cowboy_bc wrote:
Hi all,
I think about this subject lots and Ron you are right and you know a forge for heating shoes and for drawing clips that would work great could be made out of a $20 tiger torch and and a chunk of 8" asbestos or ceramic sewer pipe.
While you're thinking, go read:
Gas Burners for Forges, Furnaces & Kilns by Michael Porter
ISBN: 1879535203 ~ paperback ~ 216 pages
111 illustrations by the author
Looking at Toms forge design I would say that you wouldn't be able to weld and you will have a steady blast of flame out of the front.
The burner can weld in open air if you push enough gas through it.
I'm contimplating building a new killer 2 burner forge and I'm thinking the burners need to be moved forward of center and tipped backward slight so I get less blast from the door.
This will be my fourth forge. I've already been there and done that. No matter where you point the burners, the hot gas is going to come out of the door eventually . . . and since heat rises, and since your burner intakes will wind up directly over top of the door, then your burners will be sucking the hot gasses into the intake. With a straight tube burner, you are already severely limited by any kind of backpressure. The gas jet stream is what is suplying the force which draws air into the burner tube. The force is a very weak vacuum.
So if you're gonna do that design (that was my first forge) you need to plumb your burner intakes away from the door. Every time you put an elbow or a bend in the tube, you are restricting the gas flow through the tube. If you really want to use that kind of design, the best way to do it is to use an electric blower to feed air into the tube with the gas.
My current forge has a provision to adjust burner depth for changeing gas pressure caused by frosting.
You can eliminate the frosting by using a larger propane tank. That book also explains this issue and how to deal with it.
I'm also thinking of a way to point both burners to the same spot thinking this will make welding quicker better. I'm also convinced that a forge needs doors front and back.
Kevin
The taller the opening the more benefit you will get from having doors. The welding potential is determined by how many BTUs per cubic inch you can put into the chamber - 500BTUs per cubic inch is a good minimum rule of thumb if you want to weld. The number of burners you point at the hot spot is not as important as how much gas you can mix with the apropriate volume of air and direct toward the hot spot.
More reading . . .
http://ronreil.abana.org/SiteMap.html