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Advise On Making Forge

Discussion in 'Forges, Ovens, Kilns, & Salt Pots' started by Justin Zimmerlee, Feb 19, 2020.

  1. Justin Zimmerlee

    Justin Zimmerlee New Member

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    Hello,
    I just need a forge to heat treat for now and was going to make the coffee can one with plaster of Paris, I was wondering if it would be a good idea to coat it in refractory cement once it’s all dry
     
  2. dancom

    dancom Dust Maker Best Shop Tool

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    Hi Justin. Welcome to the forum.

    Refractory cement is always a good idea. It should save you on fuel over time. What are you using for a burner?

    Dan
     
  3. ToddR

    ToddR Putterer, Tinkerer, Waster of Time Staff Member

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    I did a small forge using a coffee can as well. I used perlite and sodium silicate with a refractory cement coating. The perlite/sodium silicate doesn't hold up if you don't. I've never used plaster of paris but I've seen many YT videos where it's used. Seems to last. I think they mix it with sand though too.

    Mine's held up really well but word of advice, give the refractory coating lots and lots of time to cure. I did a low heat on mine a bit too soon and lots of moisture bubbled up out of it. It caused a rough texture on the surface. Not the end of the world - still works but give it a good long time (like a couple weeks even) in a warm dry place.
     
  4. Griff

    Griff Active Member

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    Hi Justin, I made a small one using fire bricks, like the ones here:

    https://tuckerspotteryeshop.com/index.php/product/bricks-uncut/


    I sandwiched bricks together two at a time with refractory cement and let them set. I soaked them in water to keep the dust down (please still wear a dust mask or respirator, the dust from these are nasty), and used a hole saw, I think a 2 1/2”, and drilled all the way through, then did another refractory cement sandwich with the six bricks, lining up the holes of course lol!

    I then drilled two holes at an angle from the bottom left and right sides, so as to angle two MAP torches into the circular chamber. I think two torches was over kill, and the MAP gas got it so insanely hot it melted the tips of the torches!
    [​IMG]

    I used this to heat treat (not forge) my first 3 O1 tool steel knives to great effect. The bricks were 3” thick, so I ended up with a 9” chamber. Mine was based loosely on this one in Aaron Gough’s video, notice he only uses one torch and regular propane haha. So his would probably be a much better example *thumb up*


     
    Last edited: Feb 20, 2020
    dancom likes this.
  5. Justin Zimmerlee

    Justin Zimmerlee New Member

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    I got a guy from VANCOUVER to build me a burner and plumb it
     
  6. Griff

    Griff Active Member

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    Wow that escalated fast lol, coffee can forge to having a guy build one! I would have just suggested a single burner for $200 On eBay.

    Looking forward to seeing some of your work Justin, good luck *thumb up* :beer:
     
  7. Justin Zimmerlee

    Justin Zimmerlee New Member

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    It was only 60 plus shipping for the burner the weed killer I was going to get was more than that and I just happened to see the guy had forges and burners on a buy and sell group on Facebook
     
  8. dancom

    dancom Dust Maker Best Shop Tool

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    I think Justin is referring the burner itself being made in Vancouver.

    The reason I asked about the burner was, given enough BTUs just about anything could be a heat treat forge. Even horribly inefficient forges will work for heat treating given you throw piles of heat in there. Not really good fuel economy. The build aim should be to super-insulate and make it as small as practical for your intended use.

    @Griff mentioned the two brick forge, which I also am a fan of for small work. K23/K26 insulated fire brick forges might only need a swirl-tip propane torch as those bricks have incredible insulating capacity. 2" of ceramic wool will also work very well. Larger kitty litter forges are going to be less efficient at holding heat; even more so with large openings. The more you can reduce the heat loss the better. Keep openings as small as necessary, apply refractory coatings, cover openings with blocking bricks to hold the heat in etc.

    What I hate to see is this:
    [​IMG]

    The design has just about everything wrong.
    • Only 1" of ceramic wool - should be 2" minimum
    • Huge opening - just dumping heat into the room.
    • Poor interior shape with right angles - curved interior helps direct heat towards the center of the chamber
    • Top-down burner position - no swirl action. Can you say hot spot?
    • Inefficient burner design - non laminar gas flow into the jet. Should be as straight as possible.
    All these things add up. Meh, I guess it's ok if you want to plow through lots of propane. LOL

    Good luck Justin with your project. We like pictures, so be sure to let us know how it's going.

    Dan
     
  9. Justin Zimmerlee

    Justin Zimmerlee New Member

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    When I make my opening would it be better to make it a half circle opening or just make it round or use a piece of 4x4to form it?
     
  10. dancom

    dancom Dust Maker Best Shop Tool

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    I would make it round with a can or pipe as a form. The curved interior will help with flame swirl and assist in allowing the heat to radiate back towards the centre of the forge. Then lay some sacrificial "hard" firebrick in the bottom, especially if you are going to use Borax. The idea is to make the openings only as large as you absolutely need to make them. Or make a shelf outside the opening where you can park a firebrick or two to partially close off the opening to save fuel and increase temps inside.
     

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