The document provides an overview of lathe machines, including their construction, types, attachments, accessories, safety practices, and operations. Key points include that a lathe removes metal to shape workpieces and operates by rotating the workpiece against a fixed cutting tool. It describes the main components of a lathe such as the bed, headstock, carriage, and tailstock. The document also covers various lathe types including engine, bench, turret, and CNC lathes, as well as common attachments like taper turning and grinding attachments.

1. Lathe Machine

2. Content:
 Introduction
 Construction
 Types
 Attachments
 Accessories
 Safety
 Lathe tools
 Lathe operations
 Turning calculations
 Turning parameters
 Taper turning with types

3. Introduction:
 Lathe is a machine, which removes the metal
from a piece of work to the required shape and
size.
 Lathe is one of the most important machine tools
in the metal working industry. A lathe operates on
the principle of a rotating work piece and a fixed
cutting tool.
 The cutting tool is feed into the work piece, which
rotates about its own axis, causing the work piece
to be formed to the desired shape.

4. Working Principle:

5. Working Principle:
 If the tool moves
parallel to work piece
cylindrical surface is
formed.
 If the tool moves
inclined to the axis it
produces a taper
surface and is called
taper turning.

6. Construction:
1. Lathe Bed
2. Head Stock
3. Quick change gear box
4. Carriage
5. Cross Slide
6. Apron
7. Tail Stock
8. Automatic Feed Lever
9. Feed of an Engine Lathe
10.Shear Pins and Slip Clutches

7. Lathe Bed:
 This is heavy rugged casting
made to support the working
parts of lathe and also guide
and align major parts of
lathe.
 Made to support working
parts of lathe.
 On top section are machined
ways.
 Guide and align major parts
of lathe.

8. Head Stock:
• The headstock houses the
main spindle, speed change
mechanism, and change gears.
• The headstock is required to
be made as robust as possible
due to the cutting forces
involved, which can distort a
lightly built housing and
Induce harmonic vibrations
that will transfer through the
work piece, reducing the
quality of the finished work
piece.

9. Quick Change Gear Box:
 The quick change gear box
is located in the head stock
portion of the lathe it has
following two functions:
• Contains number of
different-size gears.
• Provides feed rod and
lead-screw with various
speeds for turning and
thread-cutting operations

10. Continued:
 The arrangement which are employed in feed
gear boxes to obtain multi spindle speeds and
different rates of feeds are:
 Sliding Gear Mechanism
 Sliding Clutch Mechanism
 Gear Cone And Tumbler Gear Mechanism
 Sliding Key Mechanism
 Combination of any two or more of the above
 Usually two or three levers must be moved to
obtain the desired combination within a given
range.

11. Carriage:
 Used to move cutting
tool along lathe bed.
 Consists of three main
parts:
 Saddle
 Cross slide
 Apron

12. Continued:
 Movement of entire carriage assembly along the
bed provides feed for the tool parallel to the
lathe axis.
 The compound rest can be swiveled on the
cross slide in the horizontal plane about vertical
axis.
 To the front of the carriage is attached the
apron. It is fastened to the saddle and hangs
over the front of the bed.
 The apron houses the automatic feed
mechanism for longitudinal and cross feeds and
the split nut for thread cutting.

13. Cross Slide:
• Mounted on top of saddle.
• Provides manual or automatic cross movement for
cutting tool.

14. Apron:
 Fastened to saddle.
 Houses gears and
mechanism required to
move carriage or cross-
slide automatically.
 Locking-off lever inside
apron prevents engaging
split-nut lever and
automatic feed lever at
same time.
 Apron hand wheel turned
manually to move carriage
along lathe bed

15. Tail stock:
• Upper and lower tailstock castings.
• Adjusted for taper or parallel turning by two screws
set in base.
• Tailstock clamp locks tailstock in any position along
bed of lathe.
• Tailstock spindle has internal taper to receive dead
center.
• Provides support for right-hand end of work.

