# Propane Furnace



## kadriver (Nov 23, 2019)

Does anyone have any experience with one of these?

I'll be melting cement silver and pouring into water to make granules for my silver cell.

https://www.ebay.com/itm/4-Kg-Propane-Melting-Furnace-Metal-Gold-Copper-Silver-Aluminium-Brass-Bronze/183681837563?hash=item2ac44a69fb:g:dmAAAOSwXqJdhMM0

Thank you


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## FrugalRefiner (Nov 23, 2019)

I'd say you can build your own for a lot less money.

If you're melting it, why not pour anode bars instead of shot? I'm not criticizing. I'm asking if you have a reason that shot is better than bars.

Dave


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## kadriver (Nov 23, 2019)

I used to make bars. Then I started making shot instead. Someone on the forum said that shot presents a greater surface area. Plus making bars for my small setup takes longer than pouring shot.


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## Slochteren (Nov 24, 2019)

FrugalRefiner said:


> I'd say you can build your own for a lot less money.
> 
> If you're melting it, why not pour anode bars instead of shot? I'm not criticizing. I'm asking if you have a reason that shot is better than bars.
> 
> Dave


I use one from devil forge, works good and fast, I use a #4 crucible in which fits almost 1 kilo cemented silver, it melts in less then 15 mins

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## Slochteren (Nov 24, 2019)

Just melted 1,384 kilo cemented silver in a A6 crucible, it took 9,15 min. to melt from a cold furnace






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## Johnny5 (Nov 24, 2019)

I've made multiple furnaces using ceramic fiber insulation. It weighs very little, can be easily shaped, durable, and some models can withstand around 3000F deg. 
I built most of my furnaces using a galvanised trash can. I usually used a roof torch from Harbor Freight ($20) for my heat source, and a small propane tank for fuel.
1 roll of insulation, can make about 3 large furnaces (see pics) , or many more smaller ones. 
This insulation is incredibly efficient, and takes almost no time to get to temp. 
I used to buy it by the roll at Grainger for about $100 shipped to the store, but I found a man that bought a storage unit full of it, and was getting rid of it cheap, so I stocked up.
I have used it many times for incinerating BGA's, stripping ram chips from memory, removing lids from CPU's, and I've melted thousands of pounds of aluminum.

.


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## rickbb (Nov 26, 2019)

I made one similar to that trash can, but I wrapped the ceramic wool with hardware cloth. 

I added an old heat gun and use it as a blower, makes it even hotter in there.


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## Johnny5 (Nov 26, 2019)

rickbb said:


> I made one similar to that trash can, but I wrapped the ceramic wool with hardware cloth.
> 
> I added an old heat gun and use it as a blower, makes it even hotter in there.



When I first started melting aluminum, I used stainless steel crucibles, melted through quite a few of them quickly. The last thing I wanted was more heat. The output on those torches is adjustable, so I ended up having to turn it down to where there was barely a flame. The absorption time is a little long when using a 200+lb crucible, but it's worth it. The steel crucibles I used for aluminum held about 80lbs of aluminum, and could get to 1500+ degrees in less than an hour.


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## kadriver (Nov 28, 2019)

Thank you for your replies. Good useful information.

kadriver


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## rickzeien (Nov 28, 2019)

I like this guys design. If I was building a small kiln it would be like this one. If I didn't build one I would try one of his. (I am not affiliated in any way)

https://youtu.be/oTmeX4ZYpME

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## snoman701 (Nov 28, 2019)

Much safer than kaowool. 

Kaowool is great stuff, but is often misused. 


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## butcher (Nov 28, 2019)

I do not like the idea of using a galvanized can for the shell of a furnace.


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## Johnny5 (Nov 28, 2019)

butcher said:


> I do not like the idea of using a galvanized can for the shell of a furnace.



It really doesn't get that hot. However if it's a concern, I made one out of a 55 gallon metal drum cut in half, and it also worked like a charm. I continued using the trash cans because they already had handles and lids, and were very inexpensive.


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## snoman701 (Nov 28, 2019)

butcher said:


> I do not like the idea of using a galvanized can for the shell of a furnace.


Very common....google raku kiln. 




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## butcher (Nov 28, 2019)

It may be common, and convenient.

I personally would not use a zinc coating in the furnace shell construction, fume fever is like the common cold, and feels like a terrible flue.

True the users may have all kinds of dangerous gases in a melt in one of these homemade furnaces including zinc if he is making brass...


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## Lou (Nov 28, 2019)

Johnny5 said:


> I've made multiple furnaces using ceramic fiber insulation. It weighs very little, can be easily shaped, durable, and some models can withstand around 3000F deg.
> I built most of my furnaces using a galvanised trash can. I usually used a roof torch from Harbor Freight ($20) for my heat source, and a small propane tank for fuel.
> 1 roll of insulation, can make about 3 large furnaces (see pics) , or many more smaller ones.
> This insulation is incredibly efficient, and takes almost no time to get to temp.
> ...



I built one just like this!! I loved that furnace. I cast the bottom out of Portland and pearlite. Similar story...friend’s girlfriend’s dad had a bunch and we got several boxes worth.

I never had the furnace lose the galvanizing except right at the tuyere. The lid we used was an old kiln lid. We rebuilt and relined that furnace many times. Melted aluminum, brass, bronze, magnesium, silver and even cast iron in it.


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