1 metre first smoker

Discussion in 'Reverse Flow' started by steelewilly, May 24, 2016.

  1. steelewilly

    steelewilly Newbie

    Hey there everyone.
    I'm new to this forum and the art of building smokers. I am from Australia and these types of smokers are pretty well non existent here.
    I have been studying these forums for the last 2 evenings and think ive got it figured out. I have a lot of welding experience for a young fella and will aim to sell these if all goes to plan.

    Here is what ive got for the first build:
    2 bottom halves of 45kg nitrogen tanks and a shit load of 6mm plate for a fire box and smoke baffle plate.

    I have included my measurements of tank in the pictures. I'll be joining both halves of tanks together and cutting/hinging door in the morning. If anyone can offer assistance on smoke flow calculations i would appreciate it.
    Thanks guys i look forard to sharing and learning with the rest of you.

    Btw here is a pot belly fire i built last week.
  2. steelewilly

    steelewilly Newbie

    Anyone know why my photos dont show up?
  3. steelewilly

    steelewilly Newbie

  4. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

  5. steelewilly

    steelewilly Newbie

    Hey dave i read it last night. I can't understand why there is no mention of inlet size on firebox as that should determine every size afterwards regardless of firebox size. Unless i missed that bit.
  6. daveomak

    daveomak Smoking Guru OTBS Member SMF Premier Member

    Diameter X Diameter X 0.7854 X Length = Volume in cubic inches / 231 = Volume in gallons

    Volume in cubic inches X 0.004 = FB/CC opening in square inches

    Volume in cubic inches X 0.004 = Area under the RF plate in square inches

    Volume in cubic inches X 0.004 = Area required at the end of the RF plate in square inches

    Volume in cubic inches X 0.33 = minimum volume of the Fire Box

    The above areas are necessary for great air/heat/smoke flow.... using less may cause an overheated FB.... Narrow / Long CC may require an increase in those numbers due to increased surface area friction to volume... Wide/Fat Short CC may use smaller numbers due to reduced surface area friction to volume...

    Volume in cubic inches X 0.001 = FB air inlets in square inches...

    Recommended upper and lower air inlets... Upper air inlet directly across from the FB/CC opening to facilitate moving heat from the FB to the CC, and insuring good air flow through the CC.. The lower air inlet should be situated at or below the fuel grate.... The two air inlets can share the designated square inches of opening.... approx. 20% upper and 80% lower...

    Does that answer your question.....
  7. Hey Steelewilly,

    Welcome from another Aussie  [​IMG]​    Where about's are you from? 

    You will have to make a choice on which calculator you follow as opposed to taking some understanding of one and applying it with another. The one Dave has supplied has built a lot of happy smokers and I'm currently using that for my build    http://www.smokingmeatforums.com/t/245332/new-patio-build-from-australia  

    Just some advice, you should convert all your measurements from mm to inches as that way the other members can help you with your calcs.

  8. steelewilly

    steelewilly Newbie

    Ok, ive done the calculations. I have attached a photo of them. I am sure something is not right. Most of the photos ive seen on this sight shows the opening between fb/cc as being a smaller hole than the area underneath the rf plate. Can someone confirm this.
    Hey bazza, im in and around canberra. How about yourself?

    Thanks, will
  9. Hey Will,

    Yeah I'm on the other side in Perth. Went to Canberra once. Bit cold for me!

    You need to work through the entire calculator including the circle calculator bit as this will tell you important things like the width of the BP (baffle plate) which is shown as "chord AB". It also shows how high you need to cut into your tank "segment height ED" to achieve your required FB / CC opening which in this case is 25.822 sq inches.

    You will see with the calculator I have got this figure (or close to) in the "segment area" which now matches your required FB / CC opening.

    So the calculator is telling us you need to cut up 3.1 inches on your tank. It also tells us that your BP needs to be 11.862 wide.

    The advice I have been given on builds like ours (smaller) is that we need to exaggerate the numbers a bit. In the circle calculator try increasing the Segment height ED to 3.5 which will give you a wider BP (chord AB) and a slightly larger FB / CC opening. Or maybe Dave can advise on how much you should exaggerate this by?

    Last edited: May 25, 2016
  10. steelewilly

    steelewilly Newbie

    Thanks bazza,
    Im at the pub at the moment. I'll have a look at this when i get home. Looks like the information i was lacking. Ive just been making assumptions based on the air flow in my homemade pot belly which flows perfectly. The grandfather also gave me some old books on how to build wood stoves which look like they will have a lot of useful info in them. Heres what i did this afternoon.
    Looks like ive cut the breather hole a little too high. Didnt want to weld it fully closed so i cut it out to prevent an explosion. Cut it where i thought firebox would join roughly.

  11. smokin monkey

    smokin monkey Master of the Pit Group Lead OTBS Member SMF Premier Member

    Will be watching this build.
  12. socalcooker

    socalcooker Meat Mopper

    Is that tank stainless? It almost looks like it's galvanized, which you would not want to use for cooking.

  13. steelewilly

    steelewilly Newbie

    Last edited: Jun 19, 2016
  14. steelewilly

    steelewilly Newbie

    Last edited: Jun 19, 2016
  15. socalcooker

    socalcooker Meat Mopper

    Sorry, I didn't realize they weren't galvanized on the inside. I've been welding a long time and I despise welding anything galvanized. So I've never bothered to look at the inside of a galvanized tank. And no a painted tank wouldn't bother me, but paint burns off at a very low temp.

  16. steelewilly

    steelewilly Newbie

    All good
    Last edited: Jun 19, 2016
  17. l'm taking the gal off mine with pool acid

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