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Feedback on forge?


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After watching videos and reading forum posts, I finally completed a gas forge.  I just tried it out this morning, and I'd love to get some feedback from some knowledgeable folks. 

The forge is an old helium tank, with 3 inches of kaowool liner, and a coating of satanite.  The satanite came out way more rough and crappy than I'd have liked.    The floor of the forge is hard fire brick. Photos are attached.

When I fired it up this morning, it managed to get some steel to an orage hot temperature, but the metal didn't hold it for very long.   And the forge only got hot enough to heat the bar in the back half, close to where the burner comes in.   (The burner is slightly off center, because there was a seam in the middle of the tank.)

Does the forge need to be hotter?  The burner is enough for the cubic volume in theory, but it doesn't seem to be getting the thing hot enough. 

Welcome any and all feedback.



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It looks like a burner design I've seen somewhere before. Did you follow a set of "known good" instructions?

If so, did you use the same size jet as in the instructions?

Photos in daylight are about the least helpful at showing what is going on in terms of combustion because they don't show the Dragon's Breath. Is there a lot of it? What color is it?

The most usual problem beginners make with NA burners, in my (admittedly somewhat limited) experience, is using too big a gas jet. 

This results in an excessively fuel-rich mixture and a lot of, usually yellowish, Dragons Breath.

If it's an easy thing to do, going down a size on the gas jet has a very good chance of improving matters.

If you can get a wide-angle photo across the mouth of the forge at night, it'll usually give the guys who know about such things the best chance of diagnosing the problem.

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If you bought it from Larry it should be good out of the box. Are you following his recommendations on PSI? As Tim says we need some dim light pics and at least one across the opening to evaluate it without being there. 

Assuming the burner's running properly, The first thing jumps out at me is: LOSE the fire brick! If it's a soft brick it's fragile and you'll be replacing it way more often than a person wants to pay for. If it's a hard fire brick it's a terrible heat sink and will take a LOT of fuel to get and keep hot.

Fill in the bottom of the chamber with kaowool to level and plaster a floor. It'll last a LOT longer and not waste fuel

Then make some doors, the front opening especially is WAY too large. Take a look in the gas forge section for some slick ideas for closing a freon / propane tank forge with sliding fire brick. Split hard fire brick works well. 

That's it for a hot wash review of what I see and read. Lose the brick and close the openings to the minimum size necessary to get the work in and out and provide room for exhaust.

Larry makes good burners I know I have one.

Frosty The Lucky.

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looks to me like you liner wasn't cured long enough before attempting to go up to full fire.  Are you seeing any steam or liner co9lor changes?  Most refractories benefit from a slow candling to drive out all moisture before setting.  I don't think a single 1/2 brick should be a problem for a forge of that size if the burner is performing correctly and you allow the forge enough time to heat up.  I've got two half bricks in mine and only 2" of wool and have no trouble getting up to temperature (different burner, needless to say, but still you shouldn't have that much trouble.

My recommendation is curing the liner, checking the regulator to ensure you have at least 30 psi as a maximum setting, building some form of door and getting a steel support rather than the wood!

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It is a half brick, I missed that. It should be okay, not ideal but okay.

I vote closing the openings up some, say 3" x 4" depending on the project and close the pass hole in back unless it's needed for long work.

Frosty The Lucky.

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Frostsy is right. Close down the front opening; use a movable brick wall or drill out a small opening in a high alumina kiln shelf, and leave it able to be placed closer and further away from the forge opening, until you decide how close to leave it permanently. Next, stuff some ceramic fiber between the burner and the burner port, to seal off secondary air from being induced into the forge by the burner flame. Look to see if the exhaust flame turns blue; if not, leave it in place. If you get a blue exhaust flame, take away part of the fiber, bit by bit until it stops. After you have done all that, we can discuss heat regenerative coatings.

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