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Thread: Casting lead questions

  1. #71
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    Default Re: Casting lead questions

    Quote Originally Posted by Small boats rock View Post
    Another sealant which can handle molten lead temperatures is silicone, the stuff used for sealing up roof gutters etc.
    Construction grade silicone won't take the heat. There is one readily available high temperature gasket silicone that might be OK here.

    I was about to say that you would have to go to something like Pelseal liquid Viton because no silicone could handle the temperature. As much as I hate being wrong, one more check came up with Permatex 81160 High-Temp Red RTV Silicone Gasket Maker that is supposed to be OK to 650F while Pelseal is only rated for 450F. Between the high price, difficulty finding it and potential for toxic fumes, Pelseal is not the best bet.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  2. #72
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    Default Re: Casting lead questions

    Your first test will reveal a lot of information to you. But my guess, based on some experience, is that the lead won't release easily. If it doesn't, you'll have to build in draft or make two sides removable to aid release. I don't think you need to use furnace cement. A simple dab of plasticine clay will do the trick and is easily done before each pour. The first pour will heat the mold and you'll be good to go from there on.

    Jeff

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    Default Re: Casting lead questions

    I live and drink rum where other people vacation.

  4. #74
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    Default Re: Casting lead questions

    Quote Originally Posted by MN Dave View Post
    Construction grade silicone won't take the heat. There is one readily available high temperature gasket silicone that might be OK here.

    I was about to say that you would have to go to something like Pelseal liquid Viton because no silicone could handle the temperature. As much as I hate being wrong, one more check came up with Permatex 81160 High-Temp Red RTV Silicone Gasket Maker that is supposed to be OK to 650F while Pelseal is only rated for 450F. Between the high price, difficulty finding it and potential for toxic fumes, Pelseal is not the best bet.
    When I did my big pour, much of the lead was old roof flashing. Lots had big lumps of silicone stuck to it where attempts had been made to fix roof leaks. I thought it would just burn up, but no, it didn't burn, didn't melt, didn't change at all. The lead melted away and the silicone retained its original shape as though nothing happened. Later when everything was cool I picked up those bits of silicon and found it still nice and rubbery, stretchy, flexible, just as it is meant to be. I have not previously sealed a mould with it, but next time I pour some lead I will incorporate some silicone to see what happens, and will heed your caution about fumes by standing to windward.

  5. #75
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    Default Re: Casting lead questions

    Quote Originally Posted by Woxbox View Post
    Oh no, my secret plan revealed. It's true, I'm planning for the Waterworld future, where I'll be shaving bits of gold from the bottom of my ballast castings to survive the lawless, sunken planet.


    I live and drink rum where other people vacation.

  6. #76
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    Default Re: Casting lead questions

    Quote Originally Posted by Small boats rock View Post
    When I did my big pour, much of the lead was old roof flashing. Lots had big lumps of silicone stuck to it where attempts had been made to fix roof leaks. I thought it would just burn up, but no, it didn't burn, didn't melt, didn't change at all. The lead melted away and the silicone retained its original shape as though nothing happened. Later when everything was cool I picked up those bits of silicon and found it still nice and rubbery, stretchy, flexible, just as it is meant to be. I have not previously sealed a mould with it, but next time I pour some lead I will incorporate some silicone to see what happens, and will heed your caution about fumes by standing to windward.
    Good information. Thanks. I wouldn't count on any real strength at temperature, but as a plug for a very small leak, it sounds like it should work.

    I meant that any fumes from Pelseal were a problem. It is a fluorocarbon, so it can release HF and other really nasty things if it gets too hot. Most silicones are not fluorinated so the fumes, if any, wouldn't be as bad. I never met a fume I liked, but some are a lot worse than others. Avoid them all. There are fluorosilicones, but I doubt you can find them in a retail store.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  7. #77
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    Default Re: Casting lead questions

    Quote Originally Posted by Sailor View Post
    Could you not just pour some sand into that cavity so the lead can't get in? I'd consider packing sand all around the mould as well, to keep the lead in the shape required.
    Don't do it! The sand will float up all through the lead making it impossible to work with edged tools. Even drill bits.
    Don't ask how I know this...

