metrology lab mannual 15 5-14

Prepared by SUDARSHAN BOLLAPU., M.TECH (Ph.D.) DEPARTMENT OF MECHANICAL ENGINEERING, CUTM 1

CENTURION UNIVERSITY OF TECHNOLOGY &

MANAGEMENT

SCHOOL OF ENGINEERING & TECHNOLOGY,

Paralakhemundi

Department of Mechanical Engineering

METROLOGY LAB LABORATORY MANUAL

Name: …………………………………………………..

Reg. No: …………………………………………………

Branch: ………………………………………………….

Year & Semester: ………………………………………


METROLOGY LAB EXPERIMENTS

1. Measurement of lengths, heights, diameters by Vernier Calipers, Micrometers etc.

2. Measurement of bores by internal micrometers and dial bore indicators.

3. Linear measurement using dial gauge, slip gauge, and calibration of dial gauge

4. Use of gear teeth, Vernier Calipers and checking the chordal addendum and chordal height

of spur gear.

5. Angle and Taper measurements by Bevel protractor, Sine bars, etc.

6. Machine tool “alignment test on the Lathe.

7. Machine tool alignment test on milling machine.

8. Tool maker’s microscope and its application.

9. Use of spirit level in finding the flatness of surface plate.

10. Thread measurement by two wire/three wire method or Tool makers’ microscope.

11. Surface roughness measurement by Taly Surf.

12 .To calibrate the profile projector using given samples which dimensions is measured by

micrometre as standard

13. Surface Wear Resistance Test using Electro Spark Coating Device.

CNC:

1. Machining of simple components on CNC lathe

2. Machining of simple components on CNC Milling

3. Inspection of quality and dimensional practice using Coordinate Measuring Machine


Cycle-1-Experiments

Cycle-1-Experiments

SNO. NAME OF THE EXPERIMENT

1 Measurement of lengths, heights, diameters by Vernier Calipers, Micrometers

2 Measurement of bores by internal micrometers and dial bore indicators.

3 Linear measurement using dial gauge, slip gauge, and calibration of dial gauge

4 Use of gear teeth, Vernier Calipers and checking the chordal addendum and chordal

height of spur gear.

5 Angle and Taper measurements by Bevel protractor, Sine bars

6 Machine tool “alignment test on the Lathe.

Cycle -2 experiments

Cycle-2-Experiments

SNO. NAME OF THE EXPERIMENT

1 Machine tool alignment test on milling machine.

2 Tool maker’s microscope and its application

3 Use of spirit level in finding the flatness of surface plate

4 Thread measurement by two wire/three wire method or Tool makers’ microscope

5 Surface roughness measurement by Taly Surf

6 To calibrate the profile projector using given samples which dimensions is measured

by micrometre as standard


Experiment No. 1 Date: / / 20

MEASUREMENT OF LENGTHS, HEIGHTS, DIAMETERS BY

VERNIER CALIPERS, MICROMETERS

Aim:

To measure the diameters of the given work piece at various sections using Vernier Calipers.

Equipment Required:

1. Vernier Calipers with Least Count = 1mm/50 OR 0.02mm

2. Work piece of various cross sections with different diameters.

Construction:-

Vernier consists of 2 scales one fixed and other movable. The fixed scale known as the main

scale is calibrated on “L” shaped frame and carriers a fixed jaw. The movable vernier scale

slides over the main scale and carriers a measuring tip when the jaws are closed the zero of

vernier and main scale coincide. An adjustment is provided to lock the sliding scale.

Principle:

Vernier Calipers is the most commonly used instrument for measuring outer and inner

diameters. It works on the principle of Vernier Scale which is some fixed units of length (Ex:

49mm)divided into 1 less or 1 more parts of the unit(Ex: 49mm are divided into 50 parts).The

exact measurement with up to 0.02mm accuracy can be determined by the coinciding line

between Main Scale and Vernier Scale.

Total Reading = M.S.R + L.C X V.C

Where:

M.S.R – Main Scale Reading

L.C – Least Count

V.C – Vernier Coincidence

Use:-

These are used for both – internal and external measurement, its generate used for measuring

by closing the jaws on work surface and taking readings from main scale is examined to certain

which of its division coincide and added to the main scale reading.

Following are the constructional parts of vernier caliper:

(1) Fixed scale and movable scale: The Vernier Caliper consists of two scales: one is fixed and

the other is movable.

(2) Fixed and movable jaw: The fixed scale is called as main scale which is calibrated on L-

shaped frame and carries a fixed jaw. The movable scale, called vernier scale slides over the

main scale and carries a movable jaw. The movable jaw as well as the fixed jaw carries


measuring tip. When the two jaws are closed the zero of Vernier scale coincides with the zero

of main scale. For precise setting of the movable jaw an adjusting screw is provided.

(3) Lock nut: An arrangement is provided to lock the sliding scale on the fixed main scale.

(4) Graduated beam: Main scale markings are there on graduated beam.

(5) Blade or Depth probe: Measures depth.

Least count: The smallest value that can be measured by the instrument is known as its least

count.

Least count of Vernier Caliper:

There are two methods to find the least count of Vernier caliper

(a) First Method (Principle of Vernier)

Length of 49 divisions on main scale = Length of 50 divisions on Vernier scale

It means it follows that for the same length if there is n division on main scale then there should

be n+1 division on

Vernier Scale for the same distance.

• Value of smallest division on main scale = 1 mm and

• Value of smallest division on Vernier scale = 49/50 = 0.98 mm

Least count = Value of smallest division on main scale –

value on smallest division on Vernier scale

= 1 – 0.98

= 0.02 mm

(b) Second Method

Least Count = Value of smallest division on Main Scale

Total no. of divisions on Vernier Scale

Smallest division on Main scale = 1 mm Total no. of divisions on Vernier Scale = 50 markings

So for this type of Vernier Caliper L.C. = 1/50 = 0.01mm

Least count= One division of main scale reading/ No. division on scale .mm

49 MSD=50 VSD

1 MSD=1mm

1 VSD= 49 MSD/50 VSD

L.C= 1MSD- 1VSD


= 1- 49/50

=0.02 mm

Reading a vernier caliper:

Formulae for calculating total reading with the help of Vernier caliper is –

Total reading=MSR + (VSR X LC) mm

Here 12.84mm is the total reading. If 12.84mm is the total reading then the main scale reading

is 12. We know that the usual least count of V.C. is 0.02 mm.

12.84 =12+ (0.02Xvernier division coinciding with main scale division)

12.84-12 =0.02Xvernier division coinciding with main scale division

0.84 =0.02Xvernier division coinciding with main scale division

42nd division of vernier scale exactly coincides with main scale division

12.84=12+ (0.02X42) =12.84mm


Procedure:

1. The Least Count is to be determined.

L.C = (Minimum Main Scale Reading) / (No. of Vernier Scale Divisions)

2. The work piece is placed between the jaws of Vernier Calipers correctly.

3. The reading on Main scale which is just behind the first Vernier Scale Division is noted as

Main Scale Reading.

4. The Division on Vernier Scale which coincides with the line on Main Scale is noted down

as Vernier Coincidence.

5. The Diameter can be calculated using the given Formula.

Precautions:

1. Make sure the Vernier Calipers are clean.

2. Clean the measuring faces with paper or cloth.

3. Make sure the work piece axis is perpendicular to the Vernier Calipers.

Calculations:

Length of the specimen:

S No

Main Scale

Reading

VSR VSR X LC TR= MSR + (VSR

X LC) mm

1

2

3

4

5

Diameter of the specimen:

S No

Main Scale

Reading


X LC) mm

1

2

3

4

5


Thickness of the specimen:

S No

Main Scale

Reading


X LC) mm

1

2

3

4

5

Result:

The experiment is conducted on the vernier callipers for measuring for the physical quantities

of the given specimen.

1. Length of the specimen - --------------------------- mm

2. Diameter of specimen- ------------------------------ mm

3. Inner diameter of the hollow cylinder- ----------- mm

4. Outer diameter of the specimen- - ---------- ------mm

5. Thickness of the specimen- ------------------------ mm

B) MICROMETER:


Procedure:

1. The micrometers is checked for zero error.

2. The given component is held between the faces of the anvil and spindle.

3. The spindle is moved by rotating the thimble until the anvil and spindle touches the

cylindrical surface of the component.

4. Fine adjustment is made by ratchet .the main scale reading and thimble scale reading are

noted.

5. Two are more reading are taken at different places of the component.

6. The readings are tabulated and calculated.

TABULATION:

Sl. No Main scale

reading(MSR)

mm

Vernier scale

Division

(VSD)

Vernier scale

reading(VSR) =VSD X

Least count in mm

Total reading

(M.S.R+V.S.R)

In mm

RESULT:

• The diameter of the given cylindrical component is determined to an accuracy of 0.01mm.

• The result is checked with digital micrometre.

• The diameter of the given cylindrical component is____________mm.

Viva questions:

(1) Define (a) Metrology (b) Least count (c) Engineering Metrology (d) Measurand.

(2) What is the scope of metrology in industries?

