Splicing Wires

Discussion in 'The Garage' started by trscott, Nov 4, 2007.

  1. Virtual Rider

    Virtual Rider Traveler

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    [​IMG]

    It's basically a ring of solder inside a piece of heavy shrink tube. The colored rings are also heat-activated glue. A heat gun does all the work. If used correctly, renders a water proof seal.

    Before you start the obligatory analyses and critique, they're the ONLY approved splice on many aircraft applications.

    Several companies make them. Here's a link to one:
    http://www.calcentron.com/Pages/fusion_solder_heat_shrink/fusion_solder_heat_shrink.html
    #41
  2. Dolly Sod

    Dolly Sod I want to do right, but not right now

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    I've never had good success with those, but it may be because I'm using a butane torch instead of a heat gun.

    So if they're the only approved method in aircraft applications, what's the approved method for joining the wires before using that thing? Just stick them in over lapping end, or twisting together like Dr. Scott is suggesting in this thread?
    #42
  3. NBeener

    NBeener Long timer

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    Don't remember who makes mine. Grew up in a house where dad had a pair forever, so ... when I started working on auto electrical, I picked up a fairly good pair.

    Once you use a pair (agreed: a decent pair), you'll (cliche here) wonder how you ever lived without them. The only issue is in tight quarters, working with existing wiring. It can be tough to get a bite on the short end of a wire.
    #43
  4. trscott

    trscott Been here awhile

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    Good question...

    I was the guilty party raising some concerns with soldering guns. Interestingly I do own and use a butane soldering iron in special circumstances. One reason that I got one is that I also play arouund with amateur radio, and frequently have occasion to be soldering antenna wires out in the yard, or up a tower where power is a major hassle to provide. They have one advantage over a soldering gun in that you can fire it up and set it down while it heats and then when you pick it up you can expect that it is at full power. Plus, my Weller butane does have a variable heat control so that with a little practice you can figure out what temp setting to use for different applications. Also, like a gas cooking stove, you can adjust the temperature pretty quickly.

    The major problem I have with soldering guns is that you tend to pull the trigger to heat it up just as you want to begin soldering. True they heat up pretty fast, but you really don't have any very good way to know how long it takes and what temperature you're at. My experience is that I've seen an awful lot of bad solder joints done with soldering guns and I think this is why. You start applying heat to the joint before the gun is hot enough, making it take longer to get hot, so the novice starts applying solder to the gun tip instead of to the joint, ending up with a glob of solder melted over the joint instead of having the solder sucked up into the joint. If this were not bad enough, when you hold the trigger long enough, you now have a very hot joint and a rapidly overheating gun. If the reason the solder isn't flowing is because you have too much oxidation someplace, you are now probably making that condition worse.

    That said, it is certainly true that with enough experience you can do a good job soldering with whatever tool you have. With practice I could use a hot pad, a butter knife, and a gas stove, but that wouldn't be my first choice tool for the job.

    The best soldering iron, in my opinion, is a "temperature controlled" iron that has the wattage to maintain the desired temperature before and during the process of applying heat to a solder joint. These come in two basic varieties: one type has special interchangeable magnetic tips for different temperatures, and the other type allows selecting the temperature with a dial, with or without a temperature indicating digital display. The latter are really deluxe and universally used in professional electronics manufacturing today, but can be somewhat expensive.

    One of the simplest temperature controlled irons uses a thermo-magnetic principle to achieve temperature regulation. (Unless I have the principle exactly backwards...) I believe magnets become weaker at higher temperatures. My older wellers have replaceable tips with a number stamped into the base of the tip to indicate the temperature range 600F, 700F, or 800F. These actually have different strengths of magnetic attraction. The iron handle stem where the tips mount has a heated element which either snaps into contact with the tip to heat it, or snaps open to let it cool, in order to regulate the temperature. You can actually hear it snap as it switches. The beauty of this design is that it will idle under no load right at the desired temperature, and then as soon as you begin taking heat out of the tip to heat up a joint, the iron snaps into high power mode and has power to spare to keep the joint right at the desired temperature. Any unregulated iron has a tendency to either be too hot when idling with no load, which leads to excessive oxidation of the tip, or too cold when trying to heat up a joint.

    With a little practice on a variable temp butane soldering iron, you can simulate the effect of a temperature controlled iron by dialing the power down a bit while it is idling in its stand, and then dial it up to the desired power setting just before you begin soldering.

