ANGLE MEASUREMENTS

B.Ramamoorthy

Manufacturing Engg. Section

IIT,Madras 600036

ANGLE MEASUREMENTS

Sine bar

Autocollimator

Electronic Level

Profile Projector

Laser Interferometer

CMM etc

Tool maker’s microscope

Angle Gauges Spirit level

Protractors

Clinometer

Beam comparator

Angle Gauges

Available in sets

1, 3, 9, 27, 41- degrees

1, 3, 9, 27 - minutes

3, 9, 27 or 6, 12, 18 – seconds

plus a square block 13 gauges in Set 1

1, 3, 5, 15, 30, 45 - degrees

1, 3, 5, 20, 30 - minutes

1, 3, 5, 20, 30 - seconds plus a square block 17 gauges in Set 2

Slip Gauge Set

Wringing of Slip gauges

Clinging power of Slip Gauges

89

89

3.2

16

Typical size and shape of an angle Gauge

Addition & subtraction

Sine Bar

Specified using centre distance 100, 200, 400 mm etc. 4”, 5”,10” etc.

5” sine bar with error of

Centre distance 0.001mm

450 2.8”

600 4.0”

700 6.0”

Sine Bar Centre

Gage

Block

Sine Bars - Block Type

Spirit level

To measure the angular divergencies

Simple and yet powerful

Sensitivity is defined as the

Displacement of bubble / Change in inclination in mm / sec

R = L / θ = 2. 5 mm / 10 secs

= 50 m app.

Spirit Level – Principle, (R = t / )

Sensitivity =Displacement Per scale division of bubble for a Change in

inclination ( mm / sec ) R = L / θ = 2. 5 mm / 10 secs = 50 m app.

θ

L

R

Block Levels

Principle of Auto Collimation

Setting up of Angle gauges for measurement using Angle Dekkor

Angle Dekkor – and Eyepiece view

Angle Dekkor – Eyepiece view

Optical diagram of a Micro optic Auto collimator

1 eyepiece

2,4 prisms

3 beamsplitter

5 crosswire

6 lamp

7,8 reflectors

9 objective

lens

10 plane of setting images

Minute’s scale knobSecond’s scale knob

1 optical flat

2 minute’s scale knob

3 Ocular

4 minute scale

5 Second’s scale

6 Cam

7 Pinion

8 Knob for tilting flat

9 Gear wheel

10 Pin

Measuring Ocular and its reticules

Optical Flat

Reticules (minutes and Seconds) and Reading of the Ocular

θ

AutoCollimator – eyepiece view

Pentag Prism – Optical Square

Prisms..

Polygons

Angle Gauges

Slip Gauge Set

Auto Collimator- Squareness testing

Angle Dekkor – Checking right angle

Squareness Tester

Squareness checking – Dial gauge

Circular Table

Auto collimator-Calibration of a circular Table with a polygon

AC

Square Block

Circular Table

A typical 3D profile of a Surface Plate

Straightness Checking – AutoCollimator and reflector

Straightness Checking – AutoCollimator and reflector, Readings

Cumulative Error – Graph, autocollimator

Cumulative and Actual Error Graphs – Autocollimator

Testing a machine tool and readings ,straightness plot

5 ”

4 ”

Straightness Evaluation – Autocollimator readings

Readings – 10 ’ 00 ’,10 ’10 ’’,9 ’55” ,10 ’15”,9 ’56”

Pitch distance – 100mm

10”

15”

5

108.0

10”

15”1.6

2.5

4.8

End points Zero Method

2.3

3.6

5.0

0

Straightness error = 3.6 +2.3µm

End Points Zero Line

10”

15”

Error = 5.0 µm

Crest points Method

Crest points line

5.0

10.012.5

7.5

2.50.0

10” = 5 µm

Error = 6.25µm

Valley points method

Valley points line -1

Valley points line -2

2.53.75

5.0

5.0

10.0

7.5

Error = 5.0 µm

Valley points line10”

15”

Crest points line

End points zero line

Straightness Evaluation - Methods

Profile Projector

Light rays from Lamp

Glass Table

Lens

Reflecting Mirror

Glass Screen

Profile Projector/Shadow Graph

Tool maker’s Microscope

Lamp

To Eye Piece

Lens

Tool Maker’s MicroscopeReflector

Glass Table

m1

d/2 Sec Ө / 2 Ө/2

Diameter “ d ”

Ө/2

D1

Talyvel with a stride base (to set horizontal lines)

Two halves

Of the inductive

transducer

Centre zero meter

Pendulum Device

Incorporating armature

Knobs for Zero Adjustment

Talyvel with Meter unit (battery operated)

Talyvel with Block base

Flatness better than +/- .0025mm, to facilitate straightness check etc.

Rochdale’s Beam Comparator

Surface plate

Dial gauge

Beam comparator

Rochdale - Beam Comparator

Clinometer

Straightness Testing – Wedge Method

Flatness checking using Straight edge

Flatness Evaluation

Reading Assignments

1)Manufacture of surface Plates – reason?

2) Large radius Grinding – Spirit Level

3) Parallelism of Micrometer faces – how to check using AC?