Performing Bench Work (Basic)

Information Sheet 8.1.1: Offhand grinding

 Rubber Bond
Rubber bond wheel produce high finishes such as those required on ball bearing races.
Because of the strength and flexibility of this type of wheel, it is used for thin cutoff wheels.
They are also used as regulating wheels on center less grinders.

 Silicate Bond/ Water-glass Bond
This is made by melting sand, charcoal, and soda. Hard silicate wheels are used for
grinding fine edges on tools and knives. They are commonly used for large and small
wheels that are necessary to keep heat generation to a minimum. They are not
recommended for rough grinding since the bond releases abrasive grains faster than
vitrified bond wheels.

 Shellac Bond Wheels
These types of bonding material produce a very smooth and bright finishes. They are used
for grinding mil rolls, bearings, and other surfaces requiring fine finishes.

4. Grade
The grades of the grinding wheel are the degree of strength with which the bond holds the
abrasive particles in the bond setting.
The selection of the proper grade is important. Grades of wheels are ranging from A to Z (soft
to hard). Grades A thru H are soft, grade I thru P are medium, and grade Q thru Z are hard.

Wheel grade fig 8.6
The grade selected on the particular jobs depends on the following factor:

 Hardness of the material. A hard wheel is generally used on soft material and soft grades
on hard material.

 Area of contact. Soft wheels are used where the area of contact between the wheel and
the work piece is large. Small areas of contact require harder wheels.

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MEE722301 April 2010 5

Information Sheet 8.1.1: Offhand grinding

 Condition of the machine. If the machine is rigid, a softer grade of the wheel is
recommended. Light-duty machines or machines with loose spindle bearings required
harder wheels.

 The speed of the grinding wheel and the work piece. The higher the wheel speed in
relation to the work piece, the softer the wheel should be. Therefore slow wheel should
have hard grade.

 Rate of feed. Harder wheel are used for high metal removal.

5. Structure
The structure of the grinding wheel is the space relationship of the grain and bonding material
to the voids that separate them; in short it is the density of the wheel.
This is the grain graining in the wheel designated by the numbers from 1 to 12 the closer the
numbers the closer the grain spacing. If the spacing of the grain is close, the structure is
dense, if the spacing of the grain is wide the structure is open.

Wheel structure fig 8.3

In selecting wheel structure, wheel with open structures provide greater chip clearance than
those with dense structures and remove material faster than the dense wheels.

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MEE722301 April 2010 6

Information Sheet 8.1.1: Offhand grinding
Standard Marking System in grinding wheels

Sequence 1 2 3 4 5

Abrasive Type Grain Size Grade Structure Bond type

51 - A - 36 - L- 5- V - 23

ManufaPcrteufriexr’s Dense to Open Manufacturer’s
symbol indicating 19 private markings to
exact kind of 2 10 identify wheel
abrasive 3 11 (Use optional)
4 12
(Use optional) 5 13 V- Vitrified
6 14 S- Silicate
A - Aluminum oxide 7 15 R- Rubber
C - Silicon Carbide 8 16 B- Resinoid
E- Shellac
Course Medium Fine Very Fine

10 30 70 160
12 36 80 220
14 46 90 240
16 54 100 280
20 60 120 320
24 150 400

180 500

Soft Medium Hard
ABCDEFGH IJKLMNOP QRSTUVWXYZ

Example: Grade Scale

C - 80 - H - 4 - E
A - 60 - P - 14 - V
A - 24 - Q - 12 - S

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MEE722301 April 2010 7

Operation Sheet 8.2.1: Tool Grinding

Learning outcomes:
1. Cutter edges are honed and free of burrs.
2. Cutter is sharpened to conform to specifications.
3. Cutters are ground using appropriate cooling agents.
4. Cutting tool grinding is performed applying knowledge on safety procedures and using

personal protective devices.
Learning Activity:
8.1 Identify the different types of Off-hand grinders.
8.2 Describe the application of the different types of grinders.
8.3 Describe the application of the different types of grinding wheels.
8.4 Describe the procedure in grinding cutting tools.

