welding brass?

Hi
I might have to do that: Weld some (hopefully many) brass cases for RF shielding. Now I could do that with OA or a TIG. I would have to lend that TIG (DC
only).
But I have never welded brass before. Neither with OA nor TIG. Is that difficult (not a welding newbie at all). Can I simply use some brass rod? Or will the Pb in it (most have) make problems?
The case will be 200 * 100 * 80 mm and 5mm thick. I fear it is more a heat sink than a piece of cake. How much amps would be enough for TIGing (if that is the way to go)?
Yes, I will make the prototype it with silver soldering, but I guess it won't be much fun (regarding the size and the pieces fixing and falling apart. All that with tight tolerances).
Nick
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On Wed, 14 Dec 2005 12:28:14 +0100, snipped-for-privacy@gmx.de (Nick Mller) wrote:

I can't think why anyone would want to. Brass doesn't like being worked hot - it's mechanically fragile when hot and the melting point is too low for comfort, relative to any likely filler rod. Because it has good conductivity you have to pump plenty of heat in, but get that temperature just a little too high and you've made a blowhole.
I'd silver solder them instead.
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I tried OA with some scrap. And scrap came out! :-) I have welded Al with OA. But Al is easy compared to brass.
I'll stay with silver solder, (not soft soldering) because it has to withstand quite some mechanical load, it is to big and doesn't have enough overlaps. Yes, I milled the sides to have a Z-shaped overlap.
Nick
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If it's only for RF shielding, soft solder would be the way to go. If you can make them with good sized overlaps on the joints they will be reasonably strong.
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A product called Solder-It now goes into my toolbox and workbench. Paste hypodermic dispenser, great flux, probably about 6 percent Silver, very, very strong, easy to use.
MUCH stronger than the wimpy 2 or 3 percent stuff we used to get at Rat Shack. Seen in many hardware stores... / just my 1.7 cents worth / mark
jtaylor wrote:

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I once used one like this. It was the giggest PITA I ever had. Must have been a different brand.
I'll shop for that.
I just silver soldered the case. And it was the pain expected. This is something that cries for a jig and a fan-burner (many little flames, not just one big).
Nick
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I've tried TIG on brass with limited success and went to soft soldering. Than main issue was not Pb but Zn. When the brass gets hot enough to melt you tend to get zinc burning out producing white zinc oxide which is not good. Probably a better place to ask this question is on sci.engr.joining.welding. It may be possible to TIG it with an appropriate rod that melts lower than the brass so you are brazing it rather than welding. I think this question has come up before and Ernie has responded with useful info.
Nick Mller wrote:

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I tried tigging brass several years ago with a brazing rod that I'd sanded all the flux off of. It didn't work as the zinc cooked out of the rod making a mess as Mr. Billington noted above. I went to the National Welders local shop, told them what I was trying to do, and they sold me the correct rods. Worked just fine after that, but you've really got to turn up the amps as the brass was very good at conducting the heat away.
Garrett Fulton
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Now was this welding or brazing? Did the brass melt (and not just the rod). I ask, because I found some brass welding rods that are also for brazing steel.
Yes, the zinc is the problem. I just tried it with OA and both a reducing and oxidizing flame. But, well, I won't try it again with a stock brass rod. :-)
Nick
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Have you ever tried Laser welding? I weld brass all the time with great success. I have to say that most of what I weld is less than 5mm but, I'm sure that it can be done. I use regular brass wire for the filler and it's very strong when done right.
Neill
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wrote:

No, these were rods for welding brass. I was trying to weld up an adapter fitting so I could put braided steel fuel lines on my old '56 Panhead. The rods the welding supply gave me just melted straightaway along with the brass fitting with no more of the smoky zinc mess and contamination. I ruined the first fitting as it was similar to aluminum in that it was hard to tell at first when you were putting too much heat to it and it caved in on me. Just took a little practice, but I finally made a nice weld of it. Sorry, Nick, but I don't remember the specs on the rods. If you want, I'll stop at the welding supply place next week and ask those guys.
Garrett Fulton
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Sorry that I asked, but some people can't distinguish between welding and brazing. You are _NOT_ one of them. :-)

That sounds very good!

I saw that with my quick-hack-test. :-)

Thank you for the very kind offer, but I fear I won't get that brand here in Kraut-land. But I'll stop by at my welding shop and ask for it. Now I know it exists and I know I can get acceptable results.
Nick
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Wonder if a gas box would help - Argon maybe - Not only is the zinc vaporizing, but oxidizing also ? Might never beat it. Unless under a heavy layer of flux.
I was able to braze a bronze pipe to a 1/4" copper sheet the size of note book paper. That took a lot of heat.
I then did the same thing to a sheet of 16ga steel - and brazed a line - within heavy flux - then added the bronze pipe - and when the bronze rod attached to the pipe - it flowed into the puddle already on the steel. In a sense - I tinned the steel with a layer of bronze before trying to put the pipe on.
'tinning' is done in Tin-Lead soldering all of the time. It is useful in other metal applications as well.
Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder
Nick Mller wrote:

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David Billington wrote:

I've torch-brazed a few HEAVY brass pieces and had good success with it. This was a tank with a 1/4" brass bottom and .062 walls. I didn't have my TIG at the time, but will have to try it the next time such a job comes up. I have some low-temp brazing rod that melts at a low enough temp that melting the brass is not a problem.
Jon
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For tight tolerances and production, I suspect the best way would be using furnace silver-brazing with a jig to keep things square and together. Usually a paste flux with ground braze filler or silver-braze filler preforms are used. There are books out there on the subject. If you could find someone that has a pottery kiln, you could probably prototype things using that. Or use soft solder if you don't need the strength. It's available as a paste in flux as well. You might be able to use a kitchen oven for that, depending on what solder alloy you get.
Stan
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Yes, I have to agree with the experiences I had today. A jig is a must. But for the furnace, I have to step back. Would like to have, can't afford.
Nick
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On 14 Dec 2005 14:16:03 -0800, snipped-for-privacy@prolynx.com wrote:

Don't braze in a pottery kiln. You'll destroy the refractory lining and you'll annoy the potter. Flux spills eat right through it and fumes aren't much better.
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Nick Mller wrote:

Try a carbon arc with a filler rod.
John
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Not sure of your exact application, try jigging with castable refractory. Jewelers do it all the time. The soldering heat for hard or soft solder can be a transformer soldering machine. Google on American Beauty, one brand name. Can be homebuilt.

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Not sure of your exact application, try jigging with castable refractory. Jewelers do it all the time. The soldering heat for hard or soft solder can be a transformer soldering machine. Google on American Beauty, one brand name. Can be homebuilt.

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