SAFETY RULES & UNSAFE PRACTICES

Remember that “accidents do not occur, they are caused”. With this in mind, strictly follow the
general safety rules given below and safe practices indicated in brief under each section.

1. Safety first, work next.

2. Know your job and follow instructions.

3. Avoid wearing clothing that might catch, moving or rotating parts. Long sleeves of
shirts, long hair, neck tie and jewellery are definite hazards in the shop.

4. Wear safety shoes. Do not wear canvas shoes; they give no resistance to hard
objects dropped on the feet.
5. Keep the area around machine or work clean.
6. Keep away from revolving work.
7. Be sure that all gaurds are in place.
8. One person only should operate the machine controls.
9. Use tools correctly and do not use them if they are not in proper working condition.

10. Wear safety goggles when working in areas, where sparks or chips of metal are
flying.

11. Get to know who in-charge of first aid is and where boxes are placed and where the
first aid can be found in case of emergency.
 CONTENTS

1. FITTING 04-16

2. CARPENTRY 17-27

3. TIN SMITHY 29- 37

4. HOUSE WIRING 38-47

5. BLACK SMITHY 48-51

6. FOUNDRY 52-59
 1. FITTING

Introduction

Machine tools are capable of producing work at a faster rate, but, there are occasions when
components are processed at the bench. Sometimes, it becomes necessary to replace or repair
component which must be fit accurately with another component on reassembly. This involves a
certain amount of hand fitting. The assembly of machine tools, jigs, gauges, etc, involves certain
amount of bench work. The accuracy of work done depends upon the experience and skill of the
fitter.

The term ‘bench work’ refers to the production of components by hand on the bench, where as
fitting deals which the assembly of mating parts, through removal of metal, to obtain the required
fit.

Both the bench work and fitting requires the use of number of simple hand tools and
considerable manual efforts. The operations in the above works consist of filing, chipping,
scraping, sawing drilling, and tapping.

Holding Tools:

Bench Vice

The bench vice is a work holding device. It is the most commonly used vice in a fitting shop.
The bench vice is shown in figure below.

It is fixed to the bench with bolts and nuts. The vice body consists of two main parts, fixed jaw
and movable jaw. When the vice handle is turned in a clockwise direction, the sliding jaw forces
the work against the fixed jaw. Jaw plates are made of hardened steel. Serrations on the jaws
ensure a good grip. Jaw caps made of soft material are used to protect finished surfaces, gripped
in the vice. The size of the vice is specified by the length of the jaws.

Fig: Bench Vice

The vice body is made of cast iron which is strong in compression, weak in tension and so
fractures under shocks and therefore should never be hammered.
V‐block is rectangular or square block with a V‐groove on one or both sides opposite to each other.
0
The angle of the ‘V’ is usually 90 . V‐block with a clamp is used to hold cylindrical work
securely, during layout of measurement, for measuring operations or for drilling for this the bar
is faced longitudinally in the V‐Groove and the screw of V‐clamp is tightened. This grip the rod
is firm with its axis parallel to the axis of the v‐groove.

Fig: V‐ Block Fig: C ‐ Clamp

C‐ Clamp

This is used to hold work against an angle plate or v‐block or any other surface, when gripping is
require Its fixed jaw is shaped like English alphabet ‘C’ and the movable jaw is round in shape
and directly fitted to the threaded screw at the end .The working principle of this clamp is the
same as that of the bench vice.

Marking and Measuring Tools:

Surface Plate

The surface plate is machined to fine limits and is used for testing the flatness of the work piece.
It is also used for marking out small box and is more precious than the marking table. The degree
of the finished depends upon whether it is designed for bench work in a fitting shop or for using
in an inspection room; the surface plate is made of Cast Iron, hardened Steel or Granite stone. It
is specified by length, width, height and grade. Handles are provided on two opposite sides, to
carry it while shifting from one place to another (refer figure in next page).

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It is measuring and marking tool for 90 angle .In practice, it is used for checking the squareness
of many types of small works when extreme accuracy is not required .The blade of the Try
square is made of hardened steel and the stock of cast Iron or steel. The size of the Try square is
specified by the length of the blade.

Scriber
A Scriber is a slender steel tool, used to scribe or mark lines on metal work pieces. It is made of
o
hardened and tempered High Carbon Steel. The Tip of the scriber is generally ground at 12 to
o
15 .

It is generally available in lengths, ranging from 125mm to 250mm .It has two pointed ends the
bent end is used for marking lines where the straight end cannot real.

Fig: Try Square Fig: Scriber

Odd Leg Caliper

This is also called ‘Jenny Caliper’ or Hermaphrodite. This is used for marking parallel
liners from a finished edge and also for locating the center of round bars; it has one leg pointed
like a divider and the other leg bent like a caliper. It is specified by the length of the leg up to the
hinge point.
Divider
It is basically similar to the calipers except that its legs are kept straight and pointed at the
measuring edge. This is used for marking circles, arcs laying out perpendicular lines, by setting
lines. It is made of case hardened mild steel or hardened and tempered low carbon steel. Its size
is specified by the length of the leg.

Fig: Odd Leg Caliper and Divider

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Trammel is used for drawing large circles or arcs.
Punches
These are used for making indentations on the scribed lines, to make them visible clearly. These
are made of high carbon steel. A punch is specified by its length and diameter (say as 150’
12.5mm). It consists of a cylindrical knurled body, which is plain for some length at the top of it.
At the other end, it is ground to a point. The tapered point of the punch is hardened over a length
of 20 to 30mm.

Dot Punch is used to lightly indent along the layout lines, to locate center of holes and to
provide a small center mark for divider point, etc. for this purpose, the punch is ground to a
conical point having 60° included angle.

