Brunson 771 Guide

Models 771, 75, & 76-RH
Optical Tooling Transits
Instrument
Company
Operation and
Field Adjustment Manual

Helping the World Measure
Since 1927
www.brunson.us
Copyright 2009-2011 Brunson Instrument Company
Kansas City, Missouri
8000 E. 23rd Street
Kansas City, MO 64129
Tel: [phone]
Fax: [phone]

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TableofContents

Thankyoufor
purchasing
aBrunsonTransit.
Rememberthatour
customersupportdoes
notstopaftershipmentof
aproduct—wearehereto
helpyouwithany
measurementchallenges
thatyoumayhave.
Chapter1:Introduction1
WhatisaTransit?1
WhatDoesaTransitDo?3
TheThreeDifferentTransits4
Chapter2:GettingStartedWithYourTransit7
HandleYourTransitWithCare7
RemovingFromtheCase8
UsingtheShiftingCenter8
RoughLeveling8
PreciseLeveling9
TheReticle11
HowtoProperlyFocus11
FindingInfinityFocus11
PointingtheTelescope12
InstallingLightingAccessories12
Chapter3:MeasuringTechniques15
BuckingIn15
Autoreflection17
Autocollimation19
Collimation23
Collineation26
ReticleProjection27
MeasuringWithMicrometers28
Chapter4:FieldCalibrationChecks35
Plate(“Bull’sEye”)Vial37
MicrometerChecks38
“DoubleCenter”Check40
HorizontalAxisRunout41
VerticalSpindleRunout42
HorizontalCentering43
HorizontalCollimation44
PlumbLineCheck46
Cross‐AxisTelescopeCollimation49
PegTest51

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1Operation and Adjustment Manual
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Inthischapterwewilladdressthefollowingtopics:

 Whatisatransit?
 Whatarethecomponents?
 Whatdoesatransitdo?
 ThedifferencebetweenthethreeBrunsontransits
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Themostimportantthingaboutatransitisthatithasatelescopeon
agimballingmechanism,soitcanrotatebackandforthhorizon‐
tally(azimuthdirection),butitcanalsorotateupanddown
(elevationdirection).

Almosteveryoneisfamiliarwithasurveyor’stransit.However,it
isworthexplainingthegeneraldifferencebetweenourtransitsand
thoseusedbysurveyors.OpticalToolingtransitshaveanumberof
modificationstomakethemdeadlyaccuratewhenshootingover
distanceswhich,toasurveyor,wouldseemshort(lessthanacou‐
pleofhundredfeet).Inaddition,wedonotneedtotakereadings
intwotelescopepositions(directandreverse)inordertoachieve
thisaccuracy.Thisispossiblebecauseourtransitshaveseveral
specialcharacteristics:

a)Theyhaveanextremelystraightlineofsight.Asyoufocusthe
telescopefromneartofar,thelineofsighttravelsinanextremely
straightline.Thatis,pictureputtinganimaginary,
weightless,tautstringdownthecenterofthetelescope,
stretchingstraightoutacoupleofhundredfeet—the
stringwouldalwaysbeinthecenterofthecrosshairsas
youfocusfromneartofarandbackagain.

b)Atransit’sthreemajoraxesareallmutuallyorthogonal
(allatrightanglestoeachother).Therearetworota‐
tionalaxesonyourtransit,andoneaxiswhichdoesnot
rotate(seeFigure1.2).Thefirstrotationalaxisisthever‐
ticalaxis.Thespindleandbearingswhichcreatethever‐
ticalaxisarehousedinthetransit’sbase.Theentireup‐
perportionofthetransit(standardsandtelescope)rotate
horizontallyaroundthisaxis.Thesecondrotationalaxis
isthecross‐axis.Thisisthehorizontalaxisaroundwhich
thetelescoperotates.Thethirdaxisisthelineofsight.

c)Lastly,allthreeofthemajoraxesmeetatoneprecise
point.Justbecausetheaxesareallmutuallyorthogonal
PleaserefertoFigure1.1
forageneralorientationto
componentterminology.
Chapter1‐Introduction
Note:Thismanualappliestothe
followingBrunsonproducts:

 771and771‐HJigTransits
 75and75‐HOpticalTransit
Squares
 76‐RH,76‐RH190,and76‐
RH190MTelescopicTransit
Squares

Atthistime,themodels771,771‐H,
75,and75‐Harenolongerpro‐
ducedbythefactory.However,we
haveincludedtheminthismanual
duetotheirpastpopularityandthe
factthatmanyoftheseinstruments
remaininthehandsofalignment
technicianswhomayfindthisinfor‐
mationuseful.
Whatisatransit?