    Soldering iron tip maintenance is also important to easy soldering. The tip should be clean and bright. You can get this by cleaning it against a damp sponge often, and re-applying a small amount of solder to the tip periodically. A quick wipe on a damp sponge doesn't really cool the tip very much, but actually steam-cleans the tip as the water instantly vaporizes on contact with the iron and boils off most of the corrosion and slag. There are also very helpful tip re-conditioning pots which have a mixture of flux and solder. These come in a little tin about 1" diameter and 3/8" thick with double sticky foam tape on the bottom so you can stick it to your soldering iron stand. You just stab the tip into the pot, let it melt the solder and flux for a few seconds, and then wipe off the excess on a sponge. If your tip is heavily oxidized and does not look clean and bright after this treatment, you may have no choice but to file or sand the surface down to clean bright metal again. But don't resort to this unless you have to. Good soldering iron tips will have something like iron plating which you will lose when you file it down. If you do file it down to clean metal, immediately re-tin the entire bare surface of the tip with solder to minimize the oxidation process. Controlled temperature soldering irons are far easier to maintain a good bright tip, because they do not tend to overheat the tip while idling.

    Again, all of these tools can do fine work in the hands of an experienced user. The key to good soldering is to understand heat transfer principles; heat the joint very quickly, and apply the solder to the opposite side of the joint from where you are applying heat with the iron. A wire splice solder joint should only take a couple of seconds. If the first application does not result in a completely satisfactory solder joint, you are usually better off to let it cool down completely before trying again. If you are having trouble getting the solder to melt with this technique, you almost certainly need a hotter (or higher wattage) iron.

    One final comment about butane. I briefly toyed with the idea of adding it to my travel tool kit, but decided that for a field repair, I was completely happy with an electrical first aid kit that consists of: a length of several feet of 16 or 18 gauge wire, a handful of butt splice crimp connectors, some vinyl electrical tape, and the leatherman tool that I always carry. These supplies take almost no space, and can take care of any field repair that I am likely to want to take on in the field, well enough to get me back to a workshop. Even a hidden failed ground connection point could theoretically be troubleshot and fixed temporarily with this. A 12V LED with some short wires attached would also be insignificantly small and could prove pretty useful.
    #44
  5. trscott

    trscott Been here awhile

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    I am sure these can work fine, but before you put too much stock in what some agency will "approve" remember that their criteria for an acceptable method may be different than ours. They tend to prefer solutions that will be acceptable when applied by any fool (aka, the origin of the term "foolproof"). That may be not be the best method, given some practiced skill and training. Knowing that not all have access to this training, I have tried to offer some assistance in that regard here.

    Still, I will not argue that these splices you've proposed, and a whole host of other things like Scotch locks, crimp-ons, and so on may not result in perfectly acceptable connections, but I will stand by the technique I've suggested as my preference for permanent and absolutely reliable connections. In my opinion, the splice I've shown is the best method given a certain level of manual dexterity and practice.
    #45
  6. trscott

    trscott Been here awhile

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    This is certainly another area that is prone to debate. I used to prefer something like you suggest (without the liquid tape, more about that shortly), on the basis that I didn't want to cut the original wire if I didn't have to, but have evolved to preferring to cut the wire and then use the splice I've detailed above with the third wire just twisted together with one of the other two. This allows a couple things: First you can get heat shrink onto the joint and I really like heat shrink. Second, if you need to lengthen the wire as you tee into it, you can easily do so.

    The trouble with the liquid tape is that it is difficult to insure a uniform or minimum thickness everywhere. Liquids tend to flow so they are deeper in the valleys and thinner on the peaks. This is exactly contrary to what is needed. Tape materials tend to insure a minimum thickness and heat shrink actually thickens as it shrinks. The dielectric (insulative) capability of a material is a direct combination of the characteristics of the material (electron mobility) and its thickness.

    If you really want to solder a Tee splice without cutting the original wire, here are two methods I have used:
    1) If the original wire is longer than needed and has some slack to it, you could remove a double length section of insulation and double it over, then treat that as one wire, and splice it to your Tee wire using the method that began this thread, and heat shrink as usual.
    2) If you don't have any slack, you could do as you suggested, but instead of liquid tape, I would wrap with approved electrical tape and then maybe add a wire tie to keep the tape from unraveling. The vulcanizing tape may be another good solution, but I can't say I've used it enough to know how it would hold up over the long term.
    #46
  7. NBeener

    NBeener Long timer

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    So ... what about friction tape??

    Is this a dinosaur? I always seem to have a roll or two laying around, but ... damned if I ever use it.

    Is it a good thing to throw on after you've soldered, shrink-wrapped, and (possibly) electrical taped??
    #47
  8. trscott

    trscott Been here awhile

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    Well, how shall I say this...?

    Take a clue from how often you use it...?

    I like heat shrink. Maybe the best invention to come to electronics since the transistor. It won't unravel, it doesn't get sticky and gooey when it gets old, it can shrink down to an air-tight seal. It comes in many colors so you can color code things, and it comes in many sizes. You can get varieties that will shrink 3 to 1 or more. You can even get a marine grade that is lined with a heat glue to help make a water tight seal around irregular shapes.

