As part of our laser shaft alignment troubleshooting series, we have discussed Laser Shaft Alignment Troubleshooting: Part 1 Repeatability and Laser Shaft Alignment Troubleshooting: Part 2 Response to Corrections. In this final part of the series, we will discuss The Pipe Test.

In this series, we’ve examined some of the causes of errors in laser alignment measurements that can be encountered and how to remedy them. If you’ve gone through each of the possible sources of error and are still experiencing problems, there is a simple field test you can perform to ensure the laser alignment system’s functionality.



  • Mount the measurement heads 6 – 10” apart on to a piece of pipe of a diameter no less than two inches.
  • Start the horizontal shaft alignment program and enter the dimensions for the laser heads. Foot dimensions are not needed.
  • If V-blocks are not used, take measurements by rotating the pipe with your hands.
  • Take at least two separate measurements turning the shaft 360 degrees.
  • The coupling results should be zero or very close to it if the system is performing correctly

Laser shaft alignment systems are reliable tools that produce highly repeatable results and simplify shaft alignment. That being said, technicians need to know that the measurements they’ve taken have minimal uncertainty and errors. That is where calibration comes in. Sending your unit out for periodic calibration checks will ensure the reliability of your system.


by Diana Pereda

We previously discussed misaligned couplings and how to reduce failures when ultrasound and alignment meet in “Ultrasound and Alignment Meet at the Coupling to Reduce Failures.” In this follow-up blog, we will discuss how ultrasound and alignment come together to improve belt-driven performance.

Misalignment in belt-driven equipment is one of the leading causes of failures throughout the industry. It breaks down machines and often costs your company thousands upon thousands of dollars in repair expenses and unplanned downtime. Imagine if you could combine two technologies you may already be using to prevent some of these failures. Ultrasound and precision laser alignment will make your maintenance department ever more proactive than ever before.

Figure 1

Belts can be too loose, too tight, or be running on misaligned pulleys. Loose belts will slap and produce a noise similar to whiplash. Tight belts and misaligned belts will generate additional friction which will again be audible ultrasonically. Figure 1 is a sample time signal of slapping belts.

An easy way to detect and prevent failures is to add your belt driven machines to your ultrasound routes. It will require a few extra measurements on each route and some trending. However, the benefits will far outweigh the costs. By being able to tell when a belt system needs to be aligned and properly tensioned before it breaks down, we can be more proactive and less reactive.


Once the imminent failure is being detected, we can address it with a realignment of the belt drive unit using our Easy-Laser XT190 pulley alignment system. It is easy to use and it will provide the user with a PDF report for documentation and accountability.


This blog was inspired by Uptime Magazine’s article, “There’s Something in the Air”, July 2009, pp. 48-53, written by Thomas J Murphy with SDT Ultrasound Solutions.

Download our 5-Step Sheave Pulley Alignment Procedure which provides a simple and effective procedure for sheave pulley alignment of belt-driven equipment. 

by Diana Pereda

We previously discussed a lack of repeatability and identified some of the most common and easy-to-correct culprits in Laser Shaft Alignment Troubleshooting: Part 1 Repeatability. In this follow-up blog, we will discuss Response to Corrections.

Along with measurement repeatability, the laser alignment system’s ability to display the correct moves to bring the machines into alignment is crucial. If the machines do not respond to these corrections, you’ll be chasing moves throughout the alignment process – which isn’t fun!



Response to corrections is how the moves given by the alignment system work out.

If the results don’t reflect the moves made, the following can be the causes:

  • Incorrect dimensions entered for the machinery. The alignment system relies on the correct dimensions being entered in order to predict the correct move amounts.
  • Coupling strain can cause small deflections in the machine shafts that can misreport the correct shaft centerlines to the alignment system. Precise measurements of the rotational centerlines is crucial in determining the misalignment between them.
  • Soft foot amongst other negative effects can hinder adjustment attempts.

In addition to the above considerations, environmental vibration, external stresses on the machines, and thermal effects can cause a lack of response to corrections. Identifying and accounting for these causes will make your alignment easier overall and help you get it done faster.

Watch our Shaft Alignment Know-How: Thermal Growth video to learn the importance of accounting for thermal growth on rotating equipment.


by Diana Pereda

Sometimes I will assist a customer on-site for shaft alignment.  The first thing I will ask is, “what is the tolerance you wish to achieve?” Many times I would be given a specification, but sometimes I would be told “we need it aligned to 1 thou.” 1 thou I would ask, where?  The answer would be “at the coupling and feet.”  I would then reply, “Well that depends…”

Assuming soft foot will be addressed and that correct targets (deliberate misalignment, if needed) are given, there is just one thing that needs to be aligned. That is both shafts. They should be set for a proper offset and angle at the coupling point.

Watch our Shaft Alignment Know-How: Offset & Angularity and learn about the concepts of Offset & Angularity as they relate to aligning rotating equipment.

Feet adjustments are what you move the machine to align it to achieve tolerance at the coupling, therefore, feet moves have no tolerance.  Feet adjustments vary depending on how far away or near they are to the coupling and to each other.  Think of a laser pointer. If you aim it at a wall close to you and slightly angle it, the beam will slightly move.  Should you aim in 20 feet away and slightly angle it, it moves much more.  Depending on the feet positions, the precision of the adjustments will be generally more critical if they are closer together than if they are farther apart.

