Electronics > Projects, Designs, and Technical Stuff
[advice] Crimp butt connectors for thin wire (~ 0.6 mm dia)
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Monkeh:

--- Quote from: IDEngineer on March 20, 2020, 12:08:57 am ---
--- Quote from: Monkeh on March 19, 2020, 11:51:07 pm ---Watercraft are far from the only high vibration environment.
--- End quote ---
Agreed, but marine is the only environment I regularly work in where there is an actual RULE about soldered vs. crimped connections. And the OP's environment doesn't sound like high vibration from the info provided.


--- Quote ---What, exactly, about a crimp is going to deteriorate and make it less suitable than solder?
--- End quote ---
We design and manufacture sensors for the marine industry. As a result, we do a lot of R&D in new and existing boats. I long ago lost count of the number of crimped connections we've found loose, dangling, or otherwise disconnected on existing boats. We're talking many, many, many dozens of such broken crimp connections. Usually one of the two wires wiggles free from the crimp itself, leaving the two ends hanging or (worse) lying on the bottom of the hull, potentially exposed to fluids that accumulate there (including water, fuel, and oil).

I suspect what happens in many cases is that the additional mass of the crimp itself "jerks" down on the wires during normal watercraft operation. We regularly measure 2-3G shocks on the Z axis from the hull hitting chop, and the crimp experiences that over and over during years of operation. This is the mechanical equivalent of someone yanking on the wires, which over time can lead to one of them pulling out of the crimp.

Never once have I seen a "broken" solder connection on a watercraft. I've seen plenty that weren't properly strain relieved, but none that were broken.

My solution in such cases is to discard the crimp, solder and heat shrink the connection, and then mechanically support and strain relieve it. This complies with A-11. AYBC *prefers* crimps but allows properly supported soldered connections, as I quoted above. The result is much more reliable than a crimped connection, IMHO. Granted you could get additional reliability out of a crimp by strain relieving it too, but since the spec doesn't require that nobody does it, with the long-term results as described.

The funny part is that the watercraft owners/operators often say something like "Yeah, that stopped working a long time ago but we never figured out why." These crimps are often buried behind bulkheads where they are not readily inspectable. Such connections should be made as permanent as possible (such as the technique I described above) on the presumption that no one may ever view them again.

--- End quote ---

 :palm:

Do you have anything to add outside a very specific example of incorrectly used materials?

Putting aside inane solder vs crimp discussion:
Small butt-crimps, insulated or not, would be perfectly adequate, as would the gel-filled crimps generally used for phone wiring. Done properly and secured into the wall, they'll outlast the wire. If you're going to bury them in plaster you'll need to take measures to keep moisture out so it doesn't corrode the wire.
mark03:

--- Quote from: IDEngineer on March 19, 2020, 10:57:03 pm ---
--- Quote from: viperidae on March 19, 2020, 10:50:48 pm ---Solder vs crimping is as bad as the tabs vs spaces when it comes to software dev.
--- End quote ---
Nah, there's no legitimate dispute between tabs vs. spaces. Tabs are always and everywhere a better choice. Smaller files, faster parsing, allows the user's own tab setting to generate their preferred on-screen appearance, the list is endless.

--- End quote ---
Awww man, the first one to give a categorical answer and it should have had a 50/50 chance of being right, or better, since the correct answer is totally obvious to any reasonable person!!  But of course you picked the wrong answer  >:D  :box:
IDEngineer:

--- Quote from: Monkeh on March 20, 2020, 12:18:29 am ---Small butt-crimps, insulated or not, would be perfectly adequate... Done properly and secured into the wall, they'll outlast the wire.
--- End quote ---
...or in other words, crimps should not have strain, just as I said.

Thank you.
IDEngineer:

--- Quote from: mark03 on March 20, 2020, 12:24:13 am ---...the correct answer is totally obvious to any reasonable person...
--- End quote ---
I completely agree. The answer IS obvious.   >:D :horse: :popcorn:

EDIT: Don't get me started on the boneheaded nightmare of Python's non-delimited, indent-sensitive code blocking. Whoever thought that up should beg on their knees for forgiveness before Knuth's statue.
thm_w:

--- Quote from: IDEngineer on March 20, 2020, 12:08:57 am ---We design and manufacture sensors for the marine industry. As a result, we do a lot of R&D in new and existing boats. I long ago lost count of the number of crimped connections we've found loose, dangling, or otherwise disconnected on existing boats. We're talking many, many, many dozens of such broken crimp connections. Usually one of the two wires wiggles free from the crimp itself, leaving the two ends hanging or (worse) lying on the bottom of the hull, potentially exposed to fluids that accumulate there (including water, fuel, and oil).

--- End quote ---

Wouldn't that indicate an improperly crimped connection?
If the connection is intended to be permanent, maybe a ferrule crimp and glue lined heatshrink over top (basically the dolphin item linked above). You might be using that but its not clear.

https://nepp.nasa.gov/files/27631/NSTD87394A.pdf
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