Making a dedicated forgewelding forge question

weo

weo

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Sep 21, 2014
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Hello all. As I find more of my forge time devoted to playing with Damascus and making billets, I’m not liking the fact that I’m heating up 1413 cubic inches of space for approx. 36 cubic inches +/- of material. So I’ve decided I’ve got too much time on my hands and I need another project. I want to make a dedicated, small forge-welding forge. Here’re my options:

1.) Complete my original plan with my current forge (an 18″ length of 14″ diameter 1/4″ steel pipe with 2″ castable refractory for insulation and a 4″x10″ ribbon burner) and cast removable inserts out of Greencast to both shrink the current forge cavity and catch the flux to help preserve the outer layer of cement. Or;

2.) Recast and fix a smaller, atmospheric forge I’ve got.

My only concern is the potential hot spot in the middle of the atmospheric forger burning some material.

Any opinions? (solicited, of course)

Thanks for the input
 
Blown vertical forge if you're doing mostly damascus. Anything else will be inefficient. Google it for designs. Doesn't get much simpler.

Ribbon burners seem like a good idea, but I discovered after a lot of research that they aren't really ideal for what we do... In a horizontal forge, one blown burner pointed just right can be very even heatwise.

Cheers.

-Eric
 
I second a vertical blown forge with one 1.25" blown burner about 2" up from the bottom. The burner should be tangential and angled up at 15-20°. Put an inch of kitty litter in the bottom to catch flux. The shell can just sit on the bottom, and the lid can just sit on the shell. A fire brick lined lid and bottom works great.
The forge can be elliptical and run just as efficiently as round. Squeezing a 12" pipe oval and putting the ports at the outer vertices will allow a longer billet but keep the chamber size down. Make the ports only as wide as needed, 2.5" is good, and 1" taller than your billets, 4" is good. About 6" of space below the billet to the floor is plenty.
That would make a forge with a 12" wide by 10" long pipe squished oval into a 14X10" ellipse capable of heating 2" wide by 6" long by 3" tall billets (36 cu/in). With 2" of refractory the inner chamber would be about 10X6" and about 9" high. That would end up being about 500 cu/in.

Note about cast liners:
A cast liner needs to reside in an outer layer of wool to allow it to heat soak. Casting a 2" thick refractory shell directly inside a pipe shell won't work well. A cast liner of 1" max insulated by 1" to 2" of refractory wool will be many times more efficient as a welding forge. The outer layer of wool can be wrapped in a sheet metal shell for ease of manufacture.
While a cast liner is great in a dedicated welding forge for production work ( all day use every day), it is a lot of work and weight for a hobby forge.
A forge with 2" of Hi-Z wool and a good 3/8-1/2" of satanite/ITC-100 inner shell applied over the wool will work virtually as well as a cast liner.
 
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