Regarding the coupling, the most important part of the alignment, you should consult your alignment tolerance table. For example, see the Easy-Laser XT’s built-in ANSI tolerance table below:


To achieve excellent (***) tolerance for coupling offset, you need to be within +/- 1.6 thou.  Being within +/-1 thou can mean achieving either -1.0 thou or +1.0 thou, which is still within the excellent tolerance of +/- 1.6 thou.  Being within +/- 1 thou offset at the coupling also means that you are within acceptable (**) and minimal tolerance (*) standards.

It is an entirely different case for the angle.  The excellent tolerance is 0.4 thou/in, the acceptable is 0.7thou/in and the minimal is 1.3 thou/inch.  1 thou of variation can throw the alignment angle at the coupling completely out of alignment!  Now is the spec unreasonably tight?  Absolutely not!  It is expressed in thou/in.  If you had a typical 10” coupling, 1 thou out is equivalent to a coupling gap of 10 thou out, and this gets magnified for large couplings!

In conclusion, be careful about following the dogma of “1 thou” being acceptable.  It is important to follow your required tolerance specifications.

Request your complimentary copy of our Shaft Alignment Fundamentals Wall Chart which highlights the ANSI/ASA Shaft Alignment Tolerances as well as information and guidelines for the implementation of good shaft alignment of rotating machinery, best practices, soft foot, tolerances, thermal growth, and much more!

by Diana Pereda

Misalignment in rotating equipment is one of the leading causes of failures throughout the industry. It breaks down machines and often costs your company thousands upon thousands of dollars in repair expenses and unplanned downtime. Imagine if you could combine two technologies you may already be using to prevent some of these failures. Ultrasound testing and precision laser alignment will make your maintenance department more proactive than ever before. For example, we all know couplings can be misaligned, and couplings can be loose. Infrared training tells us that a misaligned coupling generates heat. This heat is generated by the periodic friction caused by the coupling being squeezed with each revolution. Remember, friction we can hear. Therefore, a misaligned coupling will generate a periodic ultrasound signal like the one shown in Figure 1.

Figure 1

If you are already using ultrasound and laser shaft alignment, you are already there.  All you have to do is add the coupling data point to your current ultrasound routes. This simple step combined with some trending will tell you when you need to check and correct the misalignment on the pieces of equipment along the route. Furthermore, a loose coupling will generate an ultrasound signal caused by the fretting of the coupling halves rattling. This fretting will be harsher and less periodic in nature than misalignment (see Figure 2).

Figure 2

Once the imminent failure is being detected, we can address it with a realignment of the machines using an Easy-Laser laser alignment system like the XT770. It is easy to use and it will provide the user with a detailed PDF alignment report for documentation and accountability.

Ultrasound Coupling Inspection with Flexible Sensor

For more information on Ultrasound coupling, refer back to our blog, “Airborne Ultrasound Keeps Flexible Couplings Reliable” as shown above featuring our SDT340 Ultrasound Solution.


This blog was inspired by Uptime Magazine’s article, “There’s Something in the Air”, July 2009, pp. 48-53, written by Thomas J Murphy with SDT Ultrasound Solutions.

Download our 5-Step Shaft Alignment Procedure which provides a simple and effective procedure for shaft alignment of rotating equipment.

As an additional resource, we recommend watching, “Utilizing Ultrasound for Reliable Coupling” a presentation by Robert Dent with SDT Ultrasound Solutions

by Diana Pereda

What is repeatability?

Repeatability is the consistency of measurement results between consecutive sets of readings.

Laser alignment systems are capable of producing highly repeatable and reproducible measurements with just a few components attached to rotating machinery. When troubleshooting the cause(s) of lack of repeatability, it is helpful to try to identify some of the most common and easy-to-correct culprits.


Having a lack of repeatability can be caused by:

  • Loose components such as measurement units or brackets. These components should be affixed to the shafts and should be tightened to prevent slipping or rocking of any kind.
  • The measurement unit assembly should not rub on or strike any stationary component during a sweep measurement.
  • Backlash effects due to play in the coupling should be minimized.
  • If measuring using a sweep function, care must be taken to keep the rotation going in only one direction during measurement. Never let the heads rotate in the opposite direction.
  • Use the appropriate measurement mode for the machines: i.e. sweep, multipoint, 9-12-3, etc.

Establishing repeatability of the alignment system is one of the most important steps in shaft alignment. It can make the difference between an easy-to-accomplish job or a job where you’re chasing your corrections.

Watch our Shaft Alignment Know-How: Repeatability video and learn more about the importance of achieving repeatability of measurements before making alignment corrections.

by Diana Pereda

Pump and Motor Skid packages are essential pieces of rotating equipment that come as a complete package, with both machines mounted on a “skid”.  They are aligned at the factory and then shipped to the location to be installed at the facility.  If the skid was aligned at the factory, is it unnecessary to align it after the skid is mounted to the floor? The answer is No!

