Offset Smoker Plans, Any Size BBQ Smoker Pit Welding Plans, Metric and Imperial PDF with Sizing Calculator

Build an offset smoker the size you actually want.

Most smoker plans give you one smoker. This set gives you the drawings and the calculator that sizes them — so you can build around the pipe, tube or tank you can actually get hold of, instead of hunting for the one the plans were drawn for.

HOW IT WORKS

Open the Excel calculator, type in your cook chamber. The workbook works out the firebox, the throat opening, the chimney length and the number of air intakes, then gives you the cut list and the steel to buy. Change the pipe diameter and everything downstream changes with it.

The ratios are the ones pit builders have settled on over many years of building, burning and rebuilding — firebox at one third of the cook chamber, throat opening area at 0.008 of the firebox volume, chimney volume at 0.05, intake area at 0.003. They are widely published; this set applies them consistently and shows its working on a dedicated sheet.

WHAT YOU GET

9 shop drawing sheets in metric (A4, millimetres)
The same 9 sheets in imperial (US Letter, inches)
16-page assembly guide, also in both unit systems
Excel sizing calculator with 6 tabs, metric and imperial
General arrangement, cook chamber, firebox, firebox-to-chamber junction, throat and grease bridge, chimney and stand, 18-part cut list, 10-step build sequence, and the sizing method explained

DRAWN SEPARATELY, NOT CONVERTED

The metric and imperial sheets are two different drawings, not one converted into the other. A European welder cuts 500 mm, not 508. An American welder cuts 20 inches. And two of the sizing ratios are an area divided by a volume, which means they carry a unit and are quoted in inches — applied straight to millimetres they give an opening 25 times too large. Each set uses the correct constant for its own units.

NO SPECIAL KIT

No CNC, no plasma table, no rolling machine. A grinder, a welder and a drill. Works from pipe, from tube, or from a cut-down tank — the calculator takes a tank volume in gallons or litres.

THE GUIDE, NOT JUST THE DRAWINGS

The drawing sheets tell you what size. The 16-page assembly guide tells you what next — and it covers the things drawings cannot:

How to mark a curved cut on a cylinder without a rule. Why you weld the door frame on BEFORE you cut the door out, and what happens if you do it the other way. How much gap a door should have, and what to do when it has more. A weld map: which joints must be continuous and sealed, which can be stitched, and which should never be welded at all. How to tack and jump around a circle so the chamber does not pull oval. Burn-in, first fire, and what to check when it will not come up to heat.

It does not teach welding. You already know how.

THE JOINT MOST PLANS LEAVE OUT

A firebox is square. A cook chamber is round. Nobody tells you what happens where they meet — and on a chamber of this size the bottom corners of the firebox fall outside the chamber circle, so on a round end plate they have nothing to weld to. People find that out after the steel is cut.

This set draws it. At the firebox end the chamber's end plate is cut rectangular rather than round, large enough to cover the chamber circle and the firebox face with a weld land all round. Straight cuts, two flat welds, nothing to scribe onto a curve. There is a whole sheet on it, with the order of work.

THE PARTS THAT ACTUALLY MATTER

The throat between firebox and cook chamber is sized, not guessed, and it carries a grease bridge so fat cannot run into the fire. The chimney length is calculated from volume, not chosen for looks. The door is cut from the shell after the frame is welded on, so it keeps the curve and the shell cannot pull out of shape. All of it is drawn and dimensioned.

SPECIFICATIONS

Topic: Offset BBQ smoker, welding shop drawings Product type: Shop drawings with a parametric sizing calculator Format: PDF drawings plus a Microsoft Excel workbook Compatibility: any PDF reader for the drawings. Excel 2016 or later, Microsoft 365, or free Google Sheets for the calculator. Included items: 2 PDF drawing sets of 9 sheets each — one metric on A4, one imperial on US Letter — plus a 16-page assembly guide in both systems, plus an Excel calculator with 6 tabs Page count: 9 drawing sheets + 16 guide pages per unit system, 50 pages in total Instruction style: dimensioned shop drawings plus a step-by-step written guide Digital features: print at home, editable calculator that resizes the whole build Illustrations: elevations, sections, shell development, plate cutting layouts, junction detail and isometric assembly views Dimensions: A4 and US Letter, 300 dpi. Both unit systems are drawn separately. Intended user: Welders, fabrication shops, and anyone who can cut and weld steel Language: English Edition: 2026 Author and publisher: Reno Roadmap Condition: new digital file Duration: instant download, available the moment payment clears, yours to keep License: for your own use, including building to sell. Please do not resell, share or redistribute the files themselves.

A NOTE ON WHAT THIS IS NOT

These are drawings and a calculator, not a welding course. You need to be able to cut, fit and weld steel. Build to your local rules and wear the right gear.