Model 771, 75, and 76-RH190 Transits2
1.Levelingscrews(4)
2.“Spider”base
3.Platevial
4.Telescope(eyepieceend)
5.Cross‐axistelescopeeyepiece
6.Focusknob
7.Telescope(objectiveend)
8.190‐xOpticalMicrometer
9.Cross‐axistelescopeobjectivelens
10.Verticaltangentclamplock
11.Coincidencelevel
12.Cross‐axistelescopelightingadapter
13.Standards
14.Horizontaltangentclamplock
15.Baseplate
16.Horizontaltangentadjustmentscrew
17.Plate
18.Verticaltangentadjustmentscrew
19.Shiftingcenter
Figure1.1
OrientationtoComponents

3Operation and Adjustment Manual
doesn’tnecessarilymeanthatthelineswouldallintersectatthe
sameexactpointinspace.However,onourtransits,theselinesdo
intersect.Thisisanimportantcharacteristicwhenaccuracyispara‐
mount,particularlyatshorterdistances.Ofcourse,youcan’tsee
thisintersectionpoint–itisburiedinthemiddleofthetelescope.

Thesearethethreedistinctcharacteristicsthatourtelescopeshave
whichallowthemtomakeveryprecisemeasurementsoverrela‐
tivelyshortworkingdistances.However,thereisonemorevery
distinctivecharacteristicwhichseparatesOpticalToolingtransits
fromallothers–theopticalcross‐axis.Our76‐RH190hasaninfin‐
ity‐focusedtelescope,completewithasecondeyepieceandsecond
setofcrosswires,housedinthecrossaxis.Thiscross‐axistelescope
isusedinanumberofoperationstosetthemaintelescopeperpen‐
diculartoanothertelescopeoramirror(whichmaybemountedon
arotatingshaftorotherreferenceplane).





Atransitisaveryflexiblemeasuringtool.Itcanestablishvertical
orhorizontalopticalplaneswhichareextremelyflat.Itcanestab‐
lishopticallineswhichareextremelystraight,extendinginanydi‐
rection.Oncetheseplanesandlinesareestab‐
lished,youcanusethemasreferencesfrom
whichtomeasureotherpointsofinterest.You
candeterminewhethermachinecomponents
areparallel,flat,level,square,orstraight.This
meansyoucanevaluatethegeometricrela‐
tionshipsrelatedtothealignmentofalmost
anypart,structuralcomponent,machine,tool,
surface,substrate,wall–orjustaboutany‐
thingelse.Averyfewexamplesofthiswould
be:

 Alignmentofbearingsandbearing
journals.
 Rollparallelisminpaperandmetals
mills,orprintingpresses
 Machinetoolevaluation:bedlevel‐
ing,bedflatness,geometricintegrity
ofspindlesandothercomponents
 Layoutformachining
 Crankcasealignment
 Straightnessofenginebores,turbine
cases,torpedotubes,lineshafts,etc.
 Checkrelationshipsofrightangle
planes

TheOpticalToolinginstrumentsareextremely
flexible.Youcanusethemtomakejustabout
anymeasurementorgeometricevaluationthat
Figure1.2
Sowhatdoesatransitdo?

Model 771, 75, and 76-RH190 Transits4
youcandesigninyourmind.

Asweindicatedearlier,the76‐RH190istheonlycurrentlypro‐
ducedOpticalToolingtransit.Althoughthismanualwaswritten
specificallyforthe76‐RH190,muchoftheinformationitcontainsis
applicabletotheothertransitsaswell.





Thedifferencesbetweenthe771‐x,75‐x,and76‐xtransitsrelate
solelytothewayinwhichthecross‐axisisconstructedandused.
Alltransitssharethesamebase,standardassembly,bearings,and
telescopeoptics.Onalltransits,thetelescoperotatesinavertical
planearoundahorizontalaxis(the“cross‐axis”).Thecross‐axisis
perpendiculartothelineofsight.

