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Prevent doming


#1

Hi!

I’m curious as to how different folks would handle a fairly standard
job: soldering thin sheet to thick sheet. Today’s example happens to
be:

White gold: 0.30 mm.
Oval length: 2.5 cm.

What are the various Orchidian techniques for preventing it from
slightly doming when it cools? I usually use powdered solder fully
sweated on one of the sheets before joining the two layers. I get it
to flow over the entire surface and then sand lightly. [If either of
the layers had piercing (allowing the hot air to escape), I would
just put paillions around the edges.] My colleague puts a heavy
steel weight on it after the final soldering, but I find that does
not work very well on small (jewelry-sized) pieces (he usually does
big stuff). How do YOU balance out the opposing
expansion/contraction rates?

Janet in Jerusalem


#2

A line was missing from my last post (preventing doming when sweat
soldering sheet). Should read:

Sterling: 1.00 mm.
White gold: 0.30 mm.
Oval length: 2.5 cm.

Janet in Jerusalem


#3

Janet - I don’t have a problem with doming. What I do different from
your description is this:

Coat the thin piece lightly with paste flux. Let it dry to slightly
tacky.

Sprinkle on powdered solder, not too much. Don’t heat it yet.
Situate the thin piece on the heavier one, perhaps securing it with
stitches. Heat from the underside of the thick piece. After solder
flows, cool slowly. I don’t use a block on top.

Judy Hoch


#4
If either of the layers had piercing (allowing the hot air to
escape), I would just put paillions around the edges.

Janet, do you mean you put pallions of solder around the edges of
each piercing, or just around the edge of the whole piece?

Janet (Another JB, but in Canada!)


#5

Hi Janet, If both pieces of metal are annealed and not flexed at
all, you won’t usually won’t get doming. Anneal the plates after
they are cut tosize by putting each plate on a flat piece of
charcoal, get red hot and push down with a flat piece of steel. Let
me know how it works out. have fun. tom


#6

I should have asked if you could flatten the soldered pieces between
two steel plates after the doming occurs. tom


#7

What if you tap it flat after pickling on a steel block with rawhide
or a plastic mallet.


#8

Hi Janet,

Ted here in UK, what your making is in fact a double’ material which
has metals with differential rates of expansion and contraction. you
may know this effect is used in bi metallic thermoucouples.

In your case the thicker layer is pulling the thinner one. result
doming, as you describe, well, to putit at its simplest the thicker
layer is softer, so why not just do what I do is just hammer it
flat. Try it. youll find it will work. All you will be doing is
stretching the softer one.!! cant be simpler.

Obviously use a leather or similar soft faced hammer on a slightly
concave steel block to push it down. As you should know, metals have
a yield point beyond their springyness. You need to achieve this
yield point to move the metal to where you want it.

Ted Who does all metal moving work, ie wrought.

To give you an example one of my minting dies is for a flat key fob
for the little firm from Stuttgart (Mecedes), Nothing to do with them
I may add, just my product. this mints flat but I want it seriously
domed to make it into a button (sterling of course) A suitable piece
of 1in bar, turned to the right profile and a doming block with a
concave depression to match. Then its just a simple hammer job, prior
to fitting/silver brazing of course the back with the omega button
loop to make a hollow button. Front in 1mm silver back.75mm Dont be
afraid to hit it!! Very few on this forum do wrought work, its so
easy and fast.

Let me know how you get on.
Ted.


#9
If either of the layers had piercing (allowing the hot air to
escape), I would just put paillions around the edges. 

Janet, do you mean you put pallions of solder around the edges of
each piercing, or just around the edge of the whole piece?

Janet (Another JB, but in Canada!)
Around the edges of the whole piece.
Janet in Jerusalem


#10

Hello,

I don’t know what the two pieces you are trying to solder without
doming look like, but I just watched a short vid by Ronda Coryell on
a subject that seems pertinent. She packed the inside of a box clasp
with Kate Wolf’s Soldering Clay available from Rio Grande Easy to
use this material and it washes out after the soldering operation.
It prevented the box from warping or doming.

Also, it helps to anneal the pieces to be joined, so that they don’t
expand and contract differently while soldering.

Hope this is useful,
Linda