Turning workpiece

COMPETENCY BASED LEARNING MATERIAL

Sector:

Metals and Engineering

Distinctive Area of Competence and Qualifications:

Machinist NC 1

Unit of Competency:

Turn Workpiece

Module Title:

Turning Workpiece

Institution:

TECHNICAL EDUCATION AND SKILLS DEVELOPMENT AUTHORITY
National Institute for Technical Vocational Education and Training

Service Road, South Superhighway, Taguig Metro Manila, Philippines

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HOW TO USE THIS LEARNING MATERIAL

Welcome to the Competency–Based Learning Material for the module;
Turning Workpiece. This Competency –based learning material contains
activities for you to complete.

The unit of competency “Turn Workpiece” contains the knowledge, skills
and attitudes required for Machinist. It is one of the Core Modules for in the
National Certificate Level (NC __1_).

You are required to go through a series of learning activities in order to
complete each learning outcome of the module. In each learning outcome there
are learning resources to help you better understand the required activities.
Follow these activities on your own, and answer the self-check at the end of each
learning outcome/activity. Use the blank answer sheets at the end of the module
to reflect your answers for each self-check. If you need clarification on the
technical terms use in this module, refer to the “Definition of Terms”. If you have
questions, please don’t hesitate to ask your trainer for assistance.

Recognition of Prior Learning (RPL)

You may have some or most of the knowledge and skills covered in this
learner’s guide because you have:

 Been working for some time.
 Already completed training in this area.

If you can demonstrate to your trainer that you are competent in a
particular skill, you don’t have to do the same training again.

If you feel you have some of the skills, talk to your trainer about having
them formally recognized. If you have qualification or Certificates of Competence
from previous training, show it to your trainer. If the skills you acquired are still
relevant to the module, they may become part of the evidence you can present
for RPL.

At the end of this module is a Learner’s Diary, use this diary to record
important dates, jobs undertaken and other workplace events that will assist you
in providing further details to your trainer or assessors. A Record of
Achievement is also provided for your trainer to fill-up once you completed the
module.

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QUALIFICATION : NC Level: 1

UNIT OF COMPETENCY : Turn Workpiece

MODULE TITLE : Turning Workpiece

INTRODUCTION :

The job of a lathe setter/operator embraces a wide coverage. It ranges
from a simple set-up of cutting tools to machining workpieces into finished
products. He is also expected to take care and maintain the machine.

However, the functions mentioned above our carried out only if the
lathe operator knows very well the nomenclature, the operation and processes.
Therefore, it is imperative that you equip yourself with the basic knowledge, skills
and work techniques in operating and machining in a lathe.

Hopefully, you find this resource package guest help.

LEARNING OUTCOME : At the end of this module you will be able to:
(Summary of Learning outcomes).

1. Determine job requirements.
2. Set-up workpiece
3. Perform turning operation, check and measure workpiece.

ASSESSMENT CRITERIA (Summary of Assessment Criteria)
1. Determine job requirements.
1.1 Set up workpiece
1.2 Plans/drawings interpreted to specification.
1.3 Sequencing of operation is determined to produce component
specification
1.3 Cutting tools and work holding devices are selected according to
job requirement
1.4 Workpiece is set up to required level of accuracy using
instrument/equipment according to work procedure
1.5 Set up operations are performed applying knowledge in safety
procedures and using personal protective devices
1.1 Speed and feed are calculated using appropriate mathematical
techniques and reference material
1.2 Lathe accessories used are appropriate to the requirement of the
operations
1.3 Lathe operations are performed to produce component to
specifications in the working drawing; operations are performed
applying knowledge on safety procedure and using PPE
1.4 Workpiece is checked in conformity of specifications using appropriate
techniques, of measuring tools and equipment

PREREQUISITE: Before you take this module you must complete first the
module on: Bench Work NCI

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Qualification : NC Level I

Module Title : Turning Workpiece
Determine job requirements.
Learning Outcome #1 :

Assessment Criteria :

1. Plans/drawing interpreted according to specification
2. Sequencing of operation is determined to produce

component to specification.
3. Work holding devices are selected according to the

requirements.
4. Cutting tools are selected, inspected, mounted according

to manufacturers specification and work procedure.
5. Machine guards, coolants, and dust extraction devices

are check according to work requirements.

Resources: Human Resources,
Learning Guides
Machines Shop Practice 1 & 2,
Shop Theory,
Machine Tool Technology

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Qualification: NC Level I

Module Title: Turning Workpiece

Learning Outcome #2: Set up Workpiece.

Assessment Criteria:

1. Workpiece is mounted and centered in chuck to
required level of accuracy using tools and
equipment in accordance with work procedure.

