New reverse flow planning.

[smokeybrisket]

Hey everyone I'm starting the early stages of a new build. My boss gave me a aprox 24x39 pipe about 1/4 thick I think. It has flat caps welded onto it. I measured it the other day and forgot the measurements. I'm also in the material gathering phase. We have as pretty good sized steel pile behind work that has all kinds of pipe and tubing and angle iron I'm trying to do this on a very tight budget of a $100 probably ambitious at least I know it. I have a bunch of 1/8 diamond plate I'm going to make my fire box out of I'm debating double wall insulated that will be if material allows I will build in a ash box and nice thick grating for the fire to burn on to help with the longevity. also I have about 6 grates out of old ovens for my racks. I will have to hunt down a smoke stack, all of my seals, the handles for for the doors, thermometer and some wheels.

This will be my first stick burner I'm excited to take this project on. Any input is greatly appreciated. My head is spinning at all the numbers of how big to make openings and what not so any input on best calculations to follow I would appreciate it, I try to do as much research as I can before I ask on the forums.

I have 3 questions at this moment I'm sure to have a ton More.

Question 1 calculating my cooking chamber will that be the entire pipe or just the area above my baffle plate?

Question 2 if I take my 1/8 diamond plate and double it up will that suffice for the baffle plate. I know this would be my biggest hit to the budget if I had to source some 1/4 in plate, good thing is I have metal supply that has some drop from time to time.

Question 3 do I need to make a curved deflector plate at the end of my tank that has the baffle opening sense my tank is capped flat on both ends?

I will post pictures once I get going It may take a while to get started been very busy but I'll post up detailed drawing and allow yall to critique it so I can get it to as close to perfect as possible.

[OldUsedParts]

Good Luck

[Ken226]

Hi, welcome. You'll find plenty of experienced members here willing to help out. Good luck with the project.

1. For heating calculations, things like "how big does my firebox need to be", yes, you should include the volume under the reverse flow baffle. The firebox and fuel source must heat that space as well, so it counts towards the total BTU requirements.

2. The reverse flow baffle plate needs to absorb heat, then both conduct and radiate that heat into the cook chamber. 1/4" plate would be better than 1/8" plate.
If you must use 2, 1/8" diamond patterned plates welded together, then they should be arranged diamond pattern sides out away from each other, so you can tightly clamp them together before welding. Perhaps even drill 1 of the plates in lots of places and plug weld the plates together. Avoid having an air gap between the plated, you don't want the reverse flow plate to act as an insulator.
An insulated reverse flow plate wouldn't absorb, or release heat, would negate the benefits of a reverse flow setup, and would result in the reverse flow end of the smoker running hot.

3. No, it isn't needed, but it may function better. There are many ways to engineer the reverse flow chamber to cook chamber opening. Since it's your smoker, you can put as much or as little into it as you like. It would be prudent to put a lip on the end of the reverse flow plate though, to prevent grease from getting down into the reverse flow chamber.
For example, the easy way would be to use a reverse flow plate that's shorter than the width of your cook chamber, leaving the gap as the reverse flow chamber to cook chamber opening. A harder method that might give better function and looks would be to cut out some of that flat end cap, and fabricate a convex or faceted cap to allow the use of a full length reverse flow plate. Just make sure that the reverse flow to cook chamber opening is at least as big as the firebox to reverse flow chamber opening.

[smokeybrisket]

Hi, welcome. You'll find plenty of experienced members here willing to help out. Good luck with the project.

2. The reverse flow baffle plate needs to absorb heat, then both conduct and radiate that heat into the cook chamber. 1/4" plate would be better than 1/8" plate.
If you must use 2, 1/8" diamond patterned plates welded together, then they should be arranged diamond pattern sides out away from each other, so you can tightly clamp them together before welding. Perhaps even drill 1 of the plates in lots of places and plug weld the plates together. Avoid having an air gap between the plated, you don't want the reverse flow plate to act as an insulator.
An insulated reverse flow plate wouldn't absorb, or release heat, would negate the benefits of a reverse flow setup, and would result in the reverse flow end of the smoker running hot.

For example, the easy way would be to use a reverse flow plate that's shorter than the width of your cook chamber, leaving the gap as the reverse flow chamber to cook chamber opening. A harder method that might give better function and looks would be to cut out some of that flat end cap, and fabricate a convex or faceted cap to allow the use of a full length reverse flow plate. Just make sure that the reverse flow to cook chamber opening is at least as big as the firebox to reverse flow chamber opening.

I had same thought about putting plug welds to reduce the chance of the plates separating.

In the 2nd picture is that what you are picturing to us a full length RF plate?

I'm also thinking about squaring off the door to allow myself a little more room for the grates similar to what is in the first picture I will have to measure my tank again to see how much room I'm actually going to have. I'm hoping to get 2 levels of racks in there atleast on one side so I can have extra room for ribs. I typically cook shoulders and briskets they are my go to but from time to time I do ribs and sausage along with them depending on how many I need to feed.

