Handling toolsRemember the following points: Use tools correctly. Don’t overload a tool – it may cause

the tool to slip or break, resulting in damage and injury.

Inspect tools for deficiencies before you use them.

Keep tools clean and return them to their proper places.

Report any tools which show signs of wearing or breaking.

Properly dress chisels and punches which have curled-over (mushroomed) heads before using them to prevent the mushroomed edge breaking off when hammered.

Also attend to loose or cracked hammer handles before using them.

The tool should fit over the bolt head or nut with the minimum of free play.

As far as possible, ‘pull’ the spanner and don’t ‘push’ it.

When you have to push a spanner, do so with an open hand and push in the direction in which force is applied.

There are four types of spanner:

open-ended spanners

ring spanners

combination spanners

socket spanners.

A socket is used with various accessories such as:

a ratchet

a speed wrench or brace

various extensions

power bars

flexible joints

universal joints

Plier types include: combination pliers

to keep an object in position, to tighten something or to cut wire.

diagonal cutting pliers for cutting objects such as split pins or wire.

long-nose pliers Used in confined or unreachable spaces

circlip pliers outside circlip pliers and the inside circlip

pliers are used to remove circlips

waterpump pliers used for larger objects as they can be

extended

vice grip pliers. use them to clamp metal objects

We use screwdrivers to loosen or tighten machine screws and self-tapping screws.

Flat tip screwdriver used for general work.

Phillips screwdriver for the cross-headed screws

Used to check for squareness The stock is made of steel The blade is hardened and tempered

A steel tape is used to measure long lengths.

The tape is made of spring steel, cast steel or stainless steel

Tapes vary in length from 2 m up to 50 m and sometimes longer.

Measure lengths up to 300 mm Made of spring steel, cast steel

or stainless steel Do not knock the edges

Used to draw lines on materials Made of tool steel When a scriber line is not clearly

visible, it should be prepared with a cover layer such as an engineer’s blue spray.

Centre punch Used to enlarge the pop mark on a

surface where a hole has to be drilled The enlarged pop mark acts as a guide

for the drill Made of tool steel and the included

angle should be 90°.

Prick punch Used to mark or ‘pop’ scribed lines to

make them more prominent Half of the pop mark will remain,

indicating the position of the line, after objects are machined

Made of tool steel. The included angle should be 60°

Ball pein hammers

Hammer heads made of carbon steel or cast steel that

contains approximately 0,6% carbon classified according to the mass of the

head which varies from 250g to 1 kg face and pein are hardened and

tempered The striking face is used for driving blows

and the pein for riveting.

The cheek of a hammer is left untempered to maintain its tenacity.

If hardened, it could easily crack or break

TENACITY - not easily disconnected: holding together tightly or fused solidly

The hole or eye, in which the shaft fits, is tapered

This allows the end of the shaft to expand when a wedge is driven into the shaft

The wedge is made of steel or hard wood The shaft must be well-seasoned,

straight-grained wood without knots Ash or hickory wood is normally used

because of its ability to absorb shock

Head of these hammers is made of copper, lead, leather, rubber or plastic

Most of these heads are replaceable. Used to knock on finished surfaces

which should not be damaged

A hacksaw is used to cut metals and composites

Hacksaw frame :- Fixed or Adjustable type Hacksaw handle :- straight or pistol-grip

type Hacksaw blade-holder

threaded square section with wingnut to tighten the blade

blades fits over other end which has a peg, Hacksaw blade High speed steel blades are used on harder

metals Medium carbon steel blades are used on softer

metals such as copper

Temper the degree of hardness of a metal

Set to become bent from strain

Tooth size Expressed in the term ‘teeth per 25 mm’

Length measured between the outside edges of

the holes in the blade

TEMPER All hard

The entire blade is hardened for accurate work relatively brittle and expensive

Tooth-hardened Only the teeth are tempered and the blade is

flexible for workers who must still develop their skills.

Prevents binding in the saw-cut and the blade breaking

Teeth are set to saw a wider cut than the blade thickness

Alternately:- set slightly outward to the left and right

Wavy Pattern:- groups of teeth are set to the left and right

:- used on blades with fine teeth.