2. Workpiece is setup to required level of accuracy
using equipment, instrument according to work
procedure.

3. Set-up operations are performed applying
knowledge on safety procedures and using
personal protective devices.

Resources: Human Resources,
Learning Guides
Machines Shop Practice 1 & 2,
Shop Theory,
Machine Tool Technology

6

Qualification: NC Level I

Module Title: Turning Workpiece

Learning Outcome #3: Performing Turning Operation

Assessment Criteria:

1. Speed and feed are calculated using appropriate
mathematical
techniques and reference materials.

2. Lathe accessories used are appropriate to the
requirement of the operations.

3. Lathe operation is performed to produce
component to specifications in the drawing.

4. Operations are performed applying knowledge in
safety procedure and using personal protective
devices.

5. Workpiece is checked forming to specifications
using appropriate techniques of measuring
instruments and equipment.

Resources: Human Resources,
Learning Guides
Machines Shop Practice 1 & 2,
Shop Theory,
Machine Tool Technology

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LEARNING EXPERIENCES/ACTIVITIES

Learning Outcome # 1: Determine Job Requirements

Learning Activities Special Instructions

1. Read: resources to interpret  Level one practical task
plans/drawing.
 Machine tools and manufacturing
2. Read: Resource to determine Technology, Krar, Steve F. et al pp.
sequence of operation. 254-255
Operation Sheet no. 1
3. Check the sequence of operation.
 Machine tools and manufacturing
4. Read: Resource on how to select Technology, Krar, Steve F. et al pp.
& mount cutting tools, selects 222-250
work holding devices, and check
machine guards and coolant Safety Manuals on Machines
level.

Learning Outcome # 2: Set up Workpiece 8
Learning Activities Special Instructions

1. Read: Resource on how to mount  Info. Sheet no. 4 Mounting Work
and center in chuck to Between Centers, Machine
required level of accuracy Tools Mfg. Technology
using equipment, measuring pp.251-258
instrument.
Machine Tool Operation
2. Read: Resource on Safety tips- pp. 185
do’s and don’ts regarding turning
operation.  Info Sheet no.3

3. Do: Set up  Operation Sheet no. 4

Learning Outcome # 3: Turn Workpiece 9
Learning Activities Special Instructions

1. Read: resource to compute  Info. Sheet no. 5
speed and feed.
Info Sheet no. 1
2. Read: Resource on Lathe  Info Sheet no.3
Machine accessories and uses.
 Operation Sheet no. 4
3. Read: Resource on Turning  Operation Sheet no. 4
Safety Rules.
Self check on turning operation
4. Do: Turning Operation
5. Do: Check workpiece.
6. Complete: Self-check

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DEFINITIONS OF TERMS:

1. Alloys- is mixture of two or more metals.
2. Attachment-additional parts of accessories provided in a machine to help
perform an operation or a series of operations
3. Binding- an act of tying together.
4. Carbon Steel- an alloy of metal used for making cutting tools
5. Center points- marks, which are laid out on ends of cylindrical stock and used
as guides to drill center holes of pilot holes.
6. Compounds- are substances, which consist of two of more atoms of elements
which can be broken down into two of more single atom by simple chemical
change.
7. Compressive Strength- Resistance to forces tending to compress, shorten or
crush.
8. Dial Indicator- a dial gauge used for checking accuracy of centering.
9. Diameter- aligns dividing a circle into halves.
10. Ductile- is a property of a metal, which can be stretched, or turn into tin
sheets without
breakings.
11. Element- is a substance which consists of a single atom which cannot be
broken

into 2 or more single atom.
12. Facing- an operation of squaring the ends of a cylindrical stock.
13. Force- that which changes or tends to change the station of rest or motion

of the body acted upon.
14. Grip- a device for grasping or holding
15. Hardened Metal- a piece of metal treated with heat to become hard.
16. Headstock Spindle- is tapping red on the front end to receive or fit the live
center.
17. Lubricant- material used for lubricating e.g. grease, white lead, etc.
18. Metal- used only to designate the elementary metallic substance but those
refined or partially refined products of the ores, which have such
characteristics as ductility, malleability, fusibility, etc.
19. Pilot or Center Hole- serves as a guide for drilling a bigger hole or guide for
the points of lathe center.
20. Punch- a shearing tool made of steel, use to remove material whose shape
is the same as that of the punch.
21. Steel – is an alloy of iron and carbon
22. Solder- an alloy use for joining metals together under heat.
23. Temperature- is the measure of the hotness of coldness of a body.
24. Tensile Strength - the strength necessary to enable a bar or structure to
resist a tensile strain.

