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vertical forge troubleshooting


Matt Bower
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I just finished a vertical forge along the lines of Don's, shown elsewhere on this site -- with a couple differences. Last night I fired it for the first time, and I got good-sized tongues of blue dragon's breath coming out the doors of the forge, which suggested to me that the forge was running rich. I played with the burner for a good twenty minutes to half an hour, and I could not tune the problem away. By that point it was very late, so I shut down and went to bed.

 

What could be causing the problem and, more importantly, how can I fix it?

 

I mentioned that my forge is slightly different from Don's, so let me elaborate a little in case those differences are important.

 

  1. I think it's slightly shorter than Don's design, overall. I used a 5 gallon bucket as a shell, in order to double the insulation while keeping the same internal diameter as Don's design. The burner comes in at the very bottom (see below), and the doors are probably about 10" above that level.
  2. As of right now, the burner comes in right at floor level, not elevated off the floor as in Don's example. That was really an oversight on my part, but it is correctable if it's important.
  3. I'm using a T-Rex burner, for now. I can switch to a blown burner if it proves necessary.
  4. My doors are a little larger than Don's -- about 2"x3.5".

There are a couple other small differences, but I can't see how they could possibly matter for present purposes.

 

The obvious first suspect would be the tuning of my T-Rex burner, but I don't think that's the problem. First, I ran it in another forge just prior to putting it in the vertical, and there were no problems. Second, as I said, I played with the tuning (fuel pressure -- from near 0 to well over 20 PSI -- air/fuel ratio and even the location of the propane jet) quite a bit in an effort to fix the problem, and none of that really seemed to affect it.

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You want your forge to run a little rich, though too rich is a waste of fuel. Run the forge rich causes incomplete combustion in the fire chamber and the production of carbon monoxide. Carbon monoxide is good, IF YOU HAVE GOOD VENTILATION, it helps reduce decarburation. Free oxygen and carbon dioxide in the fire chamber will remove carbon from the steel.

 

Having the flame from the burner strike on the floor of the forge is not good. It will cause hot spots. Raise the height of where the burner comes into the forge to where it strikes the curve of the side of the wall towards the top. That will cause the flame to swirle and distibute itself inside the forge reducing or eliminating hot spots.

 

Doug Lester

HELP...I'm a twenty year old trapped in the body of an old man!!!

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Thanks, Doug. I didn't install the burner on a tangent because a lot of folks don't really seem to think that's necessary, and the vertical design should largely even out the hot spots. However, I do wonder if that decision may be contributing to a back pressure problem. From reading Ron Reil's site, it sounds like back pressure is likely my problem. My T-Rex is a lot more sensitive to back pressure than the blown burner that Don uses, and the doors on this forge are pretty small. So I'm wondering whether adjusting the angle of the burner port would help at all (fortunately I left myself some room to fiddle with that, if necessary) or whether I need to find a way to open up the ports a little more. (Of course I could just switch to a blown burner, too.)

 

I know that a slightly carburizing flame is a good thing, but this was ridiculous. The forge wasn't even getting hot like it should have. It was just way, way too rich.

Edited by Matt Bower
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Matt,

Can you return the burner to your original settings that worked on the previous installation. Then you might be able to turn down the volume of the LP (some type of shut off valve?) not just the pressure, until the fire gets smaller. Then adjust from there, maybe.

 

If you're looking through two open doors, eyeballing the heat may be different than you're used to. Don't know if your burner position is ideal, but I'd watch if debris doesn't affect the incoming flame. I think the Reil site says that your 14 sq in of door opening is enough, so maybe it's not back pressure.

 

Just some thoughts, good luck, Craig

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Matt,

Can you return the burner to your original settings that worked on the previous installation. Then you might be able to turn down the volume of the LP (some type of shut off valve?) not just the pressure, until the fire gets smaller. Then adjust from there, maybe.

 

If you're looking through two open doors, eyeballing the heat may be different than you're used to. Don't know if your burner position is ideal, but I'd watch if debris doesn't affect the incoming flame. I think the Reil site says that your 14 sq in of door opening is enough, so maybe it's not back pressure.

 

Just some thoughts, good luck, Craig

 

Thanks Craig. Burner settings are easy to adjust; that's no problem. I have a needle valve downstream of the regulator, and that's something I didn't really try playing with (I typically just keep it wide open and adjust fuel flow by varying pressure), so maybe I'll give it a shot. I'll check on flame obstructions, too.

Edited by Matt Bower
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