Safety in Bench grinding
 The pedestal grinder must have a face shield.

 The face shield must be positioned so that the operator is protected from flying particles
of abrasive.

 For complete eye protection, a pair of safety glasses must be worn.

 During grinding, the cutting tool will get hot.

 To prevent the cutting tool over heating or burning the operator’s fingers, the cutting tool
is dipped into water to cool it.

 Briefly air cool high speed steel tool bits before dipping them, into the water.

 Never allow a tool to reach red heat.

 Make sure the container is filled with water before you start grinding.

 Inspect the faces of the grinding wheels.

 If the faces are uneven or the abrasive particles are not fresh and sharp, the wheel must
be dressed.

Code No. Perform Bench work (Basic) Date: Developed Date: Revised Page #
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Operation Sheet 8.2.1: Tool Grinding
Grinding of Drills
Drills are made of carbon steels and high-speed steel. Some special drills are carbide-tipped.
These are used for special jobs when the other types of drills are unsatisfactory.

Parts of a Drill Bit

fig. 8.1 fig. 8.2

 Point
The conical part of the drill. On the point, the cutting lips are ground.

 Body
The body is the part of the drill that is fluted and relived.

 Shank
The shank is the part that fits into the holding device it either straight or tapered.

 Flute
The flute is the groove of the drill. It carries out the chips and admits the coolant.

 Tang
The tang is the flattened end of the taper shank. It helps drive the drill and provides
means for driving the drill from the socket without injuring the shank.

 Dead center
Is the point at which the two lips, properly ground, meet.

 Lips
The cutting edges of the drill.

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Operation Sheet 8.2.1: Tool Grinding

Sharpening High Speed Drill Bits

Although high-speed drills have gained place in production, it is still possible to obtain the
smaller sizes made of carbon steel. Industry stopped using carbon drills because they were
too soft and did not hold up under production methods. However, school machine shops still
use the carbon drill because of its cheapness in comparison with the high-speed drill.

When sharpening or using a carbon-steel drill, extra care must be taken not to let it get hot
enough to lose the temper. If the cutting edge shows blue, it indicates the temper has been lost
in that part and the drill must be shortened that much in order to grind the soft part away. This
means not only extra work but also waste of drill. Have plenty of water ready and use care. If
necessary to grind a high speed drill dry, never dip it in water to cool it, because this is likely to
crack the lips.

Drills, like other cutting tools, have a cutting angle, a cutting edge, and various clearance
angles. These angles are explained and described in the paragraphs as follows.

Lip Clearance

In order to cut properly, the drill must have a certain lip clearance. Lip clearance is the "relief"
that is given to the cutting edges in order to allow them to enter the metal without interference.
The heel has been ground below the lip, giving the lip an opportunity to feed in. General-
purpose drills are given a lip clearance of 8º to 12º. The heel, which is on the same plane as
the lip, prevents the lip from cutting the work.

Angle of Clearance at the Center of the Drill

 The angle of clearance at the center of the drill should be greater than the angle at the
circumference of the drill. The reason for this is clear. When 0.0002 in. of stock is
removed as the drill turns one-quarter of a revolution, it is distributed around a much
larger sector on the circumference of the drill center.

 The angle of clearance at the center must be proportional to the angle outside. The
clearance on a drill is about 12º at the cutting edge. If correctly sharpened, the edge of
the angle across the web of the drill (the dead center of the drill) will be about 45º with
the line of the cutting edges. The appearance of the dead centers therefore an index to
the clearance.

 Lip clearance is very important as it takes considerable pressure to feed the drill into the
work under the best possible conditions, owing to nature of the point, and if the lips are
not properly backed off, the drill will break under feeding pressure simply because it
cannot cut.

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MEE722301 April 2010 3

Operation Sheet 8.2.1: Tool Grinding

 A drill must not be given too much clearance because excess clearance leaves
insufficient thickness of lip to carry off the generated heat. It also leaves insufficient
stock behind the cutting edge usually required for its support, thereby weakening the
cutting edge.