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25. Attachments – additional parts or accessories of provided in machine to help

perform an operation or a series of operations.
26. Binding – An Act of tying together
27. Carbon steel – an alloy of metal used for making cutting tools.
28. Center points – marks which are laid out on ends of cylindrical stock and

used as guides to drill center holes or pilot holes.
29. Dial indicator – a dial gauge used for checking accuracy of centering.
30. Diameter – A line dividing a circle into halves
31. Facing – an operation of squaring the ends of a cylindrical stock.
32. Hardened metal – a piece of metal treated with heat to become hard.
33. Headstock spindle – is tapered on the front end to receive or fit the live

center.
34. Lubricant – material used for lubricating, e.g. Grease, white lead, etc.
35. Pilot or center hole – serve as a guide for drilling a bigger hole or guide for

the point of lathe center.
36. Carbon steel – are alloys of iron and carbon.
37. Alloys – are mixture of two or more metals

- Combination of a metallic element and one or more different

elements.
38. Element – is a substance which consist of a single atom which can not be

broken into two or more single atom.
39. Steel – is an alloy of iron and carbon.
40. Ductile – is a property of metal which can be stretched or turn into thin sheet

without breaking.
41. Temperature – is a measure of hotness or coldness of a body.
42. Compound – is a substance which consist of two or more atoms of elements

which can be broken down into the two or more single atom by simple

chemical change.
43. Metal – Used not only to designate the elementary metallic substance but

those refine products of the are which have such characteristic body acted

upon.
44. Force – That which changes or tends to change the station of rest or motion

of the body acted upon.
45. Solder – an alloy used for joining metals together under heat.
46. Fracture – To break apart, to separate continuous parts of an object by

sudden shock or excessive strain.
47. Punch – A shearing tool made of steel, used to remove material whose

shape is in the same as that of the punch.
48. grip – A device for griping and holding.
49. Tensile strength – The strength necessary to enable a bar or structure to

resist a tensile strain.
50. Compressive strength – Resistance to forces tending to compress, shorten

or crush.

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LO1 – Set up Workpiece

Activity Sheet No.1
On interpreting symbols

(Eng communication)

Supplies/ materials
1. Working drawing
2. Workpiece

Procedure:
Given the workpiece

STEPPED SHAFT

1. Note the specific measurement of the workpiece.
2. Determine the unit of measurement.
3. Tell your instructor what the workpiece is all about.

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Checklist on the Criteria for Oral Assessment in Eng Communication

1. Does the trainee speak correct English? YES NO
 
2. Does the trainee demonstrate  
confidence?  

3. Does the trainee observe proper  
pronunciation?  

4. Does the trainee organize the ideas
clearly?

5. Does the trainee show mastery of the
procedures in setting up workpiece?

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Activity Sheet No. 1

(Math)
Title: Applying Ratio and Proportion in Determining R. P. M.
Equipment: Lathe Machine
Procedure:

1. Go to the workshop and get the following data of the lathe machine.

Lathe Machine Parts Diameters No. of Teeth R.P.M.

1. R.P.M of motor
2. Diameter of Driven Pulley
3. Diameter of Driven Pulley

4. No. of teeth of leads crew
(driven gear)

5. No. of teeth of lead screw
(driven gear)

Speed of gear can be expressed as follows:
Teeth on driven = Revolutions of driven
Teeth on driven Revolutions of driven

Rule: To find the speed of either gear, multiply the size and speed of the other
gear an divide by the size of the gear the size of the gear.

Example 1. Two mashing gear have 40 and 60 teeth. If the smaller gear makes 120 r.p.m,
how many r.p.m will large pulley make?

Solution: r.p.m of large gear = size x r.p.m of small gear
size of large gear

= 40 x 120 = 80 r.p.m
60

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Identifying Drawing Standard and
Alphabet of Lines

Purpose: Prerequisite is to identify drawing standard and alphabet lines.

Condition or Situation for the operations

A prerequisite to reading and writing of a language is an alphabet.
Drawing as a graphical language, has its own alphabet known as Alphabet of Lines.
An alphabet of Lines is a set of conventional lines used in drawing. It is a basic
information in reading and understanding of a technical drawing.

ALPHABET OF LINES commonly used in drawing:

1. Visible Lines – are thick solid lines to represent the outline of the
object that can be seen from view. This is heavy lines or it
may be selected to suit the size of the drawing and the sheet.

2. Invisible Lines – are medium lines consisting of equally space short
dashes of about .3 cm. Long and .1 cm. Apart. These are
used to indicate hidden features of the object. Sometimes
called hidden lines.

3. Center Lines – are thin lines made of an alternate long and short
dashes used to indicate center of entire objects and indicate
location of circular features. For long dash it is approximately
1.5 cm. To 3 cm. Long and the short dash is approximately
.3 cm. long with a gap of .1 cm.

4. Extension Lines – are thin long lines used to assist in showing the
limit of dimension. It is also used to project edges of the
objects from one view to the other. It is sometimes called
‘’witness lines’’.

