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Thread: Soldering weeny things...?

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  1. #1
    Join Date
    Jul 2014
    Posts
    383

    Default Soldering weeny things...?

    Hello

    So last night something odd happened. I was trying to solder a little piece of sterling tube (2.5 x 3.5mm) to a little piece of sheet (maybe a quarter inch square and 0.5mm thick). And the solder wouldn't flow. Now normally I'm fine soldering a bezel to a base plate, but normally, I'd be using medium solder and it'd be bigger. For this one I was using hard solder (why not it was the first join), and it was a smaller piece of sheet than I'd ever used before. First time round I probably didn't use enough flux, but I pickled cleaned and tried again and still no. It got to glowy melty hot both times, but the solder sat there in a stubborn lump. On the third attempt it got so hot it pitted - so i'll be starting again.

    All I can think is maybe I heated it too fast? the little pieces seemed to get hot very quickly and I guess had a small surface area to cool down. Is it possible to heat something so fast it 'misses' solder flowing temp?

    Either that or its some weirdery about using tube?

    I'd be greatful for any ideas

    Thanks,

    Faith

  2. #2
    Join Date
    Jan 2014
    Location
    Brisbane, Australia
    Posts
    67

    Default

    Perhaps your hard solder is oxidised, as you say you dont use it often. Try sanding or pickling the solder to clean it up.

  3. #3
    Join Date
    Aug 2010
    Location
    England
    Posts
    1,902

    Default

    Faith. if you are using strip hard solder it is usually quite a wide strip, I usually pierce down the centre of the strip to give me small pieces of solder, after piercing I file or scrape both sides of the solder strip before cutting off my solder pieces.
    after cleaning the solder surfaces, I flux them with borax, gently heat the item then using tweezers I dip the solder pieces in some flux before attaching the solder piece to the hot solder join, as the piece is still warm the solder will stick to the solder join. Then gently bring the whole piece up to solder temperature and it will run.

    I know this is a larger piece than yours, but it shows the sequence;

    Click image for larger version. 

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Name:	11 Pallions in place for soldering.jpg 
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Name:	12 Bezel soldered to backplate.jpg 
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    James

  4. #4
    Join Date
    Jul 2014
    Posts
    383

    Default

    Thanks James & MMM (sorry I don't know your name!)

    I feel like the solder should have been okay, I use hard a lot for bezel walls and I did a bunch of ring shanks with no trouble only a few days ago. I use snips to feather the end of the strip and then cut pallions off. Admittedly I don't clean it a lot, but equally I never have, and to be sure I'll test some on some scrap.

    I still feel like it's something else tho... Could there be anything about the heating or speed of heating? My limited instinct thinks that's what it was, but I don't understand why...

    Thanks
    Faith

  5. #5
    Join Date
    Feb 2014
    Location
    Manchester
    Posts
    632

    Default

    I don't think quicker than normal heating would in itself prevent solder from flowing, provided the pieces being soldered remain at the critical heat long enough for the solder to melt and unite them.

    It sounds like either your solder was dirty, or the join between the two pieces wasn't inviting enough for the solder to flow down (either because the surfaces weren't clean enough or weren't tight enough) or one of the parts being soldered didn't remain at the critical heat for long enough, or your solder wasn't solder at all, but a stray piece of sterling.

  6. #6
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    8,851

    Default

    There you go Faith, let us know what happens when you try to melt some on a piece of scrap. If it won't flow, its a strip of sterling masquerading as solder, like Mark said. Dennis

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