Everything degrades with time, I know that. Yes, I can try one, but don't really want to bother and also, I have never used a strain gauge in a circuit. Do you have an opinion about whether these are still viable?

They have two dates inside the folder and both are 1970 - they're almost 50 freaking years old! I can't find information about them or the company. The actual components are still contained in cellophane. Note the spelling of "gage". [edit: which is peculiar to me but commonplace for the components even today?] Pretty neat.

 

The company is now gone... it was called Balwin-Lima-Hamilton Corp. They manufactured railroad engines... Looks like there's a protective cover on them.

Here's an interesting document written by one of their guys about high temp strain gages...

https://babel.hathitrust.org/cgi/pt?id=mdp.39015086436121;view=1up;seq=11

Here's another:
https://www.google.com/url?sa=i&sou...aw3lRmh3G-wno75Jy_hPqFb5&ust=1558537546386677


check the resistance on across them while bending:

 

I would suspect that most gauges would degrade only if they’re stressed. Since they are in original condition, they may be good. A carefully designed test would confirm. Note, a gauge designed around a compressible rubber-like compound would degrade.

 

The company is now gone... it was called Balwin-Lima-Hamilton Corp. They manufactured railroad engines... Looks like there's a protective cover on them.

Here's an interesting document written by one of their guys about high temp strain gages...

https://babel.hathitrust.org/cgi/pt?id=mdp.39015086436121;view=1up;seq=11

Here's another:
https://www.google.com/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwik48mP86ziAhWSiOAKHcrlCWAQjhx6BAgBEAI&url=http://application.wiley-vch.de/books/sample/343303138X_c01.pdf&psig=AOvVaw3lRmh3G-wno75Jy_hPqFb5&ust=1558537546386677


check the resistance on across them while bending:

Nice! Thanks.

 

I would suspect that most gauges would degrade only if they’re stressed. Since they are in original condition, they may be good. A carefully designed test would confirm. Note, a gauge designed around a compressible rubber-like compound would degrade.

Interesting. I note that, in the instructions, they talk about using DUCO mounting cement.

 

Well then.

That could be a problem. I’ve used Duco cement way way back, but can’t remember what it was based on. Wikipedia says that Duco was known for automotive lacquer finishes. They may have started a side business. And lacquer won’t last.

It’s a destructive test. But gently flexing the gauge will immediately show a problem.

 

This? I think I remember how this stuff smells and always feels light and cool

https://www.amazon.com/Duco-Cement-Multi-Purpose-Household-Glue/dp/B0000A605H

 

That’s it. If you read the description, it’s nitrocellulose based (otherwise known as guncotton, an explosive material)

Mucilage is s similar glue. Both have a limited shelf life. I would expect the glue bond will fracture if it’s that old.

That’s why I suggested a flex test. Good luck!

 

hey dj i think the glue was suggested to install this onto whatever you were trying to determine whether it was flexing or not. I would try to find a more flexible glue to install this. It is possible it was meant as a one time deal... a steam engine boiler expansion is probably destructive...

 

These are still sealed. Had they already been cemented, then @djsfantasi's comment would have been particularly notable. To clarify what I meant - here are the instructions:

 

These are still sealed. Had they already been cemented, then @djsfantasi's comment would have been particularly notable. To clarify what I meant - here are the instructions:

View attachment 177903

View attachment 177902

Ahh, yes a significant difference!

I’d use a thin layer of latex-based cement, such as E600, or even a contact cement, like Gorilla Glue Clear Grip.

 

I wonder what they use on the production strain gauges

 

I don't know...I may just eBay them (although that is a lot of trouble). They sound to me like early strain gages and I really like the old-time packaging...and now I know some of their history.

I wonder if these came about through an internal R&D project...maybe by the author of that paper @Wolframore cited....it just seems to be a waste to use them now (although I can see that one of each is missing from the package). I don't even know where I got them - probably in a box of junk when someone was cleaning out a lab and I said "hey, are you throwing these out?" I'll take them!

 

maybe save them for your museum.. you can get them for about $1 each now... play with these...
https://www.ebay.com/itm/BF350-3AA-...m28785d38fa:g:mi4AAOSw44BYSU2j&frcectupt=true

they all recommend cyanoacrylate (superglue) for mounting - about 2% strain is what they measure... the circuitry looks like wheatstone bridge used to measure resistance... makes sense.

They also have an amplifier based on LM358 for them.

 

My guess is they would work just fine. I was using straion gauges made by MM Group (Micro Measurements Group) now a part of Vishay. The ones I was using were maybe 25 to 30 years old. Depending on packaging and storage my only observation was the tiny copper pads, which you clean before use anyway, had a very light layer of corrosion on them.

BLH, I used quite a few of their load cells years ago. Many of the ones we had in use were in harsh environments and functioned just fine for decades. Good stuff.

The resistance of the ones you have is interesting. Everything I worked with was 350 or 120 Ohm I never saw a 505 Ohm.

Ron

 

I read the second link that @Wolframore posted back in #2. It is a very interesting story. If I remember, strain gages were developed in the mid 30s...BLH marketed the SR-4s in the early 40s. These are from 1970. They are early, I guess, but not so much. Nevertheless, it is a pretty cool story.

 

At one time superglue was indeed used for strain gage attachments and it worked well, but the technicians kept getting their fingers glued. That was in the era when superglue was a new product. It works well but be careful. The non-destructive check on the gages is to measure the resistance and compare it with the label. Simple and easy.

 

Bad experience with strain gauges. Project was to build an elevated insulated tank for molten resin to offload. Tank truck drives under and area operator starts loading the truck. Strain gauges on each leg/column of the tank to a weigh system in the control room with outside annunciator to alert him to turn pump off to complete the fill. Never did work. The piping to the tank acted like a torsion bar affecting the moment on the tank and making strain gauges highly inaccurate. Also the typical semi truck had a highly amplified CB radio that when broadcasting wiped out the weigh system with RF. Factory techs from the weigh system vendor spent several days on it before throwing in the towel and telling us the tank HAD to be repiped to prevent any torsion loading of the tank. The guy was driving back home to Tampa from the Georgia Coast and fell asleep in the wee hours of the night on I10 and slammed into the rear of a disabled/parked semi and died.

 

Well that could have went better, much better.

Ron

 

Bad experience with strain gauges. Project was to build an elevated insulated tank for molten resin to offload. Tank truck drives under and area operator starts loading the truck. Strain gauges on each leg/column of the tank to a weigh system in the control room with outside annunciator to alert him to turn pump off to complete the fill. Never did work. The piping to the tank acted like a torsion bar affecting the moment on the tank and making strain gauges highly inaccurate. Also the typical semi truck had a highly amplified CB radio that when broadcasting wiped out the weigh system with RF. Factory techs from the weigh system vendor spent several days on it before throwing in the towel and telling us the tank HAD to be repiped to prevent any torsion loading of the tank. The guy was driving back home to Tampa from the Georgia Coast and fell asleep in the wee hours of the night on I10 and slammed into the rear of a disabled/parked semi and died.

That was always the warning when we used any kind of weighing system, which was that the plumbing was not allowed to exert any force on the object being weighed. HBM, the one vendor of load cells and weighing systems, had a small book on the subject. And we did achieve that and met some tight accuracy specs. My company could have made a system that worked, but my advice would have been to use a level sensor on the tank. Or, re-plumbing could certainly have solved the problem, there is no way to compensate for a poorly fabricated assembly.