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Gravity feed firebox.

post #1 of 21
Thread Starter 
Wanted to try my hand at some welding, first time, so not the prettiest job..lol. A buddy of mine offered a free chunk of 1/4"x8"x8" tube and I figured why not make a gravity feed out of it :). Just hope the damn thing works ok :). I actually had a lot of fun with the torches and welder (old AC Miller).

Funny thing...I was scouring the scrap yards for some 1/4 steel plate and could find nothing. My buddy says lets try the fabrication place around the corner, I'm thinking yeah right, they are just going to hand me a hunk of plate steel for next to nothing. So he and I wander through the shop and ask the supervisor. The guy pulls out a nice new chunk of 1/4 plate 28X38 from the cutoffs rack and says $10, plus gives me some 1/2 bar to boot! Never hurts to ask :).

Here's some pics of the progress.

I'll be pulling the SFB off my vertical and adding the chute in it's place.

The gravity feed firebox is 8x8, 48" tall. The area that holds the charcoal above the grate is 36" long. Still need to add the doors, 2" ball valve, latches, mounting flange and wrap it with insulation.

My adjustable work table :).

Will add more as it goes :).
post #2 of 21

What will keep the chute full of Charcoal from lighting up like a giant charcoal chimney?
post #3 of 21
Controlling the airflow like the Stumps or Backwoods. PDT_Armataz_01_34.gif

The other thing I think the Stumps and Backwoods guys do is make the charcoal chute smaller at the top and tapers outwards towards the bottom to minimize the chance of the charcoal "bridging" over as it feeds down.

Let us know how it works. Sounds pretty cool

post #4 of 21
interesting we are all waiting to see how this worksicon_question.gif
post #5 of 21
Thread Starter 
Dave's right, same principle as the Stumps. Doors with gaskets make it an air tight chute with a 2" ball valve controlling the air flow.

I'm hoping the 8x8 tube is large enough area to eliminate bridging. Stumps used a 6x6 tapered chute, the guys building the clones have been using the 8x8 and don't seem to have bridging problems.

Honestly...I have no idea how well this will work..lol. Not much money into it and it was a blast playing with some new tools PDT_Armataz_01_12.gif.
post #6 of 21
That looks interesting Dave and the welding looks good let us know how it works
post #7 of 21
Looks good so far. Are you going to insulate like the stumps. You'll find this to be a very efficient set it and forget it rig if you do.
post #8 of 21
Thread Starter 
Thanks guys...PDT_Armataz_01_01.gif

Got the doors, gaskets and latches on. Will take a few more pics tomorrow.

Now just need to figure out how this thing is getting mounted. Want to make it easy to remove in case I want to take the smoker somewhere. It's getting hard to lift, so has some weight to it. Also got some beefier 8" air tires going on to handle the extra weight.

Hey Trent...

The smoker already has a couple inches of insulation all around. Once I know everything is going to work ok, I plan on wrapping a couple inches insulation around the GF firebox. PDT_Armataz_01_01.gif.
post #9 of 21
Heavy is right! My Stumps is probably 700-800 pounds but rolls easily. Something to consider on the latches would be a "slam" latch...that may be a mod I make to mine. Seems I'm taking some food off or my hands are messy and I have to stop and latch it back up.
post #10 of 21
Thread Starter 
Well...here she is mounted. Still waiting on the 2" ball valve, should have it today I hope. I made a temp orifice out of some heavy duty foil..lol. Definitely needed some insulation to help the chute temp stabilize quicker. I gave it a quick wrap of fiberglass insulation and will do a better job later with some mineral wool. The fiberglass is good to 1000F which will be a little close around the firebox area. It will work ok for a temporary blanket :). I'll pretty it up later.

I left the element in the chamber off to see what the chute would do on it's own. I dumped around 12lbs of lump and hickory chunks in the chute. Still had 10" or so empty so capacity is around 15lbs of lump along with wood chunks.

It took about 1.5hrs to get the temp stable with the valve wide open. The first 30 min was with no insulation.
Once stable it cruised at 235 for 14hrs with a little tweak 2hrs in. So I'm very happy with it PDT_Armataz_01_12.gif.

I tossed a Chuckie on after letting it burn out 4hrs. Finished in 10hrs to 195. I still have about 5" of lump going in the chute, shutdown the vents to see if it would put it out.

More pics.

