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Dual Fuel Metal Melting Furnace

Dual Fuel Metal Melting Furnace
I got such a great response from the Easy Dual Fuel Furnace Burner that it only made sense to follow it up with the rest of the furnace.

This furnace will be able to handle melting aluminum and bronze with no trouble. In theory it should be able to melt iron too but that's probably pushing it.

I've been using my furnace for a couple years now and it has worked out quite well. My design is based on information I picked up from the backyard metalcasting forum. It's a great resource and community. There are a bunch of furnace builds there exploring a variety of ideas. I recommend checking it out. I'd also read this comprehensive guide for a general overview of metal casting and furnace design.
 
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Step 1General Plan

The basic concept is that we are making an insulated container that can withstand temperatures of up to 2600 degrees. The dimensions don't need to be precise but you will have better results if you stick with the general program. I wanted a furnace that would let me cast a decent amount of metal, about 5 lbs aluminum.  It needs to be sturdy but as inexpensive as possible to make and run.

The furnace is really simple. It's just a metal container with a lid, a drain and a hole for the burner. It is filled with high temperature insulation to retain the heat and a sturdy inner lining (hot face) to withstand the flame from the burner.

I based my design around a small metal barrel that I got from a salvage place. The sheet metal was thick enough to weld to (pretty much) and not galvanized. The zinc coating on galvanazed metal containers will burn and make a noxious smoke so don't use it. Otherwise any metal container should make a serviceable shell for the furnace. I used bits of pipe and angle iron from my scrap pile for the rest of the metal parts.

I made my own insulation because it was substantially cheaper than buying commercial insulation and I just wanted to try it. I did buy a bag of high temperature refractory cement for the hot face.

The shell is filled with insulation leaving an airspace of roughly 2" on all sides between the crucible and the inside of the furnace.
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16 comments
Jan 5, 2012. 11:10 AMstatic says:
Great instructable, saved it for future reference. On the 100 W. light bulbs, LOL. I'm certain that 100 W. incandescent bulbs that meet the energy efficiency standards are available
Dec 7, 2011. 8:33 PMhag says:
I was just wondering what you used for a burner. The only thing that comes to my mind is a propane blow torch, but I doubt that gets hot enough.
Jan 1, 2012. 3:46 AMAce193 says:
This is a great 'ible. Your eye for detail in writing this one made it very useful. Keep up the good work!
Dec 19, 2011. 11:41 PMlewster says:
Looks awesome, great 'ible
Dec 2, 2011. 6:34 PMpj63 says:
What a Great Instructable....I've been waiting for a while for this to come up...I have Bricks,Fire Cement and a 25kg bag of Fire Clay to try to build a Smelting/Foundry in my Garden..I needed some final information and your Instr was Brilliant..Thanks and well done very informative...
Dec 1, 2011. 8:25 AMrobotjim says:
thanks for the tips, been wanting to try melting
and casting metal for ages...this looks easy enough
I've got no excuse not to !
Dec 1, 2011. 8:17 AMwasabi237 says:
Gold melts at around 1800. Whoo Hoo!
Dec 1, 2011. 7:33 AMkenwork says:
Loved this instructable on creating a metal melting furnace! Thank you!

BTW, your website address is incomplete at the end of the instructable, it is missing the .com.

Here is the complete link for people that want to see Mike and Molly's house :)
http://mikeandmollyshouse.com/
Nov 29, 2011. 3:31 PMPS118 says:
Do you think it would help with the cracking to dry the insulation before pouring the liner?
Nov 28, 2011. 9:11 PMdrewgrey says:
Awesome, looks like fun!
Nov 28, 2011. 1:29 PMsoul_eater says:
it looks Great , Im going to make plans to build this one
Nov 28, 2011. 11:06 AMrimar2000 says:
GENIAL, thanks for sharing.

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Author:spike3579(Mike and Molly's House)
I like to make stuff, all kinds of stuff. Everything from building a guest house out of household trash to how to make holiday baby hands. I'm posting projects here at Instructables as well as my bl...
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