ThanksPID will be there yes... Moving to the back of the forge body.
The diagrams just not to scale and I left that detail out.
"for the last 3" I have a 1" inside the 1 1/2", a 3" piece of 1/2" inside that, and finally a 3" piece of 1/4" inside that. Some folks call it a "flame holder", or whatever, for me it's most important function is to quiet the burner. Without, it literally sounds like a jet engine in the shop.....with it, it's more a gentle roar, and is tolerable, and with ear plugs in barely noticeable."
I see in your drawing you're planning the concentric rings Ed talked about in this post:
https://knifedogs.com/threads/another-burner-problem-with-pics.50416/ where he wrote
When using a 1.5" burner tube I can see the advantage of those concentric rings, they'll effectively reduce the flow to match a 1" or 1-1/4" burner tube and provide better air/gas mixing. How do you plan to build those rings (attach each size pipe together and to 1.5" burner tube)? What thickness of pipe do you plan for the rings? Since I read this in Ed's post I've been thinking about this idea and working out details.