Themostbasictransitisthe771or
771‐H.Thesetransitshavenoop‐
ticsinthecrossaxis.Theyare
usedas“jig”transitstoestablish
straightlinesandplanes.How‐
ever,theyhavenocapabilityto
makeanaccuraterightangleturn.

Onestep“up”isthemodel75or
75‐H(ontheleftinFigure1.3).
Thesetransitshaveacrossaxis
whichishollowandcanbeseen
through.Ononesideofthecross‐
axisisaclearglasswindow,and
ontheothersideisapartiallyre‐
flectivemirror.The75(‐H)does
everythingthatthe771(‐H)can
do,butcanalsobeusedincon‐
junctionwithanotherinstrument
toproduceaveryaccurateright
angle.

Themostflexibletransit(andthe
onlyonecurrentlyproduced)is
themodel76‐RH190.Thecross‐
axisofthistransitcontainsatele‐
scopethatispermanentlyfocusedatinfinityandisequippedwith
reticlelighting.Arightangleeyepieceisprovidedasstandard
equipmentonthecross‐axistelescope.The76‐RH190maybeused
toestablishstraightlines,horizontalorverticalplanes,andcreate
accuraterightangleswithrespecttoothertransits,alignmenttele‐
scopes,mirrors,orotherphysicaltargets.Whenthecrosswiresof
thetransit’scross‐axistelescopearesetonthoseofareferencetele‐
scopeormirror,themaintelescopeofthetransitwillsweepaplane
atpreciserightanglestothecross‐axisreferenceline.
The75‐Htransit
(above,left)hasbeendis‐
continuedbutmanyare
stillinuse,andmostof
theinformationcon‐
tainedinthismanual
stillapplies.
Figure1.3
Thethreedifferenttransits

5Operation and Adjustment Manual

The“‐H”inthevariousmodelnumbersreferstoa“Hollow”verti‐
calaxis.Transitsthathavethe‐Hdesignationallowyoutolook
straightdownthroughahollowverticalspindleandtoseetargets
orcollimatorswhicharedirectlybelowthebaseoftheinstrument.
Whydoweusefour“feet”(levelingscrews)insteadofthree?

Weareoftenaskedthisquestion,sincemosttheodoliteshavethreeleveling
screws.Thereasonisthatwhenadjustingfourlevelingscrews,theinstrument
heightisnotaffected.

Whenthreelevelingscrewsareused,twoof
themmustnecessarilyformapivotaxis,and
thethirdisusedtoraiseorloweronesidetotilt
theinstrument.Itgivestheeffectshownatleft.
Thereddotindicatestherelativeinstrument
heightbetweentwopositionsoftheinstrument
(tiltedandnottilted).


However,whenfourlevelingscrewsareused,
theinstrumentposition(again,reddot),effec‐
tively,doesnotchange.Thisgivestheeffect
shownatright.Onesidegoesupbythesame
amountastheothersidegoesdown,andthe
instrumentpivotsatitscenter,notononeside
ortheother.

Thisisjustanotherexampleofthewaythatwehavecraftedourinstrumentsto
bemoreaccurateatshorterranges.Overlongerdistances,minorchangesinin‐
strumentheightarenotimportant.Butwhenmeasuringveryaccuratelyover
shorterdistances,avoidingchangesininstrumentheightcanbecomecrucial.

Model 771, 75, and 76-RH190 Transits6

7Operation and Adjustment Manual


Inthischapter,wewilldiscuss





Notethattheseproductsareprecisioninstrumentsandshouldal‐
waysbehandledwithcare.

 Donotforceanyofthescrews.Afirm(butnottight)ten‐
siongivesthebestresults.
 Keepyourinstrumentcleananddry.Protectitfromthe
weatherifusedoutdoors.
 Allowyourinstrumentto“soak”foratleast4hoursin
thetemperatureinwhichitwillbeused,sothatshifts
duetothermalchangesareminimized.Ifyouaremov‐
ingthetransitacrossthermaldifferentialsofmorethan
20°F,allowittosoakfor8hours.Theinstrumentshould
beoutofthecaseduringthistimeforbetteraircircula‐
tion.
 Whentakingasighting,or
readingoneoftheseinstru‐
ments,removeyourhands,
andmakesureanyother
pressureisalsoremoved.
Keepyourinstrumentcalibrated.
Maketherecommendedfieldchecks
(seeChapter4)aswellasperforminga
completecalibrationatleastannually.