While the skid package was factory aligned, even precisely using a laser alignment system, you can almost guarantee it will not be in an aligned condition after installation on the floor.  One factor to consider is that this package probably travels long distances to reach its destination. It probably undergoes a lot of physical interaction during this process, such as being unpackaged, lifted, moved, hoisted, and set into place. In essence, it gets “bumped around” a lot.

Then, the skid itself is going to be placed on a concrete or steel support structure. Ideally, it is set level with jack bolts and gets get grouted into place for concrete installations.  This should result in a solid, flat, and level installation.  However, most installations involve simply bolting the skid directly to the concrete.  For machine installation requirements, concrete is usually far from flat and level. It will most definitely twist or deform the skid frame as it conforms to the surface of the concrete.  This will change the factory alignment of the machines which will then need to be addressed.

Shown below is such an installation where the skid was bolted directly to the concrete.  Precision alignment is needed, this one features the Easy-Laser E710 laser shaft alignment system to correct the alignment starting from the base (soft foot) all the way through to the final shaft alignment.  The fastest way to accomplish this is to follow the LUDECA 5-Step Shaft Alignment procedure.  Once the alignment is complete, a report is generated showing the skid package was properly aligned.


Ultimately, machines don’t care that alignment took place in the past.  They care about what the alignment is during operation.  Aligning pre-packaged skids after installation is non-negotiable for ensuring proper alignment.

by Diana Pereda

Image Courtesy of Brian Franks with Jettech Mechanical LLC.

Maintenance departments periodically schedule maintenance checks on their belt- or chain-driven equipment in order to confirm that a good alignment exists between the pulleys or sprockets, especially if evidence of premature wear on the belts, chains, or sprocket teeth is detected.

Visual Pulley Alignment

D90, DotLine Laser, SheaveMaster, or SheaveMaster GreenLine laser pulley alignment tool is ideal. It indicates misalignment in all three degrees of freedom (axial offset, horizontal angularity, and twist angle) instantly.

Digital Pulley Alignment

If you need accountability and documentation of the alignment, then the Easy-Laser XT190 will be the tool you need. The XT190 can be connected to your phone/tablet via the Easy-Laser XT Alignment App or can also be added to your existing Easy-Laser® XT440, XT660, and XT770 shaft alignment systems. Both interfaces will provide a visual representation of the misalignment, the capability of entering tolerances, and a PDF report for documentation purposes.

3 Quick Tips for Precision Alignment

  1. Always mount your laser pulley alignment tool on the smaller pulley and the targets on the larger one, for maximum resolution.
  2. Ensure that the mounting surfaces (pulley faces) are free of dirt or rust.
  3. Don’t forget to verify the proper tension of the belts (or chains) after the alignment.

Download our Pulley Alignment Guide Plus 5-Step Procedure. This guide provides information for the implementation of good pulley alignment of belt-driven equipment including terminology, alignment methods, belt maintenance, storage, and tensioning as well as a 5-Step Sheave/Pulley Alignment Procedure.

by Diana Pereda

Chris Greene is currently a technical trainer with Ludeca and has spent years before that as a lead mechanic as well as other related industry roles. Chris has been involved with reliability and installation since 2008. Chris attributes his mechanical proclivity to growing up in and around in his parent’s foreign car repair shop and tearing apart and making a mess of things around the place.

“Machines are built by someone with intent. When you stray from that intent, that’s when the machines start telling you it doesn’t want to work right.” Chris has found technicians with a solid knowledge of a machine are much more effective than simply having a worker applying a specific tool or ‘turning a bolt.’

A major aspect of adhering to the correct operation of a machine is installing it correctly. The installation dictates how it will run. Finding a defect or identifying problems at the outset can mitigate a host of issues down the road.

Even so, Chris talks about how the industry as a whole has used the installation as a place to cut costs. The newer the machine, often the bigger the issues they are regularly facing. The overall lifespan of equipment is dropping, and Chris believes these oversights and cost cuts have a lot to do with this.

“Industries as a whole have tried to save costs and a large percentage cut on installation costs”

A good solid machine check or geometric measurement to ensure base plants are on the same exact same plane can significantly enhance the lifespan of the equipment. But it is more than just proper alignment. It comes down to aspects as diverse as the long term suitability of the foundation. Many don’t take the time to look at basic issues like these. Are the anchors appropriately spaced? Do we have the correct base plates? These minor vibrations and movements due to little imperfections will take their toll over time.

Machine Installation Alignment 870x460

On Documentation:

Chris suggests that keeping proper documentation can be a boon to equipment installation and care. Documentation helps take employees to take ownership of a job and helps to ensure you can track the efforts and match them to the suggested practices. It also helps with the root cause analysis of problems that arise. From a business management perspective, it also helps you to explain and layout how a business is to someone in an office.

Commissioning Groups and Specifications:

Generally, companies will have something called a commissioning group, and they verify these checks and sign off on them. People show up and often go through the installation checklist with you, and if you miss something on this checklist, you may not get a warranty until you check it. This process validates everything is done properly from the site to the torque of bolts. Download our 5 Elements Machine Installation Infographic which outlines 5 important elements of machine installation including Foundation, Anchoring, Isolation, Baseplate Level, and Flat plus Alignment.

Chris explains how over the years, tolerances have opened up since so many companies struggled to meet the older specifications. You can see the difference between the two levels of care when you examine the machines after a few years of operation. These little changes in optimal specs can show significant differences in short amounts of time.

