Well, the questions keep coming in for our Ask Greg! feature. Here’s another winner of a FREE D90 Belt Alignment System (a $680 value!) – just for sending in an alignment question!
Our question today comes from Rob Miller of Cargill in Gainesville, GA. Rob writes:
When performing a soft foot measurement using your laser system, does the system show the actual measurement at the foot or the amount the shaft deflect due to the soft foot? We struggle with getting technicians to know the difference between the two using our existing laser/indicator systems. How does yours differ and what makes for the best solution to this dilemma? Thanks, Rob
Thanks for your email and submission to the Ask Greg! blog on our website.
I think that it is important to understand that, when using any laser system to diagnose a softfoot condition, you are making some assumptions. First of all, most machine bases and/or motor feet are not flat or parallel to each other. If you have a “bent foot” or a tapered base (which is usually the case,) laser systems will not detect it. The best way is the tried and true feeler gage or precut shim to sense the taper and shim correction thickness.
It is also important for technicians to understand what is going on when using a laser system and what information are you getting when you loosen the hold-down bolts on a motor. The Easy-Laser program shows the relationship of all 4 feet; this gives you a picture of the “plane” that is created instead of simply creating a correction value. Getting a number is handy, but can actually be misleading if the technician doesn’t understand what the value means, or what conditions may be present. A dial indicator positioned on the machine foot will record a value when the foot is loosened; the laser mounted on the shaft will record shaft deflection. Assuming the feet and base are parallel, both methods will give you a set of 4 values that you can work with to correct the softfoot. Look for the “plane” (3 values that are within .002” of each other) and subtract that average from the high number. That’s the correction or shim pack to place under the foot.
F1 = 3
F2 = 4
F3 = 5
F4 = 14
The average of the 3 similar feet is 4 (3+4+5 = 12; 12 / 3 = 4). Therefore, the correction value is 10 to be at the same plane (14 – 4 = 10).
Now, with dial indicators, you are getting the same results, but usually through different values.
F1 = 7
F2 = 8
F3 = 9
F4 = 18
The average of the 3 similar feet is 8 (7+8+9 = 24; 24/3 = 8). Similarly, the correction value is 10 to be at the same plane (18 – 8 = 10).
We find that when it comes to addressing soft foot, making sure your technicians understand the dynamics of what’s going on can make all the difference towards beginning a successful alignment.
Thanks for your question and please feel free to visit our site for more resources, or call us with any questions.
Thanks for your question, Rob – you can expect to see your FREE D90 in the next couple of weeks!
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