We are using the jewellery torches with LPG. While soldering some of
the pieces are got melted, Due to the over heat.
Is it available any innovative torches available with heat
controller? Please give a solution.
thanks & regards,
Most jewelry torches are VERY SMALL orifice tips so that the
flame/heat is very concentrated and small. These torches are very
good for higher caret gold work as gold as a person can get in to the
work area, heat it fast and solder and get out without heating the
entire piece as would occur with a bigger torch tip/flame. Silver
work requires the entire piece be heated so a larger tip/flame is
usually used but too big of a tip/flame will easily allow the user to
melt the work. The smallest oxy/LPG tips that come with "standard"
welding equipment are too big for fine work. Jewelry welding
equipment is much smaller both for access to the work but for less
"total" BTU input but not lowering the actual temperature of the
flame. Here is the URL for just one site showing some "Smith Little
Torch" units. I think this is what you need to have far better
control or heat input into the work.
I ams sure others will chime in on this, and some will have other
ideas and thoughts, which is great as it will give you a choice of
what direction you might want to take.
It sounds like you're trying to limit the maximum heat in your
working piece, and as John explained you might not want your torch to
be cooler (since you still want to do the hot work as quickly as
possible, minimizing oxidation etc).
So you could try to arrange a non-contact thermometer, the IR-laser
types tend to be built with two different focus lengths and you might
be able to get pretty quick feedback although most of them take
1-2seconds to register a temperature and you'd probably have to keep
the work piece clamped with the thermo also clamped and aimed
accordingly, but that approach seems error-prone. Probably better to
accept a couple failures while paying really close attention. Perhaps
some old-timers have some analog tricks such as a burn-away material
next to the piece. The problem seems similar to forging aluminum in a
coal or gas forge.
If you're trying to speed up the work, you might pre-heat the work
pieces on a warming plate (non-critical). Anything that normalizes
your process (ie gives you the same amount of time under torch no
matter whether it is summer or winter), might help"you can count to
the same number eachtime once you put your torch on the piece. And of
course a smaller burner/tip might help save some fuel along the way.
You can control the amount of heat by the tip size and the size of
the flame. Are you using LPG with oxygen? I use both an Acetylene /
Air torch and a Propane / Oxygen torch. The Acetylene / Air torch
produces a much cooler flame.
Select the right size tip for the job. Too large of a tip will heat
the piece too quickly to the melting point. Remember that most of the
piece needs to be heated to the point of melting the solder so using
too small of a tip may heat the smaller part being soldered past the
melting point before the larger part gets hard enough.
No matter what you use you also need to practice, practice, and
practice some more until you get the feel for when the piece is
getting too hot.
Learn to judge the temperature of the piece by its color. There are
lots of good books that teach good soldering techniques. After a
while you will be able to tell when you are in the danger zone.
Most common mistake when soldering is not using large bushy flame
when heating silver, heating whole piece, then focusing on when
solder is whem temp is close to solder melting. Blue cone, too hot.
It is not equipment, learning to have control of heat with torch
knobs. Sometimes I heat whole piece and then make flame much hotter
to localize heat to get solder to flow.
Gold much different, can use hotter flame and heat local area when
soldering, care to not have flame too hot and melt gold before solder
flows if design is delicate.