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  • Insulated RF cabinet

    Hi guys!

    I've finally started my first smoker build and decided to go with a reverse flow insulated cabinet design. I'm a bit further along in the build than this post so I'll recap what I was able to get done in about 3/4 days time in the first few posts.

    I struggled at first with whether I wanted a trailer or just a smaller unit for the house. In the end I compromised with unit for my house that I should be able to load into the truck if I need to bring it to the beach for the weekend or elsewhere. I figured I'd learn my lessons on this one and go all out for the trailer unit later. The overall size is 22.5"w x 22.5"d x 43"H and the cooking chamber will be roughly 18"w x 31"h x 18"d.

    I'm a construction superintendent so I come across extra material all the time and this time was no different. The iron workers on my site gave me bunch of stair pans left over from the project, they look to be 14ga or thicker. These have a nice bend on the ends forming a natural channel 1" deep which is perfect for holding insulation and makes a sound structural corner. They also gave me a 2'x2' piece of 1/4" plate I'm going to use for the firebox/ cooking chamber separation.

    From there I went out and bought a new welder... I haven't welded in about 16 years so don't expect miracles. I stopped by the iron yard and pulled a bunch of angle, channel, 1/8" plate, tube, 9ga. expanded metal and 14ga. sheet steel from the bargain barn.

    The concept was simple but it took me a while to visualize exactly how to build it. After a bunch of research and combing the internet I came up with a design I think will work. The idea is to have the firebox down low as usual and the right and left sides have a 1" chamber running up to the top with the exhaust down low in the cooking chamber.

    For insulation I'm using mineral wool at 1" thick on the sides, doors and bottom, 3" thick on the back and 2" or more on the roof. More on why I did that later... I assure you it's not scientific!

    Because I'm using the metal pans this smoker will be built more like a uni-body than the typical steel frame and shell. This caused me a lot of difficulties during the build and a ton of extra welding. I'm definitely going the traditional route next time.

    I do have a question for the smoker gurus out there. Since I'm bringing the smoke up both sides on the interior should I install the firebox intake on the door or can it be installed on one side? I had planned on a 2" ball valve down low and a 1" valve slightly higher, but the more I thought about it the more I keep thinking that will cause one side of the smoker to get hotter than the other. If it's better to put the intake on the door then I will most likely build a slide type intake with a brass set screw or knob that can tighten down to prevent accidental movement.
    Attached Files

  • #2
    Fugger’s gonna be heavy
    Center that firebox. What about the rear? Swinging fireboxes sound kinky... ;{)
    In God I trust- All others pay cash...
    Check out the Mad Hunky and products at https://madhunkymeats.com or https://www.facebook.com/MadHunkyMeats
    Lang 60D, The Beast, 18 and 22 WSM, Brinkmann Backroads trailer, Weber 22 Kettle, gutted MB burning watts

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    • #3
      Definitely going to be heavy, the 2x10 bench I built is starting to sag when I re-position her to weld. I would say she's well over 200lbs and the build is only about 66% complete. I'm starting to have real difficulty moving the beast around. I'm waiting on the wheels before I start to fab the door up because this thing will have to move to the ground once that much extra weight is introduced.

      On to more pictures of the build. As you can see I arranged the pans to butt together and welded them up. In this fashion the corners are reinforced and the center of the span is reinforced the long way. This also gives me a nice area to weld the inside skin to and really stiffens the whole assembly.

      The slow part of this all the grinding and removing the thick primer to be able to weld up the pans. I spent more than half a day grinding off paint and eventually I decided to do less grinding and use the primed surface for the outside skin. The only problem with that is I will have complete fill the joint with weld and grind that off for the finished paint.
      Attached Files

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      • #4
        Looking good! I need to stop by the local scrap yards and see what I can scrounge up

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        • #5
          In today's installment I get into the actual build. Right off the bat I discovered a problem with my original design. I'm using 2"x4" tube steel for the chimney, so the back was to be a 2" insulated cavity. Because of the bends in the pan and where they join up I ended up having to push the cavity to 3" to accommodate. More insulation is better, but less chamber size is not.

          I got three sides welded up square, insulated and then welded on the inner skin, 14ga sheet steel. After, I started the bottom panel where I made a mistake that I didn't discover until just the other day when I installed the c-channel for the gasket. I built the bottom just like all the other sides, I coped the bends to fit nicely into the other panels. Great fit actually, everything was working out perfect. What I didn't think about was where the front bend was I really wanted to put the c-channel to create the 1" depth for insulation. This would have provided a smooth plane on the bottom, making ash removal easy. Now I have a 1" lip there which will take some work to clear ashes.

          All in all not to bad to this point, more thinking than actual work. Lots of my wife getting mad for ignoring her and trying to get some time in with the kids in between work and the build.

          Up next, more lessons learned on this build!
          Attached Files

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          • #6
            Wow! That puppy is gonna be a BEAST!!


