DJJ10033: WORKSHOP TECHNOLOGY

CHAPTER 1: HAND TOOLS

1.0 INTRODUCTION
Mechanical Engineering Workshop is a place where students acquire knowledge on the operation of
various processes involved in manufacturing and production. The Workshop Practice course makes
students competent in handling practical work in engineering environment.
Hand tools are used to remove small amounts of material, usually from small areas of the
workpiece. This may be done because no machine is available, the workpiece is too large to go on a
machine, the shape is too intricate or simply that it would be too expensive to set up a machine to do
the work.
Since the use of hand tools is physically tiring, it is important that the amount of material to be
removed by hand is kept to an absolute minimum and that the correct tool is chosen for the task.
Wherever possible, use should be made of the available powered hand tools, not only to reduce fatigue
but also to increase the speed of the operation and so reduce the cost.

1.1 COMMON HAND TOOLS

1.1.1 HACK SAW
The Hack Saw is used for cutting materials by hand. It consists of a renewable hardened steel saw blade
fitted into an adjustable frame, which is usually provided with a screw adjustment for controlling the
tension of the blade. It is necessary to have both junior and senior hack saws in your tool kit.

There are two types of hacksaw frames:

i) Solid hacksaw frame
In this type, only one particular standard length of blade can be used with this frame.
ii) Adjustable hacksaw frame

1
 In this type different standard lengths of blades can be fitted to this frame.

Saw blades:
 Different types of
saw blades are used
depending on the
hardness of the material
to be cut and on the type
of cross-section of the workpiece.
 The blades differ with respect to the saw tooth angles and the number of teeth on a fixed length
of 25 mm (tooth pitch - 1).

Cutting with the hacksaw:

 Hold the hacksaw properly at an angle of 30

 The saw blade is to be clamped so that the teeth are showing into the pushing direction.

 When cutting, move your body rather than just your arms.
 Apply pressure only during the forward stroke (cutting stroke).
 The usual cutting speed is from 40 to 50 strokes per minute.

2
1.1.2 FILES
A file or rasp is used to cut, smooth, or shape parts, usually metal. It can also be used to sharpen other
tools. Files have slanting rows of teeth. Rasps have individual teeth. There is a specific type of file that
is used for different metals. Usually they are classified by their teeth. Sharp and wide-spaced teeth files
are used for soft metals. Less sharp and close teeth files are used for harder metals. Files or rasps do
not usually come with a handle, therefore you should put a handle on the file before using it. After
using a file or rasp, be sure to brush the filings and debris from the teeth with a file card.

Parts of the files

1. Tang
2. Tip or point
3. Face
4. Edge
5. Heel
6. Shoulder
7. Handle

1.1.2.1 File types:

i. Hand file
The hand file is for general use, typically on flat surfaces. It is rectangular in cross-section,
parallel in width along its length, but tapers slightly in thickness for approximately the last third
of its length towards the point. It is doublecut on both faces, single-cut on one edge and is plain
on the second edge. The plain edge with no teeth is known as the ‘safe’ edge and is designed to
file up to the edge of a surface without damaging it. The taper in thickness enables the file to
enter a slot slightly less than its full thickness.

3
 ii. Pillar file
This file has the same section as a hand file but of a thinner section. It is used for narrow slots
and keyways.

iii. Flat file

The flat file is also for general use, typically on flat surfaces. It is rectangular in cross-section
and tapers in both width and thickness for approximately the last third of its length towards the
point. Both faces are double-cut and both edges single-cut. The tapers in width and thickness
enable this file to be used in slots which are narrower than its full width and thickness and
which require filing on length and width.

iv. Square file

The square file is of square cross-section, parallel for approximately two-thirds of its length,
then tapering towards the point. It is double-cut on all sides. This file is used for filing keyways,
slots and the smaller square or rectangular holes with 90° sides.

