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Position burner for direct heat or indirect heat? (First forge)


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I am using a propane tank for my first forge. Ive been trying to come to a good understanding of where to point the flame. My thinking behind my design is the angle and positioning of the burner will make a vortex (Nice turbulence) and avoid using the burner as a chimney when i shut the forge down. from what i understand this could have a negative impact on the longevity of the insulation and potentially drastically reduce the actual material heating efficiency.

Here is my first draft.


I'm going with the standard 2 layers of 1" 2600f inswool and roughly half an inch of refractory.

So basically i am asking if its more desirable to point the flame at the workpiece or in a manner that encourages a nicer vortex.

Also here is my Burner which works pretty great, I might add a blower to it if i can scavenge the right parts.Burner.thumb.jpg.7af7e9de1e1bc92324b7b6429f188e76.jpg

Feel free to talk xxxx about my design/thinking, you don't grow if you aren't willing to hear feedback.


Edited by Mod30
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Who's burner design are you using? I haven't seen one like that. How does it work? If you need to put a blower on it lose that design, put the gas jet on the other leg and make a proper Side Arm, its a are proven burner design.

If you don't use the rubber propane hose directly to the burner chimney effect won't hurt anything when you shut it down. If you close the choke there won't be one at all. 

The burner's alignment looks okay, sort of old school but it'll work alright. 

Frosty The Lucky.

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Its a hybrid of a bunch of designs i found online, standard venturi. it runs great without a blower but i want to add one for fun.

Also as far alignment is concerned is there an existing thread that covers the topic in detail? ive been searching for one for the last week or so to no avail.

Thanks for the timely replies!

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I believe there is a lot of discussion on the topic spread around in a number of threads.  I remember a discussion on the topic in the thread on Frosty's NARB and I'm certain it was discussed at length in the Forges 101 thread in the "Gas Forges" section.  Mikey is well-versed on the topic along with a number of people.  In the end, however, it has turned out that there is no ONE angle to set you burner.  There are too many variables to be able to calculate "perfect".  The type of burner, the diameter of the forge, the "drag" created by the flame face (kaowool would inhibit a vortex more than castable refractory for example)....all of these will affect the "best" angle for the burner.  The BEST option you have is to design your forge with the ability to adjust in mind.  First set the burner at something close to a tangent to the inside diameter of the forge and then make the burner port slightly larger than the diameter of the burner nozzle and use set screws on four sides so you can adjust the tilt slightly.  You will likely never design it perfectly unless you hire an R&D department.  Instead just build it with a good angle in mind (your drawing looks great to me) and then engineer it with the ability to adjust a little bit.  I did that with my NARB forge and used metal shims to get the exact angle that induced a beautiful vortex.  It is a sight to behold!  I fully intended to then make a bracket on the outside of the forge that holds the burner just so....but I'm still using those shims!



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If it works great without a blower; adding a blower will probably make it work a lot worse.  "I've got a really good Air/Fuel balance so I want to throw in a whole lot more air and destroy the balance!"  Now if the balance is not real good then it's not working great.  How much experience do you have with gas forges to be able to judge the burn?  (I've run into this quite a lot where new people make value judgements with out the experience needed to make them---things like anvil rings, anvil bounciness, spark testing of steel, etc.)


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Nothing wrong with tinkering at all, it's how I developed the T and NARB. In the case of the T it took me a couple years to develop a "good" flame and even then it was almost 2x the burner necessary for the forge, ahh 1.5x is probably more like it, I'm not going to dig it out and measure the old forge. When it came to NARB I came to it with probably 35 years experience tinkering and helping folks develop and tune propane burners. 

Based on my experience a random mix of designs assembled by an inexperienced person is so unlikely to work well it's hard to describe. 

A couple hints most folks claiming they built "great" (enter adjective of your choice) burners don't understand how they work. In virtually every case they have choke plates closed almost completely to get the best burn. That says in bold script, either the jet is too deep in the throat or too small.

You can make almost anything "work" with too small a jet and a choke. As closed as the choke plate is on your burner, it is already running lean or you wouldn't have to restrict the intake air. Adding a blower probably won't make it worse, it'll probably make it unworkable.

I'm offering you my 35+ years experience so you don't have to repeat my mistakes. 

Frosty The Lucky.

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Nothing wrong with tinkering---but when giving information that needs to be based on experience with no experience; it helps to let people know.  If I go to the Dr about an issue and they say; "it's nothing to worry about; but of course I have never studied this and don't know anything about it."  I high tail it to another Dr before I relax.  I have a friend who is a car mechanic telling me about a neighbor who bought a used car with no inspection telling him that "it's in great shape!"  Only had 20 codes when he connected a reader to it and required quite a lot of work from deferred maintenance.

My current burners are working great; however I've been using a propane forge for several decades and I know that mine are burning way too rich and so can be tuned to work *better*! (I expect that will be my shop time this weekend.)

I know that the internet tries to tell people that everyone's opinion has the same worth; but I still go to specialists when I need information on something. 

Blown burners are a lot easier to build and tune in my experience.  I used my first blown burner propane forge until the shell scaled away in places and I moved to where I didn't have electricity in my shop and switched to a NA forge; been using that for over 16 years now and just upgraded the burners on it and am still tuning them in---using the instructions that Frosty has provided for both the burner build and the tuning.

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