Angle Measurement.pptx
Transcript of Angle Measurement.pptx
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Copyright The McGraw-Hill Companies, Inc.Permission required or reproduction or display.
PowerPoint to accompany
Krar Gill Smid
Technology o Machine Tools!th"dition
#ngular
Measurement
Unit 13
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Objectives
Make angular measurements to an accuracy
of 5' (minutes) of a degree using a universal
bevel protractor
Make angular measurements to less than 5'
of a degree using a sine bar, gage blocks,
and a dial indicator
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Angular Measurement
Important phase of machine shop work
Most common tools
!niversal bevel protractor
"ine bar
"ine plate
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#recision angles
to within 5'
($%$&)
onsist of base
*ernier scale
#rotractor dial
"liding blade
+ial clamp nut
Copyright The McGraw-Hill Companies, Inc. Permission required or reproduction or display.
Universal Bevel
Protractor
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ernier Protractor
!sed to measure obtuse angle ($-.&$)
/cute-angle attachment fastened to
protractor to measure angles less than $ Main scale divided into
two arcs of .&$
"cale divided into .0
spaces on each side of $
If 1ero on vernier scale
coincides with line on
main2 reading in degrees
Copyright The McGraw-Hill Companies, Inc.
Permission required or reproduction or display.
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!eading a ernier Protractor
Copyright The McGraw-Hill Companies, Inc. Permission required or reproduction or display.
3ote number of whole degrees between 1ero onmain scale and 1ero on vernier scale
#roceeding in same direction, note which vernierline coincides with mail scale line
"#$
%ourt& Multiply number by 5' and add to degrees on protractor
dial
' ( ")* +#)
!eading * "#$ +#)
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Sine Bars
!sed when accuracy of angle must be
checked to less than
onsists of steel bar with two cylinders ofe4ual diameter fastened near ends
enters of cylinders eactly $ to edge of bar
+istance between centers usually 5 or .$ in%
Made of stabili1ed tool hardened steel
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Sine Bars
!sed on surface plates and any angle byraising one end of bar with gage blocks
Made 5 in% or in multiples of 5 in%
6apped cylinders with 5 in% 7%$$$0 or .$ in% 7 %$$$05 between centers
8ace accurate to within %$$$$5 in%in 5 inches
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Sine Bars
9ypotenuse of a right-angle triangle :age block buildup forms side opposite
8ace of surface plate forms side ad;acent
anglere4uiredofsine
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,(ample
alculate the gage block buildup re4uired to set
a 5 in% sine bar to an angle of $
anglere4uiredofsine
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Sine Bars
/ngles > ?$@etter to set up work using complement of
angle
/ngle plate turned $ to produce correct angle Ahen sine bar in near-hori1ontal position, small
change in height of buildup will produce smallerchange in angle than near-vertical position
"mall angles
"ometimes impossible to get buildup smallenough to place under one end of sine bar
#lace gage blocks under both rolls of sine bar
3et difference in measurement e4ual to re4uired
buildup
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Sine Bar Used to 3&ec4 /aper
3ecessary to check angle of taper so proper
gage block buildup can be made
In right triangle, /@+2
+ @
/
.0%$$$
.%$$$
%5$$
$0?BBa
$.?B0$B.??%.0
0
.
0
=
===a
Tan
a
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Sine Bar Used to 3&ec4 /aper 5cont26
8rom the solution prior, the following formula
for solving the included angle, when the taper
per foot (tpf) is known is derived%
@y transposition, if the included angle is given,
the tpf may be calculated as follows2
0B