Notethatthereisawarningprintedon
thesideofyourtransitwhichsays
“Caution—DoNotPlungeTelescope
FromFlange”.Plungingthetelescope
meanstorotateitintheverticalplane,
asyoumightwhenyouwanttolook
furtherupordown.Specifically,
plungingreferstoreversingthedirec‐
tionofthetelescopebyrotatingit180°
Chapter2‐GettingStartedwithYourTransit
 Howtohandleyourtransit
 Removingitfromthecase
 Usingtheshiftingcenter
 Roughleveling
 Preciseleveling
 TheReticle
 Focusingtheeyepieceand
telescope
 FindingInfinityfocus
 Pointingthetelescope
 Installinglightingaccesso‐
ries
Figure2.1
Handleyourtransitwithcare

Model 771, 75, and 76-RH190 Transits8
intheverticalplane.The“flange”isthecomponentuponwhichthe
warningisprinted.Thissimplymeansnottorotatethetelescope
bygrabbingtheflangeandtwistingit.Torotatethetelescopeprop‐
erly,putyourhandonthetelescopebarrelitself.





Loosenboththehorizontalandverticaltangentclampscrews.
Graspthestandardsfirmlywithonehand,andthebasewiththe
otherhand.Liftgentlyfromcaseandplaceonastandorothersup‐
port.Whilemaintainingaholdonthestandardswithonehand,
rotatethebasesothatthebottomplateisfirmlythreadedontoany
3½”–8externalthreadedmountorstand.Whenreplacingthe
transitintothecase,slightlytightenthehorizontalandverticaltan‐
gentclamplockscrews—butonlydosogently.

Aspecialcenteringmount,differentthanmostofourinstrument
adapters,maybeemployedtophysicallyplacethehorizontalcen‐
terofthetransitinaknownlocation.Theshiftingcenterofthe
transitextendsaboveandbelowthebaseplate(visiblebetweenthe
levelingscrewsandalsofrombelowasa2”diameterringcentered
onthebottomofthebaseplate).Thisshiftingcenter(radius=1±
0.0001”)fitsintospecialmountshavinganaccuratelyboredinner
diameter.Ifthetransitistobelocatedononeofthesemounting
rings,thelevelingscrewsshouldbeloosenedslightlysothebase
platecanmovearoundinrelationtotheshiftingcenter.Re‐tighten
thelevelingscrewsonlyafterbaseplateistightenedonthemount.





Oncemountedonastandorotherstableinstrumentmount,thefol‐
lowingprocesswill“rough‐level”thetransit,meaningthatthetran‐
sitwillbebroughtroughlytoplumb,andbewithinrangeofthe
precisionlevelvialmountedalongthetelescopeaxis.

Toroughlevel,loosenanytwoadjacentlevelingscrewsandturn
thefourarmʺspiderʺbasesothattwodiagonallyopposedleveling
screwsareinlinewiththeprincipalsightingdirectionthatwillbe
used.Figure2.2illustratesthis,withthespiderbaselinedup
“square”withthetelescopeandcrossaxis.Re‐tightentheleveling
screws.

Acircular“bull’seye”vialrestsonthehorizontal“plate”abovethe
basebutbelowthetelescopeaxis(Figure2.3).Wecallthisthe
“platevial”.Centerthisbubbleinthefollowingmanner:Puta
Removingfromthecase
Usingtheshiftingcenter
Roughleveling

9Operation and Adjustment Manual
thumbandforefingeroneachoftwodiagonallyopposedleveling
screws.Tomovethebubble,turnthelevelingscrewsatthesame
time,andinoppositedirections(thumbsmovingtogetheror
thumbsmovingapart).Thebubblewillmoveinthedirectionof
movementofyourleftthumb.Movethebubblesothatitisinthe
middleoftheplatevial,andatleastinlinewiththeinscribedcircle
(itprobablywon’tbeexactlycentered).Nowmoveyourhandsto
theothersetoflevelingscrews.Usingthesameprocess,movethe
bubbledirectlyundertheinscribedcircleinthecenteroftheplate
vial.Youmayhavetorepeatthisentireprocessacoupleoftimesto
getthebubblecentered.Keepalightbutfirmtensiononthescrews
allthetime.Neverputheavytensiononlevelingscrews.