v. Three-square file
The three-square or triangular file has a 60° triangle cross-section, parallel for approximately
two-thirds of its length, then tapering towards the point. The three faces are double-cut and the
edges sharp. This file is used for surfaces which meet at less than 90°, angular holes and
recesses.

vi. Round file

The round file is of circular cross-section, parallel for approximately two-thirds of its length
and then tapering towards the point. Second-cut and smooth files are single-cut, while the
bastard is double-cut. This file is used for enlarging round holes, elongating slots and finishing
internal round corners.

vii. Half-round file

The half-round file has one flat and one curved side. It is parallel for approximately two-thirds
of its length, then tapers in width and thickness towards the point. The flat side is double-cut
and the curved side is single-cut on second-cut and smooth files. This is an extremely useful
double-purpose file for flat surfaces and for curved surfaces too large for the round file.

4
viii. Knife file
The knife file has a wedge-shaped cross-section, the thin edge being straight while the thick
edge tapers to the point in approximately the last third of its length. The sides are double-cut.
This file is used in filing acute angles.

ix. Dreadnought files

When soft material is being filed, the material is more readily removed and the teeth of an
engineer’s file quickly become clogged. When this happens, the file no longer cuts but skids
over the surface. This results in constant stoppages to clear the file so that it again cuts properly.
To overcome the problem of clogging, files have been developed which have deep curved teeth
milled on their faces. These files are designed to remove material faster and with less effort,
since the deep curved teeth produce small spiral filings which clear themselves from the tooth
and so prevent clogging. Their principal use is in filing soft materials such as aluminium, lead,
white metal, copper, bronze and brass. They can also be used on large areas of steel, as well as
on non-metallic materials such as plastics, wood, fibre and slate. This type of file is available
as hand, flat, half-round and square, from 150mm to 400mm long. The available cuts are broad,
medium, standard, fine and extra fine.

x. Needle files
Needle files are used for very fine work in tool making and fitting, where very small amounts
of material have to be removed in intricate shapes or in a confined space.

1.1.2.2 Grade of cut

When a file has a single series of teeth cut across its face it is known as single-cut file, and with two
sets of teeth cut across its face it is known as double-cut. The grade of cut of a file refers to the spacing
of the teeth and determines the coarseness or smoothness of the file. Three standard grades of cut in
common use, from coarsest to smoothest, are bastard, second cut and smooth. In general, the bastard
cut is used for rough filing to remove the most material in the shortest time, the second cut to bring the
work close to finished size and the smooth cut to give a good finish to the surface while removing the
smallest amount of material.

5
The type of material to be filed, and whether it is a rough or finishing cut, determine the grade of
fineness that is required. Various typical situations may be listed as follows:
(a) For heavy, rough cutting, a large, coarse, double-cut file is best.
(b) For the finishing cut, use a second-cut or a smooth single-cut file.
(c) When filing cast iron, start with a bastard file and finish with a second-cut.
(d) When filing soft steel, start with a second-cut file and finish with a smooth file.
(e) When filing hard steel, start with a smooth file and finish with a dead-smooth file.
(f) When filing brass or bronze, start with a bastard file and finish with a second-cut or smooth file.
(g) When filing aluminium, lead, or metal, use a bastard file, or if available, a float-cut file may be
used. This file has large curved teeth and works with a planning action. It is fitted with a special holder.

1.1.2.3 Filling work

One of the greatest difficulties facing the beginner is to produce a filed surface which is flat. By
carefully observing a few basic principles and carrying out a few exercises, the beginner should be able
to produce a flat surface.
Filing is a two-handed operation, and the first stage is to grip the file correctly. The handle is
gripped in the palm of the right hand with the thumb on top and the palm of the left hand resting at the
point of the file. Having gripped the file correctly, the second stage is to stand correctly at the vice.

