Recessing

Operation Title: Recessing
Purpose:
Condition or Situations for the Operation

External recessing (Figure 1a), is the operation of machining a smaller diameter on a workpiece
for a specified length. Internal recessing (Figure 1b), is the machining of a larger diameter for a
specified length inside a hole. Recesses may have squared or rounded corners depending on where
they will be used. Recesses are produced especially on parts of a machine which require material
fillings.

Figure 1. Example of External and Internal Recessing

TOOLS, EQUIPMENT AND MATERIALS

1. Tools
1.1 Recessing tools
1.2 Toolholder
1.3 Vernier Caliper
1.4 Outside Micrometer
1.5 Four Jaw Independent Chuck
1.6 Center or Tool Gauge
1.7 Hermaphrodite Caliper
1.8 Steel Rule
1.9 Safety Goggles
1.10 T-Wrench
1.11 Hook Rule

2. Materials
2.1 1 pc Ø 6.35 x C.R.S.
2.2 1 pc Ø x 34 C.R.S.
2.3 1 pc 25.4 Ø x 19.0 C.R.S.
2.4 MS Drawing Nos. 1 Ø 8 and 1 Ø 9

3. Equipment
3.1 Lathe machine

Procedure

Task No. 1 – Turning an external recess of a shaft

1.1 Study the drawing of the shaft
- Refer to MS drawing

1.2 Clamp the workpiece in a chuck
a. Clean chuck jaws and check if they are properly centered
b. Clamp the workpiece providing minimum overhung. See Figure 2.

Figure 2. Mounting the workpiece in a chuck

1.3 Select and set-up cutting tool
a. Choose the right design of outing tool
b. Clamp and set-up cutting tool, Figure 3. Use a center gauge.

Figure 3. Setting-up tool using center gauge
1.4 Set-up speed and feed of machine

a. Select speed and feed of machine based from the material of the workpiece
b. Choose the nearest speed on the machine date place
c. Set the speed with lathe controls, Figure 4.

Figure 4. Setting up machine speed and feed
1.5 Set the position of the too

a. Wind the cross slide so that the tool is approximately 0.5mm clean of the workpiece
diameter.

b. Align the required measurement on the rule to the end of workpiece, Figure 5. the steel
should be parallel to the workpiece

Figure 5. Setting up cutting tool to the correct position
c. the depth of a vernier caliper is also use to set-up the position of the tool Figure 6.

Figure 6. Using the Vernier Depth Bar to set-up tool position
1.6 Turn recess to specification

a. Start the spindle and let the tool touch the workpiece diameter
b. Set the cross slide micrometer collar to zero
c. Turn on coolant and feed in the tool to a depth 0.1mm less of the specified depth of

recess, Figure 7. Use hand feed.

Figure 7. Setting up the depth of cut.
d. Stop the spindle and check the diameter of work with a micrometer. See Figure 8

Figure 8. Measuring external diameter with micrometer
e. Check the length between end of workpiece and start of recess, figure 9.

- the saddle may be move to adjust the length if require

Figure 9. Checking length using a steel rule.
f. engaged the automatic feed, then allowed the tool to cut along the workpiece.
g. Disengaged feed when the tool is about 0.5mm from the required length. See Figure 10.

- Finish the length of recess using hand feed.

Figure 10 Cutting an external recess
h. Withdraw the tool from the workpiece and bring it back on the starting point to take the

finish cut, Figure 11.
Remarks: Refer to figure 10. Show that the cutting tool is at the starting point.

Figure 11. Setting-up the tool take finish cut.
i. stop the spindle and check length of recess. See Figure 12.

Figure 12. Checking dimensions of recess using a Vernier Caliper.
j. Check the diameter of recess with an outside micrometer. Refer to Figure 8.
Task No. 2 – Turning the recess with an outside micrometer. Refer to Figure 8.
2.1 Study the drawing of the marking gauge flange

- Refer to MS Drawing No. 108
2.2 Clamp the workpiece in a chuck

a. Clean chuck jaws and check if they are properly centered.
b. Clamp the workpiece providing minimum overhang like in Figure 14.

Figure 14. Clamping the workpiece in a chuck
2.3 Select and set-up cutting tool.

a. Choose the correct design of recessing tool.
b. Clamp and set-up recessing tool, Figure 15.

Figure 15. Setting-up tool using a center gauge.
2.4 Set spindle speed and feed of machine

a. Select speed and feed from the table
b. Locate the nearest speed and feed form the machine data plate
c. Set the speed and feed with lathe controls. Refer to Figure 14.
2.5 Set the position of the tool
a. Wind the cross slide so that the tool is approximately o.5mm clear of the workpiece
diameter.
b. Mark out the length of recess using a steel rule or a vernier caliper. See Figure 16.

