At times, shaft alignment can become extremely frustrating almost as if it is possessed with a mind of its own. One set of readings may indicate that you make adjustments one way, the next set of readings then indicates something completely different. Quite simply, and almost without fail, if there are repeatability issues then something is loose with the laser alignment tool or there is some mechanical play.

Assessing Detector Movement

Here are some simple questions to work through to try and diagnose and address issues with looseness:

• Are the chain brackets tight to the shaft or hub?
• Are the detectors tight to the rods?
• Are the extension rods tight to the brackets?
• Is the sensor rubbing on something when positioning the shaft?
• When using magnetic brackets, do the magnets have full contact to prevent them from slipping?
• Did you bump something out of place?

Assessing Coupling / Bearing Play

Here are some simple questions to work through to try and diagnose and address issues with mechanical looseness or play:

• Are all the hold-down bolts on all pieces of equipment tight?
• If it is mounted to a hub instead of the shaft, is the hub tight to the shaft?
• For sleeve bearings, has the shaft come to rest so you know for sure it’s in the same spot for measuring?
• Is there coupling play or backlash?
• Is there any bearing play?
• For all the above, did you double check and are you sure?

Other Diagnostic Factors to Consider

There may still be base or foot movement that is causing looseness or it could be a torsional movement issue. Simply, you will be able to tell by addressing the operation of the machine to ascertain:

• If the feet are moving relative to the base
• If the base is moving relative to the feet
• If there is debris around the shims and base
• If multiple shims can be consolidated

Torsional movement addresses looseness in the coupling, whether it is being controlled in a consistent manner if the backlash in the gearing is being controlled, and if the chain or magnetic brackets are fitted tight to the shaft or hub.

Thanks to our colleagues at BENCHMARK PDM for sharing this blog with us!

Laser Shaft Alignment Troubleshooting: Part 1 Repeatability