ATM-412 Machining M5 - Miss Hanna's Classroom :)misshannahsclassroom.weebly.com/.../atm-412_machining_m5.pdfATM 412 – Machining Module 5: Lathe Setup and Operations (Part 1) 3 Introduction

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



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



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



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



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



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.

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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



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.



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.



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



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.



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.



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



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



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



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



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



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.



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.



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



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



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



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.



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



Student’s notes ..................................................................................................................................................

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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



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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Documents

ATM-412 Machining M5 - Miss Hanna's Classroom :)misshannahsclassroom.weebly.com/.../atm-412_machining_m5.pdfATM 412 – Machining Module 5: Lathe Setup and Operations (Part 1) 3 Introduction