My first 80Gal RF build... This is going to be a blast!

Discussion in 'Reverse Flow' started by alaska, Sep 9, 2013.

  1. alaska

    alaska Meat Mopper

    Its time to give this a whirl and I hope everyone shares their opinion, preferably prior to my squeezing the trigger or sparking the torch. My plan is to build an 80 gallon RF using this air tank as the CC. I also want to make the fire box in a square fashion as opposed to cutting an end off this tank.


    The tank says champion oil less on the side and it is a verticle model. What I plan to do is make the firebox square and have it attach on the left hand side. What thickness of metal should I make the FB out of? Why do some people make a frame out of square stock then skin it, is that necessary? Could someone assist me with a drawing of some type so I can really ask question by referencing the drawing?

    Measurments

    Circumference of tank 77.5 inches

    Length not including ends 35 inches
     
  2. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Alaska, evening....  some folks build the FB....  add 1x2 on edge.... stuff 2" rock wool in for insulation... skin the outside...  stuff rockwool into the tube also... 1/4" for inside FB.. 1/8 for outside....  you could fill the space with sand also...  don't plan on moving it when done.... 
     
  3. sqwib

    sqwib Smoking Guru OTBS Member

    Alaska... look in my signature... there's a few links to my build.
    Hopefully a few photos can help
    There's also a pit calculator link.
     
    Last edited: Sep 9, 2013
  4. alaska

    alaska Meat Mopper

    I may need to do that if the weather causes problems like some are describing.
     
  5. alaska

    alaska Meat Mopper


    Here is the tank that I plan to use. I loaded a few numbers in these two calculators and .....? 

    SQWIBs Calculator

    CC - 165021.72 Cu. In

    FB - 38.03 inches

    Daves Calculator

    CC - 18480 Cu. In

    FB - 6160.00 Cu. In

    I plan on swinging by the local Steel Shop to price out the metal for the FB so could someone give me an idea on what size you come up with along with the recommended thickness of the metal? 

    Thanks 
     
  6. Alaska,morning,for the firebox my preference would be at least 1/4" thickness,and a grate for the fire,so you wont burn it out on the bottom,my calculations from the size you gave were

    cc- 165021.72 cu in

    fb- 55007.24 cu in

    for a square firebox these were my measurements,you will have to deceide what size you want the firebox

    a 50"h x 50"w x 24" length will give you almost the same size firebox at 109.1%

    An undersized firebox will require frequent fueling and may not adequately heat the cook chamber. A slightly oversized firebox is preferable.

    Firebox Dimensiare)

    Firebox Dimensions (Round)

    Calculations

    Height

    40

    inches

    Width

    35

    inches

    Length

    40

    inches

    Diameter

    inches

    Length

    inches

    Specified
    Firebox Size

    56000.00

    cubic in.

    Recommended
    Firebox Size

    (1/3 of cook chamber)

    55007.24

    cubic in.

    Size Differential

    101.8%
     
  7. I based those numbers on a cylinder-type cook chamber,dave omak helped me with a lot of questions,and a few of the other guys as well,there is a lot of good info to help you along the way,im no expert by any means,but will try to help,thanks danny
     
  8. alaska

    alaska Meat Mopper

    I was looking at another build and the person is using a 115 gallon tank and his FB is 25 X 24 X 18 In saying this why would my FB need to be 50 X 50 X 24. this seems like a big difference in size.
     
  9. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    SQWIBs Calculator

    CC - 165021.72 Cu. In

    FB - 38.03 inches

    Daves Calculator

    CC - 18480 Cu. In

    FB - 6160.00 Cu. In

    ( 80 gallon / 7.48 )  X  1728 =  18,480 cubic inches.....   

    How did the other calculator come up with  165,022 cubic inches..  

    6160 cu. in. for the FB is correct....  20 x 20 x 16 = 6,400 cu. in.     

    Something is amiss.....   recheck stuff.....   If you need someone to help, I'm here....    
     
  10. alaska

    alaska Meat Mopper

    Dave.... Thanks for taking a look at the numbers! I was reading some other post and saw many opinions regarding making your firebox larger to keep from having to load it more often. As you know I'm here in Alaska and the temperatures will be extremely cold. I intend to use this RF every time I get a chance regardless of the weather.
    1. What are your thoughts on increasing the size of the FB to provide for a longer burn?
    2. By having the tank that I have for this build, insulating it would be a problem. If I were to insulate the FB would that assist me in any way?
    3. I pulled up the Circle Calculator and came up with the following numbers with the tank I'm using. Did I do this correctly? 
    Radius 12.32

    Segment Height ED 4.73

    Chord AB 19.409

    Apothem OE 7.59

    Central Angle 103.94

    Arc AB 22.35

    Circumference 77.409

    Segment Area 64.018

    Triangle Area 73.656

    Sector Area 137.67

    Total Circle Area 476.84

    Can I get some input on a 2 door vs 1 door Cooking Chamber.      Is it dependent on what I plan to cook/smoke?

    Thanks everyone in advance for your feedback.... Alaska AKA Jerome      
     
  11. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

     
    Last edited: Sep 12, 2013
  12. thanks dave for checking,i didn't think those numbers sounded right ,but that's what the calculator had,
     
  13. sqwib

    sqwib Smoking Guru OTBS Member

    Dave can you check the calculator I have in my signature and see whats up. If it's inaccurate or out of date let me know and I'll update

    Thanks
     
  14. sqwib

    sqwib Smoking Guru OTBS Member

    thats what I got on the Pit Calc 20x20x16=6,400

     
  15. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    My computer doesn't have the software to open it or get it to work.....   I tried.....     Dave
     
  16. sqwib

    sqwib Smoking Guru OTBS Member

    did you dowmload it first then try?
     
  17. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member


    My puter says I need the original installation source...  Software came with this machine....  I don't have the orig. source...   



    Just checked software updates..... AOK....
     
    Last edited: Sep 12, 2013
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    Last edited: Oct 16, 2013
  19. alaska

    alaska Meat Mopper

    Good morning everyone..... Dave, SQWIB and Black, I appreciate your taking a look at my numbers. I got my hands on some metal a few days ago, it was an old sluice box! Here are the measurements 1/4 in thick, 18 in sides, 38 in bottom and 18 ft long.....Think it was worth $25??

    Q -- What parts do you guys recommend I use this for?

    Q -- Dave... You mentioned I could make the FB even larger so the 20 X 20 X 16 that you came up with should only be the smallest I should make it, is this correct?

    Q -- Cutting the CC Door.... There was post dealing with warping the metal. Some recommend using a grinder, plasma cutter, torch, sawzaw..... I would not use a torch but would a plasma cutter not provide the best cut?

    Q -- How do you determine the size of your air vents on the FB door. 

     
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    Last edited: Oct 16, 2013

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