I built my offset masonry smoker almost 20 years ago now. At the time I really didn't know exactly what I wanted to do for a firebox door and the doors and top for the smokebox. I settled on a cast iron ash clean-out door for the firebox and very simple 3/4" pine planks for the SB door and top. I didn't really like any of it, but it did let me start smoking meat!
Well, it worked, so that's what I used for about 20 years. However, now the wood has warped so much that the smokebox leaks like a sieve and I never did like the firebox flue control, nor the door.
So. New everything. Let's start with a couple photos of the old setup. Below is the old firebox door and vent (of sorts anyway - just a pipe and a hunk of wood jammed into it).
And the picture below shows the original smokebox door and top.
Now for the upgrades. Below is a pic of the smokebox today - installing a steel lintel of sorts. I will be roughly doubling the size of the smokebox. The new top will be a dome (19" radius semicircle). So I will have the original lower portion of the smokebox that will have two doors that are hinged on the sides and that close in the center. The top semi-circle door will be one-piece and hinged on the bottom (hinges will be welded to the steel bar in the picture.
In pic below I knocked out the lower two-bricks of the face of the firebox - now the firebox opening is the full size of the firebox. It will have the steel frame you see below. I have a piece of 3/16" plate steel for the door - hinged on the left side. Damper vents will be in door - one or two at the bottom and one up higher.
Below is pic of the back of the new dome top. The top that you see is three ply laminated spruce (Sitka) totaling about 1/2" thick. The back is three plies of spruce (middle ply is 90 degrees to the outer and inner plies) about 1" thick and then a sheet of 3/4" ply on the inside. All laminated wood is odd number of plies set at 90 degree angles.
Below is an interior shot of the domed top. The dome is shaped by two laminated maple & spruce semicircle arches (one in front that you can see and the other is at the back. The arches are just over one inch tall. The interior ceiling surface that you see inside the dome is a piece of 20 gauge steel. There is fiberglass insulation between the steel ceiling and the outer skin of laminated spruce.
I'm in the process of making the doors right now. Below is picture of the smokebox upper door. It will be a total of 7 plies of Douglas Fir, cheap pine and spruce. Two of the spruce laminations are in the wooden panel clamps in the pic below. I haven't planed down yet the Douglas Fir outer lamination shown on top. - It'll have some pretty contrasting bookmatched striped colors.
Below is the inner lamination or Doug Fir of the upper door. I won't describe the unfortunate circumstances that led me to have to epoxy it together this way....... :-(
Below is picture of two of the spruce laminations for the upper door being glued up in the panel clamps. I just edge glued all the laminations with Titebond Three.
Below is pic of the five laminations for one of the firebox lower doors. Inner & outer Doug Fir and three inner pine laminations. All doors will be vacuum-bag laminated together with a two-part urea-formaldehyde adhesive.
Here is another shot of the top dome. I'm so happy with how this thing came out. I think it'll look pretty cool once all is together!
More later as things progress........ My smoker has been down for several months now. I'm dying for some good ribs, etc., etc., etc.!!!
Tampa Bay, Florida