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  1. #46
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    Apr 2008
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    Canberra
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    Yeah, for a fair while from what I understand. Especially when casting aluminium. You need to do some "mulling" between uses (mixing/fluffing of the sand), but as its oil based it doesnt dry out like green sand does which not only needs to be mulled but also needs to be brought back up to the correct moisture level.

    I think the idea is that you throw away the charred bits of sand from around the pattern, and then keep the rest...depending on how many melts you do you eventually throw out all your sand.

  2. #47
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    Lindfield N.S.W.
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    BTW ISTR reading somewhere (old Model Engineer perhaps) that the best charcoal for forges and furnaces is/was made from plum stones.

    Sounds like someone needs to find out what a jam-maker does with its plum stones and get a few sacks...
    Cheers

    Jeremy
    If it were done when 'tis done, then 'twere well it were done quickly

  3. #48
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    May 2009
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    Northern NSW OZ
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    I had only just gotten a hold of some home foundry books from the Workshop Practice Series, as i have a bit of scrap Aluminium that i would like to turn into shapes suitable for turning and milling also.

    Will be interesting to find others on the forum with likewise interests, and maybe other info on making a home melting furnace as well.

    Tez2

  4. #49
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    Jun 2008
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    Victoria, Australia
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    Hi Tez,

    I have just completed a propane foundry, we did our first bronze pour last night, melted 1kg of bronze in about 7 minutes. exciting stuff.., just ingots at this stage. Haven't actually cast anything useful yet. I was looking forward to doing some more today, but the rain has settled in, so I'm making a better crucible pouring setup and a set of lifting tongs.

    As this thread is about charcoal powered foundries, I will start a new thread in a few days time, and give a bit of a description of the propane burner and the furnace construction.

    Regards
    Ray

  5. #50
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    Apr 2008
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    Canberra
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    RayG do you know what sort of fuel consumption you get out of your propane burner?

  6. #51
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    Jun 2008
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    Victoria, Australia
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    Quote Originally Posted by 19brendan81 View Post
    RayG do you know what sort of fuel consumption you get out of your propane burner?
    Hi Brendan,

    Still haven't measured it. I am planning on commandeering the bathroom scales to sacrifice in the interests of the cause. So I should be able to get an idea of Kg/hr of propane at various pressure settings.

    I did a bit of research and here a few numbers of interest.

    1. It takes 12.3 cubic meters of air per Kg of propane for complete combustion.
    2. Each Kg of propane produces 12.9 KiloWatt Hours of power.

    From the amount of propane being burnt, you can calculate the total power input to the furnace, and how much air is required (if using a blower).

    I suspect that I'm using 2-3 Kg/hour (don't really know yet) so probably about 25-40 KW of heating..

    Regards
    Ray

  7. #52
    Join Date
    Aug 2003
    Location
    Pambula
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    58
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    987

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    I'd like to see someone have a go at making one of these:

    http://www.green-trust.org/2000/biof...on/default.htm

    You can burn waste cooking oil.
    "I don't practice what I preach because I'm not the kind of person I'm preaching to."

  8. #53
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    Apr 2008
    Location
    Canberra
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    805

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    2 -3 kg per hour isnt bad. If your alloy melt only took 7 mins you would get a lot of melts out a 9kg cylinder.

    I tried making a waste oil burner but didnt get it right. I gave up because of the smell it produces, it was pretty ordinary and you could smell it down the street. I wouldnt get away with it long until a neighbor complained.

    i got my petrobond sand last night, its so awesome. I think ill finally be able to get the casting results I have been hoping for.

  9. #54
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    Jan 2008
    Location
    qld
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    Ray,

    Are you using a regulator for your propane burner? also is it a 1 inch or 3/4 inch burner?

    Regards,

    James

    Quote Originally Posted by RayG View Post
    Hi Brendan,

    Still haven't measured it. I am planning on commandeering the bathroom scales to sacrifice in the interests of the cause. So I should be able to get an idea of Kg/hr of propane at various pressure settings.

    I did a bit of research and here a few numbers of interest.

    1. It takes 12.3 cubic meters of air per Kg of propane for complete combustion.
    2. Each Kg of propane produces 12.9 KiloWatt Hours of power.

    From the amount of propane being burnt, you can calculate the total power input to the furnace, and how much air is required (if using a blower).

    I suspect that I'm using 2-3 Kg/hour (don't really know yet) so probably about 25-40 KW of heating..

    Regards
    Ray

  10. #55
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    Jun 2008
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    Victoria, Australia
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    Quote Originally Posted by yjnb View Post
    Ray,

    Are you using a regulator for your propane burner? also is it a 1 inch or 3/4 inch burner?