5. Dimension Lines – are thin long unbroken lines expect to permit
insertion of dimension. Dimension lines terminate with
arrowheads on both ends. It tell the distance measured.

6. Cutting Plane Lines – are thick lines consisting of one long and two short dashes
alternating. The long is approximately 1.5 to 3 cm. long and the short dash
is .3 cm. long with a gap of .1 cm. between dashes. It is use to indicate the
path of the imaginary cut in sectioning.

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7. Section Lines – are thin evenly spaced lines usually inclined at an
angle of 45 degrees. It is indicate exposed cut surface of the
object. It is sometimes called crosshatching lines.

8. Long Break Lines – are thin lines with a straight portion and a zigzag.
these lines indicate that the structures has broken to permit
convenient to proportion on the paper.

9. Short Break Lines – are thick lines freehand. This is used to indicate
short in the structure. Break lines also conserve space on a

drawing sheet.

10. Adjacent-Part or Alternate-Position Lines – are thin consisting of
long dashes used to show adjacent parts or alternate position
of parts. The dashes are approximately .5 cm. Long with a
gap of .1 cm. Between.

11. Ditto Lines – are thin lines consisting of alternate small-spaced
double dash with a longer space between them. It is used to
indicate repeated details of features. The double dash are
about .3 cm. Long with .1 cm. gap and the longer space is
.3 cm. Long.

12 Leader Lines – are thin lines drawn to 30, 45, or 60 degrees
with direction toward the center of arc or circle when extended.
Arrowheads of .3 cm. long and .1 cm. Wide touching the
features referred to, and horizontal shoulder of .5 cm. Long in
line at the mid-height of the figures and notes.

13. Construction Lines – are extremely light lines, so lightly done that
they can barely seen at a foot distance. Construction lines
are used for ‘’blocking-in’’ or constructing a drawing before
the final lines are made.

14. Border Lines – are the thickest lines ( extra heavy ) in a drawing . It
is used to enclose or frame a drawing.

17

Precedence of Lines:

In some views, coincidence of lines is likely to occur. When this happens the
following things maybe considered. It should always be considered that the outer
boundaries of a part is always a solid line. Since the external features are the
utmost importance, solid lines should take precedence over all other lines.

1. A full line or object line could cover an invisible line but an
invisible line could not cover a visible line.

2. Invisible or hidden lines take precedence over the center lines
although The center line may be extending .5 cm. Outside the
view.

3. When a center line and cutting-plane lines coincides on a drawing
the one that is more important for readability of the drawing
takes precedence over the other.

4. Break lines could be placed so that they do not spoil the
readability of –all view.

5. Dimension and extension lines must always be placed so as
not to coincide with the other lines.

ORDER OF PRECEDENCE

a. Visible or object line
b. Invisible or hidden line
c. Center line and cutting-plane line
d. Break lines
e. Dimension and extension lines
f. Section or cross-hatching lines

18

19

SELF- CHECK TEST
Direction: Draw the following alphabet of lines

1. Center Line
2. Dimension Line
3. Visible Line
4. Extension Line
5. Cutting Plane line
6. Invisible Line
7. Section Line
8. Long Break Line
9. Border Line
10. Short Break Line

20

INFORMATION SHEET NO. 1
Lathe machine

INTRODUCTION

The lathe is a versatile machine tool in which the
work is held and rotated. A cutting tool is moved along
the work to produce cylindrical shapes (Turning) or across
the work to form flat surfaces (Facing).

The speed of the work can be varied to suit
different diameters, operations or materials.

The movements of the tool can be combined
to produce a variety of cylindrical and flat surfaces.

Operations such as drilling, threading and
reaming may be performed on the lathe with the aid
of special equipment.

Several types of lathes have been designed
for special purposes. These lathes will be described
in other manuals of this series.

A general-purpose lathe is usually referred
to as a Center Lathe. It is the type most commonly
found in any workshop.

This manual will describe the features and
explain the operation of a center lathe.

Safety precautions for specific operations are
described in the text along with the one description of the
operation. Learn each operation before attempting to
carry it out. Safe work practices and habits result when
machines and materials are used correctly. Observe
the following important points when using lathes and
related equipment:

 Be tidy
 Wear suitable clothes
 Use correct tools and equipment
 Be careful
 Behave safely
 Wear adequate eye protection

21

 Use correct lifting methods
 Use serviceable tools.
FEATURES

The primary function of a lathe is to provide a means or removing metal by rotating the
work and feeding a cutting tool against the work.

There are three features of a lathe. These features provide:

 A support for the lathe components
 A means of holding and rotating the work
 A means of holding and moving the cutting tool.

SIZE OF THE LATHE

Lathes very considerably in size. The size of a lathe is indicated by the largest size
work that can be machined on it.

