Crimping two wires together on the same crimp-connector it's criminal?

Marcus2012

Joined Feb 22, 2015
403
Well being I rarely follow standard convention wherever possible I crimp and solder followed by having the wire itself properly supported near the connector so that it can't wiggle or flex.
This is the important thing I think, stress relief on the cable. While I'm not sure about rules/protocol regarding two wires etc. I'm pretty sure it is a requirement in aerospace that all crimped connectors have stress relief as to mitigate the risk of connection failure due to mechanical stresses.
 

#12

Joined Nov 30, 2010
18,223
aerospace and submarines have internal rules prohibiting the 2-wire technique in most situations.
1) Probably to keep the job requirements within the capabilities of the workers.:rolleyes:
2) They probably don't try to put 7 ring connectors on one motorcycle battery terminal.:eek:
There just isn't enough room to Mil-spec every wiring job. When I don't have a calibrated crimper that will mash steel and room to put in service loops, I go for second best: reliability.;)
 

Thread Starter

gimpo

Joined Jan 27, 2016
124
I've never seen a crimped connection soldered as well.
When I was young (!) almost every installer of audio HI-FI components for cars was soldering after crimping. I don't know if this habit is lost nowdays, but I suspect is not.

I guess it doesn't hurt much if you can deal with the loss in bend radius due to solder flowing up inside the wire.
Yes, I think that stranded wires (cause of their internal structure) can allow micro-stretching whatever they are soldered or crimped. So I don't understand the point of AnalogKid about the military requirements... for sure it's my own limitation...
 

GopherT

Joined Nov 23, 2012
8,012
I'm sure that those two links are ironic :p:D
They work great. Just add silicone to each end before pressing and slide a piece of heat shrink over the whole thing. If you don't like it, peck another method.

How many amps are you looking to split off.
 

tcmtech

Joined Nov 4, 2013
2,867
I have a Hammer Crimper for doing stuff over 10 ga.
SAme as this one.
http://www.amazon.com/TEMCo-Hammer-...58001683&sr=8-1&keywords=hammer+crimping+tool

Back several years ago I had it along when I went to visit a buddy and he was having trouble with the battery cables on their big payloaders because he insisted on using those crappy bolt on automotive ends and they would either corrode or burn up all the time.

I had my tool kit with me and my Hammer crimper so I talked him into letting me have a go at fixing his cables. Well first off their cables were rotten form end to end so I told him to get new ones ( buying near 20 feet of 4/0 copper welding cable really made squeal :D) then hammer crimped followed by electronics silver soldering the crimped ends with a glob of silicone smeared over things and to end it put heavy shrink tube over all of that. ;)

Never has had a single problem with that loader and battery cables or batteries since. :cool:

Unfortunately he liked my hammer crimper and how things worked so he went and got one too and had nothing but problems with is cables.

First thing he was doing wrong was not using the propper 2 pound hammer and 3 - 4 good wacks to crimp the new ends on the new cables. He figured that if the 2# hammer was good using their 50 ton hydraulic press would be better. :rolleyes:
Yep he was squeezing them so hard he was extruding the copper cable right out of the connectors. :(

Then to top it off being he didn't have any electronics silver solder he was using acid core plumbing solder that just made everything corrode which between the cable being extruded to near 1/3 its cross section by over crimping and doping it up with high resistance acid core plumbing solder pretty much everyone of his repairs ended in a fiery melt down within a few weeks of month of him doing them thus hiding the incorrectly done crimp and solder job. :oops:
 

tcmtech

Joined Nov 4, 2013
2,867
When I was young (!) almost every installer of audio HI-FI components for cars was soldering after crimping. I don't know if this habit is lost nowdays, but I suspect is not.
That's how I still do it and I have never hand one of my connections made that way fail and a few of them are pushing 20+ years in service in our old farm pickups.
 

AnalogKid

Joined Aug 1, 2013
9,351
When you want to crimp two wires in the same crimp connector then the solder can provide extra-help against pullout forces, since the insulation crimp cannot firmly grab two insulated wires together.
Stated with great confidence, but not correct. Note - I'm talking about a properly crimped ring terminal or Faston, crimped to the manufacturer's specs. The insulation crimp is part of the strain relief for the conductors, but serves no electrical purpose. When crimped correctly, the metal in the strands in the crimp zone flows and reforms This is called coining, and is what happens when coins are stamped. This is better than soldering because a) solder actually is not a very good conductor, and injecting it in between the strands decreases conductivity; and b) there is no wicking, which is the whole point of crimping.
https://en.wikipedia.org/wiki/Coining_(metalworking)

Could be some paranoid fear against breaking the rule #XYZ that would cause braking the rule #ZKY in the manual #WHZ? I mean... I know something about military furnitures and I know the general fear about doing something not stated, validated and signed on some document.
Or it could come from 150 years of experience. In this case, one of the concerns is that the loss of a single connection point might take down multiple circuits. If a ring terminal breaks at its weakest point, the web between the barrel and the tongue, all of the wires in the barrel now are disconnected from whatever the tongue is connected to. Stacking up 4 wires with 4 individual rings means that the web failures are independent of each other. This increases weight (always a thing in aircraft) but increases reliability (always a bigger thing in aircraft) more.

