Brazing

  1. Kram

    Kram Member

    Messages:
    624
    Location:
    Sussex
    [​IMG]
    Complete failure! I have brazed before but they were smaller parts. This was with a propane mix. I did put a cut up can around to keep some heat in, but wasnt enough, only about 600c
    I dont remember if mapp would be enough? Ive got a torch for it somewhere.

    Used borax flux, and some grade of silver solder, unsure what.
     
  2. gaz1

    gaz1 Forum Supporter

    Messages:
    8,871
    Location:
    westyorkshire
    map gas heats alot higher enough to turn the part red hot
     
  3. brightspark

    brightspark Member

    Messages:
    27,359
    Location:
    yarm
    get a grey soft breezeblock break it up and pack it round the job to retain heat then try again
     
    Parm likes this.
  4. pedrobedro

    pedrobedro Man at Matalan

    Messages:
    9,906
    Location:
    CX Derbyshire
    Were your rods ready fluxed ?
     
  5. Parm

    Parm I have fun doing stuff

    Messages:
    9,970
    Location:
    Towcester
    Did you look at internet first?
    Web is very useful but it don’t provide all the answers.

    Unless your a special few who specialise in regurgitating the web

    You’ll work em em out

    Their advice comes with zero experience
     
  6. Paul.

    Paul. Moderator Staff Member

    Messages:
    6,155
    Location:
    Northampton. UK
    You'll need to get that up to around 900deg C minimum to braze or hard solder it, Mapp or propane will struggle to pump that much heat into it, its really an Oxy acetylene job, why is it being brazed, take it somewhere and get it tigged, its a five minute job, probably cost you a tenner, (it would with me anyway).
     
    mtt.tr, Yamhon and Parm like this.
  7. optima21 Forum Supporter

    Messages:
    2,658
    Location:
    halifax, England
    if its silver solder its melting point can be anywhere between approx 600c and 850c depending on grade. borax doesnt melt until aprox 725c, so it may not have got hot enough.

    I use easyflo flux for most things as its operating temperature is between 550c and 800c and tenacity no5 for high temperature (600c to 900c operating temperature) silver soldering and its also used for silver soldering stainless steel which easyflo isnt recomended for.

    like you say you havnt got enough heat, as it doesnt look like the borax has melted properly as it still looks powdery.

    if you have a propane torch it should be hot enough if you have a big enough burner, and insulation to reflect the heat
     
    Parm, Hopefuldave, Gragson and 2 others like this.
  8. Kram

    Kram Member

    Messages:
    624
    Location:
    Sussex
    Got a can of map and found my torch. I remember one type of gas - proper mapp, or propane? would burn too far up the tube, so years ago I cut an inch off the end to prevent it getting hot, and worked great, knowing it'd need to be reversed for other fuel. The last can I used was a yellow mapp. This mapp replacement does not like that and needs the extra length for mixing, so Ill turn a new tube an inch longer. Would be useful to know which gas and why - I cant remember and suspect both are just different mapp replacements. A quick test with a bit of tube and it will mix and burn correctly when longer.
     
  9. Kram

    Kram Member

    Messages:
    624
    Location:
    Sussex
    [​IMG]

    Turning stainless was nice, ill use it more often! The length was part of the issue but more important it was getting too much air, made a bunsen style adjuster sleeve.
     
    Hopefuldave likes this.
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