One of the big problems I’ve seen people run into when doing alignments is a lack of repeatability due to high vibration from nearby machinery. It’s obviously pretty difficult to align something that’s moving several thousandths. There are still ways to get accurate readings with some laser alignment tools.

Let’s say you are in the same situation but aligning with dial indicators. The indicator needle is jumping back and forth between 35 and 42. Most likely,  you will settle for the average midpoint of 38 or 39. You can do the same with lasers.

The first thing to do would be to switch over to one of the “manual” measure modes (like Multipoint mode) rather than the fully automatic measurement modes (like Continuous Sweep or Pass Mode.) In Multipoint,  you can adjust the averaging (sampling time) for each reading and spend a little more time taking each point. A longer sampling time will allow the tool to take much more data at each measurement position and average the data together very accurately, unlike guessing as with the dials. It is also a good idea to take several positions (8 or more) around 360 degrees of rotation. While the minimum required is 5 points over 70 degrees of rotation, the more points and the more rotation you have, the better your results will be. Check your repeatability. If it’s not good, look at your Standard Deviation values. These should be very low. If they’re not, then perhaps your averaging still isn’t set high enough to overcome the surrounding vibration problems. If you can’t get repeatable numbers, spend a little more time taking readings. No one likes chasing their tail making fruitless or inaccurate corrections.

Live move can also run into some problems in high vibration scenarios. Make sure you adjust the averaging value for the Move Function to the same value with which you took successful readings. It may take longer for the results screen to update but will steady the move and greatly improve its accuracy.

The thing to keep in mind is that a good laser alignment system measures down to 1/25,000 of an inch. If the laser is moving, it will affect your readings. Just know how to overcome the problems when you run into them.

We recommend that you take a look at our Alignment Matters Repeatability Video Tutorial

Filed under:
, by Tyler Wulterkens CRL