Center Punch is similar to the dot punch, except that it is ground to a conical point having 90°
included angle. It is used to mark the location of the holes to be drilled.

Fig: Punches
Calipers:
They are indirect measuring tools used to measure or transfer linear dimensions. These are used
with the help of a steel Rule to check inside and outside measurements. These are made of Case
hardened mild steel or hardened and tempered low carbon steel. While using, but the legs of the
caliper are set against the surface of the work, whether inside or outside and the distance between
the legs is measured with the help of a scale and the same can be transferred to another desired
place. These are specified by the length of the leg. In the case of outside caliper, the legs are bent
inwards and in the case of inside caliper, the legs bent outward.

Fig: Calipers
Cutting Tools:

Hack Saw
The Hack Saw is used for cutting metal by hand. It consists of a frame, which holds a thin blade,

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firmly in position. Hacksaw blade is specified by the number of teeth for centimeter. Hacksaw
blades have a number of teeth ranging from 5 to 15 per centimeter (cm). Blades having lesser
number of teeth per cm are used for cutting soft materials like aluminum, brass and bronze.
Blades having larger number of teeth per centimeter are used for cutting hard materials like steel
and cast Iron.

Fig: Hacksaw Frame with Blade

Hacksaw blades are classified as (i) All hard and (ii) flexible type. The all hard blades are made
of H.S.S, hardened and tempered throughout to retain their cutting edges longer. These are used
to cut hard metals. These blades are hard and brittle and can break easily by twisting and forcing
them into the work while sawing. Flexible blades are made of H.S.S or low alloy steel but only
the teeth are hardened and the rest of the blade is soft and flexible. These are suitable for use by
un‐skilled or semi‐skilled persons.

The teeth of the hacksaw blade are staggered, as shown in figure and known as a ‘set of teeth’.
These make slots wider than the blade thickness, preventing the blade from jamming.

Chisels

Chisels are used for removing surplus metal or for cutting thin sheets. These tools are made from
0.9% to 1.0% carbon steel of octagonal or hexagonal section. Chisels are annealed, hardened and
tempered to produce a tough shank and hard cutting edge. Annealing relieves the internal
stresses in a metal. The cutting angle of the chisel for general purpose is about 60°.

Fig: Flat Chisel

Twist Drill

Twist drills are used for making holes. These are made of High speed steel. Both straight and
taper shank twist drills are used. The parallel shank twist drill can be held in an ordinary self –

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centering drill check. The tapper shank twist drill fits into a corresponding tapered bore provided
in the drilling machine spindle (see figure in next page).

Taps and Tap Wrenches

A tap is a hardened and steel tool, used for cutting internal thread in a drill hole. Hand Taps are
usually supplied in sets of three in each diameter and thread size. Each set consists of a tapper
tap, intermediate tap and plug or bottoming tap. Taps are made of high carbon steel or high speed
steel (see figure in next page).
Bench Drilling Machine
Holes are drilled for fastening parts with rivets, bolts or for producing internal thread. Bench
drilling machine is the most versatile machine used in a fitting shop for the purpose. Twist drills,
made of tool steel or high speed steel are used with the drilling machine for drilling holes.

Following are the stages in drilling work

1. Select the correct size drills, put it into the check and lock it firmly
2. Adjust the speed of the machine to suit the work by changing the belt on the pulleys. Use
high speed for small drills and soft materials and low speed for large diameter drills and hard
materials.
3. Layout of the location of the pole and mark it with a center punch.
4. Hold the work firmly in the vice on the machine table and clamp it directly on to the machine
table.
5. Put on the power, locate the punch mark and apply slight pressure with the Feed Handle.

Fig: Bench Drill

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Finishing Tools:

Reamers
Reaming is an operation of sizing and finishing a drilled hole, with the help of a cutting tool
called reamer having a number of cutting edges. For this, a hole is first drilled, the size of which
is slightly smaller than the finished size and then a hand reamer or machine reamer is used for
finishing the hole to the correct size.

Hand Reamer is made of High Carbon Steel and has left‐hand spiral flutes so that, it is prevented
from screwing into the whole during operation. The Shank end of the reamer is made straight so
that it can be held in a tap wrench. It is operated by hand, with a tap wrench fitted on the square
end of the reamer and with the work piece held in the vice. The body of the reamer is given a
slight tapper at its working end, for its easy entry into the whole during operation, it is rotated
only in clock wise direction and also while removing it from the whole.

Fig: Reamers

Files

Filing is one of the methods of removing small amounts of material from the surface of a metal
part. A file is hardened steel too, having small parallel rows of cutting edges or teeth on its
surfaces.

On the faces, the teeth are usually diagonal to the edge. One end of the file is shaped to fit into a
wooden handle. The figure shows various parts of a hand file. The hand file is parallel in width
and tapering slightly in thickness, towards the tip. It is provided with double cut teeth. On the
faces, single cut on one edge and no teeth on the other edge, which is known as a safe edge.

Fig: Parts of a Hand File

Files are classified according to their shape, cutting teeth and pitch or grade of the teeth.
The figure shows the various types of files based on their shape.

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 Fig: Single and Double Cut Files

Miscellaneous Tools:

Ball‐ Peen Hammer

Ball‐ Peen Hammers are named, depending upon their shape and material and specified by their
weight. A ball peen hammer has a flat face which is used for general work and a ball end,
particularly used for riveting.

Cross‐Peen Hammer

It is similar to ball peen hammer, except the shape of the peen. This is used for chipping,
riveting, bending and stretching metals and hammering inside the curves and shoulders.

