Machining
Module 5: Lathe Setup and Operations
(Part 1)
PREPARED BY
Curriculum Development Unit
August 2013
© Applied Technology High Schools, 2013
ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 2
Module 5: Lathe Setup and Operations
(Part 1)
Module Objectives Upon the completion of this module, the student will be able to:
Identify the main machining operations using a lathe machine.
Describe the logical sequence of the main machining operations.
Set the cutting tool to the center of the machine.
Set the cutting depth using graduated collars.
Describe and Implement the main check list before starting a lathe
machine.
Perform a facing operation using a lathe machine
Perform a center drilling operation using a lathe machine
Module Contents Topic Page No.
Introduction 3
1 Practical project 3
1.1 Machining procedure 4
2 Machine Setup 8
3 Hints on chuck work 11
4 Lathe machine safety 12
5 Lathe machine check list 15
6 Lathe operations 16
References 27
ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 3
Introduction
Lathe could be used for many operations to produce different shapes to the
required size. In this course the machine operations will be covered through
an on going practical project.
1. Practical Project
The practical project is to use the lathe machine tool to make the part
shown below. Fig. 5.1
Fig. 5.1
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Module 5: Lathe Setup and Operations (Part 1) 4
1.1 Machining Procedure
To machine the part shown in Fig. 5.1, the following sequence of operations
is suggested:
A piece of Aluminum ϕ 25 x 80 mm will be provided.
Step 1:
Cut the two ends of the workpiece to make it flat, straight and to reduce
the workpiece length to the required size. This operation is called Facing.
Fig. 5.2 Facing operation Step 2:
Drill a center hole on one end of the workpiece.
Center holes are used either to be used as a seat for the tailstock centers
which may support the workpiece or as start and guide for drilling
operation. This operation of making small conical spot on the end of the
workpiece is called center drilling. Fig.5.3
Fig. 5.3 Center drilling
ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 5
Step 3:
Reduce the diameter from 25 to 12 mm to a length = 18 mm as shown.
This is called Parallel Turning. Fig. 5.4
Fig. 5.4 Parallel turning
Step 4:
Cut the tapered shape as shown.
The operation of increase or decrease of diameters is called taper turning.
Fig. 5.5
Fig. 5.5 Taper turning
ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 6
Step 5:
Cut the groove shown, in its correct position (see the drawing) and to the
required size.
This operation is called external groove or external recessing. Fig. 5.6
Fig. 5.6 Recessing (grooving operation)
Step 6:
Cut the thread shown. Thread is the process of cutting spiral or helical
shapes. Fig. 5.7
Fig. 5.7 Threading operation
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Module 5: Lathe Setup and Operations (Part 1) 7
Step 7:
Drill at the center of the workpiece to the dimensions shown.
Fig. 5.8
Fig. 5.8 Drilling operation Step 8:
Use a piece of sand paper (abrasive) to polish the work.
Note:
This sequence of operations is just a suggestion. Some operations must be
done in a certain sequence but some other operations don’t need to be in
sequence.
Examples:
You shouldn’t start a taper turning before reducing the diameters to the
required size by parallel turning.
You should not do polishing before finishing the work.
You can’t do drilling before center drilling.
ATM 412
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ATM 412
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ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 10
Fix the handwheel by one hand and rotate
the collar by the other hand to adjust the
zero on the graduation collar to the fixed
line on the compound or cross slide (Fig.
5.13). Set zero on the graduated collar
means touching the surface from which
you are going to take the correct value for
depth of cut.
2. All depths of cut must be made by
feeding the cutting tool toward the
workpiece while the collar is released.
3. If the graduated collar is turned past the
desired setting, it must be turned
backward a half-turn and then fed into the
proper setting to remove the backlash (the
play between the feed screw and the nut).
4. Never hold a graduated collar when
setting a depth of cut. Graduated collars
with friction devices can be moved easily if
held when a depth of cut is being set.
Fig. 5.13: Setting the
graduated collar to zero
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Module 5: Lathe Setup and Operations (Part 1) 11
3. Hints on chuck work:
If possible, all diameters should be machined on a workpiece in one setup before it is removed from a three or four jaw chuck. If the work is removed and then replaced in the chuck for further machining, it will probably not run true, or it will take some time to bring it back to the original trueness. Since we need to remove and mount the workpiece several times in our course, so a step of making a center hole on the face of the workpiece is done at the beginning to help in mounting the workpiece properly every time we need to work on it.
Tighten the chuck jaws around the most rigid part of the work to prevent distortion of the workpiece
If the work projects more than three times the diameter of the stock, it should be supported by a revolving tailstock center or steady rest.
