Replacement Firebox for My COS

[BFlynn]

What's with the "calc a later" business? I was told there would be no math.

[Mr. Bones]

Th offsets that I have, fireboxes is ~ ½ th volume of my cookin chambers, if that's of any help...

Mebbe THIS might help out, some: LINK

[Henrik]

A 20x20” firebox will be fine. No need or point in going big. But take a few photos and we’ll see.

[Dewesq55]

Thanks. I will.

[Ahumadora]

Snap some pics of what you got and I will throw in my 2 pesos...

[Dewesq55]

I am thinking about fabricating a replacement firebox for my current COS. The current one will need replacing eventually, plus, I'm in a position to do it now with COVID restrictions still keeping me away from work. Also, there is no side access to the current firebox, only from the top. I want to change that. I am also planning on using a much heavier gauge steel. The smoker's cook chamber is 39" x 17". I am planning to build a square/cuboid firebox and was wondering about dimensions. I think I'm correct that for a smoker of this size, a firebox 1/3 the volume of the cook chamber is adequate. But I wanted to know "how big is too big?" If I build one that is about 1/2 the volume of the cooker, will that work? Will I have to adjust other aspects of the cooker to allow it to work?
Henrik , Ahumadora ?