1st Build 100# propane cylinder

Zroadn · Post by **Zroadn** » February 28th, 2021, 10:09 am

Mornin, wanting to make my 1st smoker build. I have a 100# propane cylinder and a 30# propane cylinder. Im stuck on one of 3 paths to go because of the 100# cylinder size (14.5 x 41).
#1: Traditional offset smoker with baffle to direct firebox upward with exhaust on oppsite side grate level.
#2: Tradional offset smoker without upward baffle and utilize tuning plates.
#3: Reverse flow smoker, but with the 14" internal I am not sure there would be enough room for plate and grate. Would only have 1 cooking grate in it.
Note: The 30# propane cylinder would be my firebox. It will have an additional metal layer at the top and bottom due to its thickness. I'll be welding them offset at the ends, but it makes a difference how high they will connect depending on which of the 3 styles I go.
Recommendations would be most appreaciative for my first smaller size build. Thanks.

Dirtytires · Post by **Dirtytires** » February 28th, 2021, 11:40 am

With a 14 inch tank, you are only going to get one grate regardless of what you do. Your final (open area) grate size is going to be about 12.5 inches wide (assume a .75 inch frame). On a traditional offset, it is common to have about 1/3 of the cook chamber unusable which leaves you with about 23-25 inches of usable space (tho the rack itself should be closer to 35-36 inches). You will get a little more usable rack space from a reverse flow- I would estimate about 32-33 inches.

My first question would be if that is enough room for your needs? With the price of steel these days it may not be worth it to build a pit that you will outgrow in a short time. Hard not to use material you already have but something to consider.

Zroadn · Post by **Zroadn** » February 28th, 2021, 12:36 pm

Thanks Dirtytires, that would be enough cook area for now for me. Just the 2 of us. All I would be doing at this time would be a full brisket, or a couple Boston Butts, or a few spatchcocked chickens. On a reverse flow setup, assuming the cook grate would be at middle height of CC, would the 7" underneath it be enough room to split the difference with a 3/16 or 1/4" plate to allow good flow?

dacolson · Post by **dacolson** » February 28th, 2021, 2:39 pm

Zroadn wrote:Thanks Dirtytires, that would be enough cook area for now for me. Just the 2 of us. All I would be doing at this time would be a full brisket, or a couple Boston Butts, or a few spatchcocked chickens. On a reverse flow setup, assuming the cook grate would be at middle height of CC, would the 7" underneath it be enough room to split the difference with a 3/16 or 1/4" plate to allow good flow?

Dirtytires is spot on. You’ll want to use the pit calc to tell you how big your firebox throat is. That will determine where to put your baffle plate.
Rough and tough calcs on a 100# to 30# cc/fb, the calc calls for a throat 3” high. Please run your dimensions through the calc. Just doing rough math.
I would put a 1/4” thick shadow plate (short baffle - maybe 12”) right at the top of your throat.
Then I’d put a 1/4” baffle plate 2” above that. That puts your baffle at approx 5.25” or so. At that height, you’d have 2.5” between your baffle and grate.
It’s tight, but I think this would work in my opinion.

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Zroadn · Post by **Zroadn** » February 28th, 2021, 4:23 pm

Thanks Dave. Ill run it through the pit calcs. Preciate the feedback. The shadow baffle plate sits under the the main baffle plate, correct? Is that to keep excessive initial heat off the main baffle plate?

dacolson · Post by **dacolson** » February 28th, 2021, 7:43 pm

Zroadn wrote: ↑
February 28th, 2021, 4:23 pm
Thanks Dave. Ill run it through the pit calcs. Preciate the feedback. The shadow baffle plate sits under the the main baffle plate, correct? Is that to keep excessive initial heat off the main baffle plate?

Exactly. The baffle gets super hot right outside the throat otherwise. With the small cook surface you have, I’d recommend it. Otherwise, you’ll lose valuable grate space.

Zroadn · Post by **Zroadn** » February 28th, 2021, 8:49 pm

Good deal. Makes sense. Thanks. I ran the pit calc. Looks like I will have the room for the throat as stated. Chimney states about 15" height for a 3" round pipe. For the reverse flow chimney, is it better to come out the end above the firebox like into a welded manifold or just out the top end of the CC on the FB side of course? Thank y'all for all the advice. Want to learn right the first time. Old dog, new tricks, ha

dacolson · Post by **dacolson** » February 28th, 2021, 9:24 pm

Love it. It’s a great hobby. I’ve learned a ton here.
On a reverse flow, I’d say chimney preference is up to you. I have two with smoke collectors at grate level. A couple guys on here swear by putting the stack up high on the cc. I’d say do what you like. Just remember that stack height is measured from the top of the CC regardless of where you mount it.

Zroadn · Post by **Zroadn** » February 28th, 2021, 10:26 pm

Ok, sounds good. Preciate the top of CC measurement tip. I just need to decide 3" or 4" now and placement. Fun part will be cutting the FB to CC throat since both are curved end cylinders. Will post updates with pics as progresses. Looking forward to it

tinspark · Post by **tinspark** » March 1st, 2021, 2:07 am

That is about the same size tank as my first build (14x48). I used my old water heater and made a RF center feed.
I split mine down the middle and later laid in a few removable racks so that I could add Jalapeno poppers or even a few more racks of ribs. It essentially doubled the cook surface area. You could do something similar. If you look on page (3) of my build you will see my "goodie racks" (for lack of a better name) I Wouldn't be able to do more than a few briskets at a time in it though since they are much thicker, and they would likely hit the racks. I have had (4) spatchcocked chickens in it and a rack full of food above it, and it cooked great... .
The build is in my signature link below, and is titled "Santa Maria Smoker" I love mine..
Hope your build goes well too!