Never grip the work on a diameter smaller than the diameter to be machined unless absolutely necessary.
Tighten the chuck securely so that the workpiece is not moved into the chuck by the pressure of the cut.
Always set the toolbit point on center. If the toolbit is set too low, the work may be bent.
Position the toolpost on the left side of the compound rest. Move the carriage until the toolbit is at the extreme left end of
travel and the toolbit is off the work surface. Rotate the chuck one turn by hand to see that the jaws do not
strike the compound rest. Never use an air hose to clean a chuck Never leave a chuck wrench in a chuck.
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Module 5: Lathe Setup and Operations (Part 1) 12
4. Lathe Safety
In addition to the general safety rules in machine shop described in module
2, the following points should be considered during the lathe operation:
Do not attempt to operate a lathe until you know the proper procedures
and have been checked out on its safe operation by your instructor.
Never attempt to operate a lathe while
your senses are impaired by medication.
Fig. 5.26
Fig. 5.26: Medication
Fig. 3.27: Safety overall.
Dress appropriately; Remove any
necklaces, other jewelry, wristwatch, or
rings. Secure any loose-fitting clothing
and roll up long sleeves. Wear an apron
or a properly fitted shop coat, safety
glasses are a must. Fig. 5.27
Always be sure that the cutting tool and
the workpiece are properly mounted
before starting the machine.
Turn the chuck by hand to be sure there
is no binding or danger of the work
striking any part of the lathe.
Metal chips are sharp and can cause severe cuts. Do not try to remove
them with your hands. When they become “stringy” and build up on the
tool post, stop the machine and remove them with pliers.
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Module 5: Lathe Setup and Operations (Part 1) 13
Do not permit small-diameter work
to project too far from the chuck
without support from the tailstock.
The work will be tapered or worse,
spring up over the cutting tool and
/or break. Fig. 5.28.
Fig. 5.28: Small diameter work should not project too far from
the chuck
Do not run the cutting tool into the
chuck. Check any readjustment of
the work or tool to make sure there
is ample clearance when the cutter
has been moved leftward to the
farthest point that will be machined.
Fig. 5.29
Fig. 5.29: Ample clearance between the chuck and the
cutting tool
Before repositioning or removing
work from the lathe, move the
cutting tool clear of the work area.
This will prevent accidental cuts on
your hands and arms from the cutter
bit. Fig. 5.30.
Fig. 5.30: move the cutting tool clear of the work area
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Module 5: Lathe Setup and Operations (Part 1) 14
Always remove the key from the
chuck. Make it a habit to never let go
of the key until it is out of the chuck
and clear of the work area. Fig. 5.31.
When doing filing on the lathe, make
sure the file has a securely fitting
handle.
Fig. 5.31: Always remove the key
from the chuck
Tools must not be placed on the
lathe ways. Use a tool board or place
them on the lathe tray. Fig. 5.32.
If any odd sounding noise or
vibration develops during lathe
operation, stop the machine
immediately. Get help from your
instructor.
Fig. 5.32: Tools must not be placed on the lathe ways.
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Module 5: Lathe Setup and Operations (Part 1) 15
5. Lathe Machine Check List:
The ‘checkout procedure’ for the lathe
should include the following actions:
Clean and lubricate the machine.
Fig.5.33
Be sure all guards are in position and
locked in place before start the
machine. Fig.5.34
Turn the spindle over by hand to be
sure it is not locked.
Move the carriage along the ways.
Therefore should be no binding.
Check cross-slide movement. If there
is too much play, adjust gibs,
(Adjusting screws are used to adjust
the movement of the slides of the
machine). This is applicable for most
of machine’s slides Fig 5.35
Adjust the drive mechanism for the
desired speed and feed.
If the tailstock is used, check it for
proper alignment. Fig. 5.36
Clamp the cutter bit in the appropriate
tool-holder and mount it in the tool
post. Do not permit excessive
compound rest overhang, since this
often causes tool ”chatter” and results
in a poorly machined surface.
Mount the work. Check for adequate
clearance between the work and the
various machine parts.
Fig. 5:33: Clean and lubricate
the machine.
Fig. 5.34: Machine guards are in
place.
Fig. 5.35: Adjusting screws s are used to tighten and release the movement of the cross slide.
Fig. 5.36: The tailstock must be
aligned to zero.