Nowrotatethetransit180°aboutitsverticalspindle.Thebubble
shouldstaycenteredundertheinscribedcircle.Ifitdoesn’t,the
vialisoutofadjustment(refertoChapter4ofthismanualforthe
calibrationproceduretocorrectthis).





Topreciselylevel(sometimescalled“precisionplumb”)thetransit
usingthecoincidencevial,rotatethestandardsofthetransituntil
thetelescopeisinlinewithonepairofdiagonallyopposedleveling
screws.Plunge(rotate)thetelescopesothatthecoincidencevialis
ontopofthetelescope,andlevelthetelescopebyeye(Figure2.4).
Toassistyou,lookatthesideofthecoincidencevialandposition
thebubbleroughlyinthecenterofitstravel.Gentlytightenthe
Figure2.2
Figure2.3
Preciseleveling

Model 771, 75, and 76-RH190 Transits10
verticaltangentlock.

Thebubbleinthecoincidencevialop‐
erateslikeanyotherlevelvial,butthe
operatorviewsa“foldedimage”of
bothendsofthebubblesimultane‐
ously.Ifthetelescopeistilted,thetwo
bubbleimagesmoveinoppositedirec‐
tions.However,whenbothendsof
thebubblearebrought“intocoinci‐
dence”(Figure2.5),thevialisdead
level.Youwillseesomethingsimilar
toFigure2.5bylookingintothevial’s
turret.Sincethehumaneyeisex‐
tremelyskillfulatdetectingeventiny
breaksinotherwisecontinuouslines,
thissystemmakesreadingthelevelextremelysensitiveandaccu‐
rate.

Rotatetheturretonthecoincidencevialsothatyoucanconven‐
ientlyviewthesplitimageofthebubbleinside.Areflectorhaving
onewhitesideandonemirroredsideisprovidedtohelpilluminate
theimage.Positionthereflectorforoptimalbubbleillumination.

1.Usingtheverticaltangentadjustmentscrew,bringthe
splitimageofthebubbleintocoincidence(Figure2.5).

2.Rotatethestandards180°sothatthetelescopeisnow
pointingintheoppositedirection.Ifthebubbleisoff
center,removeone‐halftheerrorwiththetwoleveling
screwswhicharelocateddirectlyunderthetelescope.
Removetheotherhalfoftheerrorusingtheverticaltan‐
gentscrew.Rememberthatyoucanseethebubbleby
lookingintothesideofthevialitselfratherthanintothe
turretwindow—thismayhelpyoudeterminewhichway
thebubblemustmove.

3.Nowrotatethestandards90°sothatthetelescopeislo‐
cateddirectlyovertheotherpairoflevelingscrews.
Bringthebubbletocenter,usingonlythetwoleveling
screwsunderthetelescope.

4.Fromthisposition,rotatethestandards180°.Again,if
thebubbleisoffcenter,removeone‐halftheerrorwith
theverticaltangentscrew,andtheremainingone‐half
errorwiththetwolevelingscrewswhicharelocatedun‐
derthetelescope.

5.Repeatsteps2‐4,alternatingovereachpairofleveling
screws,untilthebubbleremainsincoincidenceinallfour
“compasspoint”positions.


Figure2.4
Notethatthetransit’sverti‐
calspindlemaybebrought
intoplumb(exactlyvertical)
evenifthecoincidencevial
itselfisnotcalibratedprop‐
erlywithrespecttothetele‐
scopebarrel.
Figure2.5

11Operation and Adjustment Manual



ThetelescopeofeachOpticalToolinginstrumentcontainsareticle–
orcrosshair–whichdefinesthecenterofthelineofsight.When
youlookintoatelescope,youseethereticleʺsuperimposedʺupon
theimageofwhateveryouhavethe
telescopefocusedon.Thereticleis
splitintofourquadrants;twohavea
singleʺwireʺ(filar),theothertwohave
adoubleʺwireʺ(bi‐filar).Thiscon‐
figurationwasoriginallyadoptedbe‐
causethehumaneyeisextremely
goodatdetectingtinydifferencesin
alignmentbetweencloselyspacedob‐
jects.Therefore,thispatternmakesit
mucheasiertovisuallyalignthereti‐
clewithotherimages(ex.,opticaltar‐
gets,scales,andreticleimagesre‐
flectedfrommirrors).


