16.13 ESTABLISHING REFERENCE PLANES
Since there is a good possibility that the off-line measurements will be taken at a different time
than the running measurements, it is suggested that vertical and lateral reference positions be
established. Understand that if you take a set of elevations on scale targets attached to the
machinery bearings as shown in Figure 16.46 when the equipment is off-line, then dismantle
the optical instrument and tripod, and if you go to set the instrument and tripod backup at a
later time, the question now becomes ‘‘what was the original elevation of the instrument when
the first set of vertical measurements were taken?’’
One of the primary considerations when using any method where you are observing points
on a machine case with respect to a remote observation point is to establish stable, nonmov-
ing reference ‘‘planes’’ in the vertical and horizontal directions that enable you to reestablish
or ‘‘buck in’’ to that same reference plane for comparison of your off-line and your running
measurements. This sounds easy but realistically, this is very difficult to accomplish. Remem-
ber you are trying to measure distances as small as 1 mil (0.001 in.).
1. Set the instrument stand at the
desired sighting location, attach the
alignment scope to the tripod or
instrument stand, and level the
stand using the “rough” circular
bubble level on the tripod (if there
is one on the tripod). Insure that
the stand is steady and away from
heat sources, vibrating floors, and
curious people who may want to
use the scope to see sunspots.
2. Rotate the scope barrel to line up with two of the four leveling screws
and adjust these two leveling screws to roughly center the split
coincidence level bubble in the same tilt plane as the two screws that are
adjusted as shown.
3. Rotate the scope barrel 90Њ to line up with the other two
leveling screws to completely center the bubble in the circular level as

shown.
4. If the circular level is still not centered, repeat steps 2 and 3.
Adjust these two leveling screws to first
adjust the circular level in one direction
and then
these two
screws for the
other
direction.
Split coincidence level
Circular level
Tilting screw
Leveling screw
s
How to level optical tilting levels and jig transits
10
10
5
5
0
30
50
40
60
10
10
5
5
0
30

50
40
60
FIGURE 16.44 How to level a tilting level or jig transit, parts 1 through 4.
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510 Shaft Alignment Handbook, Third Edition
The type of reference plane that you establish is somewhat dependent on the period of time
between the off-line measurements and the running measurements. If you plan on taking the
off-line and running measurements within a 2-h time period, then adhesive-backed targets
could be placed on walls or building columns or any fairly stable object. Examples of this are
shown in Figure 16.51 through Figure 16.54. If however the time period between off-line and
running measurements will be over 2 h or perhaps even days later, you should establish a
more stable reference position since building walls or structural steel could very well change
shape and position over a long period of time.
For vertical elevation measurements, it is suggested that one of the two methods be
employed. One way is to fabricate water-cooled pipe stands and attach adhesive-backed
targets to them as shown in Figure 16.55. It is recommended that at least two reference
points be established, usually one at each end of the drive train. Another way is to use an
invar extension rod contacting a tooling ball, which is rigidly attached to the concrete
foundation or baseplate or floor as shown in Figure 16.56.
For lateral or axial measurements, adhesive-backed targets can be placed on concrete
foundations or floors, or better yet, permanently anchored reference targets imbedded in
the concrete as shown in Figure 16.57.
How to level optical tilting levels and jig transits
8. The last step is to rotate the scope barrel
908 to line up with the two remaining
leveling screws yet to be fine adjusted.
Follow the same procedure as outlined in
steps 6 and 7 above. When these adjustments
have been completed, the split coincidence

bubble should be coincident when rotating
the scope barrel through the entire 3608
of rotation around its azimuth axis.
5. Once again rotate the scope
to line up with two of the
leveling screws as covered in
step 2. Adjust the tilting screw
to center the split coincidence
level on the side of the scope
barrel as shown.
6. Rotate the scope barrel 180Њ
and note the position of
the two bubble halves. Adjust the
two leveling screws in line with
the scope barrel so that the gap
between the two bubble halves is
exactly one half the original gap.
7. At this point, adjust the tilting screw so there
is no gap in the two bubble halves. Rotate the
scope barrel back 180Њ to its original
position and see if the two bubble halves are
still coincident (i.e., no gap). If they are not
adjust the two leveling screws and the tilting
level screw again as shown and rotate the scope
barrel back 180Њ until there is no gap
when swinging back and forth through the half
circle. The two leveling screws should be snug
but not so tight as to warp the mounting frame.
10
10