Some new wheels :)

And the chuckie

post #11 of 21
Very cool. Do you mix your wood in with the charcoal as you are loading it?
post #12 of 21
Thread Starter 
Thanks shawn...very happy with it :)

I did toss a some hickory in the chute with the charcoal. I'll need to play with amount and spacing of the chunks. There is also the option of adding chunks in the bottom of the firebox. The falling embers will get chunks smoking. I'll put chunks in the firebox for shorter smokes and load them in the chute for longer ones.
post #13 of 21
That is one cool machine, nice work.
post #14 of 21

Got me thinking (BAAAADDDD)

Reccomendations on lighting the rig?

How much ash builds up at the bottom door?

Would like a removable ash pan help keep the ash and embers off or away from the door and gasket? Make cleaning easier?

Do you have a waterpan or baffles inside the smoker?

Did you get the valve yet?

I have seen the adds for Stumps and others and often thought these would be great for BBQ Guru type controllers

You make it look so simple, maybe this cave man will try it. I don't know why I never put more thought into it until I saw your pics

post #15 of 21
Wow, adds a whole new dimension to a vertical smoker! Great job, and envy your induction into welding.. something someday I'd love to try if I could ever afford the tools and materials! But, I know me.. that would be dangerous. I could easily see me making a ¼" plate computer desk weighing 800 lbs. or something like that (guarantee it wouldn't wiggle while I type tho!).

Pops §§
post #16 of 21
Thread Starter 
Thanks again guys!

Pops...my Buddy next door has the tools. His son-in-law gave him the old arc welder and he doesn't really know how to weld either. Figured one of us should try and put it to use..lol.

I can light the box with a torch from the bottom grate or dump a chimney of lit coals in first, then add unlit after. Dumping the chimney of lit first would probably get the heat building quicker.

Ash not too bad with lump. I haven't cleaned out the trap yet from the trial run, below is a few pics of the ash build up after a full chute run. I'm planing to weld up a removable ash pan, maybe can get that done today. I didn't have anything to fit in there and I was impatient wanting to test it out...lol.

I've got a baffle in the smoker, no water pan. A water pan is not needed with this setup. When I flip the top to check the coal level, the chute is full of moisture from the charcoal burning. It doesn't effect the burn, but it's dripping quite a bit of water condensation. All that moisture makes moist air traveling through the smoker. Here is a link to the smoker build.


I'm still waiting on the valve. Hoping to have it show up soon :)

I did take a few short cuts with this. The Stumps clone guys usually make a larger ash box. I didn't want to make an additional box and the chute is already 8". A larger ash box would have moved the door and gasket a little further from the fire, maybe keeping them a little cooler. I put a piece of 1/4 angle along the door edge to help keep it from warping. It does get pretty hot (so does the bottom latch), but held up ok.

Ash box after first use. Not much ash considering there was 12lbs of lump in the chute and I tossed a few fist sized chunks in the ash box during the smoke.

What fell out when I opened the door.

A little ash inside the smoker.

Whats left in the chute after 14hrs. Actually more like 15.5 hrs if I count the warm up time. Still around 5" of charcoal left. Closing up the vents and intake put the fire right out saving any leftover charcoal for next time.

Next cook I'll pre-heat the smoker with the built in heating element. As the firebox comes up to temp the controller will shut the heater down and maintain setpoint temperature. I like the firebox so far :)
post #17 of 21
Thread Starter 
Here's a few more pics. Got the valve and mineral wool insulation on. Mineral wool is 3" thick. Still need to put a skin over the GF firebox. Held the insulation up for now with a few wraps of foil tape.

So far I've done a smoke at temps of 235 and 325. 2.3" of chute height = 1lb of lump. At 325 I use about 1 lb of lump per hr, maybe a little better than that because I didn't figure in the wood chunks mixed in there.

At 235 I used .65 lbs per hour not counting the wood chunks.

I did have the chamber heater on which I set to help out with the last 50° or so. Basically set the ball valve for 190 ball park temp and let the electric heater carry it up the rest of the way to 235. This way I get precise temp control and don't worry about any fluctuations while the chute temp stabilizes. Works awesome.

Chute wrapped in mineral wool insulation.

Ball valve.

Opening to control at 235.

Opening to control at 325

Welded me up a box to catch the ashes.

I drop a fist sized chunk in the chute every 5" of coal.

Couple of 12lb turkeys done at 325, finished in about 2 3/4 hrs.

Thanks for looking :).
post #18 of 21
"Welded me up a box to catch the ashes.", as well as planetary objects....jeez that box is rugged dude! Nice build.
post #19 of 21
Thread Starter 
Thanks Josh.

Yeah the ash box is a little overkill, but had leftover 1/4" scrap to use up :).
post #20 of 21
I have been away but it is looking better and better. Great looking birds! I am out of Turkey leggs and need to do a big ole batch but the prices!
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