 A drill must have a sufficient clearance. A drill lacking enough clearance will not be able
to cut properly but will be forced into the work until it breaks. It causes the drill to
"wander", making over sized holes.

Metals Degrees

Soft and medium steels 12 to 15

Hard steels 7 to 12

Aluminum 12 to 15

Brass 12

fig. 8.3

Angle and Length of Lip

 In grinding a drill, it is important that the angle of the point to be correct, that the angles
and lengths of the lips be equal. Drills having unequal angles or unequal lengths of lips,
or both, will result in oversize holes.

 Great care must be taken to get the lips exactly
the same length and both at the same angle
with the axis of the drill.

 If the edges of the drill are ground at an angle
of 59º with the axis, the best results will be
obtained in most materials. Therefore, the drill
should be held at about 59º with the face of the
grinding wheel. For testing the angles and the
relative lengths of the cutting edges, there are
several types of gages (figure 8.4). Any
protractor will check the angles if these special
gages are not handy.

Checking lip length and angle
with a drill gauge fig. 8.4

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MEE722301 April 2010 4

Operation Sheet 8.2.1: Tool Grinding fig. 8.5

Drill Points for Different Materials

The point angles of twist drills vary for different
materials from 60 to 150º with about 118º for average
work.

 150º for hard materials
 125º for heat treated steel and drop forging
 118º for average class of work
 100º for soft cast iron
 60º for wood, hard rubber, Bakelite, and fiber.

Grinding Drills by Hand

 Hold the drill shank in the dominant hand and
support the front of the drill about 1 inch (25
mm) back from the point with the other hand
(figure 8.6).

 Holding the drill with one of its cutting edges fig. 8.6
horizontal, position it close to the face of the
grinding wheel at an angle of 59 degree
(figure 8.7).

 Grind the first cutting edge, using light pressure
on the drill while moving it slightly back and
forth on the wheel face.

 When a small amount has been ground from
the cutting edge, slowly raised the front of the
drill while pushing forward to keep the heel of
the drill in contact with the wheel. This is
necessary to grind the clearance on the cutting
edge (figure 8.8).

fig. 8.7

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Operation Sheet 8.2.1: Tool Grinding

 Grind the second cutting edge as above and
check the drill point with a drill-grinding gage.

 Regrind the drill, if necessary, to make angles,
lengths, and clearance of both cutting edges as
equal as possible.

fig. 8.8

Sharpening a Cold Chisel

 To sharpen a cold chisel, place the blade end
on the tool rest of the grinder. (figure 8.9)

 A right-handed person should steady the blade
end with the left hand. The right hand should
hold the head end of the chisel.

 Press the chisel lightly against the rotating
wheel and move it back and forth across the
wheel face.

 Keep the chisel cool by frequently dipping it in
water. Examine the chisel often to make sure
the same amount of metal is ground off both
sides and that the same angle is ground on
both sides.

fig. 8.9

Note:

When grinding such tools as chisels and punches, be careful not to burn the thin edges or
points. The tool is being burnt when it turns to purple or blue color. This causes the steel to
lose its temper, that is, it loses some of its hardness. Merely grinding off the blue color does
not bring back the hardness. Always keep the tool you are grinding cool by dipping it in water
often.

Code No. Perform Bench work (Basic) Date: Developed Date: Revised Page #
MEE722301 April 2010 6

Worksheet 8.2.1: Grinding

Learning outcomes:
1. Cutter edges are honed and free of burrs.
2. Cutter is sharpened to conform to specifications.
3. Cutters are ground using appropriate cooling agents.
4. Cutting tool grinding is performed applying knowledge on safety procedures and using

personal protective devices.

Learning Activity:
8.1 Identify the different types of Off-hand grinders.
8.2 Describe the application of the different types of grinders.
8.3 Describe the application of the different types of grinding wheels.
8.4 Describe the procedure in grinding cutting tools.

Write your answer on the space provided.

