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Thread: LEAD BALLAST CASTING with cast iron tub

  1. #1
    Join Date
    Dec 2012
    Posts
    15

    Default LEAD BALLAST CASTING with cast iron tub

    Hello

    i am in the middle of the process of casting my lead ballast for Atkins' Economy Jane. It is not a huge cast, 815 lbs.

    my question relates to using a cast iron bath-tub which i have researched and found to be a common pot to melt lead in. we had our pipe elbow system set up, to tip the pipe down into the burried mold once the lead was completely melted but had a leaking failure early on before all was melted so we shut down the fire. the seal we made with washers was not tight enough around the drain hole for the bath-tub.

    there must be a common fix for this problem. what kind of hardware and drain have people used in the past? we are not able to weld anything to the cast iron so it needs to be a bomb-proof seal.

    thanks kindly! this is urgent as i hope to attempt again soon.

  2. #2
    Join Date
    Dec 2001
    Location
    Northern NSW Australia
    Posts
    38,368

    Default Re: LEAD BALLAST CASTING with cast iron tub

    I've done one moderately large melt and pour, 5600 pound but used a steel hotwater cylinder. I could weld on standard plumbing fittings to the steel , some thing you can't do with cast iron... as you mention. The other consideration is that bathtubs are cast in high silica cast iron and it is a particularly brittle metal. You should be fine with the relatively small pour but avoid all sharp impacts , if it cracks it may fail completely. All I can suggest with the iron bath is boring 3 or 4 holes through the bath and through a matching flange , putting stove repair clay between the two and pulling them together...GENTLY with 1/4" nuts and bolts. Such an arrangement will weaken the bath slightly but should produce a leak proof joint.

    I'm afraid I don't have any photos of the valve but it's a short taper of steel on the end of a rod, the taper fits into a matching hole...not a tapered hole. I put a bit of mud in first then bedded the taper. When the lead was melted I lifted the arm pulling the taper. The taper is useful for slowing the flow should you need to.



    Here's the same pot in use on another ballast keel.

    Try to work out what the marketing guy wants you to do then do precisely the opposite.

  3. #3
    Join Date
    Dec 2000
    Location
    Nelson, B.C. Canada
    Posts
    2,132

    Default Re: LEAD BALLAST CASTING with cast iron tub



    I removed the old copper drain fitting and replaced it with a common threaded iron flange to take a 3/4” water pipe. The flange had an outer nut and the whole thing was fastened together and caulked with fireproof “rope” and firebrick cement. No holes were drilled into the tub. To release the lead, all I had to do was unscrew the pipe and let it flow. It worked like a charm, but the 1” diameter hole turned out to be too big and it allowed the lead to flow much faster than I wanted it to. We could stem this a bit by resting the end of the pipe in the hole to restrict the opening, but ideally I should have cut a 1/4” x 3/4" notch into the end of the pipe so that I could have better control over the flow of the lead as I unscrewed the pipe. (Zoom in for a closer look at the flange and pipe.)



    A simple U shaped metal channel did the job. No elaborate piping was used. No leakage problems.

  4. #4
    Join Date
    Dec 2012
    Posts
    15

    Default Re: LEAD BALLAST CASTING with cast iron tub

    wow! thank you so much you two for the support as well as the photos. great advise. i just purchased another 40 pound block of lead and am prepping to do the pour again tomorrow.
    i will let you guys know how it goes
    cheers!

  5. #5
    Join Date
    Dec 2012
    Posts
    15

    Default Re: LEAD BALLAST CASTING with cast iron tub

    hey guys!
    thanks for the help and advise. i chose to go route of using a steel tank so i could weld everything. i happened to have an old water tank heater laying around the farm. this way i did not have to buy more material (to seal the bath-tub) all turned out well. the top surface of the lead had some good geography due moisture in the wood.
    check out the video!
    http://www.youtube.com/watch?v=WW4majILUJo

    cheers

  6. #6
    Join Date
    Sep 2010
    Location
    Melbourne, Australia
    Posts
    1,083

    Default Re: LEAD BALLAST CASTING with cast iron tub

    Good video thanks guys. Did you allow anything for shrinkage when you made up the mould if so how much and was it enough?
    Last edited by andrewpatrol; 05-22-2013 at 09:32 PM.

  7. #7
    Join Date
    Dec 2012
    Posts
    15

    Default Re: LEAD BALLAST CASTING with cast iron tub

    yes i did allow for shrinkage.
    check this out
    http://www.kastenmarine.com/_pdf/mbqMetRef.pdf
    coefficient of thermal expansion for lead is 0.0000163.
    my length of 84" shrunk aproximately 1/2". the width and heighth of 6" and 4" had negligible shrinkages. good luck!

  8. #8
    Join Date
    Sep 2010
    Location
    Melbourne, Australia
    Posts
    1,083

    Default Re: LEAD BALLAST CASTING with cast iron tub

    Thanks Grundy

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