5
5
0
30
50
40
60
10
10
5
5
0
30
50
40
60
10
10
5
5
0
30
50
40
60
10
10
5
5
0

30
50
40
60
Gap
Half gap
No gap
Gap
Half gap
No gap
FIGURE 16.45 How to level a tilting level or jig transit, parts 5 through 8.
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Measuring and Compensating for Off-Line 511
Key considerations for capturing good readings:
.
Provide stable platforms for the optical scale targets
.
Establish several (minimum of two, three suggested) vertical, lateral, and axial reference
positions to ‘‘buck’’ back into
.
Scale target should be located as close as possible to the bearings since we are trying to
determine where the shafts are going (if the bearing moves, the shaft is sure to move with it)
.
Magnetic base holders should be used to hold the scale targets insuring a stable target
position
.
Clamp on circular level bubble sets should be used on the scale target to insure scale
targets are in a pure vertical position
1. Check calibration of the instrument (see Peg Test).
2. Select suitable scale positions at the inboard and outboard ends of each

piece of machinery in the drive train. The “platforms” that the scale targets
will be sitting on should be stable and slightly below the centerline of
rotation and usually near the bearings.You can use 2 in. 3 2 in. pieces of angle
bearing housing.Try to insure that the surface that the scale targets will
sit on is relatively level and flat. It is also advisable to install reference
stands at each end of the drive train and affix a “stick-um” crosshair target
to the reference stand.You can make these stands out of 3 in. or 4 in. pipe, fill
them with a water–glycol or antifreeze solution, insulate the pipe, bolt or
clamp them to the frame or floor, and monitor the water temperature to
insure thermal stability.
3. Set the optical instrument and stand at some remote reference point
away from the drive train where a stable point in space can be established
but close enough to maintain the maximum possible accuracy of the
readings.
4. Accurately level the instrument and take a set of readings at each target
scale mounted on the machinery when it is “off-line” (i.e., not running)
occasionally checking back to the reference targets at each end of the drive
train to insure that you are maintaining the same vertical elevation (i.e.,
shooting through the same horizontal plane).
5. Run the machinery at normal conditions and allow the equipment to
stabilize its position (this can take hours or even days).
6. Check the level accuracy and take a similar set of readings at each target
scale occasionally checking back to the reference targets at each end of the
drive train to insure that you are maintaining the same vertical elevation.
7. Compare the off-line set of readings to the running set of readings to
determine the amount and direction of the movement of each scale.
Optical alignment OL2R procedure for
vertical (up and down) measurements
12
3

2
468
2
4
68
2
468
Optical
Scale
Target
12
3
2
4
68
2
4
68
2
4
68
Optical
Scale
Target
12
3
2
4
68
2

4
68
2
4
68
Optical
Scale
Target
12
3
2
4
68
2
4
68
2
4
68
Optical
Scale
Target
Reference
stand
Reference
stand
Scale targets
FIGURE 16.46 How to take optical vertical OL2R measurements.
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512 Shaft Alignment Handbook, Third Edition

.
If possible, try to keep the scale targets in place from OL2R conditions.
.
Keep the scale target holding platforms clean.
.
Move slowly when working around the tilting level or jig transit and stand (if your foot or
arm bumped the stand, it is probably not in the level or in the same vertical or horizontal
plane any more).
.
Readings should be taken at night when equipment is located outdoors to prevent
thermal instability of the tripod or stand when the sun heats or cools the stand.
1. Check calibration of the jig transit (see Peg Test). Two people are
required to do this procedure—the scale target holding person and the
observer.
2. Select suitable scale “anchor” points at the inboard and outboard ends of
each piece of machinery in the drive train. The points or “anchors” that the
scale targets (and probably extension rods) will be touching should be stable
and directly above or below the centerline of rotation and usually near or at
the bearings. You can have tooling balls firmly affixed to the machine care
or bearing housing as the “anchor” points to hold the scale target against for
reference.
3. Set the jig transit and stand at some position along one side of the drive
train where a stable point in space can be established insuring that
measurements can be taken at each bearing location when the scale target or
extension rod is placed at each “anchor” point at every bearing location.
Orient the optical micrometer on the scope barrel to allow variation in the
position of the vertical crosshair when the micrometer barrel is rotated.
4. Accurately level the instrument, then loosen the vertical sweep axis screw
allowing the scope to tilt up and down. Affix several (at least two) adhesive
crosshair targets to the foundation or floor along the full length of the drive

