Silver soldering set up

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FRED DADDI
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Silver soldering set up

Post by FRED DADDI »

My silver soldering facilities or technique are both lacking. I have some refractory brick and Acetylene and some propane torches. For the moment I am doing the ends of piping which I guess are compression type fittings available from the trade in the uk. Any photos or suggestions for a set up for this are appreciated. I think i need a pickle tank or jar and need some pointers on where to go for acid and what most folks use for this type work again any pointers are appreciated


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Builder01
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Re: Silver soldering set up

Post by Builder01 »

If you are just doing cone fittings on copper pipe, a small propane torch will give you enough heat. Put flux on both the pipe end and the inside of the cone. Push the cone onto the pipe. The fitting should not be too tight of a fit on the pipe, you want a little space for the silver solder. Play the flame on just the coper pipe, if you overheat the brass cone, you will melt it. Propane will not melt copper, it is not hot enough for that. You can place the pipe/cone in a vice with the pipe pointing up, of course don't crush the pipe, just tight enough to hold the pipe upright. The vice will act as a heat sink, so get the pipe sticking out of the vice as far as possible. When the copper is hot enough, the solder will flow up into the space between the cone fitting and the pipe by capillary action. The pipe needs to be really hot, much hotter than soft solder. Do not play the flame on the silver solder that you feed into the joint as you will melt it before it gets into the joint. The copper needs to be hot enough to melt the solder, dip a little flux on the end of the solder too.

Do not quench your assembly, you can crack the solder. After it cools down, I use citric acid to clean things up. You can get it at Walmart in the canning section of the store, or, really cheap on Ebay. I have some mixed up in a plastic coffee can to clean small projects like what you are doing. For big projects, like a copper boiler, I have some mixed up in a large plastic tub.

Also don't forget to put the nuts on the pipe before you solder the second cone onto the pipe!

David
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NP317
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Re: Silver soldering set up

Post by NP317 »

Yes, white vinegar works fine for a slow controlled cleaning of silver soldered items.
It is available from the grocery store in one gallon plastic jugs, and smaller sizes.
I let them soak overnight, with a brushing the next morning. Then additional soaking time if required.
Simply rinse off with warm water.
Gentle and effective, and organic too.

Kozo Hiraoko's books on locomotive construction contain good lessons on silver brazing. Worth the study.
They helped me get it done correctly, with few screw-ups.
RussN
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Builder01
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Re: Silver soldering set up

Post by Builder01 »

Vinegar is actually made of acetic acid, not to be confused with citric acid. Citric acid is purchased usually as a powder and is mixed with water. It is a bit more aggressive than vinegar and yet it still quite user friendly. I scrub my parts with a brass brush to get the last bits of oxidation off.

Yes. I too, recommend Kozo's books, especially the one on the 0-4-0

David
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Fender
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Re: Silver soldering set up

Post by Fender »

It’s very important to get any oxidation and all traces of oil off of the parts before fluxing and heating. Usually a scrubbing with fine sandpaper followed by detergent and warm water, then a rinse will suffice. To keep the solder from spreading where you don’t want it to go, mark the boundary with a magic marker or pencil.
Dan Watson
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Greg_Lewis
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Re: Silver soldering set up

Post by Greg_Lewis »

I find the black flux works better for me than the white stuff. The former seems to have a greater temperature range.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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Chris Hollands
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Re: Silver soldering set up

Post by Chris Hollands »

My experience with silver solder is - one day you can be rock star and silver solder the space shuttle in a day , the next time you don't know what you are doing wrong the stuff just wont flow .
Patience is the big one don't rush - spotlessly clean and make sure the item can not move when you go to touch the item with solder eg - parts fall over or come apart if it does and we have all done it you have to start all over again as the solder just does not seem to flow after that - dirt /overheating etc .
I also notice the old cadmium 45 s/s flows better than the cad free and cad free seems a bit higher temp before it will melts .
I just ran out of the old cadmium stuff , i sort of kept it for those special jobs or very small items it just seems to be better/easier to use .
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Greg_Lewis
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Re: Silver soldering set up

Post by Greg_Lewis »

I agree with Chris that the cadmium alloy flows better. It's available from McMaster but you need a thick wallet.

Also I'd add that placing snippets of solder around the joint works better for me than feeding it in by hand. Hand feeding always seems to end up with too much solder, or the solder gets hot before the joint.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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Builder01
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Re: Silver soldering set up

Post by Builder01 »

Greg_Lewis wrote: Sun May 17, 2020 11:50 am I find the black flux works better for me than the white stuff. The former seems to have a greater temperature range.
Yes, I have used both black and white flux. The black certainly has longer life for high temperatures. I use it exclusively. It's available on Ebay.
Glenn Brooks
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Re: Silver soldering set up

Post by Glenn Brooks »

On a related note, Builder01 mentioned heating only the copper, which I agree with. However it can Become annealed, and turn soft... i recently solder up some 45* copper pipe fittings to form a 90* angle. The fittings became annealed and very soft. Collapsed when I tried to install.

In these cases, how would one harden up the copper after soldering?

Glenn
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jcbrock
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Re: Silver soldering set up

Post by jcbrock »

When the flux (I too use black) dries out in the container as it will, just add a little water to it and stir it up. I find sneaking up on the melting point and then removing heat as soon as it completely flows helps, overheating is a bad thing. If you do try the cadmium-bearing, I'd do it outside and wear a respirator, that's nasty stuff. I personally won't use it, the safety-sil flows well enough for me. Even that I do in a large space and keep my face well-back.
John Brock
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Builder01
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Re: Silver soldering set up

Post by Builder01 »

Glenn Brooks wrote: Sun May 17, 2020 1:02 pm On a related note, Builder01 mentioned heating only the copper, which I agree with. However it can Become annealed, and turn soft... i recently solder up some 45* copper pipe fittings to form a 90* angle. The fittings became annealed and very soft. Collapsed when I tried to install.

In these cases, how would one harden up the copper after soldering?

Glenn
When doing piping, I make sure the pipe is completely formed before finally silver soldering the cones on. All my bending and forming is done before silver soldering. Attempting to form completely annealed copper tubing can be problematic indeed. All the fittings in the photo are silver soldered without a need to harden up the copper pipe afterward.
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