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Thread: Help with gaps

  1. #1
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    Default Help with gaps

    Hello,

    I made a pair of earrings for my only customer... my mum (also customer is being generous she pretty much takes anything I make she likes :P ) and I'm having some trouble with the pendant to go with it.

    I drilled holes and put copper wire through them through, soldered, cut and filed them down etc... However I get these hair line dips/gaps around the copper dots, which I tried using hard solder paste on but that didn't seem to make any noticeable difference at all. This was my first go with paste and it was hard to judge what it was doing but I'm worried that the solder just leaks through to the other side as I have some build up there, also that repeated heating is just making the gaps on the front worse, although there are still some on the back too). I wouldn't want to do more than one more try as I'm worried I'll make the silver too thin with all the repeated rubbing down (It got really bad firescale as well, I was sure I could see a little green man or maybe a saint in it) so if anyone has any suggestions I'd be really grateful.

    I've taken as close up as I can get might be able to blow it up a bit in photoshop if these aren't good enough.

    Click image for larger version. 

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  2. #2
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    Jun 2010
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    Default

    There's nothing like getting a really tight fit between components to avoid gaps. If necessary introduce very thin fillets of silver to fill hairline gaps. Failure to do perfect preparation usually results in failure of the whole piece for me.

    But in this case, I would be tempted try a rescue by fluxing over the whole thing, flood it with solder front and back (over the copper too) and sand it down again afterwards. Soldering it front-down and raised up a few millimetres (so you can get that heat underneath) will help a bit. Pulling the heat away slowly can sometimes leave the solder a bit proud - but often you get horrid firestain if you overheat. Usually the solder pulls away around any sort of gap but... you might get lucky.

    It's a pretty idea and well worth trying again even if this one doesn't work out!

  3. #3
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    Default

    Hi Kathryn,


    Joe has given you a rescue plan, but for the future you will find that strip solder is much more forgiving of small gaps than paste. So if you want to try a new and cheaper test piece I suggest you try it with a base metal such as brass, or gilding metal and copper wire first.

    Most of the holes which you made don't look bad at all, but the best method for a good fit is to make them first with a slightly smaller drill and then finish them by hand with the right size, held in a pin vice. A drop of oil helps too.

    I don’t know in which order you did things, but for the new test piece, if you distribute pallions of hard solder on the back quite generously, then as you heat the solder it will be drawn through to the other side to form a neat ring (meniscus) around each wire.

    Some of the benefit will be lost if you heat again to the same temperature, so use easy solder for your findings.
    Hope this helps, Dennis.
    Last edited by Dennis; 08-08-2011 at 09:57 PM.

  4. #4
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    Default [B]Rescue Plan B[/B]

    Good morning. As so often happens when you fall asleep with a problem on your mind, I woke up this morning with another solution.

    Provided that you can accept a frosted finish, rather like minute crystals, or coarse sandpaper, I suggest that you use a frosting wheel at low to medium speed on your motor. They are expensive for what they are, but offer a quick fix for closing any quite obvious defect or to decorate a boring area as an afterthought.

    You need eye protection against the possibility of an odd flying wire, and tie a wire or string through the finding at the back to hold it better. practice on a cheap off cut first, but don't worry too much about fingers as it does not hurt a lot if you accidentally graze them.

    The blue (medium) Frosting Wheel, Cooksons 999 CCQ, is at two o'clock in my picture, but they do end up at around £20 with VAT.

    Dennis.

  5. #5
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    Default

    Thanks so much for the helpful replies. Just for some clarification I did solder originally with strip using loads and the filing down, I wonder if part of the problem is the difficulty keeping the wire straight during soldering as none of the gaps actually go all the way through and are on different sides of the dots on back and front. I attempted to use the paste as a kind of filler which now seems like a silly idea.

    I'm not sure what you mean by leave the solder a bit proud? I think I need to do more reading to get some better knowledge of terms!

    I drilled the holes with a a bow drill straight to the same size as the wire so I will definitely try doing a size smaller but could you elaborate on what you mean by hand and using a pin vice (this is on my shopping list for next pay day!).

    I made earrings and the finish is kind of frosty as I used wire wool to get a scratchy matt finish so I could probably retrieve them and do the same. To be fair they had a small amount of the same problem but they were on a smaller scale and it was less noticable also as this is a second go I'd like to start working on perfecting the technique!

  6. #6
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    Well In that case, Kathryn I should definitely drill all the way through, keep the holes as tight as you can, sharpen the ends of the wire and pull it through a little way with pliers so that it jams in place. Then nip off most of the surplus and when they are all in, solder them. Dennis.

  7. #7
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    Quote Originally Posted by Dennis View Post
    Well In that case, Kathryn I should definitely drill all the way through, keep the holes as tight as you can, sharpen the ends of the wire and pull it through a little way with pliers so that it jams in place. Then nip off most of the surplus and when they are all in, solder them. Dennis.
    I'd have never thought of that despite accidentally having done it by selecting the wrong drill bit once!

  8. #8
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    Quote Originally Posted by Joe View Post
    There's nothing like getting a really tight fit between components to avoid gaps. If necessary introduce very thin fillets of silver to fill hairline gaps. Failure to do perfect preparation usually results in failure of the whole piece for me.

    But in this case, I would be tempted try a rescue by fluxing over the whole thing, flood it with solder front and back (over the copper too) and sand it down again afterwards. Soldering it front-down and raised up a few millimetres (so you can get that heat underneath) will help a bit. Pulling the heat away slowly can sometimes leave the solder a bit proud - but often you get horrid firestain if you overheat. Usually the solder pulls away around any sort of gap but... you might get lucky.

    It's a pretty idea and well worth trying again even if this one doesn't work out!
    I'm going to give this a go but I can't get my head round how I'll cover the front with solder while it is face down, I haven't got and wire mesh for soldering on but I'm planning on getting some would that work? How would I stop it soldering on to whatever it is sitting on? Also I think I'd need to use easy as the catch is soldered on with that, would that work for this method or should I de-solder the catch first?

  9. #9
    Join Date
    Jun 2010
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    So many questions!

    Solder mesh (wig)... I don't like them and don't use them.

    Propping... break a couple of bits off your soldering block, just by hand or saw it off (it's very soft). You've lots of room away from the copper spray for propping.

    Leave the catch alone, it should be fine.

    Paillons will adhere to borax flux even when upside down; equally paste is very sticky and will work in any orientation. But apply to BOTH sides... v. important! It will try to change sides and so you need to give it no excuse.

    Yes, easy is probably best for a rescue... I use it for these things with occasional success!

    I find that, if you pull the torch away very slowly after the solder melts, sometimes (now and again, unreliably) the solder will not sink back but remain proud ( salient, "sticking out")... but that much extra heating will usually stain my piece with oxidised copper.

    All that extra solder will leave a lot of cleaning up and a rather ugly colouring if you polish the piece; but the satin finish you show will be easy to re-establish and it is such a nice idea, it is worth a rescue.

    It is hard to fix a joint that was not accurately cut. It requires more skill to fix such a thing than would have been required to do it right first time. But I see pieces like this as little art-works and each is worth a bit of effort to save.

    The lesson though is to follow advice like Denis' and make very tight joints that do not need delicate and risky rework.

  10. #10
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    Thanks I understand it much better now! I'm definitely going to try using this copper dot idea for some other designs as well so hopfully I'll get it right first time next time and if my skill level makes the fix impossible I'll try a second one of these.

    I wish my teacher had mentioned drilling to a size below. I could probably do with saving up for a pendant motor as well. I've borrowed a dremel but I'm not sure that will be better than my bow drill.

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