  8. #78
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    Default Re: Casting lead questions

    Ha ha, reminds me about my concrete mould. Tried to make a weak cement mix by having a fair amount of sand in it. Well some places evidently had a bit too much sand, so when the ballast keel emerged it had patches with sand embedded on the surface. The fix was a cheap electric plane which I didn't really like anyway. Fairly hacked up the blades which had to be sharpened every 10 minutes. Got the job done ok.

  9. #79
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    Default Re: Casting lead questions

    Now here's a thing of beauty. 38 pounds of stability in my bilge. 500 plus to go. Big thanks to everyone's help here. I took your advice to heart and it paid off.

    1st ballast.jpg

    Here's the setup for the pour. After the lead was ladled in and fully cooled, I flipped the mold over. The square end started to drop right away so the end with the finger grab jammed. I put some bricks under the loose end to keep it from twisting out, tapped the sticky end of the inverted mold, and out she came.

    mold setup.jpg
    Last edited by Woxbox; 05-22-2019 at 05:35 PM.
    -Dave

  10. #80
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    Default Re: Casting lead questions

    Here what it looks like just after the pour, or ladling, actually. You can see how the lead cooled immediately, but the layers do appear to have bonded strongly. It was easy to get it up to the edge with minimal spilling. Shrink back was negligible, it being only 1-1/2 inches deep. And the stove cement sealed the joins without failure.

    1st pour.jpg
    Last edited by Woxbox; 05-22-2019 at 05:37 PM.
    -Dave

  11. #81
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    Default Re: Casting lead questions

    Nice. Steady, easy, safely as she goes and you'll get it done!

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  12. #82
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    Default Re: Casting lead questions

    Very nice, I like the built in finger grab.

    Given that the mold is steel, do you think it would also work as the melting pot? Just set the mold on the burner, fill with lead and watch it melt. Obviously more lead would have to be added as the initial amount melts and takes up less space. Then let it cool and you've avoided the pour/ladling and know it is one solid piece.

    Just an idea to skip a step if you are not in a rush to get them all made.
    -JP

  13. #83
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    Default Re: Casting lead questions

    Quote Originally Posted by jcpout2c View Post
    Very nice, I like the built in finger grab.

    Given that the mold is steel, do you think it would also work as the melting pot? Just set the mold on the burner, fill with lead and watch it melt. Obviously more lead would have to be added as the initial amount melts and takes up less space. Then let it cool and you've avoided the pour/ladling and know it is one solid piece.

    Just an idea to skip a step if you are not in a rush to get them all made.
    -JP
    I suspect the answer is yes and no. This particular mold has lots of surface area and cooling fins (or the equivalent) all around. I'd probably need a lot more flame to get it hot enough. But the bigger thing is, as I'm working it, I can let the last pour cool in the mold while the next batch heats up, which should keep things moving along. But yeah, if I wanted to do just one, I could give that a try.

    This brings another thought to mind. That plumbers pot I'm using is made to order. The flame sounds like a jet engine, and the pot cradle concentrates the heat around the pot every effectively. I'm still wondering how much propane it will take to melt 600 pounds. Any guesses?
    -Dave

  14. #84
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    Default Re: Casting lead questions

    Looks good. Much better than the Micro Keel that I mentioned before. You could waste gas and pretty up the surface with a torch, but hiding it under the sole is best.
    Quote Originally Posted by Woxbox View Post
    This brings another thought to mind. That plumbers pot I'm using is made to order. The flame sounds like a jet engine, and the pot cradle concentrates the heat around the pot every effectively. I'm still wondering how much propane it will take to melt 600 pounds. Any guesses?
    No idea. Could you weigh the tank before and after the next pour?

    I would use wood, but I have brush to burn and a place to burn it, so boiling syrup and melting lead come under landscape maintenance for me.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  15. #85
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    Default Re: Casting lead questions

    Quote Originally Posted by Woxbox View Post
    I'm still wondering how much propane it will take to melt 600 pounds. Any guesses?

    When I cast the keel for Emily Ruth, I first melted all the lead scrap in small batches just to get it all clean and weighed. That was about 600 pounds. I don't remember emptying a small cylinder. The kind I use on my grill.

    Jeff

  16. #86
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    Default Re: Casting lead questions

    Well, I have a 20 pound tank. I'll be happy and surprised if that can do the job. Then again, a tank like that can do a year's worth of dog's and burgers.
    -Dave

  17. #87
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    Default Re: Casting lead questions

    Quote Originally Posted by jpatrick View Post
    When I cast the keel for Emily Ruth, I first melted all the lead scrap in small batches just to get it all clean and weighed. That was about 600 pounds. I don't remember emptying a small cylinder. The kind I use on my grill.