Generally two dimensions are stated. They are:

 The distance from the axis of the spindle to the top of the bed
- This indicates the largest diameter work that can be rotated in the lathe.

 The maximum distance between the centers.
- This indicates the longest work that can be held in the lathe.

22

A lathe designated 300 mm. x 300 mm. indicates that the lathe is capable of handling
work 300 mm. diameter and also work 900 mm. long.
NOTE:
For practical purposes the lathe could not hold a piece of work 300 diameter by 900
mm. long. The part of the lathe that holds and moves the tool reduces the clearance
between the spindle axis and bed. This feature is explained later in this manual.
Some lathe manufacturers designate the size of the lathe by the largest work diameter,
which can be revolved, and the length of the lathe bed.

23
TYPES OF LATHE MACHINES
Lathes are manufactured in a variety of types and sizes, from very small bench
lathes used in precision instrument and matchmaking industries, to gigantic lathes for
turning large steel shafts.
The different types of lathes are:
1. Bench Lathes
They are small engine lathes, which can be mounted on a bench or metal
cabinet, see Figure 1.

2. Center Lathe
It is the most common type of lathe in use, as shown in Figure 2. Its

versatility makes it suitable for machine shops that are engaged in small production
work.

24
3. Precision Lathe

It is smaller than the center lathe and is designed for the
production of small components for precision engineering, refer to Figure

The construction and principal parts of this type are similar to those
of the ordinary lathe machines.

4. Facing Lathe
It has a similar construction as the center lathe, refer to Figure 4.

The only difference is that the facing lathe is designed for machining short
workpieces of large diameters.

25

5. Copying Lathe

It is a center lathe equipped with an attachment, which guide the
turning tool to a template, as in Figure 5. It is suitable for turning
workpieces of complicated shapes in large quantities.

26

PARTS OF A LATHE

The major parts of a lathe are as
follows:

 The Bed
 The Headstock
 The Tailstock
 The Carriage
 The Feed Mechanism

27

1. THE BED

The bed is the part of the lathe
that provides support for the
other components. It is the
foundation in which all the
parts are fitted.

The bed is usually made from a
heavily ribbed rigid cast iron casting.

The top section is accurately machined
to form slides or ways to align the other
major parts. In some lathes these slides
are hardened to prevent wear.

1.1 FEATURES OF THE BED

Study the bed closely.

Note the solid construction providing
a rigid foundation for the
other parts.

Inspect the machined top section.
This provides the slide ways for the
carriage and tailstock.

Some lathes have flat slides; others
have raised vee ways for additional
accuracy.

The accuracy of the lathe depends to a large extent
on the condition of the bed slide ways.

Worn or damaged ways cannot be provided accurate
location or movement for the cutting tool.

Take care of the bed slide ways:

 Keep the slides clean

28

4.1 THE APRON

The apron is bolted to the front
of the saddle. It contains the
mechanism for moving
and controlling the carriage.

4.2 THE SADDLE

The saddle is the part of the carriage
that fits across and moves along the
bed, between the head and tailstock.

The cross slide is mounted on top of
the saddle and provides a cross
movement for the cutting tool. The
slide is at right angles to the bed
and is moved by means of a
screwed spindle fitted with a handle.

The compound rest is fitted on top and
to the front of the cross slide. The
compound rest may be swiveled
horizontally through 3600.

The top slide is fitted on top of the
compound rest. It provides a means
of supporting the tool post which
holds the cutting tool.

The top slide provides a limited
horizontal movement for the cutting tool.

By swiveling the compound rest, the
top slide may be set an angle to the
cross slide.

Normally the compound rest is set so that the top
slide is at right angles to the cross slide.

29

 Oil the slide frequently
 Never place tools or other articles

on the slides
 Avoid dropping pieces of metal

or equipment on the bed.

 Protect the bed with a wooden
board or block when fitting or
removing equipment from the
headstock spindle.

30

2 THE HEADSTOCK

The head stock is the lathe feature
that provides the means of holding
and rotating the work accurately.
It consists of housing fixed to the
left hand end of the lathe bed.

Bearings in the headstock support
and align the lathe spindle parallel
to the bed.

Gears or belts and stepped cone
pulleys are used to drive and vary the
speed of the lathe spindle.

The head stock spindle is a hollow
cylindrical shaft, which is supported
by bearings. Work holding devices
such as chucks drive plates and
faceplates are mounted on the right h
and end. This end is also bored to a
Morse standard taper to take the
headstock center.

The headstock also provides the
drive for the feed mechanism.

31

3 THE TAILSTOCK

The tailstock is used mainly
to support the right hand end
of the work. It may be moved
and clamped in position along
the bed.

The tailstock consists of a body
and a spindle.

