Is checking shaft runout part of everyone's standard preparation when performing a shaft alignment on machines running OK?

Thanks,

Dan T

If you're fixin' something that ain't broke, how good do you fix it?
Really, if a machine is worth aligning, it is worth aligning right. Checking runout is a basic part of alignment. At the very least, pry up on the shafts, and estimate the runout. If you see movement, measure it.

Sorry for the short answer above. Of course, there are many kinds of alignment. Some may not deserve checking runout, while others may need very precise measurements.
At our mill, we do not normally check alignment on machines that appear in every way to be 'running OK'.

Dan,

I don't do it on every one. If there was a train wreck or some other reason to suspect a bent shaft or similiar situation, I check it.
If it is just putting a new or rebuilt motor onto something, I don't check it, but I guess I would if I was having trouble getting it aligned and soft foot wasn't the cause.

Dave

quote:

when performing a shaft alignment on machines running OK?

Dan - If a machine is running OK, then why bother to do an alignment check??
If someone decides to take the time to perform an alignment, then there was a reason to do so.
I always check runout. It is easy to do and is one less thing to consider if procedure isnt going well -----and I've had quite a few :-)

At my work, part of my job is to train Navy and Crafts personnel to perform a proper alignment. I have a step by step procedure that I insist they follow and document (TIR, soft foot, clean surfaces, etc.) In my experience, a good alignment procedure will require 60% to 70% prep time and 30% actual move time.

In addition: 'not just shaft runout'! As Dave pointed out a pump sitting and a new motor installation - in all probability the shaft is OK if there's any kind of QA at the shop. However, that is not always true for couplings and their bore as I've seen many bored askew or missed concentric centerline by 8 mils and it gets into the field for a 'new' application. It should be checked.

Having records is always and history with that record is great. Seal failures before bearing failure; seal failure with bearing failure are indicators that lead to further insight to a machine's failure root cause.

By runout I meant shaft mechanical straightness, checked with dial indicator while rotating the machine's shaft. Yes, either an out-of-round or non-concentric reference diameter would contaminate the runout measurement.

Methods and hardware that rotate both machines' shafts together (typical indicator reverse, laser) use the rotating shaft centerline as the reference, and ignore stuff like shaft runout and coupling hub runout. That's an advantage most of the time, since Sweeping a stationary coupling hub OD means I'm really aligning to that hub OD. In that case the chances are low that the resulting SHAFT alignment is really within 0.002 inch of where I think it is. Lots of folks here think aligments not within 0.001 inch are unacceptable.

Googling shaft alignment and laignment procedures took me all over the place. Here is a list of on-line precedures, grouped by whether they specifically mention shaft runout checks or not.
I was a little surprised the factory compressor (Frick and FES) procedures have you practically toss the alignment brackets right on the shafts.

runout check
http://www.alinemfg.com/procedure.htm
http://www.reliabilitydirect.com/alignmentproducts/Dial...ator%20Procedure.htm
http://www.turvac.com/HTMLs/shalhandbook.htm
http://www.maintenanceresources.com/referencelibrary/alignment/importance.htm
http://www.osbornetrainingservices.com/index.asp?pg=51
http://www.fixturlaser.com/?id=933

no runut check mentioned
http://www.reliabilityweb.com/excerpts/excerpts/shaft_alignment_procedure.pdf
http://www.pdmsa.com/Frickalignment.pdf
http://www.pdmsa.com/FESalignment.pdf

unclear
http://www.withinspec.com/products/tr_dial.html
http://www.newlearningcenter.pwpl.com/catalog/viewprod....eptID=33&prodID=6549

Dial indicator checks for shaft/coupling runout should always be performed unless there is a good reason that it can not be performed. By spending 1-2 minutes checking your runout you can save a lot of headaches after start-up by finding bent shafts, couplings not centered or seated correctly.
We have had quite a few problems with high vibs after a motor or pump relacement that would have been caught by doing this quick runout check. We are seeing more and more couplings having excessive clearance in the fits of the drop-outs causing high vibs after repairs.
So many mechanics these days simply do not know how to use dial indicators, they rely on laser alignment and do not realize the value of using the indicator along with the laser.

More to consider or food for thought or how I've been getting the shaft; or is that shafted!

Let's say you have a motor and pump rather large and its or their coupling type and shaft design allows for much extension from housing to coupling hub.

Check shaft runout near the housing and then near the coupling hub. Check coupling hub both radial and axial. The rule of thumb I use is 2 mil max runout with a stack tolerance of 3 mil. Document all!

Need more: picksam@juno.com have tolerance charts, etc... For the chart below as it appears in Word - write and ask.

ALIGNMENT PROCEDURES

þSAFETY; lockout and tag. Rack out fuses and chain valves when necessary

þEnsure that the driven machine has no stress from piping if connected or soft foot and that the anchor bolts are tight

þInspect the feet and base of the machine to be aligned for burrs, roughness, dirt

þEvaluate if a temporary spacer is need or useful for this alignment process; note

þInspect coupling and check for run outs – all run outs.

þCoupling halves should rotate together if possible for dynamic alignment

þEvaluate which method of alignment should be used

þWhich alignment method is best suited for this job; __________________

þIs axial thrusting a factor: ______________

þRough align within 1/16 inch

þCollect SAG data and record (calibrate – laser and/or indicators)

þInstall brackets on machines and record machine dimensions

þCheck for soft foot; correct as necessary
þRecord alignment readings

þAre they valid? Mathematically correct and repeat?s thrust a consideration?

þCalculate shim and lateral shift change
þVia computer? Print and file?

þCalculator? Record, plot and file?

þMake changes and verify & RECORD

þIf spacer was used, remove at this time

þPLOT THE FINAL ALIGNMENT DATA

þUNLOCK AND REMOVE TAGS; NOTIFY OPERATIONS

þPLACE RECORD AND PLOTS IN MAINTENANCE FILE

REMEMBER; IF YOU ARE USING A LASER - CHECK CALIBRATION. IF DIAL INDICATORS - CHECK SAG. USING A LEVEL - CHECK CALIBRATION; ETC... ETC... AND OF COURSE ETC...........