First cut (on first build) is the deepest.

Horizontal smokers with a side firebox and tuning plates.
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PlugUgly
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First cut (on first build) is the deepest.

Post by PlugUgly » May 8th, 2020, 10:59 am

Hello smart smoker builder peeps, I am starting on a first smoker project and wanted some advice before I make my first cut on my tank build. I have an ~8 foot long by 3 foot diameter tank I am using for this build. I want to cut a portion of the tank and offset it as the firebox to keep my material cost low as possible. I do plan on insulating the firebox with 1.5 inches of insulation and adding an inner liner. I'd like some advice to see if I am screwing it up before I cut my tank in to two parts.

1: When I put my numbers in online calculators I am ignoring the rounded ends of the tank for simplicity. I figured since the cook chamber and the firebox will each have one of the rounded ends, they would cancel out on volume.

2: I have reduced the length and diameter of my firebox to reflect insulation, but not much else like a fire grate and am at 100.6%. Is that cutting it too close?

3: I have a piece of 8 inch pipe that was a fire hydrant base I wanted to use for the stack, it's very thick walled pipe and I plan on making a collector at the grate level. The calculators say my chimney should be 24" long and that confuses me. Does that mean stack above the top of the cook chamber?

Here's a link to feldons calculator for my inputs, I hope that isn't bad form but it's easier to link than the one from here and they agree: Link to BBQ Pit Calculator

Finally here's a shot of my tank just to show what I mean by the rounded ends, pictures always help. Thanks in advance for any advice! :beer:
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towtruck
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Re: First cut (on first build) is the deepest.

Post by towtruck » May 8th, 2020, 1:25 pm

Your fire box inside volume needs to match the calculator don't worry about the grates and such. It's better to end up a tad bigger than smaller on volume. Your stack......is it steel or ductile iron? I am familiar with stand pipes for hydrants and all the one's I have been around are not made to weld on.....and yes, measure stack from top of cook chamber no matter where you mount it.



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Dirtytires
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Re: First cut (on first build) is the deepest.

Post by Dirtytires » May 8th, 2020, 2:36 pm

Did you say feldon’s?

:rulz: :rulz: :rulz: :rulz:

We don’t use that one! Make sure you follow the numbers on whatever calculator you use tho. I WOULD definitely count the bells as they add volume and will NOT cancel each other out in a 1:1 ratio.



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Re: First cut (on first build) is the deepest.

Post by PlugUgly » May 8th, 2020, 3:01 pm

towtruck wrote:
May 8th, 2020, 1:25 pm
Your fire box inside volume needs to match the calculator don't worry about the grates and such. It's better to end up a tad bigger than smaller on volume. Your stack......is it steel or ductile iron? I am familiar with stand pipes for hydrants and all the one's I have been around are not made to weld on.....and yes, measure stack from top of cook chamber no matter where you mount it.
Hmmm, I hadn't considered that about material of the pipe. To be honest it's been lying behind my shed since I got the hydrant for a yard ornament and other than knowing it's back there I hadn't thought about what it was made of. I'll have to look into it, I know very little about it beyond it's high carbon and that will make it more likely to crack. Not sure how it would act since it's not really "structural". I suppose I could TIG braze it, but that might be more work than just getting a suitable material.

Thanks for the pointer.



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Re: First cut (on first build) is the deepest.

Post by PlugUgly » May 8th, 2020, 3:09 pm

Dirtytires wrote:
May 8th, 2020, 2:36 pm
Did you say feldon’s?

:rulz: :rulz: :rulz: :rulz:

We don’t use that one! Make sure you follow the numbers on whatever calculator you use tho. I WOULD definitely count the bells as they add volume and will NOT cancel each other out in a 1:1 ratio.
I apologize again for linking that calculator, I didn't see anything in the FAQ about it and the numbers were matching, it just provided an easy to share link.

I don't understand what you mean about the bells not cancelling each other out, I'm trying to wrap my head around it and that's why I asked. I guess the volume is "worth more" in one side than the other. If It's worth more in the cook chamber, that might be a problem since I am right on the edge with the fire box...

I'll try to figure it out, the bells are pretty small but if it's important I can try to dust off some geometry. :beer:



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Re: First cut (on first build) is the deepest.

Post by Big T » May 8th, 2020, 4:26 pm

If you look at the smokerbuilder calculators at the top of the main page you will see a simple calculator to figure the volume of the bell ends. There are a few different calculators that Pete designed to help with building a smoker. You'll be fine at 100% being that it's insulated, if it wasn't then I'd recommend 105%-110% just to be safe.


Measure Twice.....Cut Three Times.

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Re: First cut (on first build) is the deepest.

Post by PlugUgly » May 9th, 2020, 7:50 am

Thanks for the advice, I'll try to get the necessary measurements to figure the end volume today. I hope to be cutting the base off that's welded on the tank today. If that goes well I want to move on to taking the threaded fittings off and maybe do some rough layout. The reason I'm stressing the firebox size first is that the first cut I want to make is that cut, giving me two smaller pieces to work with.