1. __________________The process whereby the piece of metal is being shape by bringing it
contact with a rotating abrasive wheel

2. __________________A type of grinding where by a piece of metal must be removed or
grind with a great accuracy.

3. __________________The other term for non-precision grinding.

4. __________________This has the function of holding the abrasive grains together in the
form of a wheel.

5. __________________The bond that produces wheels with large pores make it to cut
easily. These bonds are suited to wheels use for rapid removal of metal.

6. __________________These types of bonding material produce a very smooth and bright
finish.

7. __________________The degree of strength with which the bond holds the abrasive
particles in the bond setting.

8. __________________This are grinders used in non-precision grinding.

9. __________________A type of abrasive grains that are suited for grinding materials that
have a low tensile strength (aluminum, brass and bronze) and high density, such as
cemented carbides, stones, and ceramics.

10. __________________ Placed on the grinding wheel to protect the operator from coming in
contact with the rotating wheel.

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
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April 2010 1

Worksheet 9.2.1: Determine Job Requirements

Learning outcomes:

1. Components, assemblies or objects recognized as required.
2. Dimensions identified as appropriate.
3. Instructions identified and followed as required.
4. Material requirements identified as required.
5. Symbols recognized as appropriate in the drawing.
6. Tolerance, limits and fits identified in the drawing

Learning Activity:

9.1 Identify components, assemblies or objects required.
9.2 Identify dimensions
9.3 Identify the materials needed
9.4 Identify symbols
9.5 Identify limits and fits.
9.6 Identify instructions

BLUEPRINT READING – EXERCISE 1

Refer to the drawing “TOP PLATE” for questions 1 to 18, answer the following.

1 What is the name of the part?
2 What is the blueprint number?

3 Of what material is it made?

4 How thick is it?

5 What is the overall width (B)?

6 What is the overall length (A)?

7 What radius forms the front of the plate?

8 How many drilled holes are there?

9 What is the center distance of the two drilled holes?

10 What radius is used to form the back rounds of the piece?

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
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Worksheet 9.2.1: Determine Job Requirements

11 What is the clearance (C) between the body and the back
of the plate?

12 What size of drill is used in the drilled holes?

13 What is the reamed size of the holes?

14 How much material is there between the reamed hole
and the outside of the piece formed by the radius?

15 What is the radius of the fillet used along the back of the
piece?

16 What type of line is drawn through the center of a drilled
hole?

17 What is the scale of the drawing?

18 Give the order number for the product.

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
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Worksheet 9.2.1: Determine Job Requirements

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
ALT723307
April 2010 3

Worksheet 9.2.1: Determine Job Requirements

Learning outcomes:

1. Components, assemblies or objects recognized as required.
2. Dimensions identified as appropriate.
3. Instructions identified and followed as required.
4. Material requirements identified as required.
5. Symbols recognized as appropriate in the drawing.
6. Tolerance, limits and fits identified in the drawing

Learning Activity:

9.1 Identify components, assemblies or objects required.
9.2 Identify dimensions
9.3 Identify the materials needed
9.4 Identify symbols
9.5 Identify limits and fits.
9.6 Identify instructions

BLUEPRINT READING – EXERCISE 2

Refer to the drawing “CARRIER SUPPORT” for questions 1 to 18, answer the following.

1 What is the name of the part?

2 What is the blue print number?

3 Of what material is it made?

4 How many Cam Carrier Support are required?

5 What is the largest diameter?

6 What is the overall length?

7 How thick is the flange?

8 How many holes are drilled through the flange?

9 How many degrees apart are they spaced?

9 What is the diameter of the circle on which the countersunk
holes are located?

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
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Worksheet 9.2.1: Determine Job Requirements

11 For what size screw must they be drilled?
12 What operation is performed to allow the head of the screws

to rest flush with the flange?
14 What tolerance is permitted on linear dimensions?
15 What is the largest size to which the hole through the center

can be bored?
16 What is the smallest size to which the hole through the center

can be bored?
17 What is the diameter of the recess on the right end of the piece?
18 What is the depth of the recess?
19 What is the size and angle of chamfer?

