Drum Calculations

Discussion in 'Charcoal Smokers' started by suprfast, May 1, 2009.

  1. suprfast

    suprfast Meat Mopper

    I was putting my drum together and decided to give everyone a math point of view on calcuations.
    Stay tuned on another thread for my drum build(x2)

    First thing you want to do is take the diameter of the drum. Remember if you measure the inside of the drum you need to add for thickness of the drum walls twice.
    I came out to ≈22.75" I rouned most of my measurements so this might have a slight variance to others.
    Next you find the circumference of the drum

    Now that you have the circumference you will need to divide by three

    If you mark all the way around the drum 23.81(or just round to 23.75 since the tape measure will have this marking) you will have three almost exactly spaced holes for the intakes. The same calcuations can be used for the racks if you use three screws or divide by 4 if you use 4.

    Yea, im a nerd that loves to eat. Anyone needs any help making calcuations harder than basic algerbra let me know.

    Ill add later the formula to use so i can have a perfect 8 1/2" holes in the lid.

  2. travcoman45

    travcoman45 Master of the Pit OTBS Member

    Thats some right fine cipherin yall done there.

    I kept it simple an scratched it all out on a chunk a wood with a pencil. Came out ta within a 16th of an inch which be more en accurate fer a drum smoker.

    Hey, I ain't no math wizard, keep it simple, but ifin it works fer you, bravo! When ya gonna post the drum pics?[​IMG]

    I found usin mommas seamstress tape measure sure makes measurin them round thins lots simpler!
  3. suprfast

    suprfast Meat Mopper

    Its simple enough to just go all the way around and divide by three too[​IMG].

    Cooking surface area on a drum with weber 22.5" grate.
  4. billbo

    billbo Master of the Pit OTBS Member

    I spaced mine out 23 5/8 apart and that seemed to work well for me. Trav hit it on the head too. Anybody doing a drum should steal their wive's seamstress tape. If you don't have one I would highly recommend you invest in one, I'm sure they are not that expensive and make the job sooooo much easier.
  5. suprfast

    suprfast Meat Mopper

    i picked one up at walmart for 1.70
  6. ddave

    ddave Master of the Pit OTBS Member SMF Premier Member

    If you are real picky you can use this layout that I found on another forum.

    You can increase the size of the attached file. For full size of 21.8" square resize it to 2093 pixels square. It doesn't really matter if the resolution gets grainy. You can still see the lines. I printed a copy on the plotter at work but I imagine if you have a Kinko's close by you could get them to print it for you. Cut out the circle and lay it on top of the drum and mark away.

    Not really a big deal for dividing the drum into thirds but it is very helpful for the 8 lid holes if you go that way.


  7. hog warden

    hog warden Smoking Fanatic

    I wasn't that precise in doing mine. The pork butts don't seem to mind. Anyway, I put this together after finishing my UDS. Mostly relates to appearance:
  8. trapper

    trapper Smoke Blower

    Here is my idea for the holes in the lid. I promise it is faster. Hang the lid up on a tree. Get a 12ga with improved cylinder choke and one round of OOO buckshot. At a distance of about 8 yards shoot the lid. The shell has about 10 pellets and at 8 yards all of them should hit the 22" lid. The holes will be around 3/8" in diameter. Shouldn't take but a second and I bet the pork butt doesn't care.
  9. billbo

    billbo Master of the Pit OTBS Member

    Good one trapper! I just measured in 3" from the outside rim and cut the drum into an immaginary pizza in my mids eye and drilled away. Came out OK.
  10. ddave

    ddave Master of the Pit OTBS Member SMF Premier Member

    No, the pork butts don't seem to mind . . . but the ribs are a finicky bunch. [​IMG]

    Hey, I didn't say you HAD to use it. Just offering it up in case someone wants to use it. [​IMG]

  11. pinkmeat

    pinkmeat Smoking Fanatic

    Luckily I had a smaller bullet type smoker with the same three screw grate support design. I laid the weber grate on top, and taped the areas where the three bolts were lined up. I then held the weber grate inside my drum and marked the holes, then measured up from the bottom equal distance, then drilled and mounted everything. Worked well.

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