train establishing a vertical reference line or plane. Take a set of readings at
each bearing location by holding the scale target or extension rod when
placed at each “anchor” point when the machinery is “off-line” (see “waving
scales”) occasionally checking back to the adhesive crosshair targets attached
to the foundation or floor to insure that you are maintaining the same
horizontal position (i.e., keeping in the same vertical reference plane).
5. Run the machinery at normal conditions and allow the equipment to
stabilize its position (this can take hours or even days).
6. Check the level of accuracy and take a similar set of readings at each bearing
location occasionally checking back to the adhesive crosshair targets
attached to the foundation or floor to insure that you are maintaining the
same horizontal position.
7. Compare the off-line set of readings to the running set of readings to
determine the amount and direction of the movement of each scale target and
bearing location.
Optical alignment OL2R procedure for
horizontal (side-to-side) measurements
12
3
24
6
8
24
6
8
24
6
8
Optical
Scale

Target
12
3
24
6
8
24
6
8
24
6
8
Optical
Scale
Target
12
3
2
4
68
2
468
2
4
68
Optical
Scale
Target
12
3

2
4
68
2
468
2
468
Optical
Scale
Target
Jig transit
“Anchor”
points
Scale targets
Line of sight
Extension rod (invar)
Top
view
Reference targets
10
10
5
5
0
30
50
40
60
FIGURE 16.47 How to take optical horizontal (side-to-side) OL2R measurements.
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Measuring and Compensating for Off-Line 513
.
Capture a set of readings from OL2R conditions and another set of readings from R2OL
conditions to determine if there is a consistent pattern of movement.
.
Several sets of measurements (minimum of two, three suggested) should be taken for the
off-line measurements and also for the running measurements to verify that the equip-
ment is in both a stable off-line and stable running position.
Advantages:
.
Extreme accuracy possible (1–2 arc seconds) with a precisely leveled and calibrated
instrument
.
Excellent repeatability if instrument is properly calibrated, consistent positioning of scale
targets is done, precise leveling is achieved, and stable reference points have been
established
Jig transit
“Anchor” point
Scale target
Line of sight
Top view
12
3
2468
2468
2468
Optical
Scale
Target
“Waving” scales

To insure that accurate readings
are taken for the side-to-side
measurements, the scale
target must be at a 908
angle to the line of sight. By
“waving” the scale target toward
and away from the observer (jig
transit), a precise 908
angle will be obtained when the
minimum reading is observed.
90Њ angle required for accurate reading
10
10
5
5
0
30
50
40
60
FIGURE 16.48 How to take accurate optical horizontal measurements.
FIGURE 16.49 Jig transit and scale target on outboard pump bearing for lateral measurement.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 514 6.10.2006 12:03am
514 Shaft Alignment Handbook, Third Edition
.
Tremendous versatility and range of possible measurement points
.
Measuring instruments can usually be placed away from heat sources
Disadvantages:
.

