Welding Copper

I really cannot add much except to say:

My father used to be a machinist. He talked about welding copper with MIG. They would rehab anodes (?) or thinguses like that which were used in their processing vessels. Not sure why they didn't just replace them, but one fellow's job was just to weld up copper anodes. Then they would turn them down and use them again. (Not turn them down as in reject them, but turn them down, as in a lathe.)

I believe it requires a particular wire (copper, of course ....... duh ), and a particular shielding gas.

Please don't quote me on this or flame me if this is wrong. My father has been retired for 13 years.

Steve

Never done it with TIG. The problem with copper is it's high thermal conductivity. You need a LOT of heat. I have seen 3mm copper sheet being gas welded and the nozzle size was huge. Expect to use 3 or 4 times the current as for steel.

John

2 amps per 0.001" of thicknes. Heliume Argon mix gas or even pure helium can help a lot on heavy materiel. The easiest size to weld is 0.045" - 0.087", or 18 ga to 14 ga.

Thinner is a pain to keep from blowing holes through. Heavier and it takes immense amounts of power.

I do it often for light fixtures, vent hoods and such. I use solid copper wire for filler. Electrical wire is fine.

Also helps to preheat with an acetylene torch on thicker pieces.

Richard

Ernie, Thanks once again for the advice. This will be interesting to see how stuff turns out. Guess I need to get another bottle of shielding gas. Michelle

Ernie Leimkuhler wrote:

Wow, I was going to ask the same question today as I'm redoing my kitchen and my wife would love copper countertops. I was planning on using 16 gauge sheet.

Last year I bought an oxyacetylene setup and have been using it to make gym equipment and carts for my woodworking equipment. I've been looking for an excuse to learn tig, but was wondering if it would be better to use GMAW to fabricate the countertop considering I've never used tig (the url below makes it seem like GMAW would work). I considered brazing, but wouldn't that require an overlapping joint for sheet stock?

Now the question: I've got some GMAW experience, but no tig experience. I can rent a Miller Maxstar 140 for $200 a week. Would this machine work for welding 16 gauge copper? Would diligently practicing for a week get my skills up anywhere near to the point where I could weld copper to the point where it wouldn't look unsightly, provided I'm decent with oxyfuel?

Above, you mentioned that 2 amps/.001" are needed. 16 gauge is .0647" so that works out to ~130 amps which seems like just at the limit for the Maxstar 140.

Or would I be better off renting/purchasing a Millermatic 175 and using that with ErCu wire?

Any suggestions would be appreciated.

Thanks in advanced, Aaron

By the way, local shops are charging around $80-100/square foot for installed copper countertops while the raw cost of copper is about $17/foot. So if I do it myself, I can justify the cost of by new welding equipment. As it is, I'm building all the cabinets myself.

I would not try to weld the copper countertops. I would set them up with seams that could be tin soldered. Much easier and much lower distortion. Also don't bother trying to glue down copper. Copper oxides will eventually between the copper and glue and the glue will peal off. Copper oxides have a very weak bond to the base metal. You are better off folding the copper over an edge and using a brass strip to capture the copper. Drill/countersink the brass bar for screws every 6 inches. Use bronze or stainless steel screws.

I have replaced the copper on several bar tops for taverns. Nasty business.

Try to have as much forming of the copper done by a sheet metal shop as possible.

Coper is a pain to work with because it is so easily damaged in the shop.

Don't bother trying to clear coat the copper. You can get away with it for a vent hood, but a countertop has too much wear, the clear coat will eventually peal off.

Thanks for the advice. I think I am going to buy two square feet of 16 gague copper and experiment with soldering and GMAW.

Was thinking about wrapping the copper around the bottom of the substrate. But the brass strip might be nice.

What was nasty about it? Hard to install? Hard to remove?

I'm familiar with clear coats rubbing off. Was just planning on let it age naturally. Although I've seen mention of "oil rubbed" copper. Not exactly sure what type of oil or how long it lasts.

Also, I was reading spec sheets for ErCu MIG wire and they recommend spray transfer for 0.035 wire with settings of 145-185A at 23-25 Volts.

Would lower voltage work? i.e., using a smaller 175A miller that puts out around 20 volts would be in the short circuit mode. Will I get a weld that just looks messy, or will it not be a weld. What I'm basically looking for is a seem that I can sand down and not have it visible.

Picture this...

A copper bar top that has worn through where the servers slide their trays across the bar. For 5 years they just had a plastic cutting board over the hole.

5 years of beer seeping under the copper where it can't be cleaned up. 5 years of beer generating new life forms under the copper.

Now picture the hapless metalworker dumb enough to take the job. Picture his look of abject horror at what he has to deal with under the copper.

shudder!!!!

Oh god it was nasty. Restaurants and bars are just the nastiest places to do metalwork reoair. New bars and restaurants can be fun projects, but repairing old stuff is just gross.

I'm trying to understand what makes this hard. I'm envisioning a wood table with copper on top. Maybe laminated. Cut entire thing out with saw, plasma cutter, slice exothermic torch -- but simply rip out the damaged wood, copper, whatever and rebuild..

The crap under the copper is probably really hates bleach.. This doesn't sound that bad. I was walking down my street and there was a guy with his tanker, pumping out the portable bathroom at a local construction site. I could smell it 100 feet away. Talk about an awful job.

I'm missing something here, aren't I?

__________________ Note: To reply, replace the word 'spam' embedded in return address with 'mail'. N38.6 W121.4

Cutting out the wood was not an option. The copper had to be pealed back in sections because they had installed the beer taps through it, and some idiot had filled the inside of the beer taps with spray foam so they could not be dismantled.

The beer had fermented into a truly disgusting jelly with the smell of really moldy bread.

This all had to be done in one night between 11 pm and 5 am.

Not as gross as cutting out a grease trap in a scrub sink in a bar kitchen so they could add a garbage disposal. food grease residue 1/2" thick is just gross.

I can't really envision doing that in one night between 11PM and 5AM without cutting and swapping the effected area.. Otherwise it sounds pretty close to the "absolute nightmare" But if you managed to do it

-- I'm impressed.

Grease traps are really really gross. Literally need to be in full bio-hazard attire + fresh air delivery system.. Do they offer special "incentive pay" for operations like that?

__________________ Note: To reply, replace the word 'spam' embedded in return address with 'mail'. N38.6 W121.4

You can use a argon regulator for helium, but the gauge will be way way off.

Nobody seems to make a straight Helium flow gauge anymore. Smith makes one for multiple gasses, and that is what I use. According to it helium flows about 3 times as fast as argon.

So a 40 CFH reading on an argon flow tube would be about 120 CFH of helium.