New Reverse Flow 20 x 45

[Zimbomike]

As fate would have it, just as I found my Compressor tank, I managed to get these three pipes. 10mm thick. Not as long as I wanted , but they will do. So putting my compressor build on hold for now. Since I have three pipes (same size), I could make three smokers with square fireboxes, or two with round boxes. I am leaning towards square boxes, as I may put a warming chamber on one. Thinking of one door, two racks.

Thoughts on Square vs Round fireboxes?

[SheffSmoker]

Good find! I dream of landing some pipe like that.

If it's not as long as you'd like why not extend it by welding an extra bit on from one of the other pipes? Properly prepared egdes at 10mm thick would be a doddle to weld with a stick welder.

I've done two round FBs now, and my 3rd build is a square. I prefer square as it's way easier to work with, make vents, hang doors... but there's something asthetically pleasing about a round FB. Personal choice, and it's all yours to do as you wish.

[Dirtytires]

At 20 inch dia, two racks will be tight. Definitely possible but I might suggest making a bottom rack with enough clearance for a pork shoulder and plan on the top rack just for ribs and baked potatoes.

Agree on the square firebox....much easier to work with.

[Zimbomike]

Thanks,
I decided on the square firebox. I have a smoker builders plan for a 20 x 48 reverse flow with warming cabinet. Since it is only 3 inches shorter, I feel the plan dimensions will be ok, as far as firebox and throat sizing. That being said, I just looked at the pit calculator and the firebox size per the plan at 48 inches is only 99%. That seems a bit low. I try and shoot for 108-115%.. For the baffle gap, was thinking of trying a sliding end (50-100%). Need to work out the dam issue though. Will send pics as I go, and certainly be yelping for advice.

Thanks in advance all.

[SheffSmoker]

The only way I can envisage that working is to weld a fixed dam in place in front of the sliding one

[Zimbomike]

Thanks, will probably weld the dam at 100% and add "Tuning plate" or 2 until I get the right combination. As for throat height for the FB to CC, am I correct in placing the top of the throat opening about 2 inches below the baffle plate? Have seen it placed just directly below. I built a MACK last year, and I believe it the bottom of the baffle plate was even with the top of the throat.

[SheffSmoker]

It's as much room as you can manage really, without the baffle plate getting too close to the rack. Some install a shadow plate directly above the throat, have an air gap, then baffle plate to keep the hotspot to a minimum.

The one I'm building at the mo I'm limited with vertical space, so the baffle plate is right at the top of the throat, making the entire area under the BP the same cross sectional dimensions as the throat.

[Zimbomike]

Yes, Since I am only working with a 20 inch cooking chamber I was thinking about just one rack.. This would give me room for the baffle plate to be a couple inches above the throat. A shadow plate sounds good as well. Thanks...

[Zimbomike]

Decided to take the three cylinders and make 2 reverse flows. Using one cylinder for the fire boxes, and extending the cooking chambers to about 48 inches. Cutting and grinding of the steel done now. Next week will begin putting it all together. Cut out the 4 end plates (6mm) for one of the smokers. Not sure what to do with the firebox door, now that they will be round. I've seen the entire end plate become the door, and also seen folks cut a square door int o the round side.

[Zimbomike]

Good day all. Made some progress in cutting the throat openings on the CC and FB side plates. Made the decision to go with one cooking rack, allowing me to enough space to put the baffle plate 3 inches above the throat opening, and plenty of space between the PB and rack. I am also contemplating putting the stack slightly higher than grate level and use a plenum with an opening that almost covers the rack width. I'm sure this has been done before, just wondering the reason why its not done all the time? Maybe I'm missing something? Also, with the plenum at rack level, my stack dimensions I understand need to include the distance from the plenum to top of CC. Is this a correct assumption... Oh and by the way I did manage to find a shop hoist.. Makes things much easier.

[SheffSmoker]

Lots of folk use a plenum and lots don't. My first two I just welded the stack at the top corner of the CC and both work well. Current build I've made a small plenum just to make life easier for building, but it's still going as far up on the CC as I can get it.

Yes you got it - calcs normally use stack height measured from the top of the CC, not top of plenum.

[Dirtytires]

Disadvantage of a top mounted exhaust is you shouldn't place meat below it to prevent any dripping or crud falling on it. With that said, I have not had good luck with a low mounted exhaust on previous pits I've had so will stick with a top mounted in the future.

And the reason not everyone does it....we all have different opinions and thoughts of what works for us. None of them wrong, just different trends as manufactures try to make themselves sound better then the other guy.

[Zimbomike]

Thanks all for the responses. I think I will first try a lower mounted stack with a plenum. If it doesn't seem to work, I can always close it up and put the stack on the top.

[Zimbomike]

Howdy out there in Smokerville... Got some good work in the past couple of days. The Frame is still a work in progress, not quite sure what the end result will be yet... Want to put some type of "Wagon" turning mechanism on the front. Using larger wheels as this will be wheeled over grass and concrete. Firebox mounted, baffle plate installed, drain pipe in and doors marked for cutting. Should start cutting them today. As this is my first "Round Firebox" , I am not quite sure if I should just use a door on the end plate, or a cut out door from the top, or both... any suggestions would be appreciated.

Thanks and have a great day.

Mike

[ThinBlue]

Looking good my friend

Sent from my GM1917 using Tapatalk

[Dirtytires]

I like doors on the end of a firebox. A top firebox door dumps all your heat when opened, disrupts the airflow and typically is harder to seal.

[SheffSmoker]

[Zimbomike]

Was able to make some good progress over the last few days. Doors cut using 6 inch hand grinder. This was time consuming, as the pipe is 10mm thick. Managed to get nice clean and straight cuts using a large metal clamp across the cut line as a guide. Door came out nearly perfect, no warping or distortion (very happy about that). Welded all the side plates and firebox door in place,(took your advice and put the door on the end) exhaust stack mounted. As I was loading the pictures I noticed the stack looks tilted slightly. Went out to the workshop and used a square to check, all in line... Now to clean up the welds, throw some wheels on and give it a test burn. Not sure about finish yet. Thinking I will get it blasted then may opt for a natural look using linseed oil. Not sure if it will work though after sandblasting. Has anyone had experience using oil after sandblasting?

[Zimbomike]

Wheels on, and rolling nicely. Just to fit the door flanges and give it a test run.

[Dirtytires]

Looks good to me!

[Big T]

[Zimbomike]

Thanks for the encouragement Dirty Tires and Big T. Already thinking of my next build... Built a MACK, Big and Mini Gravity, Many UDS, Argentina and now the latest reverse flow. Was thinking of trying a standard offset next. Any other ideas?

[Frank_Cox]

Awesome build Mike!
Gimmie a holler if ya need any ideas!!
Haha I’m really good at those!
I got so many!
My current build is going to be an old school Offset with a vertical warmer on the stack end.
All built with tanks


Sent from my iPhone using Tapatalk

[Zimbomike]

Handles/latches and damper added. Nearly complete. Will season today, test flows and hopefully be smoking tomorrow. was thinking of adding a water pan in the dead spot directly above the throat, and possibly a filling tube plumbed in to add water (liquid) without opening. Can't get "Boiled" Linseed oil, so using regular linseed oil and drying with a torch. I really like the rustic look.

[Zimbomike]

Temp Gauge in, seasoning with canola oil and baking outer coat. Holds temps nice, roughly steady at 430 Deg F (225 C).. should be hot enough to season...