(3) State different precision linear measuring instruments.

(4) Which linear measurements can be measured by linear measuring instruments?

(5) What is the "Vernier principle"? Explain it with suitable example.

(6) Draw neat sketch of vernier caliper.

(7) List out constructional parts of vernier caliper.

(8) Is it possible to set the dimension 15.73 mm on Vernier Caliper having of least count

0.02mm? Why?


(9) Is it possible to set the dimension of 15.72 mm on vernier caliper having least count of

0.02mm? Why? If yes then show the dimension of 15.72mm on vernier caliper of least count

0.02mm.

(10) Show the following readings on vernier caliper of least count of 0.02mm least count: (a)

6. 84mm (b) 10.28mm.

(11) Differentiate between “A” type, “B” type and “C” type of vernier calipers.

(12) List out two applications of vernier caliper.

(13) State whether the following statements are true or false. Correct the false statements:

(a) Vernier Caliper has a provision of ratchet for ensuring correct measuring pressure.

(b) Step height can be measured by vernier caliper.

(c) “B” type of vernier caliper is used for marking purpose.

(d) Vernier Caliper obey’s Abbe’s Principle of Alignment.

(e) Vernier Caliper is an example of Line standard.



MEASUREMENT OF BORES BY INTERNAL MICROMETERS AND

DIAL BORE INDICATORS.

Aim:-

To determine inside diameter and bore diameter is a given hollow specimen

Apparatus:-

Inside micro meter, hollow specimen

Micro meter:-

It is one of the most common and most popular form of measuring instrument for precious

measurement with 0.001mm accuracy are also available.

Principle:-

Micro meter works on the principle of screw and nut. When screw is turned through nut one

revolutions it advances by one pitch distance i.e., one revolution of screw corresponds to a

linear moment of a distance equal to the pitch of the thread

L.C= Pitch of the spindle/ No of divisions on the spindle

Procedure:-

1. Select the micro meter with a desired range depending upon the size of the work piece to be

measured.

2. The next step is to check it for zero error. In case of 0.25mm micrometre, the zero error is

checked by contracting the faces of fixed anvil and the spindle.

3. The barrel has graduation, in travels of 1mm above the reference line

4. For measuring the dimension, hold work b/w faces of the anvil the spindle by rotating then

touches the work piece

5. Take the thimble reading with coincides with the reference line on the sleeve.

Total reading = MSR + (PSR X LC) mm


1. CD Left jaw (2) Right jaw (3) Contact point (4) Clamping knob (5) Sleeve (6) Thimble

(7) Ratchet stop

Sleeve 22.5mm

Thimble 37mm

Reading 22.87mm

Precautions:-

1. First clean the micro meter by wiping off dirt, fit, dust grit off it.

2. Clean them with a piece of cloth or paper

3. Set zero readings on instrument before measuring.


Inner diameter of the spicemen-1

S No

Main Scale

Reading

(mm)

VSR

(mm)

VSR X LC TR= MSR + (VSR

X LC) mm

1

2

3

4

5

Inner diameter of the spicemen-2

S No

Main Scale

Reading(mm)

VSR(mm) VSR X LC TR= MSR + (VSR

X LC) mm

1

2

3

4

5

Theory:-

Bore gauge, is generally used to determine the bore diameter of components. Bore gauge

consists of following parts.

1. Dial gauge

2. Vertical column

3. Arrangement of anvil and washer

4. Movable spindle

B) DIAL BORE INDICATIORTHEORY AND DESCRIPTION:

Dial bore indicator consists of measuring head and guide is attached with extension rod

&collars for specific dimension chosen from the table in the instrument box, holder is

assembled to the measuring head and dial indicator is fixed inside the holder during tightening.

The condition is initially 1 kgf is applied to the dial indicator for getting exact reading.

PRINCIPLE: Dial bore indicator is works on comparator principle.


PROCEDURE:

1) Once approximate bore is finding out by using inside micro meter.

2) Chose the same little more size extension rod & collar if necessary select and fit.

3) Keep the dial bore indicator into the specimen bore.

4) Repeat same procedure to get the bore diameter at different positions of specimen

Least count = 0.01mm

Sample calculations:-

Least count (LC) =0.01mm

Anvil size = 45mm

Washer size = 45mm


Total indicator Reading = 14 X 0.01= 0.145mm

Total Reading= (Anvil size + Washer size)-(Dial indicator for Reading)

= (45+4.5)-(0.145) =49.355mm

Calculation Total reading:-

Bore diameter = (Anvil size + Washer Size) - (Dial indicator Reading).

Inner Diameter of the specimen-1:

S No

Anvil

Size

Washer size Dial indicator

reading

TR= Anvil size+

Washer size – Dial indicator

reading(mm)

1

2

3

4

5

Inner Diameter of the specimen-2:

S No

Anvil

Size

Washer

size

Dial indicator

reading

TR= Anvil size+

Washer size – Dial indicator

reading(mm)

1

2

3

4

5

Result:-

The experiment is used to find the inner diameter/bore diameter of the hollow specimen of

given specimen

The inner diameter of the hallow specimen is ---------------- mm

The bore diameter of the given specimen is ……………….mm



LINEAR MEASUREMENT USING DIAL GAUGE, SLIP GAUGE, AND

CALIBRATION OF DIALGAUGE

Aim: - Linear Measurement Using Dial Gauge, Slip and Calibration of Dial Gauge.

Apparatus: - Dial Gauge, Slip Gauge, Dial Gauge Indicator

Theory:-

The different component of dial gauge indicator is shown in fig. It consist of plunger,

removable contact pt., stem a transparent glass cover, calibrated dial pointer, bezel camp or

bezel locking nut. Revolution counter in order to counter in order to count the no of revolution

of a pointer, dust proof cap etc.

It consists of a plunger which slides in bearing and carries a rack with it. The rack is meshed

with pinion (P1) again pinion (P2) and gear (G2) are on same spindle [because of which

magnification is taking place]. The gear (G1) is meshed with (P1) again pinion (P2) and gear

(G2) are on spindle basically gear (G2) is meshed with pinion (P3) on whose spindle pointer is

attached. The pinion (P3) is meshed with gear (G3) on which a light is here spring is attached

in order to guide the movement of plunger rack guide is provided and to bring the plunger to

its initial position a light coil spring is attached to plunger.

Any linear displacement given causes rack to move upward during this upward movement as

rack is meshed with pinion (P1) and gear (G1) rotate by some amount but as the no of teeth on

gear (G1) is more compared to that of pinion (P2) which is meshed with it rotate more time.

Let us say if there is 100 teeth on gear G1 and 10teeth on pinion P2 the 1st stage of

magnification is 100/10=10 times again.

Therefore overall magnification can be calculated,

(G1 X G2)/ (P2 X P3)

EG: (100x100/10x10) = 100

In this way dial indicator works you can take diff readings by keeping standard and object.

Then comparison can be made.

The magnification is about 250-1000.

Dial gauge -

Dial gauges divided in two categories, type1 &type2for general engineering purpose depending

upon the movement of the plunger. These are manufactured in two grades, grade a and grade

b, with total plunger movement or lift of 3,5 and 10mm. Type1 dial gauge has the plunger

movement parallel tip the plane of dial and type 2 has the plunger movement perpendicular to

the plane of dial.


Indicator gauge-

Dial indicator has been used with several auxiliary devices for a wide variety of length

measurement. Obviously dial indicator can be used for carrying the needed complimentary

function, resulting in a single tool, it is known as indicator gauge. It must be remembered that

indicator gauge are always comparator type measuring instrument and require the use of a

setting gauges for establishing the basic measuring position

Slip gauge:

Slip gauges with three basic forms are commonly found. These are rectangular square with

center hole, and square without center hole. Rectangular forms is the more widely used because

rectangular block are less expensive to manufacture, and adopt themselves better to application

where space is restricted or excess weight is to be provided. For certain application squarely

gauges, through expensive, are preferred. Due to their large surface area, they wear longer and

adhere better to each other when touch to high stack.


PROCEDURE FOR SLIP GAUGES:

1. The slip gauges are cleaned by using cloth

2. The thickness of the given MS plate is determined to the nearest 0.1mm size by using micro

meter.

3. The slip gauges are selected to built up required dimension.

4. Required combination of slip gauges is built up by wringing.

5. The built up gauges is wrung with the wringing faces of the measuring jaws.

6. The jaws and the built up gauges are held in the holder.

7. The given MS plate is placed between the flat surfaces of the measuring jaws and the

thickness of the plate is measured.

OBSERVATION:

Slip gauge

For linear measurement least count = (0.2/200)=0.001 mm/div

For standard dimension

For specimen

Main scale reading =MSR = -------


Circular scale reading =CSR= ---------

Total reading (TR) = MSR + (CSR * LC)

Total Height of specimen = -----------

RESULT:

• The thickness of the given MS plate is measured by using slip gauges.

• The thickness of the given MS plate is _______________ mm.

