Angle Measurement.pptx

7/24/2019 Angle Measurement.pptx

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PowerPoint to accompany

Krar Gill Smid

Technology o Machine Tools!th"dition

#ngular

Measurement

Unit 13


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13-2

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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13-3

Angular Measurement

Important phase of machine shop work

Most common tools

!niversal bevel protractor

"ine bar

"ine plate


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13-4

#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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13-5

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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13-6

!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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13-7

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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13-8

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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13-9

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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13-10

,(ample

alculate the gage block buildup re4uired to set

a 5 in% sine bar to an angle of $

anglere4uiredofsine


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13-11

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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13-12

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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13-13

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

Angle Measurement.pptx

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