Brazing Fixture

Discussion in 'Tips and Tricks' started by srobovak, Feb 3, 2019.

Help Support HMEM by donating:

  1. Feb 3, 2019 #1

    srobovak

    srobovak

    srobovak

    New Member

    Joined:
    Mar 7, 2012
    Messages:
    2
    Likes Received:
    0
    Hi HMEM,

    First of all thanks for this great platform - a huge source of knowledge and inspiration to me.
    After sneaking around for a long time I thought I might also share something.

    Recently I needed a small 3-way fitting for my hydraulic line. I decided to braze one using some small (OD=4mm) hose nipples from Swagelok. This small assembly posted an obvious problem how to hold the pieces together during the brazing process so that they don't move. The idea here is to show you the little jig I used to hold everything together that worked quite well.

    In my experience proper brazing jig needs to meet three requirements:

    1) It has to have low heat conductance not to take much heat from the workpiece and hence keep the
    brazing time as short as possible.
    2) It has to be stable enough so that the parts don't move on you while brazing.
    3) It can't introduce too much pressure, otherwise the parts will deform during the heating process.

    These conditions are somewhat contradictory so it takes some time to design a proper fixture. And of
    course the build of such fixture usually takes much longer that the parts in question or the brazing
    process itself...

    Following photos show the individual parts, assembly held in fixture, brazed assembly and finally cleaned up finished 3-way fitting.
     

    Attached Files:

  2. Feb 3, 2019 #2

    DJP

    DJP

    DJP

    Well-Known Member

    Joined:
    Dec 7, 2012
    Messages:
    427
    Likes Received:
    110
    Nicely done. I might have tried brazing one nipple at a time to get easier access to each joint. A jig is certainly preferred and now you can make hundreds.

    Thanks for sharing
     
  3. Feb 3, 2019 #3

    tornitore45

    tornitore45

    tornitore45

    Well-Known Member HMEM Lifetime Supporter

    Joined:
    Jan 17, 2009
    Messages:
    608
    Likes Received:
    90
    Clever.
     
  4. Feb 3, 2019 #4

    abby

    abby

    abby

    Well-Known Member

    Joined:
    Apr 14, 2009
    Messages:
    387
    Likes Received:
    103
    Making a jig seems a lot of work for such a job as shown , why not simply make the nipples a push fit into the block and they would stay in position whilst being brazed ?
    Dan.
     
  5. Feb 4, 2019 #5

    srobovak

    srobovak

    srobovak

    New Member

    Joined:
    Mar 7, 2012
    Messages:
    2
    Likes Received:
    0
    Dan,
    For a proper brazing action one needs about 0.05-0.1 mm gap for a capillary action to take place for this work's diameter. If press fitted, the silver solder has nowhere to flow. Moreover, by heating the whole thing above 720°C it could still end up crooked.
    But you're right it's not very efficient work for one part. I guess you could try it the way you described, but I think the joint would not be sound. - Brano
     

Share This Page