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The Artful Bodger's furnace book
- Thread starter mjonkman
- Start date
- Joined
- Nov 9, 2013
- Messages
- 791
master53yoda , what kind of lining do you use inside your direct pour furnace? What are the advantages and disadvantages of a direct pour furnace? I'm thinking of using waste oil as a fuel (free fuel is a good thing), and was wondering if it was a good match for this type of design. Thanks for your thoughts,
GG
GG
- Joined
- Jan 15, 2013
- Messages
- 171
Both furnaces start with a 1" koawool, my crucible furnace just has a ceramic hardface that i replace as needed. The tilting furnace i covered the kaowool with a 3/8 mesh stainless wire and the a 50 50 mix of 100 grit silica sand and the ceramic slip. once that had dried i gave it a thin covering of pure ceramic slip and then fired it to about 2300 to vitrify the surface. Bear in mind that niether of my furnaces are intended to do cast iron. the top end is brass. The purpose of the tiliting furnace was to melt down raw scrap aluminum, I put the scrap in as large as it can handle, about 8" square by 15" long is what I aim at for size, The dross floats on top of the aluminum and heavier metals like iron sink to the bottom, I don't let anything big stay in the pour but i don't fight broken off bolts etc. as the metal goes crumbly I pull out any thing big like bearings or cylinder sleaves and then let it melt. When i pour the aluminum it pours out from under the dross and leaves the heavey on the bottom. I then put it into the crucible furnace to flux and degass.
The only draw back that i could see with the type furnace that i'm running the burner needs to be able to run clean in open air and still run ok when the furnace is closed up. I would thing that a Delvan siphon type burner should work ok you may need to keep a constant ignition source to prevent flame out when your first starting the breakdown processs because the top is normally off the furnace untill it gets broken down. My gas burners don't have a flame out issue but they will flame out if the scrap has oil etc on it because of insufficient air. If I start getting smoke i cut back the gas so the air is excess and the oil etc. can burn clean once the other fuels are burnt i open the gas back up and it normally relights. That process would probbaly not be as easy firing oil. The only thing i have found that won't burn clean is even small amounts of rubber that is used for a vibration isolators. I strip every bit of that off of the casting because of the not burning clean.
bear in mind these furnaces were designed for aluminum and temps typically even when melting the aluminum our of the dross at the end of a run don't get mucj over 1850 to 1900.
good luck
art B
The only draw back that i could see with the type furnace that i'm running the burner needs to be able to run clean in open air and still run ok when the furnace is closed up. I would thing that a Delvan siphon type burner should work ok you may need to keep a constant ignition source to prevent flame out when your first starting the breakdown processs because the top is normally off the furnace untill it gets broken down. My gas burners don't have a flame out issue but they will flame out if the scrap has oil etc on it because of insufficient air. If I start getting smoke i cut back the gas so the air is excess and the oil etc. can burn clean once the other fuels are burnt i open the gas back up and it normally relights. That process would probbaly not be as easy firing oil. The only thing i have found that won't burn clean is even small amounts of rubber that is used for a vibration isolators. I strip every bit of that off of the casting because of the not burning clean.
bear in mind these furnaces were designed for aluminum and temps typically even when melting the aluminum our of the dross at the end of a run don't get mucj over 1850 to 1900.
good luck
art B
- Joined
- Jul 26, 2011
- Messages
- 4,142
Aluminum may melt at a lower temp,but it also transfers heat quicker than iron. Either metal is more than hot enough to vaporize your flesh,don't forget. Wear shoes you can kick off as suggested. NEVER wear tall boots that metal can get down into. You will have very severe burns before you can get one off.