    Jeff
    That made me think. (ouch) That isn't near as much gas as I would have expected. The heat of fusion and heat capacity of lead are lower than water, but I had to look up just how much lower. It takes 32 times as much heat to warm water and 15 times as much to melt water. To heat a pound (pint) of water from 62F to the boiling point takes 5 times as much heat as it does to raise a pound of lead by 650F and melt it. Melting 300 lb of lead takes as much heat as bringing 60 lb, (about 7.5 gallons or one cubic foot) of water to the boiling point.


    https://www.engineeringtoolbox.com/f...ls-d_1266.html
    https://www.engineeringtoolbox.com/s...ity-d_391.html
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  18. #88
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    Default Re: Casting lead questions

    I'm quite surprised at the heat requirements Dave. I would have thought it would take more heat to melt th lead than to boil water. And the volume of water compared to lead.... Interesting anyway.
    If one advances confidently in the direction of his dreams, and endeavors to live the life which he has imagined, he will meet with a success unexpected in common hours.
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  19. #89
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    Default Re: Casting lead questions

    Quote Originally Posted by MN Dave View Post
    That made me think. (ouch) That isn't near as much gas as I would have expected. The heat of fusion and heat capacity of lead are lower than water, but I had to look up just how much lower. It takes 32 times as much heat to warm water and 15 times as much to melt water. To heat a pound (pint) of water from 62F to the boiling point takes 5 times as much heat as it does to raise a pound of lead by 650F and melt it. Melting 300 lb of lead takes as much heat as bringing 60 lb, (about 7.5 gallons or one cubic foot) of water to the boiling point.


    https://www.engineeringtoolbox.com/f...ls-d_1266.html
    https://www.engineeringtoolbox.com/s...ity-d_391.html
    Interesting links, but there are some realities that they don't address when applied to the real world...

    since water takes the shape of whatever container it's put in... it makes the heat transfer from the container to the water significantly more effective than from the container to only the small bits of lead that are actually touching the container, which then have to melt fully before more lead touches the container and can melt... those who have melted lead will have no doubt noticed that it takes significantly more effort to "get the first bit started" than it does to melt those later pieces that you can simply drop into the melted puddle and watch shrink... so while latent heats of specific materials are an useful tool... they don't tell the whole "real world" story

  20. #90
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    Default Re: Casting lead questions

    Quote Originally Posted by Woxbox View Post
    Well, I have a 20 pound tank. I'll be happy and surprised if that can do the job. Then again, a tank like that can do a year's worth of dog's and burgers.
    The truth is I really didn't keep any sort of record and sometimes my memory is subject to error. But I'm positive that it wasn't a major issue and I didn't use more than one tank and part of another. Also interesting... it took surprisingly little wood (less than two wheelbarrows) burning to melt the entire 600+ pound batch when I did the actual keel casting. But it was a hot day.

    Jeff

  21. #91
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    Default Re: Casting lead questions

    Update: I've poured 7, and with each extraction I lose more of the stove cement. A couple of small spots in the mold opened, but the lead seeped through a bit, solidified, and made what seems to be a permanent seal.

    The castings do not release easily at the shaped end. My refined technique is to flip it over, rap it good with a hammer until the square end hangs out with enough room to slip in a crowbar, and then pry it out. I was concerned I might bend something out of shape, but so far it seems fine.

    One other observation. I said earlier that the shrinkage is negligible. It really isn't but because I keep ladling until it's full, I gave myself the wrong impression. The level does drop down noticeably as it solidifies.

    Now I need to find more lead.
    -Dave

  22. #92
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    Default Re: Casting lead questions

    Quote Originally Posted by Sailor's Brother View Post
    Interesting links, but there are some realities that they don't address when applied to the real world... they don't tell the whole "real world" story
    Given that one tank might do the job, and two tanks will definitely do the job, how hard do you want to work on a calculation that won't change the fact that you might need to refill the tank?

    Need more lead? https://philadelphia.craigslist.org/...891249075.html But I suppose that 2500 lb blocks are an inconvenient size.
    Last edited by MN Dave; 05-24-2019 at 02:44 PM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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