Fig: Cross Peen Hammer Fig: Straight Peen Hammer

Straight‐Peen Hammer

This is similar to cross peen hammer, but its peen is in‐line with the hammer handle. It is
used for swaging, riveting in restricted places and stretching metals.

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Viva Questions

Question: Define the terms: Fitting and Bench work.

Question: Name the material with which a vice body is normally made of. What is
the characteristic of this material?
Question: What for a C-clamp is used?
Question: Classify hacksaw blades.
Question: Differentiate between ‘Single cut’ and ‘Double cut’ files.
Question: Differentiate between ‘Cross filing’ and ‘Draw filing’. Question:
Name the different types of hammers used in fitting work.
Question: Differentiate between cross-peen hammer and straight-peen hammer.
Question: What is meant by pinning of files?
Question: With what the size of a spanner is denoted?

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2.CARPENTRY
Introduction
Carpentry may be defined as the process of making wooden components. It starts from a
marketable form of wood and ends with finished products. It deals with the building work,
furniture, cabinet making. Etc. joinery, i.e., preparation of joints is one of the important
operations in all woodworks. It deals with the specific work of carpenter like making
different types of joints to form a finished product.

Timber:

Timber is the name given to the wood obtained from well grown trees. The trees are cut, sawn
into various sizes to suit building purposes.

The word, ‘grain’, as applied to wood, refers to the appearance or pattern of the wood on the cut
surfaces. The grain of the wood is a fibrous structure and to make it strong, the timber must be so
cut, that the grains run parallel to the length.

Timber Sizes

Timber sold in the market is in various sizes and shapes. The following are the common shapes
and sizes.
d.

a. Log The trunk of the tree which is free from branches.

‐

b. Balk The log, sawn to have roughly square cross section.

‐

c. Post
‐

to 300mm.
A timber piece, round or square in cross section, having its diameter or side from
175 ‐

Plank A sawn timber piece, with more than 275 mm in width, 50 to 150 mm in
thickness and 2.5 to 6.5 meters in length.
e. Board ‐ A sawn timber piece, below 175 mm in width and 30 to 50 mm in thickness.
f. Reapers‐ Sawn timber pieces of assorted and non‐standard sizes, which do not confirm to
the above shapes and sizes.

Classification of Timber

Wood suitable for construction and other engineering purposes is called timber. Woods in
general are divided into two broad categories: Soft woods and Hard woods.

Soft woods are obtained from conifers, kair, deodar, chir, walnut and seemal. Woods obtained
from teak, sal, oak, shisham, beach, ash mango, neem and babul are known as hard wood, but it
is highly durable.

Another classification of woods is based on the name of the trees like teak, babul, shisham,
neem, kair, chir, etc.

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Seasoning of Wood

A newly felled tree contains considerable moisture content. If this is not removed, the timber is
likely to wrap, shrink, crack or decay. Seasoning is the art of extracting the moisture content
under controlled conditions, at a uniform rate, from all the parts of the timber. Only seasoned
wood should be used for all carpentry works. Seasoning makes the wood resilient and lighter.
Further, it ensures that the wood will not distort after it is made into an object.

Characteristics of Good Timber

The good timber must possess the following characteristics

a. It should have minimum moisture content, i.e., the timber should be well seasoned.
b. The grains of wood should be straight and long.
c. It must retain its straightness after seasoning.
d. It should produce near metallic sound on hammering.
e. It should be free from knots or cracks.
f. It should be of uniform color, throughout the part of the wood.
g. It should respond well to the finishing and polishing operations.
h. During driving the nails and screw, it should not split easily.
Marking and Measuring Tools:
Accurate marking and measurement is very essential in carpentry work, to produce parts to exact
size. To transfer dimensions onto the work; the following are the marking and measuring tools
that are required in a carpentry shop.

Steel Rule and Steel Tape

Steel rule is a simple measuring instrument consisting of a long, thin metal strip with a marked scale
of unit divisions. It is an important tool for linear measurement. Steel tape is used for large
measurements, such as marking on boards and checking the overall dimensions of the work.

Fig: Steel Rule and Steel Tape

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Marking Gauge

It is a tool used to mark lines parallel to the edge of a wooden piece. It consists of a square
wooden stem with a sliding wooden stock (head) on it. On the stem is fitted a marking pin, made
of steel. The stock is set at any desired distance from the marking point and fixed in position by a
screw. It must be ensured that the marking pin projects through the stem, about 3 mm and the
end are sharp enough to make a very fine line. A mortise gauge consists of two pins. In this, it
is possible to adjust the distance between the pins, to draw two parallel lines on the stock.

Marking gauge Mortise gauge

Fig: Marking Gauges

Try ‐ Square

It is used for marking and testing the squareness and straightness of planed surfaces. It consists
of a steel blade, fitted in a cast iron stock. It is also used for checking the planed surfaces for
flatness. Its size varies from 150 to 300 mm, according to the length of the blade. It is less
accurate when compared to the try‐square used in the fitting shop.

Fig: Try Square

Compass and Divider
Compass and divider, are used for marking arcs and circles on the planed surfaces of the wood
(refer fig in next page).

Scriber or Marking Knife

It is used for marking on timber. It is made of steel having one end pointed and the other end
formed into a sharp cutting edge (refer Fig. in next page).

