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Thread: Suggestions of new foundry

  1. #1

    Suggestions of new foundry

    I'm new to the forum. So first I have had experience with some aluminum melting and casting using plaster of Paris/sand furnace. After a few good melts it's garbage.

    So I'm looking to build something with a bit more life. So I live in Newfoundland, Canada and its extremely hard to find a proper refractory mix and online shipping cost is crazy for the weight. So I can easily get my hands on some wood furnace firebricks rated for 2200f to 2600f depending on vendor.

    So the idea is to do a hexagon with the bricks inside a cylinder and possibly fill the void around with the 4:1 perlite:furnace cement mix. The bottom would have a 1 inch of the mix and 1-1/4 bricks and the sides will be 6, 9x4.5x1.25" bricks standing high. The sides will have between 1/2" to 1/14" of the mix.

    I'm looking to mainly melt aluminum and I have a waste oil burner that I used previous. So I'm wondering if this would be sufficient to my uses or a waste of my time? Any help would be appreciated.

  2. #2
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    I made a fire brick furnace using hard fire bricks from a local store.

    It works well. I used a layer for the base, then stacked them in a circle and banded around them with heavy wire.
    A little furnace cement at the joints.
    I knocked a hole in one for the tuyere.

    Works great for aluminum melts with a #10 crucible and propane.
    Hard fire bricks will stand up to an oil burner pretty well too.

    If the pieces of scrap I am melting are unusually tall (like old runners and sprues), I stack a layer of half bricks around the top to extend the furnace upwards.
    The lid is a piece of kiln shelf. Just leave a gap at one side as the vent.
    Some people use insulation around the bricks but I don't even bother with that, but it would be a little more efficient with insulation, but it works fine without insulation.

    I use half a brick for a plinth.

    This is makes an inexpensive lightweight furnace that holds up well over time even with oil, can be made in a couple of hours, and is often overlooked by the do-it-yourself refractory guys here.

    Here is a recent thread on this topic.
    http://www.alloyavenue.com/vb/showth...+brick+furnace


    Edit:

    I would suggest purchasing your crucible first, and then lay out the fire bricks around that, leaving approximately a 2" space around the crucible for a #10 crucible (more space for a larger crucible, perhaps a little less space for a smaller crucible).
    Be sure the space around your crucible will allow you to insert your lifting tongs into the furnace. (Lifting tong sizes vary).
    For oil burners, a little more space works better.
    Morgan Salamander Super (iron and ferrous-metal rated) crucible sizes are shown below.

    The hard fire bricks I used were from Tractor Supply, and were 4.5" x 9" x 1.25" in size.
    I have tried soft fire bricks, but they do not hold up well for higher temperatures and will crumble if used at temperatures that an oil burner will produce.

    A #10 crucible sitting on a 1.25" plinth (half a fire brick) will fit height-wise with a 9" tall brick.
    An crucible larger than a #10 will need a second row of bricks to extend the height of the furnace above the top of the crucible at least an inch or so.

    I beveled the sides of my bricks with a carbide disk in an angle grinder (use a dust mask for sure, don't trash the lungs).
    You could also just chamfer the edges of the bricks about 1/4", or don't use any bevel or chamfer since that would also work.

    My tuyere diameter is about 2", but you can go smaller than that for this size furnace/crucible.
    The centerline of the tuyere should be at the top of the plinth that the crucible sits on, and the tuyere should enter the furnace between the crucible and the furnace wall so as to avoid direct impingement of the burner flame on the crucible.

    The photos below show the furnace in use with and without the height extension bricks.
    I do not secure the extension bricks when I use them.
    Attached Images Attached Images
    Last edited by cjcaster; 03-15-2017 at 08:49 AM.

  3. #3
    That was my intentions exactly but I was only planning to use 6 but I might just go with 8. Does anyone know if this would hold up to brass or copper temps using 2700f furnace cement and a couple layers of ceramic blanket?

  4. #4
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    This furnace pictured above is so good as an alternative, not only for those folks who cannot get castable refractory, but for all of us, that I made it a sticky.



    Especially for an oil burner, this makes total sense. And everything is available at your beloved big box stores (as much as I hate to promote them).

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  5. #5
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    Does anyone know if this would hold up to brass or copper temps using 2700f furnace cement and a couple layers of ceramic blanket?
    I would recommend that you stay away from perlite; it will melt at bronze temperatures. Just use the furnace cement. That's what it's for: patching cracks.

    If you really crank up your oil burner the way I do, the firebricks may take a bit of a beating where the flame hits them, but that would take a good while and it would be easy to replace a few bricks.

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  6. #6
    Senior Member Robert's Avatar
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    My first furnace was hard firebrick. It is overlooked as a resource to get up and running fast.
    Robert
    "Whether you think that you can, or that you can't, you are usually right."
    - Henry Ford (1863-1947)

    Forklift Project
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  7. #7
    I don't think my burner would have any problem melting copper I have had it melted before using a cutoff propane tank as a foundry with no insulation and no lid. It wasn't to the point of pouring but it was melted.

    I think I'm gonna go this route and use 6 bricks standing tall. That still give me a inside diameter of 7.8". So I would still be able to melt over 10 lbs of aluminum in it. I think I may put it in a propane tank and fill it around with play sand. Mainly to protect it from damage of moving it around. Do you think this would cause any problems? Also do you think a inside dial of 7.8" would be fine?

  8. #8
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    As long as your still in the planning stage maybe you'd consider 10" or so. Oil likes room to burn . My first furnace was about 7.5" and from the first time I burnered oil in it I wished it was bigger. My new one is 10" and I'm quite pleased. If you use hard firebrick it will get heavy but will be bulletproof.
    Welcome to the forum.

    Pete

  9. #9
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    Instead of just sand, you could use a mix of 1/3 clay and 2/3 sand (any kind of clay will do). Mix the dry ingredients well. Then wet the mix just until you will form a ball in your hand when you squeeze it. Let it sit in a plastic bag for a few days and then ram it in hard with a stick. Let it dry and then fire the furnace for an hour or so to fire it. it will be strong and will hold everything together solid.

    Just sand would work too. It just wouldn't be as solid a mass. It ain't rocket science. The only really important thing about furnace construction is that the furnace walls and the lid don't melt.

    Richard
    When I die, Heaven can wait—I want to go to McMaster-Carr.

  10. #10
    Quote Originally Posted by CoJax View Post
    That was my intentions exactly but I was only planning to use 6 but I might just go with 8. Does anyone know if this would hold up to brass or copper temps using 2700f furnace cement and a couple layers of ceramic blanket?
    with the insulation it would probably even handle iron temps. definitely brass or bronze. Petes comments about oil needing room for combustion is very important, if it is burning outside the furnace you you have more fuel than room in the furnace or more fuel then combustion air. and are just wasting fuel. and you could even be running cooler temps in the furnace if you are over firing to much.

    Art B

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