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Advice on Brass wire soldering Answered

Hi all :)

I'm totally new to soldering and want to make a project involving soldering two pieces of 12 gauge brass wire using 20 gauge brass solder.

My issue is the solder won't flow and the brass just darkens after a while of holding the torch to the metal.

Here's the equipment I'm currently using:

Solder: https://www.etsy.com/listing/291425439/brass-wire-...

  • Silver - 38% Copper - 32% Zinc - 28% Tin - 2% Melt Point - 1200º F (650º C) Flow Point - 1330º F (721º C)

Wire: https://www.etsy.com/listing/551472422/1-lb-round-...

  • Solid Round Yellow Brass Wire. Metal : # 260 Yellow Brass. Melting point according to seller: 1650 to 1720º F

Torch: Micro torch Roburn MT 770P

Fuel: Bernzomatic Butane

Flux: Oatey No.95

Application:

  1. I clean and sand (using sandpaper and/or a file) the brass wire, and the solder.
  2. Apply flux liberally
  3. Apply heat using just in front of the inner cone (flame is totally blue with a slight hiss), starting on the sides of the wire and working my way to the joint.

The metal glows but doesn't stay very much.

Do I need a propane torch? What am I doing wrong?

Thanks so much!

Discussions

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rickharris

9 days ago

Technically your trying to braze.

The flux is to clean the metal and prevent oxidation

i generally use Borax as a flux, it's good and cheap for brazing and silver soldering.

This is how I would do it.
1. Clean both wires
2. Make sure they are in close contact and heat then dip in flux.
3. Heat brazing rod and dip in flux to coat.
4. Heat joint to red hot applying the brazing rod - when temp is right it will soften and flow into the joint.
5. allow to cool. brush off excess flux.

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Tooltiprickharris

Reply 9 days ago

Thanks for the reply! What type of fuel would you suggest I use to heat the brass?

Lots to think about here...

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rickharrisTooltip

Reply 4 days ago

Anything that can get it red hot. propane is fine for small items, Oxy acetylene for bigger things. Gas and forced air is also a good option if you don't have access to oxy acetylene.

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Jack A Lopez

10 days ago

This seems like an unusual choice of solder to me, just because its melting point is so high, i.e. 650 C.

Most solders have a melting point less than 300 C.

Probably the first solder I ever used was (Sn60,Pb40), for soldering electrical components to a circuit board. That stuff has melting point near about 190 C, and can be melted with a soldering iron.

Probably the second solder I ever used was (Sn95,Sb5) for soldering copper pipe fittings and copper plumbing pipe. That stuff has melting point near 240 C, and usually is melted with a propane, or MAPP gas, torch.

Flux, of some kind, is needed to keep the pieces of metal from oxidizing while in the process of being heated, and also to help the solder wet them, and flow onto them, and bond with them.

For electrical solder, the flux is often this stuff called, "rosin", and it is cleverly included with the solder, in a so-called, "rosin core", basically the solder is a hollow tube, with rosin flux inside. I can only speculate as to what kind of magic baked it in there in first place.

For plumbing solder the flux is applied separately, with a brush, to fittings and pipe ends that have been cleaned with a wire brush, or steel wool, or both, to remove a layer of oxides and dirt, and basically make them shiny and pretty, prior to being painted with flux and soldered.

I have done some, what they call "brazing" too, but I never mastered the art.

As far as I can tell, the most significant difference between "soldering" and "brazing" is the melting point of the filler metal.

Essentially, "brazing" is a word for high temperature soldering.

To me it always seemed like it was the high temperature needed for brazing that made it more challenging.

First the joint had to be set up in a place where it could get hot, like suspended in space, and surrounded by air, or insulating bricks.

Then it had to be heated with a flame. My past attempts used propane or MAPP gas, for this, and it took a loooooooooooong time, before the work pieces hot enough to melt the brazing alloy.

Then the work with the brazing alloy had to be done quickly, because naturally the work pieces wanted to cool back down again.

Did I mention cheap, low temperature solders, like (Sn60,Pb40) or (Sn95,Sb5) will stick to brass? Because they totally will.

But perhaps you have some good reason for using the high-melting alloy you are using. Like maybe you need it to be super strong or something.

Final thing: I was going to link to the Wikipedia pages for, "List of solder alloys" and "List of brazing alloys", so that you do not have to take my word for it, regarding this general trend in difference in melting point temperatures between the two.

https://en.wikipedia.org/wiki/Solder_alloys

https://en.wikipedia.org/wiki/List_of_brazing_allo...

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TooltipJack A Lopez

Reply 8 days ago

Hey mate,

Thanks for the detailed reply! You're absolutely right that what they called "solder" is not solder because of the high melting point. As it turns out, this is indeed brazing (as mentioned here as well). After some advice here and over at /r/plumbing I've come to think that:

A) my butane torch won't give enough BTUs for this application. I've since ordered a TS8000 and MAPP Pro gas.

B) my flux was totally inadequate for the temps I need and was burning, leaving a black coat on everything. I got some brazing flux (Harris SSWF1 Stay Silv Brazing Flux).

In terms of why I'm using the brazing wire and not silver solder or 60/40 solder, it's because this is an artistic piece and it's important that I color match the pieces. Using that solder leaves a silver bit on it which just won't do. I'd rather struggle a bit now, get better at brazing, and then be able to make something that looks really nice (or at least pretty nice)

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Downunder35m

10 days ago

Two problems, proper heat and preventing oxidation.
The cleaning of the brass is a must do to clean it.
The flux should be suited for the job!
Acid based flux that forms a crust is better here than resin based ones as the later won't tolerate the heat for long.
What you call soldering is actually brazing ;)

Try this old beginner's trick:
Have a fine stainless steel brush at hand.
Heat the wire and use the brush to clean the wire when hot.
With some flux on the brush you adda thin coating of flux at the same time.
Quickly add the solder by rubbing it over the surface of the wire - you want to melt the solder on the metal but not with the flame.
As an added exercise you can try to find the sweet spot of your flame just with the solder.
The point where it starts to melt is what you need, much higher temp will only cause problems.
And if the flame is really hot then it can be beneficial to not use it directly on the metal - this drastically reduces the reduction of the flux.

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TooltipDownunder35m

Reply 10 days ago

Hey, thanks for the detailed reply!

I'll pick up some acid based flux and a fine SS brush and give it a shot.

Do you think the butane torch produces sufficient heat for the task or should I up my game to a propane torch?

Also, I've been thinking more about trying to just use standard plumbing solder for the job. I have a feeling it will be easier all around, and the project is purely ornamental. The downside is the color won't match. I may be able to get around that by hiding the solder on the "back" side of the seam... I'm torn but it might be worth just trying and see how it looks.

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Downunder35mTooltip

Reply 10 days ago

If you get it glowing red hot than the torch will be fine.
Normal solder is definately easier but as you said, the color is a problem.