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Bevel Square
It is used for laying‐out and checking angles. The blade of the bevel is adjustable and may be
held in place by a thumb screw. After it is set to the desired angle, it can be used in much the
same way as a try‐square. A good way to set it to the required angle is to mark the angle on a
surface and then adjust the blade to fit the angle

Fig: Compass and Divider Fig: Scriber and Bevel Square

Holding Tools:

Carpenter's Vice

It is used as a work holding device in a carpenter shop. Its one jaw is fixed to the side of the table
while the other is movable by means of a screw and a handle. The Carpenter's vice jaws are lined
with hard wooden' faces

‐C
Fig: Carpenters Vice Fig: C lamp
C‐Clamp
It is used for holding small works (see figure above)
Bar Cramp
It is made of steel bar of T‐section, with malleable iron fittings and a steel screw. It is used for
holding wide works such as frames or tops.
Planing Tools:

Planing is the operation used to produce flat surfaces on wood. A plane is a hand tool used for
this purpose. The cutting blade used in a plane is very similar to a chisel. The blade of a plane is
fitted in a wooden or metallic block, at an angle.

Types of Planes:

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Jack Plane

It is the most commonly used general purpose plane. It is about 35 cm long. The cutting iron
(blade) should have a cutting edge of slight curvature. It is used for quick removal of material on
rough work and is also used in oblique planning.

Smoothing Plane

It is used for finishing work and hence, the blade should have a straight cutting edge. It is about
20 to 25 cm long. Being short, it can follow even the slight depressions in the stock, better than
the jack plane. It is used after using the jack plane.

Rebate Plane

It is used for making a rebate. A rebate is a recess along the edge of a piece of wood, which
is generally used for positioning glass in frames and doors.

Plough Plane

It is used to cut grooves, which are used to fix panels in a door. The following figure shows the
various types of planes mentioned above.

Cutting Tools:
Saws
A saw is used to cut wood into pieces. There are different types of saws, designed to
suit different purposes. A saw is specified by the length of its toothed edge.
Types of Saws:
Cross‐Cut Saw or Hand Saw
It is used to cut across the grains of the stock. The teeth are so set that the saw kerf will be wider
than the blade thickness. This allows the blade to move freely in the cut, without sticking
Rip Saw

It is used for cutting the stock along the grains. The cutting edge of this saw makes a steeper
angle, i.e., about 60° whereas that of crosscut saw makes an angle of 45° with the surface of the

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stock.
Tenon Saw
It is used for cutting the stock either along or across the grains. It is used for cutting tenons and
in fine cabinet work. However, it is used for small and thin cuts. The blade of this saw is very
thin and so it is stiffened with a thick back steel strip. Hence, this is sometimes called as back‐
saw. In this, the teeth are shaped like those of cross‐cut saw.
Compass Saw
It has a narrow, longer and stronger tapering blade, which is used for heavy works . It is mostly
used in radius cutting. The blade of this saw is fitted with an open type wooden handle.

Fig: Types of Saws

Chisels:

Chisels are used for cutting and shaping wood accurately. Wood chisels are made in various
blade widths, ranging from 3 to 50 mm. They are also made in different blade lengths. Most of
the wood chisels are made into tang type, having a steel shank which fits inside the handle.
These are made of forged steel or tool steel blades.

Fig: Types of Chisels

Types of Chisels:

Firmer Chisel
The word 'firmer' means 'stronger' and hence firmer chisel is stronger than other chisels.
It is a general purpose chisel and is used either by hand pressure or by a mallet. The blade of a
firmer chisel is flat, as shown in figure.

Dovetail Chisel
It has a blade with a beveled back, as shown in Figure, due to which it can enter sharp comers
for finishing, as in dovetail joints.

Mortise Chisel
It is used for cutting mortises and chipping inside holes, etc. The cross‐section of the
mortise chisel is proportioned to withstand heavy blows during mortising. Further, the cross‐
section is made stronger near the shank..

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Viva Questions

Question: Name the commonly available shapes of timber in the market.

Question: What is the sequence of operations in carpentry?
Question: What is the difference between marking gauge and marking knife?
Question: What is the difference C-clamp and bar cramp?
Question: What for a plane is used in a carpentry shop?
Question: Classify the planning tools.
Question: Classify the chisels and their applications.
Question: Name the tools used for pulling nails.
Question: Name the various joinery materials used in carpentry.
Question: Name the various types of joints.
Question: Name some holding, marking, measuring, cutting, planning and finishing tools.

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INTRODUCTION

3.TIN SMITHY:

Tin smithy deals with the production of components in a wide variety of shapes and sizes
from a sheet of metal with the aid hand or machines. For example many Engineering and house
hold articles such as hoppers, guards covers, boxes and cans, funnels and ducts etc. are made
from a flat sheet of metal.

Sheet Metals Used in Metal Work:

A wide variety of metals, in the form of sheet are used in sheet metal workshop. The most
commonly used are explained below.

Galvanized Iron (G.I.) Sheet

It is a sheet of soft steel coated with zinc. I sheet is one of the least expensive metals used in
sheet metal shop. It is used for making pans, buckets, gutters, tanks, boxes etc. Generally GI
products are very suitable for corrosive environment because zinc coating protects the iron form
corrosion.

Copper

It has reddish color and is used for water pipes, roofing, gutters and other parts of the building.
Copper products are used where thermal resistance is the criterion along with corrosion
resistance. But copper is somewhat expensive.

Tin Plate

Tin plate is the iron or steel coated with pure tin. It has bright silvery appearance and is used for
containers, dairy equipments, furnace fittings, cans, trays and pans.

Stainless Steel

The 18-8 type steel is used in sheet metal work from the available different type of stainless
steel. The products like food containers, dairy equipments and kitchen wares are prepare from
18-8 steel.

Black Iron

It is an uncoated sheet of metal with bluish appearance. The black iron sheet is used for the
products, which are having no restrictions on painting after its preparation.