Using tools like the ANSI/ASA alignment standard, and specifically, the standards dictated by the manufacturers, help you to see what the bare minimum standards for a piece of equipment are. You should ask yourself if you can do better than these. Better standards can only prolong equipment life.

The one thing to help with success?

Chris answers that you should understand the specifications and make sure you are installing equipment right and exceeding those tolerances. Management needs to understand that letting technicians have the tools and knowledge to do the job right can benefit machines and their lifespan greatly.

“A couple of loose nuts behind the wheel can wreck an entire facility.”

Spend the time to set a machine up correctly, take that extra effort to look ahead, and see what that next problem is before you build it into the installation.

Hear more from Chris Greene in this podcast by James Kovacevic and learn to understand how the correct installation of equipment will set the stage for optimal operational quality and longevity.

by Diana Pereda

Often, when I get a report or a technical support call, if I see the user got a perfect “0-0”, I become immediately suspicious rather than celebratory.  What I mean by “0-0” is that the coupling results or feet corrections (or both) are perfect zeros.  There are times where that is possible, for example, this screenshot of the alignment that was taken out in the field as shown below:

0-0 Perfect Alignment 870x460

The numbers are close to zero, but not exactly zero. The point is there is at least some variation. Assuming the resolution is set to the nearest 0.1 mil, “0-0” would mean that that alignment is less than 0.1 mil, a very rare and impressive achievement!

Is “0-0” necessary? The answer is no because you have a shaft alignment tolerance for a given speed of rotation.  Lower rotation speeds require looser tolerances and higher rotation speeds have tighter tolerances.   Tolerances are to be used to your advantage so you know when to stop the alignment.  If the goal is perfect zeroes, it could be possible, but you will be working way too long to achieve a nearly impossible goal.  We suggest the use of the ANSI/ASA S2.75-201 standard tolerance as shown below:

ANSI-ASA-S2.75-201 Standard Alignment Tolerances 870x460
Click here to review and purchase your ANSI-ASA-S2.75-201 Shaft Alignment Methodology, Part 1: General Principles, Methods, Practices, And Tolerances

What happens if you do get “0-0” for your alignment?  I would advise checking the following to make sure this was not a user setup error:

  • Check the resolution. Is it set to 0.1 mil resolution (recommended)?  If it is set to 1.0 or even 10.0, the lowest number will default to zero.
  • Are you using the correct units? (i.e. metric vs imperial)
  • Is the measurement shown to repeat in the measurement table?  Is the alignment measurement reproducible?
  • Were the sensors mounted on each machine shaft?  Never mount the sensors on the coupling part that flexes, or you will get an incorrect reading.  If you mount on the coupling only, this doesn’t represent the alignment between the machines; you will have an incorrect setup and most likely show perfect alignment.
  • If you have a solid boss fit style rigid coupling, make sure the boss fit is separated to disengage the coupling with the bolts slightly loosened.  This allows the misalignment to be measured.  If the coupling is bolted, the shafts will be forced together, showing an incorrect near-perfect alignment.

Request your complimentary copy of our Shaft Alignment Fundamentals Wall Chart which highlights the ANSI/ASA Shaft Alignment Tolerances as well as information and guidelines for the implementation of good shaft alignment of rotating machinery, best practices, soft foot, tolerances, thermal growth, and much more!

by Diana Pereda

Correcting a shaft alignment problem brings a vast set of challenges to the workload of our mechanics, millwright, and engineers. Those issues could be in the form of physical constraints preventing movement or distortion from poor bases or pipe stress. They could be as simple and frustrating as soft foot or old bent shims. But, one of the most intimidating alignments out there is the spacer shaft, especially when it comes to extreme distances.

I am not an engineer—oh-oh, half of my readers just left—but for those of you still reading, I want to provide you with a few tips compiled by a few of us here at LUDECA to make your spacer shaft alignments with lasers easier. So, without wasting too much of your time, I refer you to the 5-Step Shaft Alignment Procedure.

Just kidding… sort of.

There are many different types of spacer shafts. So, what is a spacer shaft?

Spacer Shaft Alignment with Easy Laser XT

Picture 1

Generally speaking, a spacer shaft (spool, spider, jackshaft, or whatever you want to call it), is a coupling of some kind that spans more than 4″ or 101.6 mm between its flex planes. My goal in this blog is to provide five simple tips to help you align spacers without getting into the mathematical process. I’ll save those questions for the engineers. Keep in mind, these are suggestions for laser alignment of spacer shafts.

Spacer Shaft Tip 1:

Try to make sure you can square the two sensors to one another. By either using the inclinometers, lasers to targets, or really good eyesight – it tells you a lot if your sensors square up to one another. This seems like a simple or obvious tip (which is why it’s the first one) but, this also provides you with an indicator for TIP 2!

Spacer Shaft Tip 2:

There are two primary ways of aligning spacers: the Two-Step Method and the Single-Shot Method. Now that you can determine how bad your misalignment is – you can choose the method that fits best. The single-shot method is typically done when the alignment isn’t grossly out and the sensors would be mounted on the far ends of each spacer component. The two-step method is used when there is a significant amount of angle or offset to correct.  The sensors should be mounted across each flex plane of the spacer individually to close the angle at each.


