Soldering vs Crimping

[jmnjrpa]

Steve,I see where your'e coming from

but, I will continue to soldier my connections simply because they give me less problems that way. BTW - when you reach the heat it takes to melt soldier you are aready on your way to a good fire with most insulations.

[DeanR]

Soldering vs Crimping

Neither one for lots of stuff...Posi-Lock connectors

[clcorbin]

Ok, I'll take these in order...

Tod: No, you still are confusing electronics and electrical. Yes, solder is commonly used in the electronics industy, and on more than just circuit boards. And they don't refer to 'Aircraft Electrical', but call it 'Aircraft Electronics'. But in the electrical field, solder connections are illegal 'unless part of an approved assembly', i.e. is a factory assembled item and has a testing lab approval such as UL. If I had a current copy of the NEC, I could quote the pertinent section but what it says is ALL field connections 'shall be made by mechanical means', no exceptions.

Steve,

I hate to tell you this, but the NEC has absolutely NOTHING to say about the wiring on plains, trains and automobiles (or boats...). NOTHING. Neither does the Underwriters Laboratory.

There are two huge issues with any electrical connection on an automobile: corrosion and mechanical stress caused by vibration (your house just doesn't sit there and buzz for hours on end. At least, I hope it doesn't!).

Corrosion is fairly simple to address. You have to make sure no air or moisture (or other crap) can get to the joint in question. Good connectors do this with proper seals and sealing gel. The other stand by is adhesive lined heat shrink tubing over a splice or connector (if possible).

Vibration is another ball game all together. Let's look at an inline splice (aka: hacking the wiring harness!) first. In an uncut strand of wire, the forces are passing through all the strands of the wire (Notice that you will NOT find solid strand wire on things that move. Vibration is why.) Because each strand is very small, the actual bending on each section of wire is very small. The more flexible the joint has to be, the small each strand is and the greater the number of strands to get the current carrying capacity needed. Also, the continuous insulation over the wire helps to carry the mechanical loads (bending and other) while at the same time provides damping to the vibrations to keep the amplitude down.

What happens when we put a solder crimp in there with maybe a single wrap of electrical tap to insulate it? Well, in the zone where the wires are physically soldered, that wire is now acting like a single, large diameter wire. Plus, there is no continuous layer of insulation over the joint, so there is no mechanical support nor any damping. Over time, the vibration will fatigue and eventually break the wire very close to the splice. The amplitude of the vibration will determine how long this will take.

If we place a layer (or two) of our good, adhesive heat shrink tubing over the splice we do two things to improve it: Moisture and air can no longer get to the soldered joint (and even exposed copper wire) to support corrosion, and we have mechanically supported our splice as well as dampened down the vibration at the splice. All good things. But the soldered splice is STILL acting like a single large wire and it WILL fatigue and fail before the multistrand wire around it would.

When we upgrade this soldered splice to a crimped splice, we take that "single large wire" problem out of the picture. That DOES improve the splices ability to withstand vibration and it DOES increase the life of the joint.

Now Tod was talking about something ALL TOGETHER DIFFERENT than this type of splice. He was talking about a solder cup Cannon plug ASSEMBLY. This plug uses pins with a small "cup" on the end of each pin that the wire is inserted into and then soldered in place. By itself, this connection would have the exact same problems as our soldered splice example.

But the plug is an assembly. It has additional components that restrain and dampen the wires movement inside the plug assembly. When it is put together properly, there is almost no vibration relative to the wire and the pin, therefore there is almost no fatigue at that joint.

These things are fantastic, but they cost an arm and a couple of legs EACH. The huge advantage of them is you can replace a damaged pin without having to cut the wire back. Field repairs can be done without coming up with some "slack" in the cable assembly (which you won't find on most aircraft wiring harnesses anyway) by unsoldering the damaged pin, cleaning the wire and soldering it to a new pin before reassembling the Cannon plug.

As for crimping damaging the wires, well, yes and no. A properly made crimp with the correct terminal for the wire using the CORRECT crimping pliers and CORRECT procedure will not damage the wire. It WILL deform each strand slightly as the group of strands are tightly compressed together inside the connector. But they won't be nicked, stretched or damaged in any way.

The real trick here is using the correct tools. Those $30 parts store crimpers are not the correct tools. Depending on the connector you are crimping, it could very easily require specialized crimping pliers that cost several hundred dollars a pair. The vast majority of backyard mechanics (and WAY too many professional auto mechanics!) do NOT have the correct pliers and they WILL produce a marginal crimp with the pliers they do have (to tight, to loose, wrong shape, etc) almost every single time. If the crimp lasts longer than they own the vehicle, I guess it was "good enough". That would NEVER work on a critical system (or even non critical) on an aircraft.