PROCEDURE FOR DIAL GUAGE:

1. The slip gauges are built up to the given weight of the component.

2. Dial gauge with stand is placed on the surface plate.

3. The built up gauge is placed under the plunger.

4. The indicator is set to zero.

5. The built up gauge is removed.

6. The given machined component is placed under the plunger.

7. The variation in the height of the component is noted from the reading of the dial.

TABULATION: component height =____ mm.

Sl.

No

Dial reading on built up slip

Gauges in div.

Dial reading on

Component in div.

Variation of height

In mm

Calculation of Dial Gauge:-

Slip Gauge Reading Dial Gauge Reading

= 50+ …… = 0.2 + …….

= 51.001 mm = 0.2 + ……

= 51.003 mm = 0.2 + …….

Difference for the both should be equal

RESULT:

• The height of the machined component is checked with standard dimensioned Component

(slip gauges) using dial gauge.

• The variation in height is ________________ mm.



USE OF GEAR TEETH, VERNIER CALIPERS AND CHECKING THE

CHORDAL ADDENDUM AND CHORDAL HEIGHT OF SPUR GEAR.

Aim: To measure the tooth thickness of a given spur gear

Instruments Required: Gear vernier, Vernier caliper, Spur gear

Theory:

The tooth thickness is defined as the length of the arc of the pitch circle between opposite faces

of the same tooth. Most of the time a gear vernier is used to determine the tooth thickness. As

the tooth thickness varies from top to bottom, any instrument for measuring on a single

tooth.Gear tooth micro meter is used to measure the thickness of gear tooth at pitch line. It is

similar to simple micro meter but gear tooth micro meter having flanks at the end of anvil and

spindle. The flanks of the micro meter. Gives the thickness of gear tooth at pitch line.

Principle:-

Gear tooth micro meter works on the principle of screw and when screw is turned throughput

for one revolution it advances by one pitch distance i.e., one revolution of screw corresponds

to a linear moment of a distance equal to the pitch of thread.

Least Count (LC) = Pitch of the spindle screw/ No of divisions of the spindle (mm)

Terminology for Spur Gears:

Pitch surface: The surface of the imaginary rolling cylinder (cone, etc.) that the toothed gear

may be considered to replace.

Pitch circle: A right section of the pitch surface.

Addendum circle: A circle bounding the ends of the teeth, in a right section of the gear.

Root (or dedendum) circle: The circle bounding the spaces between the teeth, in a

right section of the gear.

Addendum: The radial distance between the pitch circle and the addendum circle.


Dedendum: The radial distance between the pitch circle and the root circle.

Clearance: The difference between the dedendum of one gear and the addendum of the

mating gear.

Face of a tooth: That part of the tooth surface lying outside the pitch surface.

Flank of a tooth: The part of the tooth surface lying inside the pitch surface.

Circular thickness (also called the tooth thickness): The thickness of the tooth

measured on the pitch circle. It is the length of an arc and not the length of a straight

line.

Tooth space: The distance between adjacent teeth measured on the pitch circle.

Backlash: The difference between the circle thickness of one gear and the tooth space

of the mating gear.

Circular pitch p: The width of a tooth and a space, measured on the pitch circle.

Diametral pitch P: The number of teeth of a gear per inch of its pitch diameter. A

toothed gear must have an integral number of teeth. The circular pitch, therefore, equals

the pitch circumference divided by the number of teeth. The diametral pitch is, by

definition, the number of teeth divided by the pitch diameter. That is,

and

Hence

p = circular pitch

P = diametral pitch

N = number of teeth

D = pitch diameter

That is, the product of the diametral pitch and the circular pitch equals .

Module m: Pitch diameter divided by number of teeth. The pitch diameter is usually

specified in inches or millimeters; in the former case the module is the inverse of

diametral pitch.

Fillet: The small radius that connects the profile of a tooth to the root circle.


Pinion: The smallest of any pair of mating gears. The largest of the pair is called simply

the gear.

Velocity ratio: The ratio of the number of revolutions of the driving (or input) gear to

the number of revolutions of the driven (or output) gear, in a unit of time.

Pitch point: The point of tangency of the pitch circles of a pair of mating gears.

Common tangent: The line tangent to the pitch circle at the pitch point.

Line of action: A line normal to a pair of mating tooth profiles at their point of contact.

Path of contact: The path traced by the contact point of a pair of tooth profiles.

Pressure angle : The angle between the common normal at the point of tooth contact

and the common tangent to the pitch circles. It is also the angle between the line of

action and the common tangent.

Base circle: An imaginary circle used in involute gearing to generate the involutes that

form the tooth profiles.

It should be noted that M is a chord AC, but the tooth thickness is specified as an arc

distance ADC. Also h is the distance EB and this is slightly greater than the addendum ED.


FORMULA USED:

Depth= (Zm/2) (1+2/Z-COS (90/Z)

Width=Zm x sin (90/Z)

Outer diameter of gear = (Z+2) m

Where,

Z-no of gear tooth, m-module

PROCEDURE:

1. Find the zero error in the horizontal scale and vertical scale of the given gear tooth vernier.

2. Find outer diameter of the given gear by using vernier caliper.

3. Count the no of tooth on the given gear.

4. Calculate the depth of pitch circle from the top circle.

5. Calculate the module (m) of the gear.

6. Similarly calculate the theoretical width by substituting and no of gear tooth in the formula.


7. The vertical gear tooth vernier is made of point the calculate the depth value.

8. Now the gear tooth, i.e. kept in between in the two jaws of the gear tooth vernier.

9. Observe the main scale reading and vernier scale coincidence of the horizontal scale.

10. Repeat the observation of different position of the same tooth and calculate the average.

Least count: Horizontal scale=0.02mm

Vertical scale =0.02mm

MODEL CALCULATION:

Module = outer dia/ (Z+2)

Depth = (Zm/2) (1+2/Z-COS (90/Z))

Width = Zm x sin (90/Z)

Deviation =theoretical value-actual value

RESULT:

Thus the thickness of the gear tooth of the given spur gear is calculated using gear tooth vernier.

Depth of the gear tooth = …………mm

Width of the gear tooth = …………mm

Theoretical value = ……………….mm

Actual value = ……………………mm


Experiment No: 5 Date: / / 20

ANGLE AND TAPER MEASUREMENTS BY BEVEL PROTRACTOR, SINE BARS

Aim: - To measure the taper angle of the given specimen using bevel protractor and sine bar

method.

APPARATUS REQUIRED:

1. Sine bar 2. Micrometer3. Slip gauge set 4. Surface plate5. Dial gauge withstand

6. Vernier caliper7.Combination Sets 8. Bevel Protector

Theory:

BEVEL PROTECTOR

A universal bevel protractor is used to measure angles between two planes. This consists of

stem, which is rigidly attached to main scale and a blade, which is attached to the Vernier

scale and can be rotated to read angles. To improve the accessibility, the blade can also slide.

The least count is calculated by knowing the value of the smallest division on the main scale

and number of division on the Vernier scale. It should be noted that the divisions on the main

scale is in degrees and that the fractional divisions of degrees are minutes (i.e. with 60

minutes/degree, denoted). To measure angle between two planes, rest the stem on one of the

planes (reference plane). Rotate the blade such that blade is flush with second plane.

Readings are taken after ensuring that the stem and blade are in flush with the two planes.

Lock the protractor at this point and note sown the readings.


OBSERVATIONS:

S.NO. ANGLE MEASURED

PRECAUTIONS:

1. The sine bar should not be used for angle greater than 600 because any possible error in

construction is accentuated at this limit.

2. A compound angle should not be formed by miss-aligning of work piece with the sine bar.

This can be avoided by attaching the sine bar and work against an angle plate.

3. As far as possible longer sine bar should be used since using longer sine bars reduces many

errors.

RESULT:

• The angle of the given specimen measured with the Bevel Protractor is…………………..

SINE BAR

The sine principle uses the ratio of the length of two sides of a right triangle in deriving a

given angle. It may be noted that devices operating on sine principal are capable of self-

generation. The measurement is usually limited to 45 degree from loss of accuracy point of

view. The accuracy with which the sine principle can be put to use is dependent in practice,

on some from linear measurement. The sine bar itself is not complete measuring instrument.

Another datum such as surface plate is needed, as well as other auxiliary instrument, notably

slip gauge, and indicating device to make measurements.

Sine bar:


A sine bar is a tool used to measure angles in metalworking.

FIG: SINE BAR

It consists of a hardened, precision ground body with two precision ground cylinders fixed at

each end. The distance between the centers of the cylinders is precisely controlled, and the

top of the bar is parallel to a line through the centers of the two rollers. The dimension

between the two rollers is chosen to be a whole number (for ease of later calculations) and

forms the hypotenuse of a triangle when in use. The image shows a 10 inch and a 100 mm

sine bar.

When a sine bar is placed on a level surface the top edge will be parallel to that surface. If

one roller is raised by a known distance then the top edge of the bar will be tilted by the same

amount forming an angle that may be calculated by the application of the sine rule.

The hypotenuse is a constant dimension — (100 mm or 10 inches in the examples

shown).

The height is obtained from the dimension between the bottom of one roller and the

table's surface.

The angle is calculated by using the sine rule.