ak
 

Thread Starter

gimpo

Joined Jan 27, 2016
124
Ok, I have to admit... even before posting it I have planned to use silicone to make my crimp-connectors waterproof and protect contacts from oxidation.
I have discovered few months ago a black sealant silicone produced by Loctite (I don't remember the exact product-number) that is damn sticking and high-temperature resistant (can be used for engines too). What a great product!
I plan to inject it in the crimp-connector housing. :D
(I could also cover the connectors crimped zone with it before plugging them into the housing)
 

Marcus2012

Joined Feb 22, 2015
403
Not sure if this has been brought up already but would you consider a junction block instead of crimps? You can get some really nice slim ones with IP66/68 ratings like these older 1750 series from Amphenol. Of course Farnell has to be down for maintenance at the moment so I can't search for them :rolleyes:
 

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Thread Starter

gimpo

Joined Jan 27, 2016
124
Stated with great confidence, but not correct. Note - I'm talking about a properly crimped ring terminal or Faston
This is the magic word "properly". Nobody knows what it means, it changes from manufacturer to manufacturer...

a) solder actually is not a very good conductor
Sure? Check how your semiconductor chips are soldered. Check Bismuto (used by IBM) properties.
A Sn alloy is not a very good conductor? Compared to what? To gold? Yes, you're right in that case.
A solder joint is always the best in terms of contact surface, i.e. conductivity (since it depends on cross-section area measured in square meters).
You can also check thousands of articles stating that "pure" theoretical conductivity of different materials has no significant influence in real applications (the most influencing factor is inductance of wires). Gold is used only for special comm lines operating at Gigahertz frequency for intra and inter-processor data exchange.

Or it could come from 150 years of experience.
Could be. But redundant connectors does not means "better" connectors, they simply means more tolerance against crashes and/or humans errors.
 

Thread Starter

gimpo

Joined Jan 27, 2016
124
Not sure if this has been brought up already but would you consider a junction block instead of crimps? You can get some really nice slim ones with IP66/68 ratings like these older 1750 series from Amphenol. Of course Farnell has to be down for maintenance at the moment so I can't search for them :rolleyes:
Wow this "things" are amazing! :)
Unfortunately I have to "interface" my cables with the pre-existing cables of the motorcycle, I cannot change them, I have to use them.
Also, costs are important. With crimped connector I can arrange a connection, let's say, at 50 cents per couple of pairs. By using that (lovely) parts I think that general costs should be multiplied by 5 or 10... :(

It could be a better world if every vehicle constructor would use connectors like that!
 

Marcus2012

Joined Feb 22, 2015
403
Wow this "things" are amazing! :)
Unfortunately I have to "interface" my cables with the pre-existing cables of the motorcycle, I cannot change them, I have to use them.
Also, costs are important. With crimped connector I can arrange a connection, let's say, at 50 cents per couple of pairs. By using that (lovely) parts I think that general costs should be multiplied by 5 or 10... :(

It could be a better world if every vehicle constructor would use connectors like that!
Yeah they are great I would love it if my car had racks of them in it :D, Amphenol make really good connectors but some are indeed ridiculously priced. Possible I slightly over engineered a solution there :)
 

#12

Joined Nov 30, 2010
18,223
Soldering doesn't make the joint more reliable - in fact, it is just the opposite.
I love the way some people can sum the whole thing up in one sentence. Crimping is more reliable without solder. It has better pull-out strength without solder, resists corrosion creeping in between the strands better without solder, the conductivity of the joint is made worse by adding solder, and adding solder will make the connection fail sooner in the presence of vibration.

Unfortunately, I disagree.:(
 

GopherT

Joined Nov 23, 2012
8,012
Soldering doesn't make the joint more reliable - in fact, it is just the opposite. Crimping is a more reliable joint than soldering.
If a person is a bad crimper and a bad solderer and has no decent crimping tools, I think the crimp plus solder will be the most reliable. On the other hand, a connector designed to solve the problem is likely the best solution. 3M makes all kinds of connectors and room temp curable sealants for splices and butt joints. I'm sure others do as well.
 

Thread Starter

gimpo

Joined Jan 27, 2016
124
Soldering doesn't make the joint more reliable - in fact, it is just the opposite. Crimping is a more reliable joint than soldering.
Hello SLK001, nice to hear you again.
Honestly I like to hear so many people saying that crimp connectors provide reliable connections. I'm forced to use them so your feedback makes me feel more confident about them. Nevertheless there is still a little voice in my mind that is absolutely still not convinced at all.

For example, when you join two wires with solder you get a bullet-proof solid joint. You can try to pull out the wires with all of your strength and... the wire will break but the joint will stay there! The same happens with crimped joints?

Second point is resistance to oxidation: as I know crimped joints needs to be heavily sealed to protect them. The weak point is not the material of the crimp connector itself but the wires made of copper. Air will oxidate them.

Third point is conductivity: a melted joint increases dramatically the area of contact. The cross sectional area rise up as well as conductivity.

To return at my question: would you crimp two (smaller) wires together onto a connector designed just for one (greater) wire? If not, why?
 

Thread Starter

gimpo

Joined Jan 27, 2016
124
how many amps are you looking to split off.
I plan to make around 100 connections over two-poles AMP supersealed connectors as well as another 100 connections over TE-Connectivity connectors of the 070-series:
http://www.te.com/usa-en/product-174463-2.html

AMP connectors are waterproof so no big problems from that front. TE connector have no protection against water or air and I would protect the crimping contact zone as minimum. So I think that I will use the special silicone produced by Loctite.
My idea is to cover the crimped zone with a generous "blob" of silicone and then plug the connector in the housing. It's a bad idea?
 
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