Silver soldering issues

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Bill Crowell

Bill Crowell

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I want to repair some small Mopar parts by silver soldering them back together where they broke. I have no problem melting the silver solder on the work and getting it to flow (using white brazing flux) when using an oxy-acetylene torch with the smallest tip I've got ("00") and the flame adjusted as small as possible, but it's too hot and tends to burn or scorch the work. My buddies told me I should use a butane mini-torch instead. However, the butane mini-torch flame doesn't seem to be hot enough to melt the solder.

Can anybody suggest what I might be doing wrong? Thanks a lot.
 
69_340_GTS said:
What parts/materials are you trying to solder?
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The melted-out pins on a radio vibrator for a '49 Plymouth. They run hot because they're in a low-voltage, high-current circuit, so they were silver soldered originally because lead-based solder will often melt in this application.
 
I left some very small parts with a guy to be silver soldered. He scraped the first one. Then he placed red bricks in a plastic parts tote and filled with water. Wet bricks wicked away the heat. It worked.
 
the acetylene gas has to much carbon try using propane and maybe a higher fluoride flux .
 
I found out that it makes a big difference whether you are using silver-bearing solder, which melts at about 430 degrees, or silver brazing solder, which melts at 600 degrees and above. I need to use the low-melting-point silver-bearing solder. By comparison, ordinary electronic solder melts at about 370 degrees, so the silver-bearing solder gives me an extra 60 degrees. The silver-bearing solder comes with its own flux; not sure if it's different from any other flux.
 
You could try a map gas torch. They get much hotter than a standard propane but not as hot as oxy/acet.

I silver soldered a bung fitting on an antique ford tractor gas tank a couple weeks ago. The silver solder was in stick form like a welding rod and does not have its own flux. I used liquid plumbers (oaty) flux from the hardware store....worked great. I used oxy/acetylene with no problem.
 
They make a little package that has silver solder and liquid flux that melts at 430 degrees. Smith and others make a little torch called a jewelers torch has a lot of different sizes of tips and are great for thin items that can't take the heat.You can get it for Propane or acetylene I have customers that have great success with these. Another way is to use a plumbers setup using Acetylene only
 
Bill Crowell said:
I found out that it makes a big difference whether you are using silver-bearing solder, which melts at about 430 degrees, or silver brazing solder, which melts at 600 degrees and above. I need to use the low-melting-point silver-bearing solder. By comparison, ordinary electronic solder melts at about 370 degrees, so the silver-bearing solder gives me an extra 60 degrees. The silver-bearing solder comes with its own flux; not sure if it's different from any other flux.
Click to expand...

Right. You need something like 95-5 solder. If you're using the thin, hard silver brazing solder, it'll have issues if you can't get it to it's higher required temperature.
 
Bill Crowell said:
I want to repair some small Mopar parts by silver soldering them back together where they broke. I have no problem melting the silver solder on the work and getting it to flow (using white brazing flux) when using an oxy-acetylene torch with the smallest tip I've got ("00") and the flame adjusted as small as possible, but it's too hot and tends to burn or scorch the work. My buddies told me I should use a butane mini-torch instead. However, the butane mini-torch flame doesn't seem to be hot enough to melt the solder.

Can anybody suggest what I might be doing wrong? Thanks a lot.
Click to expand...

You can always take the small parts to a local jewelry repair shop. The silver solder they sell at Home Depot, Lowes and OSH is junk. I had to get the real stuff at a welders supply shop and was not cheap. I use Map gas in my butane torches for the silver solder work.
 
jbc426 said:
You can always take the small parts to a local jewelry repair shop. The silver solder they sell at Home Depot, Lowes and OSH is junk. I had to get the real stuff at a welders supply shop and was not cheap. I use Map gas in my butane torches for the silver solder work.
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Carefeul on using the MAPP in a butane/propane torch. I did and the regulator diaphragm eroded to the point where I had flames coming out from under the regulator knob! This was a hand held model that screwed onto the propane bottle. I chucked it into the backyard corner and quickly hit it with a hose and let it leak out. Anyone have any success with Muggyweld? I bought a few sticks for 8 bucks at a home show. Demo guy was a pro for sure as I could never get it to stick to what I was welding! It always balled up no matter what temp I had the material at.
 
I bought a small mapp gas torch w/bottle for pretty cheap. It has the trigger ignition so its really handy not having to light it by hand.
I think the diffuser may be different for Mapp gas so I wouldnt try using it on a standard propane torch.
 
I think you are on the wrong track here. Vibrators were not originally "silver bearing solder." Let's define this into

"Silver bearing" AKA electrical/ plumbing low temp and

"Silver braze" AKA high temp used to be commonly incorrectly called "silver solder." Used for such purposes as refrigeration tubing

The problem with attempting to use low temp silver bearing solder at all is getting electrical--compatible flux. MOST FLUX (all?) you are going to find in the public / local stores are going to be acidic / plumbing/ hardware use AND NOT FOR USE in electronics

PERSONALLY I would use common lead solder, IE electronics/ radio solder.

I would also check the socket contacts and make sure they are in good shape Heat is generated by poor contacts

On a side note, at my part time job (I'm 69) I am building power wheel chair components and we use "no lead" solder. It is a PITA. It does not flow as well as the old lead based, and is much much fussier to deal with

We do have an additional rosin liquid flux for it which we use for some connections. If you think it will help I will try to get the specs on it. No idea where you'd get small amounts, unless Mouser Electronics, etc
 
I use “kester”solder, and i find it has a higher melting point than most other electronic type solders i have used.
Repaired gm wiper motor boards that failed due to bad solder joints and they last forever.
Oe automotive solder has a lower melting point.
 
boilermaker said:
In refrigeration we use a product called "Stay-Bright" . Its got a lower melting point and flows well.
If you do use silver make sure its 45%. Also, clean the heck out of the surfaces ( sand cloth, wire wheel etc.) Last clean the solder/braze material so it shines before welding. Hope that helps.
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"Stay Bright" and it's flux is an example of something that should NOT be used on electronics/ electrics

Again, he should not be trying to "weld" this. This is a low temp solder application
 
Do you rememeber the X-Box "blue circle of death"? It was when your old x-box LED's formed a lit circle and just flashed. It was due to the first wide scale use of lead free solder balls under the GPU and they would crack and open. You could wrap it in a pillow and turn it on for 20 minutes and it would overheat and reflow the lead free solder!
 
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