Burner positioning and other forge design considerations?

[Drew Riley]

I'm piecing together parts for my first propane forge, which is going to have (at this time anyway) a single forced air burner. I'm using a 10 gallon portable air tank for the housing, and plan to line it with at least a couple inches of kao wool, followed by a coating of refractory cement.

Right now I have the front cut off, with plans to make it into a hinged door with a smaller "regular access" opening cut in for normal use. I'll probably also make some kind of pass through in the back eventually, for longer pieces, but right now that's not a huge priority, and I may hold off for now.

My next consideration/question/problem, is where or how I should insert the forced air burner...
Should it go towards the back? Dead center? Towards the front but angled toward the back? Should I do straight down from the top? Come in from the side? Angle it for a swirling effect?

This is the tank (or one very similar) that I'm using. Should I just position the burner where the fill fitting was positioned? Am I over thinking this?

I appreciate any insight/advice....

 

[Salem Straub]

It partly depends on what type of work you'll be doing. Knife stuff yes, but just forging of blades? Do you have an oven for HT? Will you be wanting to make damascus in this? Would you like to have a floor of sorts, or is usually having things welded to a handle or otherwise clamped in tongs OK for you?
If you don't need a floor, want to make damascus, and won't be heat treating much in it... I'd go with vertical Fogg style configuration. If it's more for blade forging and some HT, I'd go maybe with horizontal and a thin brick or kiln shelf floor.
If vertical, having the burner enter from either side at a slight angle to promote swirl, 3-4" under the doors or so, works well.
If horizontal, I tend to go with burner centered in the length of the shell, slight angle for swirl, and also from the side or even slightly upward form below works well for me. I always like to have the burner lower down to avoid having a chimney effect cooking my burner after shutdown.
I have not tried it, but there was some talk from folks who'd tried and liked having the burner more forward and aiming somewhat toward the back, to reduce the exit flame in front.

 

[Rick Marchand]

Salem gives good advice. I have made a dozen or so horizontal venturi forges. My next build is a blown vertical Fogg style.

For the venturi, I used to use the Zoeller Z-Burner. It works very well. These days I use the Atlas burners... they perform great, are super simple in design and are extremely affordable.

 

[Stacy E. Apelt - Bladesmith]

I used to place the burners on the tangent to the chamber in the rear at a 15 degree forward angle. After Charles at Atlas did some design work, I have switched to placing the burner in the front of the forge at a 15 degree rearward angle.

There is a bunch of forge building info in the Stickys in the PID and Forge info section.

 

[kuraki]

The only thing I could add is you may need a "pass through" hole to get it to heat as evenly as you'd like. Every forge I've built just seems to run better overall with holes front and back. The rear one can be relatively small in comparison.

 

[JTknives]

Burner in front vs back for me depends on what the forge is for. I find that for Damascus I like the burner in the rear and angled forward. You get more dragons breath out the front. This seams to sheald the billet from oxygen better then when the burner is in the front facing back. For me it seams like I get more scale build up with a front burner facing rearward. Do t know why but I’m guessing it could be sucking air in and pulling it across the billet. But I’m not an expert, just crazy.