Focusingsoundseasy,butit’ssurprisinghowmanypeopledon’t
understandtheeffectsofsomethingcalledparallax.Here’showto
properlyfocusyourinstrument.First,pointthetelescopeatasheet
ofwhitepaperorotherlightcoloredbackground.Don’tworry
aboutfocusingthetelescopeusingthefocusknob,theimagecan
remainblurry.Instead,usetheknurledringontheeyepiecetofo‐
custhereticlesothatitissharpandblack.

Nowpointthetelescopeatatargetofinterestandfocustheimage
usingthefocusknobonthetelescope.Slightlyshiftyourheadleft
andrightwhilelookingatthereticleasitis“superimposed”over
theimageofthetarget.Ifthereticleappearstofloatslightlytothe
leftandrightoverthetarget,parallaxispresentinthesystem.This
occurswheneitherthetelescope’smainopticalsystemortheocular
(eyepiece)system,orboth,arenotfocusedpreciselyontheplaneof
thereticle.Parallaxcanleadtoerroneousmeasurementsifnotre‐
moved.Toremovetheparallax,repeatthetwostepsagain,being
carefultoachievecriticalfocusineachstep.



Therearemanyoccasionswhenitwillbeimportanttoputyour
telescopeatinfinityfocus(e.g.,autocollimatingyourtelescopeona
mirror).Infinityisimportantbecause,fromanopticalstandpoint,
lightrayscomingfroman“infinitedistance”areallparalleltoeach
TheReticle(crosshairs)
Howtoproperlyfocus
Thefilar/bi‐filarreticle
imageasseenwhen
lookingintothetele‐
scope.
Figure2.6
Findinginfinityfocus

Model 771, 75, and 76-RH190 Transits12
other,orcollimated.
Thefocusknobonthetelescopehasan
indicatorofthedirectionyoumustturn
ittofindinfinityfocus,butyoucan’t
justturnitallthewayinthatdirection
andexpecttothetelescopetobefo‐
cusedatinfinity.
Theeasiestwaytofindtrue“infinity
focus”istoholdanopticallyflatmirror
(suchasourmodel185)rightup
againsttheobjectiveendofthetele‐
scope.Turnonthetransit’sinternalillumination(see“Installing
lightingaccessories”below).Turnthefocusknoballthewayinthe
directionofinfinity(indicatedontopofthefocusknob).Then,turn
theknobslowlyintheoppositedirection,andwatchcloselyforthe
reflectedimageofthereticle.Itcangobyprettyquickly,sogoing
slowlyisimportantwhilelookingthroughthetelescope.Onceyou
havefocusedthetelescopesothatyoucanclearlyseethereflected
reticleimage,youknowthatthetelescopeis,bydefinition,focused
atinfinity.



Releaseboththehorizontalandverticaltangentclamplocks,and
movetheinstrumentbyhand.Precisepointingisaccomplishedby
re‐lockingbothclampswhenyougetclosetothetarget,andthen
turningthetangentadjustmentscrewsforpreciseplacementofthe
reticle.Bothtangentadjustmentscrewsareoutfittedwithwobble
pinswhichallowforsmoothtranslationoftheaxes.Thefinalset‐
tingshouldbemadebyturningthetangentscrewinaclockwise,or
pushing,direction.Thiswilleliminateanypotentialsubsequent
movementduetofrictionofthespring‐loadedplungerswhichop‐
posethetangentadjustmentscrews.



Forcertainproceduresthatwewilldiscussinthismanual,(e.g.,col‐
limation,autocollimation,andreticleprojection)itisnecessaryto
illuminatethereticleofyourtransitfromtheinside.Amodel76‐x
transithastworeticles(oneinthemaintelescopeandoneinthe
cross‐axistelescope)whichmayneedtobeilluminated,depending
uponwhatyouaredoing.