Picture 2

Spacer Shaft Tip 3:

Soft Foot. If you are following our 5-Step procedure you probably understood that I went a little out of order. However, we needed to know which components we were moving first, right? Now that we have a plan we have a procedure. Soft Foot matters, and it should be corrected and fall within the allowable tolerance. Use this time to also correct any challenges that can be identified visually (clean the base, good shims, etc.) You may want to take a look at our Soft Foot Find and Fix Procedure for an outline of types of Soft Foot including causes and corrections. 

Spacer Shaft Tip 4:

Know your tolerances. There are 1,001 blogs and articles on spacer tolerances on the web. The best thing you can do is know what your tolerances are for that specific alignment. Yes, spacer tolerances can be more forgiving in terms of the required corrections at distances. However, there are many ways to represent those spacer tolerances. You could have a specification that is Angle/Angle or Offset/Offset or a combination of those. Make sure you are aware of the required values and representation.

Spacer Shaft Tip 5:

Patience. Don’t rush to get it done. Do it right so you don’t have to do it again.


Picture 3 and 4

So, when you find yourself facing a spacer shaft, spool piece, or jackshaft, take a deep breath and follow the same rules of alignment that experience has taught us. I would also like to thank Joel Chapman from Entech Sales & Service Inc. for a lesson in cooling tower alignment in the rain (the umbrella was for me, not the laser, it was very nice of him – picture 2). And, thank you Richard Armstrong of TRACE Reliability, a LUDECA, INC. solutions provider who makes our customers a priority. He shared pictures 3 and 4 of an ID Fan in Louisiana that measured 289” inches from sensor to sensor.

by Diana Pereda

Adjustable Chocks for Equipment Mounting

Adjustable chocks have been around for years and are a useful way to accomplish parts of machine mounting and alignment. In some circles, they have either a great or bad reputation. A lot of that reputation may depend on the application and how the chocks were installed.

Adjustable Chocks for Equipment Mounting

Adjustable Chocks vs. Shims

First, let’s discuss why a company might want to use an adjustable chock for machine mounting, instead of shims:

  • Adjustable for height. This means not having to stock lots of shims, in different sizes and thicknesses, to accomplish vertical adjustments in alignment.
  • Spherical top part. This accommodates issues with feet not being parallel (up to 4 degrees for some manufacturers) with the foundation or skid which eliminates the need for step shimming.
  • Easy Soft Foot corrections. When an air gap is found, simply fill the gap by adjusting the chock to fill the gap. (Zero Soft foot)
  • Reduced inventory. Instead of several shims in a kit for each piece of equipment, just reuse the existing chock for adjustments.

Now, let’s discuss why a company might not want to use an adjustable chock for machine mounting, instead of shims:

  • Lack of contact surface between mounting foot and base. How can this round element take the place of a full-footprint shim for secure mounting?
  • Transmission of Energy. Without the solid contact of that full-footprint shim, the energy will never be transmitted to the Inertia Block in the base; therefore, the equipment will shake itself to pieces.
  • Locked up chock. Once they have been in service for a while, they lock in place and have to be replaced for future alignments.
  • Loose chock. Upon inspection, the chocks have been found to be rotated down under the foot, and there is a gap/Soft Foot condition.

Adjustable Chocks for Equipment Mounting

The Cons of Adjustable Chocks

By looking at each of those concerns, answers can be found for how to mitigate the concern and better understand how adjustable chocks can (and cannot) be used. The design and engineering of these devices make them suitable for most applications, but not if selected and used incorrectly.

For the issue of lack of surface area under a foot to the mounting base, looking at the product catalogs show any number of configurations to increase the surface area. Using more than one at each foot, or having two under a foot but staggered. The simplest rule to use is to use the largest chocks that can fit, but with a catch. The top surface must cover at least 75% of the surface area of the mounting foot, and the bottom surface must have 100% of its surface area in contact with the base. Both of these surfaces must be clean.

This leads to the next issue, the transmission of Energy. If the correct size of the chock is selected, and the above rule for coverage is observed, then the Energy will transmit through the body of the chock just fine. The other thing to watch for is cleanliness. Both the bottom of the mounting foot and the top of the base should be clean – reasonable steel-of-the-truck finish (corroded, excessive mill scale or moon crater need attention, with a minimal primed surface for corrosion purposes. Any amount of paint, dirt, or debris can make for an uneven surface that could result in the bottom of the chock not sitting squarely. Sometimes, a bit of light sanding can go a long way towards promoting proper machine mounting. Check with chock manufacture for surface finish recommendations.

Now, for the locked-up chock. Oftentimes, comments are made that the machine being aligned is unable to be lifted by the adjustable chock. This is a misconception. The threaded chock is designed to lock under load. It is NOT designed for lifting or lowering the equipment.  Normally, equipment that is designed correctly will have vertical jack bolts, and this is what is used to establish the correct elevation for the machine, or, in their absence, use a hydraulic pancake jack or other suitable lifting devices. Beyond that, finding the chocks unable to rotate after being under a piece of equipment can usually be attributed to dirt and debris in the threads. It is a very common practice to lift the equipment on the vertical jack bolts just enough to remove the chocks. Thorough cleaning in a general solvent can remove the particles that restricted movement. After the cleaning, a thin coat of appropriate lubricant (often a specific compound recommended by the chock manufacturer) will help ensure movement. Protecting the cleanliness of the chock after alignment can be accomplished with a heavy protective spray. Anything that seals moisture and debris out is good, as long as it does not trap moisture (just to note: whatever you put on it will need to come off at some point to allow the chock to be reusable – be judicious or better yet contact your chock supplier).

