Soldering to Large Metal Objects


Introduction: Soldering to Large Metal Objects

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Large metal objects inhibit your ability to solder because they draw all of the heat away from the point of...well... soldering? Normally you would either have to leave your soldering iron on the piece of metal long enough to heat the entire thing up to about 800 degrees Fahrenheit (which can take a LONG time), or you would settle for a weak joint and end up hot-gluing or epoxying over it in order to make sure that it won't come off.

However, by following these few simple steps, you can create a strong solder joint and not have to worry about the joint breaking.


Propane torch
Soldering iron (preferable)

Step 1: Prep / Getting Solder Onto the Metal

Clamp the metal so that the flame from the propane torch will not melt/burn anything you have lying around

Light the torch and make the flame really low (see picture).

Hold the torch up to the metal and heat it up.
Be sure to move the torch back and forth so that you don't melt the metal itself.
Every once in a while remove the flame and test to see if you can melt solder on the hot metal.
Once the solder begins to melt, heat the metal up for a few more seconds and then remove the flame for good (you can turn off the torch now).
Quickly apply solder to the hot metal, try to cover the entire area you are going to use.
Don't be afraid to use excess solder, solder is your friend =).

You want the solder to look shiny when it cools. If it doesn't look shiny then quickly heat it up with the torch and let it cool without touching it.

Step 2: Solder the Object to the Large Piece of Metal

Prepare your object for soldering, commander.

Tin the leads / wire you are going to solder onto the wire.
Once again, don't be afraid to use a lot of solder; Solder IS your only friend that enjoys getting poked with a soldering iron.

Once tinned, tin the tip on your soldering iron, leave a good glob of solder on the tip.

Swipe your iron tip, glob facing down, over the solder patch on the piece of metal.
You want to get some solder onto the solder on the metal, and make sure that when you finish the solder that you just put on is shiny. If it isn't shiny, torch it until it is and try again.

Now, hold the lead / wire over the new, shiny patch of solder and again swipe your soldering iron over the lead / wire, pushing down slightly. The solder that you recently put onto the patch should melt and merge with the solder on the lead / wire.




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    Trying to solder 1/16" round tig wire into a drilled hole in 1" sold round steel bar. By the time I heat the bar up the paste has oxidized and so has the surfaces of both wire and bar. Is there a way to do this with solder. I have been using silver solder and proper paste, even tried plumbing solder with the proper paste. I usually use mapp gas and a torch. hate to use epoxy.


    How big is that wire? 12gauge, 14gauge?

    so.. you solder. which is a pretty unremarkable use for a soldering iron but if you need to do heavier soldering you can get unpowered irons with really big copper tips. you heat them in a small furnace and use the flat side to join tinned hunks of metal

    1 reply

    lol. that made me laugh. "...pretty unremarkable use for a..." i couldnt have said it better myself.


    Okay, but what about soldering pieces of galvanized wire together? What type of solder can you use? The ending result is jewellery, so it's quite fine pieces I want to join. I have a lightweight blowtorch and a roll of solid, lead-free solder, but it's not cored... can I get away with NOT using flux?

    1 reply

    Heh - flux is the superhero of the soldering world - it lets you do everything.

    I'd use silver-bearing solder and tons of (external) flux. I've never tried soldering galvanized wire - it will most definitely interfere with the process though. You might want to try and scrape off the coating where you're going to make your joints.

    Good luck!

    Do you need flux to solder? I have acid core solder.

    You can't weld with a 25W soldering iron. If you were trying to weld with a soldering iron, I'd have to guess the iron would melt first... Unless you modded it with 2 electrodes, in which case it might work, but only for very thin metals.

    i prefer to solder using the torch on its own, but well thought out BTW, you can get little pencil flame torches with soldering iron tips

    1 reply

    Yesssss, I need to get some of those. Thanks for your approval. =)

    you can also buy a solder gun (would be cheaper than a propane torch). I've used solder guns to solder really big pieces of metal (really thick cable, maybe six times as thick and a lot longer than the metal shown in the pictures) effectively.

    3 replies

    Oh, wow. I wasn't aware of the power of said solder guns. Yeah, that would be a great alternative. Unfortunately, I don't have one, but I do have a propane torch lying around. I guess if you had a solder gun that would be the best method.

    the thick cable I mentioned was not solid cable, it was stranded, I think that makes it easier to solder (higher surface area to accept heat).

    Yes, that would certainly make it easier to solder. My method is a lot like sweating pipes in plumbing. However, rather than joining pipes, you are joining a small wire or component to a large piece of metal.

    There is to be had a contact soldering tip (like the one on your electric iron, only bigger) that you fit to the end of the propane torch. The flame heats the tip, tip heats the joint.