For my vehicles, I'll take a properly done crimp connection (with adhesive heat shrink) any time. But if someone else wants to pay for the Cannon plugs, they are definitely top class!

[crazy steve]

Clint:

Uh, isn't that what I said?

I know the NEC has nothing to do cars, planes, etc. I merely brought this up to show that people smarter than me say it's a bad thing used in the wrong place.

There are some very cool vehicle wiring connector methods out there, but they're not particularly cheap. Tyco and Deutsch are two types I've used personally. The Deutsch is my fav when I can afford it, with crimp-on pins/plugs, and cool little silicon seals for everything. But at about $5 for just a two-wire plug, and over $20 for a eight-wire, you can have a lot of money in a harness real fast...

'78E original owner

[Larrym]

Two Ends Make Up the Middle???

crazy steve,

Ok....Ya got me with you on the "solderless" end-connector. (Though every time I crimp I'll also cringe cause I do so love to get out my soldering station..) That's cause I really do use the ABYC standards on my boat and it's so hard to switch behavioral gears when I work on anything else.

The ABYC standards prohibit soldering as the sole means of making a connection so I tend to follow up with flowing on some solder after making a good mechanical connection. (Not as in "the bigger the blob-the better the job.") I'll try to resist the compulsion for every little bullet and spade connection I see from now on.

After the barrage of arrows coming at you slow down maybe we can find out what you do for splices??

Am I the only one who does this:



The oldest telegraph splice - the original mainstay of telegraph wire connections is known, appropriately enough, as the Western Union joint. 'Cold' (that is; not soldered - just twisted together), it is about 65 percent efficient and retains about 55 percent of the strength of the wire. Soldered, it becomes over 95 percent efficient.

or this:



Just twist two wires together - - - You probably have been making McIntire joints for years and didn't know there was a name for them. The McIntire joint is made by grasping two opposing wires at a midpoint about two inches from the ends and wrapping each end around the wire at least four revolutions. Cold, the McIntire joint ranks as about 70 percent efficient and retains about 75 percent of the strength of the wire. Soldered, it also becomes over 95 percent efficient.

or sometimes this:




Though not really the standards most PO's live up to, I'm used to following rules similar to:

THIS.

It comes from working on robots/machinery that did move and vibrate. The western union splice was approved at least in that environment.

So, if you survive the onslaught of "holy water" splashed on you, somewhere near the end of this thread I'd like to hear your views about splices??

If you don't survive...well, I'll be the guy in the back of the angry mob as you're carried off to the already growing burn-pile. Nothing personal. I just like waving a pitch-fork or carrying a torch as much as the next guy.

[crazy steve]

...ABYC standards prohibit soldering as the sole means of making a connection so I tend to follow up with flowing on some solder after making a good mechanical connection...

So, if you survive the onslaught of "holy water" splashed on you, somewhere near the end of this thread I'd like to hear your views about splices??

I'm not worried; after their solder joints fail, they'll be too tired to do anything after pushing a 600 lb motorcycle to my house!

You bring up one other thing with the ABYC standards; the importance of crimping first. Crimp connectors work poorly on single-strand wire (and if you've soldered first, that's what you have) and even if you do more soldering after crimping, you still probably have a solder-only joint. But solder after is no better, as now you have more mass to get hot and the chances of wire damage go up.

I know about the 'western union'; there's also the rat-tail, end fixture, back turn, britannia, and scarf types to name a few more. Virtually none of them are used any longer in the electrical industry; they all went out with solder. The last users of soldered joints were the utility companies for high voltage splices (who don't fall under the NEC by the way) and they ditched it as soon as the HV 'kits' came out. Some of this is maybe still used in the telephone industry though, but I doubt it. The few times I used any of these, it was used to either add a wire to a conduit run or replace a damaged or too-short wire; the splice was pulled through and out. Splicing of any wire, while allowed under certain conditions, is frowned on.

How do I splice on bikes/cars? Two ends, I use a butt splice. Three to four wires (one and two, or two each end), I'll calculate wire area and use the appropiate size (example: two #14 are roughly equal to a #12 in area). If need be, I'll 'fill' one end by doubling the wire. Any more than that, I'll stagger the splices or take them to a terminal, but I try very hard to avoid 'extra' splices; every joint is a potential trouble spot. The interesting part about your NASA specs is they specifically tell you not to locate any joint where there may be flex and stress proper support. And all of these look to be 'electronic' type splices, not 'power'. I'm somewhat surprised they even allow splicing on spacecraft, I wouldn't like it.

On an unrelated side note, one thing I did when I built the harness for my chopper (starting with several 'partial' harnesses) was to have only two grounding points. I put a 'main' grounding terminal under the seat (tied with #12 directly to the engine case along with the battery cable) and ran a #12 from it to the headlight bucket. Here, I put in a 'ground buss' (just a piece of 3/16" aluminum with a bunch of tapped holes). Everything behind the motor went to the 'main', all the rest went the front 'ground'. Any ground issues, I only have two places to look, and no worries about exposed/rusty connections. It took very little extra wire to do this.