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Aluminium

It is an uncoated sheet of metal with bluish appearance. The black iron sheet is used for the
products, which are having no restrictions on painting after its preparation.

Tools and Equipments:

Most of the tools that are used in fitting are also used in sheet metal work. The additional tools
specially used in sheet metal work are described below.

Steel Rule

Steel rule is a simple measuring instrument consisting of a long, thin metal strip with a marked
scale of unit divisions. It is an important tool for linear measurement.

Fig: Steel Rule

Try Square

It is measuring and marking tool for 900 angle .In practice, it is used for checking the squareness
of many types of small works when extreme accuracy is not required .The blade of the Try
square is made of hardened steel and the stock of cast Iron or steel. The size of the Try square is
specified by the length of the blade.

Fig: Try Square

Compass and Divider

Compass and divider, are used for marking arcs and circles on the planed surfaces of the
GI sheet.
Snips:
Snips are hand shears varying in length from 200mm to 600mm. The 250 mm length is
the commonly used one.

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Types of Snips:

Straight snip

It has a straight blade and is used for cutting along straight lines and for trimming the edges. The
straight snip and its usage is shown in figure below:

Fig: Straight Snip

Bent or Curved Snip

It is having curved blade and is used for cutting circles and irregular shapes. It is also used for
trimming the cylindrical edges. The curved snip and its usage is shown in figure below:

Fig: Bent or Curved Snip

Double Snip

Double shears are used for cutting thin cylinders, stove pipes and for cutting holes and light
gauge metals. The double cut snip is shown in figure below:

Fig: Double Snip

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Bench Shear

In this type of hand cutting machine, the sheet is cut by shearing action. The force is applied
through compound lever. The machine is able to cut the sheet metal upto 2 mm thick.

The bench shear also consists of chopping hole in the chopping blade which can shear a mild
steel rod upto 10 mm diameter. The below figure represents the schematic diagram of bench
shear.

Fig: Bench Shear

Stakes:
Stakes are supporting tools used in sheet metal work. These are used to form, seam, bend or rivet
the sheet metal objects. Stakes are made of wrought iron, faced with steel. Its working face well
machined and polished to prevent harmful effect to sheet while doing the hammering process.
Types of Stakes:

Funnel Stake
It is used for forming conical shapes and for making wire rings. The below figure shows the line
diagram of funnel stake:
Half Moon Stake

It is used for folding edges of cylindrical shaped articles. The half moon stake is shown in
figure below:

Beak Horn Stake

It is used for shaping round, square surfaces, bending edges, and making corners. The beak
horn stake is shown in figure below:

It is used for forming or seaming funnels. The below figure represents the blow horn stake:

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Conductor Stake

It is used for forming pipes and cylindrical pieces. The conductor stake is shown in figure below:

Hatchet Stake

It has a horizontal sharp straight edge and is used for making straight, sharp bends and
folding edges. The schematic representation of hatchet stake is shown in figure below:

Fig: Hatchet Stake

Fig: Setting Hammer
Hammers and Mallets:

Hammers and mallets are used to apply moderate forces gently in the processes accompanied in
tinsmithy such as forming and bending.
Types of Hammers and Mallets:

Setting Hammer

It has a square, flat face and its peen is tapered on one side. It is used for setting down the
edges for making a double seam. The below figure represents the setting hammer:
Riveting Hammer

It has a square slightly curved face and its peen is tapered. It is used for riveting. The riveting
hammer is represented in figure below:

Fig: Riveting Hammer

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Raising Hammer

It is used for making depressions on a flat sheet, and it is particularly adapted for making trays,
bowls, and similar objects. The sketch of raising hammer is shown in figure below:

Fig: Raising Hammer

Mallet:

It is generally made of wood or plastic. It is used whenever slight blows are required. Wooden
hammer (mallet) is most commonly used because it does not damage the work surface. The
simple mallet used in tinsmithy is shown in figure below:

Fig: Mallet
Miscellaneous Tools:

Hand Groover

It is used for grooving a seam by a hand. It has a recessed end to fit over the block of seam. The
shape of hand groover and usage is shown in figure below.

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INTRODUCTION

4.HOUSE WIRING

Power is supplied to domestic installations through a phase and a neutral, forming a

single phase A.C.230V, two-wire system. For industrial establishments, power is supplied
through three-phase four wire system, to give 440 V. Figure 3.1 shows the power tapping for
domestic and industrial purposes. The neutral is earthed at the distribution sub-station of the
supply.

When supplied to domestic utilities, power is fed to a kilowatt meter and then to a distribution
panel. The panel distributes power along several circuits. It also protects these circuits from
overload by safety devices like fuses or circuit breakers. The panel also serves as a main switch.

As a safety practice, all single-phase devices such as switches, fuses, etc., are connected to the
live conductor. All electrical conductors and cables are color coded and must be correctly
connected-up. Electrical wiring is defined as a system of electric conductors, components and
apparatus for conveying electric power from the source to the point of use. The wiring system
must be designed to provide a constant voltage to the load.

Fig: 3 Phase – 4 Wire Supply

Elements of House Wiring:

Fuses and Circuit Breakers

These are the devices designed to provide protection to a circuit against excess current. In old
type of distribution panels, open link fuses, plug or cartridge fuses were used. In newer panels,
circuit breakers are used. If something goes wrong with an appliance or supply, the

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line becomes over loaded or short-circuited. Then, either the fuse blows-out or circuit breaker
trips open, isolating that circuit or appliance. In such cases, the appliance must be checked for
defects or it must be ensured that there are not too many appliances in that particular circuit.