16. Continued:
 In tail stock jobs of different
lengths are provided with
quill which can be moved
in and out by means of a
screw and then locked in
position.
 The movement of the quill
is parallel to the lathe axis.
 The quill has a tapered
bore into which is fitted a
hardened centre which
locates and holds the w/p
when turning between
centre.
 This bore may also be

17. Automatic Feed Lever:
• Engages clutch that provides automatic feed to
carriage.
• Feed-change lever can be set for longitudinal feed or
for cross-feed.
• In neutral position, permits split-nut lever to be
engaged for thread cutting.
• Carriage moved automatically when split-nut lever
engaged

18. Feed of an Engine Lathe:
 Distance carriage will travel in one revolution of
spindle.
 Depends on speed of feed rod or lead screw.
 Controlled by change gears in quick-change gearbox.
 Obtains drive from headstock spindle through end
gear train.
 Chart mounted on front of quick-change gearbox
indicates various feeds.

19. Shear Pins and Slip Clutches:
 Prevents damage to feed
mechanism from
overload or sudden
torque
 Shear pins:
 Made of brass
 Found on feed rod,
lead screw, and end
gear train.
 Spring-loaded slip
clutches:
 Found only on feed
rods
 When feed
mechanism.

20. Types:
 Following are the types of the lathe machines:
 Engine lathe
 Bench lathe
 Tracer lathe
 Tool room lathe
 Automatic lathe
 Turret lathe
 CNC lathe

21. Engine Lathe:
 This term ‘engine’ is associated with the lathe owing
to the fact that early lathes were driven by steam
engine.
 It is also called centre lathe.
 The most common form of lathe, motor driven and
comes in large variety of sizes and shapes.

22. Continued:
Engine lathes are classified according to the various
designs of headstock and methods of transmitting
power to the machine.
 Belt Driven Lathe
 Motor Driven Lathe
 Gear Head Lathe
 The power to the engine lathe spindle may be given
with the help of a belt drive from an overhead line
shaft but most modern machines have a captive
motor with either a cone pulley driven or an geared
headstock arrangement.

23. Bench Lathe:
 A bench top model usually of low power used to
make precision machine small work pieces.
 It is used for small w/p having a maximum swing of
250 mm at the face plate.
 Practically it consists of all the parts of engine lathe
or speed lathe.

24. Tracer Lathe:
 A lathe that has the ability to follow a template to copy
a shape or contour.

25. Tool Room Lathe:
A tool room lathe having features similar to an engine
lathe is much more accurately built and has a wide
range of spindle speeds ranging from a very low to a
quite high speed up to 2500 rpm.
 This lathe is mainly used for precision work on a tools,
dies, gauges, and in machining work where accuracy is
needed.
 This lathe machine is costlier than an engine lathe of
the same size.

26. Automatic Lathe:
 A lathe in which the work piece is automatically fed
and removed without use of an operator.
 It requires very less attention after the setup has
been made and the machine loaded.

27. Continued:
Once tools are set and the machine is started it
performs automatically all the operations to finish
the job.
 After the job is complete, the machine will continue
to repeat the cycles producing identical parts.
 An operator can maintain five or six such a types of
lathes at a time simply look after the general
maintenance of the machine and cutting tools.

28. Turret Lathe:
 Turret lathe is the
adaptation of the engine
lathe where the tail stock is
replaced by a turret
slide(cylindrical or
hexagonal).
 Tool post of the engine
lathe is replaced by a
square cross slide which
can hold four tools.
 It is used in mass
production.

29. Continued:
 It has heavier construction and provides wider range
of speeds.
 The saddle carrying the turret head moves along the
whole length of the bed.
 Much longer jobs can be machined.
 Turret head directly mounted on the saddle.
 The front tool post can carry 4 tools and rear tool
post may have 1 or 2 tools.
 Turret may have4 to 6 tools.
 More than one tool may be set to operate
simultaneously.
 There is no lead screw.