Lastly is the concern of loosened chocks, which has been a topic of much discussion lately. The easiest way to explain this problem goes back to proper training. The technician performing the alignment needs to be mindful of how an adjustable chock is designed to work. The function of that chock is to support the machine. Prior to torquing the hold-down bolts, the machine needs to be resting on the chocks, not on the jack bolts.

The procedure boils down to using the jack bolts to establish the correct elevation, spinning all of the adjustable chocks up to firmly contact with the bottom of the machine, and then perform the final tightening.  (Fit all chocks at the same time!!) Back off all lifting and lateral adjustment jack bolts FULLY, then tighten the anchor bolts to the proper torque in the sequence specified by the equipment OEM

Do not tighten the anchor bolts with the jack screws or lifting bolts under load!

The purpose of adjustable chocks is to facilitate proper mounting of equipment, more efficient alignment operations, and a viable replacement for traditional shims. While they might not work for all applications, with proper implementation chocks can work for 90-95% of applications where larger spacing between the machine feet and the mounting base is required; rather than inserting a big pile of shims, a chock can make life easier for the technicians performing realignment. This requires an open flow of information from the design and installation of the equipment, all the way through to the day-to-day maintenance.

This post was written in collaboration with

by Diana Pereda

The consequences of positional change due to thermal growth in machinery as it pertains to shaft alignment are well documented. Methods for determining these changes and compensating for them are not only essential to the reliability of machines but can prevent catastrophic failure. It is therefore of great importance that these methods be carried out as carefully as possible—minimizing human error as much as possible to ensure effective results.

One often-overlooked consideration when performing shaft alignment measurement is the temperature and thermal stability of the very components used for these measurements. Brackets, lasers, sensors—all components that are susceptible to thermal growth. Changes in the intensity of sunlight, large shifts in ambient temperature during the job, and performing measurements too soon after bringing the components out to the machine can all lead to lack of repeatability and improper shaft alignment corrections.

XT Components snow cold thermal growth
Photo credit: Brian Franks with JetTech Mechanical LLC.

XT Components sun hot thermal growth


You can minimize the effects of these conditions in various ways:

  1. Always allow a suitable amount of time for the alignment system to acclimate to the environment in which you will be performing the measurements. For example, if the equipment is moved from a warm office or truck to a cold environment and measurement is begun immediately without giving the temperature of its components enough time to stabilize, performing the shaft alignment will be a bit like trying to hit a moving target. The brackets and/or laser and sensor housing will still be physically changing in dimensions until stabilization has occurred.
  2. If sunlight conditions are unstable where you are working try to keep the alignment components shielded from the sun. Direct sunlight striking the laser housing of a shaft alignment system can have an adverse effect on the reliability of the readings during a measurement.
  3. Keep portable heaters and air conditioning units away from the area. It is natural to want to work in a comfortable environment, but the unstable air currents caused by heaters or a/c’s can wreak havoc on measurement repeatability.
  4. And one more: if a heat source is intense causing heatwaves in the path of the laser beam, thereby distorting or refracting the laser beam and affecting your repeatability, a simple fan to blow air through that area can help to stabilize conditions or provide a uniformly turbulent atmosphere for the laser to travel through, allowing its true position to be accurately averaged.

Observing these principles while performing shaft alignment readings will allow you to achieve more stable and reliable results and thus help you to #keepitrunning.

For more information, check out our Shaft Alignment Know-How: Thermal Growth and learn the importance of accounting for thermal growth on rotating equipment.

by Diana Pereda

Soft Foot Measurement – It really is important!

On a recent visit to a power plant, they asked me to help them align a pump with their new EASY-LASER XT Alignment System.  It was a machine they had previously aligned with dial indicators, which they thought was “pretty good”.  The initial measurement showed a vertical offset of about 7 mils, so we removed all the shims and measured soft foot. The results are shown below.

Easy-Laser XT calculated Soft Foot As Found

As you can see, there was a significant issue.  We probed and found gaps under both the indicated feet.  The foot showing 32.6 mils showed a parallel air gap, whereas the foot showing 22.1 mils had an angular gap that required step shimming.

Once the soft foot was corrected we continued with the alignment, and achieved excellent results.

Easy-Laser XT Alignment Soft Foot as left

In later conversation, I learned that the motors had been too high for the pumps when installed, so the contractor ground down the feet with a wheel grinder!  That explains the soft foot issue!

Bottom line, ALWAYS check soft foot.  Not only does uncorrected soft foot make the alignment more difficult, it introduces stresses to the machine thus reduces reliability.

