March 25, 20197 yr Hey all! I am building my first forge. Basically a 2" diameter hole between 2-9" soft fire bricks. The forge will be about 113 cubic in. Mostly, I'm planning on heat treating small knives. I have access to a larger forge, but it's a bit of a drive from my house, so I wanted something small to make working a bit more convenient. Originally I was going to use a Mapp-Pro gas setup. As I've been doing my research, I'm wondering if a small venturi burner might be a better solution. Can someone help me get the right size venturi burner built? Thanks in advance for all your help!
March 25, 20197 yr didnt the burners 101 thread make sense? If you are talking about heat treating, then a large forge with lots of mass to evenly radiate heat is better than a small forge with one hot spot
March 25, 20197 yr Bobby, Mini or micro ventauri burners are actually a bit more difficult to make than more conventionally sized ones. In addition to matching the burner output to the size of the chamber (can certainly be too large as well as too small), the critical alignment details of making a ventauri burner are more pronounced with a smaller diameter burner mixing tube (1/32" out of alignment is less percentage "off" in a 1" chamber than it is in a 1/2" chamber). The Burners 101 thread does have good information on making a 1/2" or even a 3/8" burner (classified by nominal mixing tube diameter), but it will be hard to find in the thread and I would hesitate to suggest a beginning burner maker start there. You may be better off sticking with your Mapp-Pro alternative, being careful to shield and/or support the hose between the burner and the forge body. For simple heat treatment you may be able to get away with an old brass plumber's propane torch and a propane as well (I believe that there are even conversion kits to allow using larger than normal propane tanks and hoses between the two). Look for one that is larger diameter and heavy brass. Also, I'm a little confused by your math for the inner chamber volume calculation. You have described a chamber that is 2" diameter and 9" long. That gives you 23.27 cubic inches, not 113 (micro burner territory, IMHO). One last thing. Ideally for heat treatment in a gas forge you want to avoid "hot spots" on your blade (where the burner flame directly impinges on the blade surface) and heat it as evenly as possible. The larger the forge volume, in proportion to blade size, the easier that will be.
March 25, 20197 yr Welcome to IFI Bobby... I think you will find reading this will help you get the best out of the forum. READ THIS FIRST
March 25, 20197 yr Author 27 minutes ago, Latticino said: Also, I'm a little confused by your math for the inner chamber volume calculation. You have described a chamber that is 2" diameter and 9" long. That gives you 23.27 cubic inches, not 113 (micro burner territory, IMHO). Ahhh...I used the diameter instead of the radius...my bad...thanks for the correction...That changes alot. I've been reading that a 3/4" burner works for 350 cubic inches...I thought I was much closer...good catch... I did begin the burners 101 thread...not quite through it yet... Thanks guys...I promise the posts will get better!
March 25, 20197 yr Reading the Burners 101 thread is a Journey, not a Destination. When you think that you are finally done; they will post more! (Only some of us profess to hear high pitched maniacal giggling as that happens....)
March 25, 20197 yr I googled "mini burner iforgeiron.com" and got 331 results in 0.31 seconds as is suggested in the read this first thread about searching.
March 25, 20197 yr 1 hour ago, Latticino said: and I would hesitate to suggest a beginning burner maker start there By this I meant that I would be hesitant to suggest that a beginner start with a micro burner, not that the thread itself is a bad place to start (though it is certainly overwhelming)
March 25, 20197 yr A lot of good advice here; my favorite was the caution to allow a little additional diameter to keep an even temperature better; that was dead on, and all to easily overlooked! The smaller the burner the more difficult it is to build properly. Fortunately, when we get down to 1/4" equivalency, we can stop before our heir falls out. Their are finally some air/fuel torches that get hot enough and have stainless steel mixing tubes that he can employ. But the better path for a newbie is a 1/2" "T" burner in tunnel forge made from a non-refillable helium or refrigerant cylinder. The smaller the forge the less expense to build and operate. BUT, as sizes reduce the savings between one forge and another also gets reduced. That horrible word, PRACTICALITY lifts its ugly head, once again
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