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Started my first build today!

uga fan

Smoke Blower
141
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Joined Sep 8, 2011
I have been a member here for a few years. Some may recall my current smoker the "Reverse flow flop" thread, which I modified and love using. Today I started a build for a friend of mine. Local scrap metal place had used air compressor tanks for $40, so I thought what the heck!! The one I chose is 3/16" thick which will be sufficient for what he's gonna use it for. Today I brought it home, cut the motor mounts off and removed the legs. The new plasma torch did a fantastic job at that. Then I cut the door out with a cutting wheel. I also filled in one of the small holes and ground it smooth. Used the plasma to cut out some large fittings on the ends. I'm really fascinated by this tool!! Interior of the tank had virtually no rust and the few places it did are only superficial. Dimensions of the tank are 46" by 27" diameter with a circumference of 75" I believe. Tomorrow I hope to round up some square tubing and expanded metal for the frame and shelves, while I wait on Dave to look over my measurements and set me straight with firebox dimensions. Any and all comments or suggestions are appreciated!!
 

gary s

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Looking good , off to a good start

Gary
 

uga fan

Smoke Blower
141
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Joined Sep 8, 2011
Thanks guys! Today was fairly unproductive so far. Spent half the day trying to round up metal. I went by a local trailer fabricator and he sold me his scrap pieces of expanded metal fairly cheap and was generous enough to part with some 1x2 tubing for the frame. I think the frame will be my next step until I can get some input on firebox dimensions, the opening to the cook chamber and how far in to recess the firebox into the cooker. Was hoping Dave would have stopped in already.. I've followed many builds and he seems spot on every time!! I will work on the frame in the meantime!
 

daveomak

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Bart.....

75" circ. should be about 23" ID of the tank.... or ... 27" dia. should be about 85" circ....
 

uga fan

Smoke Blower
141
16
Joined Sep 8, 2011
Ok i just rechecked and the circumference is 75".. But with the end being domed shaped I'm curious how big to make the firebox. I would have to inset it pretty far if I used a 23" wide firebox or else it would protrude. Do I scale down to say 20" and make the firebox longer to get my correct dimensions? Or go with 23" and let it be? I do like the fact that I'm under 2' wide on the metal, where I can get a sheet, rip it, and use it for the firebox and the reverse plate!!
 

daveomak

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The FB can be as big as you want.... AND, it doesn't figure in to any of the smoker calculations.... The CC determines all the calculations and dimensions.....
 

uga fan

Smoke Blower
141
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Joined Sep 8, 2011
Yeah I'm with u on that Dave, just trying to keep all the lines smooth.. I'm getting 19102 cubic inches and a recommended firebox of 6367 cubic inches. If I make the firebox 20x20x20 it puts me at 125% which is where I would like to be. I'm still dealing with the woes of an under sized firebox on my personal smoker.. Dave can u help me on figuring out how far to set the firebox in and at what height to set the reverse flow plate?
 

daveomak

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I would set the FB inside the weld bead on the tank for ease in fit up... and make the FB the same width as the RF plate for the same reason...


46 x 23 = 19,000 cu in. or so....
FB/CC opening 76 sq in or so... 5.5" high segment ED
RF plate width 19.5
Soooo, I would build the FB 20" for easy fit up to the RF plate...


The half circle shows where to figure the segment ED for the FB/CC opening.....


EDITED to fix up my ADHD / Dyslexia in the calculations.... Check for more errors.... PLEASE...
 
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uga fan

Smoke Blower
141
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Joined Sep 8, 2011
Kinda what I was thinking, but my diameter is 23" on the tank. Which brings me down to about 19,102. So will the 24x24 work or should I drop down to say 20x20 with a 20" reverse plate?
 

daveomak

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I screwed up....... SEE ABOVE POST
 

uga fan

Smoke Blower
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Joined Sep 8, 2011
Ok thats the info I needed before firing up the plasma torch!! A 20x20x20 firebox puts me at 125% per Feldon's calculator. One flaw on his page I have seen tho.. The air intakes on the firebox are for the dimensions He reccomends NOT the current size u have on your manual input. So for a good functioning firebox u need to make sure to adjust the numbers you are shooting for! Dave by your calculations, I'm coming up with an exhaust pipe 4"x 26". Now I shall practice up on my Geometry a little before ruining a tank! Thanks for the help Dave!!
 

daveomak

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4 x 26 works..... You might make it 30" above the CC for insurance.... shorter stacks have tendency to reduce the draft through the smoker... If it draws too much, you can always put a choke plate on top of the stack...
Easier than lengthening it....

Dave
 

uga fan

Smoke Blower
141
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Joined Sep 8, 2011
A choke plate on the stack is a must. I seem to adjust mine more than I do the dampers on the firebox. Thanks smoke jumper! I'm pretty sure I'm gonna be sad when my buddy comes and picks it up and takes it home!
 

crazyq

Meat Mopper
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choke plate? 

if you mean damper on the stack then there is only a couple times to use that. keep rain and debris out when not using the smoker and IF the stack is too big and your trying to make the stack volume less to create the right draft. this is not desirable tho. ideally you want to build the pit as close to specs as you can so that the stack is the right size volume wise and ALL the adjustment you should need for temp is with the FB inlet dampers. 

using the stack damper to adjust for heat and temp will cause stale smoke in the pit and cause creosote to build up in the stack which can drip down into your cook chamber. 
 

uga fan

Smoke Blower
141
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Joined Sep 8, 2011
What about hinges? Trying to decide what to go with. I know I wont use piano hinges, but I have looked at a few online, seen a few designs RibWizard came up with. Just curious what most were using when building their pits. And if they are purchased hinges, where I a good place to buy them? s
 

crazyq

Meat Mopper
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Joined Feb 7, 2014
Make em.

If u use door straps your gonna want the hinge point set back over the pit away from the door so that the strap doesnt hang or drag when opening or closing.
 

gary s

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I leave my smoke stack damper open while I am smoking, the only time I use it is when I am finished to keep out rain, bugs and whatever. Really just a rain cap.

There are a lot of styles and types of hinges out there, look around and see what you like and suits your build

Gary
 

uga fan

Smoke Blower
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Joined Sep 8, 2011
I usually open mine wide open when starting a cook to heat things up. When cooking, I have found choking it back to about 50% works great. Otherwise, my fire burns to hot, temps go up and I waste wood/charcoal. But its nice having to option to open it back up and and heat things up for cleaning after cooking!

Crazy Q, can u post me a pic of something u have made that works well? I need something that will work on the CC and the firebox. Thanks
 
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