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
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April 2010 2

Worksheet 9.2.1: Determine Job Requirements

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
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April 2010 3

Information Sheet 10.1.1: Prepare Work Area and Safety

Learning outcomes:
1. Work area is prepared according to workplace requirements

Learning Activity:
10.1 Identifying needed tools and equipment.
10.2 Describe shop safety practices.

Preparing work area

One of the very first items on your list of things to do in any project understands what the job
requirements are. The clearer you are about what is required from the start, the less chance
there will be of problems occurring later on. Knowing the different types of operation to be
done to the work will enable you to select and prepare the necessary tools and equipment
needed. Clean, orderly and comfortable working area is very important. It is good for health,
away from danger, efficiency, gain, save times, reduce wastes, etc. To do this knowledge on
housekeeping and safety is essential

HOUSEKEEPING

Housekeeping is the term used in industry to mean the safe storage of tools, parts, and all the
rest of the items used in manufacturing.

Proper housekeeping in a machine shop means paying particular attention to five specific
areas:

Floors fig. 10.1
Floors must be kept clean and free of debris at all fig. 10.2
times. Stray pieces of stock or piles of chips or
shavings can be someone to trip or fall. Oil, greases
or coolant spills are extremely hazards and must be
cleaned up immediately.

Most spills and leaks are the result of improper
operation, set-up or maintenance of the machine.
When a spill of any kind occurs, you should attempt to
determine the cause and correct it.

Never leave dirt or debris in piles on the floor after
sweeping. Pick it up and put it in the proper disposal
container.

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
MEE722301 April 2010 1

Information Sheet 10.1.1: Prepare Work Area and Safety fig. 10.3

Work surfaces

Work surface should be kept clear and clean at all
times. Before you begin a job, make sure the work
surface is clean of any tooling you are not using.
Clean up any chips or debris so they do not interface
with your wok. When you finish, clear away your
tooling and clean up the area so the machine is ready
to be used again.

Care and storage of tools

Cutting tools, drills bits, chuck keys, and other tools
and equipment should be stored in their proper place
when not in use. Tools that are not properly stored
can become damaged if they fall. They can also
cause serious damage to the machine in they come
into contact with moving parts.

Dirty, dull or damage cutting tool and drill bits can
break apart during use, causing serious injury. Make it
a point to inspect each tool or bits before you use it,
and make sure you know what a good tool looks like.
Tools that are in unsatisfactory condition should be
removed from service until they can be sharpened,
repaired or replaced.

Cleaning rods and brushes should be stored in their
proper place. Rods left leaning against a machine can
fall to the floor and create a trip hazard. Brushes left
lying on machines can obstruct your view, interfere
with the machine’s operation or come into contact
with moving parts and cause damage.

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
MEE722301 April 2010 2

Information Sheet 10.1.1: Prepare Work Area and Safety

Store of stock and supplies

Stocks of supplies, raw materials and finished
materials should be clearly marked and neatly stored.
Round stock should be stored in boxes or stacked
between supports. Materials should not be stored in
walkways or traffic aisles and should never be
allowed to block an exit or entrance, even temporarily.

Clearly marked work areas fig. 10.4

Each machine should have its on clearly marked
workspace. Machining operation should be confirmed
to those workspaces. If a work piece extends beyond
a machine’s designated area, warning signs, flags or
other markers should be posted to warn others of a
potential hazard.

Wear Protective Clothing and Safety Equipment

Wear close fitting clothing appropriate for the job
shirts or jumper with sleeve cut-off or rolled above the
elbows. When wearing work aprons. Always tie the
string on your work apron in the back and keep the
strings as short as possible. Loose string dangling
from the front an apron is likely be caught in a
machine

Hairnets are required in many machine shops for both
men and women. Like shirt sleeves and apron strings,
loose hair can be caught in rotating or moving
machine parts.

fig. 10.5

Personal Protective Equipment (PPE)

These are the basic safety requirement whenever you work around in any types of machine
shop. Always make sure you have all of the Personal protective equipment required

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
MEE722301 April 2010 3

Information Sheet 10.1.1: Prepare Work Area and Safety fig. 10.6
fig. 10.7
Safety glasses or goggles fig. 10.8

Eye protection is essentials for everyone in the
machine shop workers and visitors alike. Metal
fillings, chips and shavings, pieces of broken tools
and other machine parts don’t just fly toward the
operator. Safety glasses with side shields should be
worn at all times when you are in the machine shop
(figure 10.6).