Zroadn · Post by **Zroadn** » March 1st, 2021, 8:53 am

Thanks Tinspark, thats an interesting looking build. Would be unique for sure. No limits to the imagination is what building your own is about! Tweaked me.

tinspark · Post by **tinspark** » March 1st, 2021, 12:28 pm

Zroadn wrote: ↑
March 1st, 2021, 8:53 am
Thanks Tinspark, thats an interesting looking build. Would be unique for sure. No limits to the imagination is what building your own is about! Tweaked me.

Yep, Interesting for sure:) I was in my garage with a buddy who does a lot of catering/ Weddings and such, and we were talking about that tank after it sprung a leak and was just sitting in the corner. I talked myself into doing something with it. Well, we were locked down at the start of the pandemic, and this is what I came up with.. Something unique for sure. It was a fun build and kept me out of the house for a few weeks while the wife and 3 kids played on electronic devices. That is not my thing. Probably would have needed to go to the "funny farm" if I couldn't tinker on stuff.

Zroadn · Post by **Zroadn** » March 1st, 2021, 5:31 pm

Good time killer for sure. Been tinkering to survive after retirement. Making usable stuff from nothing. Made a timber jack out of some old steel and a stick splitter out of and old axe, flywheel and sone chain. Stick splitter will come in handy for smoker.

tinspark · Post by **tinspark** » March 2nd, 2021, 4:46 pm

That log splitter has that Steam Punk vibe going on with it.
People pay good $$$ for that kind of stuff and just lay things around for the looks of it.
A lot of people sell stuff on Etsy. A lot of them are in 6 figures gross sale.
(The site shows how many sales they have so it's easy to guesstimate how much coinage they've made on their website)

Zroadn · Post by **Zroadn** » March 2nd, 2021, 8:57 pm

I enjoy retirement piddle. I'm hoping this smoker turns out well. If it does, could start on more to give my sons, but will prolly need to go with thicker material for the firebox for the long haul.

tinspark · Post by **tinspark** » March 2nd, 2021, 11:29 pm

Most guys use at least 1/4” but if your firebox tank is thin a lograck/grate will help to keep the coals off of the thin stuff a bit more. Also its best to get air under the coal bed, so be sure to place your fb air inlets at or below your fire grate in order to support better combustion. U can troll around this site to see what others have done too..
Some pretty smart and resourceful peeps here!

Zroadn · Post by **Zroadn** » March 3rd, 2021, 10:04 pm

Definitely some good ideas on this board. Was using a 30 pound propane bottle for the FB (all I have). But was going to line the bottom and the top with curved plate cut from another bottle and add the fire grate you suggested (with a basket maybe).

Dirtytires · Post by **Dirtytires** » March 4th, 2021, 10:37 am

Those 30 pound bottles are stupid small and hard to work with. I always recommend builders consider square firebox out of 0.25 material. It will last longer and be easier to work with.

Check your calculations on size....

Zroadn · Post by **Zroadn** » March 4th, 2021, 6:14 pm

Calculations are right on 100%. Would like a little more percentage though, but all I have. The frame im building will be able to compensate a .25" steel square FB down the road. The 30 pound bottle might be a fail as far as making temps in a 100 pound bottle CC as an RF smoker. Will find out. Might have to be just a charcoal basket FB, with small splits to add some smoke. Crossing fingers

Dirtytires · Post by **Dirtytires** » March 5th, 2021, 10:45 am

As long as you know the limitations....

Zroadn · Post by **Zroadn** » March 5th, 2021, 2:15 pm

I have searched the threads, but still not very clear. My 100# propane cylinder is gray in color with some rust showing. It is an old cylinder. Before I get much further in this build, is this galvanized or just old silver paint. Put a torch to the outside, no colored smoke. Put an old worn flap disk to it and it went to shiny metal very quickly. I do not recall ever seeing galvanized propane tanks, just wanted to be sure before I invest all the time in a small smoker project. Thanks.

Post by **Big T** » March 5th, 2021, 3:48 pm

It looks like paint to me and it sounds like you've tested it with fire so I think you're good to go.

dacolson · Post by **dacolson** » March 5th, 2021, 7:40 pm

Dirtytires · Post by **Dirtytires** » March 6th, 2021, 11:22 am

Sure looks like just a coating/paint to me.

Some good responses on the forum already and it sounds like you have tested it pretty effectively. Only other test I might try is to see how easy the coating is to remove with a solvent. Paint should be pretty easy to rub off on a rag with a paint stripper or acetone where a galvanized finish would not.

You would have notices some pretty obnoxious fumes/smoke from cutting out the throat if it were galvanized.

I’d say you are good to go!

Zroadn · Post by **Zroadn** » March 10th, 2021, 7:57 am

Update and question. Thanks, paint appears to be coming off without too much work. The silver is a little tougher though. Question. It is time to install the stack today on this small smoker. Was going to do the Franklin smoke collector on the end of it, but my welding is self taught and didnt want bubblegum looking welds on that much external metal, so was putting stack on top of CC. I'll lose some grate area, but is ok. Was not a party smoker. When installing the stack through either the top or the top on back corner left side, how should I terminate the inside? I'm thinking 4 options. 1) Bring it to almost grate level but bevel cut the side of pipe to open it up towards grate. 2) Attach bottom of pipe to an internal smoke collector right at top of grate running the width of grate. 3) leave it flat cut at bottom with it cut half way between entrance and grate. 4) cut it where it enters inside the top and let it draw from top of CC.
Never though it would so many critical thoughts for my first build. But, I am having fun. Just wish I was a better welder. Can stick it together, just not purdee. Thanks

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