Figure below shows several forms of fuses that are in use. Open link fuses are not safe in
operation, even though they are cheaper and reliable. It consists of a thin strip of metal or wire.
Here, when the fuse blows-off due to heavy current in the circuit, the metal is spilled around. A
modified version of it consists of a porcelain fuse link, backing the wire safely.

Fig: Forms of Fuses

Through the plug fuse confines the molten metal thrown out while blowing, it is not very
accurate in operation. The length of the element also is very short. The cartridge fuse of non-
renewable type, enclose the fuse element in a fiber tube with a non-inflammable material. During
the blowing-off, the arc produced is chilled by the non-inflammable material. In case of a
renewable type, a cheap renewable fuse material is used in the cartridge.

The trouble with fuses is that they must be replaced once they burn away, whereas the circuit
breaker can be reset after the original condition is established. An electromagnetic circuit breaker
is shown in below figure. A set of switch contacts inside the circuit breaker is normally kept
closed by an armature. When too much current flows through the coil, the armature is attracted,
breaking the circuit. The circuit breaker may be reset by a toggle lever.

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Common House Wiring Connections:

One Lamp Controlled by a One Way Switch

Figure (a) below shows the wiring diagram for a lamp controlled by a one way switch. This is
the normal connection one comes across in house wiring. However, more than one lamp may be
connected either in series or parallel and controlled by a one way switch as shown in figures b &
c respectively.

Lamp with Independent Control from Two Places

It is sometimes desirable to control from two different places .one may come across this situation
with stair case, bed room, long corridors or hall containing two entrances, etc.this is achieved by
two way switches as shown in fig.d.

Two Lamps Connected in Series or Parallel by a One Way Switch

Two lamps may be connected by a one way switch in parallel for bright glow or in series for dull
glow .this is recommended when the intensity in the room as to be controlled (fig.e).

Tube Light Connection

Figure (f) shows a typical tube light connection. Tube lights are the commonly used light
sources for illumination in the houses, industries, commercial organizations, etc. A tube light
is a low power mercury discharge lamp with internal surface coated with suitable fluorescent
material. This lamp consist of a glass tube, provided at both ends with caps having two pins
and oxide coated tungsten filament. The tube contains argon or krypton gas to facilitate
starting with small quantity of mercury at low pressure.

Fig: Types of Connections

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Fluorescent material when subjected to electromagnetic radiations of a particular wave

length produced by the discharge till mercury vapor gets excited and in turn gives out radiations
at some other wave length which falls under visible spectrum. These secondary radiations from
fluorescent powder increase the efficiency of the lamp. Tube lights are generally made of 20
Watt or 40 Watt rating. In order to make a tube light self starting a starter and a choke are
connected in the circuit as shown in Fig. f.

When switch s1 is closed, full supply voltage induces across the starter electrodes P and Q which
are enclosed in a glass bulb, filled with organ gas. This voltage causes discharge in the organ gas,
resulting in the heating of the electrodes. Due to this heating, the electrode P which is made of
bimetallic strip, bends closes the contact of the starter. At this stage the choke, the filaments M1
and M2 of the tube T and the starter become connected in series across the supply; causing
current flow through the filaments M1 and M2 and heating them. Mean while, the argon gas
discharge in the starter tube disappears causing sudden break between electrodes P and Q. This
causes a high value of induced e.m.f in the choke. The induced e.m.f in the choke is applied
across the tube light electrodes M1 and M2 and is responsible for initiating a gaseous discharge.
Thus, the tube light starts giving light output. Once the discharge through the tube is established,
a much lower voltage than the supply voltage is required to maintain it. A reduction in voltage
available at the tube during running condition is achieved by having a voltage drop across the
choke.
Thecapacitor connected across the starter terminals P and Q is used to suppress the
electromagnetic waves generated at the gap due to sparking.

Note: the wattage of the tube, choke and starter should be the same.

Earthing

The definition of the term, “earthing or grounding” as it is otherwise called, refers to the
connection of the electrically equipment to the mass of the earth by a wire of negligible
resistance for the safety of the human body from shocks. The metallic covers of the machines,
the frames of the machines, sheathing of wiring, etc. are generally dead. Failure of insulation or
workmanship may make these alive. When this happens, a person touching the parts receives an
electric shock. To avoid this, the relevant parts are earthed. A good earthing system should have
a very low resistance and should be in a position to allow the leakage current through it. The
following are the methods of earthing:

(i) Earthing through a water main,

(ii) Plate earthing, and

(iii) Pipe earthing

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The following are the some of the items that need earthing: Metallic coverings containing
electric supply wire, switches, distribution fuse boards, ceiling fans, generator frames, stationary
and portable motors, metallic parts of transformer, refrigerators, energy meters, cooking oven,
electric heaters, etc.

Safe Practices

1. When closing the electric switch, always grasp the switch by the insulated handle

2. Do not run too many electrical items from one point

3. Use fuses in the circuit breakers of proper capacity, so as to interrupt the current before it
becomes dangerous

4. Disconnect the units to be repaired, free from power supply and make sure that they might not
be energized while the repair work continues

5. Do not pour water to put off fires in electric wires and electric equipment. You will be
subjected to electric shock or you will be electrocuted use sand to put off fires in electric items.

6. Whenever there is power failure put-off the power supply to all equipments in order to prevent
spontaneous recovery
7. Never remove a plug from an outlet by pulling the cord. Always pull by the plug.

8. Never work on electric wires when the power is on

9. Never work with bare feet

10. While testing, always keep one hand in your pocket. If the hands are in contact with a circuit,
a current will flow across your body and is more dangerous.

11. Electricity has no respect for ignorance. Do not apply voltage or turn-on any device until it
has been properly checked.