Angles may be measured or set with this tool. For precision measurements where the bar

must be set at an angle, gauge blocks are traditionally used.

The sine bar is set up on a surface plate to the nominal angle of the taper plug, which is then

placed in position on the bar, being prevented from sliding down by the stop plate at the end.

Care must be taken to ensure that the axis of the plug gauge is aligned with the sine bar.

Pieces of “plasticine” will be found to be useful for preventing sideways movement. The dial

gauge, supported in a stand on the surface plate, is then passed over the plug gauge near each

end and also at one or two positions between the ends. If there is any variation in the

readings, two alternatives are available for finding the true angle of the cone. Either the

http://en.wikipedia.org/wiki/Metalworking

http://en.wikipedia.org/wiki/Image:SineBarStyles.jpg

http://en.wiktionary.org/wiki/hypotenuse

http://en.wikipedia.org/wiki/Surface_plate

http://en.wikipedia.org/wiki/Trigonometric_function#Right_triangle_definitions

http://en.wikipedia.org/wiki/Gauge_block


variation over a measured distance along the surface of the plug gauge can be used to obtain

the difference between the true angles or the angle set up, as the height of the slip gauge pile

can be adjusted until no variation occurs in the reading of the dial gauge.

Checking of Unknown Angles: - Many a times, angle of component to be checked is

unknown. In such a case it is necessary to first find the angle approximately with the help of a

bevel protractor. Let the angle. Then the sine bar is set at an angle () and clamped to an angle

plate. Next the work is placed on sine bar and clamped to Angle plate as shown in figure. Slip

–gauges are so arranged (according to deviation) that the sprit level is at center (the air

bubble)

If the deviation is noted down by the spirit level is h over a length ‘l’ of work ,then height of

slip gauges by which it should be adjusted is equal to = h 1

FORMULA:

Sin Ø = h / L

Where,

H - Height of the slip gauge

L - Distance between the centres

Ø - Inclined angle of the specimen

PROCEDURE:

• The given component is placed on the surface plate.

• One roller of sine bar is placed on surface plate and bottom surface of sine bar is seated on

the taper surface of the component.

• The combination of slip gauges is inserted between the second rollers of sine bar and the

surface plate.

• The angle of the component is then calculated by the formula given above.

S.No Length of the sine

bar (L) mm

Height

(h)mm

Taper angle (ϴ)


CALCULATION:

Sin Ø = h / L

Precaution in Sine Bars:-

(a) A Compound angle should not be formed by miss dignity of w/p with the sine bar. This

can be avoided by attaching the sine brand work against an angle plate.

(b) Accuracy of sine bar should be ensured.

(c) As far as possible longer sine bar should be used since4 many errors are reduced by using

longer sine bar.

Precautions:-

1. Angle of instrument must coincide with the angular scale

2. Gripped the instrument to the measuring face exactly

Result:-

Thus the taper angle of the given specimen is measured using sine bar.

The external taper angle is……………………………………..

VIVA – QUESTIONS

1. What is the use of angle plates?

2. Name some angle measuring devices?

3. What is the least count of mechanical Bevel Protractor?

4. What is the least count of optical Bevel Protractor?

5. What is a sine bar?

6. What are the limitations of Sine bar?

7. What is the difference between the sine bar and sine center?

8. What is the use of V-block?

9. What is the purpose of adjusting nuts in a micro meter?

10. What is the least count of dial indicator?

11. How do you specify sine bar?

12. How to maintain constant pressure in micro meter?

13. What are the applications of Gear toothvernier caliper?

14. How do we check the profile of a Gear tooth?

15. Name some angle measuring devices?

16. Why do we use Feeler gauges?


17. What are slip gauges and why do we use them?

18. What are slip gauges and why do we use them?

19. Explain zero error and zero correction in case of micrometers?

20. What is the principle involved in sprit levels?

21. What is the least count of digital vernier caliper?

22. What is the difference between vernier height gauge, vernier depth gauge, and vernier

caliper?

23. Explain briefly about the different types of micrometers?



MACHINE TOOL “ALIGNMENT TEST ON THE LATHE.

Aim:-

1. Test for level of installation:

(a) In a longitudinal b) In transverse direction

Measuring instruments: Spirit level, gauge block to suit the guide ways of the lathe bed.

Theory:-

The following are the alignment tests on lathe.

Levelling of machine:-

It is essential that a machine tool should be installed truly horizontal and vertical plane and this

accuracy must be maintained. The level of machine base in longitudinal and transverse

direction is tested by spirit level or precision level. The spirit level is placed at to measure the

level.

True running of main spindle:-

The true mandrel is placed in the main spindle and test is conducted on the surface of material

if dial gauge shows any deviation in the reading then it is said that the main spindle is running

in the proper way.

Parallelism of main spindle to saddle movement:-

If the axis of the spindle is not parallel to the saddle movement then it is not possible to get

required dimension of work piece while doing the operation on lathe. The spindle is moved

and the deviation in the reading of dial gauge are noted.

Parallelism of Tailstock guide ways to saddle movement:-

To check the parallelism of guide ways with the saddle movement in the both vertical and

horizontal directions. The dial indicator is held on the spindle and block is moved

simultaneously any deviation in reading of dial gauge is noted if no deviation in the reading

then tail stock guide ways is parallel to saddle movement otherwise it is not parallel to saddle

movement.

Parallelism of tail stock guide ways to carriage movement:-

To check the parallelism of guide ways with the carriage in both vertical and horizontal

objections. A block is placed on the guide ways of tail stock. The dial indicator is held on the

carriage and block is moved simultaneously any deviation in reading of dial gauge is noted

Parallelism of main spindle to carriage movement:-

To check the parallelism of main spindle to carriage in both vertical and horizontal. The

deviation is observed the spindle is not parallel to the carriage.


True Running of head stock centre:-

The test mandrel is placed in the head stock and test is conducted on the surface of carriage.

The dial gauge shows any deviations in the reading then the head stock is not running in proper.

Procedure: - The gauge block with the spirit level is placed on the bed ways on the front

position, back position and in the cross wise direction. The position of the bubble in the spirit

level is checked and the readings are taken.

1. Permissible error: Front guide ways. 0.02 mm/meter convex only. Rear guide ways, 0.01

to0.02 convexity. Bed level in cross-wise direction ±0.02/meters. Straightness of slide ways(for

machines more than 3 mm turning length only, measurement taken by measuring tight wire

and microscope or long straight edge). Tailstock guide ways parallel with movement of

carriage 0.02 mm/m. No twist is permitted.

The error in level may be corrected by setting wedges at suitable points under the support feel

or pads of the machine.

2. Straightness of saddle in horizontal plane:-

Measuring instruments: Cylindrical test mandrel (600mm long), dial indicator.

Procedure: - The mandrel is held between centres. The dial indicator is mounted on the saddle.

The spindle of the dial indicator is allowed to touch the mandrel. The saddle is then moved

longitudinally along the length of the mandrel. Readings are taken at different places.

Permissible error: 0.02 mm over length of mandrel.

3. Alignment of both the centres in the vertical plane:

Measuring instruments: Cylindrical mandrel 600 mm long, dial gauge.

Procedure: The test mandrel is held between centres. The dial indicator is mounted on the

saddle in vertical plane as shown in figure. Then the saddle along with the dial gauge is

travelled longitudinally along the bed ways, over the entire length of the mandrel and the

readings are taken at different places.

Permissible error: 0.02 mm over 600 mm length of mandrel (Tail stock centre is to lie higher

only).


4. True running of taper socket in main spindle

Instruments required: Test mandrel with taper shank and 300 mm long cylindrical measuring

part, dial gauge.

Procedure: The test mandrel is held with its taper shank in a head stock spindle socket. The

dial gauge is mounted on the saddle. The dial gauge spindle is made to touch with the mandrel.

The saddle is then travelled longitudinally along the bed ways and readings are taken at the

points A and B as shown in figure.

Permissible error: Position A 0.01 mm, position B 0.02 mm.

5. Parallelism of main spindle to movement:

(a) In a vertical plane (b) In a horizontal plane

Measuring instruments: Test mandrel with taper shank and 300 mm long cylindrical

measuring part, dial gauge.

Procedure: The dial gauge is mounted on the saddle. The dial gauge spindle is made to touch

the mandrel and the saddle is moved to and fro. It is checked in vertical as well as in horizontal

plane.

Permissible error: (a) 0.02/300 mm mandrel rising towards free end only.

(b) 0.02/300 mm mandrel inclined at free end towards tool pressure only.

6. Movement of upper slide parallel with main spindle in vertical plane:

Measuring instruments: Test mandrel with taper shank and 300 mm long cylindrical

measuring part, dial gauge.

Procedure: The test mandrel is fitted into the spindle and a dial gauge clamped to the upper

slide. The slide is transversed along with the dial gauge plunger on the top of the stationary

mandrel.


Permissible error: 0.02 mm over the total movement of the slide.

7. True running of locating cylinder of main spindle:

Measuring instrument: Dial gauge.