6
The left foot is placed well forward to take the weight of the body on the forward stroke. The right foot
is placed well back to enable the body to be pushed forward.
Remember that the file cuts on the forward stroke and therefore the pressure is applied by the
left hand during the forward movement and is released coming back. Do not lift the file from the work
on the back stroke, as the dragging action helps clear the filings from the teeth and also prevents the
‘see-saw’ action which results in a surface which is curved rather than flat. Above all, take your time
– long steady strokes using the length of the file will remove metal faster and produce a flatter surface
than short rapid strokes.
As already stated, a smooth-cut file is used to give a good finish to the surface while removing
small amounts of material. An even finer finish to the surface can be achieved by a method known as
draw filing. With this method, the file, rather than being pushed across, is drawn back and forth along
the surface at right angles to its normal cutting direction.
An even finer finish can be obtained using abrasive cloth supported by the file to keep the
surface flat. Abrasive cloth is available on rolls 25mm wide, in a variety of grit sizes from coarse to
fine. By supporting the cloth strip on the underside of the file and using a traditional filing stroke,
extremely fine surface finishes can be obtained while removing very small amounts of material. This
process is more of a polishing operation.

1.1.2.4 Care of files

A file which cuts well saves you extra work. It is important, therefore, that all the teeth are
cutting. Never throw files on top of each other in a drawer, as the teeth may be chipped. Never knock
the file on its edge to get rid of filings in the teeth – use a file brush. A file brush should be used
regularly to remove filings from the teeth, as failure to do so will cause scratching of the work surface
and inefficient removal of metal. Always clean the file on completion of the job before putting it away.
Do not exert too much pressure when using a new file, or some of the teeth may break off due to their
sharpness – work lightly until the fine tooth points are worn slightly. For the same reason, avoid using
a new file on rough surfaces of castings, welds or hard scale.

7
 Always use a properly fitted handle of the correct size – on no account should a file be used
without a handle or with a handle which is split; remember, one slip and the tang could pierce your
hand.

1.1.3 HAMMER
A hammer is a tool meant to deliver blows to an object. The most common uses are for driving nails,
fitting parts, and breaking up objects. Hammers are often designed for a specific purpose, and vary
widely in their shape and structure. Usual features are a handle and a head, with most of the weight in
the head. The basic design is hand-operated, but there are also many mechanically operated models for
heavier uses.

Parts of Hammer

Face: It is the striking portion polished well and is given slight convexity to avoid spoilage of the
surface of the metal to be hammered.
Peen: It is the other end of the head and is made into different shapes to suit various operations.
Cheek: Middle portion of the hammer head.
Eye-Hole: It is made oval or elliptical in shape to accommodate the handle

1.1.3.1 Types of Hammer

a) Ball Peen Hammer
The ball peen hammer is a hammer used for metalworking. The ball peen has both a flat face and a
spherical face for rounding off (peening) metal. This hammer is commonly used with a chisel or
punch

8
b) Stretching Hammer
This is used for stretching edges and flanges on curved work. It is normally used in conjunction
with a stake.

c) Cross Peen Hammer

This is used for the same operation at right angles with the handle.

d) Straight-peen hammer
This is used for spreading or drawing out metal in line with the handle.

e) Claw hammer
This is used for driving and pulling nails.

f) Soft Hammer or Mallet

These are soft hammers used give light blows where the work surface must not be damaged.
They are made of either rubber, plastic or wood.

9
1.1.3.2 Using a Hammer
When using a hammer, it should be held near the end of the handle with the face of the hammer parallel
to the work. A grip just tight enough to control the blow is best. The correct way to hold a hammer is
shown in figure below.

Always use a hammer which is heavy enough to deliver the required force but not too heavy to
be tiring in use. Keep the hands and the hammer handle free from grease and oil, otherwise the hammer
may slip from the grasp. It should also be remembered that oil or grease on the hammer face may cause
it to slip off the work and lead to a painful bruise.

1.1.4 CHISEL
A chisel is used for carving or cutting wood, stone, and metal. It has a sharpened, sloped (beveled ◊)
edge. There are two types of chisels, wood chisels and cold chisels. Both types of chisels have steel
heads and are able to cut anything that is softer than the steel they are made from.