The tailstock spindle is located
at the same height and parallel
to the headstock spindle.

The spindle may be moved in
and out of the body by means
of a hand wheel and threaded
spindle.

A clamping lever locks the spindle
in any position in the body.

The left hand end of the spindle is
bored out to a Morse standard
tapes to take the tailstock centre
and to hold various attachments
such as drills and chucks.

32

4 THE CARRIAGE

The carriage is the lathe feature that provides
the method of holding and moving the cutting
tool accurately. It consists of two major parts:

 The Apron
 The Saddle

5 THE FEED MECHANISM
Most centre lathes have some form
of power feed mechanism to provide
automatic movement to the cutting tool.
Power feed can be applied to both the
saddle and cross slide.
5.1 Quick Change Box
Located at the left have end of the lathe
bed is a variable speed gear box. This
box provides a means of changing the
speed of the feed shaft. The rate of feed
can be varied in relation to the revolutions
of the work to suit different materials
and operations.

33

5.2 Feed Shaft

Power is transmitted from the rear
end of the headstock spindle through
the quick change gear box to the feed
shaft located at the front of the lathe bed.

5.3 Lead Screw

Centre Lathes equipped with power
feed alsohave provision for screw-
cutting. A special threaded spindle
is mounted on the front of the lathe
bed adjacent to the feed shaft. It is
driven through the quick change gear
box.

On some small lathes the lead screw
and feed shaft are combined.

Both the lead screw and the feed
shaft pass through the apron of the carriage.
Controls on the apron enable the feed shaft
or the lead screw to be connected to the carriage.

34

5.4 Feed Lever

When the feed lever is engaged power is
connected from the feed shaft to the saddle and cross
slide. This provides automatic feeding for facing
and turning.

5.5 Lead Screw Engagement Lever

The lead screw is connected and released
from the carriage by means of half nuts.
The half nuts are operated by the lead
screw engagement lever on the apron.
These nuts are halved to enable the lead
screw to be engaged or disengaged easily.

An interlocking mechanism between the
levers prevents the lead screw and the
feed shaft from being engaged at the
same time.

The arrangement of gears in the feed
drive mechanism. provides a means of
reversing the direction of rotation
of the feed shaft and the screw. This
is done by moving the feed directional
lever to reverse.

35

SELF-CHECK: LATHE MACHINE

Select the best answer. Write only the letter of the correct answer on the
blank provided for.

1. A device attach to the spindle nose of the lathe machine when a piece of work
will be supported between centers.

a. Sleeve
b. Lathe dog
c. Face plate

2. DEVICES that directly hold the workpiece through the center is_____________.

a. Lathe center
b. Sleeve
c. Swivel center

3. ALL are type of tailstocks except_________.

a. Half center
b. Female center
c. Male center

4. Which of the following statement is true?

a. Lathe dog is a device that connects the workpiece
b. Live center are made of hard steel alloy
c. Sleeve serves as an adaptor

5. Which if the following tools are for testing center alignment?
a. Micrometer
b. Steel rule
c. Vernier caliper

36

INFORMATION SHEET NO. 2
SAFELY DEVICES AND PRECAUTIONS IN THE LATHE
Awareness of the safety practices in the shop is as important as operating a
machine. A trainee without proper safety attitudes has no place in the shop. He is not
only a menace to himself but to his fellow trainees.
Instructors in the shop are concerned about the safety and welfare of the
trainees, especially in the operation of machines. So they see to it that safety devices
are used and safety practices are observed.

LATHE SAFETY DEVICES
Modern lathes are provided with

guards, as in Figure 1, for belts and gearing.
These guards must always be kept closed
during operations. If these are open,
clothing might be caught up with the moving
gears, and physical injury may ensue.

Figure 1

1. Some of the special types of lathe
are provided with plastic hoods which
are placed over the cutting tool and the
workpiece. See Figure 2.

- The hood protects the operator’s eyes
from flying chips.

37

2. When machining materials that break
up into small chips, a vertical and adjustable
guard, as shown in Figure 3, is advisable for use.

3. If the type of guard, shown in
Figure 3, is not fitted in the lathe and to
the operation, safety goggles and eye
shades, see Figure 4 , must be used.

4. When machining materials that form ling
chips, the swarf must be removed with a
metal hook, as in Figure 5. It not advisable
to use hands, for swarfs are sharp and can
inflict deep and painful cuts.

38

5. A guard, see Figure 6, is used for long
bar or shaft if the end projects beyond the
lathe spindle.
- If the work is rotating, without a guard,

clothing can easily be caught up and may cause
accidents.

