Title: Fitting Work

Objective:
In the fitting operation one can practice cutting, filling, measuring, marking on Mild Steel (MS)
material with the help of various hand tool.
Introduction:
Working on components with hand tools and instruments, mostly on work benches is generally referred
to as ‘Fitting work’. The hand operations in fitting shop include marking, filing, sawing, scraping,
drilling, tapping, grinding, etc., using hand tools or power operated portable tools. Measuring and
inspection of components and maintenance of equipment is also considered as important work of fitting
shop technicians.
Types of fit:
a. Running fit
b. Press fit
c. Push Fit
d. Force Fit
Raw Materials:
Mild Steel (MS) plate of dimension ____x____x_____ mm3 .
Different Types of Tool:
1. Work Holding Tools
1.1 Bench Vice
The bench vice is a device commonly used for holding the work pieces.

1.2 C-Clamp
This is used to hold work against an angle plate or V-block or any other surface, when gripping is
required. It is also known as G-clamp.
2. Marking Tools
2.1 Marking table
A marking table is a heavily build cast iron table used for layout work on all sizes of jobs.
 Try-square

Scriber

2.2 Try-square
Try-square is used for checking the squareness of small works, when extreme accuracy as not required.
2.3 Scriber
A Scriber is a slender steel rod, used to scribe or mark lines on metal work pieces.
2.4 Odd-leg calliper
This is used for marking parallel lines from a finished edge and also for locating the centre of round
bars.
2.5 Dot Punches
This is used to locate centre of holes and to provide a small centre mark for divider point etc. For this
purpose, the punch is ground to a conical point having 60o included angle.
3. Measuring Tools
3.1 Callipers
These are used with the help of steel rule to check outside and inside measurements.
3.2 Steel rule
Steel rule is a surprisingly accurate measuring device. A rule is used to measure actual sizes of job or
work piece.
4. Cutting Tools
4.1 Hacksaw
The hacksaw is used for cutting metal by hand. It consists of a frame which holds a thin blade, firmly
in position. The blade has a number of cutting teeth. The number of teeth per 25 mm of the blade length
or teeth per inch (TPI) is selected on the basis of the work material and thickness being cut.

4.2 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 with machines. The following are the types, sizes and designations of twist
drills:

1. Straight shank.
Millimetres from 0.4 mm onwards
Inches from l/64" onwards
Letter drills A to Z
Number drills 60 to 20
2. Taper shank
Millimetres 3 to 100 mm
Inches 1/8" to 4"
 4.3 Taps and Tap Wrenches
A tap is a hardened steel tool, used for cutting internal threads after drilling a hole. Hand taps are usually
supplied in sets of three for each diameter and thread pitch. Each set consists of a taper tap, intermediate
tap and plug or bottom tap. The following are the stages involved in tapping operation:

1. Select the correct size tap, with the desired pitch. A thread is specified by its shape, size and pitch.
Ex: M20 × 2.5 (nominal dia 20 mm, pitch 2.5 mm Metric thread).
2. Select the correct size tap drill, usually indicated on the tap.
3. Drill the hole.
4. Secure the tap in the tap wrench.
5. Insert the first or taper tap in the drilled hole and start turning clockwise, by applying downward
pressure.
6. Check the alignment of the tap with the hole axis (verticality) with a try-square and correct it if
necessary, by applying sidewise pressure while turning the tap.
7. Apply lubricant while tapping.
8. Turn the tap forward about half a turn and then back until chips break loose. Repeat the process until
threading is completed with intermediate and bottom taps.
9. Remove them carefully. If it gets stuck, work it back and forth gently to loosen.
5. Finishing Tools
5.1 Files
Filing is one of the methods of removing small amounts of material from the surface of a metal part. A
file is a hardened steel tool, having slant 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.
Figure shows the parts of a hand file.
 5.1.1 Types of files
Hand file
Rectangular in section and tapered in thickness but parallel in width. The faces carry double cut teeth
and one of the edges single cut. The other edge, known as safe edge, does not have any teeth and hence
this file is also known as safe edge file. It is useful in filing a surface which is at right angles to an
already finished surface.

Flat file
It is rectangular in section and tapered for 1/3 length in width and thickness towards the tip. The faces
carry double cut teeth and the edges carry single cut teeth. It is a general-purpose file.

Square file
It is square in section and carry double cut teeth on all the four faces. It is tapered for 1/3 of its length towards
the point. Square files are used for filing corners and slots. It is also used to cut keyways.

Triangular square file

It is of equilateral triangular in section and tapers towards the tip. The faces are double cut and the
edges sharp. These files are used to file angular hole, and recesses. Used for sharpening wood saws.

Round file
It is tapered for 1/3 length with double cut on large coarse grades. Used for filing out round, elliptical and
curved openings.

6. Miscellaneous Tools
6.1 Striking tool (Hammer)
Hammers are named depending on their shape and material and specified by their weight. A ball peen
hammer has a flat face which is used for general work and the ball end particularly used for riveting.
They weigh from 200 gm to 1.5 kg
The hammer consists of a hardened and tempered steel head varying in mass from 0.1 kg to about 1 kg,
firmly fixed on a tough wooden handle.
The flat striking surface is known as the face, and the opposite end is called the peen. The most
commonly used is the ball-peen, which has a hemispherical end and is used for riveting over the ends
of pins and rivets.
For use with soft metals such as aluminium or with finished components where the workpiece could be
damaged if struck by a hammer, a range of hammers is available with soft faces, usually hide, copper,
or tough plastics such as nylon. The soft faces are usually in the form of replaceable inserts screwed into
the end or forced into a recess in the face.

Always use a hammer which is heavy enough to deliver the required force but not too heavy to be tiring
in use. The small masses, 0.1 kg to 0.2, are used for centre punching, while the 1 kg ones are used with
large chisels or when driving large keys or collars on shafts. The length of handle is designed for the
appropriate head mass, and the hammer should be gripped near the end of the handle to deliver the
required blow. To be effective, a solid sharp blow should be delivered and this cannot be done if the
handle is held too near the hammer head.

6.1.1 Types of Hammer:

a. Ball peen hammer
b. Cross peen hammer
c. Straight peen hammer

7. Procedure of Experiment:

8. Conclusion: