tig welding copper

cruzan · Post by **cruzan** » Sun Aug 27, 2006 8:45 pm

has anyone had any luck tig welding copper? ive read up on it on a few metal working sites and they say it works. so i might give it a try jsut for the hell of it

Post by **golden pond** » Mon Aug 28, 2006 1:28 am

Yes I've done quite a bit of it through the years on cross over tubing on air compressers and other things, I used silver brazing rods. Worked well for me.

markx · Post by **markx** » Mon Aug 28, 2006 1:49 am

Copper brazing with a TIG machine works well, but welding copper with copper is quite tricky since the heat conductivity tends to ruin the process. I've done quite a bit of copper brazing with a tig myself. All the joints on my first reflux still were brazed including the aftercooler and the cooling jacket in the column head.

Post by **Uncle Jesse** » Mon Aug 28, 2006 8:38 am

make sure you use argon on both sides of the weld so that you don't get any pitting. it's not easy to TIG weld copper, takes practice.

oldpete · Post by **oldpete** » Tue Aug 29, 2006 5:16 am

ive been doing some tig welding of copper for my project, pain in the butt, the parts soak up so much heat everything gets oxidized and goes from molten puddle to giant hole in the work piece quickly. not to mention awful heat distortion.

markx · Post by **markx** » Tue Aug 29, 2006 5:39 am

Use a brazing rod that melts on lower temperatures than copper. That way you don't have to play so close to the melting temp of copper and manage to avoid the heat distortion.

Uncle Remus · Post by **Uncle Remus** » Tue Aug 29, 2006 6:39 am

Why make things more difficult than they have to be? Why not just solder?

Rotgut · Post by **Rotgut** » Tue Aug 29, 2006 4:57 pm

is there something to look for in the tig welding rods? i want to weld a salad bowl to my keg but was worried if it would be safe to use

markx · Post by **markx** » Tue Aug 29, 2006 11:53 pm

Use the appropriate SS filler for your materials. 315 e.g. or whatever type of stainless your keg is made of.

Post by **golden pond** » Wed Aug 30, 2006 4:08 pm

I'd use 304 SS tig rods. 1/16 diameter or less.

agl · Post by **agl** » Sat Sep 02, 2006 5:51 pm

I have tigged a few stills together with many copper-copper and copper-stainless welds. The thermal conductivity does pose a challenge, similar but more extreme than with aluminum. The thing to keep in mind when welding is that the part has to preheat a bit before you can get a good puddle and penetration - which is were it gets tricky preventing blow through. Try to hold a small puddle for a few seconds before beginning the weld. and it will become obviously easier to continue the weld once the part is heated.
use DC - same polarity as with steel, and I have found argon sheild gas to be quite effective.
I used solid copper electrical wire for filler rod. The end result is worth the effort, it looks beautiful and there are no unknown metals and fluxes to worry about.

cruzan · Post by **cruzan** » Mon Sep 04, 2006 9:09 pm

copper to stainless? wow how did you go about this? did you keep the arc mainly on the stainless? what kind of filler did you use if any?

Post by **azeo** » Fri Sep 08, 2006 1:41 pm

I found tig welding copper tricky, I'm not an experienced welder, but did gain lots of practice on SS, a different kettle of fish than copper!

I found that getting parts hot enough to weld easily on a constant current meant lot's of of oxidation and pitting, I didn't have a way of bathing the whole part in argon and it tends to glow dull red all over before getting a good pool- close then to melting through and softening!

What did work, and got a nice result in the end, was to set up the welder for a high current, bang the pedal hard to get to get the weld pool going straight away before the heat could run away, running a series of tacks with a wet rag handy for cooling as necessary, then joining those tacks up and cleaning up any blow holes with more passes.

Not always always a super pretty job, but functional and strong, and allows brazing or soldering nearby on the part without other bits falling off!

It's pretty quick work and the right sized filler rod helps. There's a fair bit of art in manipulating the torch and filler angles and movements, the right amount of electrode stick out helps (with a pointed grind as for stainless), even the way one holds the darn thing and comfort over the table helps..

If one can arrange the parts so "sacrificial" melting can be used instead of a filler, that's one less thing to worry about! I too used electrical wire, stripping various sizes of "conduit wire" to get a variety of gauges. Haven't yet found out if electrical wire has any alloyed additives - hoping that it doesn't!

I also tried using the auto "pulsed" function on the welder, but was a bit inexperienced to really use it successfully, I'm sure it could work well on copper though as manual control is doing something similar..

Sorry, another long post! but hope it helps, cheers

decoy · Post by **decoy** » Sat Sep 09, 2006 9:49 pm

There apears to be some confusion between tiging and brasing,

Tiging involves pudeling 2 metals with addition of a filler rod genraly of the same material shielded by an inert gas or mixture of such as Argon, Carbon dioxide, Helium etc to prevent oxidisation.

Brasing or soldering is when you join 2 metals with a heat souces that dose not bring the metals to a melting point but is able to bring a third material commonly Lead or lead free solder, brasing or silver solder filler rod to a melting point or temperature at which the filler rod will bond with the job.

welding copper to copper or stainless to stainless and eaven copper to stainles is relativly easy if the materials are of similar thickness.
Copper discipates or conducts heat very quickly so you will need a higher current to tig weld copper compare to simmilar size job in stainless.

a tip when useing a tig to weld tube or a drum is to fill it with the same gas you are useing for shielding, this can be achived by covering any openings with masking tape or blank end plates etc then punch a small hole in the masking tape and pushing a small hose from the shield gas regulator then just let gas run into when its compleatly purged of air and replaced with your shield gas, pull out the hose and stick a bit of tape over the hole.

But when do you know you have enough gas in there???
1, buy a gas meter.
2. if the job is small just guessand give it a bit more.
3. in the case of tube, stick the tig gun in the center end of the tube poking the tungsten tip through the masking tape and it will start to ark or spark to the tube wall as the concentration of argon etc gets high enough.

this will prevent piting and oxidisation inside the tube and with a bit of practice it will result in a smooth finish inside the tube as if it was welded from the inside, otherwise known as a food graid weld.

cheers