12. Check the earth connection before switching-on portable equipment

13. Before replacing the blown fuse, always switch-off the main switch

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Viva Questions

Question: Define electric wiring.

Question: Name the safety devices used to protect the electric circuits from overload.
Question: Differentiate between a fuse and a circuit breaker.
Question: What for a lamp holder is used in an electric circuit?
Question: Name the types of lamp holders available in the market.
Question: What for a ceiling rose is used?
Question: What is meant by an electric circuit? Question:
Name the three types of electrical circuits. Question: Name the
motor driven household appliances.
Question: What are the precautions to be taken, while connecting the wires with
electrical accessories?
Question: What is the difference emergency lamp and indicator lamp?
Question: Define the term earthing or grounding.
Question: Name the different methods of earthing.
Question: How much is the power supply required for house wiring?
Question: What is the purpose of choke in the fluorescent tube circuit?
Question: What is the purpose of starter in the fluorescent tube circuit?
Question: What is the reason of using parallel connections usually in the house wiring?
Question: What is the reason of getting less brilliancy of each bulb in series connections?

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7.FOUNDARY
Introduction

Foundry practice deals with the process of making castings in molds, formed in either sand or
some other material. The process involves the operations of pattern making, sand preparation,
molding, melting of metals, pouring in molds, cooling, shake-out, heat treatment, finishing, and
inspection.

Pattern

Pattern is the principal tool during the casting process. It may be defined as a model of anything,
so constructed that it may be used for forming an impression called would in damp sand or other
suitable material.

When this mold is filled with molten metal and the metal is allowed to solidify it forms a
reproduction of the pattern and is known as casting. The process of making pattern is known as
pattern making.

Mold

Mold is cavity formed by the pattern. It is similar in shape and size to that of the actual casting
plus some allowances for shrinkage, machining etc. Molds are classified as temporary and
permanent. Temporary molds are made of refractory sand and other binding materials and may
be produced either through hand molding or machine molding.

Molding Sand

Sand is the principal material used in foundry. The principal ingredients of molding sands are:
Silica sand, clay, moisture, and miscellaneous materials. Silica sand withstands very high
temperatures and doesn’t react with the molten metal.

Clay imparts the necessary bonding strength to the molding sand.

Moisture in requisite amount furnishes the bonding action of clay.

Miscellaneous materials that are formed in addition to silica and clay penetrates the mixture and
forms a microfilm which coats the surface flake shaped clay particles.

Natural molding sand is available in river beds or dug from pits. They possess an appreciable
amount of clay and are used as received with addition of water.

Synthetic sands are prepared by adding clay, water and other materials to silica sand so that
desired strength and bonding properties are achieved which are not possessed by natural sands.

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Properties of Molding Sand:

The essential requirement of good molding sand is that it should produce sound castings which
are free from defects. For producing sound castings, molding sand or mold should possess the
following properties; to quote a few:

Porosity or Permeability

When molten metal is poured into a mold, gases and steam are passed through it. If they are not
removed, casting defects such as blow holes will be formed.

Flowability

Flowability of molding sand refers to its ability to its ability, under externally applied forces
(ramming), into deeper sections of the pattern and uniformly fill the flask. Flowability increases
as clay and water content increase.

Collapsibility

Collapsibility is the property of sand that permits it to collapse (break) easily during its knockout
from the castings. This property is particularly important for cores. This property depends on
amount of the sand, clay and type of binder used.

Adhesiveness

Adhesiveness is the ability of a molding sand to stick on the surface of molding boxes. It is due
to this property that the sand mass can be successfully held in a molding box and it does not fall
out of the box when it is removed.

Cohesiveness or Strength

This is the ability of sand particles to stick together. Insufficient strength may lead to a collapse
in the mold or its partial destruction during conveying, turning over or closing.

Refractoriness

The sand must be capable of withstanding the high temperature of the molten metal without
fusing.

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Types of Molding Sand:

Molding sands are classified according to their use into a number of varieties. These are
described as follows:

Green Sand

It is a mixture of silica sand with 18 to 30 % clay having a total water of 6 to 8 %.

Dry Sand

Green sand that has been dried or baked after the mold is made is called dry sand.

Loam Sand

Loam sand is high in clay, as much as 50 %.

Facing Sand

Facing sand forms the face of the mold. It is used directly next to the surface of the pattern and it
comes into contact with the molten metal when the mold is poured. It is made of silica sand and
clay, without the addition of used sand.

Baking Sand

Baking sand or floor sand is used to backup the facing sand and fill the whole volume of the
flask. Old repeatedly used molding sand is mainly employed for this purpose. The baking sand is
sometimes called black sand because of the fact that old, repeatedly used molding sand is black
in color due to the addition of coal dust and burning on coming in contact with molten metal.

Parting Sand

Parting sand is used to keep the green sand from sticking to the pattern and also to allow the sand
on the parting surface of the cope and drag to separate without clinging. This is clean clay free
silica sand which serves the same purpose as parting dust.

Core Sand

The sand used for making cores is called as core sand and sometimes it is called as oil sand. This
is silica sand mixed with core oil which is composed of linseed oil. Resin light mineral oil and
other binding materials.

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Pattern Materials:

The selection of pattern materials depends primarily on the following factors.

1. Service requirement, e.g. quantity, quality, and intricacy of casting i.e. minimum
thickness, desired degree of accuracy, and finish required
2. Type of production of castings and the type of molding process
3. Possibility of design changes
4. Number of castings to be produced, i.e. possibility of repeat orders

To be good of its kind, pattern material should be:

a. Easily worked, shaped, and joined

b. Light in weight
c. Strong, hard, and durable, so that it may be resistant to wear and abrasion, corrosion, and
to chemical action
d. Dimensionally stable in all situations
e. Easily available at low cost
f. Repairable and reused
g. Able to take good surface finish

The wide variety of pattern materials which meet these characteristics are wood and wood
products; metal and alloys; plasters; plastics and rubber; and waxes.

