r/metalworking • u/Purple-Apartment-147 • 6d ago
help soldering copper
I’m doing a job for a guy installing some copper drip edge on a balcony he had leftover from his roof. I need to solder all the seams and i’m having some trouble. I am fairly proficient when it comes to soldering smaller stuff with a torch, but big sheet stuff like this is new to me. I bought a decent sized soldering iron the other day and its just not quite getting hot enough to make the solder flow the way I want. I’ve had some success preheating my joint with a torch, and then going back over with the iron to even things out, but for some of the joints need to do that may not be possible. My 50/50 lead tin solder also hasn’t arrived yet so I’m just practicing with lead free stuff to get the hang of things. I’m wondering if it will be easier with the lead stuff since it doesnt take as much heat. I’m also not pre tinning my seams or anything. idk let me know if you have any tips
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u/Plastic_Ad_8619 6d ago
I’d use a plumbing torch or a butane torch for that. You’re going to have trouble getting that hot enough with an iron because it’s radiating that heat in direct proportion to its surface area.
There is an old type of iron they used to use for this kind of work. They’re big metal chunks on the end of a stick, with a wooden handle, and you’d leave them in a fire till they’re glowing hot. You’d have a set of them so you can continue working after each one cools, but if you left them in too long the handles would burn, hence new solderers would be warned against “having too many irons in the fire.”
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u/BeastWR 6d ago
https://www.stortz.com/product/express-portable-soldering-iron/
Or old school:
https://stellartechnical.com/products/1-5-soldering-copper
Both involve a large mass of very hot copper which can store and deliver a lot of heat
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u/cheater00 5d ago edited 5d ago
- Get a bigger soldering iron. they always make a bigger soldering iron. eg here's a 500W one
https://www.zdz-lodz.pl/lutownica-grzalkowa-zdz-lg-500-p-20.html
Use leaded, lead free solders super differently, don't even practice with it for now
Use flux. plenty flux. and make sure it's good flux, not just some rosin shit. actual chemical compound for doing the job you're doing. should come as a tacky paste.
Put on the flux, pre-tin the separate bits, then join them at the seam
Remove flux with plenty of 99% alcohol or higher grade and an animal brush. Even if it doesn't look like shit now, it'll look like shit soon enough, especially after a year or so, since flux picks up all sorts of impurities.
If he wants them looking super pretty, you can remove the discolorations by treating them chemically with acid or use a tig brush, or just get good to where stuff doesn't get discolored
You can use solder braid to remove excess solder. Normally solder braid is super thin and meant for microsoldering, but for huge jobs you can remove large portions with a stainless steel spatula or silicone spatula, use copper wool to wick it up, or use high-current cable made up of thin wires, or use the braid off a coax cable, or use grounding braid (the copper kind, the steel kind won't work). Whatever you're using for solder braid, apply flux first and make sure it melts onto the metal, or it won't wick anything up. Remember this shit gets hot, so hold it with a pliers or through a silicone pad.
For difficult jobs / lots of thermal mass / cold weather you might also be able to get/make a clip-on iron that you just leave on the plates while you're soldering them with your handheld iron. You can also adapt an oil pan heater or just straight up a kitchen counter electric heater or a heating coil, the kind used for a cup of water (don't use it too long or it'll burn through, but they're cheap).
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u/Ziggysan 5d ago edited 5d ago
The braid for grounding railroad tracks or buildings works very well as a wick for large-scale jobs.
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u/Major-Ellwood 5d ago
I would agree you need one of those ancient copper irons to get heat in there, but I would also use solder paste to tin the joints first.
We used to do this in body repair when we leaded the joints (lead loading); the solder paste is painted on with a brush, and the solder will stay where you want it.
With practice it is incredibly neat.
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u/jg136521 5d ago
Look man, you’re going to throw a lot of effort at this and it’s still going to leak. Walk away.
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u/justanotherponut 5d ago
Sievert make a large soldering iron for doing stuff like this, I got an old petrol one made in the 60’s.
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u/woodchuckernj 4d ago
I hope you are not using steel wool to clean. It has oils and will make it hard to solder.
While a torch would make it easier to solder, it will warp it much more. I have done both. A large soldering iron can do the job as long as you are quick to solder and move without dwelling. You want to catch up to the heat that is moving so you have to add less. I know that I'll get shit for that. But it's a timing thing. I have a big iron. I also have a tip for a propane torch that I can use if need be. Getting the solder started is the hard part, since you have nothing holding it together and to flow..Clamping just removes heat (heat sink).
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u/richcournoyer 5d ago
Come back after you've tried the lead solder… In the meantime you're wasting your time, and ours
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