'78E original owner

[GARTHXS]

this is getting good

almost as good as your harley thread Steve, very interesting and more than I ever really wanted to Know about connections, but seriously how do you keep the smoke from coming out of the wires

[81xsproject]

Wow. Serious controversy and heated debate in a electrical connector thread; I never would have pegged this one for a Hot Topic

[psycoreefer]

I always just twist the two wires together and then put some tape over them....

I know a guy who uses wire nuts for everything...so where to wire nuts fall, between solder and proper crimps?

[Ivan]

Interesting about that Western Union and such joints. When I do solder, usually because I have run out of weather proof crimps and the parts store is an inconvienient 30 minutes away, I use the Macintire type joint and then flowe the solder into it with plenty of flux. Done right, the joint will not be any larger than the insulation on the oiriginal wiring. Good quality weatherproof heat shrink will make a durable long lasting splice.

Still, in all reality, vibration and corrosion are the enemies of electrical connections. On my machines (Model helis, cars, motorcycles, and what not) I spend a lot of time making sure the wiring is routed well and is secured and as neat as possible. I think this is the most critical step in any wiring repair, because any crimp, solder joint or even (God have mercy on the blasphemous and evil) twist and tape will not fail as quickly with a stable wiring harness. Indeed, I go through zip ties and wire loom at an alarming rate. But, I know I never have to worry about electrical joints failing because they break at the splice.

Psycoreffer, I hope your twist and tape comment was in jest, because I got a few select words for you if not.

[psycoreefer]

Psycoreffer, I hope your twist and tape comment was in jest, because I got a few select words for you if not.

It was, just adding fuel to the fire! I usually try to find "factory" style plugs when ever possible so I don't have to cut and splice. I figure the more I can leave the factory part of the harness alone the better off I am.

[DenyP]

Most of the problem folks run into when soldering old wiring can be assigned to

1, Incorrect prep of the wire joint.
2, Wrong solder
3, incorrect heat

Over time oxidation will creep up the wire under the insulation. You have to cut the wire back a bit to get clean metal. This makes using a soldered connection as a repair difficult in the field. But if one takes their time, uses the proper materials and a regulated soldering iron / station it can not be beat for connection integrity, low resistance and life expectancy.

Industrial quality crimping tools have a die or die area that is matched to the terminal to be installed and the wire and insulation size being used. It is rare to find a universal crimping tool that does a good job.

Production harness manufacture is ALL about making a good crimp in the shortest possible time. The use of crimped connectors is not chosen because it is the best electrically but because it is much cheaper.

I don't say any of this due to opinion. I worked in the electronics industry over 20 years and manufacturing over 30.

Deny

[Ivan]

Psyco stirring the pot on purpose? Could it be I have a new protoge?

[crazy steve]

...Still, in all reality, vibration and corrosion are the enemies of electrical connections. On my machines (Model helis, cars, motorcycles, and what not) I spend a lot of time making sure the wiring is routed well and is secured and as neat as possible. I think this is the most critical step in any wiring repair, because any crimp, solder joint or even (God have mercy on the blasphemous and evil) twist and tape will not fail as quickly with a stable wiring harness. Indeed, I go through zip ties and wire loom at an alarming rate. But, I know I never have to worry about electrical joints failing because they break at the splice.

Ivan's put his finger on one the main issues; not having this stuff moving around. Will every solder joint fail? Of course not. All I was trying to point out was that while a solder joint may be slightly better in terms of electrical properties, it is inferior in terms of mechanical stength and durability when compared to a properly done mechanical crimp, particularly if vibration or movement is present. And like Ivan, I'll tiewrap a harness down everywhere I can. One thing I do differently is I don't like 'loom' coverings, preferring to tape-wrap mine; and not with the cheap parts house tape either. I'll use the good stuff like Scotch 33 or Plymouth brand tape. There's a huge difference in tape quality, as these will stay wrapped while the cheap crap will dry out and unravel.

To me it's a no-brainer. Invest $25 or so in a crimp tool, take a bit of care with the crimp and put a shrink over it (which you should be doing no matter what method you use) and you have a good connection. For those who are using just solder or soldered crimps, it's less complicated. What's not to like?

'78E original owner

[Ivan]

On automotive I ALWAYS wrap with tape and then loom for abrasion resistance. the tape keeps the harness clean and dry if done right. The loom keeps it from rubbing holes in it.

To be honest though, I just went with tape around the harness on the scoot. It is held in place at enough points I don't think the loom is necessary. I will probably eat my words though.