6. A guard, as in Figure 7, is placed
around the chuck to prevent the
cutting fluid form splashing out.

FIGURE 7

39

7. The holder, see Figure 8, for
the chuck key or T- wrench is
fitted on the head stock.

- The key should never be
left in the chuck after
using. Always use a
spring- loaded chuck
key which cannot be
left in the chuck

Figure 8

40

SELF-CHECK TEST

Without looking back on the previous page, answer the following questions.
write only the letter which stand for the correct answers. Use a separate answer sheet.

1. Plastic hood is placed in special types of lathes to protect the eyes from:
a. flying chips
b. flying debris
c. sky lab debris
d. loose parts
e. cuts

2. The safety device used when machining material that breaks up into
small chips is:

a. wooden guard
b. safety goggles
c. vertical and adjustable guard
d. plastic hood
e. rubber guard

3. The swarfs produced when machining in the lathe must be removed
with the use of:

a. wooden hook
b. rubber guard
c. plastic hood
d. metal hood
e. taps

4. Scattered swarfs on the floor can easily cause physical injuries like:
a. brain contusion
b. cuts eh fore-arm
c. broken skull
d. cancer
e. broken arms

5. The eye protector used when turning material which easily breaks up into small
chips is:

a. plastic hood
b. vertical and adjustable guard
c. sun glasses
d. rubber mask
e. safety goggles

41

INFORMATION SHEET NO. 3
TURNING SAFETY RULES

GENERAL SAFETY DO NOT

DO 1. Do not run in the workshop.
2. Do not throw things.
1. Use your common sense. 3. Do not touch any equipment or
2. Ask if in any doubt. machine unless authorized to do so.
3. Always use the correct tools for the job. 4. Do not walk away and leave your
machine running.
4. Replace tools that are worn or 5. Do not direct compressed air at
damaged. yourself or workmates. It can kill.
5. Keep tools and equipment in racks or
on work table when not 6. Do not leave crane hook over
in use. machine area when not in use.
6. Keep gangways and machine area
clear.

MACHINE SAFETY

Do DONOT

1. Keep machine clean and in good 1. Do not fool about on a machine.
condition.
2. Ensure you know how to stop your 2. Do not attempt to operate the
machine, before starting it. machine, until you are sure you
understand the operation.
3. Switch off machine immediately, if 3. Do not attempt to change the
anything goes wrong. direction or speed of the spindle whilst
it is in motion.
4. Keep machine and surrounding area 4. Do not mount or use a cracked or
tidy. damaged tool.
5. Check oil levels before first starting 5. Do not tamper with the machine.
machine.
6. Check direction of chuck rotation before
starting.
7. Replace any worn or damaged nuts,
bolts etc.
8. Switch off machine at the mains at the
end of each shift.
9. Remove the chuck key before starting
rotation of chuck.

42

PERSONAL SAFETY

Do DO NOT

1. Report an accident, however small, 1. Do not wear rings, watches etc.
immediately.
2. Wear approved safety glasses. 2. Do not keep sharp tools (scribers
etc.) in overall pockets.

3. Wear safety shoes. 3. Do not remove sharp guards unless
machine is stopped.

4. Use barrier creams provided. 4. Do not wash hands in coolant
5. Wear your overalls buttoned up.
5. Do not remove swarf with bare
hands, use a rake or brush.

6. Rolls sleeves up, or button the cuffs. 6. Do not manually lift heavy equipment.

7. Keep hair short or wear a cap. 7. Do not touch revolving chucks or
workpieces.
8. Ensure all guards are in position 8. Do not use cracked or chipped tools.
before starting machine.

9. Check that work area is clear before 9. Do not use files, scrapers, etc.,
starting machine. Keep the floor around without handles.
machine clean &free of greases & oil,
which could cause falls. 10. Do not lean on the machine. Stand
10. Ensure everything is secure before erect, keeping your face and eyes away
starting machine. from flying chips.

11. Ensure feed mechanism is in
neutral position before starting machine.

12. Use the correct type of sling,
correct S.W.L. and ensure it is not worn
or damaged.
13. Be careful of burrs and sharp
edges.
14. Use the correct size spanners at all
times.
15. Ensure hammer heads are not
loose.
16. Stand clear when lifting workpieces
or equipment by crane.

43

LATHE SAFETY PRECAUTIONS

1. Make sure that long swarfs, Figure 9,
are not scattered on the floor. Physical
injuries like cuts on the legs or arms are
likely to happen.

2. Use goggles or other protections for the
eyes when turning materials that easily
breaks up into small chips. Refer to Figure 4.

3. Always remove the chuck key when Figure 10
it is not in use, see Figure 10.

4. When turning, keep the hands away from the dangerous parts of the workpiece
and machine.

5. Never remove chips with compressed air. Flying particles can easily get into the
eyes. Cutting oil and chips are toxic

6. Wear tightly fitted working clothes. Give particular attention to sleeves, as these
can easily be caught up by rotating workpiece and work holding devices.