10
1.1.4.1 Parts of a chisel

All chisel have strong, machine-grade steel blades. They may be hot or cold depending on
whether the metal to be cut is hot or cold. A hot chisel generally used in forging shop. The main
difference between the two is in the edge. The edge of a cold chisel is hardened and tempered with an
angle of about 60°, whilst the edge of a hot chisel is 30° and the hardening is not necessary. The edge
is made slightly rounded for better cutting action.

1.1.4.2 Types of cold chisel

1) Flat chisel – is used for chipping flat surface, cutting off rivets or metal fasteners, thin sheets, small
bars, and for general purposes. Its cutting edge ranges from 13 to 25mm.

2) Cape chisel- has a narrow edge suited for cutting narrow grooves or slots.

11
3) Diamond-point chisel –has a diamond shape cutting edge intended to cut V grooves.

4) Round-nose chisel – has a round nose cutting edge for cutting round and semi-circular grooves.

1.1.4.3 Using a chisel

Chisel are used with hammer in a two handed operation; one hand holds the chisel against the work
and the other hands taps the hammer against the chisel to make the cut.
Always wear the appropriate PPE (safety glasses and gloves). Periodically sharpen the cutting
edge of the chisel. Avoid using a chisel head that has become mushroomed, flattened, or damaged.

1.1.5 TAPS
A tap is a screw like tool which has threads like a bolt and three or four flutes cut across the threads
which is used to produce internal threads. The edge of the thread formed by the flutes are the cutting
edges. The lower part of the tap is somewhat tapered so that it can well attack the walls of the drill
hole.
Hand taps are usually made in sets of three (1) Taper tap (2) Second tap
(3) Bottom tap.

(1) Taper tap: In this tap about six threads are tapered and is used to start the thread, so that the
threads are formed gradually as the tap is turned into the hole.

12
 (2) Second tap: It is tapered back from the edge about three or four threads used after taper tap. It
has been used to cut the threads as far as possible.

(3) Bottom tap: It has full threads for the whole of its length. This is used to finish the work
prepared by the other two taps.

1.1.5.1 Using Taps

A hole must be drilled to the tapping size for the thread. The workpiece must be securely supported.
When starting the cutting, the tap must be perpendicular in all planes to the work. Excessive force must
not be used, as this will result in breaking the tap. Cutting fluid should be used. The threads must be
cleared as often as is necessary to prevent the flutes from clogging.

Care must be taken not to damage the cutting edges. A chipped tap must never be used. When not in
use, taps should be kept clean and stored in a rack.

13
1.1.6 DIES
It is a circular disc of hardened tool steel used to make external threads on a round rod or bolts with a
die and stock. Die has a hole containing threads and flutes which form cutting edges.

1.1.6.1 Types of Dies

There are button dies, half dies and solid die nuts.

The Button Die

The button or split die allows a limited amount of adjustment in the depth it will cut, by means of
screws in the stock which spring it open or shut. It should be fully open for the first cut and then
gradually reduced to finished size. It must be checked against an existing thread or die nut of correct
size.

Half Dies
Half dies have the advantage of taking smaller cuts to reach correct size, so the amount of material
taken off can be controlled. Half dies are in matched pairs, and should always be used together.

1.1.6.2 Using Dies

The work should be chamfered for ease of starting. The workpiece must be securely supported and
vertical in the vise. Great care must be taken to start the thread true to the axis of the bar. Lubricant
should be used. The threads must be cleaned as often as is necessary.

14
1.2 MEASUREMENT -Measuring Tools

1.2.1 Rulers
Rules are used for measuring dimensions. For measuring and setting out dimensions various types of
rules are used in carpentry shop. Steel Rule- Stainless Steel Rule of length 30cm and 60cm. Flexible
Measuring Rule- for measuring large dimensions as well as curved or angular surface dimensions.

