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electricpete

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Reply with quote  #1 
The video below has slow-motion video (960 frames per second) of a 900 rpm coupling (the slow-motion doesn't start until 15 seconds in).

https://drive.google.com/open?id=1kirZleUjFbqrb5JymaC4QulIx-D4uY4a

This particular video was shot on my new Samsung S9+, but I understand other phones have similar capabilities.  It came out pretty good, considering the lighting was very bad. 

If I had my choice I think I'd rather have a strobe for quickly looking at something (rather than recording and then playing back), but the cell phone slow-mo video is handy if you don't have a strobe with you, and also would be handy if you wanted to show someone what you saw with a strobe.  

I might try it on belts next...see how well it shoots through that belt guard mesh which make strobing kind of difficult.    Also gotta try it on faster machines (may not work as well). 

Danny Harvey

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Reply with quote  #2 
Nice. Is that the one with the screen that goes around the edges?  I'm scared to get one of those.

I guess because it's a camera, it's not tunable?
RustyCas

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Reply with quote  #3 
So Pete, what are we seeing exactly?  And where the heck is the coupling guard? [wink]  

Does anyone know of a good way to actually take a video of a strobe light analysis?  I've tried it with my pocket camera with mixed results.  I know there are frame rate considerations.  I'm going to try it with a 444 strobe to see if that makes a difference.

I have also asked the motion amplification folks if their system will work with a "rotating" object and they seemed to sort of think so, but I've seen no examples.  I'd like to see it show a bent shaft, coupling hub wobble, coupling element wallowing around, or a shaft orbiting in a worn out bearing.... something you can't actually see or feel like you can the stationary stuff they are showing video of. 



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Shurafa

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Reply with quote  #4 
Pete,

Interesting.

A few years ago, I had a case of a level switch failing due to resonance vibration. The switch was basically a long thin rid (~ 20 in long, ~ 1/4 in dia) suspended from the top by a ceramic isolator. I had no way to measure its natural frequency except using video camera with high a frame per minute rate. The video was taken in a shop after the rod was mounted similar to its operating setup. The video is regular but using a computer slow motion software and counting the oscillating moves, the natural frequency was found. The results were very close to the theoretical (calculated) results and the measurements on the field (on the switch case). The video was an excellent support to convince the people here on the cause of the problem
(resonance).

I think this concept should be mixed with MA to have a more powerful tool.

Regards- Ali M. Al-Shurafa
diederib

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Reply with quote  #5 
We use cell phones fairly regularly in slow motion video mode. We've found that it works very well on our cooling tower fans. The fans aren't strobable due to only having one eye hole to look through, but you can place the phone to the shroud hole and take a video. We've found leading edge blade delaminations, driveshafts that are ready to fail, blade angle issues, etc. 

The nice part is that it's free and easy to do. Video can be a powerful way to impress the severity of the problem to management. Video doesn't always work, but it's one more tool in the toolbox.


John from PA

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Reply with quote  #6 
Don't forget the audio recording capability of smart phones as well.  A few years back a facility wanted to hire someone from our organization on a potential high speed gearbox problem. The gear had no instrumentation so the price was relatively high.  I had them record the airborne sound which exhibited a very regular "thump".  Comparison to an online signal generator supported that is was at gear rotational frequency (30 Hz).  I told them they likely had one or more broken teeth.  On examination through the inspection cover this was found to be the case.  A new gearset was made and they were back in business in just a few weeks.   
RustyCas

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Reply with quote  #7 
Great tips guys!

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Curran919

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Reply with quote  #8 
Quote:
Originally Posted by electricpete
The video below has slow-motion video (960 frames per second)
This particular video was shot on my new Samsung S9+


Holy hell, I didn't realize flagship phones were getting that kind of FPS already. When I was looking at phones about 1.5 years ago, the highest I could find was 120 FPS for android, and I believe 240 for apple. Those weren't very technically useful, but this is fantastic.
Danny Harvey

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Reply with quote  #9 
Pete,

When I first saw this, I had the audio muted. This evening, I showed it to my wife because we are thinking about new phones and she said you need to change those bearings.  I hope somebody is on that.[wink]
electricpete

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Reply with quote  #10 
Sorry, I've been busy lately. Lots of interesting comments.  

By the way, the recording is from the machine described in this thread: 
http://www.machineryanalysis.org/post/gear-pump-increasing-acceleration-peakvue-9768128?pid=1304536130

We have taken it out of service, but will be a long time before we get into it to see what's going on.  

Danny - I knew you had indoctrinated your son into the business, but your wife!?!  Wow, my wife doesn't even know what a bearing is, never mind what a bad bearing sounds like. 




Danny Harvey

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Reply with quote  #11 
My wife could probably pass a Category 1 test. She could also design conveyors and power transmission systems.  We drive everywhere we go so she can either listen or jump.
Noknroll

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Reply with quote  #12 
Quote:
 We drive everywhere we go so she can either listen or jump.

Thanks Danny
I gut a chuckle out of that
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