Cupola adventures part 3

The first time was just a warm up... I hope.

This is war now! I'm pulling out all the stops, stepping my game up five or six notches. No more Mr. nice guy. And if the cupola still doesn't work... I'ma fetch the sledge hammer! -June/20/2005

The dropped contents of the cupola

Here I opened the bottom flap and let the contents drop out from the previous attempt. Actually... saying that I let the contents "drop" out is a bit misleading. I actually had to stand above the furnace on a step latter and ram the partially fused content out with a weight lifting barbell. I then cooled the hot mass with a garden watering can.

I would have called it a day at this point but I couldn't let myself give up, at least not that easily. So I decided to fire the furnace up again. Besides it was only about 3:30 PM.

Two bags of real coal

This time I have a secret weapon. I intend to melt this iron with coal! The type of rock hard coal that was used to power old-time locomotives. Hopefully these little guys will be just the ticket!

Yes I know... I know... coal isn't considered good for melting iron because it contains impurities such as sulfur that can effect the iron. But I'm willing to overlook that at this stage!

Charcoal and

Here is a comparison between charcoal created by burning wood (on the left) and this "rock" coal (on the right). The rock coal is hard, shiny and more dense. I guess this results in the increased heat and longer burning time. The charcoal is light and porous.

The coal burning in the furnace

Here's a look into the furnace soon after pouring in the coal. I poured it in a little at a time because I heard it smokes a lot. But fortunately it did not.

Notice the blue flames in the center. I think this is the result of the sulfur burning out of the coal.

The super hot furnace interior

Here's a look inside after dumping in the iron. This is clearly hotter than before!

   (Click photo for larger view)

Duct taped

The "windbelt" thing was poorly constructed and all the seems leaked air. So as a last ditch effort to increase air pressure going into the furnace I duct taped all the seams.

According to my manometer there was a static pressure of 1/4" water column in the windbelt before the duct tape. After the duct tape was applied I read 1/2" water column on the manometer! Are you ready for a good laugh? The desirable air pressure is about 2-4" water column!

Page contents copyright © 2005 by L. Oliver II - www.BackyardMetalcasting.com
The spout is plugged

At least one thing is going right for me... The bod plug is keeping the furnace spout closed. I saw some sparks coming out of it and that is a sign that iron is actually too hot and is oxidizing as it melts. At this point oxidized iron is entirely acceptable to me!

Molten slag from the furnace spot

This was about as good as it got. This is not iron, it's slag. That's all that came out the furnace. And when cool it was like the slag from an arc welding rod, shiny and black in color. I have no idea why nothing but slag came out.

   (Click photo for larger view)

Slag dripping out the spout

Here's some slag cooling on the spout. I had to keep ramming my tapping rod into the spout the keep it cleared. The rod got covered with slag and I kept dipping it in water to cool it then strike it on a cinder block to crack the slag off.

Oh well I guess you can be successful all the time.

A sculptural mass of solidified iron

Believe it or not I actually made a third furnace run with some less rusted iron to see it that helped. No iron flowed out of the spout that time either. But after I emptied the furnace I found this mass of iron. It's obvious that the iron melted but was not hot enough to stay molten so it cooled showing the shape of the drippings. This is the result after I chipped out all the charcoal that was within it.

I haven't given up though... I now have Steve Chastain's cupola book and am building a cupollette furnace with 12 or 13" bore capable of melting 60+ pounds of iron at a time!!! And this time I'll use good materials (higher quality junk)!

Check out where I sometimes go for collecting scrap iron at a sea shore

Return to cupola furnace part; 1, 2, 3 scrap iron, scrap iron 2


Copyright © 2005 by Lionel Oliver II All Rights Reserved.
This site was created Sept. 28, 2000