RF Smoker Planning (and the Build)

Discussion in 'Reverse Flow' started by rasimmo, Jan 5, 2013.

  1. I have been tracking down the materials to start building what I have had in my head for a while. I have most of the major components located and I will start gatherring them up when I get home. I work offshore (7days on, 7 days off). I know that sounds like I should have plenty of time to build this thing, but it don't always work out that way. I plan to start building this week home and I would like someone to check my numbers and plan and see what yall think. I have read through most of the builds here (all 11 pages) and I have gotten a bunch of great ideas.

    I will be working with a 28" daimeter tank. the overall length is 88". The data plate is gone, but I think it is somewhere between 200 and 250. This build will be similar to the 125 Bluffton Smoker did. I am planning on putting the firebox under the cook chamber some though. I calculated the volume and ran the numbers through the pit calculator and came up with these numbers.

    Cook Chamber Volume = 37500 cu in

    Firebox Volume            = 14200 cu in

    6" stack length             = 26 in

    Firebox intake              = 43 sq in (not sure on design yet)

    Firebox to CC               = 113 sq in (my plans have it at 118)

    Under RF Plate             = 164 sq in

    End of RF Plate            = 164 sq in

    I drew out two views on draft paper we had at work. No fancy CAD system is available so that's all I have to work with. I like to draw things out and make sure of the measurements before I start cutting. I scanned them and have a PDF. I will try to attach them here if it will work. I can not get them to rotate and save on my computer so they are sideways. If someone can tell me how to fix that I will.

    Got the "Error Uploading Image" error. I'll try to figure that out.

    I think I got it, took screenshot and put it in paint, cleaned it up and saved as jpeg.

    The scanner pulled them in a little crooked, but you get the idea. Hopefully I won't build it with the lean to it.
    Last edited: Jan 6, 2013
    cajunsmoke13 likes this.
  2. jarjarchef

    jarjarchef Master of the Pit OTBS Member

    Hopefully one of the experts come by soon.

    A couple questions, because I am working out a couple builds in my head as well......

    The triangle you have towards the front of the firebox. What is it for? It looks like it would restrict the air flow.....

    Your stack damper adjustment rod. It looks like it is on the back of the stack. Would it be easier to adjust it from the same side as the door?

    Im not an expert. Just working out my plans by looking at others and asking questions.

  3. Rasimmo,  Nice looking plan for your build.  I am currently building a very similar design that I am finally getting back to work on.  Mine is a 24" diameter tank that I cut the firebox off of and mounted together in the same configuration as yours.  Couple of suggestions that I think you will find helpful in dealing with a rounded tank and firebox.  I would suggest you weld a piece of angle iron level across the top of your cook chamber and a seperate piece across the tip or your firebox temporarily while building to help with being able to keep the 2 round objects level and properly oriented with each other. Is this going to be a trailor build?  This unit is going to be really heavy to deal with if not. The only thing I don't see in your plans is any air intakes for the fire.  Are they going to be below the fire?  Are you planning any additional air intakes above the fire as recommended by a lot of folks on this site?   Best of luck on what I know will be a great build. 
    rasimmo likes this.
  4. jarjarchef,

    The triangle in the firebox is a brace. i don't plan on cutting out the bottom of the cook chamber on that end. I want to just cut a couple slits in the cook chamber and slide the firebox up into them. I don't think I will put a brace like that though. I will probably just weld a piece of angle along the bottom of it in the center. I think this will keep the flames from being directly under the RF plate and keep the temps more even. If it don't work out I can always just drag out a torch and chop it off later. That's easier than trying to add it back on. As for the stack damper adjustment, I don't think I will be able to reach it very good from the front side. The firebox door will be on the end and I don't think having the adjustment on the back will be a problem. Just my thoughts, and sometimes what is in my head is in a wad of goo that don't work out right.