Knowledgeable, patient, and dedicated personnel required for successful measurements
and evaluation of data.
.
If the machinery is vibrating excessively, it appears that the scale targets cannot be
focused when taking the running measurements (a strobe light could be used to measure
the high and low points of the target by tuning the strobe slightly off the vibration
frequency of the object it is sitting on however).
.
Scale and reference target holding devices usually need to be custom fabricated and
carefully placed to insure long-term stable position.
.
Instrumentation, targets, and fixturing relatively expensive.
16.14 ALIGNMENT BARS WITH PROXIMITY PROBES
This method falls into the category of observing movement of one machine case with respect
to a position on the other machine case. This device was invented in the early 1970s by Ray
Dodd while working at Chevron. The machinery alignment bar OL2R system is based on the
principle of the reverse indicator method explained in Chapter 7.
Two ‘‘bars’’ are used, a ‘‘probe bar’’ and a ‘‘target bar.’’ The probe bar is attached near the
inboard (coupling end) bearing as close as possible to the centerline of rotation on one
machine case. The target bar is attached near the inboard (coupling end) bearing as close as
possible to the centerline of rotation on the other machine case. The probe bar and target bar
‘‘shadow’’ each other but they do not touch. Four proximity probes are attached to the probe
bar, two vertically oriented probes and two horizontally oriented probes. These probe sets are
mounted at two locations along the length of the bar, which observe two positions on the
FIGURE 16.50 Holding scale target with invar rod extension for lateral measurement.
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Measuring and Compensating for Off-Line 515
FIGURE 16.51 Adhesive-backed target attached to I-beam.
FIGURE 16.52 Adhesive-backed target attached to I-beam.
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516 Shaft Alignment Handbook, Third Edition
FIGURE 16.53 Transit with scale target in background.
FIGURE 16.54 Adhesive-backed target attached to wall.
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Measuring and Compensating for Off-Line 517
target bar. The targets could be blocks of steel attached to tubing or they could be the target
bar surface itself as shown in Figure 16.58 and Figure 16.59.
Before starting the drive train when the machinery is off-line and in a stable position, a set
of gap readings are taken on each of the two vertically oriented probes and each of the two
horizontally oriented probes. The drive system is then started up and operated under normal
running conditions until the probe gaps have stabilized. Relative machinery casing movement
can be determined by comparing the gaps on each probe before and after the equipment is
running. Strip chart recorders (or similar devices) can be set up to monitor the rate of change
of gap during warm-up and on-line operating conditions and to see when the positions have
stabilized (Figure 16.60).
Key considerations for capturing good readings:
.
The probe and target bars should be attached to each machine case as close as possible to
the centerlines of rotation to accurately determine shaft motion, not casing expansion or
bearing housing warpage (see Figure 16.26).
.
Important to have target surfaces at precise 908 angles to the proximity probes.
.
The bars can be positioned inside or outside the coupling guard or shroud with precau-
tions taken to prevent excessive vibration of the bars from coupling windage if mounted
inside the guard.
.
Capture a set of readings from OL2R conditions and another set of readings from R2OL
conditions to determine if there is a consistent pattern of movement.
Floor

Machinery foundation
Anchor bolts
Drain
3 in. or 4 in. pipe filled with water–glycol
solution and temperature
monitored for stability
Reference target
Insulation
FIGURE 16.55 Water-filled pipe reference stand.
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518 Shaft Alignment Handbook, Third Edition
Floor
Reference tooling ball
Invar extension rod assembly
Scale target
24
68
0
000
0
1
24
68
11111
2
24
68
2222
2
3

24
68
33
3
3
3
4
24
68
44
4
4
4
5
24
68
55555
6
24
68
6666
6
7
24
68
77777
8
24
68
8

888
8
9
24
68
99999
10
Machinery foundation
FIGURE 16.56 Invar rod and scale contacting tooling ball on foundation.
FIGURE 16.57 Permanent floor target.
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Measuring and Compensating for Off-Line 519
Base
mounted through bracket
to bearing housing
of driver machine
(a)
Indicator block
Probe mount
Airframe
tubing
Stiffener
Base
mounted through bracket
to bearing housing
of driven machine
Eddy probe
driver (1 of 4)
Extension
cable (1 of 4)

Eddy
probe
(2 of 4)
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520 Shaft Alignment Handbook, Third Edition
Flexible coupling and shaft ends
(b)
The target bar can
be attached to
either the driver or
the driven unit
The probe bar can be
attached to either the driver
or the driven unit
Proximity
probe
Proximity
probe
Proximity
probe
FIGURE 16.58
Alignment bar arrangements. (Upper diagram: Courtesy of Scientific
Atlanta
=SKF Condition Monitoring, San Diego, CA. With permission.)
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Measuring and Compensating for Off-Line 521
Advantages:
.
Fairly accurate measurements possible with proper setup.
.

