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My little furnace

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  1. #1
    snapperhead started this thread.
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    My little furnace

    I wanted to see if I could get some pictures posted, this is my first attempt, lets see if I can do this.

    I wanted to share some Pics of my little furnace (this one holds a #6 crucible)






    This is the whole setup turning some scrap Aluminium into clean ingots, for future casting projects


    My crucible holder and pouring shank


    This is the basic furnace construction, just 10 hollowed out fire bricks and an angle steel cage to hold it together

    OK, I will post this and see if it worked, if it does I will add more
    Last edited by snapperhead; 07-06-2014 at 04:43 PM. Reason: getting Pic url's right
    If it wasn't for the laws of physics, I would be unstoppable.

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  3. #2
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    Nice set up. What type of fuel are you using? I was thinking about using a 5 gal metal bucket lined with kawool with a hole cut in to use a propane/oxy set up. Need to get up to 1900 degrees for what i plan on melting.
    I won't be wronged. I won't be insulted. I won't be laid a-hand on. I don't do these things to other people, and I require the same from them. John Wayne-- The Shootist

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    That worked well then, more pics .


    Furnace in action, scrap goes in the exhaust port.
    It works so well that I can melt aluminium less than a foot away from wooden wall, and it doesn't even get the wall warm.


    One safety tip is that you should not do this on a paved surface (like I am doing here), If you spill the molten metal, it will go between the pavers and explode up and out everywhere due to the moisture between them. Spraying you and the walls with molten metal. Lesson learned the hard way.


    A few ingots of Aluminium from one session.

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    snapperhead started this thread.
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    Thanks BC
    I just use LPG (propane up in your hemisphere)
    It is just a bbq bottle and regulator, connected to home made burner pieced together from scrap. The combustion air comes from a modified blower out of a clothes drier.
    It is so so simple to make, I will give details and pics if you are interested.
    I dont know whether you can get enough BTU's into your bucket setup with using Oxy/acet. Only because the tips just cant deliver the flame size needed to get up to copper based alloy temperatures.
    With my little furnace, I can have 3 kg of molten brass in around half an hour from a cold start.

    The bucket and kaowool setup is perfect, but the kaowool will deteriorate quickly if left un-sealed and pieces will break away. If you can get some sort of rigid hot face onto the kaowool, it will last a lot longer. Not needed if you are just going to use it a couple of times though.

    My large furnace is still under construction (#16 crucible) and it is just a sophisticated metal bucket, with kaowool insulation and a 15mm thick hotface (I use mine a lot and need the robust inner layer)

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    snapperhead started this thread.
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    Thanks BC
    I just use LPG (propane up in your hemisphere)
    It is just a bbq bottle and regulator, connected to home made burner pieced together from scrap. The combustion air comes from a modified blower out of a clothes drier.
    It is so so simple to make, I will give details and pics if you are interested.
    I dont know whether you can get enough BTU's into your bucket setup with using Oxy/acet. Only because the tips just cant deliver the flame size needed to get up to copper based alloy temperatures.
    With my little furnace, I can have 3 kg of molten brass in around half an hour from a cold start.

    The bucket and kaowool setup is perfect, but the kaowool will deteriorate quickly if left un-sealed and pieces will break away. If you can get some sort of rigid hot face onto the kaowool, it will last a lot longer. Not needed if you are just going to use it a couple of times though.

    My large furnace is still under construction (#16 crucible) and it is just a sophisticated metal bucket, with kaowool insulation and a 15mm thick hotface (I use mine a lot and need the robust inner layer)

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    I was thinking of using a refractory to harden the kawool so it would last longer. I would definitely like to get direction on the dryer blower set up. I would be using a lp/oxy set up. Need the oxy mix to get temps up to melt Au and Ag. Probably going to use a #6 crucible and also small melting dishes.

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    This is the burner and blower setup


    This is the fan and motor from a scrap clothes drier. I put a safety cage around the motor and use an old light switch to turn it on and off. The inlet has an adjustable face plate to adjust the flow of air into the air/fuel mixing chamber part of the burner.


    Another pic of blower unit. The steel tube just above it is the burner mixing chamber


    The scrapheap challenge burner. Air from blower goes in the top, LPG comes in from the right via the old torch handle, fuel and air are mixed in the centre chamber and huge flames exit out the left.

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    Man ... that setup is really neat. Way to go ! LPG is a nice clean burning fuel.

    For Brass: If you needed a higher burn temperature you might look into diesel. It's pretty common to find a good gun & electricals still mounted on an oil fired furnace -or- boiler that's just been taken out of service. Pull the gun and mount it on a free standing base. Adjust it in or out of your furnace opening till the fire is where you want it. You can swap out nozzles to get more or less GPH. Diesel burns cleaner than #2 fuel oil but i was reading about one gent that had adapted his to burn used motor oil.

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  13. #9
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    From my experience BC, its all about the volume of oxygen/air that counts, not the pressure of delivery.
    The squirrel cage blower delivers high volume, low pressure air, which is perfect for these kind of ghetto burners.
    I have found that the needle valves in high pressure delivery systems can be really touchy for getting your furnace atmosphere correct for the metals you are melting (lean to rich), and there is so much accurate control from such a basic setup using cage blower.

    using a refractory to seal the face of kaowool is perfect. I sieve the big chunks out of the refractory before hydrating it, which for me, makes it easier to get a smooth face on the inside (too rough and it will cause unwanted turbulence and reduce the spiral effect that is desirable)

    You can easily get AU, Ag temps using just LP and a squirrel cage blower. This bazooka of a burner can melt copper outside the furnace, which I found out the hard way when using it to anneal copper sheet for my 8' copper alembic pot still.

