Joining copper sheet

A friend is making a copper weather vane. Basically a silhouette, but with 2 sides, each of which will have some 3 dimensionality. The 2
sides need to be joined at the edges.
He is talking about brazing, but I feel that for the effort & cost, it is overkill and soft solder would be adequate and sooo much easier. I'm pretty sure that he does not have an acetylene torch, or access to one. MAPP/propylene yes.
Suggestions?
Thanks, Bob
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Bob Engelhardt wrote:

FWIW:
If there are more than one joint I would avoid soft solder: The heating of the piece becomes critical and I have nearly lost my marbles while soldering one joint with the other joints coming apart simultaneously. There may be other issues with exposing soft-solder joints to weather.
I have had good success silver soldering using MAPP gas only with a Bernzomatic torch. I use the lowest melting point alloy.
--
Michael Koblic
Campbell River, BC
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Michael Koblic wrote:

...
Wouldn't silver solder have the same problem with previous joints coming undone? Ideally you would have a progression of solders with decreasing melting points.
> There may be other issues with exposing soft-solder joints to weather.
Well, they use soft solder on copper gutters, or don't they?
Thanks, Bob
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Not in my experience. The heat conduction through copper is such that it is not difficult to achieve the 200-odd degC needed to melt the soft solder quite a distance away from the joint you are working on. It is much harder to do the same for a melting point of 600-odd degC. The heat tends to dissipate before it gets there unless the joints are *very* close together.

True, I think.
--
Michael Koblic
Campbell River, BC
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Michael Koblic wrote:

OK, I can see that. But, talking about heat being dissipated, is it hard to get large pieces of copper hot enough for silver solder? Oh, I guess MAPP would do a much better job than propane.
Thanks again, Bob
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Propane is plenty hot enough for most silver solder on copper. Have to use plenty of flux to keep the copper from oxidizing while it is hot. The biggest problem with heating for silver solder is keeping the copper from walking away from the heat. Any sheet form will warp and twist from uneven heating. Need to clamp it quite well.
The lower heat from leaded solder will not warp near as much. Again, lots of flux!
Paul
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KD7HB wrote:

Ah, yeah - warping. Soldering iron might be better in that respect.
Thanks, Bob
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Propane is plenty hot enough, but large copper pieces do require thinking. I like to use IFB ( insulating firebrick ) to surround the work. If it is really big two or more hand held propane torches may be required. If it is not too big, I will first heat the part away from where I want to silver braze. So that that part is not sucking heat away from where I need the heat.
You might consider SilFos. It is copper with some silver ( up to 15% ) and some phosphorous which makes it self fluxing. But sometimes I still use some flux. Silfos is no good on steel, but is good for copper. Should be available at welding supply or plumbing supply places.
Dan
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snipped-for-privacy@krl.org wrote: <snip>

Thanks - I kinda' remembered that there was a copper-specific braze.
Bob
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You will have less problems with warping regardless of whether you use soft solder or brazing, if you insulate the work as best you can and get the whole assembly hot.
Dan
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I have copper gutters, and they are soldered.
I have also had houses with soldered copper window pans in a bay window, intended for flowerpots, so watering the flowers wouldn't rot the wood.
Soldered copper is the traditional way to fabricate flashing for windows as well. Since the time of the Romans.
And weathervanes have been made of soldered copper sheet forever. Here the issue is making sure that the constant motion doesn't wear the bearings out too soon. A piece of brass soldered into the copper may be a good idea. I would also make sure that the vane cannot be lifted off the vertical pole by any reasonable storm wind. The definition of reasonable is whatever will cause the wing to fly away, probably 150 to 200 mph.
I would not worry about the durability of soldered copper, indoors or outdoors.
Joe Gwinn
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On Sat, 25 Jul 2009 13:12:44 -0700, Michael Koblic wrote:

You need a heat sink between the joint you're soldering and the previous joints. Maybe a couple of pieses of scrap copper, or even aluminum, clamped around the metal near the joint, to absorb the head and dissipate it before it melts the other joints.
Good Luck! Rich
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even a cold rag would do it
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"charlie" wrote: even a cold rag would do it ^^^^^^^^^^^^^^^^^^^ Or a wet rag at room temerature ;-)
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On Thu, 30 Jul 2009 09:14:23 -0700, Leo Lichtman wrote:

That's still cold, relative to the HAX. ;-)
Cheers! Rich
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I've assembled durable 3D shapes in copper by folding a flange over for mechanical strength before soldering.
Depending on his soldering experience an iron may be easier to control than a flame. Once for fun I duplicated the TIG pattern of overlapping circles on the soldered seams around some RF filter cans by moving the iron back and forth and watching the puddle.
It's all practice. I have been at it so long I can splice 0.015" solder end to end into rings with an iron. Try it!
jsw
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Jim Wilkins wrote:

Just doubled thickness:
| | | | | | |||| ||||
or having overlapping edges:
| | | | | | ------ | ''''''''
or seams: | | |____ | ____| | | _____| |_____
How did you handle the problem of previous joints coming undone when soldering the next?

What size iron are we talking about here? I have a old iron that's just a 1 lb hunk of copper & is heated over a torch. Never used it - how would it compare to 'lectric?

I think that I'll need a little more practice first <G>.
Thanks, Bob
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Bob, just as they say in the electronics trade, "Solder ain't glue".
Soft solder has virtually no tensile strenght, but is fairly strong in sheer. Hard solders are stronger, but still aren't intended to hold things together until after they cool completely; they are pretty weak when heated near-melting, but not quite.
Solder shouldn't provide the mechanical attachment; it strenghtens the joint, keeps it from moving after soldering, and keeps it sealed to the weather. The joint itself should be _mechanical_ in nature, and at least strongly-enough joined so that it will endure the forces of handing and fixturing during the soldering.
LLoyd
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On Jul 25, 9:11pm, "Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote:

Jus this afternoon, I was out in the garden and noticed that my wife had ponded some nails into a post and wrapped wire around them for a vine to climb on. I asked her about it, and she said she had done this a couple of years ago, with a roll of wire on my workbench.
It turns out that the wire was .020" flux core solder, and had been out in the elements for a couple of years, holding up a clematis with no ill effects. Given that bit of empirical data, I wouldn't hesitate to soft-solder a weathervane.
Also, if you apply the correct amount of heat, you really don't need to worry about adjacent joints. I, too, have amused myself by splicing solder. It's really not hard once you get the touch. .
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with
hesitate
There's no question that soft solder will withstand the elements, but I'll bet dollars to doughnuts that the 20-thou. solder was not "holding up a clematis". Rather, it provided a growth path along which the clematis vines found their own purchases along the way. 60- 40 Kester .020 electronics solder has a tensile strength of about 10lb, when virgin and not corroded. Still... it would take quite a length of vine to equal 10lb, so it might have been holding it up, at least until it reached another catch point.
(pretty stuff, that, especially on a walk-under arbor)
LLoyd
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