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Soldering - Trouble getting an air-tight fit in joints


#1

I’ve been using recycled sterling lately to forge/fabricate
components needed in some of my designs. Many pieces I use I’ve had
to hammer, cut, file, etc. for their use. When I’ve needed to solder
the joints of thinner pieces and pieces of hammered out silver pieces
(ex. recycled rings, thicker wire), I seem incapable of getting
airtight joints. Very frustrating. I have tried various methods to
get good joints: cutting the two ends together with a thin-cut wheel
on my rotary tool; filing the ends to correct the bad fit (I
attempted this with no success after some hours of doing everything
that should work), etc.

Believe it or not, I’m quite capable in soldering techniques. These
pieces are uneven in thickness (I don’t own a mill) sometimes, but
that shouldn’t be such a problem. I’m looking for ideas & tips.

Thank you


#2

If you just can’t seem to create a perfect joint freehand, you might
want to buy a miter cutting jig. It’s a nice little hand vise that
allows you to clamp your piece of metal in the vise and then file a
precise miter, then you have a perfect joint. Another method is to
get your joint as close as you can, solder it if needed to hold it
in position, then saw thru the joint to create a perfect a joint
without gaps, then resolder.

http://www.ganoksin.com/gnkurl/ep7zg2


#3

There are no universal instructions on how to get airtight joints.
Every situation requires it’s own approach. What can be said is that
good fit is largely depends on planning rather than on the
execution.

Goldsmith must think through all the steps of fabrication and have
clear idea of how various problems will be solved. All this must done
before the first fingerprint will be deposited on metal. For specific
examples check out my DVDs. Each one deals with different situations
of obtaining precise fit, but the general theme is that fit is a
natural outcome of the method of fabrication. The mistake is first to
fabricate and than try to fit it together. It will fail every time.

Leonid Surpin
www.studioarete.com


#4

Be sure things are really, really clean. put the heat to the thicker
piece, not at/on the solder. Be sure things are absolutely clean.
Use fire scale (alcohol mixed with borax - burn off the alcohol or
let it evaporate. Solder immediately, again putting the heat to the
heavier lice and letting the heat travel to the thin piece. We like
cut solder but paste if you must.

You might try doing some “test” soldering on scrap so you don’t ruin
your work.

Good luck
john dach


#5

Saw through an intended join don’t use a cut-off wheel- the kerf is
too large. But more importantly you should insure that the scrap is
all sterling, then melt and pour an ingot, rod, etc. then roll out
or forge the material and work from your own sheet,draw your own
wire etc… A good join requires measuring exactly and then fitting
exactly- solder isn’t designed to fill gaps. As far as “airtight
joins” i’m not certain what you mean unless you are joining hollow
constructed pieces…If it isn’t fitting right, melt the solder and
soak it up with braid or a desoldering tool, and try again.Too much
flux, or too much solder can cause problems.If using paillions
thin them somewhat before placing in or on the fluxed join.If you
are inexperienced try a flux that “indicates” temperature ( becomes
clear at “x” degrees indicating about 1100degrees F, close to the
melt/flow point of many solder types…invest in some calipers and a
good ruler with mm markings so that your joins are exacting and fit
precisely every way they can be measured…rer


#6

Leonid’s reply has the soundest principles to follow. My solution to
precise fits for soldering is as follows.

I make many hundreds of such joints each year.

Rings I make by the 50 off. After all the preparatory metal work,
plaiting twisting forging annealing etc, Ive wound the yard strip
onto a tapered steel for all the differnt sizes I need.

Then parted off with a HSS circular saw, When trued up then I use a
1in wide vertical running linishing belt of 300 grit in the gap.
press together. turn through 180 deg and repeat. I have then
perfectly true parallel faces.

Then I use a spring loaded jig to support the ring at the brazing
station. Using brazing foil in the joint and fluxed all over then
heat.

The springs close the gap as the ring heats up.

Perfect joint each time.

You may need several jigs of different sizes and and spring loading
for different thickness of work.

The biggest I have is for circular bangles some 1/2in wide and 1/4in
thick. How you make the jig is up to you.

These joints will stand subsequent forging and or rolling between
dies. The above technique is for me the only way to line up the 18
ends of a 9 wire plaited celtic ring and braze up accurately.

Its really only an engineering solution to a metal working problem. A
few hand tools at a jewellers bench really arnt enough for
profitable production work.


#7

Erin, what do you mean by airtight joints? OK Erin you can solder so
this is not a newbie post to you. But newbies pay close attention.

Here are some tips that may be useful or not. But on this site we
post to try and help and eventually someone solves your problem. THIS
IS WHAT MAKES THIS SITE SO USEFUL, YOU CAN GET FIFTY POSTS THAT DON’T
QUITE SOLVE YOUR PROBLEM THEN ONE THAT DOES - REALLY MAGIC!

I use this to solder very heavily reticulated sterling silver rings,
so I am used to uneven metal thicknesses. Note I use one of those
"big" silver smith torches that run on LPG and air through a foot
bellows. WTF or LOL you say. But I have very little oxide build up,
by using this torch. Note oxide is not firescale. Oxide is removed
in pickle firescale is NOT. Now I don’t wont to start a million posts
on firescale here. But firescale is oxygen trapped under the fine
silver layer left after pickling. Firescale must be physically
removed by sanding etc.

NOTE I AM WRITING ABOUT A RING, MODIFY FOR OTHER APPLICATIONS.

1 File the ends to be soldered, to get them flat.

2 Put the ends together.

3 For a ring anneal the piece, lights out/dimmed so you can see the
subtle colour change, to deep cherry red. This is very important
because you may have work hardened the silver and if you solder at
this point you may “relax” the silver and it can move apart at the
join REMEMBER I AM TALKING ABOUT A RING. If you go beyond deep
cherry red welcome to excess firescale.

4 Cut vertically through the join with your jewellery saw. If not a
ring get joins as flat and smooth as possible by filing and sanding.
OK you seem to be doing this.

5 Hold up to the light, if you CAN’T see light through the join you
are ready to solder. Works with all solder joins not just rings. If
you can see light, work on the join till you can’t see light. Solder
DOES NOT FILL GAPS. IT FLOWS IN JOINS BY CAPILLARY ACTION. Maybe you
should use binding wire if possible.

6 Lots of flux.

7 Warm the whole piece with a big yellow/gentle flame.

8 Concentrate the flame on where you want the solder to flow to in
the join and heat till the solder flows.

9 Pull the flame away momentarily, then reheat till the solder
gleams/ shines. Pull the flame away as soon as it gleams.

10 For the first solder on a piece start with hard solder.
Subsequent solders go to medium then easy.

NOW BELIEVE IT OR NOT. Once soldered with hard the soldered joint
will flow at a slightly higher temperature than hard that has NOT
been balled up on a pick. You use a paillion/piece of solder on the
join for the second hard solder. Try this first time on a piece your
are prepared to have go wrong it probably will. This can be as much
fun as learning to bright cut bezels. So if you use this method you
get 6 solder temperatures not 3.

Hope this can be of some use, if not email me some more details.
TTFN
Richard


#8

The mistake is first to fabricate and than try to fit it together.
It will fail every time

Leonid is right, I have try it, to many times!