Recent content by indoldrums

Still collecting data and I plan on sharing what we find out. Will be back with more info.

amanuensis, what are your thoughts? I would like to hear your take on this. Also, just a general question; when I look at a velocity vs. frequency plot along with the bode plot from a hammer test, is it fair to say that for a frequency to be a resonant one, there must be a 180deg phase change?

I double checked the isolation pad deflections for the test setup that produced the vibration plot above, and found out that the average deflection for all four pads was 0.065in. IRstuff, when we tested the system with the stiffer isolation pads, which have the lower deflection I was thinking of...

Well, this is embarrassing because I mislabeled the axial and vertical plots. The green curve is the vertical (incorrectly labeled as axial on this chart) and the red curve is axial (incorrectly labeled as vertical). Sorry for the confusion. Also, the Base V plot is the vibration on the base...

Hi Tmoose, I don't have access to the machine right this moment for pictures but I can briefly explain the setup: The motor is bolted to the rotary compressor with a steel adapter piece. There are four isolation pads, two on the compressor and two on the motor side. This entire assembly is then...

Hi Greg, Thanks for your feedback. I would like to invest some time into this problem and do it right and learn something in the process. I am attaching the plot we took at the NDE motor foot. We have a pretty good match with the bump test results and this coast-down plot. This tells me that my...

Walter, You are correct. I have some data, and an idea of what the problem is but I think I need to investigate more in order to come up with the right corrective action. In this case, the motor is tied to the isolation pads and the isolation pads are tied to the steel frame which sits on the...

Let me try to elaborate more. We are measuring the vibration on the NDE motor foot. We are also measuring the base skid that the drivetrain is attached to, near the NDE. Base skid vibrations are not nearly as high as the motor foot vibrations. This makes me think that isopads are doing their...

Yes, it is. In fact, we tried varying stiffnesses of isolation pads but the vertical vibration amplitude wasn't affected.

Hello all, We are trying to troubleshoot a vibration issue with our motor-compressor drivetrain. The issue is that when we run a coast-down from 3600rpm down to the min speed, we get high amplitdue vertical vibrations (7mm/s RMS) at about 1500rpm and 2400rpm. Horizontal and axial vibration...

We have a sheet metal part with small [.125"dia]dimpled/extruded holes for thread engagement. We have a true position tolerance but our tooling engineers do not think that an irregular hole like this cannot be measured accurately and should not be given a true position tolerance. What do you...