    Regards,

    James

    Hi James,





    The burner is 1 1/4, and the regulator is a BOC 6000 LPG regulator

    The sheet metal flare burnt out, and the ceramic flare cracked when dropped, before it even got into the furnace, so I've got to cast a new refractory flare sometime soon.

    The bathroom scales were a dead loss for measuring the propane consumption, they are the digital type that automatically turn off, when you try and read the weight

    Regards
    Ray

  11. #56
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    Jan 2008
    Location
    qld
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    Wow,

    That's quite a burner. Would you mind posting where you got the plans, and how you constructed it? Perhaps this would be better put in your new thread.

    I have a 3/4 inch Reil burner and a 3/4 inch Frosty T burner (you'll know it if you have been on Iforgeiron). The Frosty burner is the better of the two. Both are made from steel plumbing pipe and work OK. They don't melt 1 kg of brass in 7 minutes though, more like 15 minutes.

    I have cast a couple of knobs/ screws for wooden planes and one lever for a record lever cap. It's easy to get close enough to shape and finish with filing/ sanding, but hard to get a decent finish off the bat.

    Looking good, can't wait to see some casting

    Regards,

    James

  12. #57
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    May 2009
    Location
    Northern NSW OZ
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    20

    Post Propane Gas Backyard Foundry

    Quote Originally Posted by RayG View Post
    Hi Tez,

    I have just completed a propane foundry, we did our first bronze pour last night, ........................ I will start a new thread in a few days time, and give a bit of a description of the propane burner and the furnace construction.

    Regards
    Ray

    Would love to see what you have, both the foundry and how the burner goes.

    I have started the casing for my foundry, using old LPG bottles. I filled them with water after venting them for some time and blowing them out fully with compressed air, emptied the water out and cut the top off with an angle grinder cut-off wheel.

    ******************

    For safety sake, all remnants of gas must be removed from the cylinders before cutting them, the Gas/Air mixed with grinder sparks wouldnt make for a happy day at all.
    NEVER attempt this with any cylinder that has even a hint of gas in it...........


    ******************

    One thing i did notice was that the insides of the bottles after cutting them up had a whole heap of rusty crud inside, and the inside walls had a rust coating on them which had to be removed with a wire brush on the angle grinder.

    The top of the cylinder has now had a 100mm hole cut in it and is ready for drilling to put in small bolts and securing wire to hold the castable insulation in place.

    The bottom section is being prepared at the moment to have a suitable hole drilled in the perimeter for a burner, which i have yet to make up, and will probably be on the basis of using a 200mm length of 1" od black water pipe.

    For the refractory material i am considering using the mix i had come across that utilises grog and fireclay to see how that stands up.

    Any suggestions would be most welcome as regards construction in any of its forms...

    Tez2

  13. #58
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    Quote Originally Posted by Tez2 View Post
    Would love to see what you have, both the foundry and how the burner goes.
    <snip>
    For the refractory material i am considering using the mix i had come across that utilises grog and fireclay to see how that stands up.

    Any suggestions would be most welcome as regards construction in any of its forms...

    Tez2
    Hi Tez2,

    I would use a ceramic blanket lining on the inside of the refractory mix, the problem with (just) using a solid refractory material is that it is a poor insulator when compared to the Kaowool (or in my case Cerachem) what this means is that you will be losing a lot of heat just heating up the refractory and will require more heat input to get up to temperature.

    Then, the ceramic blanket needs to be protected with a coating, I used ITC-100 which is an infra-red reflective coating that further acts to keep the heat in.

    Hope this makes sense.

    Regards
    Ray

  14. #59
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    Canberra
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    Ray G your approach seems valid but would it not be overkill for a home foundry? I built my foundry with plain portland cement, and it melts aluminium using charcoal as fuel in 5 - 7 mins, has done 10 or 12 melts and is still going strong. The portland has no insulation in it whatsoever, no perlite etc. The outside of my foundry remains cool to touch after two or three melts in succession.

    I guess what you choose to use Tez will depend on how often you plan on using your foundry. If you break it out once every couple of months like me, you can have one ready to go for about $20. If you want to use it every day you might want to consider Rays approach.

  15. #60
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    Hi Brendan, Tez,

    Yes, the extra insulation just lets you get to higher temperatures, so you are correct, it is probably overkill for Aluminium (~650 C) casting.

    With the setup I have built it is my intention is to have the capability to do cast iron (~1300 C) and of course bronze (1000 C). Haven't actually tried to melt any cast Iron as yet, the silicon carbide crucibles are not rated that high, but I have a clay graphite crucible that will do the job.

    Having too much fun with bronze and aluminium at the moment..

    So, whether it's worth the extra expense is dependant on exactly what you are wanting to do.

    Regards
    Ray

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