Charcoal Foundry

[John Evans]

Recently, I completed the first successful casting in the “Charcoal Foundry”. As the name implies, the energy source for burnout and bronze melting is firewood and home made charcoal.

Two chicken wire reinforced solid investments, each weighing 75 kilos, were burned out over a wood fired stove in 22 hours. The burnout kiln was an insulated 45-gallon oil drum.

50 kilos of silicon bronze were brought to pour temperature, (1070 degrees C) in 2.5 hours in a homemade melt furnace. Dry birch firewood was burned during the first 1.5 hours and charcoal during the last hour. Finger print quality castings were achieved.

I was motivated to build this foundry because I am located, in Newfoundland, far from the services of a commercial lost wax foundry. I believe that a sculptor, working in bronze, should be involved in all the creative steps leading to the completion of his work. A sculptor with her own foundry can augment his income by casting other peoples work. The Charcoal Foundry was mostly built from recycled material and about $1,000 for a crucible and refractories.

I will provide more details if anyone is interested.

[clifton]

Hi John,

I would be quite interested in the details of how you set up the burner for this home made foundry.

Clifton
___________

[Landseer]

There's all kinds of google results for backyard foundry setups, including directions and lists of parts, photos etc. I'd be a lot more inclined to go with propane than all the work and additional distractions of firing with wood and charcoal and having to mess with that.
From the photos and descriptions of the burners, gas burners are little more than a piece of pipe with an inserted smaller pipe for a jet, not much to them;
http://home.iprimus.com.au/cmckeown/foundry.htm
http://www.angelfire.com/tx5/hite/furnace.html

[obseq]

John,

Please do provide more details. One of our other members, Olivier, recently posted an image of a bronze female torso he cast in his own backyard foundry.

Do you have any images of your set up? I look forward to reading more!

[Merlion]

I will provide more details if anyone is interested.
Do post us here some photos of your furnace and casting set-up.

To post pictures, here is a write-up written by Fused sometime ago.

When you click on Post Reply and a new window appears, scroll down below the Submit Reply & Preview Post to the next frame

which says Additional Options. Near the center of the box is Attach Files with a Manage Attachments.

Click on Manage Attachments, a new window appears click browse and find the image file on your computer.

Once you find it, click Open and then click upload.

There is a limit to the image size of your picture. I think it is about 70 KB.

[John Evans]

Hello people: Thank you for your interest in the "Charcoal foundry". I tried to send pictures but being limited to 75 kb makes the exercise useless. So for now I will confine myself to verbal pictures. Besides my foundry is in a very early stage of design. It will take a year or so work the bugs out.
First a little background. I am a retired research scientist, I get my jollies by inventing things. In 1992 I started to build Newfoundland's first lost wax foundry with sculptor, Luben Boykov. We call it the "Garden Foundry". It is now a mature professional sized foundry with a maximum pour capacity of 320 pounds of silicon bronze. To see some of the monuments we have cast go to <www.sculpturebyluben.com>.
A number of things motivate me to build a wood and charcoal fired foundry. 1) a loathing of ceramic shell with its complexity and constraints. Sculptors who depend on ceramic shell foundries to complete their work miss half the fun and delegate half the creativity to a bunch of technicians. 2) My facination with the story of Cellini and Perceus. I have spent many hours in Florence gaping at that huge sculpture that was created in a single pour. 3) I am a coward, I am terrified of propane and high voltage elecricity. 4) I have about 50 cords of firewood in my backyard and I have find a way to get rid of it.
Building a lost wax foundry is a two step process, the burnout kiln and the melt furnace. The furnace is relatively easy, find anything that will burn, confine it in a container and blow in a huge amount of air. To get the continuous moderate temperature needed in a burnout kiln is more complicated.
I know now that I can do this, but I need a few months to work out some details and build a little web site where I can show what I am doing with a lot of pictures.

[Landseer]

Just stick the photos on photobucket.com, follow the directions and link them here, no 75K file limit.

[John Evans]

Thank you for your photo bucket help. I will gather images and send them on in a few days,

[John Evans]

I have prepared 5 pictures (not in logical order) of the charcoal foundry taken during its first casting. The first can be seen at http://www.flickr.com/photos/92645937@N00/280261577/in/photostream/ the rest can be seen by pressing small images under "charcoalfoundry's photostream"

The pictures can be enlarged by clicking on "See different sizes" and selecting large. Please let me know if this works. I am smarter at building lost wax foundries than doing computer work.

As you can see this is a work in progress. It will be several weeks before I am ready for another casting. At which time I will send more images.

[RWJR]

Very impressive, I had no idea it could be done with wood in such a small area. How much wood do you expect to burn to make the pour? Does the 2 1/2 hour melt time effect the quality of the bronze?
Thanks Russell

[John Evans]

You ask how much wood it took. I am afraid I canot give an exact amount, it was such an exciting and panic time that we were not counting. I guess that we used about five 5 gallon buckets full of birch splits (logs split to pieces about 4" wide and 18'' long and in the last hour abour two bushels of charcoal.
I will keep closer track of the amount next time.
As far as I know it does not matter how fast you melt Silicon Bronze but it should not be heated over 2050 F (I think maybe someone out there may know better.) In our big foundry we heat bronze to 2050 F but in this pour we heated to 1950 F and it filled the mold very well.
The neat thing about low technology is that you can safely experiment without the fear of blowing yourself up or destroying expensive equipment. Next melt I am going to try to use only wood and waste cooking oil.

[PTsideshow]

Here is the grand daddy of casting forum sites Lionels story is a good read.
http://www.backyardmetalcasting.com/forums/index.php
Here is another site with supplies and info (books) http://www.budgetcastingsupply.com/
another for burners. http://ronreil.abana.org/design1.shtml
This site has a great book on converting propane tanks into all manner of furances and forges. this is another great read. http://www.bookmasters.com/skipjack/
And last but not least here is lindsay books site that has a lot of reprints of old school tech you the do it my self types. http://www.lindsaybks.com/

[fused]

Great pics John, very cool.

[Landseer]

Good urls thanks!

[iron ant]

John, That was way cool,having a blast furnace on wood floors.That is a nice size pot of bronze to pour.Very,very inspiring.Hey after all could we be just controlled piros,if you forge,cast,run kilns ect ya gotta believe...................IA

[John Evans]

Thanks to "iron ant" for your comment about my melt furnace. Yes it looks bad melting bronze on a wood floor but by using ceramic fiber insulation outside of the refractory the exterior of the furnace was cold. Much more scary was the 6 ft column of flame coming out of the top of the furnace. The next melt was done outside.

I have melted bronze 4 times with that furnace. Each melt had between 80 and 120 pounds of bronze. We had two successful castings. With this experience under my belt I have come to the conclusion that my wood fired furnace was a dismal failure, because most of the energy that should have been melting the bronze was coming out of the top of the furnace as a huge column of flame.

The problem was that the furnace design was copied from a propane fired furnace. The furnace is now history. I have taken it all apart and salvaged most of the pieces. My next furnace will be a reverberatory furnace, something like that described by Vannoccio Biringuccio in his 16th century book (The Pirotechnia)

Back in the 16th century they used charcoal to bake moulds not to melt bronze. They only used wood to melt bronze. In a reverberatory furnace the flames are kept inside the furnace and forced to beat down on wide saucer like vessel for the bronze. By the end of March I should have my new furnace finished and tested. I will let you know how it works.