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Old 02-05-2013, 09:25   #106
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Re: How do you Crimp #8 AWG Terminals?

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Originally Posted by Reefmagnet View Post
I also have doubts a high resistance solder connection alone would get anywhere near hot enough to melt the solder.
12v systems have fairly high currents running in power circuits (hence the heavy gauge wire we see). It's entirely possible for the energy dissipated in a failing connection to melt solder. The failure could be from the bolt securing the soldered lug coming loose, for example.

Heck, some failures will melt copper, which has a much higher melting point.
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Old 02-05-2013, 09:32   #107
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Old 02-05-2013, 09:55   #108
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Re: How do you Crimp #8 AWG Terminals?

I was trained as an aircraft electrican. You just don't solder terminals unless you have no choice. Pins in plugs, inside devices etc. is where you use solder. Sometimes you just can't crimp a connection so maybe then use solder.
A good rule of thumb is, if you can pull the the terminal off you loose. I always test every crimp and every once and a while you get the sick feeling as one does come off. The crimped connection is supposed to be as strong as the wire itself. Pretty hard to test but if you give it an honest pull it will not come off. I have seen wrecked aircraft with the engines held on by starter/generator cables only.
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Old 02-05-2013, 12:58   #109
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Re: How do you Crimp #8 AWG Terminals?

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They are selling a product. Of course they will say it's better. It is not.

To start with, what dummy would put the lug in a metal vise (AKA heat sink) to solder it?

Second. there's no way to hold the connection steady until the solder solidifies. Let it move just a bit and you have a perfect "cold solder joint" (look it up).

They haven't done anything that you couldn't do at less cost with rosin core electrical grade wire solder and a piece of heat shrink tubing.
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Old 02-05-2013, 14:55   #110
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Re: How do you Crimp #8 AWG Terminals?

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I've done a number of things in my life. My summer job in High School was building Mil Spec versions of Tektronix oscilloscopes and other test gear. I've factually made millions of solder joints. I'm out of practice now but have skill.

To do a good job on a #8 wire would take a hefty iron - you need to heat the wire and lug quickly so as to reach the melting temp long before the flux burns off. And to prevent the heat from heading up the wire which will promote wicking and melt the insulation. You need to hold the wire and lug rigid till the solder solidifies. And then you need to clean the flux off.

All this takes time and skill. Then add in the supports to keep vibration from causing fractures.

I'm not saying that it cannot be done - Far from that. It just makes me wonder why a person would spend a minute or few soldering when a nice crimp tool does a good job time and time again in just a few seconds. To each their own I suppose.

Oh and by the way. I still do a lot of soldering. I build mic preamps and discrete op amps (Jensen 990s) and I use 2% silver solder which has a greater conductivity than plain lead/tin solder.

Regards
And I've previously worked in the arc welding and industrial automation field as an electrical engineer for more years then I cared to remember and have crimped and soldered more than my fair share of connections. Soldering is a skill, but an easy to learn one. Crimpers aren't always at hand. Field repairs often involve improvision and more than once a repair has been done by hammering down a lug and then slapping solder in the joint. And the cables I'm talking about cannot be soldered with any soldering iron - they require a gas torch.

If you refer to my first post re solder I specifically mentioned using an appropriate gas torch for heavy gauge cable.

And... I have never seen a fatigue related failure of a heavy gauge correctly soldered connection. Signal wires and cold joints yes, but otherwise no.
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Old 02-05-2013, 15:08   #111
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Re: How do you Crimp #8 AWG Terminals?

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Originally Posted by Lake-Effect View Post
12v systems have fairly high currents running in power circuits (hence the heavy gauge wire we see). It's entirely possible for the energy dissipated in a failing connection to melt solder. The failure could be from the bolt securing the soldered lug coming loose, for example.

