Efficient forge design?

ScottRoush

ScottRoush

Joined
Jan 10, 2010
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I have a large volume blown vertical forge that I've been doing almost all of my work in.. general forging, forge welding, heat treating, etc. But I get tired of going through sacrificial bars for holding things for soaking as well as the inevitable dropping of work to the bottom. So I want to make a smaller volume horizontal forge.. using the same blower/burner for forge welding. Right now I have an air compressor tank filled with castable refractory and a 7 inch diameter space that is 24 inches long. Where would be the best placement of the burner? I've seen them with tangent arrangements as well as on top and straight down. And would it make sense to design a double burner using the single blower?

Also... would you expect a smaller volume forge to use less fuel getting up to heat.. or is it the thermal mass that is more important? My larger vertical forge is mostly kaowool by volume.. so there isn't a ton of thermal mass required to get it up to heat. Does this make sense???
 
Burt Foster MS does something similar. He Has a big blown forge for welding and has the tiniest little single burner forge for basic forging. Seems like it would be alot more efficient due to the smaller surface area to be heated, using less gas as a result. I snow this doesn't help you much but you might check out Burt's shop tour vid on YouTube and see his setup. Might give you an idea or two


http://youtu.be/wMJtOh9cTuo Here is the vid
 
Thanks for that... I hadn't seen that before. Nice shop! And cute 'little forge'.

So.. what are thoughts on burner on top vs. on a tangent from the side? And is it worth looking into creating two burners from one air/fuel source???
 
It doesn't matter to much as long as u get the circulating affect from a off canter inside volume ( giving it a swirling). I run mine on the side, in either case u need a baffle for thing with it.

To get more efficient u can route the intake air by the opening of the forge so it is preheated before the burner. A large amount of BTUs are used to heat the incoming air. If it matters much.
 
Okay.. Some of the commercially made forges I've seen have their burners directly on top so I assumed that those don't swirl.. just beat down directly. What is this baffle you are talking about???
 
The top down burners make no sense to me. Heat rises so you are fighting the natural flow of things. If you have ever used one, the burner or burners make hot spots where they blow down leaving you with a forge that heats your steel unevenly.
Castable refractory lined forges take a while to heat up, depending too on the density of the material. Kao wool forges come up to temp quickly. I am a fan of vertical forges myself...
 
I have done some research as has most people that try building there first forge and cant remember all the places I read everything. Basically from what I remember if you get some what of a swirl effect it forces the burn to stay in the forge a little longer instead of just blasting the wall and trying to exit either direction. Something along those lines.

The baffle is no more then a larger tube of metal sometimes with holes in it that basically disperses the direct fire from the burner around the knife blade. This prevents hot spots and ensures a even heat. If you have enough space in the forge and good control this probably wont be a issue but on the smaller ones it helps controlling the temp around the blade.
 
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