120 Gal Pit Build...lots o pics!

[Cat797]

I have previously had a 120 gallon smoker that I built from a propane tank with an insulated firebox. I used Feldon's calculator for my measurements. Here are my thoughts:

Your openings (air intake, FB to CC, between RF plate and bell, and Exhaust) should be bigger than the calculator says; not much, but maybe 15%-25%. The reason for this is to help with the draw. You do not want a bottle neck anywhere in the flow.....now, that's not to say that if the calculator says a 5" chimney 24" tall, that you want to put a 60" tall stack on, cause that's not the answer. However, IMNSHO, you do not want smoke to "stay" in the cook chamber. You also want your fire to go as hot as you want and to burn clean. Having some leeway on the size of your openings gives you that flexibility.

Also, on the FB end in my cooker, the RF plate was maybe 3" from the cooking grate. It doesn't make that big of difference. And, make sure you move the firebox up high enough in the cook chamber to be able to leave a 1" or so amount of material to prevent grease from running back into your firebox in the event of some catastrophe. She will become a raging inferno....

Here's a pic of my cooker, and I'm happy to discuss it further if you'd like......I documented the build on another forum, and I can share the link with you if you want.



All the best,
Ed

 

[Badgoat]

Ed,

This was terrific information! Thank you so much. I would really appreciate the link to your build for reference.

And I may pick your brain more in the future :thumb:

Dale

 

[Cat797]

Badgoat,

Here you go! http://www.thesmokering.com/forum/viewtopic.php?t=39376&highlight=

 

[Badgoat]

Couple of questions...

So, I am using 4" pipe for my exhaust. According to the calculator it needs to be 49" tall (which is flippin huge imo). And it would prevent me from getting it in and out of my garage if need be. What if I would make my exhaust a "dual" exhaust setup? According to the calculator the stacks would only need to be 13" long if I am using 8" (two 4" pipes side by side) as my new stack diameter. Would this work? pros vs cons? Is my thinking correct?

Also, I planned on using a 12" pinwheel damper from bbqsmokersupply.com which says it provides 40 sq in of air and the calculator says I need 36. What I dont understand is why does the calculator also say I need .32 number of intakes? What on earth does that mean if the inches of air is checking out??

Should start construction on the FB this weekend!

 

[Cat797]

Bad goat,

Two four inch stacks is not equal to an 8" diameter. Two 4" stacks is equal to about a 6" diameter. So plug in 6 as your diameter and both will need to be that tall.....

Ed

 

[dummy que]

nice project turn the heat up on your welder you need quick hands get some 211 wire(low hydrogen in a roll) gas cover will help some but removing the paint or any oil will help more the 211 is real easy to run turn heat up set wire speed so it mildly stubbs when you come back across the puddle halve same model of welder run nice several IRONWORKER misc. contractors i worked for used them for handrail easier to pack around than a ln22 or ln25 good luck :clap2::clap2::clap2:

 

[Badgoat]

Couple of questions.

I began mockup of my FB yesterday. It's going to be insulated. Inner box will be 23x23, 18" diameter half moon opening from FB to CC. I installed rails 7" from the bottom of the FB to promote good airflow on the fire.

My question is in regards of the air inlet. The calculator recommends 36 sq inches of airflow. A 12" Pinwheel damper from bbqsupplystore.com says it allows 40 sq inches of flow (I will buy this or just fab one myself). Well when I measured everything out and mocked it up on the door it just seems "overkill" and just so big. And maybe it's just my initial impression from looking at it and maybe someone more experienced than me could chime in. Here are some pics...
Mockup of what is going to be the door and air inlet:



Rails and Halfmoon opening:



Another shot of the opening:




Thanks everyone.

Dale

 

[Badgoat]

So...been busy last couple of weeks but had an opportunity to jump out in the garage and get things going. Got the FB pretty much done, just have to finish up the door, air inlets and then mount it. But enjoy the pics/update...













And naturally, I had to roll it into place just to see what it looked like. I feel like all I've been doing is grinding and cutting....cutting and grinding...It's nice to see it coming together.










Hopefully tomorrow I'll get the door done and then get the box mounted!! I can hardly wait, lol.

Dale

 

[mattmountz94]

Really starting to look good! Can't wait to see the finished product

 

[m-fine]

That is a serious build for a little 140 amp welder. Have you run into the duty cycle limit much or are you working slow enough it is a non-issue?

 

[Badgoat]

Haha funny you bring that up....hit the duty cycle limit 3 times today. I just cleaned my garage and hydrated during the breaks. It was damn hot in the garage today.

 

[Doug Crann]

Outstanding....

 

[bbqwilly]

Thats a cool smoker. Cant wait to see it in action.

 

[Chef Country]

on the gas vs fluxcore I would stick with the fluxcore its more versatile, if you need to go do a project outside you don't have to worry about wind blowing your gas away. another good thing about the fluxcore you don't have to do as much metal prep, I would however knock the paint off you will get a stronger weld, and a cleaner weld. the only real plus side to the gas is no slag and a cleaner looking weld. also remember if it has slag you drag. if you need any questions about the welding metal fab feel free to hit me up im under a hood on the daily

 

[bjarolim]

Hell of a job jumping in on welding and fabbing a pit.

Good looking build keep on keep in on

 

[JohnnyB]

When you weld the FB to the CC, plug some 1/4" round stock on any areas that have a good gap. You don't want to fill with the wire that much, it winds up pulling the FB quite a bit. Ask me how I know...

Looks great, it's always good to see guys doing things like this. Makes you appreciate it a whole lot more when you're all done.

 

[Badgoat]

@johnyb. Yeah, thanks for that tip. The picture is somewhat misleading. There isn't that much of a gap. The smoker was just sitting cockeyed from the hoist. A small adjustment and it fits like a glove

 

[JohnnyB]

Nice! The first one I built, I was cocky and thought I could just freehand it. Haha, nope. I filled so much that my FB pulled down about 1/2" at the very end. Now, I carefully mark them and take my time to make sure it's level and even.

 

[bjarolim]

Measure twice...cut once, words to live by from someone who is a metal fab "specialist"(sounds better in my mind than carpenters of steel).

 

[pjtexas1]

Nice work! Subscribed.