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Brazing with Butane Torch???

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  • Brazing with Butane Torch???

    I'm looking for one of those small Butane torches to use for small heating jobs and noticed that some of the torches claim that they can braze. They also claim a temperature of 1300 degrees.
    Is it possible for a Butaine torch to reach that temperature? Can they really melt a brazing rod and get the object metals hot enough to accept the brazing material?
    Much thanks for all help.

  • #2
    Temperature claims are meaningless. Even a candle flame gets hotter than that. Unless you only want to braze the thinnest of material you won't have much luck with propane. I have one of those turbo-whatever propane torches and it is unreliable at best. It tends to swallow the flame or go out easily. No fun at all.
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    • #3
      That must be 1300 C? 2372 F?

      I can believe it gets that hot, but I think the operative word in your message is "small." You could probably use a butane torch to braze a couple of 1/8" dia. rods together, using a 1/16" brazing rod. Anything much larger, I suspect it wouldn't have the oomph to get the mass of the material hot enough. Brazing requires 1800F or so, if memory serves.

      You could probably do better with silver solder, as that's down around 1200F, and it is very strong as well, but even with that you're talking "small."

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      • #4
        Yes, propane wont do very 'heat sinking'/large items, but IF you are brazing either thin sheet or small rod >3/8 together, then it might. As long as it gets somewhat above the dull red point, the following rod will melt and flow.

        An aside, I sometimes do things with bicycles and that is thin mostly. I can easily braze 1/4 bolts and nuts to items IF the item can get hot enough also. My torch is the standard propane/mapp and some items require

        I use a rod from gasflux called C-04. It is very fluid, but not uncontrollablely so. The temp at which it flows is on the 'low' side temperature wise (cannot remember what but around 1400F or so melting point which puts it above silver braze and below most other rods). Makes nice smooth fillets for me (just learning, not a welder/brazer by profession).

        The following supplier is where I got the flux and rod from...just FYI.

        Henry James is a small supplier on the west coast.

        Just my $.02 worth.

        His webpage takes some doing, scroll down to bottom and pick orderform then click on the subject that has braze in it. He is a bike builder/suppler of parts/equipment.

        I did some research as confusion seems to rain as to temps. The following is a copy and paste from: razing%20is%20all%20about/Part%203.htm

        Advantages of a brazed joint.

        First, a brazed joint is a strong joint. A properly-made brazed joint (like a welded joint) will in many cases be as strong or stronger than the metals being joined. Second, the joint is made at relatively low temperatures. Brazing temperatures generally range from about 1150آ°F to 1600آ°F (620آ°C to 870آ°'C). Most significant, the base metals are never melted. Since the base metals are not melted, the can typically retain most of their physical properties. And this "integrity" of the base metals is characteristic of all brazed joints, of thin-section as well as thick-section joints. Also, the lower heat minimizes any danger of metal distortion or warping. (Consider too, that lower temperatures need less heat which can be a significant cost-saving factor.) And important advantage of brazing is the ease with which it joins dissimilar metals. If you don't have to melt the base metals to join them, it doesn't matter if they have widely different melting points. You can braze steel to copper as easily as steel to steel. Welding is a different story. You must melt the vase metals to fuse them. So if you try to weld copper (melting point 1981آ°'F/1083آ°C) to steel (melting point 2500آ°F/1370آ°C), you have to employ rather sophisticated, and expensive, welding techniques. The total ease of joining dissimilar metals through conventional brazing procedures means you can select whatever metals are best suited to the function of the assembly--knowing you'll have no problem joining them no matter how widely they vary in melting temperatures. Another advantage of a brazed joint is its good appearance. The comparison between the tiny, neat fillet of a brazed joint and the thick, irregular bead of a welded joint is like night and day.

        Post script: I live in an apartment and all I can 'get away with' is a small propane/mapp torch. I am sure the landlord would evict if I had anything bigger. Also, cannot afford more stuff money/space wise.

        [This message has been edited by Crazy Ed (edited 07-05-2005).]

        [This message has been edited by Crazy Ed (edited 07-05-2005).]

        [This message has been edited by Crazy Ed (edited 07-05-2005).]


        • #5
          Ed-(and all)

          Thanks for the info on the C-04 brazing rod. I'll look into it. I've talked to some other people who have the butane torches and they say that at the hottest, these torches will not heat a 1/8 steel rod to the temperature needed for brazing.
          Looks like I'll have to go to oxy/acet to do true brazing.



          • #6
            Steve, I have one of those little Oxy-Mapp torches and I am really restricted in size to what I can Silver Solder with it. It is O.K. for heat treating SMALL Steel parts, but not those with very much mass. In fact, I could not get enough heat out of it to Silver Solder a 1/4" nipple in the bottom of a 3-1/2" dia. Copper boiler using Easy-Flow. Another problem is that the little Oxygen bottles, which are good for only about a 7 minute burn, are now scarcer to find than hens' teeth. Wal-Mart used to stock them but no longer do so around here. I am thinking that whenever I am able to up-grade, I will get one of those little Oxy-Acetylene "Tote Torches" that can be very easily stashed in a closet.


            • #7
              I have one of the butane torches I think you talking about. If it's the one I am thinking of it is refillable with the butane you get for a lighter. It works for small items only. Like if you want to straighten out and allen wrench(1/4 or less) so you could chuck in a drill. The solder attachment that came with it works pretty good for larger electronic components. Believe it or not you can get one at Bed Bath and Beyond. They sell them for caramelizing Creme Brule'

              I also have the small oxy/propane/mapp gas torched too. Like is mentioned they are good for welding or brazing small steel items. Used it to weld an exhaust bracket Good for those types of repairs on the trail since it can secured in a small space.

              The 7 minute burn time for an disposable oxygen bottle goes faster than you think. It can get expensive too. the last time I bought one of them it was around $8. The torch kit was like forty bucks.

              IMHO Save your money and get a good torch set, regulators and refillable tanks if your going to be doing anything substantial.

              Remember you can always get a small tip to do delicate work with a bigger torch, but a small torch can never be a big torch.


              • #8
                I think the problem you guys are having silver solder with propane/butane (about the same temp, right?) is btu's not temp. - its the size of torch you are using, not the fuel. I have a larger propane torch on a 20 lb cylinder and it gets used 10x as much as the oxy/acet set, for silver solder and heat treating - large and small.

                Propane is actually better for silver soldering as o/a can easily get things too hot.

                The other thing that will help is to put the work on refractory brick with another behind and beside, sort of forming a little nook with heat being reflected back on three sides
                located in Toronto Ontario


                • #9

                  Thanks for the into.
                  Agree 100%. I tried a small butane torch this weekend and found it to be useless.
                  I have a MAPP gas unit also and run through the Oxygen tanks in a few minutes (and that's on a small project.) I can get the tanks and Home Depot or Lowe's (here in northern VA.) but its still a bother having to replace them constantly. I'm looking into the small tote O/A system also.



                  • #10
                    McGyver is right on the mark.

                    I can silver solder, soft solder, or braze using sil-flo with either propane or butane. It is a matter of matching the torch to the work.

                    Woth O/A, its so hot that you actually use the heatsinking to avoid cooking and melting the work.....sometimes, unless you were trying to.

                    WHere O/A excels is in actual temperature, AND in applying high heat to a local area rapidly. Try re-soldering a car radiator with propane someday..... you'll be going to a radiator shop with it afterwards, and they will use a hotter torch than propane.....

                    [This message has been edited by J Tiers (edited 07-11-2005).]
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