Procedure: The dial gauge is mounted on the bed, touching at a point on main spindle. The

main spindle is rotated by hand and readings of dial gauge are taken.

Permissible error: 0.01 mm.

8. True running of head stock centre:

Measuring instruments: Dial gauge.

Procedure: The live centre is held in the tail stock spindle and it is rotated. Its trueness is

checked by means of a dial gauge.

Permissible error: 0.01 mm.

9. Parallelism of tailstock sleeve to saddle movement:

Measuring instruments: Dial indicator

Procedure: Tailstock sleeve is fed towards. The dial gauge is mounted on the saddle. Its

spindle is touched to the sleeve at one end and the saddle is moved to and fro, it is checked in

H.P. and V.P. also.

Permissible error: (a) 0.0 1/100 mm (Tailstock sleeve inclined towards tool pressure only).

(b) 0.0 1/100 mm (Tailstock sleeve rising towards free end only).


10. Paralle1ism of tail stock sleeve taper socket to saddle movement

(a) In V.P.

(b) In H.P.

Measuring instruments: - The mandrel with taper shank and a cylindrical measuring part of

300mm length, dial gauge.

Procedure: - Test mandrel is held with its taper shank in tail-stock sleeve taper socket. The

dial gauge is mounted on spindle. The dial gauge spindle is made to touch with the mandrel.

The saddle is then transverse longitudinally along the bed way and readings are taken.

Permissible error:-

(a) 0.03/300 mm (mandrel rising towards free end only).

(b) 0.03/300 mm (Mandrel inclined towards tool pressure only).

PRECAUTIONS:

i) The mandrel must be so proportioned that its overhang does not produce appreciable sag,

else the sag must be calculated and accounted for.

ii) The indicator set up must be rigid, otherwise variations in readings as recorded by point may

be solely due to deflection of the indicator.

REVIEW QUESTIONS

a) What is the necessity of conducting various alignment tests on lathe?

b) What are the various alignment tests to be conducted on the lathe?

c) What is straightness?

d) What is flatness?

e) What is square ness?

f) What is parallelism?

g) What do you mean by axial slip of main spindle?

h) It is necessary to conduct alignment tests on other machine tools? If so why? Not, why not?


CYCLE-2 EXPERIMENTS



MACHINE TOOL ALIGNMENT TEST ON MILLING MACHINE.

Aim:-

To perform the alignment test on milling.

Apparatus:-

Spirit level, gauge blocks, dial gauge

Theory:-

Following are the tests on milling machine

Test for levelling of milling machine:-

It is essential that a machine tool should be installed truly horizontal and vertical plane and this

accuracy must be maintained. If milling base is not installed truly horizontal then bed will

undergo a deflection and produce a simple bend.

True Running of spindle:-

A mandrel placed in the spindle and test is conducted on the surface of mandrel. A dial gauge

is fixed on the machine table and feeler of the dial gauge is made to touch the lower surface of

it clearance is noted then it is said that the table is not flat otherwise it is flat.

True Running of spindle:-

For this test the mandrel is placed in the spindle and dial indicator is fixed on the table. The

feeler of dial gauge is made to touch the surface of manderal.

Parallelism of spindle Axis with its vertical moment:-

For this test the manderal is placed in the spindle and dial indicator is fixed on the table. The

feeler of dial gauge is made to touch the surface of mandrel also moved up and down, the

mandrel also moved up and down observe any direction in the reading of dial gauge is noted

then that is said that it is not running in proper way mandrel. Axis slip of main spindle is

developed due to the error in bearing support for this test feeler of the dial gauge is placed on

the face of main spindle and the dial gauge.

Parallelism (or) Table Surface with longitudinal surface:-

A machine is placed in the spindle and test is conducted on the surface of mandrel. If any

degration is noted then it is noted then it is said that spindle is not parallel to the table.

Parallelism of Table Surface with main spindle:-

A mandrel is placed in the spindle and test is conducted on the surface of mandrel. A dial gauge

is fixed on the table and feeler is touched to the spindle. If any deviation takes place the spindle

is not machine to the table.


Parallelism of Table Surface with Arbor:-

Arbor is placed in the spindle and test is conducted on the surface of order. If any degration is

noted than it is said that arbor is not parallel to the table.

Procedure:

(1) Flatness of work table

(a) In longitudinal direction.

(b) In transverse direction.

Measuring instruments: - Spirit level.

Procedure: - A spirit level is placed directly on the table at points about 25 to 30 cm apart, at

A, B, C for longitudinal tests and D, E and F for the transverse test. The readings are noted.

Permissible error:

Direction A-B-C, ± 0.04 mm

Direction D-E-F, ± 0.04 mm

(2) Parallelism of the work table surface to the main spindle

Measuring instruments: Dial indicator, test mandrel 300 mm long, spirit level.

Procedure: The table is adjusted in the horizontal plane by spirit level and is then set in its

mean position longitudinally. The mandrel is fixed in the spindle taper. The dial gauge is set

on the machine table, and the feeder adjusted to touch the lower surface of the mandrel. The

dial gauge readings at (A) and (B) are observed, the stand of the dial gauge being moved while

the machine table remains stationary’.

Permissible error: 0.02/3 00 mm.


(3) Parallelism of the clamping surface of the work table in its longitudinal motion:

Instruments: Dial gauge, straight edge.

Procedure: A dial gauge is fixed to the spindle. The dial gauge spindle is adjusted to touch the

table surface. The table is then moved in longitudinal direction and readings are noted. If the

table surface is uneven it is necessary to place a straight edge on its surface and the dial gauge

feeder is made to rest on the top surface of the straight edge.

Permissible error: 0.02 up to 500 mm length of transverse, 0.03 up to 1000 mm and 0.04

above1000 mm length of transverse.

(4) Parallelism of the cross (transverse) movement of the worktable to the main spindle

:( a) In vertical plane

(b) In horizontal plane

Instruments: Dial gauge, test mandrel with taper shank.

Procedure: The work table is set in its mean position. The mandrel is held in the spindle. A

dial gauge fixed to the table is adjusted so that its spindle touches the surface of the mandrel.

The table is moved cross-wise and the error is measured in the vertical plane and also in the

horizontal plane.

Permissible error: 0.02 for the overall transverse movement of the work table.

(5) True running of internal taper of the spindle:

Instruments: 300 mm long test mandrel, dial gauge.


Procedure: The test mandrel with its taper shank is held in the main spindle. Dial gauge is

kept scanning the periphery of the mandrel. Spindle is rotated and dial gauge readings are noted

at different points say A and B as shown.

Permissible error: Position A: 0.01 mm, Position B: 0.02 mm.

(6) Square nests of the centre T-slot of worktable with main spindle

Instruments: Dial gauge, special bracket.

Procedure: To check the perpendicularity of the locating slot and the axis of the main spindle.

The table should be arranged in the middle position of its longitudinal movement, and a bracket

with a tenon at least 150 mm long inserted in the locating slot as shown in figure. A dial gauge

should be fixed in the taper, the feeder being adjusted to touch the vertical face of the bracket.

Observe the reading on the dial gauge when the bracket is near one end of the table, the swing

over the dial gauge and move the bracket so that the corresponding readings can be taken near

the other end of the table.

Permissible error: 0.025 mm in 300 mm.

(7) Parallelism of the T-slot with the longitudinal movement of the table:

Instruments: Dial gauge, special bracket.

Procedure: The general parallelism of the T-slot with the longitudinal movement of the table

is checked by using 150 mm long braked having a tenon which enters the slot, the dial gauge

is fixed to the spindle taper and adjusted so that its feeder touches the upper surface of the

bracket. The table is then moved longitudinally while the bracket is held stationary by the hand

of the operator and dial gauge deviations from parallelism are note down.

Permissible error: 0.0 125 mm in 300 mm.


(8) Parallelism between the main spindle and guiding surface of the overhanging arm

Instruments: Dial gauge, mandrel.

Procedure: The overhanging arm is clamped in its extreme extended position. The dial

gauge is fixed to the arbor support. The feeder of the dial gauge is adjusted to touch the

top or ride of the test mandrel. The arbor can then be moved along the overhanging arm

and the deviations from parallelism observed on the dial gauge.

PRECAUTIONS:

i) All moving parts of the machine must be locked while reading the dial gauge,

ii) If the table surface is uneven, straight edges must be used.

REVIEW QUESTIONS:

i) Distinguish between geometric tests and practical tests.

ii) How will you measure the flatness of the table surface?

iii) What are the various alignment tests conducted on vertical milling machine?

iv) What are the various measuring instruments used in alignment test of a milling

machine

v) What are the dimensions of a test piece used in practical test?



TOOL MAKER’S MICROSCOPE AND ITS APPLICATION.

Aim:-

Study of Tool Maker’s Microsocope.

Objectives:

After performing this experiment, you should be able to

• appreciate the importance of precision measurement,

• know how precise measurements can be taken with this instrument,

• explain the field of application/working of this instrument, and

• understand the principle of working of tool room microscope.

