

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 [vi] Cut thread, apply oil after every half turn of a cut
[vii] Clean the workpiece, tools and store in their right place.

MODULE TITTLE: PERFORMING BENCH WORKS

UNIT TITTLE: PERFORM PUNCHING/STAMPING
ELEMENT: PERFORM LETTERING AND NUMBERING
Letter punch/number punch
[I] LETTER PUNCH
Letter punch this is the hand tools which is used to mark alphabets in the workpiece.

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 [II] NUMBER PUNCH
Number punch this is the hand tools which is used to mark a number in the workpiece.
Materials to manufactured letters punch or number punch is High-speed steel or High-carbon
steel.

PUNCHING STEPS
[i] Read and interpret the drawing
[ii] Identify tools and equipment
[iii] Mark or layout
[iv] Set the distance use divider
[v] Perform punching of letter or number.
[vi] Clean the workpiece and keep tools in store
PUNCHES
Punches are the hand tools which is used to layout workpiece.
TYPES OF PUNCHES
[i] Centre punch
[ii] Dot punch
[iii] Pin punch
[I] CENTRE PUNCH
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The centre punch these are the hand tools which is used to mark a centre in the workpiece before
drilling the holes, the centre punch is grinded at 60 -30degrees.

[II] DOT PUNCH

The dot punch these are the hand tools which is used to mark a dot before drilling chain holes,
dot punch is grinded at 60 - 90 degrees.

[III] PIN PUNCH

The pin punch these are the hand tools which is used to remove out the piece of pins or key in
the workpiece
Materials used to manufacture punches are High-speed or High-carbon steel.

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