Looked around and tried searching. How do you know you need a second burner? I built a burner but I haven’t attached it to the forge yet. I was thinking I may need a 2nd burner but can’t find any details on when a 2nd one is needed. I’m an using a old Pressure Tank as a forge.
its something to do with how many cubic inches you have inside the forge, i belive a burner with a one inch pipe, 2inch to 1 inch reducer for venturi, about 12 inch long will do up to 350 cubic inches but i could be wrong.
hope that helps 
It does Steve! I’m running a 3/4 x 10” Black Steel Nipple with a 1.5” to 3/4 reducing bell on the end and a 1” by 3/4 on the gas side. Wonder if I need to switch the reducing Bell on the business end?
you could try 1 1/4 inch and see if that makes much difference, if you go too big the flame wont stay on the end of the burner my other burner im building this weekend is 2inch to 1 inch reducer venturi end 12 inch by 1 inch nipple and 1 inch to 1 1/4 inch flare on the flame end with a .8 mm 030 mig tip , rough set up produced a beast of a flame 
I’ve been seeing a lot of mig tip set ups. This is my first forge so I don’t want to go all out just quite yet. Maybe one day soon.
i found it easier to use a mig tip as a jet than drilling a hole that is less than a mm and they are easily changed out