Introduction:

Engineering microscopes designed to satisfy various measuring needs of toolmakers are known

as toolmaker’s microscopes. A plain toolmaker’s microscope is primarily intended for a

particular application. On the other hand, universal toolmaker’s microscope is adaptable to an

uncommonly wide range of measuring tasks. A toolmaker’s microscope is designed for

measurements of parts of complex forms, e.g. profile of external threads, tools, templates and

gauges. It can also be used for measuring centre‐to‐centre distance of holes in any planes, as

well as the co‐ordinate of the outline of a complex template gauges.

Apparatus:-

Tool maker’s microscope, specimen

FIG: TOOL MAKERS MICROSCOPE


BRIEF DESCRIPTION OF INSTRUMENT:

It consists of optical head, which can be adjusted vertically along the ways of the vertical

column and can be clamped in any position. The working table is secured on a heavy hollow

base. The table has a compound slide to give longitudinal and lateral movements actuated by

accurate micrometre screws having thimble scales and vernier. At the back of the base is a light

source, which provides a horizontal beam of light reflected upwards by 90otowards the table.

This beam of light passes through a transparent glass plate on which flat parts to be checked

are placed. A shadow image of the outline of the contour passes the objective of the optical

head and is projected by a combination of three prisms to a ground glass screen. Observations

are made through the eyepiece of the optical head. Figure gives the views of a tool room

microscope. Cross lines are engraved on the glass screen, which can be rotated through 360o,

and these lines make the measurements. The angle of rotation of screen can be read on the

optical head. The eyepiece field of view contains an illuminated circular scale with a division

value of one minute. Adjusting optical head tube performs focussing.

Theory:-

The tool maker microscope is designed for measurement of components of difficult forms.

Ex: - profile of external threads, tools, gauge. It can be used for measuring center to center

distance of holes in any plane it consists of optical head which can be adjusted vertically along

inspection the table can be moved in longitudinal direction and lateral direction by micro meter

screws, which are having barrel and thimble at back of base light is arranged which provides

on the optical head. The image of component passes through optical head and observations.

The reading of longitudinal micro meter is noted. The difference gives the pitch of the thread.

FIG: TOOL MAKERS MICROSCOPE


Procedure:-

PROCEDURE:

1. Switch on the main.

2. Switch on the micros scope lights.

3. Select the capacity of the lens for precision operation.

4. Place the object on the class table to get the clear image rotate the wheel provided at the light

side.

5. After getting the clear image, locate the crosswire at the initial point on the image. Now note

down the micro meter reading.

6. Move the cross wire from initial point to the finial point on the image, which is to be

measured. Note down the micro meter reading, this operation is done by usingmicrometer.

7. Now the different but when the initial and the finial reading i.e. distance travelled gives the

size of the object.

8. Graph can be plotted actual micro meter reading vs. % of error.

Precautions:-

1) Obtain clean picture of cross line and the cross thread seen through the eyepiece.

2) For angular measurements lines must remain parallel to flank edge to the tooth.

RESULT:

Thus the all dimensions of the given particular screw were measured by using toolmaker’s

microscope.



USE OF SPIRIT LEVEL IN FINDING THE FLATNESS OF SURFACE

PLATE.

Aim:-

To check the flatness of given surface plate

Apparatus:-

Spirit level, surface plate

Theory:-

Generally spirit level is used for levelling the machinery and other instruments. But spirit levels

are also used to measure the angles. It is also called precision level. It consists of glass tube

and of the tube. If the tube is fitted through a small angle if R- radius of tube L distance of

bubble moved when spirit level is fitted to same angle

The simplest form of flatness testing is possible by comparing the surface with an accurate

surface. Spirit level is used in special cases and called Clinometers, precision micro-optic

clinometers utilizes bubble unit with a prismatic coincidence reader which presents both ends

of the bubble an adjacent images in a spirit field.Leveling helps in the coincidence of the 2

images, making it very easy to sec when the bubble is exactly centered without reference to

any graduations. The special features to precision micro-optic clinometers arc direct reading

over range 0-360°, optically reading system, main coarse setting, slow motion screw to fine

setting. The least count of precision spirit level is 0.01 mm.

The spirit of level consists of a sealed glass tube mounted on a base. The inside surface of the

tube is ground to a convex barrel shape having large radius. The precision of the level depends

on the accuracy of this radius of the tube. A scale is engraved on the top of the glass tube. The

tube is nearly filled with either ether or alcohol, except a small air or vapour in the form of a

bubble.

The bubble always tries to remain at the highest point of the tube. If the base of the spirit level

is horizontal, the centre point is the highest point of the tube. So, that when the level is placed

on a horizontal surface, the bubble rests at the centre of the scale. If the base of the level is

fitted through a small angle, the bubble will more relative to the tube a distance along its radius

corresponding to the angle.

Fig: surface plate Fig: Spirit level


The figure shows two positions of the base of the level (OA1 and OA2) and corresponding

positions of the bubble (Bl, B2). When the base OA1 is horizontal, the bubble occupies

positionB1. Let ‘ϴ‘be the small angle through which the base is fitted. The bubble now

occupies the position B2.Let L be the distance travelled by bubble along the tube and ‘h’ the

difference in heights between the ends of the base. Then L= Rϴ and h =. Lϴ

Therefore ϴ =𝟏

𝑹=

𝒉

𝑳

Therefore 𝟏 = 𝒉𝑹

𝑳

Where R = radius of curvature of the tube

L = length of base

Finally 𝒉 =𝑳

𝑹

Procedure:

1 Place the spirit level on the surface plate for which we have to find out the flatness

2 Find the base length of the spirit level

3 Note the radius of curvature of the spirit level tube

4 Find the tilt in the bubble

5 Finally find out the difference in heights between the ends of the base.

Flatness of the specimen:

S.NO Distance travelled

by the bubble

Difference in height

between

ends

Angle

‘ϴ’

1

2

3

4

5

Precautions:

1 .Clean the surface plate and ensure there is no dust particles

2. Take the bubble reading without any parallax error.

Result:-The experiment has been conducted on spirit level to check the flatness of given

surface plate. The given surface plate is flat/not flat---------------------



THREAD MEASUREMENT BY TWO/THREE WIRE METHOD OR

TOOL MAKERS’ MICROSCOPE.

Aim:-

To measure the effective diameter of the screw thread by using two/three wire method or Tool

makers’ microscope

Apparatus:-Tool Maker’s Microscope

Theory:-

1. Screw thread. A screw thread is the helical ridge produced by forming a continuous helical

groove of uniform section on the external or internal surface of a cylinder or cone. A screw

thread formed on a cylinder is known as straight or parallel screw thread, while the one formed

on a cone or frustum of a cone is known as tapered screw thread.

2. External thread. A thread formed on the outside of a work piece is called external thread

e.g., on bolts or studs etc.

3. Internal thread. A thread formed on the inside of a work piece is called internal thread e.g.

on a nut or female screw gauge.

4. Multiple-start screw thread. This is produced by forming two or more helicalgrooves,

equally spaced and similarly formed in an axial section on a cylinder. This gives a ‘quick

traverse’ without sacrificing core strength.


5. Axis of a thread. This is imaginary line running longitudinally through the centre of the

screw.

6. Hand (Right or left hand threads). Suppose a screw is held such that the observer is

looking along the axis. If a point moves along the thread in clockwise direction and thus moves

away from the observer, the thread is right hand; and if it moves towards the observer, the

thread is left hand.

7. Form, of thread. This is the shape of the contour of one- complete thread as.seen in axial

section.

8. Crest of thread. This is defined as the prominent part of thread, whether it be external or

internal.

9. Root of thread. This is defined as the bottom of the groove between the two flanks of the

thread, whether it be external or internal.

10. Flanks of thread. These are straight edges which connect the crest with the root.

11. Angle of thread {Included angle). This is the angle between the flanks or slope of the

thread measured in an axial plane.

12. Flank angle. The flank angles are the angles between individual flanks and the

perpendicular to the axis of the thread which passes through the vertex of the fundamental

triangle. The flank angle of a symmetrical thread is commonly termed as the half- angle of

thread.

13. Pitch. The pitch of a thread is the distance, measured parallel to the axis of the thread,

between corresponding points on adjacent thread forms in the same axial plane and on the same

side of axis. The basic pitch is equal to the lead divided by the number of thread starts. On

drawings of thread sections, the pitch is shown as the distance from the centre of one thread

crest to the centre of the next, and this representation is correct for single start as well as multi-

start threads.

14. Lead. Lead is the axial distance moved by the threaded part, when it is given one complete

revolution about its axis with respect to a fixed mating thread. It is necessary to distinguish

between measurements of lead from measurement of pitch, as uniformity of pitch measurement

does not assure uniformity of lead. Variations in either lead or pitch cause the functional or

virtual diameter of thread to differ from the pitch diameter.

15. Thread per inch. This is the reciprocal of the pitch in inches.

16. Lead angle. On a straight thread, lead angle is the angle made by the helix of the thread at

the pitch line with plane perpendicular to the axis. The angle is measured in an axial plane.

17. Helix angle. On straight thread, the helix angle is the angle made by the helix of the thread

at the pitch line with the axis. The angle is measured in an axial plane.

