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Silver soldering question

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benchmark:
I will give it a second shot in a darker room, thanks.

Dean W:

--- Quote from: HS93 on January 17, 2011, 08:13:36 AM ---Hopw big is the Boiler , it sounds like you are taking to long getting it hot with to small a flame, I would only use that torch on a mamod sized boiler and then I would proberley want a bit more heat to get it flowing.
peter

--- End quote ---

Hi Kenneth;
I think Peter may be on the right track.  The flux description in the ebay sale looks right for a proper brazing flux, which is what you need.  I don't know for sure though, since we don't have that brand here.  If Bogs or Stew come in, they can tell you the exact name of the flux you need, just so you can be sure of having the right thing.

If it takes the torch a very long time to heat your boiler, the flux may be pooping out before it gets a chance to flow the silver.  It takes more heat than you would think, since copper alloys draw the heat away so fast.  You don't always need so much of a higher temperature flame, but a larger volume of heat.  In other words, a larger burner.

Good luck with this, and hope you get it sorted out!

Dean

Jasonb:
Dean I have already said that the Easyflow flux shown will be fine provided that is what has been supplied, I use it myself

J

Stilldrillin:
Kenneth.
I too have the Maccmodels pack.  :thumbup:

First time ever was a (just) failure.  :bang:

Cleaned up. Tried again. With more heat....... Perfect!  :ddb: :ddb:

Not needed silver solder/ brazing since.  ::)



 "Good `ere, innit!" 

David D

cidrontmg:
Having done some silver soldering, I noticed some points that don't seem right.
First, that blow lamp seems far too small to do what you are attempting (soldering a boiler). It will be good for very small things, jewelry size.
Lack of heat is the most likely cause why your flux won't turn watery. If you are used to soft soldering, silver needs a completely different "attitude" to heating the workpiece(s). The workpiece(s) must be glowing dull, otherwise no go. And if they are copper, brass, bronze, they must be glowing at least some 1-2 cm away from the intended seam also. To get enough heat to even a small boiler will need a huge torch, if you donīt build yourself some sort of a brazing hearth. It doesnīt need to be anything fancy, one of mine is here. It's just 3 1/2 fire bricks. I have a bigger one, but it is seldom used. The hearth should not be bigger than needed to keep the workpieces "inside". It is rather essential for everything except very small things - so small that the flame is big enough to completely engulf the workpiece. Anything bigger will need the heat to be constrained somehow, or else you will need an enormous torch (maybe even two or three), and you'll risk setting the whole shop afire...


Thereīs also a drill press vise in the hearth to keep the workpiece in place (if needed). The vise is not used for anything else. For a pillar drill, it was rather ridiculous, but here it serves all OK.
For heat, I have a 14 kg gas bottle, with a Sievert burner, with various sizes of nozzles. And I also have a blow lamp similar to yours, for very small jobs   :dremel:
When you are silver soldering, the idea is to heat the clean workpieces quickly, so they won't have time to oxidize. First, warm it slowly until the (possible) water in the flux has evaporated, and then let go full blast. The workpiece should begin to glow in far less than 5 minutes, if it doesn't, there's not enough heat capacity in the burner. Point the flame to the biggest piece, the rest also gets heated on the side. Do not point the flame to the joint itself. When the workpiece is hot enough, the joint will also be.
Use as little solder as possible to get a completely sound joint. If you are feeding with a stick, you usually end up using way too much. If possible, put small pieces (or a loose ring, or small pallions) near the joint, and you can see when they melt, and get sucked in the joint by capillary force. When that happens, extinguish the flame, and let it cool. Do not heat it any longer than is needed.
The idea behind the "as little solder as possible" is not the price, although silver solder is far from cheap. But it is a real PITA to remove any excess solder. And if you don't remove it, it will look ugly... So if thereīs no excess to start with, will save a lot of time and swearing...
There's all sorts of tricks to make neat silver joints, and to keep it from spreading all over. Also the flux will tarnish the workpieces, so don't spread it all around the place. Liberally to just where it is needed, no more. But you will learn best by doing. It's not difficult at all, IMHO it's a lot easier than soft soldering, which I've also done quite a bit.
 :wave:

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