I'm fairly new to the whole casting bit, just got my foundry up and running a month ago. It took me about six months to figure out how to build a natural gas burner, do to the lack of instruction on the web, so I figured I'd throw in my two cents and show how I made mine.
What I'm posting is what I've learned through trial and error. If anyone has more information or ideas I'd appreciate it if you would let me know.
That being said, I'm not responsible for the actions or ideas of anyone that reads this. There is always a risk when working on "diy" projects, especially those that involve fire. Please practice safety when engaging in any type of casting or metal work.
Step 1: Background
Just a bit of background to explain why I made the burner the way I did.
First off I'm a college student, (i.e. broke) I had to use what was readily available to me, so propane was out of the question.
The natural gas line that I had access to was only 5 psi @ 3/4", so I needed a forced air system.
I had bought the foundry (minus the burner) from a blacksmith shop I go to on the weekends, so the inlet diameter on mine was preset at 1.5" with a 1" hole going into the brick work. It's inside diameter is 10" with a 12" depth. The crucible I have is an A10 (7 5/16" inside height, 5 11/16" inside top, and 3 3/4" inside bottom; holds about 1.5 L)