Figure 16. Laying out length of recess using a vernier caliper.
2.6 Turn recess to specification

a. Start the spindle and le the tool touch the workpiece diameter. Figure 17.

Figure 17. Positioning tool to set-up micrometer collar to zero.
b. Set the cross slide micrometer collar to zero.
c. Turn on coolant and feed in the tool to a depth 0.1mm less of the specified depth of
recess, Figure 18.

Figure 18. Rough turning of the recess

d. Stop the spindle and check the diameter of recess with a micrometer. Refer to Figure
e. Check the length of recess using the steel rule or a vernier caliper. Refer to figure 9.
f. Re-start the spindle, engage the automatic feed and allow the tool to cut along the
workpiece.
g. Disengage feed when the tool is about 0.5mm from the required length. Refer to figure
10.

- finish the length of recess using hand feed.
h. Withdraw the tool from the work and bring it back to the starting point and take finish
cut.
i. Stop the spindle and chuck dimensions of recess. Refer to Figure 8 and 10.

Task No. 3 – Turn the recess of the marking gauge shaft
3.1 Study the drawing of the marking gauge shaft
- Refer to MS drawing No. 109.
3.2 Clamp the workpiece between contours, Figure 19.
- Protect finished diameter with soft metal stripes or shims.

Figure 19. Mounting the workpiece between centers
- The workpiece may be held also, in the chuck and center, see figure 20.

Figure 20. clamping the workpiece in a chuck and center
3.3 Select and set-up cutting tool

a. Choose the correct design of recessing to be used
b. Clamp and set-up tool, refer to figure 3
3.4 Set-up spindle speed and feed of machine
a. Select speed and feed form the table
b. Locate the nearest speed and feed of machine speed plate
c. Set speed and fee with in the controls, refer to figure 4.
3.5 Se the position of the tool
a. Wind the cross slide so that the tool is approximately 0.5mm clear of the workpiece
diameter.
b. Mark out the length of recess using a steel rule. See Figure 21.

Figure 21 Laying out Length of recess
c. Position the tool on the scribed line, figure 22.

- a fine line may be made on the diameter using the point of the tool, Figure 22.

Figure 22. Marking out a fine line
3.6 Turn recess to specification

a. Start the spindle and let the tool touch the workpiece diameter
b. Set the cross slide micrometer collar to zero
c. Turn on coolant and feed in the tool to a depth 0.1mm less of the specified depth
recess.
- Use hand feed
d. Stop the spindle and check the diameter of recess with an outside micrometer. Refer
to Figure 8.
e. Check the length of recess using a steel rule or a vernier caliper. Refer to Figure 9.
f. Re-start the spindle , engage the automatic feed, that allow the tool to cut along the
workpiece.
g. Disengage feed when the tool is about 0.5mm form the required length of recess

- Use hand feed to turn full length of recess

h. Withdraw the tool form the work and bring back on the starting point to take the finish
cut, see figure 23.

Figure 23. Turning recess to specification
a. Stop the spindle and check dimensions of recess. Refer to Figure 8 and 10.
Task No. 4 – Turning an internal recess
4.1 Study the drawing of the workpiece
- Refer to MS drawing
4.2 clamp the workpiece in the chuck
- Provide minimum overhead
4.3 Select and set up cutting tool
a. Choose the form of tool to be used based on the specification
- Be sure that the cutting edge is sharp
b. Set up the tool on center
- Use minimum overhang

Figure 24 Correct set-up of an internal cutting tool
4.4 Select and set-up speed and feed

a. Set speed and feed with lathe controls
- Read possible values on the machine data plate
-----------------------------------------------------------------------------------

SAFETY NOTE
- Wear safety goggles
- Use guards
-----------------------------------------------------------------------------------
4.5 Turn the recess
a. Start the spindle and wind the tool to touch the surface of hole

Figure 25. Setting-up the tool into the hole.

b. Set the cross slide scale to zero
c. withdraw the tool from the hole and wind it to touch the end of workpiece, Figure 26 (see next
page)
- Stop the spindle and lock the saddle

- Note down the width of tool in preparation for the setting of the distance of recess through
compound rest
- Set the compound rest zero

Figure 26. Setting- up the tool against the end of the workpiece.

Figure 27. Positioning the tool into the hole
e. Set-up the distance of recess plus the tool width on the compound rest scale. See Figure
28.

