Brunson 771 - Page 36

Model 771, 75, and 76-RH190 Transits 32
Nowlet’sgetbacktoourexample.When
welookedatthefarscalewhenmeasuring
themachineinFigure3.14,wesawtheim‐
ageinFigure3.15.Sincewehavelearned
alittlemoreaboutscales,wecantellthat
theverticalreticlewireisbetweenthe7.8”
and7.9”targetgaps.Nowwe’llusethe
opticalmicrometerasaverniertogetthe
exactscalereading.Weturnthegradu‐
ateddrumonthemicrometersothatthe
reticlemovestotheleft,andweplacethe
verticalwireexactlyonthe7.8”targetgap
(Figure3.20).Thenwereadthegraduated
drum,anditindicatesthatwehavemoved
0.085”.Sincetheunalteredlineofsight
(withthemicrometersetat0.0)wasmore
than7.8butlessthan7.9,weknowthatthe
finalreadingis:
7.8”+0.085”=7.885”
Sothedistanceofthemachinecomponent
fromthereferencelineofsightwas7.885”.
Nowlet’ssaythatwetakeareadingfromthenearscaleinthesame
manner,andwegetafigureof9.734”.Wethenknowthatthema‐
chineisoutofparallelwiththereferencelineby:
9.734”‐7.885”=1.849”
overthedistancebetweenthetwoscales.



Figure3.18
Figure3.19