Types of Patterns:

Single Piece or Solid Pattern

In a simple solid pattern, one side is made flat which serves as a parting surface. In this case, the
mold cavity will be entirely in the drag, and requires the more number of manual operations such
as cutting the gating system and repairing of the mold. The shape of the single piece pattern is
exactly same as that of casting. Single piece patterns are inexpensive and best suited for limited
production.

Fig: Split Pattern Fig: Single Piece Pattern

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Split Pattern

Split pattern is made in two parts. One part producing the mold in drag and the other in cope.
They are kept in position by dowel pins, and the split is usually arranged along the parting line to
draw the pattern easily out of the mold before pouring of molten metal. Split piece patterns are
used for intricate castings or castings of unusual shapes.

Multi Piece Pattern

Pattern with three or more parts is used for more complex castings. This type of pattern is known
as multi piece pattern. It requires molding box with three parts. The middle one is called cheek.

Loose Piece Pattern

Loose piece pattern is used to produce the castings having projections in the sides. Such design
makes impossible to draw the pattern from the mold. It is therefore necessary to make such
projection in loose piece and fastened to main pattern by means of anchor pin.

Fig: Loose Piece Pattern

Match Plate Pattern

In this case, pattern in two halves is attached on opposite side of wooden or metal plate (match
plate). Production efficiency and dimensional accuracy of castings can be generally improved by
the use of these patterns. Several patterns for small castings (need not be same) can be mounted
on one match plate. These are mostly used in machine molding as well as for producing large
number of small castings by hand molding.

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Fig: Sweep Pattern

Fig: Match Plate Pattern

Sweep Pattern

It is not a true pattern, but a template made of wood or metal revolving around a fixed axis in the
mold shapes the sand to the desired contour. This eliminates the need for a large three
dimensional pattern. It is suitable for producing simple symmetrical castings such as wheels,
rims, and bell shapes.

Runner:

Runner is a horizontal channel that receives molten metal from the sprue base, and distributes to
the ingates which carries metal to the mold. Runners are usually made trapezoidal in cross-
section. They are generally located in cope and ingates in the drag. This ensures that the slag and
dross are trapped in the upper portion of runner and only molten metal enters into the mold.

Runner Extension:

The runner is often extended beyond the last ingate to retain inclusions and various refractory
materials that may have been washed along the stream of molten metal. Also, it absorbs kinetic
energy causing a smooth flow of metal into the mold cavity.

Gates or Ingates:

Gates or ingates are openings through which molten metal directly enters into the mold cavity.
The gates should be designed such that the molten metal can flow steadily and quietly into the
mold cavity. They should be easily removed from the casting after solidification.

Tools and Equipment:

Molding Board
A molding board is a smooth wooden board on which the flask and pattern are placed when the
mould is being made. The figure is shown below:

Fig: Molding Boxes

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Molding Boxes
Sand moulds are prepared in specially constructed boxes called flasks. The purpose of flask is to
impart the necessary rigidity and strength to the sand in molding. They are usually made in two
parts, held in alignment by dowel pins. The top part is called the cope and the lower part the
drag. These flasks can be made by wood or metal depending upon the size required and the
purpose the flask must serve.

Shovel
A shovel is used for mixing and tempering molding sand and for moving the sand from the pile
to the flask as shown in figure below:
Riddle
A riddle sometimes called a screen consists of a circular or square wooden frame fitted with a
standard wire mesh at the bottom as shown in figure below. It is used to remove coarse sand
particles and other foreign material from the foundry sand.

Fig: Shovel Fig: Riddle Fig: Rammers

Rammer

A hand rammer is used for packaging or ramming the sand into the mould. One of its ends,
called the peen end, is wedge shaped and is used for packing sand in spaces, pockets and corners,
in the early stages of ramming. The other end called the butt end, has a flat surface and is used
for compacting the sand towards the end of molding as shown in below figure.
Strike Edge or Strike-Off Bar

It is a piece of metal or wood with straight edge as shown in below figure. It is used to
remove excess sand from the mould after ramming, to provide a level surface

Riser Pin

It is a straight wooden pin used to make a hole in the cope over the mold cavity for the molten
metal to rise-in and feed the casting to compensate the shrinkage that may take place during
solidification.
Sprue Pin

It is a tapered wooden pin, as shown in below figure. It is used to make a hole in the cope
through which the molten metal is poured into the mould.
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Slick

It is a small double ended tool having a flat on one end and a spoon on the other end as
shown in below figure. Slicks are used for repairing and finishing small surfaces of the
mould.

Lifter
Lifters are made of thin sections of steel of various widths and lengths with one end bent
at right angles as shown in below figure. They are used to clean and finish the bottom
and sides of deep, narrow openings in moulds.

Gate Cutter
It is a small piece of tin plate shape as shown in below figure. This serves as a tool for
cutting gates and runners in the mould.

Fig: Gate Cutters Fig: Vent Rods

Fig: Draw Spikes
Vent Rod
A vent rod or wire, as shown in below figure is used to make a series of small holes to
permit gases to escape while the molten in being poured.
Drawspike or Screw

The draw spike is appointed steel rod, with a loop at one end. It is used to rap a draw
patterns from the sand. Below figure shows two kinds of draw spikes. The draw spike is
threaded on the end to engage metal patterns.