Using Tig Torch to Silver Solder

[dsage]

I had a strange idea that maybe I could silver solder using a TIG torch as the heat source. Has anyone ever done this?
Why: Because I don't really want to heat the whole part with a big torch and I don't have a pencil torch of any sort much less one that could apply enough heat to a small area quickly on a heavy(ish) section.
The idea was that I'd apply the solder flux as usual in the joint and set the TIG torch down low enough to NOT melt the parent metal but high enough to melt the silver solder which would either be fed in or placed in position. The TIG would be applied long enough for the solder to flow into the joint.
I thought this might be useful for items whch don't need to be welded per-se. Perhaps heavy sections and things like but pieces that if welded would need to be cut back and filled or welded from all sides. Instead the silver solder would flow into the joint.

What do you people think of this idea?

Sage

[Geof]

I doubt that it would work because silver soldering is so susceptible to overheating. I have done a lot of silver soldering and in my experience you need a soft diffuse flame. I have never been able to silver solder in the same manner as you can do bronze welding with a hot flame that you traverse back and forth over the welding zone to get rapid localized heating. When I have tried this to do silver soldering this way the surfaces I was soldering nearly always overheated and burnt so the silver solder would not flow and the silver solder overheated and just flowed away because it gets so liquid.

[mfgbydesign]

"silver soldering" is a brazing operation, which uses capillary action to draw the filler material into a small gap between the two pieces to be joined. Frequently used for joining dissimilar metals that otherwise cannot be welded. The proper way to perform this operation is to heat a large area of the workpiece and when the proper temperature is obtained (as indicated by flux color, base metal color, oven temperature plus soak time, temp. sticks, etc.), while heat is still being applied, filer metal is fed FROM THE OPPOSITE SIDE OF THE JOINT to be properly performed. Using a "TIG" (GTAW) torch provides a concentrated heat source and is intended for welding a localized area with a small heat-affected zone. Merely heating the filler metal and applying it to the joint results in a cold fill and will not penetrate. Filler metal must be evident on both sides of the joint with a smooth fillet.

[packrat]

dsage- does it have to be silver solder? If your just looking for a fairly low temp filler metal to join metal with, to keep distortion to a minimum, look into 'silicon bronze'. Silicon bronze is a regular Tig filler rod that works well and is not a brazing rod.

[dsage]

No, it doesn't have to be silver solder but that's what I have around. I'll have to look into this some more. I'll try the silicon bronze. I assume that would be available at a welders supply. As far as the silver solder goes, I wasn't intending to apply heat directly to it directly like filler rod. I was going to apply heat along side (or otherwise away from) the point of solder application until the metal is the correct temp for the solder to flow like it would be if the whole piece were heated. I understand all of the issues mentioned. I guess I'll have to try it to see if I can actually DO what I'm proposing.

Thanks for the ideas

Sage

[donmorris]

I have been doing this for years with great results,,, but as several people said it is not really the same as a torch.
I use it to repair copper components and several other things.
For example something arced on the copper tubes and there are pinholes,,,it is very simple to repair these pinholes with the tig with very little heat.
I have filled in "arc blow holes" in transformer copper mounting plates in an emergency,,, they would be down for days unless I could pull this off,, it seemed to work and you could not do it with a torch,,,to much heat
try it,,, it is easy to learn and great for "certain" jobs
The silver solder I'm talking about melts at 1200f or a little higher,,,so it is more brazing than soldering.