I made a silver jump ring bracelet a few months ago from 8 ga round
wire, and now want to make a similar one in gold. The silver one was
already too heavy for most people to consider comfortable, and the
gold required will be more than 2 oz making this a bit too
expensive. I would like to try making the jump rings out of karat
gold tubing to save some mass, but I’ve never tried it before. A few
preliminary attempts with base metal tubing predictably led to
collapse.
I’m aware there are many techniques for bending tubing (fill with
sand, wire, or low melting alloy, bend with tubing bending jig, heat
to low orange and then bend, etc) and I’ve seen Giacomo doing it in
his videos, and I was hoping to get some pointers from people who
have done this as where best to start. I was tentatively planning on
using seamless tubing from H & S, but I’m not against making my own
if it will give me better results.
I believe one of the techniques for making hollow gold jump rings is
to insert an aluminum wire in the tubing before bending it. After
the rings are cut apart, the aluminum is dissolved using common
household lye. Care must be taken while handling the lye as it is
very caustic. All traces of aluminum must be removed from the gold
tubing before the links are heated or they will become contaminated.
I’ve done it several times with a soft iron core. I first made the
tubing with an ID a little bigger than the diameter of the iron wire
which was then placed into the tube. The tube and core were then
pulled through the draw plate until the OD was right (the ID will
reduce until it reaches the core, and will then remain constant). At
this stage you can coil the tube to make the links and then place
them in fresh 10% H2SO4 (sulphuric acid) to dissolve the iron. It
takes along time - its faster if the acid is warm, but even then it
took a couple of days when I did it. When the iron is fully dissolved
you can remove the links and solder them up as normal.
I don’t make hollow jewelry myself but have seen tons of it come
across my bench. Most of what fits your size description is not
really tubing at all. You will see an open longitudinal seam inside
the links. I’ve seen them both cast and fabricated. My guess is that
fabricating this kind of thing takes some specialized tooling, but
that’s just a guess. Steven Brixner’s tip about the aluminum and lye
night work faster with such an open seam, but I’d wonder about the
seam staying closed during forming, something to tinker with.
Casting seems to me to be your better bet for a short run. I would
think a fairly wide opening inside the hollow would make pulling the
wax out of the mold a lot less frustrating. Or you could clamshell
two link halves together and solder, but you’d have an external
solder seam, which is done a lot so apparently some makers have no
prob with it.
Was the iron/sulfuric any better or worse than copper/nitric, or the
aluminum/lye mentioned by Steven? I would assume less fumes than
copper/nitric and more time, but I’ve never tried to dissolve
something out from inside such a relatively long narrow channel.
I didn’t know of the aluminium/lye method and really didn’t want to
use nitric acid at all. I experimented with the iron/sulphuric first
to prove that it worked. I was surprised at how long it took and,
since I don’t have a proper method of heating the acid, I had to
heat it in a microwave, put the links in until it cooled, then repeat
the process over and over. It did the job though.
Last night me and a buddy were screwing around in the studio and
tried a few things out. I filled an annealed tube of brass that was
crimped at one end with clean, dry, sand, and plugged the other end
with soft wax. I bent it around a dowel held in a vise, as I normally
would for heavy round wire, and it worked quite well. Unfortunately
it wasn’t good enough, and the cross section picked up a bit of off
axis oval that would make it quite hard to get the ends to match well
for soldering. In another attempt I took some chromatography grade
silica and tried the same method with worse results.
My buddy thought it would be clever to lube and insert hard iron
wire into silver tubing, bend it without drawing the tube down on to
it, trim the ends, and then unscrew the iron out like it was an
exotic bolt. Neat idea, but turned out to be quite difficult to get
the coils consistent enough for effective removal. Perhaps with some
more practice
I want to try out the iron wire/sulfuric and/or aluminum/lye
methods, but those really require gold to attempt and are a bit
outside my budget for the experimental stages.
Someone else pointed out we have some cerrobend, and I think that
might be the next thing to try. Has anyone run into any problems
removing cerrobend from gold?
Someone else pointed out we have some cerrobend, and I think that
might be the next thing to try. Has anyone run into any problems
removing cerrobend from gold?
Lube the inside of the tube with a mineral oil before putting
cerrobend in it or you can have some wetting of the gold or brass by
the cerrobend. If it wets the surface it is hard to remove.
This reminded me of something I tried a few months ago. I wanted to
bend some tubing and decided to use some Thermo-loc inside the tubing
(the thermo-plastic I use to mount jewellery in my vice for setting).
It was quite tricky rolling the stuff into the required sized sausage
shapes to insert into the holes, but I managed it and the tubing bent
nicely, without distorting. Removal was easy afterwards by dunking
the tubing in hot water then grabbing one end of the thermo-plastic.
However, I only wanted semi-circular pieces and so removal was no
doubt easier than it would be if you wanted the complete loop - as is
obviously the case with making tubular jump rings.
As far as you microwaving of the acid goes, I may have a suggestion.
You can heat metal in microwave ovens as long as the metal is
completely submerged in liquid. You should be able to put your jump
rings in the acid in the microwave all together without any ill
effects. I would, of course, be very careful and test it out with
small amounts of metal and acid first.
While I’ve never tried anything like this in a home microwave, I’m a
chemist by trade, and we often use microwave reactors. The addition
of a teflon coated metal magnetic stirbar is common, and many
reactions use metallic catalysts including palladium and palladium
salts. The only issues are when any solid salt or polar material is
outside of the liquid. If crystals get stuck to the side of the
glass vessel above the solvent they can then superheat.
I think that this was covered after a fashion in the discussions
about melting metal in home microwave ovens.
I don't believe that lye would effect either brass or silver
tubing.
Good point, I grab some aluminum (I don’t think there is any at the
studio) and try it out this week. Does it matter how concentrated
the lye solution is? Should I heat and agitate it?
One way of bending tube is to fill it with ice. I assume that it
would work down to jump ring size but you would probably have to be
quick doing the bending. This method is used in making trumpets etc.
by some companies and has the advantage that the ice just melts away
leaving clean metal. - one interesting video is here
One way of bending tube is to fill it with ice. I assume that it
would work down to jump ring size but you would probably have to
be quick doing the bending. This method is used in making trumpets
etc. by some companies and has the advantage that the ice just
melts away leaving clean metal. - one interesting video is here
http://www.youtube.com/watch?v=Yl8qfu-ojTQ
Wow, what a great video! Soap in the water - I wondered how the ice
was kept from shattering when tubing is bent.