Capable of measuring movement in vertical and horizontal directions.
.
Can continuously monitor positions of machinery without disturbing sensors or bars.
.
If the machinery is vibrating excessively when taking the running measurements, the
proximity probes average the oscillation effectively to insure accurate distances between
the probe tips and the targets.
.
Can be equipped to measure axial growth if desired.
Disadvantages:
.
Knowledgeable, patient, and dedicated personnel required for successful measurements
and evaluation of data.
.
Custom brackets and bars have to be designed, fabricated, and carefully installed on each
machine case as close as possible to the centerline of rotation.
.
If the machinery is moving considerably from OL2R conditions, the proximity probes
can bottom out on the target or move out of the linear range of the probes.
.
Thermal casing distortion where the probe and target bars are attached could result in
data that are not representatives of the movement of the centerline of rotation of the
shafts.
.
Somewhat expensive since custom braces and bars have to be fabricated; probes, cables,
proximitors, readout devices, and power supplies have to be purchased.
16.15 APPLYING LASER–DETECTOR SYSTEMS FOR OL2R MEASUREMENTS
Laser–detector systems can also be used to measure OL2R machinery movement in the
machine case to machine case measurement category.
In a very simple setup, where small amounts of relative movement between machinery cases

is present, a laser (or laser–detector depending on what system you use) could be mounted at
or near the centerline of rotation of one machine near the inboard bearing, and the detector
(or prism depending on what system you use) could be mounted at or near the centerline of
rotation of the other machine near its inboard bearing as shown in Figure 16.61. With the
machinery off-line, the laser–detector system can be oriented to have the laser strike in the
Probe bar
Target bar
“H”-shaped base to allow for
positioning the bar in the up
and down direction
“H”-shaped base to
allow for positioning
the bar in the sideways
direction
End view of bars
and probes
Angle iron
FIGURE 16.59 Fabricated alignment bar design.
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522 Shaft Alignment Handbook, Third Edition
center of the detector targets. The laser–detector system is kept in place on the machine cases
and the unit started up and operated until movement stops. If movement occurs between the
machine cases, the laser will be striking at a different position in the photodetector.
With the plethora of laser shaft alignment systems in existence, it is somewhat amazing to
find out that very few people have tried to use their systems for this purpose. The underlying
The probe and target
bars can be mounted on
either machine case but
you have to know
what is mounted where.

The distances from
the inboard feet to
the points where the
proximity probes are
taking readings on
the target bar must be
known, as well as the
orientation of the
horizontal probes.
The gap changes from
off-line to running (or
vice versa) need to be
recorded. Remember to
capture not only the
amount of the gap change
but also the direction
(increasing gaps means
the probe moved away
from the target).
Proximity probe alignment bar system
Proximity probe alignment bar system
Proximity probe alignment bar system
Where is the bracket holding the probes mounted?
compr
Select the mounting location for the bracket that is holding the proximity
probes (i.e., which machine will you attach the prox probe bracket to?).
compr
comprstm turb
stm turb
To operate this window

stm turb
stm turb
stm turb
OK
compr
Toward
mils
mils mils
Vertical gap change
mils
26 16
13
7
Vertical probes
Horizontal probes
Vertical probes
Are the
horizontal probes
on the
side of the target blocks?
5.5
2.5
in. in.
in.
3
Enter the four distances shown. Determine the
orientation of the target blocks with respect to
the horizontal proximity probes and enter the
direction. When done, press the “OK” button.
in.

10
OK
To operate this window
North
South
Horizontal probes
“Target”
bracket
“Target”
bracket
compr
Lateral gap change
Away
Toward
Away
Toward
Away
Toward
Away
FIGURE 16.60 Alignment bar setup.
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Measuring and Compensating for Off-Line 523
reluctance seems to originate from the difficulty in mounting the lasers and detectors to the
machine cases. Since there is such a wide variation in machinery design, custom brackets are
usually required to hold the equipment in place similar to those shown in Figure 16.62 and
Figure 16.63. These brackets must not only hold the laser and detector in a stable position,
but also the laser and detector need to have positional adjustments for centering the beam.
Additionally, if laser–detector–prism systems or two single-axis laser–detector units are used,
two sets of laser–detector prisms are needed to capture all the required information (vertical
offset, vertical angularity, horizontal offset, and horizontal angularity). With mounts having

