Introduction:

The lathe is one of the most important machines in any workshop. Its main
objective is to remove material from outside by rotating the work against a cutting tool.
It is a power driver, well purpose machine tool, which is used for producing cylindrical
work piece.
A lathe is a power driven machine tool used to turn and cut metal which rotates the work
piece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or
deformation with tools that are applied to the work piece to create an object which has
symmetry about an axis of rotation. Most suitably equipped metalworking lathes can also be
used to produce most solids of revolution, plane surfaces and screw threads or helices. The
material can be held in place by either one or two centers, at least one of which can be moved
horizontally to accommodate varying material lengths. Other work holding methods include
clamping the work about the axis of rotation using a chuck or collets, or to a faceplate, using
clamps or dogs.

Objectives:
1. To make a bolt.
2. To know the advantages and disadvantages of a lathe machine.
3. To know about various parts and their functions.
4. To know about feeding and threading mechanism.

Types of Lathe Machine:

 Speed lathe
 Bench lathe
 Engine lathe
 Tool room lathe
 Capstan and turret lathe
 Automatic lathe
 Special purpose lathe

Main parts of a lathe:

The bed
The bed is the base or foundation of the lathe. It is a heavy, rigid casting made in one piece.
Since it is the “backbone” of the lathe, it holds or supports all the other parts .Almost all
lathes have a bed, which is (almost always) a horizontal beam.

The headstock
The headstock is a permanently fastened to the left end of the lathe. It contains the headstock
spindle, which is rotated by gears or by a combination of gears. At one end of the bed (almost
always the left, as the operator faces the lathe) is a headstock. The headstock contains high-
precision spinning bearings.

The tailstock
The tailstock can be moved along the bed ways and clamped in position. It consists of two
casting or main parts. The counterpoint to the headstock is the tailstock, sometimes referred
to as the loose head, as it can be positioned at any convenient point on the bed, by undoing a
locking nut, sliding it to the required area, and then relocking it.

The carriage
Metalworking lathes have a carriage (comprising a saddle and apron) topped with a cross-
slide, which is a flat piece that sits crosswise on the bed, and can be cranked at right angles to
the bed. Sitting atop the cross slide is usually another slide called a compound rest, which
provides 2 additional axes of motion, rotary and linear.

The feeding and threading mechanism: The feeding and threading mechanism consists of a
quick change gear box, a lead screw, a feed rod and the gears and the clutches in the apron.
The quick change gear box is directly below the headstock assembly.
Headstock

Dead center
Gear box

Tool post

Tailstock

Carriage

Fig-1: Different parts of the lathe machine

Sequence of operations:
The operations are needed to make a bolt:

Turning
The operation of metal removing process from a work piece.

Thread cutting
It is the process of cutting thread on the work piece.

Necking
To remove metal by a parting tool.

Facing
Facing is the process of removing metal from the end of a work piece to produce a flat
surface.

Knurling
It is the process of making rough surface for gripping work piece.

Chamfering
It is the process of making tapper turning.

Power flow diagram:

Motor
Working procedure:

Fig: Power flow diagram of lathe machine

Working principle:
1. At first counter sinking was done by drill and counter sink to hold the job.
2. Then turning operation was done by V- tool in lathe machine.
3. Next necking was done to separate the knurling portion and threading portion.
4. Then threading was done which was operated by quick change gear box. Twelve
threads in one inch were done in this experiment.
5. After that knurling was done by knurling tool to grip the object.
6. Finally, chamfering was done by V-tool and machining was done.

Knurling
Necking

Threading
Champaring

Fig-2: Making bolt by lathe machine

Knurling
Necking
Threading

Facing
 Fig-3: Required bolt

Application
Bolt is generally used for joining two surfaces and various joining purposes.

Safety
1. We must always wear safety glasses of the correct type.
2. After setting up the lathe, remove all wrenches, oilcans and other tools from the work area.
3. Always stop the lathe before making adjustments of any kind.
4. Do not change spindle speeds until the lathe comes to a dead stop.
5. Never attempt to measure work while it is turning.
6. Lathe machine should be stopped before making adjustments to the tool
holder.
7. A lathe chip is both hot and sharp and should never be touched by hand.
8. Chuck key should not be leaved in the chuck.
9. It is bad practice to stop the lathe before the required length of knurl is
completed.
10. A brush should be used to remove the chips resulting from a knurling
operation.
11. In case of emergency, the emergency stop should be used to stop the
machine.
12. For smooth working and to prevent the job from becoming too much hot,
the cooling fluid should be used.

Conclusion
Machine shop provides us the opportunity to learn how to prepare different jobs on ground.
This is of immense importance and of extreme practical usefulness to prepare such jobs in the
machine shop, which will make the students beneficiary in the long run. In spite of having
some limitations of our own, we performed this operation successfully and we hope it will
help in our future life.