20" Pipe RF Smoker

Discussion in 'Reverse Flow' started by geothermal, Jul 17, 2014.

  1. geothermal

    geothermal Smoke Blower

     Couple of questions:

      In the drawing on the right, I'm not sure I understand what "Divide Areas 80-20 / 90-10" means.

    According to Feldon's calculator if I size my firebox at 100% it calls for almost  4 openings 1.5" wide and 3" high.

    Would that be 3 of them at the bottom and one of them at the top? Or should I change the calculator to the actual size of the FB and use those dimensions to size the intake openings? That comes out to almost 5 - 2"X3" openings. So would that be 3 on the bottom and two on the top?
    Last edited: Aug 4, 2014
  2. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    80/20 ... 90/10 is the approximate ratios for the air intakes..... bottom inlet 80/90 % of the calculated air inlets and 10/20% for the upper air inlets.... it's not that critical.... just ball park....

    If the calculator calls for 4 openings 3 x 1.5 .... that is 18 sq. inches... I would go with 3 sq. inches on the upper and 15 sq. inches on the lower air inlet.... or something close..... 1 each 2x2 on the upper and 4 each 2 x 2 on the lower..... that 20 sq. inches... close enough for pulled pork....
  3. geothermal

    geothermal Smoke Blower

    Made some progress on the FB Door over that past few days.

    Cut this 1 1/4" X 3/16 angle with my Milwaukee Metal circular saw every inch. Then bent it around the door plate while it was all secured to the FB.

    Put wood shims all around the inside of the angle and tack welded each seam.

    Angle frame welded and ground. Door panel drilled for blind welding.

    Use 1" X 1/4" angle inside the perimeter of the FB. Same  cuts every inch.

    FB door blind welded and set on FB

    Inside angle welded and ground.

    Cut out intake vents and vent covers with plasma cutter. Closed position.

    Open position. I put 2 on the top just for fun and my FB door needed a face. Next I'll weld on some tabs to hold the plates in place.

    Last edited: Aug 10, 2014
  4. lendecatural

    lendecatural Smoking Fanatic

    The angle bends turned out really nice! I wish I was that good with stick welding, it's been too many years since I've done much of it. I'm really good at getting sticks stuck... [​IMG]   Love the "Happy Face" vents on the door, very nice touch.
  5. geothermal

    geothermal Smoke Blower

    As a lot of us did, I learned to stick weld in High School, long before mig came about. It's been a few years (like 43 years), but I'm getting better. Lots of practice on this project. Sold my mig welder last year when I moved. Wish I had kept it, but will get another one some day when I have a shop to work in. I had a 30' X 40' shop when I moved. Now I'm doing this in the driveway.
  6. geothermal

    geothermal Smoke Blower

    Got the FB almost finished. Not sure how the latches will be under heat.

    After the first failed hing, these were a re-fab that work.

    Got the smoking rack done.

    Inside of FB Door.

    Next will be the 4" smoke stack. I want to find a 4" coupling to weld to the plenum so I can remove the 4" stack in case I have to transport the smoker in my trailor.
    Last edited: Aug 14, 2014
  7. lendecatural

    lendecatural Smoking Fanatic

    Is the 4" going to be pipe or tubing? If you use pipe, you can get a socket weld coupling and only weld one side.
  8. geothermal

    geothermal Smoke Blower

    Yes, it's going to be 4" pipe. Thanks for the tip. Never heard of that before. I'll have to try and find one. Wow! Just found one at Granger for $93. Ouch!
    Last edited: Aug 15, 2014
  9. lendecatural

    lendecatural Smoking Fanatic

    Yes, Grainger is usually high, check a pipe supply house. Other option is to cut the pipe and tack a short piece of 4" tube inside. Should be a fairly loose fit since schedule 10 4" really has an ID of 4.250" and you should be able to get the tubing at an automotive exhaust system shop. I made a pipe to tube adapter by cutting a very short piece of schedule 10, split it, cut a little off of the end, and made a sleeve to take up the .250 so it fit the pipe ID good enough to TIG weld. I was going to hose but in your case it could work with a little grinding to get a better fit.
    Last edited: Aug 15, 2014
  10. geothermal

    geothermal Smoke Blower

    Thanks again Len. I'll be off to the steel yard to see what I can find. Made some progress today on the back wheels. My vision is starting to take shape.

  11. lendecatural

    lendecatural Smoking Fanatic

    You ARE going to stick an old tractor seat on top of that firebox.....[​IMG]  Very cool!
    solaryellow likes this.
  12. geothermal

    geothermal Smoke Blower

    You mean like this Len? Of course I am, and it wouldn't be complete without a steering wheel that will open the CC Door.

    I call it the HOT SEAT!

    Last edited: Aug 17, 2014
    jesse happ and solaryellow like this.
  13. solaryellow

    solaryellow Limited Mod Group Lead

    Love it! :biggrin:
  14. lendecatural

    lendecatural Smoking Fanatic

    That's off the chain! That will draw a crowd where ever you go!   [​IMG]  
  15. This build just went from really cool to totally awesome! Can't wait to see what's next!
  16. geothermal

    geothermal Smoke Blower

    Got to the steel yard Monday and picked up some 4" x 1/4" pipe for the smoke stack and front wheel attachment. The 4" id pipe is 4 1/2" od. They had some 4 5/8 id x 3/16 pipe that I bought to use in place of the Socket Weld Coupling like Len suggested. A little pricy at $26/ft but I only needed a foot.  It will be a little loose at the smoke stack, but I think I can put some fire box gasket rope down inside at the bottom of the 4 5/8 coupling to at least seal it off good and then some high temp silicone around the top. Then I'll be able to remove the stack when I have to transport the smoker in my enclosed trailer. Stay tuned for more pictures.
    Last edited: Aug 20, 2014
  17. wolfman1955

    wolfman1955 Master of the Pit

    This is the best build thread I've seen on here in a long time!!! Love the tractor theme!! What brand you going to go with on the paint scheme, Deare, Farmall, Massey?
    Just a thought, you may want to incorparate some sort of leveling system in your front wheel mounting brackets, something like a jack stand.
    Last edited: Aug 20, 2014
  18. lendecatural

    lendecatural Smoking Fanatic

    0.062 all around isn't much of a gap, get it all welded up and you may find it's a good slip fit. It doesn't have to be a tight fit like the firebox intake, that hot air wants the hell out of the CC.
  19. geothermal

    geothermal Smoke Blower

    Thanks Wolfman,

      I think I'm going for the rusty old "Steam Punk" look. Not sure if I'm even going to paint it yet. Yes, the front end is going to be a challenge. I was hoping to work on that today, but the weather isn't cooperating. Good idea on the jack stands. I'll have to see how stable it is with what I have in mind.
  20. geothermal

    geothermal Smoke Blower

    Thanks again Len. The fit isn't too bad. Got it put together last night. Here are some pictures.


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