Posts tagged with: Alignment tolerances

Pipe Strain Was the Issue

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By on July 13, 2017

Have you ever struggled with a precision shaft alignment, even though you did everything right? (Preformed the pre-alignment steps, controlled backlash, etc., etc.) So, what was different? Maybe it was pipe strain. An alignment check of a new installation of a 40 HP, 3600 RPM motor/pump  revealed the vertical angular misalignment was 3.2 times the […]

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Is there such a thing as “Too Good” of a Precision Shaft Alignment?

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By on April 6, 2017

This question comes up frequently in our Shaft Alignment Best Practices training classes. The result screens below both show two different aligned machines meeting 3600 tolerances.   The question is; is one better than the other? There has been a lot of discussion about this very topic. The theories are abundant and points of view […]

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Coupling Tolerances vs. Shaft Alignment Tolerances, What’s The Difference?

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By on June 24, 2016

Plenty! This question still comes up fairly often in our training classes. If you look any of the coupling manufactures installation instructions there is a chart for the maximum allowable misalignment based on the coupling size. These tolerances are for the coupling, what about the machines the coupling connects? Shaft alignment tolerances are more about […]

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Repeatability vs. Desired Outcome in Shaft Alignment, Part 2

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By on December 2, 2015

In my last post, we looked some reasons for non repeatable, or when “two plus two doesn’t equal four”. This time, let’s think about when we don’t get an expected or desired outcome when we shim and move. Think of it as when “two minus two doesn’t equal zero.” You may perform an alignment measurement, […]

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Repeatability vs. Desired Outcome in Precision Shaft Alignment, Part 1

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By on October 14, 2015

When mechanics align rotating machinery, they expect two outcomes. One, they expect their alignment values to be repeatable. Two, they expect shimming and moving machinery to produce a desired outcome-namely, to be in tolerance. In this paper, we’ll discuss repeatability, which is, performing the same measurement twice, and getting the same results. If alignment results […]

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Don’t Overlook the Hold Down Bolt Washers

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By on January 22, 2015

Anyone involved in precision shaft alignment knows that unintentional movement is the biggest contributor to non-repeatable alignment results. Movement can come from several sources: Soft foot, loose bolts, flexible bases, excessive bearing clearances, improperly mounted or loose sensor mounting hardware, etc. One of the more elusive and least considered sources of movement is cupped washers […]

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Uncoupled Shaft Alignment – It Doesn’t Need To Be Difficult.

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By on October 13, 2014

The night before the OJT portion of a recent Fixturlaser GO Pro Training class, at a Combined Cycle Power Plant, the shim packs of the disc type coupling between a 3300 HP electric motor and fluid drive began to fail. The machine was shut down before any damage could occur and was waiting for our […]

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Coupling Alignment Tolerances vs. Shaft Alignment Tolerances

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By on October 8, 2014

A coupling alignment tolerance and a shaft alignment tolerance are different things – VERY different things! A Coupling Alignment Tolerance is often (but not always) the maximum amount of misalignment the coupling will operate at before premature failure. A Shaft Alignment Tolerance is the maximum amount of misalignment the shafts can tolerate before they begin […]

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Mechanical Seal Basics

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By on September 17, 2014

After completing a recent training class, I had opportunity to ask our customer what were some of the highest cost failures they experienced. The answer? Mechanical seal failures. Mechanical seals come in a wide variety of configurations and manufacturers. The cost of these seals can range from $1000 to $3000 per inch of shaft diameter. […]

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How to Perform a Precision Alignment When Nearby Machines Are Vibrating.

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By on August 6, 2014

Equipment rooms can sometimes have numerous machines running all at once-side by side.  Often, technicians are required to perform a precision alignment next to a machine which is running.  The technicians are right to be concerned about vibration from nearby machines, but the concern can be greatly reduced if certain procedures are followed. The first […]

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Using a Laser Shaft Alignment System to Check for Pipe Strain

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By on July 7, 2014

Pipe strain is a relatively common problem seen in pump installations. It is a cause of premature bearing and seal failure. Here is a link to an excellent article from Pumps and Systems magazine that discusses the detrimental effects of pump strain. http://www.pump-zone.com/topics/seals/how-do-plant-pipe-strain-problems-affect-my-pumping-systems You can easily measure the effects of pipe strain using dial indicators […]

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Coupling Tolerances

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By on April 17, 2014

There is an ongoing debate on what tolerances are acceptable when aligning your rotating equipment. The debate falls on the “published tolerances” provided by the coupling manufacturers and the tolerances “recommended” by alignment equipment companies, reliability associations and rotating equipment OEM’s. The offset and angularity tolerances are much more permissive from the coupling manufactures than […]

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Can Precision Shaft Alignment Be Too Good?

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By on April 3, 2014

A shaft alignment tolerance is simply that – an allowable, minimal amount of misalignment.  There are many different tolerance tables for shaft alignment.  At VibrAlign, we have a good alignment tolerance, based on many years of experience and engineering.  Other alignment tools have their own tolerance tables.  Many technical and trade organizations have their alignment […]

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Converting Laser Alignment System Readings to Rim and Face Dial Readings

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By on January 29, 2014

VibrAlign released the free Laser-Dials App to aid laser system users who need/want to convert their laser shaft alignment system results to rim and face dial indicator readings. You can also use the App to convert dial indicator readings to laser readings. Most are interested in converting laser results to dials so that is what […]

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How to convert angularity in mils/inch to angles in degrees

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By on January 9, 2014

Occasionally we get asked how to convert shaft alignment angularity values expressed as mils (thousandths) per inch to degrees. Since mils per inch is the rise over run that means that the conversion to an angle is the arctangent. Or the conversion from an angle is the tangent of that angle. Remember to include the […]

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