Face Shield

When using power tools for hand grinding, disc
grinding or even welding, cutting etc, to protect not
only the eye but even your face a face shield should
be worn (figure 10.7). Use face shields in combination
with goggles or safety glasses when you must protect
yourself from impact hazards, even in the absence of
dust or potential sparks and splashes.

Hearing Protection

Prolonged exposure to loud noise can cause
impairment or lost of hearing. Wear a suitable
protective device such as earplug or earmuffs when
working around particularly noisy types of machinery
or performing operations that are special loud. Make
sure you know when and where you need to wear
hearing protection.

Earmuffs fig. 10.9

These are normally hard plastic cups, with sound fig. 10.10
absorbent filling, that fit over the ears and are sealed
to the head by cushion seals (figure 10.10). They
need to be pressed to the head either by a headband
or by special fittings attached to a safety helmet. To
avoid any interference with other forms of PPE, it is
important to note that most headbands can be worn
over the head or the chin or around the back of the
neck according to the manufacturer's instructions.

Disposable ear plugs are made of soft, noise-
absorbing foam.

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MEE722301 April 2010 4

Information Sheet 10.1.1: Prepare Work Area and Safety fig. 10.11
fig. 10.12
Earplugs
These fit inside the ear canal and can be reusable or fig. 10.13
disposable according to the manufacturer's
instructions (figure 10.9). They may sometimes be
attached to a cord to prevent being lost. Ear plugs
may not be suitable for people with a history of ear
problems.

Gloves

Most machining should be done with bear hands.
However cut resistant gloves should be worn
whenever changing saw blades, or when handling
rough stock where sharp edges or burrs are hazard.
Gloves should also be used when handling hot work
pieces from lathes, mills or drills.

REMEMBER:
Do not wear gloves when performing machining
operations. They are easily caught on rotating tools,
work pieces, or on moving machine parts.

Safety Shoes
Wear thick soles shoes if heavy work is being done
steel-toed shoes provide protection from failing
objects like tools, work pieces or raw stock sturdy,
thick slip-proof soles can help you falls on slick sports
and from sharp objects left on the floor.

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Information Sheet 10.1.1: Prepare Work Area and Safety
General Safety Precautions

 Do not operate any machine shop equipments unless you have properly trained in its use
and are familiar with the operation to be performed.

 The shop is a place of serious work so work and don’t play.

 Read and become familiar with the operator’s manual for the machine you are using.

 Dressed properly; never use long sleeve shirts when working with machines. Remove
watches, bracelets, rings, and necklaces before working with machines. Keep your haircut
short. Wear eye protection at all times.

 Do not attempt to lift heavy tooling or work piece without the help of another person or a
mechanical aid.

 Keep all hand tools; files, screw drivers, scribers, etc., on the table and in cabinets. NEVER
in your pockets. They may hurt you or hurt others.

 Use only tools that are in good condition. A file or a hammer with a cracked handle is
dangerous. Mushroom heads of cold chisels should be ground regularly. Keep your tools in
good conditions.

 Make sure you know what guards are required for the operation you are performing. Do not
begin any operation until all required guards are in place. During the operation, never reach
around or over any guard until the machine has come to a complete stop.
 Do not start a machine tool with the blade, bit or cutter in contact with the work piece.

 Keep your hands dry before touching any power tool and be sure that you are not standing
on a wet spot.

 Always use a tool or brush to remove accumulated chips. Never touch chips with your bare
hands.

