Foundry Furnace – Final

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UPDATE:

I have to stop saying “final iteration!”

The latest upgrade to the foundry furnace is a Babbington style burner for the waste oil. The Babbington burner atomizes the waste oil fuel before injecting it into the furnace and make for much more controllable and stable combustion.

The burner is built with scrap steel, a brass door knob, a Volkswagen oil pump, and an old DeWalt cordless drill. I’ll do a more detailed post in the near future but for now, here is an overview.

– Jake


Here’s the final iteration of my foundry furnace. I’ve re-built the burner to be fired with propane and waste oil rather than gasoline and waste oil. I built my oil injector based on plans from the wonderful folks over at Lionel Labs, it’s essentially identical to “The Brute.”  

I also added a light pole. Since I have a day job, night-time is often my only opportunity for recreation of the metal melting sort.

The burner is simply a 16″ length of 2″ black iron pipe that I made (8) 2″ cuts in with the abrasive chop-saw.  I then hammered the ends into a venturi and welded them.

The oil feed is a 3/8″ section of steel tubing inserted into the blower tube.

Since the original refractory was showing a little bit of wear I decided to coat the inside of the base with these ceramic “dominoes” I found at the dump.  I used this 2700º furnace cement to bed and coat the ceramic dominoes.

I also made a pair of refractory plinths out of bleach bottles and some pieces of pipe.

I’ll need a crucible and I’ve heard that the bottoms of old fire extinguishers make excellent crucibles.

Both the chop saw and the extinguisher came from our dump.

I fabricated a pouring bar for the crucible from parts of an exercise machine and a Yakima roof rack.

Close up of the fabricated ears.

The whole pouring stick. The weight at the far left balances everything nicely.

As usual, the most effective tool for breaking down aluminum into meltable pieces is also the most dangerous, the circular saw.

The chop saw with a carbide blade was very effective for chopping the aluminum pieces down into smaller chunks.

Let’s melt some metal:

I found that I got the best results when the lid of the furnace was propped open a bit. This leads me to believe that the fan is stalling under high back pressure and I need to tweak the blower design a bit to so that it develops sufficient head against the restricted furnace body.

The crucible holds about 11 pounds of molten metal and takes about 10 minutes to melt.

Close up of the melting wheel parts.

The furnace cement and ceramic dominoes held up well to the oil and high temperature test.

Here’s the result of 2 hours, 2 alloy wheels and 3 gallons of waste peanut oil: 40 pounds of high-grade cast aluminum alloy.

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