18. Depth of thread. This is the distance from the crest or tip of the thread to the root of the

thread measured perpendicular to the longitudinal axis or this could be defined as the distance

measured radially between the major and minor cylinders.


19. Axial thickness. This is the distance between the opposite faces of the same thread

measured on the pitch cylinder in a direction parallel to the axis of thread.

20. Fundamental triangle. This is found by extending the flanks and joining the points and C.

Thus in Fig. 13.2, triangle ABC is referred to as fundamental triangle.

Here BC=pitch and the vertical height of the triangle is called the angular or theoretical depth.

The point A is the apex of the triangle ABC.

21. Truncation. A thread is sometimes truncated at the crest or at the root or at both crest and

root. The truncation at the crest is the radial distance from the crest to the nearest apex of the

fundamental triangle. Similarly the truncation at the root is the radial distance from the root to

the nearest apex.

22. Addendum. For an external thread, this is defined as the radial distance between the major

and pitch cylinders. For an internal thread this is the radial distance between the minor and

pitch cylinders.

23. Dedendum. This is the radial distance between the pitch and minor cylinder for external

thread, and for internal thread, this is the radial distance between the major and pitch cylinders.

24. Major diameter. In case of a straight thread, this is the diameter of the major cylinder

(imaginary cylinder, co-axial with the screw, which just touches the crests of an external thread

or the root of an internal thread). It is often referred to as the outside diameter, crest diameter

or full diameter of external threads.

25. Minor diameter. In case of straight thread, this is the diameter of the minor cylinder (an

imaginary cylinder, co-axial with the screw which just touches the roots of an external thread

or the crest of an internal thread). It is often referred to as the root diameter or cone diameter

of external threads.

26. Effective diameter or pitch diameter. In case of straight thread, this is the diameter of

the pitch cylinder (the imaginary’ cylinder which is co-axial with the axis of the screw, and

intersects the flank of the threads in such a way as to make the width of threads and width of

the spaces between the threads equal). If the pitch cylinder be imagined as generated by a

straight line parallel to the axis of screw that straight line is then referred to as the pitch line.

Along the pitch line, the widths of the threads and the widths of the spaces are equal on a

perfect thread. This is the most important dimension at it decides the quality of the fit between

the screw and the nut.

27. Functional (virtual) diameter. For an external or internal thread, this is the pitch diameter

of the enveloping thread of perfect pitch, lead and flank angles having full depth of engagement

but clear at crests and roots. This is defined over a specified length of thread. This may be

greater than the simple effective diameter by an amount due to errors in pitch and angle of

thread. The virtual diameter being the modified effective diameter by pitch and angle errors, is

the most important single dimension of screw thread gauge.

(i) Measurement of Major Diameter.

For the measurement of major diameter of external threads, a good quality hand micrometers

is quite suitable. In taking readings, a light pressure must be used as the anvils make contact

with the gauge at points only and otherwise the errors due to compression can be introduced.


It is, however, also desirable to check the micrometers reading on a cylindrical standard of

approximately the same size, so that the zero error etc., might not come into picture.

For greater accuracy and convenience, the major diameter is measured by bench micrometers.

This instrument was designed by N.P.L. to estimate some deficiencies inherent in the normal

hand micrometers. It uses constant measuring pressure and with this machine terror due to pitch

error in the micrometers thread is avoided. In order that all measurements be made at the same

pressure, a fiducially indicator is used in place of the fixed anvil. In this machine there is no

provision for mounting the work piece between the centres and it is to be held in hand. This is

so, because, generally the centres of the work piece are not true with its diameter. This machine

is used as a comparator in order to avoid any pitch errors micrometers, zero error setting etc.

A calibrated setting cylinder is used as the setting standard.

The advantage of using cylinder as setting standard and not slip gauges etc., is that it gives

greater similarity of contact at the anvils. The diameter of the setting cylinder must be nearly

same as the major diameter. The cylinder is held and the reading of the micrometers is noted

down. This is then replaced by threaded work piece and again micrometers reading is noted for

the same reading of fiducially indicator. Thus, if the size of cylinder is approaching, that of

major diameter, then for a given reading the micrometers thread is used over a short length of

travel and any pitch errors it contains are virtually eliminated.

Then major diameter=D1+ (R2−R1).

In order- to determine the amount of taper, the readings should’ be taken at various positions

along the thread and to detect the ovality, two or three readings must be taken at one plane in

angular positions.

(ii) Measurement of Minor Diameter

This is also measured by a comparative process using small Vee-pieces which make contact

with a root of the thread. The Vee-pieces are available in several sizes having suitable radii at

the edges. The included angle of Vee-pieces is less than the angle of the thread to be checked


so that it can easily probe to the root of the thread. To measure the minor diameter by Vee-

pieces is suitable for only Whitworth and B.A. threads which have a definite radius at the root

of the thread. For other threads, the minor diameter is measured by the projector or microscope.

The measurement is carried out on a floating carriage diameter measuring machine in which

the threaded work-piece is mounted between centres and a bench micrometers is constrained

to move at right angles to the axis of the centre by a Vee-ball slide. The method of the

application of Vee-pieces in the machine is shown diagrammatically in Fig... The dimensions

of Vee-pieces play no important function as they are interposed between the micrometers faces

and the cylindrical standard when standard reading is taken.

It is important while taking readings, to ensure that the micrometers be located at right angles

to the axis of the screw being measured. The selected Vees are placed on each side of the screw

with their bases against the micrometers faces. The micrometers head is then advanced until

the pointer of the indicator is opposite the zero mark, and note being made of the reading. The

screw is then replaced by standard reference disc or a plain cylindrical standard plug gauge of

approximately the core diameter of the screw to be measured and second reading of the

micrometers is taken.

If reading on setting cylinder with Vee-pieces in position=R1

And reading on thread =R2

And diameter of setting cylinder=D1

Then minor diameter =D1+ (R2—R1)

Readings may be taken at various positions in order to determine the taper and joviality.

(iii) Effective Diameter Measurements.

The effective diameter or the pitch diameter can be measured by any one of the following

methods:

(i) The micrometre method

(ii) The one wire, two wire, or three wire or rod method.


Procedure:

1. Two Wire Method.

The effective diameter of a screw thread may be ascertained by placing two wires or rods of

identical diameter between the flanks of the thread, as shown in Fig. 13.15, and measuring the

distance over the outside of these wires. The effective diameter E I s then calculated as

E=T+P

Where T= Dimension under the wires

=M—2d

M=dimension over the wires, d= diameter of each wire

Fig (a) Fig (b)

The wires used are made of hardened steel to sustain the wear and tear in use. These are given

a high degree of accuracy and finish by lapping to suit different pitches. Dimension T can also

be determined by placing wires over a standard cylinder of diameter greater than the diameter

under the wires and noting the reading R1 and then taking reading with over the gauge, say R2.

Then T=S—(R1—R2).

P=It is a value which depends upon the dia of wire and pitch of the thread.

If P= pitch of the thread, then

P= 0.9605p−1.1657d (for Whitworth thread).

P= 0.866p—d (for metric thread).

Give the effective diameter. The expression for the value of P in terms of p (pitch), d

(Diameter of wire) and x (thread angle) can be derived as follows:

In Fig.13.15 (b), since BC lies on the effective diameter line

BC= ½ pitch=½ p


OP=d cosec x/2∕2

PA=d (cosecx∕2−1) ∕2

PQ=QC cot x∕2=p∕4 cot x∕2

AQ=PQ−AP=p cot x∕2∕4 – d (cosec x∕2 −1) ∕2

AQ is half the value of P

.’. P value=2AQ

=p∕2 cot x∕2 −d (cosecx∕2−1)

Two wire method can be carried out only on the diameter measuring machine described for

measuring the minor diameter, because alignment is not possible by 2 wires and can be

provided only by the floating carriage machine. In the case of three wire method, 2wire, on one

side help in aligning the micrometre square to the thread while the third placed on the other

side permits taking of readings.

2. Three Wire Method.

This method of measuring the effective diameter is an accurate method. In this three wires or

rods of known diameter are used; one on one side and two on the other side {Fig.13.17 (a) and

(&)]. This method ensures the alignment of micrometre anvil faces parallel to the thread axis.

The wires may be either held in hand or hung from a stand so as to ensure freedom to the wires

to adjust themselves under micrometre pressure.

M=distance over wires E=effective diameter

r=radius of the wires d=diameter of wires

h =height of the centre or the wire or rod from the effective

x=angle of thread.

Fig: a fig: b

From fig. (b),

AD = AB cosec x∕2 = r cosec x∕2

H = DE cot x∕2 = p∕2 cot x∕2

CD = ½H = p∕4 cot x∕2

H = AD−CD

r = cosec x∕2− p∕4 cot x∕2


Distance over wires=M = E+2h+2r

= E+2(r cosec x∕2 – p∕4 cot x∕2) +2r

= E+2r (louse x∕2) − p∕2 cot x∕2

Or M = E+d (1+cosec x∕2) − p∕2 cot x∕2

(Since 2r = 0)

(i) In case of Whitworth thread:

X = 55°, depth of thread = 0.64 p, so that

E= D—0.64 p and cosec x∕2 = 2.1657

Cot x∕2 = 1.921

M = E+d (1+cosec x∕2) — p∕2 cot x∕2

= D−0.64p+d (1+2.1657) −p∕2 (1.921)

= D+3.1657d−1.6005p

M = D+3.1657d—1.6p

Where D=outside dia.

