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  • Brazing Gurus help me out here

    Hi
    I am perplexed about a silversoldering issue I have encountered.
    I was making a fuel tank from 4" dia. copper tube 1/8th wall about three inchs high. I found that in order to get the solder to flow (easy flo 45)
    I had to use a moderate size tip (O/A) to get enough heat to flow. I was under the impression that propane was likely the best heat source for this but I had to use what I had. Suggestions?

  • #2
    Copper is such a great conductor that it pulls the localized heat away pretty fast--so you probably had to get the whole piece pretty warm. While not huge, that size pipe would probably be a chore to silver solder with any of the smaller propane and oxygen setups. I have one of the mini ones and it has its place. I prefer the oxy-actylene in most instances though.

    Comment


    • #3
      I was reading in another thread just today about the CO2 is low in a propane flame and does not sheild the weld like AC.

      I have only gas welded with acetylene so when other chime in I will learn a few things too..

      I have welded hydraulics with brass but never silver solder, it seems to me I remember being told silver solder likes about 1,850F and propane just kick out about 1,600F its just too cold. Please correct me if I am wrong...

      Comment


      • #4
        Originally posted by tattoomike68
        it seems to me I remember being told silver solder likes about 1,850F and propane just kick out about 1,600F its just too cold.
        Silver brazing is usually done around 1145° F, well within the heat envelope of oxy/propane.
        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

        Comment


        • #5
          The correct way to silver solder a large piece of copper like that (or silver!) is to flux the area to be joined and then, using the flux as glue, stick small pieces of solder ribbon in the area sufficient to flow out when it melts. The entire piece must be heated. Easyflo comes in several different grades, each with a different melting temperature. If you have several different parts to solder on the same piece you start with the highest temperature grade first. The next soldering operation is done with a lower temperature grade and care is taken to just heat the piece enough to melt it without melting the previous joins. This can be repeated if you have a selection of solder grades.

          I highly recommend buying silver solder in ribbon form as it is much more versatile than sticks.
          Free software for calculating bolt circles and similar: Click Here

          Comment


          • #6
            Originally posted by tattoomike68
            Nice website, Mike - somehow missed it all this time.

            Comment


            • #7
              Originally posted by dp
              Nice website, Mike - somehow missed it all this time.
              I am the tech admin of that site, I dont have the skills to even think of building engines as fine as they do but am proud to make the site a fine place.

              I can write code for web servers but someday as an old man I will build some more engines, I just hope I live long enough.

              Since I hurt my back and my heath went downhill I started working on web sites and I spend less time in the shop.

              You are all very welcome to join http://www.homemodelenginemachinist.com/ and watch videos and download plans and enjoy for free, its a place where we have fun and are easy going.

              thanks for noticing its nice, We worked hard setting it up.

              Comment


              • #8
                Mapp gas

                In a former life I built bicycles (or human powered vehicles at any rate)
                always brazed with Mapp gas (basicly propane++) / O2
                and used a borax flux paste.
                seemed to always work well
                --
                Tom C
                ... nice weather eh?

                Comment


                • #9
                  My turn,

                  You mentioned Easy-Flo (not Sil-FOS). It's 45% Si, 15% Cu, 16%Zn and 24% Ca (note the zinc and cadmium ... good ventilation needed). There is a very fine line between its melting point (Solidus 1125 F) and when it flows (Liquidus 1145 F). Your flux must be fresh and clean. We only use Borax made into a paste with distilled water, which of course you can buy (don't use tap water to thin the Borax). The copper must be super clean. Heating is critical. The flux is your friend, acting like a temp-stick. When you start to apply the heat, the flux will dry out (moisture i.e.) boils off (212 ish). The flux will then turn a milky white in color and start to bubble at about 600 degrees. Eventually it will turn into a clear liquid at about 1100 degrees, which is just short of the brazing tempeature. Keep in mind its melting tempeature and when it flows, about 1140 F. A large tip is best as it allows for a shorter brazing time and reduces the time for oxides to form. On larger bore copper tube (6" and 8") we use a double headed tourch and or a large rose bud, sometimes 2 of them.

                  -SD:
                  Last edited by Smokedaddy; 07-15-2008, 02:11 AM.

