Buy a MIG welder. Gas-shielded, 200 amps or more.
That's what I tell anybody building their first smoker. MIG is the easiest to learn, and 200 amps or better will burn into 1/4" steel in a single pass.
If you can, get a multi-process machine. It gives you stick too, and it'll run flux core without a gas bottle if you ever need that.
Here's how I'd think through the rest of it.
MIG, flux core, stick or TIG for a smoker
A smoker build is mostly 3/16" to 1/4" tank, 1/4" plate on the firebox, and some pipe. Here's how each process handles that.
- MIG (gas): easiest to learn, cleanest bead, least cleanup. This is the first-timer's machine.
- Flux core: the no-bottle option. It's messier, with more spatter, but it handles wind and outdoor work better than gas. Run it drag, not push, electrode negative, with about 3/4" of stickout.
- Stick: it works, and it's cheap. It's a steeper start if you've never welded.
- TIG: not really worth it for smoker building. It costs more, and every joint has to be ground clean of mill scale. It lays a nicer weld… a smoker doesn't need it.
What size welder for 1/4" steel
Look at two numbers on any machine. Amperage, and duty cycle. Duty cycle is how much of the time it can run before it has to cool down.
Rule of thumb, about 1 amp for every 0.001" of thickness. So 1/4" wants roughly 250 amps for a single pass.
A 200 amp machine penetrates a lot better on 1/4" than a 135 or 140 amp machine.
Already have a smaller machine? You can still do 1/4". Bevel the joint and run more than one pass instead of one hot pass. That matters more as the steel gets thicker, 3/8" to 1/2".
Dual voltage is worth having on an entry machine. A multi-process inverter will run off a standard 50 amp or 30 amp plug.
What gas to run
75/25, argon and CO2. That's the standard mix for MIG on mild steel.
Learning to weld on your first smoker
You can. I've taught complete beginners to weld.
Practice on scrap first. Cut some small squares and weld them back together before you ever touch the tank. That's just as important as the welding itself.
Then check yourself. Weld up a scrap piece, break it or bend it, and look at the broken face. Fused all the way through the root means you've got penetration. A line that never fused means you don't.
On a first build, don't worry about how pretty the beads are. Just get started.
Which welds matter
Not every weld on a smoker carries the same weight.
- The trailer frame, axle hangers and mount. These hold the weight and go down the road. A bad weld here is a real problem.
- The reverse flow baffle plate. It has to be welded solid to the walls so air can't leak down the length of the chamber.
Fit-up doesn't have to be perfect. A small, even gap up to about 3/16" is fine as long as the weld penetrates.
And the cook chamber door doesn't have to be airtight. A little smoke at the cook chamber door isn't a real problem in my opinion. Smoke pushing out the firebox door is different… that points to a draft problem in the design.
Grind it clean first
Grind to bare steel before you weld. Mill scale flakes and has to come off. Old paint and coatings too.
If that old paint might be lead-based, wear a respirator, work in a ventilated space, and wear eye and hearing protection while you grind it off.
The tank itself has to be purged with the valves out before any of this. More on that here: Buying a Used Propane Tank for a Smoker.
Where welding falls in the build
Tack everything and fit it up first. Weld it out after. Here's the full order I build in: How to Build a Smoker: The Build Order, Start to Finish.
No shop? That's covered here: How to Build a Pit Without a Shop
Where to go from here
If this is your first build, you can follow a full 500 gallon build inside SmokerBuilderU step by step, and bring your welding questions to the live Q&A every Wednesday night at 7pm Central.
Join SmokerBuilderU
If you've got the machine and want something to build, every plan set I've drawn is at smokerplans.net. Fully dimensioned, ready to download.
Browse smoker plans
PS. Practice on scrap before you touch the tank.
Questions builders ask
What is the best welder for building a smoker?
A gas-shielded MIG welder, 200 amps or more. A multi-process machine is even better, since it also gives you stick and flux core.
Can you build a smoker with a flux core welder?
Yes. It's messier, with more spatter, but you don't need a gas bottle and it handles wind and outdoor work better than gas MIG. Run it drag, electrode negative, with about 3/4" of stickout.
What size welder do I need for 1/4" steel?
About 1 amp per 0.001" of thickness, so roughly 250 amps for a single pass on 1/4". A 200 amp machine penetrates a lot better than a 135 or 140 amp machine. With a smaller machine, bevel the joint and run more than one pass.
Can a beginner weld a smoker?
Yes. Practice on scrap first, then break or bend a test piece to check your penetration. The trailer, axle mount and any reverse flow baffle are the welds that have to be sound.
What gas do I use to MIG weld a smoker?
75/25, argon and CO2. That's the standard mix for MIG on mild steel.