    If you are melting small amounts in small firing dishes, then a micro furnace and oxy/Lp torch will be perfect. but I think you will need a similar burner to mine if you intend to get a full #6, molten within a reasonable time.
    The burner and blower only cost me $20 at the most to make. Most expensive single item was the thread sealant I used to ensure the burner was gas tight. the rest was cobbled together from items I found while cashing scrap in at my local yard.

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    Thanks Scrappah, it looks a bit worn now, but when I first made it, it looked like harry potters lunchbox.

    I am making a dual burner for the big furnace, fast start up and pre-heat using LPG, then switch over to the waste oil burner when the hotface is up to temp. Lighting a waste oil burner can be a pain (from a mixture control point of view), but once the inner chamber is up to temperature, it is easy to control. I have found that the neighbours get all titchy when there is a cloud of oily smoke pouring out the exhaust, which is the case until everything is up to temp. The dual burner should eliminate this for me.
    One thing about using waste oil is its free and everyone has some of it they will gladly give you. just be sure to filter all the bugs and grit out or it will block the jets quickly, not a good thing mid melt.

  16. #11
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    more pics


    Mid build of the blower, the block on top of the burner was a ghetto gate valve that didnt work that well and was soon ditched. I found that controlling the inlet was much more accurate than controlling the outlet of the blower


    this is the gate valve that didnt work that well.


    This was testing the burner for the first time, I was using compressed air because I hadn't got the blower finished. Thats why the flame is so small and weak, just not enough volume of air to get it firing properly

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  18. #12
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    My little reil type / venturi burner

    I also made a reil type of burner, but this lillte puppy needs a high pressure LPG regulator to work properly. This little burner can drain LPG so fast that the bottle valve freezes up




    The basic essentials, reducer fitting to get the venturi effect going, mig tip in the centre to deliver the LPG, and a basic air control plate to adjust the mixture.


    all the parts ready for assembly.

    Leave this one going to long and you will melt the polar icecaps.

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  20. #13
    snapperhead started this thread.
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    The reason I got into casting was to make motorcycle parts that I just cant fabricate from standard stock.

    so I will introduce you to my 2 wheeled toys now
    Lets see how many pics I can get in one post...









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  22. #14
    snapperhead started this thread.
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    Its just a scratch, that will polish out for sure



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    Wow great info snapperhead....nice work on the bikes too.

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    Check out this set up. This is the one I am going to try to build. I hope I did this right with the linq.

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  26. #17
    snapperhead started this thread.
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    I will stop hijacking my own thread now and continue with all things foundry


    A couple of flasks and ramming tools


    the molding bench, lower tub holds clean, mulled greensand ready to go into flasks. molds are rammed on top lid and excess sand gets swept back into the tub.


    with this shot you can see the angle that the burner needs to enter at. this gives you the vortex spiral flame around the crucible. Fire the flame straight at the crucible and you will be waiting all day for it to melt the charge. Dont try and heat the crucible itself, focus the flame in the gap between the furnace wall and the crucible, get the flame spinning around the crucible and you will have molten metal quickly and efficiently.

    Thats all from me for now
    Peace out fellow scrappers

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  28. #18
    snapperhead started this thread.
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    Thats an Awesome vid BC, I have seen it over at GRF.
    It has some great info, but also a number of serious safety issues going on too.

    1) Please, if you are going to try this, invest in some thick welding gloves and a face shield. And wear them every second you are near the furnace and tools. Handling molten metal is so dangerous, and can go wrong in the blink of an eye. It can be uncomfortable wearing the safety gear around a hot furnace, but not as devastatingly painful as the damage a mistake can cause.

    2) lifting a full crucible out of a furnace with cold vise grips is courting disaster, and will eventually bite you badly. Crucibles are fragile and regularly fail, even when held correctly. there are many ways to make a set of lifting tongs, and cheaper than a pair of vise grips too. grab the entire rim of the crucible, spread the weight of it around the whole circumference, then lift it out.

    3) drilling holes through the side of a crucible will weaken it, increasing the risk of failure from thermal and physical shock. Please dont do it. take a little longer when pouring it out the rim as it was designed to do. It may not make for such a cool looking video, but it just isnt worth the risk. If some of that water had splashed up and onto the intensely hot, modified crucible, things would have gone pear shaped at light speed.

    4) seal all gas systems, please dont just poke a gas torch at a fan and expect all the gas to get drawn away. making a quick inlet manifold out of paper and sellotape would make that setup, so much safer.

    And much less critical, but needs to be mentioned is that a bent piece of steel rod or tube would have made a quick and simple way to remove and replace the furnace lid. Keeping the operators bare arms and hands well away from the heat. The thing about Kaowool is that it works so well, you can easily forget that, just a few inches away is 2000 degrees of unforgiving heat. If you get bitten by a blast of high temp exhaust when removing the lid you will cause even worse damage to yourself when you drop the lid and bring things crashing down.

    I am not trying to put anyone off, as it is the most exhilarating feeling, handling and pouring molten metal. I just want you to do it in a way that allows you a lifetime of doing it. And no one needs the indignity of both hurting themselves and throwing your hard earned precious metal away.

    Ok, I will put nana to bed now, she has had her little speech

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  30. #19
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    Lol I'm very new to all of this and well you definitely got me worried haha.


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