Whats wrong with my first furnace burner

What type of gas are you using?
What size pipe?
What is the gas pressure?

Hoss
 
Gas/Air not balanced for the confined space of the chamber. Turn down everything -air and gas. and tune the burner with it on the forge. Slowly bring up the gas and air until it is running right.


Strange burner design?
 
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The flame is too rich: not enough air to burn without extra air from the atmosphere. It is ok out of the forge because it can get that extra air. When you put it in the forge, it can’t get that extra air until after the rich, partially-burned mixture leaves the forge. Then it burns as the Dragons Breath.

The burner design is not very clear from the video. It certainly isn't one of the better-known designs in the bladesmithing/blacksmithing world. It does appear to be a Naturally Aspirated design. I assume it is running on Propane? The gas jet part shown in the video looks unusual. How many of them do you have available?

If you use a smaller jet at the same pressure, the burner will draw almost as much air with much less gas flow, giving a leaner mixture and completing more of the burn in the forge.

You appear to need a MUCH smaller jet. It's not easy to guess at a size, but I'd be inclined to start small and work up: making holes bigger is relatively easy. Making them smaller, less so. You will need spare jets to drill out.

I would probably start at around 0.75mm and see how it goes.

If you can modify what you have to take a MIG tip, that might be a better starting point for tuning. It's psychologically much easier to throw away a cheap mig tip than it is to throw away a hard-to-obtain part when you've drilled the hole too big. Mig tips are available in 0.6mm, 0.8mm, 0.9mm, 1.0mm, 1.2mm and 1.6mm nominal sizes. The actual holes are "about" 0.15mm bigger than the nominal wire diameter on which they are sized. You can drill the mig tips out with a pinvice and a set of microdrills by hand to fine-tune. Just go one drill size at a time and be careful. The mig tips are Copper and quite "gummy" to drill.

For a forge, we tend to want some Dragons Breath to give an Oxygen-deficient forge atmosphere that will mop up any free Oxygen before it can react with the workpiece. As the mixture gets richer, the flame temperature reduces, so we want to find the balance between a high enough flame temperature to get the job done, and a rich enough forge atmosphere to limit material loss to scale.

Try a jet. If there is no DB, try a bigger jet. If there is DB, see if it is hot enough. If it is too hot, try a bigger jet. If it is not hot enough (and you have DB), try a smaller jet. It will involve a lot of faffing about.
 
timgunn1962 said:
The flame is too rich: not enough air to burn without extra air from the atmosphere. It is ok out of the forge because it can get that extra air. When you put it in the forge, it can’t get that extra air until after the rich, partially-burned mixture leaves the forge. Then it burns as the Dragons Breath.

The burner design is not very clear from the video. It certainly isn't one of the better-known designs in the bladesmithing/blacksmithing world. It does appear to be a Naturally Aspirated design. I assume it is running on Propane? The gas jet part shown in the video looks unusual. How many of them do you have available?

If you use a smaller jet at the same pressure, the burner will draw almost as much air with much less gas flow, giving a leaner mixture and completing more of the burn in the forge.

You appear to need a MUCH smaller jet. It's not easy to guess at a size, but I'd be inclined to start small and work up: making holes bigger is relatively easy. Making them smaller, less so. You will need spare jets to drill out.

I would probably start at around 0.75mm and see how it goes.

If you can modify what you have to take a MIG tip, that might be a better starting point for tuning. It's psychologically much easier to throw away a cheap mig tip than it is to throw away a hard-to-obtain part when you've drilled the hole too big. Mig tips are available in 0.6mm, 0.8mm, 0.9mm, 1.0mm, 1.2mm and 1.6mm nominal sizes. The actual holes are "about" 0.15mm bigger than the nominal wire diameter on which they are sized. You can drill the mig tips out with a pinvice and a set of microdrills by hand to fine-tune. Just go one drill size at a time and be careful. The mig tips are Copper and quite "gummy" to drill.

For a forge, we tend to want some Dragons Breath to give an Oxygen-deficient forge atmosphere that will mop up any free Oxygen before it can react with the workpiece. As the mixture gets richer, the flame temperature reduces, so we want to find the balance between a high enough flame temperature to get the job done, and a rich enough forge atmosphere to limit material loss to scale.

Try a jet. If there is no DB, try a bigger jet. If there is DB, see if it is hot enough. If it is too hot, try a bigger jet. If it is not hot enough (and you have DB), try a smaller jet. It will involve a lot of faffing about.
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Hi thanks for your very thorough reply , I have 4 of these burners, I did as you said, the jets are 1 inch brass so I drilled them out and silver soldered a brass rod in so I had a blank canvas to start from they are burning well now. but I did not understand DB? what does that stand for?
As that is working now I am building a forced air burner the gas enters the side then into a ⅜ copper tube with 10 hole with a air disrupter ahead of it
 
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