Starting a build and have a few questions (pictures Added)(Q View now added)

Discussion in 'Reverse Flow' started by goldbarron, Sep 25, 2013.

  1. goldbarron

    goldbarron Newbie


    I am starting a build it is going to be a lot like a Lang 48" Patio.  The Lang has a fire box that is 18" x 18" and the calculator says that that is too small.  Is the Lang's firebox undersize or am I  missing something.

    I have a 24" x 48" 1/4 in steel plate rolled into a cylinder and the 24" end caps ready to start cutting and I am also wondering what a good distance from the end of the cylinder to the sart of the door?  Also I could use some guidence on the position of the door.  Is the door cut from on a clocl 9:00 o'clock to 12:00 o'clock or some orher  dimension.  I am sure that I will have more questions in the future but these seem to be the most pressing right now thanks for any help.

  2. I would not cut the door at 12. You will only lose 1/2" or less of vertical space if you come 2 or 3 inches lower on the tank surface to make the top cut. The bottom of the door can be lower than 9, or at least mine is. I figured the height of the RF plate and put the bottom of the door 3" above that so the grate could slide out and with the 1" tubing frames the top is 4" above the RF plate. If I remember correctly it is 2" measured on the tank surface below 9.
  3. goldbarron

    goldbarron Newbie


    Thanks for the information it will help alot when I layout the cut.  One other question is how far in from the ends of the cylinder should I cut the ends door?
  4. [​IMG]Hello, and Welcome from East Texas. This is a great site, lots of good information and great people.


    Keep us posted with plenty of pictures  !!!!!
  5. goldbarron

    goldbarron Newbie

    Started the build today, Ilifted the cc to see how long I wanted to make the legs.  I decided to make the legs 30" long with 5" casters at the bottom.

    In the above picture I am using the end plate to mark the end of the legs to match the contour of the CC.  After marking the I cut it with a metal cutting band saw and finished them with my knife grinder.  It is not welded yet so if I am doing something wrong let me know.
  6. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    GB, evening.....   Using a template sure takes the guess work out of stuff.....    Nice job....  

  7. Looking good, headed in the right direction.

  8. goldbarron

    goldbarron Newbie

    I am doing some reasearch and want to check on what I found our just to make sure I am on the right track.  I did a search on the fire box and found how to use the circle calculator and using Feldon's calculator I got the following information for a 24" diameter cook chamber.

    With a FB to CC opening needing to be 54.72 in sq and the area under the RF plate needing to be 1.5 times that I adjusted the circle calc. and found  my RF plate needs to be 5 3/4" high.  That would make The RF plate about

    20 1/2" wide.  Then the opening of the area at the end of the RF needing to be the same size as the FB/CC opening I would need to have about 3" between the end of my RF plate and the end of the CC.  If you can follow that does it sound close?

    Using the above information I would place the FB 6" up into the end plate.  Then if that is all right is there a rule of thumb on how far into the end of the CC the FB should be placed?

    Thanks for any help or suggeations on my questions.

  9. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    GB , Evening.....    I just did a drawing for Alaska....  Same size smoker... You did good on the numbers...    RW (RibWizzard) has experimented and found having the FB/CC opening the same as the exaggerated area under the RF plate, makes that area an extension of the FB....  Seems to be an improvement in the smoker...  

    Sooo... Under the RF plate 5.5" from the bottom of the smoker, make the FB/CC opening the same....    At the end of the RF plate, a gap of at least 5.5" to the end of the CC will reduce the friction loss....

    Exh.stack.... 4" ID 30" above the CC will work... 

    FB....  20x20x18 or larger...Larger preferred probably 20-30% or more will be fine and no adjustment in any of the other numbers is necessary...    

    FB/CC opening ... Feldon's 57.6 I think is for a standard SFB smoker and1.5 X's that for a RF smoker is necessary and for the RF plate...

    Then you will have little to no friction loss....   

    If I can be of help, I'm here....    Dave

    Original numbers to make final calculations....

    Link to BBQ Pit Calculator
  10. goldbarron

    goldbarron Newbie


    Thanks for the great information I will use it in my building process.  The one question I have is how far to set the FB into the CC.  In the pictures of the Lang Smokers I have looked at it looks about a quarer ot third of the length of the FB.

    Thanks again for the information and picture

  11. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    GB, It's not necessary to set the FB into the CC....  It does help with fuel efficiency and making the smoker package shorter and shortens the RF plate which saves a few bucks...   

  12. do not extend it farther than the end of where your cooking grate will be!

    And try to keep the center of the fire out from under the cooking chamber, ....something like this..

  13. alaska

    alaska Meat Mopper

    Hello from Alaska.... I enjoy your questions and the answers your receiving... Dave put the pencil to paper for me and I'm going to run with it.... I am confused about the Ribwizards comment regarding the placement of the FB... Not putting it too far into the CC... I will wait for feedback....
  14. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    I think RW was referring to the flames directly hitting the RF plate, if the FB was part of the CC and the top of the FB was part of the RF plate...  Then you would have a hot spot on the RF plate...

  15. Thats about right Dave, the top of any firebox will have a hot spot directly over the flames, keeping that hot spot outside of the cooking chamber will give you more even heat inside the chamber, but adding an extention to the firebox going under the chamber will transfer more heat into the chamber, allowing smaller fire and less fuel usage.  You can do the smae thing with a square firebox, but just keep your fire towards the door and away from the chamber. On #19 I built a fire grate with sloped angles that keeps the coals centered where I want them as they burn down. But I do wish I would had made the firebox deeper as in the drawing above.

  16. goldbarron

    goldbarron Newbie

    Dave and Ribwizzard,

    Thanks for the great information, now all I need is time to work on it.  When I bought my metal I took the measurements of the FB off the lang site and have the metal to make an 18 x18 FB I am thinking that I need to buy a piece of 2" wide 1/4 in metal and weld it on to the pieces to make it 20" x 20".  I would definitly be putting my poor welding skills in full view with that long of a straight weld. GB
  17. goldbarron

    goldbarron Newbie

    I finally got some time to get a little work done on the BBQ.  I needed to get some 1/4" X 2" metal to add to my FB parts that I had cut at the metal supplier.  I welded the back to get it to fit a 20" X 20"  FB.  I still need to add the pieces to the other parts.

    I also welded together some square tubing to make the base for the thing to sit on.  I hope that it is long enough to be stable.  GB

  18. alaska

    alaska Meat Mopper

    Nice looking plan...Are you planning on some braces to keep that legs from spreading out? Keep the photos rolling Im enjoying them.
  19. goldbarron

    goldbarron Newbie

    I was not planning on it.  If I get it attached to the CC with a good weld I should not need them.  I hope I might change my mind when I get the two attached.  If I do I will add them after they are put together so I have a little play to get it positioned right.

  20. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    GB, morning......    Trust us....   you will need bracing .....  Avoid a dangerous situation.... of the legs collapsing...   

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