30. CNC Lathe:
 A highly automated lathe, where both cutting, loading,
tool changing, and part unloading are automatically
controlled by computer coding.

31. Attachments:
 The commonly used attachments are:
 Taper turning attachment
 Ball turning attachment
 Thread Chasing Dial
 Eccentric turning attachment
 Grinding attachment

32. Taper Turning Attachment:
 The principle of turning
taper by a taper
attachment is to guide the
tool in a straight path set
at an angle to the axis of
rotation of the work
piece.
 The work is being
revolved between centers
or by a chuck aligned to
the lathe axis.

33. Continued:
 A taper turning
attachment consists
essentially of a bracket or
frame which is attached
to the rear end of the
lathe bed and supports a
guide bar pivoted at the
centre.
 The bar having
graduations in degrees
may be swiveled on
either side of the zero
graduation and is set at
the desired angle, with
the lathe axis.

34. Ball turning attachment:
 It is an attachment mounted on the cross slide after
removing the compound rest.
 It is used for turning segment and sphere. It is in
two halves, lower half and upper half.
 Lower half is fixed with the cross slide and upper
half can be rotated with the help of a lever.

35. Continued:
 There is a tool block on
the top of the upper half
in which provision is
made to hold the tool
firmly.
 Tool block can be
moved towards the
centre or away from the
centre to facilitate the
turning of different
diameter balls.

36. Thread Chasing Dial:
 When cutting threads
one has to take several
cuts and for this the
tool has to be
withdrawn from the
thread on completion of
each cut and again
brought to starting
position.
 If the tool does not
follow the path, the
threads will be spoiled.
 So to achieve this,
thread chasing dial is

37. Continued:
 The chasing dial
overcomes the difficulty
of catching the threads
at correct start.
 It consists of
graduated dial that is
connected to a worm
wheel
 The worm is in mesh
with the lead screw, so
that if the saddle is
stationary, the lead
screw acts as a worm

38. Eccentric Turning Attachment:
 It refers to the turning of certain diameters at
different lengths on the same shaft or jobs whose
axis is not falling in line with the main axis.
 A crank shaft of an engine is the example of such
job. This type of attachment is equipped with the
provision of shifting the centers of the work away
from the lathe spindle axis.
 An accurate marking and truing is of prime
important in the sequence of operation of jobs of
this nature.

40. Grinding Attachment:
 It is also called tool
post grinder.
 It is mounted on the
compound rest in place
of tool post. This
attachment consists of
a base plate, grinding
wheel and a motor.
 The job is held in a
chuck or between
centres.
 It is extensively used
for grinding lathe

41. Continued:
 With this attachment many other grinding
operations can be performed on the lathe.
 It is a useful attachment, which can be mounted
on any lathe.
 It can grind hardened work and ensures a fine
finish. Internal grinding can also be done with this
grinder.

42. Accessories:
 Divided into two categories
 Work Holding Devices :
 Lathe centers, chucks, faceplates
 Mandrels, steady and follower rests
 Lathe dogs, drive plates
 Cutting-tool-holding devices:
 Straight and offset tool holders
 Threading tool holders, boring bars
 Turret-type tool posts

43. Lathe Centers:
 Work to be turned between centers must
have center hole drilled in each end Support during
cutting.
 Most common have solid Morse taper shank 60º
centers, steel with carbide tips.
 Care to adjust and lubricate occasionally

44. Continued:
 Lathe centers is used as
a support at the end
of a work. It is usually
made from carbon tool
steel.
 There are three (3) main
types of Lathe
centers:
 Live centre (Revolving
centre)
 Dead centre
 Half centre

45. Chuck:
 Used extensively for holding work for
machining operations Work large or unusual
shape
 Most commonly used lathe chucks are:
 Three-jaw universal
 Four-jaw independent
 Collet chuck

46. Lathe Dogs:
 A lathe dog ( lathe
carrier) is a device that
clamps around the
work piece and allows
the rotary motion of the
machine's spindle to
be transmitted to the
work piece.
 A carrier is most often
used when turning
between centers on a
lathe.