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MEE722301 April 2010 6

Information Sheet 10.1.1: Prepare Work Area and Safety
 Avoid distractions. Do not operate machine tools if you are angry or upset. Keep your mind
on your job while the operation id underway.

 Wait until the machine has come to a complete stop before making adjustments, taking
measurements or removing work pieces.
 Be careful when handling cutting tools or work pieces after the operation is complete. They
may be hot and sharp.

 Keep your work area clean and orderly. Remove other things, which have nothing to do with
your current work. Oil spills on floor should be cleaned immediately.

 Return all tooling to its proper storage place after use.

 Keep flammable materials; paint, gasoline, thinner, away from flame and sparks.

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
MEE722301 April 2010 7

Worksheet 10.2.1: Grinding

Learning outcomes:
1. Work area is prepared according to workplace requirements
Learning Activity:
10.1 Identifying needed tools and equipment.
10.2 Describe shop safety practices.

True or False
Write O if the sentence is true and X if false. Write your answer on the space provided.

1. ______ Housekeeping is the term used in industry to mean the safe storage of tools, parts,
and all the rest of the items used in manufacturing.

2. ______Always wait until the machine has come to a complete stop before making
adjustments, taking measurements or removing work pieces.

3. ______ When drilling start the machine even, when the drill bit is in contact with the work
piece.

4. ______ Wear gloves when performing machining operations such as drilling and grinding.

5. ______ Prolonged exposure to loud noise can cause impairment or lost of hearing.

6. ______ Use face shields in combination with goggles or safety glasses when you must
protect yourself from impact hazards, even in the absence of dust or potential sparks and
splashes.

7. ______When wearing work aprons. Always tie the string on your work apron in the back
and keep the strings as short as possible.

8. ______The first thing you must learn before working in the machine shop is safety.

9. ______ Hairnets are required in many machine shops for both men and women.

10. ______ Always use a tool or brush to remove accumulated chips. Never touch chips with
your bare hands.

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
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April 2010 1

Information Sheet 11.1.1: Check and Measure Work piece

Learning outcomes:

1. Measuring tools are selected and used according to the level of accuracy required.
2. Measurements taken are accurate to the finest graduation of the selected measuring

instrument.
3. Measuring technique used is correct and appropriate to the device used.

Learning Activity:

11.1 Identify the function of the different types of measuring tools.
11.2 Select proper measuring tool.
11.3 Identify and read measurement from selected measuring tool.

Measuring Lengths Steel rule fig. 11.1
Steel rule fig. 11.2
With a reasonable amount of care, fairly accurate
measurements can be made using steel rules.
Whenever possible, put the end of a rule against a
shoulder or step to ensure an accurate measurement.

Through constant use, the end of the steel rule
becomes worn. Measurements taken from the end,
therefore, are often inaccurate. Fairly accurate
measurements of flat work can be made by placing
the 1-in. or 1-cm graduation line on the edge of the
work, taking the measurement, and subtracting 1 in.
or 1 cm from the reading. When measuring flat work,
be sure that the edge of the work. If the rule is placed
at an angle to the edge the measurement will not be
accurate. When measuring the diameter of round
stock, start from the 1-in. or 1-cm graduation line.

The Rule as a Straightedge

The edges of a steel rule are ground flat. The rule Rule as a straight edge
may therefore be used as a straightedge to test the fig. 11.3
flatness of workpieces.

The edge of a rule should be placed on the work
surface, which is then held up to the light. In-accurate
as small as a few thousandths of an inch or 0.05-mm
can easily be seen by this method.

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
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Information Sheet 11.1.1: Check and Measure Work piece
The Vernier Caliper

The Vernier Caliper is the most common tool in the machine shop because of its accuracy,
where it can measure inside and outside measurements up to .02 mm or less.

Parts of a Vernier Caliper fig. 11.4

The Least Count

Vernier calipers are available with different accuracy’s this accuracy’s is what we call ‘least
count’. The selection of the vernier caliper depends on the accuracy needed and the size of
the job to be measured.