a precise 908 rotation feature, one set of such two-axis equipment is sufficient. More detail on
such mounts will be given later.
Universal laser–detector mounting brackets can also be purchased as shown in Figure 16.64
through Figure 16.67. These brackets have the capacity to rotate the laser–detectors through
a precise 908 arc to capture all of the measurements needed as mentioned previously, thus
avoiding the need for two sets of laser–detector equipment.
FIGURE 16.61 Basic setup of laser–detector systems used to measure OL2R movement.
FIGURE 16.62 Laser–detector–prism systems setup on custom mounts measuring gear and compressor
OL2R movement. Alignment bar setup also used for comparison.
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524 Shaft Alignment Handbook, Third Edition
If a considerable amount of movement occurs between the machinery cases, the laser beam
could potentially traverse outside of the detector target surface area, inhibiting complete and
accurate OL2R measurements. Another type of laser–detector mounting system was created
to overcome this problem and is referred to as the plug in back zeroing laser target (PIBZLT)
mounts as shown in Figure 16.68 through Figure 16.75. These mounts have been designed
such that it will allow attachment of different types of lasers, detectors, or prisms, with the
capacity to remove and install them repeatably with good remounting precision. There is a
ball pivot placed in between the laser–detector mounting plate and the machine case attach-
ment plate with adjusting screws to tilt or pitch the laser or detector, enabling one to zero the
FIGURE 16.63 Permalign systems mounted across coupling. (Courtesy of Pru
¨
ftechnik, Ismaning,
Germany. With permission.)
FIGURE 16.64 Permalign M3 brackets and laser–detector mounted across coupling. (Courtesy of
Pru
¨
ftechnik, Ismaning, Germany. With permission.)
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Measuring and Compensating for Off-Line 525

laser–detector system. Tooling balls are placed at the twelve-, three-, six-, and nine o’clock
positions on both the backing and mounting plates to measure the change in position of the
mounts as shown in Figure 16.71. By measuring the position of the mounting and backing
plates via the tooling balls with the machinery off-line, adjusting the laser–detector to rezero
the beam, and then measuring the position of the mounting and backing plates via the tooling
FIGURE 16.65 Permalign M3 brackets and laser–detector mounted across coupling. (Courtesy of
Pru
¨
ftechnik, Ismaning, Germany. With permission.)
FIGURE 16.66 Laser–detector OL2R mounts. (Courtesy of Vibralign Inc., Richmond, VA. With
permission.)
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526 Shaft Alignment Handbook, Third Edition
balls with the machinery running, the OL2R movement can be measured. The tooling ball
measurements taken with the PIBZLT system are based on the face–face measurement
method (see Chapter 14 for reference). The back zeroing feature greatly extends the meas-
urement range. It also corrects for laser target poor linearity if this is present (30%–40%
linearity error found on some targets at range limits).
Key considerations for capturing good readings:
.
The laser–detector mounts should be attached to each machine case as close as possible to
the centerlines of rotation to accurately determine shaft motion, not casing expansion or
bearing housing warpage.
FIGURE 16.67 Laser–detector OL2R mounts. (Courtesy of Vibralign Inc., Richmond, VA. With
permission.)
FIGURE 16.68 Plug in back zeroing laser-target mounts. (Courtesy Murray & Garig Tool Works,
Baytown, TX. With permission.)
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Measuring and Compensating for Off-Line 527
.

Mounting devices must be stable and rigid enough to maintain a precise position of the
lasers and detectors even under moderately long time periods with machinery running
and vibration present.
.
Accurate positioning mechanisms for laser and detector required on mounting fixtures.
FIGURE 16.69 Close-up of four-axis laser target on PIBZLT mount. (Courtesy Murray & Garig Tool
Works, Baytown, TX. With permission.)
FIGURE 16.70 Side view of PIBZLT mount. (Courtesy Murray & Garig Tool Works, Baytown, TX.
With permission.)
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 528 6.10.2006 12:03am
528 Shaft Alignment Handbook, Third Edition
.
Capture a set of readings from OL2R conditions and another set of readings from R2OL
conditions to determine if there is a consistent pattern of movement.
Advantages:
.
Fairly accurate measurements possible with proper setup.
.
Capable of measuring movement in vertical and horizontal directions.
.
Can continuously monitor positions of machinery for moderate periods of time with
stable fixtures.
.
If the machinery is vibrating excessively when taking the running measurements, the
photodetector can average the position of the center of the ‘‘bouncing’’ laser beam fairly
accurately.
Disadvantages:
.
Knowledgeable, patient, and dedicated personnel required for successful measurements
and evaluation of data.

