i make hammered bronze bangles of 8ga wire, joints often break during forging. started out using hard silver solder, then tried medium. would brazing rod be better?
Hi,
intetesting…as a side note…what about an alternative connection…a design element…like a hook and eye loop?…or leather wrapped ends (glued)with a gap that ties…or…open ends with caps of some kind…or where the ends that are soldered are not forged…
julie
2 Likes
Why not use bronze solder? I bought some from RioGrande a few years back for bronze bangles. It’s not a perfect match to the metal, but it is pretty close. I never had any issues forming the bangles on a mandrel. I’m always careful not to hit directly on the seam.
2 Likes
i have tried that as well . this design needs extensive hammer work to achieve the chunky and sculptured look i’m after. this question is not so much about color-rather strength
1 Like
thanks Julie, i am wedded to this design. i do get them finally to stay but it often requires a bunch of solder and multiple tries. maybe i should be annealing more frequently ?
2 Likes
My brother and I have made a lot of cuffs in sterling over the years. Silver soldered butt joints take a little learning but for us they are a staple to what we do. I am aware that cuffs and bangles are different beasts and brass, bronze, and copper are each a separate learning curve.
I was wondering if you have tried soldering a “Scarf” joint for your connection? I normally used these working on wooden boats. But the science is the same applied to metals. Carful surface prep and you have a solder joint that is three times longer than the diameter of the wire. This should take the hammering you are describing.
Don Meixner
5 Likes
Hi,
ah, annealing…good point…the forging builds up alot of tension…
…what does the broken join look like?…
julie
1 Like
Do your joints come apart while you are forging the bangle around a mandrel? Or when you are expanding the bangle while driving it onto a tapered mandrel? Either way I think the idea of more annealing is a good one.(Says the man who has never worked with bronze.)
My experience with brass doing similar work has been I have better results with silver solder than with the solder sold for brass. Also I tend to over heat the brass and burn it if I don’t hit it with the solder at just the right moment.
I guess that it is time to look into this with a bit more effort on my part. Photos of your work might help.
Don
2 Likes
1 Like
**DE2198B9-033F-48BE-8587-60F39A17A72F.jpg i have used hard, & medium silver solder. also tried bronze. end up using a big glob of medium silver solder, but then i have a messy joint
Scarf joint - I was picturing this before you used the terminology, Don.
Julie, I hope you try this suggestion and report back on it. Having a larger join (longer) sounds like an excellent solution. I’ll experiment with my copper bangles since sometimes I have joint failure when shaping in the hydraulic press. And if the stress is spread out it seems it would have more chance of success.
1 Like
Hi,
what does the failed joint look like?
-
does it look like it popped open (ie: join surfaces look like what they did before you soldered?…smooth?…
-
or does the failed joint look like it “tore”…more jagged…kinda porous surface?
the reason i ask is that in my experience, when i get #1, i feel that the solder did not fully fuse “into” the 2 sides…a third alloy is created at the solder joint…not hot enough, not long enough…
(solder combines with the metal that the piece is made of, kind of like water seeping into a sponge…but not…maybe more like creamer mixing with coffee…or like how separate ingredients in a brownie mix become a different composition when baked…the brownie…once they are mixed they become something else…no longer separate ingredients)
and when i get #2, the metal failed, rather than the solder joint…or the third alloy failed…like…if you try to physically peel apart 2 pieces of soldered sterling silver, the metal will often fail before the joint…
…i hope my non- technical explanation makes sense…others may have more intelligent comments!…
julie
bronze bangles.pdf (410.4 KB)
yes, like it popped open—
Hi,
ok, hmm…maybe you need to keep the heat on the joint a few seconds longer after the solder flows…maybe you are pulling off too soon…
also make sure your joints are tight…no gaps at all…
solder may bridge a gap, but it is not like glue…it needs to penetrate the metal…the surface of the metal, at the interface, melts…and the solder combines with the sterling/ brass…and then i “think” the solder mixes with the surface metal and the melting point is lowered right there and it melds together…i may be mis-speaking…i need to go look it up in brephol book…
maybe someone here can explain this phenomena better…
bottom line, if joint is not soldered completely, then the solder is just laying on the surface, acting more like glue…and the joint is not fully soldered…and it may pop open…
perhaps as an exercise, solder a bangle, and then twist the ends with pliers and see if it pops open…
this article kinda talks about what i am trying to say…
here is another article…talks about using enough flux…if the flux gets “spent” oxidation can occur and lead to a weak joint…
julie
(I tried to edit my above post, but i timed out…see below revised)
https://www.amazon.com/Theory-Practice-Goldsmithing-Erhard-Brepohl/dp/0961598492
julie
Hi,
and in terms of “work fit”
in the book “Jewelry Concepts and Technology”
by Oppi Untracht, page 405,
he mentions that in terms of fit, “the distance between parts should be minimal to create a condition favorable to capillarity or solder flow. If spaces are too wide, capillary attraction is weakened because the power of gravity acts against solder flow.”
…and then, there is the topic of metal cleanliness and fluxes…and the “why’s” of how it affects the soldering process and solder flow…
great book, i highly recommend Amazon.com: Jewelry Concepts & Technology eBook : Untracht, Oppi: Kindle Store
julie
1 Like
Hi,
so, with the above in mind, regarding parent alloy and solder alloy creating a third alloy, there is also the consideration that:
sterling is 92.5% silver/ 7.5% copper…
brass is usually 85% copper/ 15% zinc…
and bronze is 85% copper/ 15% tin…
and hard plumb silver solder is 75% silver/ plus zinc and other proprietary elements…
so brass and solder both have more zinc than sterling silver…
and zinc burns off at a lower tempurature…it has a very low boiling point…
which might be causing your joint alloy composition to become brittle…porous…
a lot goes on in the soldering process…
keep an eye on your flux as well…the flux i use turns green when it becomes “spent” and saturated with oxygen…
also, flux turns glassy, and can “hold” pieces together, appearing soldered…only to loosen- come apart after pickling dissolves the flux…
someone may have better feedback on this…
the oppi untracht and erhard brepohl books are pricey, but well worth the price for all the detailed content they contain…they both cover, in detail, what other, more compact books do not…they cover the same broad topics, but they each cover different things, in detail…i highly recommend!
julie
Bronze alloys have different chemical compositions depending on purpose. Jewerly bronze is 90% copper, 10% tin or a higher amount of copper and less tin. 15-20% or higher zinc is technically a brass. Having worked with mixed metals, bronze and brass are much more difficult to work with than silver or copper. The zinc content makes brass work harden much faster than either copper or silver. The same applies to the tin content of bronze…Frequent annealing, first air cooled to avoid thermal shock, then quenched. High silver (Stay Brite) content silver solder with well made joints will resist breakage as they are more ductile. Another alternative to solder is bronze brazing rods. These have a more yellow color than low zinc bronze. The high zinc content makes brazing rods a brass.
1 Like