Figure 28 Positioning the tool to cut the recess

f. Star the spindle and feed in the tool to the correct depth of recess using the cross slide
scale (on the reverse the operator).

Figure 29 Turning an internal recess
g. Feed in the tool to the correct width of recess using the compound rest.

NOTE:
The width of the tool should be smaller then the specified width of recess

a. Withdraw the tool from the hole by moving the cross slide away form the workpiece
b. Stop the spindle
c. Check length of recess using a hook rule. See Figure 30

CALL INSTRUCTION FOR CHECK-UP

Precautions Figure 30 Checking an internal recess
IMPORTNACE

1. Clean tools and machines before and after using.
2.
3. Always apply machines parts with oil.
4. Maintain level of machine oil reservoir to keep machine in good condition
5. Always use coolant when taking roughing cuts to lessen load of machine.

TEST REVIEW EXECRCISES

Select the best Answer. Write the letter of the correct answer o the blank provided before each
number.

_________ 1. The smaller diameter that is machined to a specified length on a workpiece is called
a. internal recess
b. external recess
c. filleted shoulder
d. angular shoulder

__________2. The process of machining a larger diameter of a specified length inside a hole is called
a. internal recessing
b. external recessing
c. shoulder turning
d. boring

__________3. Recesses are produced on workpiece for :
a. cutting machine parts
b. joining two parts
c. special fitting on machine parts
d. Screwing machine parts

Direction: This form should afford the Instructor to rate the Productivity/Performance of the trainee for
a give Employable Skill/Activity/Project. On the space provided for, write the points which likely
coincide with your evaluating for each of the following factors: Outstanding – (4 pts.); Plus
Satisfactions – (3 pts.); Satifactory - (2 pts.); Below Satisfactory – (1 pt.)

SATISFACTORY TASK PERFORMANCE REQUIREMENT FACTORS Rating
Provide with complete tools, MS drawing Nos. 103, 108 adn109
and materials with sizes Ø 12.7 x 150 CRS, Ø 68 x 34 and Ø A. Quality/Appearance
25.4 x 190, the trainee must: (symmetry; Verticality;
Horizontality;
1. Turn external recesses on the following parts/projects: Workmanship,
1.1 Tap wrench handle Finish)………….
1.2 Marking gauge flange B. Accuracy/Criticality
1.3 Marking gauge shaft (Exactness of
dimension/specification,
2. Working time should be within the Instructor specifications. High, Medium, Low
Tolerance and surface finish should be within the specified limits. criticality

C. Speed (50% over
estimated time . . . – (1
point) (50% time save
over estimated . . . and
(1 point).
D. Method (Economical:
use of tools ; Safety and
hygiene, Initiative)
…………….

TOTAL POINTS …………….. _____
GRADE ………………………._____

REMARKS: Working hours is approximately one (1) hour.

By:___________________________

___________________________
Designation

Operation Title: PARTING OR CUTTING –OFF
Purpose:
Parting off in the operation of turning a narrow grouse behind the workpiece to remove it from the stock
material.

Conditions or situations for the operation:
Parting or cutting-off (Figure 1, see next page), is the operation of separating a finished work

from the bar stock which the piece is machined.
In theory, the process of parting-off in the lathe is simple. The set-up of the tool is without

difficulty because it can be fed to the work carefully and one can proceed to parting-off. In practice, the
process is far from easy. Parting-off tools tends to break when too much pressure is applied especially
when vibrations between the tool and work increases. However, the difficulty can be overcome by
providing the parting tool with less rake angle, narrower at the back than at the cutting edge with
clearance around. The edge may be tapered so that it cuts deeper at the side away from the chuck.
The width of the tool should vary according to the size of the work, but should be between 3 to 8mm.

Figure 1. Parting-off In the Lathe
Before starting the operation, the speed of the machine should be reduced to about ½ that of
that for ordinary turning and feed in the tool slowly by hand. When the tool has penetrated to about the
depth equivalent to its width, it should be withdrawn and move some millimeters sideways with the
compound rest.
Parting-off is usually done on cylindrical workpiece. Some of its applications are shown in the
following illustrations.

