I did all the calculations for a 120 gal smoker. The firebox size should be 20" X 23" X 23".
My question is if I put an ash tray in the bottom of the fire box is that in excess of my dimensions? So if I wanted a 3" ash tray do I increase my box height to 23" taking my cubic inches from 10580 to 12167". I plan on having my intake vents level to the fire pit to bring air into my FB and also some kind of air intake level to my cook chamber if that information helps.
I really thought building a smoker was just slapping a few pieces of metal together and calling it good. I did not realize how much of a science you guys have this broke down into.
I plan to continue reading this site over the next month before I cut anything to make sure I minimize my mistakes. From reading through a lot of this forum you seem to be building very reliable smokers that hold tem real well. I want the same for mine at the end of the day.