[smokeybrisket]

Ok so I got out and measured my tank its 19.5 x 38.5 little smaller than I thought. So my ID will be 19 x 38 or so I'm thinking about 18x18x18 fire box it's a little big but itll give me room to build in a ash box under it.

Here is a couple pics of what will hopefully become my new pit.

Also any thoughts to being able to fit a second shelf for ribs?

[k.a.m.]

Hey everyone I'm starting the early stages of a new build. My boss gave me a aprox 24x39 pipe about 1/4 thick I think. It has flat caps welded onto it. I measured it the other day and forgot the measurements. I'm also in the material gathering phase. We have as pretty good sized steel pile behind work that has all kinds of pipe and tubing and angle iron I'm trying to do this on a very tight budget of a $100 probably ambitious at least I know it. I have a bunch of 1/8 diamond plate I'm going to make my fire box out of I'm debating double wall insulated that will be if material allows I will build in a ash box and nice thick grating for the fire to burn on to help with the longevity. also I have about 6 grates out of old ovens for my racks. I will have to hunt down a smoke stack, all of my seals, the handles for for the doors, thermometer and some wheels.

This will be my first stick burner I'm excited to take this project on. Any input is greatly appreciated. My head is spinning at all the numbers of how big to make openings and what not so any input on best calculations to follow I would appreciate it, I try to do as much research as I can before I ask on the forums.

I have 3 questions at this moment I'm sure to have a ton More.

Question 1 calculating my cooking chamber will that be the entire pipe or just the area above my baffle plate?
Calculate the entire vessel.

Question 2 if I take my 1/8 diamond plate and double it up will that suffice for the baffle plate. I know this would be my biggest hit to the budget if I had to source some 1/4 in plate, good thing is I have metal supply that has some drop from time to time.
It would not be my first choice to use laminated plate. A thought would be to put rails and use sections of 1/4" plate locked together with a lip on one plate. Put a 1.5" grease darn at the firebox end to keep drippings out of the firebox.

Question 3 do I need to make a curved deflector plate at the end of my tank that has the baffle opening sense my tank is capped flat on both ends?
It is not really needed but you should offset your door about 4" to allow for a spot where the heat/smoke comes up and not on your grate. Or you could add an extension like the one in the cooker pic above to compensate that area.

I will post pictures once I get going It may take a while to get started been very busy but I'll post up detailed drawing and allow yall to critique it so I can get it to as close to perfect as possible.

Here is a link to the calculator that may help. I plugged in the numbers I thought would help.
Link to BBQ Pit Calculator

[spacetrucker]

looks like you have answers looking forward to the pictures if you have a scrap pile you are working out of, slices of pipe or old oxygen bottles make great wheels, and old triple roller chain makes great hinges....

[smokeybrisket]

looks like you have answers looking forward to the pictures if you have a scrap pile you are working out of, slices of pipe or old oxygen bottles make great wheels, and old triple roller chain makes great hinges....

Its more of a left over after project pile. Theres a ton of 1/2 in 1 in 2 in 16ga lots if 1 1/8 by 1/8in 2 1/2 by 1/8 thicker walled tubing. The biggest thing out there is some 3in round tubing witch by the calculator shows to small I'm not really down for a 4ft tall stack so I will try to find someme 4 or 5in.

[spacetrucker]

the source I used to use when I was in the build mode was the scrap metal yard aka junk yard, you never know what you will find so necessity is the mother of invention there...

[smokeybrisket]

Alright did a little planning.

If someone would help me with checking my dimensions I would appreciate it.

Per Feldons calculator I need 3600 sq ft fire box. 16 H x 19 W x 16 long= 4800 sq 135% witch I have read Is good to be a little big.

My fire box opening will be half a 11in circle 11in wide 5.5 tall. For sq in opening of 46 sq in feldons shows 39 sq in recommendation. Also will sit 1 in up off the bottom so grease wont flow back into the fire box.

The opening on my RF baffle will be 19 wide x 2.5in for a opening of 47.5 sq in witch if my plate comes out to 17in wide because it sits deeper in my pipe I'll adjust accordingly.

At this time I have my cooking grate sitting 3 in off my RF baffle plate is that good? More less?

And lastly my smoke stack is 5 in x 15 grate level.

Do yall see any problems with these measurements or something I haven't thought of?

Also here's a couple pics of the left over pile I will be working out of.

[Ken226]

Your planning looks good to me. Time to start welding.

Start pondering the small stuff. Air intake adjuster designs, layouts and sizes, flu designs, handles levers and knobs etc.

[tantrum95]

Are you building a stand or is it going on a trailer?

Plans look good!

[smokeybrisket]

Your planning looks good to me. Time to start welding.

Start pondering the small stuff. Air intake adjuster designs, layouts and sizes, flu designs, handles levers and knobs etc.

The air intake plans will be per feldons I'm thinking oval cut outs to proper size to get my sq in, and a plate that will slide back and forth to open and close. Also 80% above fire gratenand 20% below is where I plan on lining up the vents.

Handles I'm thinking wood or spring style need to figure size and prices.

Are you building a stand or is it going on a trailer?

Plans look good!

Thank you, this is going on a stand with wheels as a back yard smoker.