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Foundry Furnace - Final

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Wed, 04/03/2013 - 17:59 — Jake von Slatt
 

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.

Articles:
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Comments

sten333 - Tue, 02/16/2010 - 03:24.

My gods man! I have poured molten aluminum, bronze, iron etc... for my sculpture and jewelery... that is one compact device!

how many lbs. can that crucible hold? What is the sustainable BTUs you can crank out of that thing? What are you going to do with those ingots you are so nicely stacking together?

Do you have a cost analysis for material + fuel vs. product?

I would love to make one myself.... only bigger.

Look for my e-mail

Jake von Slatt - Tue, 02/16/2010 - 14:02.

The crucible holds 11 pounds of aluminum, I've no idea what the heat input is but I suppose you could calculate it from the oil consumption.

The refractory cement cost me about $250, but that was the only real expense, everything else came from the dump or was free. The fuel is the peanut oil left over from frying our Thanksgiving turkey and I have several gallons of waste motor oil to burn as well.

ZeratoulX - Tue, 03/30/2010 - 22:48.

I was wondering two things;
1. How efficent/clean/safe would it be to run it on motor oil (leftovers from oil changes at fairly normal intervals assumed)
2. It may be something one has to choose for ones self but does aluminum really fit the steampunk aesthetic? I was considering doing a project in aluminum (wonderful metal, cheap, light, easy to use, durable, etc.) and presenting it to the internet until i realized a polished aluminum body would leave it looking rather odd mixed in with copper, brass and iron. maybe im just taking this a little too literal and concentrate on the making aspect of the project as a whole? your opinion would be appreciated.
ITT: should one sacrifice aesthetic for plausibility?

Jake von Slatt - Thu, 04/01/2010 - 10:44.

1. Motor oil is reported to work even better than veggie oil, burning cleanly with little or no smoke. Still, I'll be careful to stay downwind when I try it.

2. Aluminum was actually used in Jewelry in the 19th century before a method to smelt large quantities was developed. I say go for it! and it is does come out steampunk enough for you just call it dieselpunk!

steamdon - Tue, 02/16/2010 - 07:17.

I just love the lighting. That is true steampunk. Nice one Jake.

zahal - Tue, 02/16/2010 - 09:33.

So the Al goes into the fire extinguisher bottom, and this gets placed in the furnce. when you retrive it, what do you pour the molten metal into. i.e what is your mold?

Looks good!

Jake von Slatt - Tue, 02/16/2010 - 13:58.

They're just lengths of angle iron welded at the ends. Each is about a pound of material and the crucible holds about 11 pounds of molten aluminum.

Datamancer - Tue, 02/16/2010 - 12:42.

Hot damn! IT LIVES!!! Congratulations!

JGN - Tue, 02/16/2010 - 13:35.

Nice job, Jake. The light pole is sick. Now you need to paint it all up and add a few brass accents; maybe a gauge or two, too (voltage, vacuum [draft]).

Jake von Slatt - Tue, 02/16/2010 - 13:55.

The furnace is actually acquiring a nice patina of soot so I'll leave that alone. The waste oil tank needs a paint job though.

FriarGreg - Tue, 02/16/2010 - 13:41.

1) what would you have to do with the slag if you continue to use the foundry? It can't be worth anything and too dangerous to just bury.

2) are you going to sell the bars for scrap or use them in future forging projects?

3) Would copper be a suitable material to use in your foundry?

I have so many other questions that I just can't put to words right now... Keep up the awesome work!!!

Jake von Slatt - Tue, 02/16/2010 - 13:54.
  1. The slag is not really dangerous, it's pretty inert stuff.  I have heard of it being re-used in home mix refractories so it might have some utility.
  2. I'm making ingots to have clean and consistent metal for future melts.
  3. I do expect to be able to melt copper and brass, but they are much harder to work with.

Cwhaley - Wed, 02/17/2010 - 01:56.

With the foundry at optimal temperature how hot does the handle get?

Jake von Slatt - Thu, 02/18/2010 - 12:32.

The outside of the furnace really doesn't get hot at all, the insulating refractory is very effective.

lepton - Wed, 02/17/2010 - 09:48.

Yikes! - what is the source of the flames out the bottom - under the crucible?
Is there enough air pressure to force the combustion gasses through the plinth channels and out the spill hole?

Maybe add a shield of some sort to protect the tires? Flames + inflated rubber might get your fire extinguisher used more often than you prefer. Maybe a couple firebricks moved into position before firing as deflectors would be an easy. low tech solution.

Also - any particular reason for abandoning the injector/gasoline setup for initial startup?
The PWM controlled injector is pretty slick - although your current setup is probably more reliable. Having an electronics problem put your casting session on hold would be frustrating.

Thanks for the great writeup - it's motivating me to get off my duff and get mine furnace put together.

Jake von Slatt - Thu, 02/18/2010 - 12:37.

There is a blast shield under the furnace so the tires are quiet safe. The main problem with the gasoline startup was that injector was too slow to control effectively. Four injectors working in sequence would probably have worked really well, but things were getting complicated.  I did learn a lot though and that was the real point.

