Pouring 1200° Tea: Foundry In A Fire Extinguisher

Let’s face it — the design of most home foundries leaves something to be desired. Most foundries are great at melting metal, but when it comes to pouring the melt, awkward handling can easily lead to horrific results. That’s why we appreciate the thought that went into this electric melting pot foundry.

Sure, electric foundries lack some of the sex-appeal of gas- or even charcoal-fueled foundries, but by eschewing the open flames and shooting sparks, [Turbo Conquering Mega Eagle] was able to integrate the crucible into the foundry body and create what looks for all the world like a Thermos bottle for molten aluminum.

The body is a decapitated fire extinguisher, while the crucible appears to just be a length of steel pipe. An electric stove heating element is wrapped around the crucible, PID control of which is taken care of by an external controller and solid state relay. Insulated with Pearlite and provided with a handle, pours are now as safe as making a nice cup of 1200° tea.

You’ll perhaps recall that [Turbo Conquering Mega Eagle] has a thing for electric foundries, although we have to say the fit and finish of the current work far exceeds his previous quick-and-dirty build using an old electric stove.

[via r/metalworking]

29 thoughts on “Pouring 1200° Tea: Foundry In A Fire Extinguisher

    1. Just like pouring hot water from an electric kettle, your hand ends up directly above all the hot stuff being poured. Moving the handle closer to the bottom or to the sides should be a little safer.

  1. I think you meant the volcanic amorphous solid perlite not a solid phase of cast iron, pearlite.

    Obviously the element can get that high, but I wonder how this affects the lifespan? You can get some weird reactions between the refractory-element-crucible at those temps. I’m also impressed by the fact that the element didn’t crack during construction, I’ve always heard they’re not terribly robust.

    Holy NSFW, he also has a lot more faith in those grinder guards than I do.

    1. By bending them before the internal ceramic is fused. Not all elements are flexible. There are specially made ones that have not been fired so the ceramic can bend without cracking, fusing on the first firing.

      As for the thermal cycling and lifespan, these elements are designed to run in free air, at significantly lower temperatures. Your average electric oven may only get up to 800 on a clean cycle, aluminum melts above 1200. Yes the element is red hot either way, but sometimes these things make a difference. Putting a refractory cement (that might not be be meant for element contact) on top of the element may also shorten its life span.

      1. Some of the elements have some kind of compacted powder as an insulation.
        But how do you come to 1200° for the melting point of aluminium? According to Wikipedia it is 660° (933K). Or do you need to heat it so much over it’s actual melting point to be able to pour it?

        1. with so few countries actually using it it is perfectly normal that people wouldn’t even know what imperial is, my younger siblings don’t, they have never encountered it.

      1. He’s using 240 V mains power via an extender lead with a fused plug (13A) at one end and an IEC 60320 kettle type connector at the other. You would have noticed it if there was a short circuit at the crucible.
        He is working in his own back yard, if he wants to work dangerously it’s his business. He made a working electrically heated crucible and a decent video, I couldn’t do either let alone both together.

    1. I have a 4mm thick piece of steel tubing I’ve been using to pour aluminum for 20 years, and if anything it’s gotten more rusty inside over the years, rather than being etched away. Every now and then I have to reweld a bit where I welded the bottom plate onto the tubing, but any loss of bulk metal is so small I can’t measure it.

  2. @4:16 pack of Rizla rolling papers with a corner of the cardboard torn off.
    Last time I saw someone with a pack in the same condition, and asked him about it, he couldn’t stop laughing.

    that machine shop desperately needs some cleaning up though, all that poor machinery. Probably a safety hazard too.

    1. A case of sour grapes for you?

      The guy is a doer and deserves all the admiration is due as an “achiever”.

      Nit picking achieves nothing. Written or spoken. Achieves nothing

      PS: just in case:
      My use of “Sour grapes” refer to:
      Pretending that one doesn’t want something, because one does not or cannot have it, also known as being a “Sour Grapes Mary”.

      By any chance, are you an Australian Licensed Electrician? They seem to have that negative, perennially chastising attitude towards doing things.

      1. That lathe is a disgrace whatever persuasion of engineer you are.

        Not knocking the make or the presentation at all, that is first class but I would be embarrassed to show that lathe to anyone.

    2. in western europe some ppl use that piece of cardboard to roll a filter for funny cigarettes, so i was implying he was busted. perhaps i should not have made that remark on this board. never the less, that shop could use some serious cleaning.

    1. Pot?
      HTTP Error 418 I’m a Teapot?

      Before pointing out apparent “unsafe practices” (your writting, not mine) it is important to point out creativity and skills. Kinda being positive and constructive rather than negative and destructive.

      As it was mentioned some time back in Hackaday: DON’T BE A TYRANT , BE A MENTOR.
      Mentors guide with the proverbial “excellent job, well done … but”
      Tyrants criticize.

    1. For occasional use when you have set everything up first because it’s kept in storage – this is way better.
      Take out the pot, load with metal, plug it in, go sort the mold, once it’s molten, you’re ready to cast.

  3. Holy crap, so that’s what a real man looks like. Welding without proper protective gear and even keeping the bare hand on the metal. I was somewhat surprise he wasn’t shocked when he forgot the ground clamp in that one scene.

  4. The temperature probe might be off because a thermocouple signal is being run over regular copper wires, and at the point where they join, they’re sensing the temperature of that junction too. The controller isn’t expecting that, and the temperature of those other junctions isn’t being figured into the calculation. (Also, it isn’t known.)

    Look up “cold junction compensation” for some better descriptions of why. Long story short, the signal has to be run over thermocouple wires and thermocouple connectors, the whole way back to the controller.

  5. As a long-time home foundry caster, I really like this. Most of the really dangerous parts of casting are in the removing of the crucible from the furnace, moving it to the mold, and starting the pour. This totally manages all of that with the exception of having your hand and body waaaaay too close to the metal as it starts to go into the mold. But it totally gets rid of dropped crucibles.
    Jewelry casting setups are sometimes built with an inductively heated crucible attached to the side of the vacuum casting setup, so once the mold has fully burnt out, you drop it in the vacuum box, turn on the vacuum, and then just invert the crucible on its pivot and it pours right in the mold. I think something similar could be done here, with a gimbal and a lever arm so you could be a meter away as the metal starts to pour.

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