.
Other light sources, steam, water vapor, etc. can affect the ability to capture accurate
readings.
.
If the machinery is moving considerably from OL2R conditions, the laser beam can move
out of the range of the photodiode surface area unless the mounts have the capability of
getting positioned knowing what the before and after positions were (e.g., PIBZLT
mounts).
.
Custom brackets have to be designed and fabricated or purchased and carefully installed
on each machine case as close as possible to the centerline of rotation.
.
Possibility of inaccurate measurements due to uneven thermal distortion of machine case
where the holding fixtures are attached.
FIGURE 16.71 Taking micrometer measurements on tooling balls on PIBZLT system. The four-axis
laser target is on the left mount and the laser source is on the right mount. (Courtesy Murray & Garig
Tool Works, Baytown, TX. With permission.)
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 529 6.10.2006 12:03am
Measuring and Compensating for Off-Line 529
.
Relatively expensive since lasers, detectors, readout devices, and mounts have to be
purchased.
.
Incapable of measuring axial shaft or casing movement.
Determine which laser
system will be used with
the mounts. The data
capture sequence will be
slightly different depending
on which system is used.

Select where the lasers
and where the detectors
will be mounted.
Measure the distances from
the mounting locations of
the lasers and detectors
to the pivot point in the
PIBZLT mount and then to
the inboard feet of the
machinery (or other
reference points on the
drive train).
Laser, detector, and mount placement dimensions
Where will the laser be mounted?
What laser system will be used for the measurements?
Steam
turbine
Pump
Fixture Laser Inc.
Combi T212
T261 Permalign
TM
Digliaser
Quadra beam
Fixture Laser Inc.
Hamer Laser Instruments Inc.
Hamer Laser Instruments Inc.
INTRA Crop.
Pruftechnik
Pump

stm turb
stm turb
Pump
Laser reference
Select the machine where the laser will be mounted. The laser
is usually attached to the “stationary” machine.
Select which laser–detector system will be used to measure
the off-line to running machinery movement.
18.4375
OK
To operate this window
To operate this window
To operate this window
Enter the distance as shown. Try to
stay within ±1/8 in. on the dimensions.
When done, press the “OK” button.
3.5
−0.2188
4.2813
in.
in.
4
in.
in. in.
Target reference
File Edit Show Unit Moues Shortcuts Overlay line
File Edit Show Unit Moues Shortcuts Overlay line
File Edit Show Unit Moues Shortcuts Overlay line
FIGURE 16.72 PIBZLT setup information.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 530 6.10.2006 12:03am

530 Shaft Alignment Handbook, Third Edition
16.16 BALL–ROD–TUBING CONNECTOR SYSTEM
The ball–rod–tubing connector system, referred to as the BRTC system, falls into the
category of measuring OL2R machinery movement from one machine case to the other
machine case. The basic setup of the system is shown in Figure 16.76.
Two base blocks are attached to each machine case near their inboard bearings. Two
short rods with a round ball attached to the end of each rod are indexed through a hole in
Zero the laser beams into
the detectors by positioning
the tilt or pitch adjustment
screws on the mounts with
the machinery off-line.
After the beam has been
centered, measure the gaps at
all eight tooling ball points (four
on each mount) and record
the dimensions.
Start the machinery up and
allow sufficient time for the
readings to stabilize. Rezero
the beam by adjusting the tilt or
pivot screws.
File
stm turb
Off-line laser readings
Pump
Parallel
(in.)
Angular
(in/ft)

−0.0108
−0.0324
0.0311
Enter the data from the laser–detector readout unit for both the
parallel and angular beam positions in the vertical and horizontal planes.
0.0025
OK
To operate this window
To operate this window
Power
supply
Vertical
−00.0
00.0
Horizontal
Edit Show Unit Moues Shortcuts Overlay line
File
stm turb Pump
Top
0.56560
0.50318
0.55271
0.48635
South
Enter the averaged micrometer readings for all eight tooling ball
sets located on the target mount and laser mount when the machines
were off-line (i.e., not running)
Turnet
10
5