    Thanks for the tip about the angle. I was still trying to figure out what to do with the air intakes. I think I figured it out and will post a pic of that. I tried to calculate what this thing would weigh and came up with 1000 - 1200 lbs. i figured the square feet of 1/4' plate (10.2 lbs per sq ft) and then doubled it for all the other stuff. It will be on a trailer with some of my other cooking stuff. I have a 6x12 trailer frame made out of 4" channel. I have a 5200# axle to put under it.

    I drew out a couple ideas for the trailer. I like the one with the smoker across the back best, but I will have to play with the balance and see how it works out. It will have an aluminum toolbox that I already have, a place for my 6 gallon and 10 gallon cast iron pots, ring with wind break big enough for 4 dutch ovens, a 2 burner cooktop, wood storage, and a deck for hauling ice chests and whatever else. My wife thinks I'm nuts and just laughs and shakes her head at me. This should be an interesting project anyway. Let me know what yall think.

    Drawing of air inlets under cook chamber on flat end of firebox. The calc says 4 is more than enough, but I want 5. I can always close them down easier than adding more. The line inside the bottom circles is the fire rack. About 1 inch above the bottom of the holes.

    Here are my ideas for the trailer. I like the colored one best, but I will have to check and see how it balances on the trailer with the other stuff. I think with the axle three feet from the back I can make it work, but I drew out a backup plan just in case.
    Last edited: Jan 6, 2013
  5. Let me try this again. The trailer drawings.

  6. I been playing again. Man, this can get carried away real quick. No plans for catering or comps, but a sink would be nice.[​IMG]

  7. solaryellow

    solaryellow Limited Mod Group Lead

    I am not sure why, but the firebox tucked under the smoke chamber is bugging me. It might just be an aesthetics thing. How close will it be to the tires?

    From a practical perspective, it might be a little cumbersome trying to clean out the firebox. It is an interesting build and I look forward to seeing some pictures of what you create. Thumbs Up
  8. bruno994

    bruno994 Master of the Pit

    Solar, I know RibWizzard has had several post talking about mounting the firebox more under the main chamber instead of true offset.  I'm sure he'll be along on this one sometime to offer up some advice.

    Rassimo, I like your trailer setup, but if your going to have a sink and a number of other items for use while on the trailer, I would think that access to the smoker while on the deck of the trailer would really be a good idea.  Either make it all accesible from the ground or the deck.  Getting up and down might prove to be more of a headache than convienence.  Just my .02... 
    Last edited: Jan 7, 2013
  9. fagesbp

    fagesbp Smoking Fanatic

    I'm in. Can't wait to see it come together. I'm kind of looking for about a hundred gallon for a patio build. Very similar to what you are doing here. Why are you going under the cc with the fb at all? I was thinking of using plate to cover the cut off ends of the tank and just mount the fb flush against the cc. Maybe you could help me fro making a big mistake in design.
  10. Thanks for the encouragement. I am excited to get started. I kinda set a goal to have everything done, tested, and dialed in by Thinksgiving. We have a camping trip planned that will include 40 or 50 people. I think something like this would come in handy for that. That seems like a long way off, but I am trying to be realistic. This is not going to happen very fast. I will try to answer some of yall's questions. Please keep them coming, it makes me think things through.

    The firebox is under the CC for some efficiency ( I think anyway) and it fits on the trailer sideways that way. I have been thinking about cleanout too. I might make an ash pan in the flat end of the FB under the CC. I will figure this out after I put the pieces together. I'm not sure about the tires yet. I plan on setting the trailer up level on jack stands until I get the smoker built. Then I will try to simulate the weight of the other stuff in the proper location. I can then use a piece of pipe on jack stands placed under the trailer frame as a pivot point to play around with proper axle placement so this thing pulls like it is supposed to. I may be over thinking that a bit! If it is close to the tires after that, I can always use some sort of heat shield.

    The way I have it laid out in the drawings, everything is accessible from the ground. The deck is just for a place to tie down ice chests and stuff. I will build an enclosure for the water tank and pump as well as the water heater under the sink. It will be interesting to see just how close to the drawings it works out in the end.