Download our Soft Foot: Causes, Characteristics and Solutions white paper for additional information that explains in depth the causes and characteristics of soft foot conditions and how to diagnose and solve them. 

by Diana Pereda


how to eliminate unbalance of a coupling

Many shafts have keyways cut into them to hold the coupling. “Keys” are pieces of square metal stock inserted to hold the hub in place.

If there are two (2) keys, one on each side of the coupling, you should not “align” the keys across the coupling. Instead, it is very important to ensure the coupling mass is balanced during installation. The mass of a key is balanced by setting the two keys 180 degrees apart from each other. If the keys are set on the same side, the coupling will induce a mass unbalance situation.

Often a vibration report will note a misalignment condition, but precision alignment techniques will not find any issue. This can lead to friction between the vibration analyst and the millwright. Keep the keyways 180 degrees apart. You will help improve the life of the coupling and keep the vibration low.


by Diana Pereda

Today’s advancements in technology have allowed many maintenance tasks to be performed more easily and efficiently. Such is the case with using a laser alignment system to accomplish sheave/pulley alignment. However, prior to setting up the laser system to perform the alignment, one important and often overlooked step is to measure and correct sheave run-out. Run-out refers to the situation when an object does not rotate exactly in the plane of the main axis of rotation. If not corrected, sheave run-out can cause a “rubber band effect” where the belt will become slack at one end while the other end quickly snaps into tension. Over time this repetition of the belt going slack then tightening will wear out the belt as well as the bearings and cause premature failure.

Run-out for sheaves can occur in two forms, radial (rim) and axial (face), and both need to be set within tolerance before performing the final alignment. The typical tolerance for radial run-out should not exceed 5 mils total indicated reading (T.I.R.) for high-speed sheaves (RPM of 1800 or greater) and no more than 10 mils for slower speed sheaves. The tolerance for axial run-out is no more than 0.5 mils T.I.R. per inch of sheave diameter for high-speed sheaves and no more than 1 mil per inch for slow speed sheaves.

Shaft Pulley Runout Check

Start by checking for radial run-out. If excessive run-out is measured, check if any shaft run-out is present. If shaft run-out is detected, the shaft may be bent which would require replacing the shaft before measuring for radial run-out on the sheave again. If no run-out was detected for the shaft, replace the sheave instead. Additionally, if the sheave is mounted on a tapered bushing, inspect and thoroughly clean both the inside and outside of the bushing to ensure the sheave is seated properly. Once the radial run-out is within tolerance, check for any axial run-out (or wobble) of the sheave. If axial run-out is measured, correct it by repositioning the sheave on the shaft. Once both types of run-out are within tolerance, install the new belts and perform the alignment.

If you’re looking for more information regarding pulley alignment, download our 5-Step Sheave/Pulley Alignment Procedure for a detailed breakdown of all the steps involved in good Sheave Alignment.

by Diana Pereda

Repost from Benchmark PDM Maad Blog

Coupling Alignment with EasyLaser XT770


Let us review this case study on a common issue when working on a pump and motor alignment done by Brian Franks, Owner and Field Service Technician of JetTech Mechanical.

He begins in the normal manner entering the distances of the machine. As you can see this is not a small machine (see Figure 1 below) – there are 57 inches between the motor’s feet and if you add all the measurements together you have 87 inches from the Stationary laser detector unit and the back foot of the movable machine (motor). Notice also that it is a spacer coupling.

Dimensions Screen Coupling Alignment with EasyLaser XT770

He continues doing the alignment work by taking a soft foot measurement on each of the machines and as you can see, there is very little, so we know it’s a stable base that the machine units are sitting on.

SoftFoot Screen SoftFoot Check with EasyLaser XT770

An important note is that they would need the coupling open/loose and the pipe disconnected in order to do this correctly.

The new ANSI standard (ANSI/ASA S2.75-2017/Part 1) allowable soft foot tolerance is two thousandths (0.002 thou or 2.0 mils) of shaft deflection and he is below this, so he is good to go. He documents it for his report.

He now performs the machines’ shaft to shaft alignment.

Notice that he’s removed most of the bolts from the coupling in order to allow the coupling to flex. This is a stiff coupling so you don’t want it locking up during the alignment and you also want to make as few moves as possible. So, this is a good practice. This also tells me they know what they are doing which is good.

The tool they are using is an Easy-Laser XT770 which is a dot laser system that can read in the horizontal and vertical plane.

Click here to read the entire case study “A Case Study on Why Pipe Strain Needs To Be Measured”

by Diana Pereda

Better Running Conditions from Precision Alignment

Caterpillar G3606 engine mated to Ariel JG D compressor

We performed an alignment as part of a yearly check on a Caterpillar G3606 engine mated to an Ariel JG-D compressor. Documentation was established to track the performance of the equipment before and after the alignment.

Before alignment:CAT Engine Load Before Alignment

The engine was running overloaded, consuming more fuel than budgeted, and over the permitted emissions levels. Initial readings found 0.012” of misalignment, and soft foot of 0.005” in a single mounting pad. Correcting the alignment to within 0.004″, using thermal growth targets, and correcting the soft foot, yielded the results needed for better running conditions.