            Drinks well with others



            ~ P4 ~

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            • #7
              Thanks Hawg!

              Anymore ideas on what I could do with the intake? Best setup? I have an offset style smoker now so I'm not sure what to expect from the vertical cabinets. I really wanted to keep it simple but I have a feeling I will regret installing the valves. I don't want them to stick way off the front of the smoker.

              Also, should I be installing a grease drain of some sort? I could pitch the plate steel to one corner but I'm not sure that it's necessary with this design.

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              • #8
                A simple "slide" plate for intake works good. You have the room. A drain is also nice for that occasional clean out for water

                Comment


                • #9
                  Yesterday I had the day off and I got a bunch done for the inner cooking chamber.

                  I got the c-channels fitted and welded on to hold the gasket. They stick out about 1/8" from the skin of the smoker to allow for a tight seal.

                  I ended up installing 1/8" steel on the bottom of the firebox instead of 14ga. for longevity. I decided to go with a grease drain, so I machined the 1/4" plate and welded on the flange to the underside and created a small bowl in the plate with my grinder. I also, pitched the whole plate to one corner to encourage the grease to flow in the direction.

                  Last thing I was able to do was get the inner chamber skin on and welded up. A pretty good day but I'm having real trouble getting into the corners on the interior to weld up. I might look into one of those flexible mig guns for the future.

                  I'm on hold until my wheels show up. This thing is officially to heavy for me to flip around.
                  Attached Files

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                  • #10
                    Originally posted by fasttruck860 View Post
                    Also, should I be installing a grease drain of some sort? I could pitch the plate steel to one corner but I'm not sure that it's necessary with this design.
                    Yer gonna want a drain..especially as you have the “lip” at the bottom of the firebox. You DO need to wash ‘em out once in a while..and you don’t want water sitting in there.
                    In God I trust- All others pay cash...
                    Check out the Mad Hunky and products at https://madhunkymeats.com or https://www.facebook.com/MadHunkyMeats
                    Lang 60D, The Beast, 18 and 22 WSM, Brinkmann Backroads trailer, Weber 22 Kettle, gutted MB burning watts

                    Comment


                    • #11
                      Got quite a bit done over the last week on the smoker. Unfortunately the memory card in the phone died so I lost a bunch of pictures.


                      I insulated the back cavity 3" thick, welded on the outer skin and spot welded the middle to the chimney. I also got the top on with a minimum 2" of insulation, going to 4" thick at the peak of the roof. All the outer skin and inner walls are finally fully welded on and water tight. Now for hours of grinding, I think I need upgrade to a new 7" grinder .



                      Now onto the doors. After mulling over my options for the firebox intake I decided to keep it simple with a slide for the door. I was going to do something complicated and special but at this point in the build my wife is getting really tired of me spending more time with the smoker than her. I'm also getting close enough to finishing that I can taste the meat .



                      I cut some 1"x1" tube steel to cap the ends and add additional bracing in the middle. Once that was done I cut a piece of 2" black steel and welded that in to allow for the install of a temperature gauge. For the firebox door I used 1"x2" tube for more structure and 1/4"x1" flat bar to build out the intake area.






                      I haven't finished welding the doors up but I started to get some warping in the cooking chamber door so I'm done for the day and will have to figure out how to fix that next time.

                      I'm hoping to finish the doors this week and grind all the joints smooth and prime. I have some more detailing to complete as well. I'm thinking of adding in a folding shelf on each side to hold plates and utensils.

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                      • #12
                        Perhaps some X bracing on the cook chamber doors...
                        In God I trust- All others pay cash...
                        Check out the Mad Hunky and products at https://madhunkymeats.com or https://www.facebook.com/MadHunkyMeats
                        Lang 60D, The Beast, 18 and 22 WSM, Brinkmann Backroads trailer, Weber 22 Kettle, gutted MB burning watts

                        Comment


                        • #13
                          ImageUploadedByTapatalk1474928064.881658.jpg
                          I'm just saying

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                          • #14
                            Lol I did say I haven't welded in about 16 years. Practice makes perfect so the next one I will have prettier welds.

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                            • #15
                              The end is finally in sight! I was able to straighten out the main door, but it will need some tweaking when I install the hinges. The firebox door is just about complete with a quick coat of paint to keep from rusting.



                              I made some brackets for the wheels out of 1/4" plate and built brackets for the dual purpose handle/ cooking utensil holder.



                              Once I was finally able to her standing upright I realized the way I bolted on the wheels wasn't going to work. The bolts have too much weight on them and are sagging because of the leverage of the wheels. Once I have everything else sorted out I'll go back and install a solid rod instead to prevent this. The whole unit is so damn heavy that is still pretty difficult to move around even with pneumatic tires.



                              Finally got the coal basket built and installed. Got the gasket in, the rack angles installed and the bullet hinges for the firebox door on. I should be done this week and I'm hoping to season and smoke by the end of the weekend.



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