    Well I have not even started yet and I already have a setback. I go home tomorrow, and my wife has to have a root canal done Wednesday. With an 11 week old baby girl at home, I just hope to go get the pieces I already located and bring them to my house before I have to come back to work next Tuesday. I tried to tell her that I could take care of that tooth with a bottle of whiskey, channellocks, and my cordless drill so I cold spend that money on my build. I don't know why, but she didn't think that was a good idea.
  11. fagesbp

    fagesbp Smoking Fanatic

    You forgot the JB Weld filling. That woulda sealed the deal lol

    I'm going to look around on a few sites n see what's the advantage of having the fb iset into the cc. I know it can cause a hot spot at that end of the rf plate that some people use a deflector plate to cover.
  12. fagesbp,

    I would check with the gas suppliers in your area. I see you are in south La, but that covers a lot of ground. I passed by the one in Kentwood the other day and noticed a bunch of rusty tanks out back with red spray paint markings on them. I am not sure if they are for sale, but you could try looking at those places for your tank.

    Mounting the firebox the way you described was my original idea too. After reading a lot on here and laying it out on the trailer in my head, I changed it. There is only one way to find out.  how it will work. Just gotta make some sparks fly and see how it turns out.

    The hot spot is why I plan to leave the bottom of the CC intact and sticking into the firebox. Trying to keep the heat from being directly on the RF plate while the firebox is under it may be a challange.
    Last edited: Jan 7, 2013
  13. fagesbp

    fagesbp Smoking Fanatic

    I'm a long ways from Kentwood. I'm close to Lafayette.
  14. I was not able to get my materials together to start this past week home, it rained every day. Hopefull when I get home...

    I do have a couple questions though. Can I weld the firebox to the trailer frame or should I leave some spacing? How high would be good for the bottom cooking rack? The best I can figure mine will be 40" to 42" off the ground. I'm 6'1" so reaching it is fine, but will that we hard to work with?
  15. bruno994

    bruno994 Master of the Pit

    Weld the firebox to the frame of the trailer.  It really ties the whole thing together.  You can either butt it up to the last beam on the trailer or build it inboard, where the frame attaches to the sides of the firebox and not the back side.  Either way, the added strength is a plus.  As far as grate height, I want to say mine is around 36", the higher it is, the harder it is to reach the back of the grate, but if thats' where it's going to fall on yours, that may just have to be where it is.  Pull out (slides) grates or stationary? 
  16. Thanks, I was thinking along the same line on the firebox. I am just not sure if that repeated heat would weaken the trailer. My firebox will be round and I can set it between two of the cross members on the trailer. If I go all the way down and weld it to the trailer I can get my cooking grate below 40" which I think would be better. The bottom of the firebox would still be 8" or so off the ground. The grates will be pull out. That makes it a lot easier no matter how high they are.
  17. fagesbp

    fagesbp Smoking Fanatic

    Will the heat of the firebox transfer into the trailer and cause a problem?
  18. bruno994

    bruno994 Master of the Pit

    I wouldn't think so.  Mine is butted up to a 1/4 x 3 x 3 piece of angle that I added as a cross member support on the old boat trailer I used and it seems to be holding up great after 9 months and 20 cooks or so on it. 

    I think my firebox is about 9" off the ground and haven't hit it on anything yet while pulling it all over the area. 
  19. Well I finally got the biggest pieces home to get started. I have to clean the trailer off, remove deck and rail. Then I will cut the tank ank start mounting it up. I filled the bottles for the torch. Now I need to find some time to get started. I have been cutting up a big oak that needed to be cut down in the pasture. I will need some fuel for the smoker so I figured this was a good time. When I get that done, I will start on the build.
    I will be moving the axle. It also needs to be flipped and put on top of the springs to get it lower.
  20. I had a few minutes this evening to get the trailer stripped down. I need to get a washing tip for the torch to get the rest cleaned off.

Share This Page