Heck, some failures will melt copper, which has a much higher melting point.
Arc welding systems have even higher currents and bad connections can get hot enough to cause serious burns if you are unfortunate to touch them. I've still never seen solder melt out of these connections. Catastrophic failures on the other hand can melt copper, aluminium and even steel so solder melting would be the least of your problems.

Someone mentioned previously that it might be a good idea if the cables dropped away during catastrophic failure due to melting solder. Just last night a boat caught fire at the Coffs Harbour Marina NSW and while the fire fighters were trying to extinguish it, the motor started which caused the boat to start plowing through other vessels in the marina whilst fully ablaze. Perhaps if the a soldered joint had given up that wouldn't have occurred?
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Old 02-05-2013, 15:16   #112
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Re: How do you Crimp #8 AWG Terminals?

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Originally Posted by rwidman View Post
They are selling a product. Of course they will say it's better. It is not.

To start with, what dummy would put the lug in a metal vise (AKA heat sink) to solder it?

Second. there's no way to hold the connection steady until the solder solidifies. Let it move just a bit and you have a perfect "cold solder joint" (look it up).

They haven't done anything that you couldn't do at less cost with rosin core electrical grade wire solder and a piece of heat shrink tubing.
Re the vice: That's basically how we soldered lugs in the field and sometimes the factory as well. Lug in the vice, hold the cable and go for it with solder and gas torch. With practice you don't end up with cold joints. At the place I worked, production soldered lugs were made by crimping the lug with a press and then dipping the the end of the cable and lug in a pot of molten solder for an amount of time. These were industrial welding cables and crimped lugs without soldering would not hold up in service.
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Old 02-05-2013, 15:49   #113
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Re: How do you Crimp #8 AWG Terminals?

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Originally Posted by Reefmagnet View Post
... At the place I worked, production soldered lugs were made by crimping the lug with a press and then dipping the the end of the cable and lug in a pot of molten solder for an amount of time. These were industrial welding cables and crimped lugs without soldering would not hold up in service.
Why would anyone want to solder, an already gas tight (& cold welded) crimp connection?

Where would the solder go; and what advantage would it provide?

On the other hand, soldering a crimped connection might:
- render an unintended & unsupported “hard spot” on the conductor
- anneal the connector, softening it and “relaxing” the fitting barrel (loosening the crimp)
- add another dissimilar metal into the connection mix
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Old 02-05-2013, 16:54   #114
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Re: How do you Crimp #8 AWG Terminals?

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Originally Posted by GordMay View Post
Why would anyone want to solder, an already gas tight (& cold welded) crimp connection?

Where would the solder go; and what advantage would it provide?

On the other hand, soldering a crimped connection might:
- render an unintended & unsupported “hard spot” on the conductor
- anneal the connector, softening it and “relaxing” the fitting barrel (loosening the crimp)
- add another dissimilar metal into the connection mix
This argument is getting lost in generalities. I'm not personally claiming that soldering is better than crimping, I'm simply putting forward the argument that soldering of #8 gauge cable and above is not the precursor to failure that many on here are implying.

Now to respond to your questions Gord:

I've seen crimped + crimped & soldered power cables after extended use in the field and the soldered cables survive much better. The company I referred to earlier is a Multinational US company that is a major participant in the welding industry and that was standard practice for industrial welding cable manufacture. The solder may not penetrate into all areas of the crimp, but capillary attraction draws it into amazingly small spaces and seals the crimp. Many large lugs aren't really gas tight. If you look at the rear, they can have a seam and some even have an opening.

I'm not sold on this concept of "cold welding". I don't doubt its possible, but I can't say I've ever seen it occur in fine strand flexible cable and I find it hard to believe that a copper oxygen alloy, with it's protective oxide layer, can be fused together cold at normal crimping pressures.

I'd expect a "hard spot" on a connector that was "cold welded" anyway. A non flexible to flexible interface is just that whether it's cold welded or soldered.

Copper work hardens and requires around 750 deg C to anneal. The normal approach in annealing copper is to heat to a dull red colour. Solder melts at around the mid 200 deg C mark so done properly there is no issue of annealing the copper lug.