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Re: First cut (on first build) is the deepest.

Post by Dirtytires » May 9th, 2020, 11:56 am

Let me try this again.

If the relationship of the cc to the fb were 1:1 then all smokers would have equal size tanks for the cc and firebox. The relationship is actually closer to 3:1 which means for every 3 cubic inches of cc volume would require only 1 cubic inch of firebox.

I ran a quick number with the assumption of a 4 inch bell on your tank and came up with 2714 cubic inches. So, let’s assume you have the perfect dimensions for your pit. In your plan of them canceling out, you would be adding 2714 cubic inches to the cc AND 2714 cubic inches to the fb when in reality you should only be adding 904 cubic inches to the firebox. This would oversize your firebox by 1809 cubic inches (a little over a cubic foot).

One of our long time members designed/added our calculators and all the geometry formulas needed to build a pit. (Go Pete!) They are could at the link at the top of the page. If you have trouble finding, understanding or calculating your numbers, I would be happy to help you.

And to be fair, Fedon has a great calculator as well and some of guys use that one. Just know, however, that some of the numbers will come out a bit differently on each calculator and are not interchangeable. Pick one, and use it for ALL your calculations. They will both provide an efficient working pit.

I was just giving you a hard time....sorry.



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Re: First cut (on first build) is the deepest.

Post by PlugUgly » May 9th, 2020, 1:51 pm

I appreciate everyone's help, and the calculator at the top of the page is what brought me to the site and why I chose to join and ask my questions here. I was using that calculator all along but when it came time to share the dimensional inputs I found the other a little easier.

I did understand that it wasn't a one to one ratio, I've seen an offset smoker before of course. I was talking myself through what I thought you meant in my last point as I typed. I was afraid I had it backwards in my head, but your last helpful post made it clear that adding a little more volume to my firebox was what I was by "ignoring" the rounded ends is what I wanted. I am accounting for them by sizing my fire box right at 100%, insulating it, and leaving the rounded end on both parts. That should oversize my firebox functionally and that was what I was aiming for. I'd rather have it a little larger than mathematically right at 100%. I sacrifice some cook area since I'm building it all our of the same tank, but this this is going to wildly exceed my needs, it's just a fun welding project for me and I like to build stuff and eat BBQ. :beer:

I got the bottom cut off and only melted one angle grinder that wasn't that great to begin with. All toes accounted for, too.
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Re: First cut (on first build) is the deepest.

Post by Big T » May 9th, 2020, 10:15 pm

The journey has officially begun :beer:


Measure Twice.....Cut Three Times.

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Re: First cut (on first build) is the deepest.

Post by ajfoxy » May 10th, 2020, 4:51 pm

Yep, as Big T said, you are on your way. Good luck and keep the pics coming.


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Re: First cut (on first build) is the deepest.

Post by PlugUgly » May 27th, 2020, 11:48 am

The cutting in two is done. I debated on the plasma cutter or the angle grinder, and the grinder won out of simplicity of of not having to move the tank. It did work well, and it's easy to make straight cuts. Sometimes I loose my mark when I am using the plasma cutter and run off into the weeds, I might use the the grinder on all the straight cuts on the tank.The only hang up was one of the seams had a backer strip welded in, and I didn't cut that clean through so there was a moment it was hanging up and not separating. I did it on blocks, the picture is just moving the pieces after wards.

Image

I power washed the inside out today, it's supposed to storm later but I might try to dress up all the edges quick just for safety.



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Re: First cut (on first build) is the deepest.

Post by Big T » May 27th, 2020, 5:56 pm

That's a nice tank picker upper that you've got there! It certainly makes building a big cooker a lot easier.


Measure Twice.....Cut Three Times.

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Re: First cut (on first build) is the deepest.

Post by Dirtytires » May 28th, 2020, 11:02 am

Congrats on the start.....you have a huge tank to build out. Keep us posted!



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Re: First cut (on first build) is the deepest.

Post by PlugUgly » May 29th, 2020, 2:39 pm

Big T wrote:
May 27th, 2020, 5:56 pm
That's a nice tank picker upper that you've got there! It certainly makes building a big cooker a lot easier.
It does make many things much easier, handling this tank would have been impossible without it.
Dirtytires wrote:
May 28th, 2020, 11:02 am
Congrats on the start.....you have a huge tank to build out. Keep us posted!
For sure it's a monster to me, at 36" deep the grates will be same width as my biggest smoker now is long. It will be like having almost 4 times the amount of cooking surface if I only do one set of racks. It's taking so long between updates because it's kind of an "in between" project when I'm not doing things I really should be doing instead. A hobby build.



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Re: First cut (on first build) is the deepest.

Post by Big T » May 29th, 2020, 5:30 pm

Ah, where the responsibiltes get in the way of the fun, we've all been there!


Measure Twice.....Cut Three Times.

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Re: First cut (on first build) is the deepest.

Post by Dirtytires » May 30th, 2020, 11:46 am

Yes...no fair that life gets in the way of a smoker build! It no rush tho, take your time and build it right as it’s going to last a long time.



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