First 250 Gallon Standard Offset Project

Horizontal smokers with a side firebox and tuning plates.
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SeaDitty
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First 250 Gallon Standard Offset Project

Post by SeaDitty » April 19th, 2018, 1:25 pm

*QUE 2001 SPACE ODYSSEY MUSIC*
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It's FINALLY time!!

I'm a long time lurker from the great state of Texas (Gig'em) who has finally decided to make the leap and build my first smoker. I've never professed to be intelligent, but I'm hoping that enough knowledge may have soaked in to allow me to be moderately successful. For where that falls short, I beg for swift corrections from the genius collective mind that is smokerbuilder.com. Any and all suggestions, recommendations, chastisements, etc. are welcome, up to and including how to use the forum correctly.

I managed to acquire a FREE 250 gallon propane tank (88" OAL, 30.25" OD), and I am currently working to organize the jumble of plans in my head down on paper. I currently plan on using a 36" length of 28" OD pipe as the base of my firebox (115% sized based on the calculator). I plan on surrounding this with a square(ish) insulated housing. Why square? I prefer the way it looks.

Rough firebox specs for the throat (178.56") and intake (66.93").
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The questions I haven't forgotten yet:

Have I gone horribly wrong in my design already?

What gauge of steel would be the best for the firebox housing? I wouldn't think heat would be too much of a factor with the insulation, but I still want it heavy duty enough to not get easily banged up.

Anyone have suggestions for insulation? A round peg in a square hole will likely leave air gaps somewhere, but I assume this wouldn't be a problem. Would it be best to use something that could form to the round firebox, or attach to the flat walls of the housing?
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Big T
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Re: First 250 Gallon Standard Offset Project

Post by Big T » April 19th, 2018, 6:47 pm

Welcome aboard!! Your overall design looks good to me. If you use rock wool batt insulation you should be able to get the majority of the area insulated pretty well providing the your outer shell is large enough. I'm not sure for the best thickness for the shell would be in the 3/32'' minimum but I tend to be pretty rough with my cookers.


Measure Twice.....Cut Three Times.

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ajfoxy
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Re: First 250 Gallon Standard Offset Project

Post by ajfoxy » April 19th, 2018, 7:16 pm

Welcome to the crew. Looks like you have the planning stage sorted. Look forward to the build.


Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.

Whether you think that you can, or that you can't, you are usually right. Henry Ford

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Re: First 250 Gallon Standard Offset Project

Post by Dirtytires » April 19th, 2018, 9:35 pm

No problem with round inside firebox but why be restricted to size when you are just going to box it anyway? Square is easier to work with on the door, vents and attachment aspects as well as the log rack. Just my 2 cents.



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ajfoxy
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Re: First 250 Gallon Standard Offset Project

Post by ajfoxy » April 20th, 2018, 3:32 am

:yth: Good advice.


Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.

Whether you think that you can, or that you can't, you are usually right. Henry Ford

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Re: First 250 Gallon Standard Offset Project

Post by Rodcrafter » April 24th, 2018, 10:01 am

:welcome:

Welcome to the crew!

I was thinking (scary I know) the same thing about the square and square for the FB? But if you're sure you want to do it your way I would recommend making the door as big as the inside FB for cleaning and loading. We tend to think only of tossing in our next stick but we are in there more than that for sure.

jm2cw


Current Smokers: Backyard RF Offset and Hybrid RF Offset trailer rig with Cowboy cooker and fish fryer, always room for more........

SeaDitty
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Re: First 250 Gallon Standard Offset Project

Post by SeaDitty » April 24th, 2018, 11:12 am

My job has me super swamped at the moment, so I haven't had time to think about this much the last week.

I'm not sure about anything! What do you mean by "restricted by size" with a round in square firebox? I want the best functioning pit I can afford, so I can be swayed on just about anything.

My thoughts on the current firebox design: I can get large diameter casing for close to nothing, and money is definitely a factor. Seems to me (based on nothing, and likely not enough to matter) that air would flow slightly better through round than square. I'm not married to it, but I do prefer the aesthetics of a square firebox. I did think about redrawing the door to be much larger for ease of loading and cleaning.

More questions I thought of:

How big is too big for a cook chamber door? It's just over 5' from seam to seam. One big door sounds nice, but not if it takes a crane to open.

There are SO MANY insulation choices online! Anyone have experience with all the different varieties (Roxul, Ceramic Fiber, etc.)? What about advice regarding thickness options, density, ease of working with, etc.?



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Re: First 250 Gallon Standard Offset Project

Post by Mokoro » April 24th, 2018, 2:07 pm

Kaowool/ceramic fibre wool is good stuff. I'm 90% through building a rectangular offset, and Im using 2" thick wool around all sides of firebox, and 1" on all sides except the base on the cook/warmer chamber.
Its very easy to use, and can easily be folded around corners or edges, and can be somewhat compressed if needed.
It appears to be bloody good at insulating the heat.. a quick test on my old uninsulated smoker proved the 2" stuff should keep the outer skin touch safe while there's a raging fire in the firebox.

Image is me testing 2" of wool. Fire was raging for hours, the wool was cool under the top steel sheet. Steel sheet was hot but due to the sun lol.
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Re: First 250 Gallon Standard Offset Project

Post by Mokoro » April 24th, 2018, 2:28 pm

Kaowool.. easy folds and can cut with a craft knife easily. We tacked in little nails on the surface of the steel to hold it in place
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Re: First 250 Gallon Standard Offset Project

Post by Dirtytires » April 26th, 2018, 6:53 pm

With a round inner firebox, you will have more issues making a wood basket, doors and vents. Inside space is definitely more cramped. Free is good but you are going to add a bunch of work hours to the build so in the end it may not really be free. Air doesn’t care much round or square.



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Re: First 250 Gallon Standard Offset Project

Post by ajfoxy » April 26th, 2018, 9:02 pm

:yth:


Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.

Whether you think that you can, or that you can't, you are usually right. Henry Ford

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