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Module 5: Lathe Setup and Operations (Part 1) 16
6. Lathe operations
6.1 Facing
Facing is to remove a small amount of material (around 1 – 2 mm) from the
end of the workpiece to produce smooth and true face and also to bring the
workpiece to the desired length. The facing operation and the cutting tool is
shown below in fig. 5.37
Fig. 5.37: Facing operation and the cutting tool
Fig. 5.38: The facing tool must be placed on the centerline of the workpiece and the
tip of the tool should meet the end of the work piece at a slight angle
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Module 5: Lathe Setup and Operations (Part 1) 17
6.1.1 Practical Task 1:
a) To do facing on the free end of the workpiece.
b) To reverse the work and do facing on the other end of the workpiece to
bring the final length to 78 mm.
Blank part dimensions: Ф 25 X 80 mm. Fig. 5.39 (a)
Finished Part: as shown in Fig. 5.39 (b)
Tool: Right hand tool.
Material: Aluminum
Fig. 5.39 (a): Before facing
Fig. 5.39 (b): After facing ( length is
reduced)
No. Setup and production steps description 1. Read, understand fully and follow
all the safety regulations.
As always, wear safety glasses
and keep your face well away
from the work. Make sure the
power feed lever is disengaged,
the compound rest is set at zero
angle and the carriage’s lock is
not tightened down. Fig. 5.40.
Fig. 5.40: Carriage lock
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Module 5: Lathe Setup and Operations (Part 1) 18
2.
Mount the workpiece securely in a
chuck and make sure to remove
the chuck key.
Use a three jaw universal chuck to
avoid the effort to true up the
work in the chuck.
To get the work properly
centered, close the jaws until they
just touch the surface of the work,
then twist the work piece in the
jaws to seat it; then tighten the
jaws. It's good practice to tighten
the jaws from all 3 chuck key
positions to ensure even gripping
by the jaws. Fig. 5.41
Fig. 5.41: Workpiece mounted in three jaw chuck
3.
Set the work in the chuck so that
no more than three times its
diameter extends beyond the
chuck jaws. Fig. 5.42
Fig. 5.42
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Module 5: Lathe Setup and Operations (Part 1) 19
4.
Clamp the cutting tool in the tool
post. Set up the facing cutting tool
to the height of the dead center
(on the tailstock) and turn the tool
post so that the tip of the cutting
tool will meet the end of the work
piece at a slight angle. Fig. 5.43
The tool bit should be clamped in
the tool holder with minimum
overhang. Otherwise, tool chatter
and a poor surface finish may result.
Fig. 5.43
5. Advance the carriage toward the
chuck until the tool is about even
with the end of the workpiece. Fig.
5.44,
Make sure that the compound rest
is not all the way at the end of its
travel towards the chuck. The
carriage is then locked in position.
Fig. 5.44 6. Set the rotational speed relative to
the diameter of the workpiece.
7. Rotate the chuck by hand to be
sure it is not locked then return
the chip guard (cover) over the
chuck.
8. Start the machine
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Module 5: Lathe Setup and Operations (Part 1) 20
9. The usual practice is to start from
the center and feed outward (both
directions are correct).
Rotate the cross slide handwheel
clockwise until the cutting tip
reaches the center of the
workpiece. Use the compound rest
handwheel to advance the tip of
the tool until it just touches the end
of the work piece (Fig. 5.45). Use
the cross slide handwheel to back
off the tool until it is beyond the
diameter of the work piece.
A rounded “nubbin” (remaining
piece of unmachined material) will
result if the tool is slightly above
center. Fig. 5.46
A square-shoulder “nubbin”
indicates that the cutting tool is
below center. Fig. 5.47
With the cutting tool on center a
smooth face will result from the
cut.
This cutting sequence is repeated
until the part has been leveled
(faced off).
Fig. 5.45
Fig. 5.46
Fig. 5.47
10. Stop the machine
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Module 5: Lathe Setup and Operations (Part 1) 21
11. Release the carriage and move it
away to the right.
Fig. 5.48
Fig. 5.49
12. Measure the total length of the
workpiece.
13. Reverse the workpiece in the
chuck.
14. Subtract the finished length from
the measured length this is equal
to the amount you want to remove
by the second facing operation.
15. Reverse the compound rest to its
permissible length then bring the
carriage back in front of the
workpiece and lock it.
16.
Move the compound rest
handwheel until the cutting tip just
touches the surface of the free end
at the center of the workpiece (Fig.
5.48). Adjust the compound rest
graduated collar (fig. 5.49) to zero
and then start the machine.
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Module 5: Lathe Setup and Operations (Part 1) 22
17. Set the depth of cut by using the
graduated collar on the compound
rest. 0.5 mm could be removed
every cut.
Fig. 5.50
18. Crank the cross slide backside until
the tool clears the work.
Reverse the cross slide movement
to bring the cutting tool to the
center of the workpiece again.