(ii) In case of metric threads:

Depth of thread=0.6495p

So, E = D-0.6495p.

x = 60°, cosec x∕2 = 2; cot x∕2 = 1.732

M = D−0.6495 p+d (l+2)—p∕2 (1.732)

= D+3d−(0.6495+0.866)p

= D+3d—1.5155p.

Result:

B) TOOL MAKERS’ MICROSCOPE:

Procedure:

1. Switch on the main.

2. Switch on the micros scope lights.

3. Select the capacity of the lens for precision operation.

4. Place the object on the class table to get the clear image rotate the wheel provided at the light

side.


5. After getting the clear image, locate the crosswire at the initial point on the image. Now note

down the micrometre reading.

6. Move the cross wire from initial point to the finial point on the image, which is to be

measured. Note down the micrometre reading, this operation is done by using micrometre.

7. Now the different but when the initial and the finial reading i.e. distance travelled gives the

size of the object.

8. Graph can be plotted actual micrometre reading vs. % of error.

TABULATION:

Sl.

No

Actual

micrometre

reading in mm

(A)

Profile projector micrometre reading

Error

(A-D)

In

mm

% error

Initial(B)

mm

Final (c) mm

Difference

b/w B& C (D)

CALCULATION:

% error = (error/actual micrometre reading) x100

FIND THE FLANK ANGLE:

Sl.

No

Initial angle in degree

(A)

Final angle in

degree (B)

Difference b/w

(A&B)

Average

RESULT:

Thus the all dimensions of the given particular screw were measured by using tool maker’s

microscope.


Experiment No: 11

SURFACE ROUGHNESS MEASUREMENT BY TALY SURF

Aim: To measure the surface roughness using Taly surf instrument.

Apparatus: - Taly surf, work piece, surface plate.

Theory:

On any finished surface, imperfections are bound to be there and these take the form of a

succession of hills and valleys which vary both in height and in spacing and result in a kind of

texture which in appearance or feel is often characteristic of the machining process and

accompanying defects. The several kinds of departures are there on the surface and these are

due to various causes.

Methods of Measuring Surface Roughness:

•Surface inspection of comparison methods

•Direct instrument measurements

In comparative methods the surface texture is assessed by observation of the surface. But these

methods are not reliable as they can be misleading, if comparison is not made with surfaces

produced by same techniques. The various methods available under comparison method are:

(i) Touch Inspection (ii)Scratch Inspection (iii) Microscopic Inspection (iv) Visual Inspection

(v) Surface Photographs (vi) Reflected Light Intensity Direct Instrument Measurements enable

to determine a numerical value of the surface finish of any surface. Nearly all instruments used

are stylus probe type of instruments. These operate on electrical principles

Taylor – Hobson Talysurf:

Talysurf is an electronic instrument working on carrier modulating principle. The measuring

head of this instrument consists of a diamond stylus of about 0.002mm tip radius and skid or

shoe which is drawn across the surface by means of a motorized driving unit(gear box), which

provides three motorized speeds giving respectively X20 and X100 horizontal magnification

and a speed suitable for average reading.


FIG: NAME OF THE EACH PART ON THE DISPLAY BOARD


A neutral position in which the pick-up can be traversed manually is also provided. In this case

the arm carrying the stylus forms an armature which pivots about the centre piece of E-shaped

stamping as shown in fig. On two legs of the-shaped stamping there are coils carrying an a.c.

current. These two coils with two other resistances form an oscillator. As the armature is

pivoted about the central leg, any movement of the stylus causes the air gap to vary and thus

the amplitude of the original a.c. current flowing in the coils is modulated. The output of the

bridge thus consists of modulation only as shown in fig. this is further demodulated so that the

current now is directly proportional to the vertical displacement of the stylus only.

The demodulated output is caused to operate a pen recorder to produce a permanent record and

a meter to give a numerical assessment directly. In record of this statement the marking medium

is an electric discharge through a specially treated paper which blackens at the point of stylus

so this has no distortion due to drag and the record strictly rectilinear one.

Analysis of Surface Traces: A numerical assessment is assigned to indicate the degree of

smoothness (roughness) in a number of ways. In practice three roughness measures have shown

themselves to be particularly useful.


1. Ra – Centre Line Average (CLA) or Arithmetic Average (AA):

This is most widely used parameter for specifying surface roughness. It is the arithmetic mean

of the departures Y of the points on the profile from the mean line shown in fig.

The mean line is first determined and the ordinates of the points from the mean line are added

without considering the sign (i.e. irrespective of whether the points are above or below the

mean line)

Where n is the number of ordinates in the sampling length L and Y is the ordinate height.

Ordinates are taken at equal intervals. The CLA can also be calculated from the areas between

the profile and the mean line (shown in fig.)

Where P1, P2, P3…… and Q1, Q2, Q3…… are areas in mm2

L is the sampling length in mm ‘M’is the vertical magnification of the recorded profile.

Talysurf has got built in arrangement from integrating the areas and the average value is

directly given.

2. Roughness Average or Root Mean Square Average Height (RMS) – R q:

It is defined as the average root mean square deviation Y of the profile from its mean length

within the sampling length L.


Where n is the number of ordinates in the sampling length L.

3. Rz – Ten Point Peak to Valley Average Height: Rz

Is the average difference between the five highest peaks and five deepest valleys within the

sampling length, the heights being measured from a line parallel to the mean line and not

crossing the profile (shown in fig.)

PROCEDURE:

The finished component is placed on the surface plate.

Talysurf tester is fixed to the vernier height gauge using adopter at a convenient height.

Make sure that the stylus probe touches the work piece.

Fix the sampling length in the tester.

Then the power button is pressed so that the probe moves on the surface to and fro.

Take the readings of the surface roughness directly from the instrument.

Repeat the above process for the remaining specimen and tabulate the readings

PRECAUTIONS:

•The surface to be tested should be cleaned properly.

•The tester should be fixed to the height gauge properly so that the movement of the probe is

exactly parallel to the surface of work.

•Make sure that the probe gently touches the work


Observations and Tabulation:

S.No

Measurement roughness value

µm

Sample, direction Ra, Rz

Average

Ra

Average

Rz

Grade

1

2

3

4

5

Result:



PROFIILE PROJECTOR

AIM:

To calibrate the profile projector using given samples which dimensions is measured by

micrometre as standard.

CONSTRUCTIONAL DETAILS:

Profile projections are highly sophisticated and versatile designed as per international

standards. This comprehensive range covers all conceivable application its ideal for the rapid

inspection and measurement (linear and angular) of small to medium size components such as

watch parts, tools, rubber components, miniature electronic assemblies and so on.

It’s best quality high resolution optics provides accurate, bright, clear and sharp images. The

special front and back surface mirror are highly polished and lobbied distortion and

reproduction. Three element condenser system and high intensity halogen lamps provides

brilliant images even in day light condition commitment to quality insure that offer the highest

level of precision, quality, reliability and performance.

Two types profile projectors are,

• Vertical floor model, ideal for the rapid inspection

• Horizontal floor model, ideal for the tracing for projected images

PROJECTION CAPACITY:

Projection lens Dial of view field Free working distance

between object and lens

10:1 32mm 23mm

20:1 12.5mm 38mm

FIG: PROFILE PROJECTOR


TABULATION:

Sl.

No

Actual

micrometre

reading in mm

(A)

Profile projector micrometre reading

Error

(A-D)

In

mm

% error

Initial(B)

mm

Final (c)

mm

Difference

b/w B& C (D)

CALCULATION:

% error = (error/actual micrometre reading) x100

FIND THE FLANK ANGLE:

Sl.

No

Initial angle in degree

(A)

Final angle in

degree (B)

Difference b/w

(A&B)

Average

OPERATING PROCEDURE:

1. Switch ON the main. The induction glows, then the instrument is ON.

2. Switch ON the toggle switch. For cooling fan below the light house.


3. Toggle switch 2 for light source ON.

4. Select the capacity of the length for precision operation measured and fix that flow the

projection head.

5. Place the object (balls) on the glass table. TO get the clear image rotate the arm wheel

provided at the right side.

6. After getting the clear image locate the cross wire of the initial point on the image which to

be measured, and then the cross wire moved to the final point. Note down the micro meter

reading. This is done by using micro meter.

7. Now find the difference between initial and final readings.

8. Graph can be plotted between actual micro meter readings Vs. % Error.

RESULT:

Thus the dimension of given samples are measured by using profile projector.


STUDY OF MACHINIG CNC:

1. Machining of simple components on CNC lathe

2. Machining of simple components on CNC Milling

3. Inspection of quality and dimensional practice using Coordinate Measuring Machine