Illuminatingthecross‐axistelescopereticle.Yourtransitcomes
equippedwithalightsourceforthecross‐axistelescope(model76‐
Thereflectedimageofa
reticle(here,located
aboveandtotherightof
center)willappearonly
atinfinityfocus.
Figure2.7
Installinglightingaccessories
Pointingthetelescope

13Operation and Adjustment Manual
xonly).ThisLEDlightsourcefitsintothereceptacle(red
arrowinFigure2.8).Thesupplytransformerworkswith
either110Vor220Vsources.Installationorremovalofthe
lightsourceissimpleandquick.Simplyinstallthetwo‐
wayadapteronthecross‐axislightingreceptacle,andpush
theLEDlamphousinginuntilitclicksintoplace.Thelight
sourcehasanin‐lineswitchforeasycontrolofthelight.

Rememberthatthefocusofthecross‐axistelescopeisper‐
manentlyfixedatinfinity.Thistelescopeismeanttobe
usedasacollimatororautocollimator.Wewilldiscussthis
more,lateroninthemanual.


Illuminatingthemaintelescopereticle.Whenyouwishto
usethemaintelescopeforcollimation,autocollimation,orreticle
projection,youmustinstallamodel196‐1combinationeyepiece
unit.Todothis,removetheshortsectionofthemaintelescopebar‐
rellocatedjustinfrontoftheeyepiece(SeeFigure2.9),andreplace
itwiththe196‐1eyepieceadapter.Notethatthe196‐1hasa
knurledlockringwhichallowsyoutotightentheadapterinany
givenorientationonthetelescopebarrel.

Beforeinstallingthiseyepiece
adapteronthetelescope,make
suretheknurledlockring(red
arrowinFigure2.10)issecured
againsttheadapter.Itshouldbe
“bottomedout”onthethreads
ratherthanlooseonthethreads
orneartheopenendofthe
adapter.Thenthreadthe
adapterintothemaintelescope
barrelasfarasyoucan.Next,
backofftheadaptertothede‐
siredradialorientation(lamp
receiverpointinguporpointing
down)andlockitinplaceby
turningtheknurledlockring
towardthefrontofthetele‐
scope.

Next,removetheeyepieceassemblythatisstillcon‐
nectedtotheshortsectionofthetelescopebarrelwhich
wasremoved,andinstallitonthe196‐1eyepiece
adapter.

Toinstallthelight,removethecapfromthelampre‐
ceiver(undertherightthumbinFigure2.10).Thenin‐
stallthetwo‐wayadapterbythreadingitsknurledring
ontothelampreceiver.PlugintheLEDlightsource
untilitclicksintheadapter.

Figure2.8
Figure2.9
Note:Toinstallarightangleview‐
ingeyepieceonthemaintelescope
(convenientforveryhighangle
shots),youmaywishtoinstalla193
‐Lratherthanthe196‐1.Theseac‐
cessoriesareinstalledinbasically
thesameway,byfirstremovingthe
shorttubesectioninfrontofthe
eyepiece.

Model 771, 75, and 76-RH190 Transits14
Laterinthismanual,wewill
discusssomeoftheoptical
toolingtechniqueswhichre‐
quirebacklightingofthereti‐
cleusingoneoftheseadapt‐
ers.
Figure2.10

15Operation and Adjustment Manual


Therearemanyjobsthatyoucandowithyourtransit,whichmay
bepurchasedwitha190‐typemicrometerinastandardconfigura‐
tion.Youcanevaluateanumberofalignment‐relatedcharacteris‐
ticsofmachineryorotherstructures,suchasstraightness,plumb,
level,flatness,andothers.However,toperformcertainOptical
Toolingprocedures,otheraccessoriesarerequired.Wewillmen‐
tionsomeoftheseaccessoriesaswediscusstherelatedtopics.

Inthischapterwewilldiscussthefollowingtopics:

ThisdiscussionismeanttomakeyouawareofsomeoftheOptical
Toolingproceduresthatyoucanuseinalignmentandmeasure‐
mentwork.Thismanualisnotagoodsubstituteforourtraining
classes,inwhichweofferhands‐ontrainingoftheseandmany
otherOpticalToolingtechniques.