1.2.2Calipers
These are used for measuring and transferring the inside or outside dimensions for components. These
are also used for comparing the sizes with existing standards. The following types of calipers are most
widely used in workshops:
1. Outside Calipers
2. Inside Calipers

1. Outside Calipers
It is used for measuring outside dimensions of cylindrical shapes and the thickness of metal pieces. It
has two steel legs bent inwards.

15
2. Inside Calipers
It is used to measure the diameter of holes and width of key ways or recesses. Its legs are bent outwards.

1.2.3 Vernier Calipers

These are widely used for precision measurement of length, thickness, depth and inside and outside
diameters. It has locknut which is very useful to keep the measurement permanently.
The example shown below is a manual caliper. Measurements are interpreted from the scale by
the user. This is more difficult than using a digital vernier caliper which has an LCD digital display on
which the reading appears. The manual version has both an imperial and metric scale. Manually
operated vernier calipers can still be bought and remain popular because they are much cheaper than
the digital version. Also, the digital version requires a small battery whereas the manual version does
not need any power source.

16
1.2.3.1 Parts of vernier calipers
1. Outside jaws: Used
to measured external
diameter or width of an
object
2. Inside jaws: Used
to measure internal
diameter of an object
3. Depth probe: Used to measure depths of an object or a hole
4. Main scale: Scale marked every mm (metric scale)
5. Main scale: Scale marked in inches and fractions (Imprial scale)
6. Vernier scale: Gives interpolated measurements to 0.1mm or better
7. Vernier scale: Gives interpolated measurements in fractions of an inch.
8. Retainer: Used to block movable part to allow the easy transferring of a measurement
9. Locking screw: Used to lock movable jaw with main scale.

1.2.3.2 How to read vernier calipers

Example 1: The external measurement (diameter) of a round section piece of steel is measured using
a vernier caliper, metric scale.

Mathematical Method
A. The main metric scale is read first and this shows that there are 13 whole divisions before the 0 on
the hundredths scale. Therefore, the first number is 13.
B. The’ hundredths of mm’ scale is then read. The best way to do this is to count the number of divisions
until you get to the division that lines up with the main metric scale. This is 21 divisions on the
hundredths scale.
C. This 21 is multiplied by 0.02 giving 0.42 as the answer (each division on the hundredths scale is
equivalent to 0.02mm).
D. The 13 and the 0.42 are added together to give the final measurement of 13.42mm (the diameter of
the piece of round section steel)

Common sense Method

Alternatively, it is just as easy to read the 13 on the main scale and 42 on the hundredths scale. The
correct measurement being 13.42mm.

17
Example 2: (To zoom in to see the scale - right click mouse and select zoom)

1.2.4 Micrometer Calipers

Micrometre is a precision tool used to measure external or internal dimensions such as diameters and
thickness, with an accuracy up to 0.001 mm.

18
1.2.4.1 Types of micrometre
A. Outside micrometre
These are typically used to measure wires, spheres, shafts and blocks.

B. Inside micrometre
Used to measure the diameter of holes.

C. Depth micrometre
Measures depths of slots and steps.

1.2.4.2 How to read a micrometre

A micrometre reading contains two parts:
 the first part is contributed by the main scale on the sleeve
 the second part is contributed by the rotating vernier scale on the thimble

19
The above image shows a typical micrometre screw gauge and how to read it. Steps:
 To obtain the first part of the measurement: Look at the image above, you will see a number 5
to the immediate left of the thimble. This means 5.0 mm. Notice that there is an extra line below
the datum line, this represents an additional 0.5 mm. So the first part of the measurement is
5.0+0.5=5.5 mm.
 To obtain the second part of the measurement: Look at the image above, the number 28 on the
rotating vernier scale coincides with the datum line on the sleeve. Hence, 0.28 mm is the second
part of the measurement.

Add the first part and second part of the measurement to obtain the micrometre reading: 5.5+0.28=5.78
mm.

20