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Gas Forge not hot enough


ibs740

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Hi, I've just put together a propane forge. Interior DIMs 18"L X 8"H X 6"W. It is a.060" steel case, braced w/ 1/8" flat. Insulation is 2" ceramic ridgid board coated w/ IT100. End doors are 1" ridgid board. Front door has a permanent 4" X 4" opening. Rear door is closed but adjustable opening. I have 1 1/2" hard firebrick on the floor. I have 2 plumbing burners using the 1 1/4"X3/4"X1 1/4" tee. I am using a Tweeco mig nozzle (0.045" & tapered)& the pipe plugs I got were so crooked I welded a small fixture to hold my gas tubes. The gas nozzle relative to the burner end is adjustable in length. I have Zoeller stainless flares. 2 burners mounted on the top angled slightly towards the centre. I used one of the small PID controllers( cheap and work great).

My problem is that the highest temperature I can achieve is 1750 ºF @ 20psi propane inlet. I only get an orange heat which isn't enough.

When I was tuning the burners outside of the forge I found there was a very small range of movement of the flare (about 3/4" from end)where the flame would stay lit. Gas pipe in/out location didn't make a lot of difference. The flame shape and color looked good.

Is the chamber too large for this type of burner(s)? I can add another but it would just be a propane pig.

Suggestions please. Hybrid burners is one.

cheers ian

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Your burners are probably fine. Although you can use a .035 tip with the 3/4 pipe. You can only move so much air. But they are only good for about 250 cubic inches each. My calculations say you have 864 cubic inces. So either add burners. Or you could build a ribbon burner with a blower. Or make a smaller chamber.

Another thing you could do would be to take out the hard fire brick floor and put a layer of insulation down and then
a piece of kiln shelf. This will not suck up the heat like the
hard fire brick will. Just a few thoughts. Good luck! And keep us posted.

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Your burners are probably fine. Although you can use a .035 tip with the 3/4 pipe. You can only move so much air. But they are only good for about 250 cubic inches each. My calculations say you have 864 cubic inces. So either add burners. Or you could build a ribbon burner with a blower. Or make a smaller chamber.

Another thing you could do would be to take out the hard fire brick floor and put a layer of insulation down and then
a piece of kiln shelf. This will not suck up the heat like the
hard fire brick will. Just a few thoughts. Good luck! And keep us posted.


Thanks for the reply. What exactly is kiln shelf? When I made this Isort of copied a forge someone posted. Theirs was similiar length, 6"X6" but only 1" insulation. Mine's 2" and only 2" higher.
Any experience with the hybrid burners? Are their really as efficient as claimed?
cheers ian
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Thanks for the reply. What exactly is kiln shelf? When I made this Isort of copied a forge someone posted. Theirs was similiar length, 6"X6" but only 1" insulation. Mine's 2" and only 2" higher.
Any experience with the hybrid burners? Are their really as efficient as claimed?
cheers ian


Yea the kiln shelf is a material that is actually used to place pottery items on in a kiln. My kiln shelf material is 3/4" thick. What I do is I simply put kaowool under it like 1-2 inches and then put the rest of the insulation in the rest of the forge and coat with itc100. It works very well and is very durable. On my 2 burner it is a 9 inch wide piece and I have done no damage to it.

As for the hybrid burners. I have one. It works very well. But after purchasing it and seeing how it is constructed I was able to make my own knock off version of it. It saved me many dollars. You may not have the means to make such a burner i don't know but I do recommend it. I know mine work quite well. If you search for a thread called my forge story you can see pics of my forge. If you are interested.

Cheers to you! (you must be English) Todd
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That forge is large. Use a 0-60 PSI regulator. Replace your mig tips with .035 tips. Put needle valves on the top of every burner. Crank the regulator all the way down and manage the propane with the needle valves to a clean burn as hot as you want it. Replace the floor with thinner refractory (or kiln shelf) with thermal blanket under it.

If your forge still doesn't get hot, add a burner, or make a smaller forge.

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That forge is large. Use a 0-60 PSI regulator. Replace your mig tips with .035 tips. Put needle valves on the top of every burner. Crank the regulator all the way down and manage the propane with the needle valves to a clean burn as hot as you want it. Replace the floor with thinner refractory (or kiln shelf) with thermal blanket under it.

If your forge still doesn't get hot, add a burner, or make a smaller forge.



thanks. I'll dig up the shelf etc.
ian
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