Firebox for Weber kettle

  • Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
SMF is reader-supported. When you buy through links on our site, we may earn an affiliate commission.

speedmetal

Newbie
Original poster
Mar 15, 2025
28
65
Post Falls, Idaho
So I had the idea a while back to build an external firebox for my kettle. I had considered just doing a mailbox mod, but where is the fun in not going overboard? It is made of 3/16 hrs and the chamber is an 18" cube. It will come in just under the grate on the opposite side of the handle. I will be cutting the hole in the side of the Weber this week and I'll update with more pictures if anyone is interested. Thinking of leaving this as a modular firebox that I can move around and hook up to different cook chambers I am planning to build in the future. It is currently getting seasoned with some peanut oil as it is what I happened to have on hand.
 

Attachments

  • KIMG20250316_213536094.JPG
    KIMG20250316_213536094.JPG
    264.6 KB · Views: 64
  • KIMG20250316_213550007.JPG
    KIMG20250316_213550007.JPG
    409.4 KB · Views: 56
  • KIMG20250316_205409959.JPG
    KIMG20250316_205409959.JPG
    725.5 KB · Views: 54
The way I see it , the box sits on the ground .
I've been tossing the idea around for a couple years , but using a side fire box from a Char griller .
I was going to connect with stove pipe , and add legs to the fire box . The price of the fire box was more than I wanted to spend on the project , so went the way of an electric element .

S speedmetal Nice work on that .
 
  • Like
Reactions: BigW.
Chopsaw is indeed correct. This will just sit on the ground and I will be able to wheel the weber up to it, though I may make a cart for the weber at some point so I can more freely wheel it around. It can definitely get pricey depending on materials you use. Luckily I was able to do it all myself to keep cost down to material and my time.
 
  • Like
Reactions: chopsaw
I may make a cart for the weber at some point so I can more freely wheel it around
This was the start of mine . Only pic I had of it , the WSM was being fired up . That's actually a Happy Cooker kettle , 1974 .
The char griller fire box was going to go on the bottom shelf , and connect with a stove pipe .
20171203_145622.jpg
You may or may not be interested , but something else in the plan was this .
20221117_075739.jpg
It's a charcoal grate from an Old Smokey 22" smoker . It fits in place of the charcoal rack on a 22" kettle . I was going to use it as a diffuser / deflector with the side fire box .
You can get them on Amazon fairly cheap . There's a couple different sizes .
 
That is a nice cart. Definitely a sweet setup. I just finished cutting the hole for the firebox.
 

Attachments

  • KIMG20250317_164611341.JPG
    KIMG20250317_164611341.JPG
    618.1 KB · Views: 42
  • Like
Reactions: BigW.
That compound radius cut can be a challenge to get tight . Maybe you wanted it big ?
 
That compound radius cut can be a challenge to get tight . Maybe you wanted it big ?
I wasn't very concerned about getting it perfect on this one. I wanted the slot big for ease of removal since I am thinking this will be a modular firebox. I plan to make a sleeve to fill in the air gap at some point. If I make more I will make a template in cad software to make it perfect.
 
  • Like
Reactions: chopsaw
That's an interesting, outside-the-box idea S speedmetal

I'm definitely interested in hearing and seeing how that setup performs! First that went through my mind was, it might be difficult to keep temps down to low-n-slow range...but that's a total guess. chopsaw chopsaw 's idea of a diffuser plate could mitigate that considerably. Please let us know how it works!

Red
 
  • Like
Reactions: chopsaw
I would also make them a bit more narrow in the future. That way they can fit between the grate supports. I removed two of them in the process of installing this since I decided to make the connection 15" wide. Nothing some sheet metal and rivets can't fix though.
 
it might be difficult to keep temps down to low-n-slow range..
I was also going to move the lid handle , and run a stack in its place . Center of the lid with the diffuser . Thinking heat would even out around the outside and back to the center and out .
 
  • Like
Reactions: seenred
Awesome .
I wanted the slot big for ease of removal
Yeah , I figured there was a reason . Wasn't dishing your cut at all .
Keep posting the results .

Funny . All my kettles that are dialed in for a long smoke like to run at 260 .
 
Funny . All my kettles that are dialed in for a long smoke like to run at 260 .
Yeah, this thing is chugging right along in that range. I am playing with split sizes and logs vs chunks as I go to see what does what. It is always fun to find out.

Pork loin went on seasoned with Lawry's, coarse salt, coarse pepper, chipotle powder, chili powder and is currently at 180~ for a bit so the cook doesn't end too quickly before it can get much smoke on it.
 

Attachments

  • KIMG20250318_141735072.JPG
    KIMG20250318_141735072.JPG
    638.4 KB · Views: 11
  • Like
Reactions: chopsaw
Well, that was delicious. Cubed it up and had it with white rice. The rest will make for fantastic meal prepping. Took about 5 1/2 hours and held temp quite well. Once I get better at managing the fire in the box and work out the perfect split size this thing will be a monster. I think some wings will be next.
 

Attachments

  • KIMG20250318_181623737.JPG
    KIMG20250318_181623737.JPG
    587.1 KB · Views: 9
  • KIMG20250318_182030245.JPG
    KIMG20250318_182030245.JPG
    613.7 KB · Views: 8
  • KIMG20250318_183529083.JPG
    KIMG20250318_183529083.JPG
    368.2 KB · Views: 8
  • KIMG20250318_183555313.JPG
    KIMG20250318_183555313.JPG
    601.5 KB · Views: 11
Nice! I notice the air gaps in the corners where it slides into the kettle. Was that intentional? After watching your first cook and thinkin' about it a bit, I'd say those "air gaps" might help keep temps more manageable. Allows some air flow into the kettle that's not wood-fire heated.

Red
 
  • Like
Reactions: chopsaw
SmokingMeatForums.com is reader supported and as an Amazon Associate, we may earn commissions from qualifying purchases.

Latest posts

Hot Threads

Clicky