April 11, 2012
By Chris Troutt
Not too long ago I was called to one of our sister shops to perform a laser shaft alignment on a 3600 RPM skid-mounted end-suction ANSI pump. Easy, right? Honestly, I made a few mistakes right off the bat:
- Thinking this would be easy (and starting right before quitting time).
- Taking for granted that all surfaces had been properly cleaned and inspected.
- Not doing all the steps that I have been taught and the same steps I teach our techs.
- Not asking why it was in for repair.
I performed a quick pre-alignment, mounted the equipment and took a reading. The motor needed to come down over 200 mils and move horizontally 406 mils. I wasn’t expecting that. So we took another set of readings with the same results. A quick look at the coupling did not show it being off this much.
So I stepped back and thought…..”What am I missing?”
I wanted to ensure we did not have a laser issue, so we mounted the laser alignment equipment to a piece of stock in a lathe and took some readings. All repeated, three times in succession, so no laser issue! I inspected the shaft and coupling run outs, and did a thorough visual inspection of the entire unit. I pulled the pump off the base, cleaned rust from the base feet, scrapped off a coating on the base, and did the same to the motor. Next I removed both the couplings, looked for burs/dings on the fits, faces and bores. Ensured a slip fit on all coupling hubs, key-ways, and bores. Then I replaced all bolts with new hardened bolts and flat washers – no lock washers! I did soft foot checks on both motor and pump uncoupled from each other, and did find some in the pump. I tightened everything down using a three-pass method, did a final soft foot check, and started a fresh alignment.
This alignment check indicated the motor was 101 high in the front and 103 high in the back, and the horizontal was out 45 in the front and 98 in the back. I made all corrections in about 15 minutes, with one spin of the shaft. Final readings were well within a 3600 spec!
Lessons of the day…
- Always check for yourself. Your idea of “ready for alignment” may not be everyone else’s.
- Don’t overlook all the alignment steps, sometimes it takes a little more than a couple soft foot checks and a torquing sequence to get an alignment to go well.
- After seeing the old coupling, I knew why it was in for repair! It had worn off the original teeth and had cut new ones 3/8″ below where they should have been. This thing had serious trouble in its alignment!
- Here is the biggie! Don’t let it get you frustrated; back up, take a breath, and cover the basics we all know. Most of the problems we see can be eliminated through simple fixes.
I am not sure what part of my “basics” check list eliminated my trouble spot, but through all of that I got the bad actor out of it!
From VibrAlign – Special thanks to Chris Troutt, Reliability Analyst at BRI (a Cogent Company based in St. Louis, MO) for a great blog post! We want to encourage any of our readers to post comments, questions, case histories and ideas to the blog. We’d love to hear what you have to say!
Based on my 7 year experience in machinery ,I strongly believe we indemnify because we overlook preliminary things. That is, we consume our time and money because of overlooking primary checking like cleaning ,soft foot ,run out and so on.
As I always tell my customers….the fastest way to do an alignment is to take your time! Great blog post Chris and thank you for your input.
I noticed from the picture of the machine that the motor had no jack bolts. Can I ask what you used?
Nice job Chris! Work slow to work fast.
We used a small dead blow to make the horizontal corrections. Unfortunately, this set up like a lot of them had no jacking bolts. With a clean base and new shims the motor moved very easily. For the record I do prefer jack bolts.
First, my thanks to Chris for authoring this post.
Secondly, this is so on target! Shaft alignment doesnt need to be difficult. Technique is really important. When we behave in a repeatable way, we get repeatable results.
Lastly, I truly enjoy this blog. I only wish more people would participate.
Comments, questions and examples are truly welcome. If you have a question or want us to write about a specific topic, please make a comment on any post.
Do you think it is advantageous to take the time to mount your own jack bolts? I have an idea that within an hour can have all four jack bolts mounted. What do you think? Kevin
In some cases on which the motor is not heavy,we have NO jacking bolts.We are using a light hammer to move the motor for horizontal direction.
Thank you so very much.
I very much would like to have your idea and hope we would be able to integrate to our base frame.I think the structure of all base frames are not the same and we may not be able to have your idea with existing base.
My idea involves 4 pieces of 4 inch angle iron with mounting holes for the floor or side of machine to be aligned. A slot is machined in one side of the angle for vertical adjustment. One inch thick spacer blocks are made to accommodate the height differences to motor feet. In an hour you can drill and tap holes in side of motor mounting base or drill and install tapped plugs into the cement. After the alignment is complete you can screw set screws into the plugs you put in floor enabling future use of them. All pieces used in the alignment can be used in future alignments except the plugs placed in the cement. I am a machinist/toolmaker by trade, so if I don’t have to use a hammer, this is what I prefer to do.
Kevin–I like the idea. Certainly sounds robust enough for the bigger stuff. There’s a picture of a different style here–http://www.thealignmentblog.com/2011/07/jacking-bolts/. Stan also drew up some in this post–http://www.thealignmentblog.com/2011/12/jacking-bolts-for-shaft-alignment/. Different ways to skin the proverbial cat.
I think the important thing is controlling the moves. Sometimes a mallet will do fine but being able to ‘dial it in’ with jacking bolts can save enough time ( and frustration) to make it worth the effort of installing them. I’ll keep an eye out for nifty ideas in the field and post them here.
Thanks for taking the time to submit this post. Posts like this really remind us how important the prealignment steps are. Nice to see you contribute.
Kevin, I like your idea. I’ve made some similar myself. Like you, my background is machinist/toolmaker. I believe that, in many instances, the time taken to rig up some jackbolts can be recouped in the time saved by aligning.
Not always, but sometimes.
Either way, it beats all of the hammer marks on the motor!