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
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 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
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
Reticules (minutes and Seconds) and Reading of the Ocular
AutoCollimator – eyepiece view
Pentag Prism – Optical Square
Auto Collimator- Squareness testing
Angle Dekkor – Checking right angle
Squareness Tester
Squareness checking – Dial gauge
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
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?