                  Comment


                  • #10
                    Originally posted by Astronowanabe
                    In a former life I built bicycles (or human powered vehicles at any rate)
                    always brazed with Mapp gas (basicly propane++) / O2
                    and used a borax flux paste.
                    seemed to always work well
                    thats cool I have a few old bikes and would love to make a bicycle built for 3. 2 is too easy...

                    Comment


                    • #11
                      Not so fast. Easyflo 45 is just one of the series that may be used.

                      Filler Metal name: Easy-Flo 45
                      Typical Applications: Joining ferrous, nonferrous and dissimilar metals and alloys with close joint clearances.
                      Solidus: 1125'F/605'C
                      Liquidus: 1145'F/620'C
                      Max. Recom. Brazing Temp. 'F: 1350
                      Nominal Composition,%: 45Ag 15Cu 16Zn 24Cd
                      Joint Color as Brazed: Light Yellow


                      Filler Metal name: Easy-Flo 35
                      Typical Applications: Similar to Easy-Flo 45, but used where joint clearances are large and fillets are desired.
                      Solidus: 1125'F/605'C
                      Liquidus: 1295'F/700'C
                      Max. Recom. Brazing Temp. 'F: 1400
                      Nominal Composition,%: 35Ag 26Cu 21Zn 18Cd
                      Joint Color as Brazed: Light Yellow

                      Filler Metal name: Easy-Flo 30
                      Typical Applications: Similar to Easy-Flo 35, but used for more economical joints.
                      Solidus: 1125'F/605'C
                      Liquidus: 1310'F/710'C
                      Max. Recom. Brazing Temp. 'F: 1400
                      Nominal Composition,%: 30Ag 27Cu 23Zn 20Cd
                      Joint Color as Brazed: Light Yellow

                      Filler Metal name: Easy-Flo 25
                      Typical Applications: Similar to Easy-Flo 30, but used for most economical joints.
                      Solidus: 1125'F/605'C
                      Liquidus: 1375'F/745'C
                      Max. Recom. Brazing Temp. 'F: 1400
                      Nominal Composition,%: 25Ag 35Cu 26.5Zn 13.5 Cd
                      Joint Color as Brazed: Light Yellow


                      Note the differences in liquidus temperatures. It is a stepped series intended to be used in the manner I described. There is a lot more to silver soldering than just melting a bit by putting a flame to it. It is possible to do some very intricate soldering by taking advantage of the properties of the available filler metals.


                      There is a very fine line between its melting point (1225 F) and when it flows (1145 F).
                      1225 isn't the melting point. The liquidus of Easyflo 45 is 1145 and the solidus is 1125. Because Easyflo 45 is not a eutectic it does not melt or solidify all at once. The two temperatures give the range between which the solder is neither entirely solid or liquid. At the solidus all components have solidified. At the liquidus all components have melted. With a eutectic mixture all alloy components melt and solidify at the same time and temperature.
                      Free software for calculating bolt circles and similar: Click Here

                      Comment


                      • #12
                        Hi Evan,

                        Oops, a typo on my end, meant 1125. I suppose I should start reading my own posting before saving. <duh> I teach welding and brazing too. <red-faced> I realize additional series exist, he was specifying the 45 series.

                        Regards,
                        -SD:
                        Last edited by Smokedaddy; 07-15-2008, 02:21 AM.

                        Comment


                        • #13
                          Why not use soft solder

                          Since its for a fuel tank, fairly low pressure, why not use soft "plumbing" solder. Most melt and flow at 500 deg or less, easy to work with, flows nicely, easy to clean up, and designed for joints that hold liquid.

                          Mike
                          Mike Hunter

                          www.mikehunterrestorations.com

                          Comment


                          • #14
                            caddy, we can't use heat and temp interchangeably....propane and air give plenty high enough temps to silver solder, I do it all the time, but for a big job it doesn't provide enough heat (energy) in enough time. if you had 5 guys going at it with large propane torches no problem...or use O/A that puts out a whole bunch more heat a lot quicker. An A/O flame is too high temp for silver solder, it can burn the flux, so when using A/O its best to apply the flame indirectly
                            .

                            Comment


                            • #15
                              McGyver, post some more silver brazing pictures -- some of the brazing jobs you've posted are amazing.
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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