So recently I have decided that I am through with crimp on connectors as a permanent source for splicing wires and attaching fittings. I watched some youtube videos as a tutorial because I don't really have any experience with soldering other than sweating copper pipe and fittings some.

When connecting wires like a butt splice I have seen a few different techniques. The most common is the "X" twist where two ends of the wire are stripped about 3/4", matched about half way together and each side is twisted back onto the other. This allows a flat joint not much bigger than the insulated wire on either side and the heat shrink goes over nicely and looks good when finished.

Also, I have seen a technique where the ends of the wire are tinned before mating them together. Once the ends are covered with solder then they are held side by side and soldered together. I haven't tried this yet and I am not sure what some peoples opinions are about it. I am interested to hear what others think.

One other technique I saw was to fray the ends of the wire, push them together and twist the joint to flatten it out. Then heat and apply solder. I tried this one, but kept having issues with the solder wire sticking to it like when a welding rod gets stuck to the work. I didn't like it so went back to the "X" technique in the first paragraph.

I am interested to hear about what people have done with best results including techniques size of wire and etc.

 

I prefer crimping.
A properly made crimp connection won't come loose, won't corrode and won't degrade the circuit.

Use the right crimper like a ratchet crimper with dies appropriate for the terminal type.
Whenever possible I use uninsulated terminals, both because they allow better sealing from the elements, and because you can see the crimp to make sure it's good before you seal it.
Then apply adhesive lined heat shrink tubing which electrically insulates it and the adhesive seals it from the elements.

 

I would never attempt to tin and hold the wires against each other as that is inviting a "cold" solder joint when you move one wire as the solder cools. And fraying the ends sounds like a mess waiting to happen. So, I go for the X every time.

The way I prepare joints is to play like the solder isn't the electrical connection, just the mechanical one. So, you need to get copper to copper and then put the solder to it. Yes, solder does conduct. And yes, many components like resistors and capacitors are tinned with solder. But getting a good copper/copper joint ensure it will conduct well when you put current to it. That means I want a good amount of overlap and lots of contact.

 

I agree but disagree with Tom for connecting terminals. The only thing I do differently is to put a step between crimping and heat shrinking - I solder the crimped connection. And that is because I disagree about a crimped connection not corroding as they can get moisture in them - even those done on ratcheting crimpers with the right die. If you think about it, twisted wire has all the spaces between strands, and moisture can get in there - and expand from there. So, filling those spaces with solder makes sure that cannot happen.

 

I like soldering myself for a permanent connection. The solder seems to hold up better when the joint is exposed to weather. I am sure a crimp would do just as well if you bought the expensive ones that have the shrink built into them with the glue on the inside, or if you use a regular crimp and slipped a piece of the shrink-wrap on it with the sealing glue inside.

If you do not have the fancier shrink wrap, I think soldering lasts longer. As far as how to join the wires, it depends on the situation. If the wires will have little possibility of mechanical strain on them, pre-tinning both ends and then just melting them together side by side works well for me as is the easiest way to join them. It makes the splice a little bit of a bulge, but not too much. The good thing about this method is it requires less heat to get them joined together.

I have used the method of leaving the wires frayed, jamb them together and then mash the frayed pieces down to make a nice compact joint for when that's needed.

When the priority is a good elec connection AND a good mechanical joint(like a plug-in that sees strain on the wire) I go ahead and form both ends into hooks. I hook them together, and then take pliers and mash the hooks closed. Then apply solder. This gives a good elec joint as well as a very strong mechanical joint.

One problem with soldering on a vehicle; You are usually outside, so if it's cold or the wind is blowing, you can have trouble soldering, especially larger wires. In this case a soldering gun is best, since it gets much hotter than a iron. This is why your solder seemed to stick to your work, you did not have the wire hot enough for the solder to melt and flow.

 

Actually if you use the correct crimper, die and terminals the crimped connection compresses the wires to nearly or completely eliminate the voids. Here's a good link illustrating it: AeroElectric Connection - Crimp Tools Comparison About 2/3's the way down for a cross section.
If you use adhesive lined heat shrink so it seals both ends of the barrel, you won't get any corrosion.
A while back, as a test, I cut open some some crimped connections I'd made, that had been living under the vehicle for 10 years, and they were as bright and shiny as they were when new.
I also cut open one that was done in '85 that experienced New England winters and it was the same.

Really, either one done well will last, and either one done poorly won't last.

If it is any recommendation, Apollo 1 and 13 notwithstanding, NASA uses crimped connections.

 

Tom - I yield to your expertise. BUT, that assumes the Hi-Dollar ratcheting crimper, and while you may have them I really doubt many others do. (I have one but with only the red die.) I don't want them to assume that their El-Cheapo crimper will do the same - as it will not.

 

I like the hook idea Dave. That does sound like a good mechanical connection.

I bought an iron. I think it is a 60 watt iron. I did really look at the gun quite a few times before I got the iron. I usually don't balk at getting a more expensive tool, but both kids are getting their wisdom teeth out and the little woman's college bills are crimping my budget.(pun intended)

 

I'm sure it is a Hi-Dollar ratcheting crimp(er). Not some El-Cheapo? Right?

 

I generally do the frayed-ends-together-then-twist style, I only do the hooks when the wire will be under strain.

I have both a gun and a few irons, the gun is LOTS faster and more satisfying to use.

What is of importance, though, is to have clean wires, no green corrosion or anything. Fine sandpaper can sometimes be used t clean up crappy wires.

 

I usually hook the two wires, then solder together and seal with the self-sealing heat shrink tubing. Never EVER will I use a butt connector! Seen too many failed factory crimp connections. Makes me wonder why they still use them (oh wait...$$$) ~Bill

 

I always use a good FLUX too, even with rosin core, which I believe is supposed to have the flux with it.

 

I am glad this was brought up. Many times when working on a old vehicle, you will find the copper inside the insulation a dull brown color. Even if you have plenty of old wire to work with on the vehicle, and keep cutting and cutting, you may find the copper like this all the way up the wire. Solder will refuse to stick to the copper when it's like this, even with lots of auxiliary flux to clean the wire. I find the only way to get it to begin to stick is strip the wire back, lay the frayed ends down on a wood board something else suitable, and take a knife and scrape the copper so it shines up. Keep turning the wire in different positions to try and clean it up as good as possible. You won't get it absolutely clean, but you will get it clean enough to where the solder will stick in many places on the wire and give you a connection that will work. The sandpaper idea is a good one also.

 

This is the old milspec that I had to learn back in the day, it might help some.

http://www.electromet.com/documents/milstd2000a.pdf

 

I scanned through it Archion. I did see something about "mounting MELF's" in there.

I also was hearing that the pros use real lead based solder still where most of the stuff I saw at RadioShack was lead free.

I think I need to get some smaller diameter wire and that will work better. Seems to take a while to get the stuff to melt.