Melting the lead / fitting the bulb shape

Discussion in 'Boatbuilding' started by cuorefocoso, Jan 17, 2008.

  1. cuorefocoso
    Joined: Dec 2007
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    Location: Lithuania

    cuorefocoso Junior Member

    Hi
    What kind of expierence you guys have in melting the lead? I am trying to make a part of a bulb, approx 100kg. I see it will be not so easy to handle it as a single solid piece in preduction process. But what is divide it in parts - will it join to a even (solid) piece if three separate melts will be poured into a mould? I mean should they stick to each other?
    And afterwards, will the epoxy filler stick to lead to have a smooth and nice finish?
    All coments are welcome, these about home-made methods specially.
     
  2. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    I have not done big lead melts for years now, a bit smarter, older and wiser I like to think. However, last time we did a keel for a 32 footer in the shed we made a gas fire under a cast iron bathtub, just used those big BBQ or wok type burners, two of em, made a steel plug on a rod to fit the hole, melted the lead by throwing pieces in and letting them melt so that the temp did not get too cold too fast. We then let the plug out , rather controlled so as to not heat up too much into the mould in the dirt under the bath. It worked great, and was not really difficult at all.

    As for epoxy sticking to lead, yes, i have been very successful doing that using Altex Devoe products, I used their metal primer, then primer surfacer and finished off with their epoxy paint system. Have done this on many occassions in my old yard in Sydney, and never had a failure that I know about. I am sure I would have been told if there were any!
     
  3. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    oh, and keep away from the fumes of the melt, very dangerous. Doing it in the tub, we actually had very little gas rising that we were aware of.
     
  4. petereng
    Joined: Jan 2008
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    Location: Gold Coast Australia

    petereng Senior Member

    If you don't want to melt the lead you can get lead shot and make a mould for the bulb. Place a vacuum in the filled mould and draw in resin (like in infusion) to fill the voids. Sheres have a packing factor of over 94% if well packed so the volume loss is not much. Do some trials. If you have a mixture of shot sizes the packing factor is very high. Plus add your bolts and connections so they don't have to be done later.

    Cheers Peter S
     

  5. cuorefocoso
    Joined: Dec 2007
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    Location: Lithuania

    cuorefocoso Junior Member

    Good point, petereng.
    The only thing is where to find the shots? But in general it should be ok I think.
    I was "hunting" for good combination of lead vs. the price here for some 2 month I think; price varried some 5 times, starting on scrap (balancing weights on car wheels, you know what I mean), and finishing on raw sheets 2mm thickness, rolled. Finally I bought 5 pcs 20 kg each.
    Now gyus are cutting the steel plates to weld a mould.
    Then I am planning to make a fire under ths steel mould, and pour these pieces one by one, so there should be no layers of lead and no need to lift the whole bath with liquid lead. I guess it should work.
     
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