Building my first gas forge. Advice needed.

G

Galen A. Light

Joined
Mar 7, 2008
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I am building my first gas forge. I purchased a used propane tank (14” dia. x48” long) that I intend to cut down for my shell (14” dia.x approx. 27”). I am really stumped on the question of more insulation or less. I am not sure if there is such a thing as insulation overkill. I am placing the fire bricks along the bottom of the shell, and I am considering running the bricks ‘half way ‘ up the side (so the flame will impinge on brick and not kaowool (see design 1 vs. design 2). What has really got me thinking is putting the fire bricks on end (design 3). This would allow me to have 4 layers of Kaowool verses 2. I believe that would be good, but I am not sure if it is just overkill. Having all that added insulation would also reduce the volume of the firing chamber and I think this would make the forge more terminally efficient. I could use some advice on how much insulation I really need. Obviously more bricks mean a heavy forge and greater expense. Thoughts?

Please let me know if link doesnt work, I havent posted a picture to a forum before and I am not sure exaclty how to do it.

http://www.geocities.com/galenalight/image001.jpg

Thanks in advance!

Galen A. Light
 
me personally would use design 2 but put 1 layer of kaowool down then the bricks and then kaowool around the top. The brick on the bottom will help when using flux, if you what to do damascus.
just my 2 cents
Eric Knight
 
Welcome to Bladeforums!

A bit of advice about volume. My first forge project had a chamber volume in the 400 or so cubic inch range. Took me for bloody ever to get it up to temp. That may also have had quite a bit to do with the massive thermal mass of the way too thick castable refractory liner I made, but overall, the forge was just too big for what I was trying to do with it.

This seems to be a fairly common mistake.

Delbert Ealy once told me that he casts his forge shells around a soccerball, then once they cure, he deflates the ball and removes it.

Del makes a rediculously huge amount of damascus, so unless you're working weird shapes that won't fit into the doorway opening of a smaller forge, you don't do yourself any favors by making it too big. If you've got enough wool to spare, use it to reduce that inner diameter as much as you can. 6" - 8" seems to be a really good workable diameter for the interior of the chamber. 8" to 12" of length, depending on what the forge is for. Do bear in mind that with a 12" long chamber, it gets really hard to heat the middle of a medium to large sized blade without overheating the tip.
 
Thanks gents, I found your replies very helpful. Without your advice I deffeintly would have made it to big. Not only would I have made it to big in diameter, but I would have made it too long as well. I hadn't considered how the length could lead to an overheated tip.

I did some work on it this weekend. I wish I had thought to take some picutes of it so I could share my progress with you...
 
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