Soldering weeny things...?

[Faith]

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

[MMM Jewellery]

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

[Goldsmith]

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;

951195129513

James

[Faith]

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

[Aurarius]

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.

[Dennis]

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

[enigma]

Could it be to do with the angle you heated at ? particularly if using tube? Did you heat from underneath?

[Faith]

Thanks all,

So taking Marks advice first, it's definitely solder, it has a bit of masking tape on it (at the unused end) labelling it as solder, it lives in the solder drawer and I've used that exact bit a lot recently. It could have been dirty, but after ruining it, I did have one more desperation go, with a new bit of the same solder, a lot of flux and turned my torch way down (it's only a baby butane hand torch) and that time it flowed. It didn't flow well, the piece was all oxidised and dirty by then, but it did flow. I also think the join was okay, the tube was filed flush with mitre jig, then emeried on steel block, as was the sheet. Apart from that it was just sat on it with gravity - as I would for a bezel wall.

Perhaps i was heating it so fast the two parts weren't ever at the same temp at same time?

Finally Sarah, yes I did heat from underneath for all attempts. That's what I'd normally do, I assume the same is true for tube?

Faith

[enigma]

Yes I would heat mostly from underneath although would also run the torch around a couple of times on top when it was close to flowing point.

[Dennis]

The item is so small, faith and you know what to do, so slight changes in technique will not make a difference.

My second bet is that you have either run low on gas, which makes the flame too cool, or the opposite: that you had too fierce a flame , directed on one part and not the other.

But one important piece of the puzzle is still missing: did it melt fine, tried on a piece of scrap? Dennis.

[Faith]

Hi Dennis,

Yes it did, just tested the solder on scrap and its all good and melty. Then I tried a new bit of sheet and chenier, I may have gone overboard on the flux and I used a smaller flame, and it flowed fine. I can't see a great meniscus inside the tube mind, but it's only 2.5mm in there so would I expect to? I did everything I could to heat the middle but still no obvious line of solder inside. Reckon it's okay?

Thanks Faith :)

PS - post pickle I wonder if I can see the faintest shimmer of a line inside, of course that may be my hopeful eye. I'll probably carry on anyway, soldering the shank on is usually where the wheels come of the wagon anway!

[Dennis]

If you can see a continuous solder line around the outside of the tube, then that's it Faith. Dennis.

[Faith]

Thanks Dennis,

You were right, it filed down fine and seems solid. Even got the shank on trauma free (but I think little settings might be easier in that respect than bigger ones). Got this far today:

9521

Which reminds me I have SLR photos of the last one that I've still not edited!

Ta again :)
Faith

[Aurarius]

Well done for succeeding with that.

I'm not sure I really understand the need for "trying to solder a little piece of sterling tube...to a little piece of sheet" in this case. If your intention was to solder the setting on to the shank (rather than inset it) could you not have filed a scoop out of the bottom (and still open) end of the tube, and soldered it straight on to the shank? You'd have reduced the number of solder joints and probably got a firmer fixing between setting and shank.

[Faith]

Hi Aurarius,

Thanks :) So this ring is to go with the stacking set I've been making myself:

9522

It'll be the smallest stone, hence trying a tube set rather than trying to make a bezel cup that small. But I wanted it to look like the others, with a flat closed back and slightly tapered base to the setting, and for the rings to sit together, all the bezel bases have to sit clear of the neighbouring shanks. Even filing the normal flat spot on a shank interferes with the interlocking, so now I just use lots and lots of solder to try to get a good join. I've been wearing the others every day for a few months now and caught them on things and they haven't fallen off yet. *touch wood*.

Thanks for the idea though, for other rings that's a really good option :)

Faith