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A few weeks ago, I was at an engine manufacturing facility, training the technicians on using our ROTALIGN ULTRA IS Laser Alignment System. They were using it to align their engines for proper testing. To begin, the technicians rough-align the engine. To test the engine, they couple it to a gearbox with a 5-foot long spacer coupling. They set up the laser and receiver at 12 o’clock and then turn the shafts clockwise, using Continuous Sweep mode. In one instance, at about 45 degrees of rotation they ran out of measurement range. Due to a combination of the longer separation between laser and receiver, the large misalignment and the small amount of rotation, they were not able to achieve good repeatability.
So I suggested the following solutions:
First, I recommended zeroing the laser at the 12 o’clock position but to start the measurement at around the 10 o’clock position and rotate clockwise. They were able to achieve a rotation of about 85 degrees and obtain great repeatability. The customer’s comment was “We are used to start the measurements at the 12 o’clock position from old dial indicator practices”. It may be convenient to zero the laser in the 12 o’clock position, but you can start taking readings at any rotational position, even with the beam at the edge of the detector range. This way you can maximize the measurement range of your laser alignment system.
Secondly, I suggested that they zero the laser at 12 o’clock and start rotating the shafts while observing on the computer screen in which direction the laser beam is moves on the detector. Stop the shafts and readjust the laser beam as far as possible in the opposite direction to the observed movement. Start taking readings in that position, and again this will maximize the measurement range of the detector and consequently also increase the amount of shaft rotation you can get before running out of range. If you can achieve at least 70 degrees of rotation, you will obtain accurate readings.
I also made a third suggestion: If the misalignment is so bad that you cannot obtain 70 degrees of shaft rotation before you run out of measurement range, no matter how far you initially adjust the beam in the opposite direction to its track, then use “InfiniRange”. This feature is available in the Multipoint measure mode and lets you stop to readjust the beam while taking readings, as often as necessary in order to achieve the necessary rotation to get good readings.
So, keep these ideas in mind and no amount of misalignment will ever stymie you in the field again!

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by Adam Stredel CRL