We’llexplainwhatthesetermsmean,andhowtoaccomplishthem
usingyourtransit.



Inmanyalignmentjobs,itisnecessarytoputthelineofsightof
yourtransitdirectlyonalinecreatedbytwoknownreferencetar‐
gets.Forexample,inFigure3.1(showingaviewfromoverhead),
sometargetshavebeeninstalledinthefloor.Thesetargetsrepre‐
sentalinewhichisparalleltothecenterlineofamachineonwhich
youneedtoaligncomponents.Inpreparationfordoingthisalign‐
mentjob,itcouldbenecessarytobringtheinstrumentinlinewith
thesetwofloormonuments.

NoteinFigure3.1,thetransitmustnotonlyberotatedsothatitis
paralleltothelinedefinedbythetargets,butitmustalsobeshifted
sideways.“Buckingin”isarepetitiveprocessinwhichyouadjust
boththeinstrument’sangleaswellasitslateralpositionsothatthe
transitisplaceddirectlyinlinewithtwotargets.Ortobemoreac‐
curate,sothatthetransit’sverticalspindleliesintheverticalplane
whichalsorunsthroughthecenterofthefloortargets.

Notethatangularadjustmentsareeasyenoughtomakeusingthe
horizontaltangentadjustmentscrewonthetransititself.However,
Chapter3‐MeasuringTechniques
 “Buckingin”
 Autoreflection
 Autocollimation
 Collimation
 Collineation
 Reticleprojection
 Measuringwithmicrometers
“Buckingin”

Model 771, 75, and 76-RH190 Transits16
Alwayssetthetelescopeon
thefartargetbymak‐
ingangularmoves
usingthehorizontal
andverticaltangent
screw(s).

Alwayssetthetelescopeon
theneartargetby
makinglateralmoves
usingalateralslideor
precisionlift.
lateralshiftsoftheentireinstrumentarenotaseasy.Togreatly
simplifythis,werecommendtheuseofalateralslidemountedbe‐
tweenthetransitandthestandonwhichitismounted.

Stepstobuckthetransitintothetargetline:

1.Roughlypositionthetransit.Setuptheinstrument
standnominallyinlinewiththetwotargets.

2.Roughlevel.Roughlevelthetransitasdescribedin
Chapter2“RoughLeveling”.

3.Preciselevel.Formanyapplications,preciseleveling
yourtransitisrequiredpriortobuck‐in(coveredin
Chapter2).Technicallyisitpossibletobuckintotargets
withoutpreciseleveling,butthetransitwillnotendupin
theverticalplanedefinedbythosetargetsunlessthetran‐
sititselfispreciselyplumb.Afulldiscussionof
thisfactisbeyondthescopeofthismanual,butis
coveredinmoredetailinourOpticalTooling
classes.

4.Settofartarget.Focusthetelescopeonthefar
targetandsetthecrosswiresdirectlyoverthattar‐
getusingthehorizontaland/orverticaltangent
adjustmentscrews.Ifthetransitisbetweenthe
targets(asinFigure3.2),simplyassignoneofthe
targetstobethe“fartarget”,andsetonit.

5.Settoneartarget.Withoutmovingthehori‐
zontaltangentscreworturningthestandardsof
thetransit,turnthetelescopedownwardandfocus
onthesecondtarget.Notethatifthetransitislo‐
catedbetweenthetargets(asinFigure3.2),youwill
havetoturnthetelescope“through”thestandards
topointintheoppositedirection.Regardlessof
whetheryouareinasituationlikeFigure3.1or
Figure3.2,thissecondtargetwillinvariablybeoff
toonesideofthefieldofviewunlessyouarein‐
crediblylucky.Forpurposesofillustration,let’s
saythattheobservedlateraldistancetothenear
targetis“L”(seeFigure3.1or3.2).Nowyoumust
movethetransitlaterallytowardtheneartarget
usingthecrossslide—buthowmuch?The
amountthatyoumovethetransitdependsupon
thegeometryofthesetup.Theequationtocalcu‐
latetheproperamountofshiftis:

TransitLateralShift=Lx(D2/D1)

where

D1=Distancebetweentargets
Figure3.1