Building my first pit I am excited- 20" pipe backyard smoker

Discussion in 'Reverse Flow' started by phat rico, Apr 12, 2013.

  1. Thank God for this forum! I was about to build my pit all wrong! I should be getting my plasma cutter within the next two weeks. So I am close to starting my build. I ran through the calculators that I found here and this is what I can up with it. 

    20" Dia pipe x 36" long = 11304 in^2

    Firebox 16"x16"x18" = 4608 in^3 ~ 122%

    4" chimney pipe 18.5" long

    FB to CC  opening 4" segment w/ 1" dam

    RF plate 6" segment = 79.267 in^2

    RF plate 18 1/3" w x 31.5 long leaving 4.5" gap at end =82.485  in^2

    RF plate 1/4" slope 


    My questions:

    1. Is a 1/4" slope good enough for the RF plate to drain? 

    2. When I cut out my single large door I was planning on leaving 2.5" each side making it a 31" door.  Is that good? 

    3. how big of a dam should I have at the end of the RF plate? Is 2" good?

    I got most of the stuff I need for the build except the smoke stack.  I need go to a scrap yard b/c brand new cost too much. 

     
    Last edited: Oct 24, 2013
  2. question

    1: yes a 1/4" is enough. if it if going to be trailer mounted, you can put it in level if you want. most likely you won't be on level ground.

    2: if you are going to use slide out grates and i recommend that. you lose 5" of grate. i would go all the way to the end. i have done both.

    3: 2" will be plenty

    4: i know you didn't ask question 4 but i have to answer it for the group. keep the pics coming and ask questions. everyone here will be happy to help.

    happy smoken.

    David

    welcome to the group.
     
  3. 1. Yes

    2. Yes

    3. Yes

    You should be able to buy a 2' piece of 4" pipe for $20 or so new if you can't find any at the scrap yard.. I bought 4' of 6" for less than $50. Like themule said post pics of your progress. I know I like to look at builds to see if someone else came up with an idea that I might use some variation of.
     
  4. Looking forward to watching your build.  If you need info please don't hesitate to ask on this forum.  I enjoy watching the questions and answers...never know may find an idea to jack for my next build.  LOL
     
  5. bruno994

    bruno994 Master of the Pit

    Welcome to the forum from another Texas member...these guys have you lined out, so there is no need to answer already answered questions.  Please keep us posted as your build progresses. 
     
     
  6. Thanks for your answers.  I will post pictures as I build! 
    Mule, Are you suggesting I have a full length door of 36"? That would seem difficult to seal. Could having full length grates hender the reverse flow? 
     
  7. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    I'm in.........   [​IMG]  .....    I love a smoker build....     

    With the 1" dam at the FB opening, you could increase the segment height to 4 1/2" with no adverse affect....  The segment height for the RF  plate does not have to be adjusted...  it will be perfect....   A full length cooking grate will help force the heat under it which is a very good idea...  the holes in the cooking grate will allow for great air flow.....    I like you design...   

    If you cut the circle plates for each end, and inset them into the pipe, that will help with the door seal if you are cutting the door full length.... they don't have to be inset more than a 1/4"....  

    Dave
     
  8. if you have 1/4" end caps that gives you 1/4" to use bar stock to overlap. makes a pretty good seal. the reverse flow plate does not know how big the door is, unless you tell it!

    happy smoken.

    david
     
  9. So I did some welding last week end.  First started on the legs. Got them cut and tried to drill holes for 1/2" rods but didnt get them to line up.  I just welded them in the back and filled the hole. 




    Picked these wheels up from grainger


    Legs welded


    Welded to my 20" pipe


     It ended up pretty level


     This is 1x1 angle sitting on top of 1.25" tubing.  I am going to have to use the the 1/8 flat bar to fill in the gap. Next time I will fab this better. 

    Next I need to start on my drain, RF plate and cut my door.


    For my drain can I use square tubing welded to pipe?  I bought the pipe before I knew what i was doing. It is too short I and dont want to buy another one. 


    I could pull off the weld.  but I am concerned about grease and crud getting stuck in the pipe.


     See the ledge?  Is that a problem?  
     
  10. bruno994

    bruno994 Master of the Pit

    Not enough to worry about.
     
  11. When you cap those ends, it will be easier to not have the stand welded to it.

    Dont try to cut a circle to fit inside the pipe for the caps, cut it slightly larger than the pipe and weld it on the end and take your grinder to trim the excess.

    Id leave close to 1.5 to 2 inches at each end of the door.

    As far as the grate going the whole width, remember, the smoke should come around the reverse flow plate and go over the meat, not under it.  So having the grate there is fine, but if you stack food up at that end it will hinder the proper air flow.

    I might get a little feedback on the "over the meat" comment, but trust me, its better that the smoke fall down unto than rise up through.  Another advantage of a reverse flow plate
     
  12. Thanks for the feedback. 

    I bought end caps that are 20" so they match the OD of the pipe. It will be tough to weld upside down.  I have never done that before. I thought it would get too heavy for me to lift later so I mounted it. I could tip it on the end if it gets too hard to weld. 
     
  13. Yip it on end.  Your welds will be far better.  This IS going to be seen.  Flapper disks for 4" grinder work wondes to clean up a weld.  Good start
     
  14. Dont try to weld it upside down.  What I do is bevel the end of the pipe, lay the end cap plate on a table flat, stand the pipe upright on top of the plate ( makes it easy to center), then run the bead all the way around.  Lay the pipe horizontal and smooth the end out with a 36 grit flapper disc.  as I roll the pipe.  Your really only grinding the weld bead and the end cap, following the contour of the pipe. This way it has no seam and looks like one solid piece.   I find this to be easier than setting the plate inside of the pipe and welding it and a lot faster as well. And you dont have to go on the backside and weld the inside , as long as you bevel the pipe good and "push " the bead into the plate.  When I set the pipe on the plate, I take four tooth picks as well and give it just a little gap, and I get good burn through with .045 wire, and pushing the bead into the plate leaves no gap on the backside or inside.

    Its just easier to handle everything and more enjoyable than any other way i've tried.

    Im doing a set today and will take pics if I dont forget.
     
  15. here, like this. Did these this morning.

    [​IMG]
     
  16. [​IMG]
     
  17. Got four welded, but just got these two grinded , Dress them up a little more with 60 grit flapper wheel before paint.

    [​IMG]
     
  18. I like the way it gives it a cleaner look and lets me round the edge with out being worried about a thin spot.  Ive been giving some thought about pressing out the center of the end cap, giving them a dished out look, just have not took the time to try it yet.
     
  19. Anyway, Im going to go jump in the pool and cool off.  Good luck , which ever way you decide to do them.
     
  20.  This looks great.  I will go ahead and tip it. 
     

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