Welding Thin Copper

[wh349055]

Hi. I am wanting to get into welding, and I have a question for those who may know. What kind of welder would be used to make a vent like this

[zxcvbob]

It wouldn't be welded. It would be soldered. Or maybe brazed.

Bob

[wh349055]

How do they solder or braze that without ruining the copper?

[Edwin Pawlowski]

Practice, practice, practice. Just the right amount of heat and the right amount of solder and the right touch. It is an art

[ChrisGW]

That is soldered not welded.

ChrisGW

[wh349055]

Would one have to use a flux ? Also, What is the best kind of reasonably priced torch for this work? Thanks

[Bob]

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You would use flux. You might want an iron rather than a torch.

Bob

[Edwin Pawlowski]

Always use flux. No torch, but a big iron. The mass of the iron helps to heat a larger surface.

[PipeDown]

A 100W soldering iron with a very large tip. These are also used to melt lead caning for stained glass windows. You could also probably do it with a lot of other smaller irons but that is a big chunk of copper to get hot in a small area. It may be called a "Hobby soldering iron" as opposed to one for electronic use.

The flux depends somewhat on the solder. Rolls of solder for electrical come with flux inside but lead free solder for plumbing has its own paste flux on the same shelf at the store. In general you can always use resin flux (RMA) but it is alcohol based and harder to clean up. There is also water based fluxes that are easy to clean and will discolor the copper less (not acidic).

Copper is soft enough to bend over the edge of a counter but for really clean creases and sharp angles, you will also need a sheetmetal brake. Much can be done to flatten out mistakes with the right shaped hammers as well (broad flat face and/or a ball peen hammer).

Now if you wanted to make that out of steel you would do best with a spot welder since an arc welder would punch through thin sheet metal. An expert might be able to pull it off with a MIG.

[PipeDown]

One more point. Lead free solder melts at a higher temp but since you will not be drinking water off a vent, it should be OK to use lead/tin solder

[Rich]

It's also been scotch brited as you can see in the side view at the bottom where the pivot comes through the scotch brite couldn't get to the area above and below the pivot revealing that work was done to clean this up after soldering. Were I work they have a brite dip that they use to remove the flux residue and any oxidation that took place during the heating then the brite dip is rinsed off with water.

Rich

[mm]

How would you weld it without ruining the copper?

The irons for this are quite big. Nothing they sell at Radio Shack or electronics stores.

Remove NOPSAM to email me. Please let me know if you have posted also.

[Chris Lewis]

According to PipeDown :

Uh, no. A soldering iron isn't hot enough to melt lead. You use ordinary solder to join lead just as you do with copper.

These irons are usually for stained glass work. There are plumber's irons, usually around 300W. Which you'll need will depend on the copper sheet thickness and piece size.

There are also "soldering iron" attachments for standard propane torches. If you buy a propane torch kit, it'll probably include one.

If you use a soldering iron (or a soldering iron attachment on a torch), discoloring the copper sheet will be pretty minimal.

[Joshua Putnam]

If I were doing that, if I wanted a good color match on the joints I'd probably use self-fluxing copper brazing rod and a small acetylene torch for good heat control. If the color match on the joints wasn't important, plain old 60/40 solder and acid flux.

If you're doing thin copper with an oxy-acetylene torch you need to be careful not to overheat it, but it's a lot faster than doing it with an electric iron.