Vertical forge size/diameter

J

Jason Fry

Joined
Jun 5, 2008
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I have a horizontal venturi forge, so of course I need to build a vertical blown forge :)

I have a piece of 1/4" wall square tubing, 7 1/4" inside dimension, 14" long. This would only be able to support a 5" diameter chamber, roughly 12" high.

I also have a 10 gallon metal milk jug, 14" diameter, 20" high. This seems like overkill, as I could have a 10" or 12" by 16" or so chamber.

Will the smaller one work? Should I use the bigger jug? Or, should I keep looking for something sized in between?
 
Jason, the two most common I've seen at hammer ins and on the web are either a cylinder about the diameter of a 5 gallon bucket or oval shaped ones like mine. Most are made out of a cylinder cut length ways and weld ~5" of plate in between like mine. Mine is a beast I bought from a knifemaker at a blacksmith gathering, I'm not sure how long it is but its on the big side of oval shaped forges I've seen. Of course none of this is a hard rule, I've seen all kinds of stuff.

The only other thing I can add is assuming you want to make damascus, I like the oval because I can get a longer bar in and heat the whole thing vs a cylinder. I'm not pro at damascus for what its worth.

IMG_0260 by Clint, on Flickr

-Clint
 
Not sure how square tubing will work. Mine is 12 inch well casing pipe and Ed Caffrey took one of those, split it, added 4 inch flat pieces and made a 16" oval welding forge. Go big or go home. :D
 
Mine is 10" I think and it's Round. It has worked ok with 1" of wool but not super efficient. I just relined it with 2" thick wool and it was much better. I said was, the wool sold to me is not what I was told it was. I brought it up to welding temp and promptly melted the wool into little droplets. I am going to be making a new one here rather soon using 12" pipe and along it oval as well. The plan is to line it with soft fire brick and the cast or line it with high temp refractory. I have some that looks about identical to the muzzo stuff and rated to 3000°. I have never cast a forge let alone cast over fire brick. So we will see how it works. With the press being built I need a much larger opening and heating chamber and I would rather have a large efficient forge the a small inefficient one.
 
Yeah, I had some of that melty wool myself. Scrounged from a boiler at an oil refinery, but melts at welding temp. I figure if I'm going to have to purchase supplies to re-line, I might as well upgrade the forge altogether. I have a 15" long 5" chamber venturi burnered horizontal already, but the wool's all melted.
 
Yeah it sucks, but I did not scrounge mine I bought it. Was told it was high temp kaowool so I bought an entire box facepalm. Guess I can use it for a tempering oven.
 
Is the stuff that melted the regular temperature (2400°) ceramic wool instead of the 2700° stuff, or something vastly inferior to that?
I'm not quite ready to order materials, but I would have thought the 2400 stuff lined with 1/2" or so of mizzou would hold up. Much easier to get around here, but I'd rather not build it twice...
 
It might be the 2400° stuff I’m not really sure. I melted the area right where the burner flame hits the wall. The only coating I put on it was Rutlands furnace cement becaus that was all I had on hand.
 
I think I’m going to try removing the melted area (size of my fist) and fill with wool again or straight cartable then coat the entire lining with as thick a coating of Mizzou as I can. I’m guessing I melted that area becaus I got crazy hot right where the flame is. Funny becaus this is what happened to my last lining when I started using th3 new blower lol.
 
Refractory Wool will melt into little balls igf not coated by refractory clay. It is not intended to ever be exposed to direct flame. Patch it and coat it with satanite or similar stuff.
 
Stacy E. Apelt - Bladesmith said:
Refractory Wool will melt into little balls igf not coated by refractory clay. It is not intended to ever be exposed to direct flame. Patch it and coat it with satanite or similar stuff.
Click to expand...
Yeah that’s what happened. I’m guessing that area overheated quite quickly. It was coated but with the rutlands furnace cement. It is the gray stuff that I think is rated to 2700° but I will have to check when I get home.
 
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