    As for the friction tape, I don't know, put it someplace you need friction? If you want to keep errant electrons in line, there are better products for the purpose today. Hey, I like old cars and swing music from the fifties; I can remember when we used cotton to insulate wire, and I've seen houses plumbed for gas lamps in the hallways and bedrooms, but not everything old is a real good idea today.
    #48
  9. Scrubs

    Scrubs erm

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    #49
  10. Virtual Rider

    Virtual Rider Traveler

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    I had no intention of arguing against the technique you show here. I've used it or VERY similar and know for a fact that it's good. Sorry if I gave that impression. I was just throwing out another option.
    #50
  11. Virtual Rider

    Virtual Rider Traveler

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    These do almost demand a heat gun with a round diflector. You also must heat them somewhat slowly (very very hard with a torch) so the solder inside can rise to the correct temp without burning the insulation (shrink).

    If I understand your question correctly, you overlap the ends without twisting them.
    #51
  12. trscott

    trscott Been here awhile

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    No offense taken, nor intended. Just saying that "agency approval" doesn't necessarily mean very much. I have seen lots of cases where someone like the UL or the FAA or the FCC will "approve" something for reasons that seem good to them, but verge on the lunatic from another point of view. Very often, as I tried to say, I believe this is the result of trying to come up with a "foolproof" method. If you have to restrict yourself to things that a "fool" can't screw up, you often throw out the "best" method which might require a bit more skill. :deal

    Cheers!
    #52
  13. JimVonBaden

    JimVonBaden "Cool" Aid! Supporter

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    Excellent tutorial!

    I learned to solder 20 years ago in the Air Force, and have used it successfully for years. I still prefer it in most applications.

    Jim :brow
    #53
  14. DaveF-

    DaveF- Adventurer

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    Years ago I picked up a tip from a Motorola technician on prolonging the life of soldering station tips. I had been having trouble with them becoming oxidized and pitted after several weeks of continuous use, and then needing replacement.

    Simply tin the tip so it's thoroughly coated with solder prior to switching the soldering station off. Also, if it's going to be idling for an extended period, tin the tip prior to setting the handle down.

    He was right. Tips used to last a few weeks for me; the time jumped to a few years.
    #54
  15. Scrubs

    Scrubs erm

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    Why is it that the solder wont stick to the tip sometimes when
    I am trying to coat/tin it. Is the iron too hot or something?
    #55
  16. FrisbeeR1200GS

    FrisbeeR1200GS Been here awhile

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    Studied the pictures, read the words, sent the info to three guys on my "A" list....those on my "B" list are not yet worthy! :lol3
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  17. johnjen

    johnjen Now, even more NOW!…

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    The tip must be 'clean' which is why a wet sponge is used to wipe the tip before solder is melted on it. You could also use a jar of flux paste but a wet sponge is quicker.

    JJ
    #57
  18. trscott

    trscott Been here awhile

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    Usually a failure to accept solder is a function of oxidation. If it isn't too bad, you should be able to boil it off with a wet sponge, if it is worse than that, a good flux pot can do wonders, but if it is real bad, you can be stuck with filing it off to bare metal. The real key is to keep it tinned. Every time I solder a joint, I wipe the tip off on a damp sponge before putting it back in the stand, and I frequently re-tin it in a flux and tin pot mounted to the iron stand.

    The cause of excessive oxidation may well be an iron that is idling too hot for too long, so the heat can be a factor, but not directly the cause.
    #58
  19. the kaz

    the kaz has become "FERAL"

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    TRSCOTT great thread :D
    When there is time that is the way to go :D
    In the field I do use crimps with heat shrink on them though :(:

    I have a question though ? Why use two pieces of heat shrink ? And looks like your useing single wall ?

    Here at work everything gets just one layer of double wall and we haven't had any issues. And I really don't want to talk about some of the lengths we go through to make an add on splice without cutting the orginal wire and still useing heat shrink :eek1
    #59
  20. trscott

    trscott Been here awhile

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    Thanks!

    I agree, crimps are a great field expedient.

    I have actually never used the double wall, although I am sure it would provide the necessary dielectric thickness. The one advantage of using two layers of single wall, as I pointed out in the tutorial, is that by making them different lengths, you can get a bit better strain relief to protect the wire against breakage if it has to endure flexing. If it won't get flexed, I don't suppose there is any difference using the double wall.

    In an industrial environment the criteria for selecting a solution isn't always relevant to our needs. Anything that saves labor is attractive when labor costs what it does today. But if I am doing my own work, I have the luxury of not worrying about the time it takes.

    Cheers!
    #60