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A Riveting Question

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  • A Riveting Question

    I'm still trying to build a copper boiler and having trouble with my test joints. It is an overlapping joint held together with rivets and of course silver solder. In my tests I now have solder flowing all through the lap joint, but not up into the rivet holes. The rivets are pressed in pretty tight and I'm afraid there just isn't enough room for the silver to flow. Yes, the rivets and holes are very well fluxed. I bought flux and silver form Coles and it is made for this kind of work. I am considering tinning the rivets which will make them softer for pressing but I don't know how to do it to hundreds of rivets. Maybe I should tinn the the actual rolled sheet. Maybe it isn't important that the rivets be held with solder at all. I just want to get this right and build the safest boiler possible. Help!!

  • #2
    Why are you using rivets?
    On a small boiler, silver solder will be plenty strong for reasonable pressures.
    I am referring to Kozo Hirakoa Building the Climax, 3/4" scale. He uses rivets only when necessary to hold sub assemblies together while silver soldering. He advises to keep rivets to a minimum to minimize possibility of leaks.
    To get silver solder to wick into joints, there must be enough clearance. Installing rivets, and setting them closes these clearances up.
    Your boiler should be safe with silver solder. You are going to hydro test it to prove safety before use, so I would be more concerned with a good silver solder joint.
    If your plans call for the rivets, you might want to talk with designer.
    If you have doubts, make a simple cylinder, closed at the ends, and hydro that.
    Jim H.


    • #3
      The plans call for rivets. If I didn't put them in to build it, I would have to install fake ones to match prototype. Also, The shell is nearly 24 inches long, and I don't know how I would be able to keep the lap joint tight for soldering without the rivets.


      • #4
        Try a small piece of solder in with the rivet. If the Silver solder is too big you can try rolling it into a ribbon or hammering flat and slicing into strips. Silver solder filings could also be used - jewellers use this tricks with Silver, Gold, and Platinum. One company used to make a paste - it was just flux and powdered silver solder (TIX brand, I believe).

        Good luck with your boiler.