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Thread: Cheap foundry build for melting steel

  1. #1

    Cheap foundry build for melting steel

    This is my first time posting, and my first build. I'm trying to build a foundry to melt steel for casting, but mainly for making ingots for knifesmithing. Its a small build, and I was looking for feedback to see if it would work safely, and for any improvements I could cheaply apply.

    The build is about 9x8x9 with a lid of 9x9x2. The walls are firebrick held together with angled steel/stainless. A fan from a bounce house attached to a stainless steel pipe would put the air in, and propane would be put into the steel pipe up by the fan, hopefully to avoid possible explosions, if I need to worry about that. A small 8 kg graphite crucible to melt in.
    The firebricks:
    The crucible:
    Please let me know what you think!

  2. #2
    Welcome to the forum. I suggest you read around a bit first. Melting steel is a challenge with conventional fuels and is not a process which is easy to do on a small scale. If you're really set on steel, check out this thread

    I do not know of any other member here who has a setup capable of producing molten steel, let alone casting it reliably. Read around and you will find that cast iron is a good metal for a foundry.
    Use those coffee makers with the spout out the bottom to preheat you oil!

    My foundry:

    My waste oil burner:
    Metal casting video:

    My website :

  3. #3
    most steel melting is done using arc furnace, but usually done in something like an alumina crucible. The clay/graphite one will start to get soft at steel temps and the steel will absorb the carbon right out of the crucible, turn it into high carbon steel at best, or into cast iron. It's very very difficult to actually do cast steel on a small scale because you need some way to keep the carbon content to a precise level.

    I wouldnt even mess with trying to melt steel because it's extremely difficult next to impossible for the home gamer. Also, propane, even forced air propane wont get hot enough to melt steel. I'd honestly just go buy the stock you need and just forge that.

  4. #4
    Why oh why does everyone want to melt steel? I've participated in an attempt to make wootz steel about 5 or 6 years ago at a buddy's place. He had taken a class with Ric Furrer on the subject and bought the setup they used in the class. It consisteyd of a steel shell lined with kaowool coated with satanite. It used a blown propane burner, and hate to disagree with you cae2100, it had no problem getting to temp. Sounded like a jet engine. We were using a silicon carbide crucible for a roughly 4lb charge of material. It took about 4 hours and we went through 2/3rds of a 100 lb propane tank. We also had to destroy the crucible to get the puck of steel out. A brand spanky new crucible, by the by. Made me cringe a bit.
    The upshot of this is that it is a very expensive way to make steel of questionable chemistry and carbon content. From what I understand crucible steel is also very finicky and difficult to work. I get the desire to try something just to say you did it as a once ot twice thing. If you want to do it as an ongoing thing you may want to rethink, unless you have a really cheap source of crucibles. I suggest you look up Ric Furrer's website, Door County Ironworks or something like that. See if he is giving a class near you.
    You are also going to be going through some firebricks too. Be prepared to rebuild your furnace a lot. Depending on the size of the charge of steel you want to run you are going to have to hold it over 3000F for hours at a time. Unless those bricks are rated to 3500F or so you are going to wind up with a glassy pile of slag instead of a furnace.
    You want to try, go for it. Understand, Grasshopper, the mountain of knowlege you wish to climb is steep. And expensive.
    Vade Libram Harenae.

  5. #5
    ho hum......... Knives are forged. Never cast. Well, maybe the space age ginsu 9000 might be cast cat turds.
    Visit me:
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    -- Donald Trump --

  6. #6
    Senior Member
    Join Date
    Aug 2012
    Hinchinbrook QLD
    Well the OP did say he wanted to cast ingots for knife making, so technically you could still forge them out. But the steel quality would be a definite unknown

    Cheers Phil
    So, whats your Plan B?

  7. #7
    Using a kaowool lined furnace insulates even better. No refractory needed.
    And kaowool is relatively cheap, so after a few sessions, some inner wall parts which are overheated can be easily patched (use a respirator due to fine dust and PM !).
    I have a furnace of about the same size (a paint can lined with kaowool which melts cast iron).
    See attached photo, this furnace (7" outer diameter, 7" outer height, 3.5" ID, 4" inner height, two layers of 1" kaowool) is used over 20 times, mostly for copper but the last time for cast iron where the inside got over 1500 C. It lasted only 15 minutes to melt 15g of cast iron starting from a cold furnace / crucible. The arrow is the burner entry and opposite (encircled) is where the kaowool is damaged by overheating. A simple patch fixes this.

    Steel can be molten on propane+forced air, but the crucible is indeed the issue.
    I melted tiny (about 80-100g / 3oz) amounts of stainless in a pure graphite crucible with electric arc. It indeed picks up carbon from the crucible.
    But how do commercial steel works do this ? The steel is indeed held in a watertight (steeltight) refractory shell and not a graphite crucible, but they do use carbon rods running the arc which also introduce C into the steel.
    I tried Hessian crucibles but they crack very easily.
    Are alumina or SiC crucibles reliable or do they break when you watch it ?

    EDIT: I just patched the overheated part with success. It felt like molten and frozen again plastic.
    Attached Images Attached Images

  8. #8
    Quote Originally Posted by GrantHavok View Post
    making ingots for knifesmithing
    If you are truly determined to cast stock for knives, check out these folks.
    There is an entire sub-forum for producing steel.

  9. #9
    ho hum......... Knives are forged. Never cast.
    Just came across this interesting article.

    somewhere in the middle it mentions a mold for casting copper daggers.


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