18.1A Use hand tools
Topic One – Introduction
INTRODUCTION TO HAND TOOLS
General engineering hand tools are used in many different occupations
Their design, general safety and general classifications are explained in this section.
The methods of use are written for a right-handed person. Left-handed will have to change the various stances and
positions.
NOTE:
It is important to carefully follow the instructions supplied by manufacturers of tools. If the tools are not used
regularly, their instruction sheets must be kept for quick reference.
Definitions
Hand tools have been designed to apply one or more
Principles of science of mechanics to make tasks easier.
When you have used hand tools, you have used many of
these principles even if you don not know the ideas
behind them.
The lever
The lever makes use of mechanical advantage to
produce a large force at one end by applying a relatively
small effort at the other. It is used for pushing, pulling,
lifting, lowering and praising.
To do this, a point of support (fulcrum or pivot point, F) is
needed somewhere along the lever. The illustrations
show two types of lever:
 One with the fulcrum between the two forces
acting on the lever and close to the load move.
 The other with the fulcrum at one end of the
lever instead of between the two forces, but still
close to the point where the shifting force is
needed.
The first type of lever is used to lift or to praise; the
second, to push or pull.
From the illustrations you can see that the closer the
load is to the fulcrum and the longer the lever is on which
you have to apply the effort, the easier it will before you
to shift a big load.
Also, the closer the load is to the fulcrum, the smaller the
distance is over which you can shift the load in any one
movement of the lever.
This principle is called Leverage and is related to the
length of the tool and the applied force. More leverage
can be applied with a longer tool than can be applied
with shorter tool. The unit for leverage is the Newton
meter (Nm).
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18.1A Use hand tools
Topic One – Introduction
The crank
The crank is used for changing a force that acts along a
straight line into a rotating force. Pedals on a bicycle are
crank, and some hand tools operate as cranks.
When a force acts to turn an object about its axis, the
turning effect produced is called the ‘turning moment’ or
Torque. The turning moment is equal to the applied
force times the length of the lever. That is, torque
(turning effect) is the result of the applied force times
(multiplied by) the perpendicular distance between the
applied force line and the pivot point.
The unit for torque is the Newton meter (Nm).
For example, if we apply a force of 100 Newton to a
lever of 0.5 meter, the resultant torque will be:
T=100X0.5=50Nm.
Torque causes parts to twist around their axis or center
point.
When using a cranked tool you will get the maximum
effect if you apply the force at right angles to the plane of
the crank, since this will produce maximum torque.
In the diagrams, a brace is shown turning about its axis
for a quarter of a turn under the action of a force that
acts vertically downwards. The distance from the axis
decreases from maximum to zero. This causes the
torque, or turning moment, exerted by the force to
decrease also.
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18.1A Use hand tools
Topic One – Introduction
Applied force
Applied force is the degree of push or pull given to the
tool by its operator. Applied force is measured in Newton
(N).
Pressure
A force applied to a very small area will result in great
pressure on that surface. A large mass that takes up a
large surface area will produce far less pressure than
when that same mass concentrated on a small area.
Note how pressure is applied in the use of various hand
tools.
Chisels and other hand tools used to cut metal apply the
principle of pressure by concentrating force on a very
small area and that of wedging to cut and separate at the
same time.
The inclined plane
It is easier to pull a load up over a ramp (inclined plane)
than to pull it up vertically.
Wedges and screws are useful small-scale applications
of the principle of inclined plane.
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18.1A Use hand tools
Topic One – Introduction
Tension
Tension means stretching. That is, when a bolt is
tensioned its length increases by a very small amount.
Tightening
Tightening is the result of applying a torque to a nut so
that the thread angle can tension the bolt.
NOTE:
The applied torque will also twist the bolt. This can be
removed by turning the nut slightly backwards.
Many hand tools are simple machines. You apply the effort. They help you to do work because many simple
mechanical principles are applied.
Learning how hand tools cut will help you understand the cutting action use in machining metals.
Learning to understand hand tools, as simple machines will help you understand more complex ones. Try to reason
out why hand tools are designed as they are, what they are use for, and why certain materials are used in them. This
will help you get better use from your hand tools.
Hand tools classifications
Generally hand tools classified as:
 Fastening tools, e.g. spanner and screwdriver
 Gripping and Clamping tools, e.g. pliers and grip
 Impact tools, e.g. hammer and punch
 Marking, Measuring and Gauging tools, e.g. steel rule and scriber
 Cutting tools, e.g. file and hacksaw
 Portable power tools, e.g. portable grind and portable drill
In this module trainees will be introduced to the basic tools they will be required to use, and instructed in the proper
use and maintenance of them. This module will explain about fastener and fastening tools, gripping and clamping
tools, impact tools, and cutting tools, for a little about marking, measuring and gauging tools. More about marking,
measuring and gauging tools will provide in next module. And for portable power tools will introduce and explain in
use power tools module.
More explain about classification in section two.
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18.1A Use hand tools
Topic One – Introduction
Safety
Always use proper personal protective equipment (PPE) when do our job.
Give attention to care in the use of hand tools. Hand tools can cause incidents when an incorrect, improvised or
defective tool is used. Also, when the correct tool is used carelessly, or not put away safely, injury may result.
 Make sure you select the proper type and size of tool for the job.
 Check the condition of any tools before use it.
 Do not use tools that are worn out or damaged.
 Maintain tools in good condition and remember that cutting tools need
to sharp to be safe.
 Make sure you use each tool in the correct manner.
 Replace tools on shadow boards or in their correct place when you
are not using them.
 Do not use hammer to assist the turning movement of a spanner.
 Do not extend spanners with a length of piping or other means to
increase leverage.
 Do not strike a hardened surface (ball race, etc.) with a hammer, as
one or both surfaces may chip and fly.
 Do not use spanners or any tools that coated with grease or oil.
 Do not carry screwdrivers, chisels or pointed tools in the pockets of
overalls, etc. They are dangerous in the event of the fall.
 Do not use spanner as a hammer.
Learn to use all the hand tools a correct and safe method for each tool is described in section two and three.
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