47. Faceplate:
 A faceplate is the basic work holding accessory
for a lathe.
 It is a circular metal plate which fixes to the end
of the lathe spindle.
 The work piece is then clamped to the faceplate,
typically using t-nuts in slots in the faceplate, or
less commonly threaded holes in the faceplate
itself.

48. Driver Plate:
 Provide the drive when turning between centres.

49. Steady Rest :
 Used to support long work held
in chuck or between lathe
centers.
 Prevent springing.
 Located on and aligned by
ways of the lathe.
 Positioned at any point along
lathe bed.
 Three jaws tipped with plastic,
bronze or rollers may be
adjusted to support any work
diameter with steady rest
capacity.

50. Follower Rest:
 Mounted on saddle
 Travels with carriage to prevent work from
springing up and away from cutting tool
 Cutting tool generally positioned just ahead of
follower rest
 Provide smooth bearing surface for two jaws
of follower rest

51. Follower Rest:

52. Mandrels:
 Holds internally machined work piece between
centers so further machining operations are
concentric with bore
 Several types, but most common:
a) Plain mandrel
b) Expanding mandrel
c) Gang mandrel
d) Stub mandrel

53. (A) (B)
(C) (D)

54. Straight Tool Holder:
 General-purpose type
 Used for taking cuts in either direction and for general
machining operations
 Designated by letter S

55. Left Hand Offset Tool Holder:
 Offset to the right
 Designed for machining work close to chuck or
faceplate and cutting right to left
 Designated by letter L

56. Right Hand Offset Tool Holder:
 Offset to the left
 Designed for machining work close to the
tailstock and cutting left to right
 Also for facing operations
 Designated by letter R

57. Safety Of Lathe Machine:
All lathe operators must be constantly aware of the
safety.
Handle sharp cutters, centres, and drills with care.
Remove chuck keys and wrenches before operating.
Always wear protective eye protection.
Always stop the lathe before making adjustments.
Know where the emergency stop is before operating
the lathe.
Correct dress is important, remove rings and watches.
Do not change spindle speeds until the lathe comes to
a complete stop.

59. Lathe Tools:

60. Lathe Tools:

61. Lathe Tools:

62. Lathe Operations:
 Turning: to remove material from the outside diameter of a
workpiece to
obtain a finished surface.
 Facing: to produce a flat surface at the end of the
workpiece or for making
face grooves.
 Boring: to enlarge a hole or cylindrical cavity made by a
previous process
or to produce circular internal grooves.
 Drilling: to produce a hole on the work piece.
 Reaming: to finishing the drilled hole.
 Threading: to produce external or internal threads on the
work piece
 Knurling: to produce a regularly shaped roughness on the
work piece.

63. Lathe Operations:

64. Turning:

65. Facing:

66. Knurling:

67. Grooving:

68. Parting:

69. Chamfering:

70. Drilling:

71. Tapering:

72. Forming:

73. Turning Calculations:

74. Turning Parameters:
 Cutting Speed
 Factors determining cutting speed
 Setting cutting speed

75. Cutting Speed:
 Cutting speed for turning is the speed at which
the work rotates.
 This is also known as surface speed.
 Rate at which point on work circumference travels
past cutting tool.
 expressed in meters per minute (m/min)
 Important to use correct speed for material:
 Too high: cutting-tool breaks down
rapidly
 Too low: time lost, low production rates

76. Factors Determining Cutting
Speed:
 The softer the work material, the faster the
recommended cutting speed.
 The harder the cutting tool material, the faster the
cutting speed.
 The depth of the cut and the feed rate will also
affect the cutting speed, but not to as great an
extent as the work hardness.