Now that you know the parts of a vernier caliper, let’s proceed on reading vernier
measurements, you must be familiar with the main scale and the vernier scale of your caliper,
but first we must know what is the least count of the vernier caliper you are going to use!

The least count is determined by the graduations of the main scale and the vernier scale
divisions.

They are the divisions found in the vernier scale of your caliper.
Example of least count: 0.01, 0.02, 0.05 mm

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Information Sheet 11.1.1: Check and Measure Work piece
Determining The Least Count Of Vernier Calipers

Look at the vernier below; to get the least count we must divide the number of division on the
vernier scale to the one division of the main scale.

Main Scale

Vernier Scale
fig. 11.5
Now look on the vernier above, one main scale division is 1mm, then look on the vernier scale,
how many divisions are there. Now lets divide 1mm main scale division to the number of
division in the vernier scale.

1 main scale division = 1 mm
Number of vernier divisions = 50 division
1mm/ 50mm = 0.02 mm

Therefore, the least count is 0.02 mm, 1 division of the vernier scale is 0.02 mm

Reading Vernier Caliper Measurements

1. First! Read the main scale to the left of the zero of the vernier in millimeters.
Main Scale Reading (MSR): 13 mm

The 0 mark pass over the 13th fig. 11.6
division of the main scale

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
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Information Sheet 11.1.1: Check and Measure Work piece
2. Now look at the vernier scale.
fig. 11.6

Vernier Scale
3. Note, which one of the vernier divisions is opposite the line on the main scale.

fig. 11.7

Vernier Scale Reading = 0.42 mm

4. Then, Add the main scale reading to the vernier reading.

VSR : 41st Div = 0.42 mm

MSR : 13 mm

fig. 11.8 MSR: 13.00 mm
Vernier Scale +
VSR: 0.42 mm

Final Reading
= 13.42 mm

Main Scale

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
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Information Sheet 11.1.1: Check and Measure Work piece
Micrometer Caliper

Micrometer Caliper is a measuring instrument that enables accurate measurement to be
taken. It is probably the most commonly used precision measuring device in industry. They are
available in various size and frames.

Parts of a Micrometer fig. 11.9 fig. 11.10

Micrometer Caliper measurements

Measurements are made between the anvil and the
spindle. The spindle is fitted to the thimble both move
along a fine screw, a ratchet control is fitted to the
micrometer to ensure that the measuring force remain
the same under all circumstances.

The lock nut can be used to fix the spindle in a certain
position.

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Information Sheet 11.1.1: Check and Measure Work piece
Here’s how to read measurements from a micrometer caliper!
1. First read on the barrel scale or sleeve the number of millimeters that are completely

visible.

fig. 11.12

Sleeve Reading = 28 mm
2. Then add any half millimeters that are completely visible.

fig. 11.13

Sleeve reading = 28 mm + 0.5 mm minor division = 28.5
3. Note the number of the graduation on the thimble scale that is level with the datum line.

fig. 11.14

Thimble Reading = 0.32 mm
4. And finally, add the thimble reading to the other reading.

Sleeve Reading = 28.5 mm
+
Thimble Reading = 0.32 mm
Final Reading = 28.87 mm

Code No. Perform Bench Work (Basic) Date: Developed Date: Revised Page #
MEE722301 April 2010 6

Worksheet 11.2.1: Check and Measure Work piece

Learning outcomes:

1 Measuring tools are selected and used according to the level of accuracy required.
2 Measurements taken are accurate to the finest graduation of the selected measuring instrument.
3 Measuring technique used is correct and appropriate to the device used.

Learning Activity:

11.2.1 Identify the function of the different types of measuring tools.
11.2.2 Select proper measuring tool.
11.2.3 Identify and read measurement from selected measuring tool.

Measuring Activity
Write on the space provided the measurement of the following parts of the given work piece.

A. ____________mm
B. ____________mm
C. ____________mm
D. ____________mm
E. ____________mm
F. ____________mm
G. ____________mm
H. ____________mm
I. ____________mm
J. ____________mm

Code No. Bench Work (Basic) Date: Developed Date: Revised Page #
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