Brunson 75 Operation And Field Adjustment Manual

Models 771, 75, & 76-RH

Optical Tooling Transits

Instrument

Company

Operation and

Field Adjustment Manual

Helping the World Measure

Since 1927

www.brunson.us

Kansas City, Missouri

8000 E. 23rd Street

Kansas City, MO 64129

Tel: 816.483.3187

Fax: 816.241.1945



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



1 Operation and Adjustment Manual



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



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 Transits 2

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

3 Operation 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 Transits 4

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

5 Operation 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 Transits 6

7 Operation 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 Transits 8

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

9 Operation 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proc ess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 Transits 10

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

11 Operation 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 Transits 12

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

13 Operation 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 Transits 14

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

15 Operation 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 Transits 16

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

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Brunson 75, 75-H, 76-RH, 76-RH190, 76-RH190M, 771, 771-H Operation And Field Adjustment Manual

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