Figure 2. Parting-Off in Stages Workpiece
Figure 3. A Parting-Off A Form Turned

Figure 4. Parting-Off A Stock With Drilled Hole

TOOLS, EQUIPMENT & MATERIALS

1. Tools

1. 1 T-wrench
1. 2 Dial Indicator
1. 3 Three-jaw universal chuck
1. 4 Four-jaw independent chuck
1. 5 Steel rule
1. 6 Vernier caliper
1. 7 Parting-off tool
1. 8 Tool holder
1. 9 Open end wrench
1.10 File

2. Materials

2.1 680 x 34 CRS
2.2 500 x 100 CRS
2.3 12.70 x 150 CRS
2.4 12.7 x 130 CRS
2.5 Cutting Oil

3. Equipment

3.1 Lathe Machine
3.2 Pedestal grinder

Procedure:
1. Prepare tools, materials and equipment
1.1 Secure all needed tools from the tool-keeper or instructor
- Replace damaged tools with good ones
1.2 Check the length of the workpiece
1.3 Check the machine to be used
- Be sure that all parts are clean and properly lubricated
2. Clamp the workpiece
2.1 Select the clamping device to be used

2.2 Mount the workpiece in the chuck, Figure 5
with minimum overhang

Figure 5. Clamping the workpiece In A Chuck
3. Select and set-up the tool

3.1 Choose the sharpest parting-off tool
3.2 Clamp the tool in the tool post at a minimum overhang, Figure 6
- The tool should be set slightly below center

Figure 6. Setting-Up Parting-Off Tool
4. Select and set-up the spindle speed

4.1 Select the speed to be used based on the material of the workpiece
4.2 Locate the nearest speed on the machine speed plate
4.3 Set the speed with lathe controls, Figure 7

Figure 7. Setting-Up Spindle Speed
5. Part-off the Workpiece

5.2 Position the tool close to the surface of the workpiece, Figure 8

Figure 8. Setting-Up The Tool To Part-Off The Workpiece
5.2 Hold a ruler or a vernier caliper to the side of the tool and move the
carriage length is aligned to the workpiece face, figure 9a & b

(a) (b)
Figure 9a & b. Laying out the Length of the Workpiece using

(a) Steel Rule (b) Vernier Caliper
5.3 Lock the saddle, Figure 10

Figure 10. Controlling The Movement Of The Carriage
5.4 Start the spindle and arrange a plentiful supply of coolant, Figure 11

Figure 11. Applying Coolant On The Workpiece
5.5 Hand feed the parting tool with an even rate of fed, Figure 12

- If the tool vibrates, increase the feeding pressure
WEAR SAFETY GOGGLES TO PROTECT EYES FROM FLYING CHIPS

Figure 12. Feeding The Parting Tool With Hand
- Before completing the parting-off withdraw the tool and deburr the slot

with a file
5.6 Part off the workpiece using left hand to feed the tool and have the right

hand ready to catch the workpiece as it is parted off, Figure 13

Figure 13. Parting-Off The Workpiece

Precautions:

IMPORTANT
1. Clean tools and machines before and after using
2. Maintain the required oil levels of machine parts
3. Keep tools in a safe place when not in use
4. Keep machines from blows and dents

Quality Criteria:

Select the best answer. Write the letter of the correct answer on the blank provided before
each number.

_______ 1. Parting off is a process of removing a finished work from the bar stock by

a. punching c. forming

b. cutting d. quenching

_______ 2. The parting-off tool can withstand pressures when cutting by grinding it

with

a. less rake angle c. wider back angle

b. greater top rake angle d. rounded edge

________3. Vibrations between the workpiece and the parting-off tool occur when

a. the tool is dull c. no clearance is provided

on the tool

b. too much pressure is d. the spindle speed is much

applied in the tool

DIRECTIONS: This form should afford the Instructor to rate the Productivity/ Performance of the

trainee for a given Employable Skill/ Activity/Project. On the space provided for, write the points which
likely coincide with your evaluation for each of the following factors: OUTSTANDING – (4 pts.); PLUS
SATISFACTORY – (3 pts.); SATISFACTORY – (2 pts.); BELOW SATISFACTORY – (1pts.);

SATISFACTORY TASK FACTORS RATING
PERFORMANCE REQUIREMENT

Provided with the drawing, A. QUALITY/APPEARANCE (Symmetry; _________

Complete tools and materials, the Vertically; Horizontality; Workmanship,

Trainee must be able to: Finish) . . . . . . _________

1. Part cylindrical work-piece B. ACCURACY/CRITICALITY (Exactness

to the specified length. Of dimension/ specification, High, Medium,

Low critically _________

C. SPEED (50% over estimated time . . . .

- (1 point) (50% time save over estimated

. . . + (1 point) . . . _________

D. METHOD (Economical; use of tools; Safety
And Hygiene, Initiative) . . . . . . . . . . _________

TOTAL POINTS (T). . . . . . . . . . . . _________
(T/4) GRADE . . . . . . . . . . . . . . _________

REMARKS: Approximate working time is
Thirty (30) minutes

__________________________________
__________________________________