123
North
Bottom
OK
Off-line tooling ball distances
Edit Show Unit Moues Shortcuts Overlay Line
File Edit
stm turb
Pump
On-line laser readings
Parallel
(in.)
Vertical
−00.0
00.0
Horizontal
−0.0199 −0.0013
−0.0021
0.0841
Enter the data from the laser–detector readout unit for both the
parallel and angular beam positions in the vertical and horizontal planes.
Power
supply
Angular
(in/ft)
OK
To operate this window
Show Unit Moues Shortcuts Overlay Line
FIGURE 16.73 PIBZLT measurement information.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 531 6.10.2006 12:03am

Measuring and Compensating for Off-Line 531
If the beam has moved out of
the range of the detector,
rezero the lasers into the
detectors by adjusting the
tilt or pivot adjustment screws
on the mount. Measure the
distances between all eight
tooling ball pairs and record
the distances.
In the event that you are
unable to exactly rezero the
beam, record the X –Y
coordinates of the beams in
the detectors.
Note: The procedure shown may vary slightly depending
on the system used.
File
stm turb
0.56483
0.51675
0.50571
0.53818
0.48538
0.54840
0.54768
To operate this window
Enter the averaged micrometer readigs for all eight tooling ball
sets located on the target mount and laser mount when the machines
were on-line (i.e., running at “stabilized” normal operating conditions).

0.50012
OK
1 2 3
10
Turnet
5
On-line ball distances
On-line laser readings after rezeroing
Pump
Edit Show Unit Moues Shortcuts Overlay line
File
stm turb Pump
Power
supply
Parallel
(in.)
−00.0
00.0
Vertical
Horizontal
−0.0327 −0.0105
0.0027
To operate this window
OK
0.0317
Enter the data from the laser–detector readout unit for both the parallel
and angular beam positions in the vertical and horizontal planes after
repositioning the mounts to zero the laser beam back in the detector target.
Angular
(in/ft)

Edit Show Unit Moues Shortcuts Overlay line
FIGURE 16.74 PIBZLT measurement information.
FIGURE 16.75 PIBZLT system measuring movement of steam turbine and compressor. (Courtesy
Murray & Garig Tool Works, Baytown, TX. With permission.)
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 532 6.10.2006 12:03am
532 Shaft Alignment Handbook, Third Edition
each base block and clamped into place. Telescoping tubing is affixed to each ball end. A brace
is attached to each rod that spans out to the tubing connector that holds two proximity
probes (a vertical and a horizontal probe). Proximity probe target surfaces are attached to the
tubing connector.
Gap readings are taken at all four proximity probes with the machinery off-line. The BRTC
system remains attached to each machine case and the equipment is started up and allowed to
stabilize in its final operating position. Gap readings are taken again during operation. This
system is based on the shaft to coupling spool measurement principles adapted to measure
OL2R machinery movement.
Key considerations for capturing good readings:
.
The base blocks should be attached to each machine case as close as possible to the
centerlines of rotation to accurately determine shaft motion, not casing expansion or
bearing housing warpage.
.
During operation, onerodend should beallowed to ‘‘float’’toallow for anyaxial movement
of the machine cases and then locked in place to capture running proximity probe gaps.
.
The tubing connector must be able to freely pivot at each ball end.
.
Capture a set of readings from OL2R conditions and another set of readings from R2OL
conditions to determine if there is a consistent pattern of movement.
Center of
inboard foot bolt

Backside of ball
capture nut
Center of
proximity
probes
Center of
proximity
probes
Backside of ball
capture nut
Center of
inboard foot bolt
Recommended base block mounting positions
Off-line machinery positions
Running machinery positions
Angle B (off-line)
Angle A (off-line)
Angle B (running)
Angle A (running)
FIGURE 16.76 BRTC system basic setup and measurement principles.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 533 6.10.2006 12:03am
Measuring and Compensating for Off-Line 533
Advantages:
.
Fairly accurate measurements possible with proper setup.
.
Capable of measuring movement in vertical and horizontal directions.
.
Can continuously monitor positions of machinery without disturbing sensors or bars.
.

If the machinery is vibrating excessively when taking the running measurements, the
proximity probes average the oscillation effectively to insure accurate distances between
the probe tips and the targets.
FIGURE 16.77 BRTC system measuring OL2R movement of steam turbine and pump.
FIGURE 16.78 BRTC system measuring OL2R movement of motor and compressor.
Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C016 Final Proof page 534 6.10.2006 12:03am
534 Shaft Alignment Handbook, Third Edition