The frame must be in a good condition The correct blade must be chosen. Fit blade with the teeth pointing away from

handle. Ensure that the tension of the blade is correct. Clamp the work piece firmly and start cutting

on a flat surface. Saw with long even strokes and apply slight

pressure. Use the full length of the saw. The number of strokes should not exceed 60

per minute

Skew sawing motion Incorrect tension Cutting at a sharp angle Metal not firmly clamped Blade binding in the cut.

A cutting tool that has surfaces with sharp tooth-edges

Use a file to reduce objects to a particular size or shape

Made of cast steel the blade is left very hard while the tang is left soft to prevent it from

snapping under the pressure of filing

Files are graded and classified according to their :- Length

end of the shoulder to the other end.(blade) Section

Half-round files, Three-square files & Square files etc.

Cut Single-cut files, Double-cut files & Rasps

and degree of coarseness rough, bastard, second-cut and smooth files

Single-cut files Teeth are cut parallel to one another,

across its surface, Angle of cut is approximately 65° to the

axis of the file. It is recommended for working on soft

metal such as copper, lead and brass.

Double-cut files Has a second series of parallel teeth cut in the

opposite direction to the first set of teeth. The first set is cut at about 45° and the other

set is cut at between 70° and 80° to the axis of the file.

These files are used for general work. Rasps

The teeth on a rasp are course and large. Rasps are used for filing very soft materials

such as wood and leather.

Flat files rectangular and its width is parallel for

about two-thirds of its length; from there, the file tapers in width and thickness.

These files are always double-cut on the surface and single-cut on the edge

And are used for general purpose

Square files Taper for the last third of their length and are

double-cut on all faces. They are used for filing corners, slots and

square holes. Round files

Taper like the square file and are mostly single-cut for lengths of up to 150 mm. (Rough and bastard types are used for longer lengths and are double-cut.)

They are used for opening out holes and for filing round corners.

Half-round files Usually double-cut on the flat face, and single-cut

on the curved surface. This section is not quite semi-circular, and it

tapers the last third of its length, both in width and thickness.

They are used for filing corners less than 90° and concave surfaces.

Three-square files Usually double-cut, and taper to a point. They have three 60° corners and are used to

sharpen saw-teeth and to file corners less than 90°.

Knife-edge files Two faces are double-cut while their edges are

single-cut. Used for filing or cleaning out sharp corners.

File handles Made of wood (or plastic) with a steel ferrule

at the ends. Different sizes are available to suit the size of

the file. Always ensure that the file tang fits tightly

into the handle, as a file with a loose handle is liable to cause serious injury.

A chisel is used for removing metal that cannot be removed conveniently by a machine.

The length of the chisel, its selection and shape depend on the particular work for which it’s needed.

Chisel materials Chisels are made of hardened and tempered

cast steel, and are of octagonal section (from an eight-sided steel bar).

Cutting angles Ground on the emery wheel, the cutting angle

being determined by the metal to be chipped. Harder the metal = greater the cutting angle. The following angles are recommended for

chipping various metals: aluminium: 35° copper and brass: 40° wrought iron and mild steel: 50° cast iron: 60° cast steel: 70°.

Cutting angles Take care not to over-heat a chisel while it

is being ground as temper will be taken out, and the degree of hardness reduced.

Flat chisels The flat chisel (cold chisel) is most

commonly used for general dressing, chipping and cutting.

The cutting edge should be slightly convex as this prevents damage to the outer corners and gives a longer life to the chisel.

Crosscut chisels A crosscut chisel is used for cutting grooves,

slots, recesses and keyways Round nose chisels

The straight type is used for drawing over drill centres, in drilling and cutting oil grooves along flat or convex surfaces such as slides, bearings, etc.

The curved type is used for cutting oil grooves along the curved surface of a bearing.

Diamond point chisels A diamond point chisel is used mainly for

finishing off and cleaning out corners, and for cutting ‘V’ grooves.

When chipping, watch the cutting edge and not the head of the chisel.

Place a suitable guard in front of the work to protect others from injury.

Wear goggles to protect your eyes. Dress the head of the chisel when it

becomes mushroomed or ragged as the chips that may break off are liable to cause serious injury.

Assessments for this chapter are found on pages :-

36 to 41, 43, 45 & 47 Please prepare for a class test.