50/50 Lead and tin solder sits adjacent to copper on the galvanic table.

I have to say that the only evidence against soldered connections produced in this thread has been some pictures of dodgy or overheated crimp connections. To me thats like debating Chryslers are more reliable than Fords by showing pictures of broken down Chryslers.
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Old 02-05-2013, 17:33   #115
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Re: How do you Crimp #8 AWG Terminals?

I don't know what else to say here. There are several posters who understand why properly made crimps are the best method of connecting terminals to wire or cable and they understand that attempting to solder after crimping adds nothing and can even detract from the connection.

But, there are also several posters willing to go to great lengths to defend poor practices. It's almost as if they feel that if they can convince enough people, their method will be accepted as the best.

If anyone is going to learn anything constructive from this thread, they have already learned it. The rest will go to their graves believing what they believe without considering that it might not be the best way.

So - I'm done. It doesn't matter what anyone else thinks.
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Old 02-05-2013, 17:46   #116
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Re: How do you Crimp #8 AWG Terminals?

Amen

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Old 03-05-2013, 02:21   #117
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Re: How do you Crimp #8 AWG Terminals?

Quote:
Originally Posted by GordMay View Post
Why would anyone want to solder, an already gas tight (& cold welded) crimp connection?

Where would the solder go; and what advantage would it provide?

On the other hand, soldering a crimped connection might:
- render an unintended & unsupported “hard spot” on the conductor
- anneal the connector, softening it and “relaxing” the fitting barrel (loosening the crimp)
- add another dissimilar metal into the connection mix
You know I have only seen one large crimp connector that was probably gas-tight and that was decades ago. I don't recall the details but the cable was about 1.25 inches in diameter with about 400 strands of copper. It was crimped using a large floor mounted hydraulic crimper and we cut one of the crimped lugs in half. It was smoothed off and then highly polished. Using a x200 instrument microscope, each strand was clearly seen to hexagonal and with no air gaps between the strands. I truly believe it would have qualified as gas-tight.

However since then, we have occasionally (very occasionally ) repeated the experiment using smaller cables (4 & 8 AWG) crimped with normal but good quality crimpers. We have always found very small voids (air gaps) among the strands and the proof of these was to solder some of the crimp connections. You could then see small veins of solder where it had run into these air gaps.

The long and short of these observations is that while the principle of a gas tight crimp connection is sound, the reality falls far short of the principle in most cases. I would go so far to say that almost all good workman like crimp connections using calibrated hand crimpers will still have air gaps (voids) between some of the strands.

Does this matter, well probably not; but don't believe the rhetoric that crimp connections are gas tight unless they were carried out in a very controlled manner using exotic high end equipment.

Guys, as others have said, believe what you want from whatever sources you want but if you want to know the facts, do your own analysis. You might be surprised by what you find and it just be different than what you have been told.


By the way I am not advocating that either method is superior, rather that the foundation principles of crimping is rarely achieved in practice.
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Old 03-05-2013, 07:26   #118
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Re: How do you Crimp #8 AWG Terminals?

Chrysler products are better than Ford. But Fords are pretty.
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Old 03-05-2013, 08:03   #119
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Re: How do you Crimp #8 AWG Terminals?

After 118 replies, this thread is approaching the logic observed in the following "threads":
> "Which anchor is best?"
> "Should I carry guns aboard?"
> "Catamarans are better/safer/faster than mono-hulls!"
> "Mono-hulls are better/safer/faster than catamarans!"
> "LFPs are superior to LA!"
> "LA are superior to LFPs!"

We are now arguing about how many angels can dance on the head of a pin! ;-)
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Old 03-05-2013, 08:10   #120
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Re: How do you Crimp #8 AWG Terminals?

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We are now arguing about how many angels can dance on the head of a pin! ;-)
three, two are crimped and one is soldered on.
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