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Thread: Help with soldering or brazing sheet brass

  1. #1
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    Question Help with soldering or brazing sheet brass

    I've only had experience soldering small pieces of brass together using a Big Shot GT8000 torch and easy silver solder and Dandix paste flux. Now I've designed a box to be (hopefully) constructed of 18 gauge brass, with the largest piece being 3 x 4 inches.

    I've been trying over and over to solder the pieces together using a blow torch with MAPP-propane combination fuel. I think the pieces should be hot enough for the solder to flow, but it beads up and won't flow.

    There's information online telling about brazing brass sheet with brazing rods and flux, and I wonder if anyone knows if this would be a better approach. If so, can someone advise what products might enable me to join the brass sheet? Is these any particular solder and flux that might be better to use? Cost is an issue, so I'm hoping I can be frugal.

    Any help will be much appreciated.
    Last edited by Rumunda; 11-11-2019 at 02:19 PM. Reason: added the idea of better flux and solder to question

  2. #2
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    Looking at pictures of the torch, I'd be surprised if it puts out enough heat to do the job. You can help it along by boxing things in with soft firebricks, but I don't think it'll be enough.
    How much soldering (or brazing) have you done before?

  3. #3
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    Default My level of experience

    Thanks for your reply. Do you mean the Big Shot torch? If so, I think you're right that it isn't enough to bring the brass up to the needed temperature. However, I've been using a Benzomatic torch tip with a cylinder of MAPP-propane combination fuel, and easy silver solder and Dandix flux. I've tried to upload an image of the torch tip I've been using attached to the gas cylinder, and hopefully I did it right. The flame gets pretty bright and hot whereas the Mapp-propane combo burns hotter than plain propane. It burns at 3600 degrees F.

    Click image for larger version. 

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    tip shown above is about 6 inches or 15.5 centimeters long

    I've only has experience taking one metal smithing class many years ago, but in recent years I've been soldering steel alloys, brass wires to form sculpture, and most of the things I've soldered have been small scale. I also took a welding class years ago, but have no desire to work with high voltage, nor would the place I'm living allow a rig with an oxygen tank and a gas tank. This includes the impossibility of even a small pair of tanks, so I'm stuck probably using the Benzomatic gas and tip. To simplify, I'd consider myself a somewhat advanced beginner, but I lack knowledge about the different fluxes, appropriate solders for specific jobs, and brazing metals together.
    Last edited by Rumunda; 12-11-2019 at 01:33 AM. Reason: added info about the length of the torch tip

  4. #4
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    As Peter said you will be struggling with that torch, I f I need to solder brass of that size, I don't even use my little torch, I use my oxy/acetylene welding equipment.
    Brass is not as straight forward as Silver or gold if you heat brass for too long or over heat, zinc can rise to the surface an cause the solder not too flow, you need to be able to bring it up to temperature quickly, and not hold it there
    for a extended amount of time
    Last edited by china; 12-11-2019 at 06:36 AM.

  5. #5
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    I'd be inclined to use my Sievert (fuel/air) with a decent size tip or the Flamefast (fuel/compressed air). I'd still try to box it in though.
    I think I've got that Bernzomatic somewhere.

    As for flux & solder - I don't see an issue with the ones you're using, although there are lower temperature silver-bearing brazing alloys around. Silver-Flo 55, for example, has a melting point of 630-660C. I'd still use the bigger torches with it though.

  6. #6
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    Thanks for the information. Excessive, prolonged heating time has likely risen to the surface of the brass I've been trying to join. Can it just be removed with some emery paper to start fresh? Maybe I could get a Benzomatic gas and oxygen rig to create sufficient heat. I've looked at their website, and it seems they might sell something suitable. I also contacted them to inquire about what item from their product line might do the job.

  7. #7
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    Thanks for you reply. I looked at the website for Seivert products, and I'll have to try and figure out 1) what compatible parts I'd need, e.g., hose, tanks, etc., and 2) whether I can afford it. I'm really determine to complete the piece one way or another, so I might invest in something. I've been using metal flat head tacks to secure the pieces to be joined onto a magnesium block. I figure that should ensure a right angle and stability when soldering. I wonder if a charcoal block might help increase the heat.

  8. #8
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    https://www.harborfreight.com/propan...ers-91899.html + one propane tank. Not a Sievert, but a significant step up from a hand-held torch.

  9. #9
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    Thanks for the link. The price is very good, too.

    I saw your work an Facebook, and it's great. The mokume gane pieces are especially beaiutiful.
    Last edited by Rumunda; 13-11-2019 at 09:55 PM. Reason: added comment about work on Facebook

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