78. Some Other Factors:
 The material being cut
 The rigidity and condition of the machine
 The material of which the tool is made from
 The depth of cut and the feed rate
 Availability of coolant (cutting fluid)

79. Setting Cutting Speed:
 Speeds measured in revolutions per minute
 Changed by stepped pulleys or gear levers
 Belt-driven lathe
 Various speeds obtained by changing flat belt and
back gear drive
 Geared-head lathe
 Speeds changed by moving speed levers into
proper positions according to r/min chart fastened to
headstock

80. Lathe Recommended Speeds:

81. Feed:
 Feed rate (also often
styled as a solid
compound, feed rate, or
called simply feed) is the
relative velocity at which
the cutter is advanced
along the work piece.
 its vector
is perpendicular to the
vector of cutting speed.
 Feed rate units depend
on the motion of the tool
and work piece.
 Feed rate is defined as
the distance the tool

82. Depth Of Cut:
 Depth of cut is defined as distance that the
cutting tool is fed in the job.
 Cutting speed and feed rate come together
with depth of cut to determine the material
removal rate, which is the volume of work piece
material (metal, wood, plastic, etc.) that can be
removed per time unit

83. Taper Turning:
 Taper turning means, to produce a conical
surface by gradual reduction or increase in
diameter from a cylindrical work piece.
 This tapering operation has wide range of use in
construction of machines.
 Almost all machine spindles have taper holes
which receive taper shank of various tools and
work holding devices.

84. Taper Turning Method:
 A taper may be turned by any one of the following
methods:
 By a broad nose form tool.
 By setting over the tailstock centre.
 By swiveling the compound rest.
 By a taper turning attachment
 By combining longitudinal and cross feed in a
special lathe.

85. By Broad Nose Form Tool:
 A broad nose tool having
straight cutting edge (form
tool) is set on to the work at
half taper angle, and is fed
straight into the work to
generate a tapered surface.
 In this method the tool angle
should be properly checked
before use.
 This method is limited to turn
short length of taper only.
 Tool will require excessive
cutting pressure, which may
distort the work due to
vibration and spoil the work

86. Taper Turning By Tail Stock
Method:
 The principle of turning taper
by this method is to shift the
axis of rotation of the work
piece, at an angle to the
lathe axis, and feeding the
tool parallel to the lathe axis.
 The angle at which the axis
of rotation of the work piece
is shifted is equal to half the
angle of the taper.
 The body of the tailstock is
made to slide on its base
towards or away from the
operator by a set over screw.
 The amount of set over
being limited, this method is
suitable for turning small

87. By Swiveling the Compound
Rest:
 This method employs the principle of turning
taper by rotating the work piece on the lathe axis
and feeding the tool at an angle to the axis of
rotation of the work piece.
 The tool mounted on the compound rest is
attached to a circular base, graduated in degree,
which may be swiveled and clamped at any
desired angle.
 Once the compound rest is set at the desired half
taper angle, rotation of the compound slide screw
will cause the tool to be fed at that angle and
generate a corresponding taper

89. By Compound Rest Method:
 The principle of turning
taper by a taper attachment
is to guide the tool in a
straight path set at an angle
to the axis of rotation of the
work piece.
 A taper turning attachment
consists essentially of a
bracket or frame which is
attached to the rear end of
the lathe bed and supports
a guide plate pivoted at the
centre.
 The plate having
graduations in degrees may
be swiveled on either side
of the zero graduation and
is set at the desired angle

90. Taper Turning By Combining
Feeds:
 Taper turning by combining feeds is a more
specialized method of turning taper.
 In certain lathes both longitudinal and cross
feeds may be engaged simultaneously causing
the tool to follow a diagonal path.
 This is the resultant of the magnitudes of the two
feeds.
 The direction of the resultant may be changed by
varying the rate of feeds by change gears
provided inside the apron.