7. Shut off the machine before taking measurements of any kind & before leaving it.

8. Avoid playing in the working area.
9. Don not take heavy cuts on long slender pieces. This could cause the work to
bend & fly out of the machines.

44

SELF-CHECK: TURNING SAFETY RULES
Check your mastery by answering each statement either true or false.

1. While turning, you can wash your hand in the coolant.

2. Measurements can be taken while lathe machine is in operation.

3. Operate the lathe only when you understand the operation.
4. Floor area around the machine should be clean and free from grease and oil.
5. It is not advisable to wear rings and watches while machining.
6. Before starting a machine, you should know how to stop it.
7. There is no need to check oil levels before starting the machine.

8. Minor accident may not be reported to the instructor.

9. Sharp tools can be kept in the pocket.

10. Feed mechanism should be in neutral position before starting the machine.

45

INFORMATION SHEET No. 4

MOUNTING WORK BETWEEN CENTERS

There are many ways and methods by which workpiece can be mounting in a
lathe for machining. One of which is mounting them between centers. This method of
mounting work in the lathe is one of the most commonly used, especially when the
workpiece is long and both ends need to be supported. The centers provide the
required parallelism to workpiece like shafting and others or related types.

This method of mounting would also provide a bigger space to perform several
operations in the workpiece. However, this method cannot be accomplished without
first knowing the tools, attachments and work holding devices to be used in which some
are discussed and illustrated in the following pages.

TOOLS AND HOLDING DEVICES USED IN MOUNTING WORK BETWEEN
CENTERS

1. FACEPLATE – Is a device attached to the spindle nose of the lathe machine
when a piece of work will be supported between centers. It is machined so that it
will be square with the lathe centers. It is machined so that it will be square with
the lathe centers when mounted on the spindle.

Three types of face plates are shown in Figure 1.

Figure 1. Types of Faceplates

46

2. LATHE DOG – Is a device that connects the workpiece to the faceplate when
hold between centers. It is clamped on one end of the stock to provide the
necessary support. Three common types of lathe dogs are shown in Figure 2.1,
2.2 and 2.3

With safety screw with square-head

screw

Figure 2.1 Bent- tails Standard dog

Figure 2.3 Clamp- Type dog

47
3. SLEEVE – Serves as an adapter to receive the smaller taper of lathe center and

drill chucks when lathes have a very large taper hole in the spindle. The out de
taper of the sleeve fits the taper bore of the spindle, and the internal taper is
made to fit the taper shank of the lathe center (see Figure 3).

Figure 3. A sleeve
4. LATHE CENTERS – are devices that directly hold the workpiece through the

center holes drilled on both ends. They are attached to the headstock and tail-
stock spindles. See Figures 4.1 and 4.2 for the illustrations of the lathe centers
(see next page).
4.1 HEADSTOCK OR LIVE CENTER – May be made from soft steel alloy. It is

attached to the headstock spindle and rotates with the work.
Live or Headstock Center

Types of Tailstock or Dead Centers
a. Large Point Center

b.. Half Center

c. Female Center

d. Swivel Center

48
METHODS OF CHECKING CENTER ALIGNEMENT
Workpiece that require accurate turning or facing between centers need a
precise alignment of centers. Thorough check- up then of the centers alignment is
necessary before any machining operation takes place. This ensures an accurate finish
on the workpiece and eliminates waste of materials. To check the alignment of centers,
the following methods are recommended.
1. Checking centers visually by bringing the center points together. (See Figure 5.
See next page)

Figure 5. Checking the Center Alignment with two centers

49
2. Checking the witness lines on the back of the tailstock for alignment. See Figure

6.

Figure 6. Checking the Center Alignment
When workpiece require close tolerance, more precise methods of checking
center alignment should
be followed.
1. Make a light trial cut a few millimeters across the workpiece, check the diameter
at each end of the cut with a micrometer. See Figure 7.

Figure 7. Checking the Alignment of Center by making a trial cut at the end of the
workpiece.

50

SELF-CHECK: MOUNTING WORK BETWEEN CENTERS

Select the best answer. Write only the letter of the correct answer on the blank
provided for.

1. What part of the carriage that fits across and moves along the bead?

a. Apron
b. Tail stocks
c. Saddle

2. The compound rest can be swiveled horizontally to how many degrees?

a. 90o
b. 240o
c. 360o

3. What part of the lathe that is made of heavily ribbed rigid cast iron casting?

a. Bed
b. Saddle
c. Head stock

4. All of the following are parts of the tailstock except.

a. Head stock
b. Tail stock
c. Bed stock

5. Part of the lathe machine that provide the means of holding and rotating the work
accurately.
a. Head stock
b. Tail stock
c. Bed stock