Chris L - Wed, 02/24/2010 - 16:54.

Hi Jake, I'm sure I'm telling you something you already know, but for the benefit of less clueful readers:

Never EVER cut steel and alumium with the same high-speed tools. In fact don't even do it in the same area. Ferrous oxide (know as rust!) + clean aluminium = thermite. It's a violently exothermic reaction, and if you're very lucky it'll only remove your eyebrows and fingers. Lots of guys restoring old cars have been zapped by this.

I assume you put a clean blade on that angle-grinder before you cut the wheels...

Jake von Slatt - Sat, 02/27/2010 - 09:44.

Abrasives really suck at cutting aluminum, I used the circular saw with a carbide cross cut blade--it cuts like butter. I pay very close attention to the kick-back path and, as Mr. Miyagi says: "Don't be there." But be warned, hand-held free-form circular saw cutting of aluminum is not a safe operation and probably would not be allowed in any industrial setting. Try at your own risk only .  Do as I say and you'll be fine, do as I do and you are likely to be injured.

I was trying the cut off wheel on the steel belted tire, but the rubber caused too much friction. I have yet to find a way to effectively cut steel belted radials and I would like to because they are made of such awesome tough stuff.

thebiggreen - Mon, 04/05/2010 - 11:59.

I am impressed by the creativity of your build here, and I am building one of my own, with a few differences in design hoping for a slight improvement in functionality and durability... Bed frames, snowblowers, water tanks and lamp parts... very resourceful.. Have you made an attempt at making brass yet?

Jake von Slatt - Mon, 04/05/2010 - 12:22.

Not yet, I need to improve the blower performance, the blades are stalling with the lid closed.

thebiggreen - Tue, 04/06/2010 - 00:38.

I have some knowledge on the subject as my grandfather builds "Biomass" fuel burning furnaces... The construction material you've used to build the fan seems to limit it's power... likely the blades are flexing. My drafting skills are laffable at best so I will refrain from posting an image, but seems like a top vent would very much help with airflow inside the furnace... a rheostat to adjust fan speed and maybe a closeable outlet/exhaust pipe in the lid in the opposite direction of the burner inlet?... Create a spiral of fire around the crucible, and may stop flareups at the bottom... anyways these are just the ideas I am including in my drafts... Anyways these are just Ideas. Let me know if I'm making any sense, lol. (It'll help to keep me from building an oversized paperweight)

**Side note** US pennies made after 1982 are primarily made of zinc plated with copper... just found out.

kabyzdoh - Thu, 03/01/2012 - 14:53.

Hi!

Occasionally I'm searching some ceramics plates with holes and I see it here...
If you want you can use it for some grate experiments to do 2 different burners, radiant burner and
silent burner...
google.com for radiant burner
http://www.joppaglass.com/ for ceramics heads (glassmakers use burners with ceramics)...

all the best
kabyzdoh

PDCarden - Tue, 03/13/2012 - 19:54.

I was just thinking that you wouldn't need to go to far from your furnace to make a steam generator. Abner Doble put the burner towards the top of the generator and the exhaust near the bottom, getting maximum use of the heat. Of course it was a mono tube boiler. If your interested drop me an E-mail and I'll send any info and or sites to you.
p_carden@hotmail.com

Cathy Garrett - Sat, 04/06/2013 - 11:49.

Do you have any tips for analysis of the resulting ingots? I'd love to be able to make high speed machine parts out of aluminum, but need something more 7075 than 6065. How would I tell the percentages of alloying elements I have in a given ingot?

For some reason, I can't shake the idea that the brass door knob the WVO is being drizzled on is being rotated at high speed. Please disillusion me of this delusion.

If the crucible bar lugs are at 90° and 270°, why would you put the pouring spouts at 0° and 180°, which means the user needs to essentially be directly behind or even right over the bar to pour, as opposed to something like 60° and 240°, or even 67.5°, 112.5°, 247.6° and 292.5°, for ambidextrous use, which would make it easier to make the pour while standing to the side of the moulds?

Seemed you had a large amound of slag to contend with. Would sandblasting the feed stock before melting help at all? How about welding up a slag basket to fit tightly inside the crucible? Would that make it easier to strain out the slag, leaving just the aluminum and other desireable alloying metals, allowing you to go from foundry to mould more quickly and easily? What proportion of the desired aluminum is removed in the slag removal process?

If you were to heat-soak your moulds, what kind of ideas do you have for post-apocalyptic engineering to address that problem at this time?

If you were to hot-forge the resulting aluminum parts prior to (CNC) milling, what kind of ideas do you have for post-apocalyptic engineering to address that problem at this time?

Zendo Deb - Wed, 05/15/2013 - 22:34.

High top work boots. (The video it looks like sneakers, or something)

A respirator at least. Better pipe in air from somewhere. A fan blowing fumes away. (Metal poisoning is a nasty business...)

I could go on...

Jake von Slatt - Thu, 05/16/2013 - 10:14.

Actually the most dangerous thing here is the free-style cutting of alloy wheels with carpentry tools! ;-)