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I Forge Iron

Burner design help

Johnny K

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I am working of a double burner for my forge (yet to be built), and need some help with the design. I was breaking my head over where to start, when it occurred to me: why not use the burner system from an old barbecue? As you can see, the only modification I have done is to slide a metal tube over the orifices of the BBQ part, drilled in some air intake holes, and flared the end a very little bit. While it burns nicely, I think there is too much orange/yellow on the flame... i.e. inefficient combustion?

What should I change to get a better flame? Thicker tube? Bigger flare? More air (I think that won't work as it already has so much air that the flame occasionally "moves" as much as an inch away from the end of the pipe...) ?

Any tips/advice appreciated!


P.S. First picture is of minimum flame, second of maximum.

Flame_Min.thumb.jpg.997badadb4cf54942f51   Flame_Max.thumb.jpg.f714bad3d9916dc9ee88Air_In-take.thumb.jpg.21fd15cc3ea70ff2f1Flares.thumb.jpg.d26b5ec1b0ba2ededf3c769Controls.thumb.jpg.b37eb5c83a7d5bc786700Tank.thumb.jpg.16925c1b2f38446c7576dc6a1

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Welcome aboard John glad to have you.

At one point in your post you ask "yourself" why not use a BBQ burner in a forge. Because it's for a BBQ not a forge.

If you'd left the units as they were they might MIGHT be adequate in a bean can forge. The way you've closed the air intakes down is what's making the WAY too rich (yellow feathery) flames.

You'll be farther ahead just making the right size and number burners to fit your forge. Trying to make a BBQ burner work is a losing proposition.

Frosty The Lucky.

Edited by Frosty
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Hi Frosty, 

Thanks for the reply and welcome!

If you'd left the units as they were they might MIGHT be adequate in a bean can forge. The way you've closed the air intakes down is what's making the WAY too rich (yellow feathery) flames.

I was planning on making a sort of slightly elongated bean can forge, maybe 4 in inside diameter, and a foot long. Could you please elaborate on how I have closed the air intakes? Here's two more pictures... I didn't take the part with air intakes/burners, just up to the orifice (I believe that's what it's called?). The only thing I did was make and slide on those black pipes. Basically, I wanted to use the hose, pressure regulator, and gas fittings, as buying them individually from welding places would end up being pretty expensive, I imagine...  




BBQ Part.jpg

Exploded View.jpg

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John if you look in my long drawn out post titled "more stupid questions from a newbie" you will find a lot of answers from frosty on how to make a Frosty T Burner, parts for the burners are quite cheap.. he also explains sizing requirements and gives me lots and lots of advice 

from my own experience do some research on this site... read read and then read some more and then start asking sensible questions and everyone here starts answering away

Good luck with your endeavors 


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The BBQ system cannot deliver enough BTU for forging, the regulator is fixed and is not setup to deliver enough fuel. Research Frostys T burner and Ron Reils website for building an inexpensive burner. In a pinch you can use a needle valve to TEMPORARILY control the propane until you can get a propane regulator.

The BBQ parts would be good to make a preheating oven or a fire pit!

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You said you'd moved the choke and the pic of the burners running was over the top rich so I assumed you'd closed off the air intakes. This group of pics shows the jet orifices and they look larger than the ones I use on a 1" burner which is plenty to melt steel in a 700cu/in forge.

A 4" ID x 12" chamber is 150 cu/in so the simple ratio says a 1/2" burner. However it's so long the temperature would be pretty uneven, the area immediately around the burner nozzle. Two 1/2" burners is twice what it'd need by the basic numbers but you can turn the pressure down and it'd probably be okay.

I can't say for sure I've never run a forge that long and narrow.

I live in Alaska where freight about doubles the price of everything and I can buy a high volume 0-30psi variable pressure regulator for around $26.00 shipping included. A propane rated hose is or was the most expensive single thing in the burner set up.

The black iron plumbing parts will run about $10.00 USD, the brass fittings another $10-$15 depending on what and how you set it up.

Come to think about it if you line your bean can forge with Kaowool it'd probably work to use 2-3 propane soldering torches and not have to make anything but a little manifold ot buy the "Y" fittings to fuel them all.

Frosty The Lucky.


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Thanks for the tips!

Yes, I was actually planning to go with soldering torches, but to be able to use a 20 lb. tank seemed like an advantage... also my soldering torches are quite small. I think the BTU output of these burners is higher than that of the soldering torches I have, and they would be sufficient for my mini forge (at least for heat treating steel, my main objective), but somehow, the shape of the burner tube I crafted causes too rich a flame... I was trying to figure out how to make it "poorer", so I could have a device that is one step up (all be it a little step), from a soldering torch. The orifices are quite large, but I read somewhere that a BBQ pressure regulator outputs a very low pressure, so I guess in the end, the result is the same... 

So you say it's completely hopeless? 

If it had the same BTU output like a soldering torch or a little more, I would still be interested in getting the flame "trimmed". Theoretically at least, what is my problem? 

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pressure is approx 4/10 of a psi from a bbq regulator,  for a forge something on the order of 25 psi (adjustable) would be more in order. 
Then you will probably find that your jets are way to large.  rule of thumb seems to be .023 mig tips for 1/2 inch tube, .030-.035 mig tip for 3/4 inch tube,  .045 mig tip for 1 inch tube (inch measurements refer to nominal pipe sizes.) when things are working right these things are noisy.  What you want is for it to run perhaps a bit lean when unchoked then choke it down to neutral to slightly reducing (rich) for work. 

Good insulation is important!   once metal starts to glow it is radiating btu's at an incredible rate.  iirc radiant emissions go up with the 4th  power of the temperature (absolute.)  much of this radiated energy can be returned to the work piece by surrounding it with good insulation which catches and re radiates the energy leaving the work.

Velocity of the burning mixture is also important.  hot gas loses heat in a hurry in contact with cold metal. it is important to have a good blast going to replace the cooled gas with more high temp gas.   looking at your photos the flames appear very rich and way too low in  velocity. use a smaller jet with more pressure to get more air in the mix and increase velocity.

Have fun and  be safe.



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