Can you braze an object made of brass?

Discussion in 'Fettling Forum' started by JonD, Jan 31, 2019.

  1. JonD

    JonD Subscriber

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    I hope the title is self explanatory.
    It has been kicked off by the lovely little blowlamp which @Thomas soldered recently.

    I was looking at that and thinking could it be brazed? Sadly my experience falls short.

    If it was an object made of moderately thin mild steel (like a car for example) I would know the answer.
    With the right gas nozzle and filler rod (no 'leccy welding here) I could fix it - might be ugly - but functional.

    I realise I have no idea if that could work with brass. Soft solder - yes. Silver solder -yes, I can see how.

    But could it be brazed? Which when the object is brass is the analogy to welding mild steel with a steel filler rod.

    I have some feeling it might collapse in a heap. What do others reckon?
     
  2. Tony Press

    Tony Press Antarctica Subscriber

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    @JonD

    I always use hard “silver solder” and a MAPP torch or “oxy-MAPP” to repair brass.

    Brass can be brazed. Here’s a guide to the fundamentals:

    Brazing Fundamentals

    Tony
     
  3. Thomas

    Thomas Subscriber

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    Brazing brass would actually be fusion welding, I had been considering using brass snare wire as filler but silver solder is much easier to work with. While filling a crack in thin brass the edges will ball up you need to then have the filler rod ready and near melting to bridge the gap. It is possible to accomplish a welded seam with a torch but much easier using the TIG process.

    The stresses that caused the cracking in the torch font from a lack of annealing will also cause the crack to open and push outward, I preheat the crack and tap it down with a small hammer before I start any repair.
     
  4. MYN

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    Of course the answer is a 'yes, you can'.
    Its more like hard soldering, with or without silver. You don't use a brass filler rod to braze brass. Brass filler rods are meant for brazing metals which have significantly higher melting points than brass, such as iron and steels.
    You would need a brazing alloy filler rod with a somewhat lower melting point than brass for the job. Normally, a MAPP torch would suffice but it takes longer to heat up the piece compared to an oxy-fuel torch.
    I normally use an oxy-acetylene welding torch for this. And, most critical, would be cleanliness on the piece as well as some practice. Brazing fluxes are available for the job too. Sometimes they are not necessary but normally they are.
    I have attempted to braze brass using brass filler rods, but its a tough one as one could easily melt through the brass piece and ruin everything. This is more like fusion-welding. Not recommended.
    Copper-Silver brazing alloy rods are better suited for this as it could work by capillary action. Fluxes could be used to ensure a clean, oxide-free surface for better wetting and capillary action during brazing. Some skills are necessary and only a fair amount of practice could enable you to do it properly.
     
  5. paparazi

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    Difficult but not impossible, I've done a fare amount of 'gas welding' steel rods on steel plate and brazing. A workmate of mine was pure genius at welding Aluminium (crankcases and housings) what a skill. Knowing the point of 'flow' with the sacrifice (rod) needing to be kept marginally hotter (through technique) compared to the receiving plate accepting that each needs to flow to blend. Other techniques are preferable.
     
  6. JonD

    JonD Subscriber

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    Thanks for all the replies. It sounds like it is difficult to gas weld brass then - but maybe not quite as hard as aluminium.
    I have tried doing that and it was a complete failure. Anyone who can do it deserves full respect.

    It was just something that I had bever seen discussed before. I am sure silver soldering and such techniques are perfectly adequate in most cases.
    I was just curious to know if brazing brass with itself was possible :)
     

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