Smoker stack and firebox templates: the cuts where pipe meets the cook chamber, in inches

An offset smoker is a cook chamber, a length of pipe or a rolled shell, with a firebox at one end and a stack at the other, and every joint between them is a pipe meeting a curved shell. Builders usually find those cuts with a cardboard tube trimmed until it sits. The pages below draw them from the sizes instead: set the page to inches and every result comes in fractions to the nearest 1/16 in, the thickness field takes the wall in inches or a gauge from the list, and a free account adds the full-size template on Letter sheets, to wrap round the pipe, and the DXF for a plasma table.

This page says which page draws which joint, with worked figures for a 24 in cook chamber, and what the site does not do: size the smoker, or cut anything into the domed end of a tank.

Which page for which joint

The stack on top of the cook chamber

A 6 in stack in NPS 6 pipe, 6-5/8 in outside (168 mm) with a 0.280 in wall, standing on a 24 in cook chamber (610 mm). On the Pipe Branch (Tee) page the stack is the branch and the cook chamber the main pipe. C, from the cook chamber's axis to the end of the branch, only sets how tall the band comes out: 15 in, 3 in above the top of the shell, keeps the template short.

Wrap the band round the end of the stack, its straight edge square to the pipe, mark along the curved edge and cut: the stack then sits on the shell. The page's fit is set-on, the stack resting on the outside of the shell over a hole the size of its bore; for a stack pushed through the wall instead, pick set-in on the page, and the hole becomes its outside diameter.

On a pipe cook chamber, hold the cut stack in place and scribe the hole round it. On a cook chamber rolled from plate, the Cylinder with Branch Hole page draws the whole shell with the hole in place, to cut before rolling: a 24 × 48 in chamber in 3/8 in plate is a 74-1/4 × 48 in sheet (1885 × 1219 mm).

The stack at grate level

Many builders draw the smoke from grate level: the stack leaves the side of the cook chamber below its centreline and turns up through an elbow. That stack's axis misses the cook chamber's, which is the Offset Pipe Branch. The same 6-5/8 in stack on the 24 in chamber, 6 in below the centreline (V 6), with C 16 from the chamber's axis to the end of the stub, is a 19-15/16 × 8-1/4 in band (506 × 210 mm), 3 Letter sheets.

The elbow that turns it up is the 90° Segmented Bend, in as many gores as you like. Its hole in the shell is scribed round the cut stub, as on top.

The firebox throat

When a square firebox meets the side or the bottom of a round cook chamber, the throat between them is a short rectangular duct coped to the shell. The Rectangular Tap on Pipe page draws its four walls in one strip: a 12 × 8 in throat (305 × 203 mm), 12 in along the cook chamber and 8 in across it, its outer end 16 in from the chamber's axis, in 1/4 in plate, is a 39 × 4-5/8 in strip (991 × 118 mm), 6 Letter sheets. The two walls along the chamber come out cut straight, and the two across it in the curve of the shell.

The opening in the shell: on a cook chamber rolled from plate, the Cylinder with Rectangular Hole page cuts it in the flat sheet, and the same page puts a door opening in the sheet before it is rolled. On pipe, scribe it round the throat. A firebox that butts against the flat end plate of a pipe chamber needs none of this: the opening there is a plain rectangle.

What the site does not do

• Size the smoker. The volume of the cook chamber and the sizes of the firebox, the opening between them and the stack come from a pit calculator, such as Feldon's, or from a set of plans; the pages here take the sizes you settle on.
• Cut into the domed end of a tank. A propane tank's heads are formed, and a stack or a firebox meeting one is a cut through a dome. The Nozzle on a Spherical Head page draws a nozzle parallel to the head's axis only; a stack standing up from a tank lying on its side is square to that axis, and no page draws it yet. Scribe it from the tank.
• Flat work. Doors, baffles, tuning plates, grates and charcoal baskets are flat plate, with nothing to develop.

For plasma or laser cutting, the free account exports 1 part a month in DXF; unlimited DXF export is the paid full access.

Frequently asked questions

How do I cut the hole for a smoker stack?

On a pipe cook chamber, cut the end of the stack first, with the band from the Pipe Branch (Tee) page, then hold it in place and scribe round it. On a cook chamber rolled from plate, the Cylinder with Branch Hole page cuts the hole in the flat sheet before rolling. Set-on, the hole is the bore of the stack; set-in, its outside diameter.

Can it lay out a stack or a firebox on the end of a propane tank?

Not yet. The heads of a tank are domed, and the one page for a nozzle on a dome draws it parallel to the head's axis only. Scribe those joints from the tank.

Does it size the smoker?

No. Size the cook chamber, the firebox, the opening and the stack with a pit calculator or a set of plans, then come here for the cuts.

What about the elbow and the cap on the stack?

The elbow is the 90° Segmented Bend, in as many gores as you like, and the cap is the Chinese Hat, from its rim and its height.

Is the smoker layout free?

The figures and the drawing need no account. The full-size template takes a free account, which also exports 1 part a month in DXF; unlimited DXF export is the paid full access.