After alignment:CAT Engine Load After AlignmentLoad was reduced by 6%, and fuel flow dropped by 10 cfm (saving $8800 per quarter). Emissions were well within permitted levels. This mitigated the possibility of a fine, which could be up to $33,750 PER DAY of non-compliance. All of these realized gains resulted directly from a precision laser alignment, carried out with precision tools, performed by properly trained technicians, to the standard of excellence required in today’s cost-aware environment.

by Diana Pereda

Bore Alignment on a Split Casing Pump

Our colleges at Benchmark PDM recently had a request from a customer to do some pump alignment. When we normally think about pump alignment, we usually think of shaft to shaft alignment. In this case, they wanted bore alignment. They were installing a brand-new pump and when they rotated the shaft, they could hear grinding.

Bore Split Casing Pump Closed

After further inspection one of the techs could see that the bearing housing had been moved – either during shipment or when it was stored. They could see that the dowel pin had been damaged.

Bore Split Casing Pump Open

Figure 1

If you pop the lid off this style of pump (See Figure 1 – photo courtesy of KSB Pumps Canada), we see the shaft and the center mounted impeller. On each side of the impeller we have the wear rings, which sit in the bores. Outside of that we have two stuffing boxes or seal bores and outside of these we have the bearing Journals which are also bores. All of these bore centers need to be colinear, meaning in a straight line.

The old traditional methods for doing this type of work was done using piano wire or a mandrel.  They would use the stuffing box or the wearing bores as reference points then measure to see if the bearing bores where in alignment. This method was “hit and miss” because its so difficult to set up and measure in this way. It also took a very long time.

Bore Alignment with Lasers

Using a laser-based measurement system has significantly reduced the time taken to do bore alignment. More importantly, it has improved the accuracy significantly. There are now automatic reports that go with the final bore alignment that has been completed – a documented history of the work is very important.

Bore Alignment with Lasers

Figure 2

There are many different applications where bore alignment is done using lasers. For example, extruder barrels that need to be aligned to a gearbox in the plastic industry, crankshaft bearing journal bores in diesel/natural gas engines or compressors in the oil & gas and energy industries and stern tube alignment in the shipping industry. These are just three examples that show how varied the type of alignment work is.

Click here to read the entire case study “Bore Alignment on a Split-Casing Pump

by Diana Pereda

You’ve always heard the adage, “S” Laser on the Stationary and “M” Laser on the Movable.”  In this day and age, however, this “truism” has almost become obsolete. You see, the concept of the “stationary” machine, per se, is obsolete. ALL machines CAN be moved if they really need to be (no machine grew out of the ground, like a tree!), so instead we emphasize that the “S” laser should be mounted on the machine that is “more difficult” to move (usually the pump because of the connected piping.)

The flexibility that all Easy-Laser XT-Series systems offer through their lock feet function, as well as the ability to freely flip or rotate the view of the machines to suit your needs, means that you no longer need to concern yourself with “stationary” machines. Your real goal is to find the easiest and most expedient way of aligning your machines. In some cases this may mean moving one pair of feet on the pump just a tiny bit to keep from having to move the motor feet a lot. This means you can save yourself from becoming bolt-bound, or base-bound (not enough shims left under the feet to be able to come down.)

Traditionally, you always try to set up so that your Stationary (or Hard-to Move) machine is on your left, and your Movable machine is to your right. But what if your pump and motor are mounted close beside a wall, and you can only access the machines from one side? As luck and Murphy’s law would have it, that side is always “the wrong side”, with your pump on the right and the motor on the left, instead of the way you are used to seeing them. No matter! Still mount your “S” laser on the pump. Now, since the Easy-Laser XT system wants to move the right machine by default, you can now employ the “Mirror” feature, which will automatically swap the view of your machines left and right, so you can see them the way they really are in the field, and easily move the left machine instead.

Easy-Laser Dimensions Screen Traditional Setup vs Mirror ViewIf you have two equally hard-to-move machines, each of which you would ordinarily like to consider stationary (such as a heavily piped little steam turbine driving a heavily piped compressor), then it really just boils down to which machine (or combination of feet on both machines) is the most expedient to move. Just mount the “S” laser on the on the left as usual. You can always use the lock feet function to declare the machine on the right stationary and make the machine on the left movable, or ask the tool to make any combination of feet movable so as to find your smallest possible moves or optimal combination of moves to solve bolt-bound or base-bound situations in the field. The Easy-Laser XT products are especially versatile for this, since they let you explore fully optimized centerlines (move ALL the feet in the train), as well as under-constrained and over-constrained centerlines, to cope with the exigencies of the situations you encounter in the field.

Lastly, if you ever need to compare your alignment or your target specs to a drawing or to someone else’s report that shows the machines the other way around from the way you set up, you can always use the Mirror functionality to look at your results from the other side. You use this feature “after the fact”—in other words, after your setup is already complete, with readings taken and results obtained, you can still always rotate the view and see your results as if you had walked around to the other side of the machines.

     Easy-Laser Results Screen Original View vs Mirror View

To summarize, the concept of “Stationary” and “Movable” is history. Use the Mirror feature right at the beginning, when you set up, to make your setup conform to your actual situation in the field. Use the Lock Feet Function to make any machine movable or stationary, and to explore “best possible” correction alternatives. Lastly, you can also use the Mirror feature to look at your alignment differently, after it’s already done.

by Diana Pereda

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