vibration, music, and loose screws

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Dan Daniel

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I have fixed up some cameras over the years and sold them. This has almost always gone well with no returns or complaints.

I just collected a Minolta Autocord that someone bought a couple of years ago. The shutter wasn't cocking properly. When I opened it up I noticed that the screws holding the lens board to the focusing helical were loose, and the grub screw for securing the viewing lens was very loose.

I contacted the owner and asked about motorcycles, bicyles, planes. She says that she uses the camera at concerts all the time. She's in her 20s, and I expect that this means lots of heavy bass.

Anyone have a camera rattled loose by music?

And any suggestions to prevent this? I usually put a very light coat of grease on threads before assembly, a vestige from my bicycle mechanic work where this allows for secure tightening.

I'm thinking that I should use medium strength thread locker this time around. Just the lightest drop on the screws. Any problem with this?

Thanks- Dan
 
Depending on the size of the screws, I'd be careful about medium thread locker. It still requires considerable torque to break loose, and on small screws the heads might strip first. I like clear nail polish for small screws, and I've used plain old white glue as well directly on the threads, but I'm sure there are other good options. I also work on bikes, so I understand the logic of greasing threads, but I tend to prefer something that will dry to help retain the small screws usually found in cameras; a big part of the rationale for grease on bike fasteners is to keep moisture out - this is less of an issue for cameras in most cases.
 
Thanks for the comments and suggestions.

The use of grease on bicycles due to moisture makes sense. It does allow for proper torquing, but it's not the same situation as a camera.

The Weldbond makes a lot sense. It's a nice glue, secure with a touch of flexibility, and on this scale it will let go easily when needed.

I went ahead and used clear acrylic nail polish. Turns out that there were a LOT of screws loosened up on this camera. All of the focus helical system, viewing lens, strap lugs, door hinge, tripod plate. Even the cocking arm cam needed some serious adjustment after everything else settled into place. That's some serious sound systems the woman who owns the camera is hanging around. I wonder if she'll have any hearing by the time she's forty?
 
Okay this is interesting to me. Almost every digital camera I've owned has had at least 1 screw come loose on the baseplate. Not kidding. It's like a repeatable pattern and I couldn't figure out why. I've had an Olympus E-3, canon 5d, e-p1, eos-1n and fuji x100 all have a screw fall out of the baseplate. I do take my camera to a lot of shows, and many of them are hardcore/super loud, so it kind of makes sense....

Mind = blown.
 
First I had ever heard of this, but it does sort of make sense. But I would have thought anything that could loosen screws that much would effect lenses as well. I guess not. But I would have thought nail police would be better as it can be loosened with acetone.
 
oftheherd said:
First I had ever heard of this, but it does sort of make sense. But I would have thought anything that could loosen screws that much would effect lenses as well. I guess not. But I would have thought nail police would be better as it can be loosened with acetone.
Click to expand...

The front and back lens units of the Rokkor in the Autocord are combined units. There aren't retaining rings allowing for removing elements. There's a name I can't remember for rolling and compressing brass to make a solid unit, but this is what has been done with both sets.

Front and back lens blocks weren't loose. Maybe their size didn't resonate with the sound system waves?

I wouldn't suggest dripping acetone inside a camera. It will dissolve plastics, paint, and acrylic. Once you liquify paint or acrylic and it starts flowing into other areas you could have a real mess!
 
PKR said:
Hi Keith;


I'm guessing that your schooling wasn't strong in the sciences? This is fairly common with people who work in the arts.

See: What causes resonance? in the first citation..

http://en.wikipedia.org/wiki/Vibration

http://www.dtbtest.com/dynamics-vibration-testing.aspx?gclid=CM6hod2WqLYCFaiiPAodBQoAHA

http://www.youtube.com/watch?v=BE827gwnnk4

http://www.cascadetek.com/testing-s...ing?mfept=pt&gclid=CIXirqiWqLYCFciiPAodthkAIg

http://www.popularmechanics.com/technology/engineering/infrastructure/4335323

http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)
Click to expand...


Ahh no ... I don't doubt that this happens! But I do confess that I didn't pay a lot of attention to anything at school. 😛

It just made me think of the mythbusters episode where they explored the theory that low frequency vibration from enormous sub woofers was capable of causing spontaneous defication! 😀

It makes you wonder how many of these boneheads in their cars that 'doof doof' their way through the traffic have to constantly tighten interior fittings. 🙂
 
I think I remember a comment by Tom A who's Leica had a couple of screws vibrate loose while flying.

I usually carry my Canonet when driving the Freightliner. It sits in the passenger seat (No Bag) but it rest on my spare rain suit. I kinda worry about it sometimes.
 
 
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