quote:

Originally posted by Sam Pickens:
Generally we do not know where the machines will go when in the hot and running position under load.

Having a realistic set of tolerances is most deserible. Shooting for 'zero' is basically not practicle.

Normally built-in tolerances are not adequate (too loose). I use a tight set of tolerances that I think I can safely say are tighter than anyone's in the industry. But you can still do one-shot alignment using proper procedures and techinques.

The OEM specs are generally good but use the machine's component whose tolerance is tightest; ergo, a mechanical seal. Coupling OEM's specs are generally very loose.

Check me out in 'For Sale' items as there may be an item of interest; but look at the attachment.


Always apply common sense. Does the machine dictate "hot alignment" to be performed?

quote:

Originally posted by Rockin' Rod:
Hi Sam,

I want to enlarge on this hot alignment if I can. About three weeks ago we were told to use a blower startup check list, and document the blower alignment, BEFORE start up, for warranty purposes.

We used the OEM alignment procedure and formula to compensate for thermal growth. We added shims to just the motor, none under the blower, as per the instructions...We also had to show them the alignment report so they could sign off on it.

Here was the problem. They recommended running the machine 3 hours, then checking the hot alignment, but after shutting down the machine and then attaching the laser, all the readings changed. We tried to hurry as fast as we could to get accurate readings but found this to be impossible.

After contacting the blower company, they clarified that, "no, we meant we wanted the alignment numbers after the cold alignment with"...

So basically once we get the temp differential and throw the formula in there, and add the shims to the motor, or take out, depending on where the outlet is, that's all we could do...

I'd be interested to see what some of you do...There are two attachments to alignment I'll post

Thanks,

quote:

Originally posted by Sam Pickens:
Generally we do not know where the machines will go when in the hot and running position under load.

Having a realistic set of tolerances is most deserible. Shooting for 'zero' is basically not practicle.

Normally built-in tolerances are not adequate (too loose). I use a tight set of tolerances that I think I can safely say are tighter than anyone's in the industry. But you can still do one-shot alignment using proper procedures and techinques.

The OEM specs are generally good but use the machine's component whose tolerance is tightest; ergo, a mechanical seal. Coupling OEM's specs are generally very loose.

Check me out in 'For Sale' items as there may be an item of interest; but look at the attachment.


Always apply common sense. Does the machine dictate "hot alignment" to be performed?

quote:

Originally posted by RRS_Dave:
Rod,

When I do hot alignment, I have all my ducks in a row before killing and locking out. I may even loosen guard bolts, etc. to get a jump on it. After removing guard, do a "quick check". Don't worry about putting in measurements of receiver to center of cplng., etc. Take a couple of readings first thing. Then put the measurements in.
Now, average the two readings you just took. Do what the correction says. That is all you can do at this time.
If it is 3600 RPM, and critical. Start it back up for an hour, then repeat the above process.
As you saw on your laser, as soon as you shut down, things start cooling off (or heating back up in the case of chiller compressors, etc.) and are forever changing. You can't keep up with it. All you can do is catch it at a point, and make the corrections called for. Again, if it is real critical, do it again after warming(or cooling) machine again.

I generally do the vertical correction called for first, then turn the laser back on and go "live" to get horizontal. The horizontal does not change as dramatically (as a rule) as the vertical does. You can usually align it right back to where it needs to be.

Dave

quote:

Originally posted by Rockin' Rod:
We did the same thing here Dave...What we ended up doing was installing the recommended shims under the motor feet, as per the formula, and blower manual.

I just referred back to the vibration readings I took on that day. All the readings were well below the maximum allowed, which was .280 ips, Bearing temps were only 164 after 3 hours running time...

There are two different notations in the blower manual concering hot alignment, heres the first.
********************************************

quote:

Originally posted by RRS_Dave:
Rod,

When I do hot alignment, I have all my ducks in a row before killing and locking out. I may even loosen guard bolts, etc. to get a jump on it. After removing guard, do a "quick check". Don't worry about putting in measurements of receiver to center of cplng., etc. Take a couple of readings first thing. Then put the measurements in.
Now, average the two readings you just took. Do what the correction says. That is all you can do at this time.
If it is 3600 RPM, and critical. Start it back up for an hour, then repeat the above process.
As you saw on your laser, as soon as you shut down, things start cooling off (or heating back up in the case of chiller compressors, etc.) and are forever changing. You can't keep up with it. All you can do is catch it at a point, and make the corrections called for. Again, if it is real critical, do it again after warming(or cooling) machine again.

I generally do the vertical correction called for first, then turn the laser back on and go "live" to get horizontal. The horizontal does not change as dramatically (as a rule) as the vertical does. You can usually align it right back to where it needs to be.

Dave

quote:

Basically jumping on something once it is shut-down is not hot alignment in a true sense.