This sequence of cutting
mentioned in steps 17 to 19 is
repeated until you reduce the
length of the workpiece to 78 mm
Fig. 5.50. (Stop the machine at
intervals to take measurements)
19 20
21. Stop the machine, release and
move the carriage to the right side
of the machine, near the tailstock.
Check the length by the vernier
caliper.
Fig. 5.51
22. Use a hand file to break the sharp
edge as shown in fig. 5.51
23. Remove the workpiece.
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Module 5: Lathe Setup and Operations (Part 1) 23
6.2 Center drilling
Center hole is a short combined hole of both straight and tapered shape,
drilled into the ends of the part to allow the conical points of the lathe
centers to fit snugly into it. Lathe center is mounted on the tailstock to
support long workpiece on its free end when the part is held on the lathe
chuck.
Center drills are also used to set a true center point as a guide and start
point for drilling operation. Fig. 5.52
Note: This operation should not be done before facing.
Fig. 5.52: Center drill
The tool used is called a center drill (combination of drill and countersink).
Regular center drills are made with a 60 degree angle on the pointed end.
Center drill s are available in different sizes (0,1,2,3,….. etc) to suit
different diameters of work. Table 5.1
Center drill
Size Workpiece diameter in (mm)
1 3 - 8
2 9.5 – 12.5
3 15 – 20
4 25 – 40
5 50 - 75
6 75 - 100
7 100 - 125
8 150 and over
Table 5.1 – Center Drill Sizes
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Module 5: Lathe Setup and Operations (Part 1) 24
6.2.2 Practical Task 2:
Objective: To drill a center hole on the free end of the workpiece provided.
Blank part dimensions: Ф 25 X 78 mm
Finished Part: as shown in Fig. 5.54
Tool: Center drill. Size 4.
Material: Aluminum
Fig. 5.53: Before center drilling
Fig. 5.54: Finished part
No.
Setup and production steps description
1. Read, understand fully and follow
all the safety regulations.
As always, wear safety glasses
and keep your face well away
from the work since this operation
will throw off hot chips and/or
sharp spirals of metal.
Check the lines on the back of the
tailstock to see that they are
aligned. Correct if necessary.
Fig. 5.55
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Module 5: Lathe Setup and Operations (Part 1) 25
2. Mount the workpiece in a three jaw
chuck. No more than three times
the diameter should extend
beyond the chuck jaws.
Fig. 5.56
3. Mount a drill chuck on the tailstock
spindle. Mount the correct center
drill, in the drill chuck. A center
drill BS 4 is suitable for 25 mm
diameter workpiece. Fig. 5.55
4.
5.
The tailstock has two lock arms.
Long one is to hold the tailstock to
the bed of the machine and the
other short one is to stop the
movement of the tailstock spindle.
Fig. 5.56 and 5.57.
Release the tailstock lock and
advance the tailstock until it
reaches near the workpiece and in
front of the work free end. Lock
the tailstock at this position. Make
sure the tool post is far enough
from the chuck. Fig. 5.57
Set the rotational speed to
approximately 1200 to 1500 RPM,
then start the machine.
Fig. 5.57
Fig. 5.58
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Module 5: Lathe Setup and Operations (Part 1) 26
6.
7.
Advance the tailstock spindle
slowly by rotating the handwheel
clockwise to feed the tool into the
work (fig. 5.58), (make sure the
lock of the spindle is released).
The suitable depth is to feed the
tool to approximately more than
half of the countersink (tapered
part) of the tool head. Fig. 5.59
Reverse the headstock handwheel
until the cutting tool is free from
the workpiece, then stop the
machine. Fig. 5.60
Release the lock of the tailstock
and draw it back to it’s position on
the right side of the machine.
Fig. 5.59
Fig. 5.60
8.
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Module 5: Lathe Setup and Operations (Part 1) 27
References
1. Technology of Machine Tools. Seventh Edition, McGraw-Hill
Companies,
2. Machine shop operations and setups, 4th edition, Lascoe nelson
Porter.
3. Machine tool and Manufacturing technology, Steve F. Krar, Mario
Rapisarda, Albert F. Check., Delmar Publishers.
4. en.wikipedia.org/wiki/Machining
5. http://www.mini-lathe.com
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Module 5: Lathe Setup and Operations (Part 1) 28
Student’s notes ..................................................................................................................................................
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ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 29
Worksheet
1. List the main lathe machine operations required to make the part
shown below:
No. Name of the part
1
2
3
4
5
6
ATM 412 – Machining
Module 5: Lathe Setup and Operations (Part 1) 30
2. Define the term “facing operation”?
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3. For what purposes do we need to do center drilling?
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4. What is the function of the graduated collars?
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5. Mention one method used to bring the cutting tool tip to the center of
the machine?
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