Building a smoker...

[rapscallion]

This is my first post and ,my first build. I lookin for some input. Here is my info off the BBQ pit builder Calulator... Thanks!

Link to BBQ Pit Calculator

 

[so ms smoker]

  Looks like nyou have done your homework! Be sure to take pics and keep us posted!

   Mike

 

[rapscallion]

Thanks Mike. I will get pix up soon!!

 

[weedeater]

Rapscallion,  The calculator is definitely a good place to start.  I would suggest that you check the size of your tank with the calculator also by putting in the inside diameter and length assuming it is a traditional propane type tank.  I have found and seen on this site where the actual size of the tank is different from what people think.  Some times it has to do with the "useable volume" being less than the total volume.  Post plenty of pics as you go and you will get lots of help from some very knowledgable experts on the site.  Good luck in the build. Joe

 

[rapscallion]

Here are the tanks. I was originally thinking of making one, by cutting the bottoms off and welding them together.... But decided to make a small one first. Then the BIG one.

 

[kaizerscall]

I say cut the bottom off and weld together! Why not go big? Do you have the room?

 

[rapscallion]

I like your style with cutting and making one big one...

 

[daveomak]

Rap, morning..... What are the actual dimensions of your tank ??  I have some ideas that could be of help before you make the first cut...  

Dave

 

[rapscallion]

The actual dimension of the tank are 30" dia x 48" long. 120lb porpane tank.. It has soaked for 3 weeks with water & bleach and I have flushed it out numerous times.It is ready to cut! I think...

 

[daveomak]

Rap, evening.... Weedeater covered the first important part...   Get accurate measurements....  Guesstimate the ID as best you can... using probably 1/4" wall thickness of the tank... 

Next, plug in numbers in this circle calculator for the Firebox to CookChamber opening, and the RF plate height and width.....    If you need help with the calculators I will be glad to help....

Also, if you are building a side fire box type smoker, or reverse flow.....     making the FireBox a little wider than the Reverse Flow plate will simplify the build dramatically..... Make sense ???   I'm here....   Dave

          Circle Calc

 

[rapscallion]

Hi Dave, Thanks for the info... Now, I'm really confused! The tanks is a 120 gals (So told). It's total O.D. is 46.25", I.D. is 45.75". Dia. is 30" O.D., 29.5" I.D.. My trouble lies with the end caps. The middle of the tank (cylinder part) 20,513.035 cu.in.. From the weld seem to the ends is 7.875" I.D. with a Dia. of 29.5" I.D. But, it's a compound radius. What kind of tolerence am I allowed? Can I build the firebox on the larger side to be safe? Then where does that put me with Firebox to Chamber and the RF plate??? Confused!

On the bright side this is really cool learning how much goes into one of these smokers!! Experience is knowedge and, I appreciate your time and patience...

Thanks!

Rap

 

[rapscallion]

IMAG1351.jpg

• rapscallion
• May 23, 2013

 

[rapscallion]

IMAG1340.jpg

• rapscallion
• May 23, 2013

 

[rapscallion]

The next big question is can I cut out the door and start prepping the inside? Any special tricks for that??

 

[daveomak]

Rap, evening....  Here are some numbers you can use for your smoker build...  I suggest drawing it to scale to see how stuff fits... Firebox and how to fit it up.... RF plate...  Where it's going....    food grates... and the door....

Since the RF plate needs to be about 25" wide, I suggest making the Firebox 26-27" wide for easy fit up....    In Feldon's calc, I used 30" but that could be changed.....    Need any help, I'm here and so is everyone else....  

Dave

Sorry, some stuff had to be edited.... I will PM you with the info if you wish.... 

 

[rasimmo]

The pics do make that easier to explain. Good idea.

Rapscallion,

I agree with Dave on drawing the build to scale before starting anything. It helps to get your head around where everything will go and how it fits. It's nice to have when you are building too so you can check real quick and make sure you are putting it together correctly and cutting everything at the right place. On the end cap volume you asked about, mine was the same. I assumed the volume was 2/3 what it would have been if it was straight and capped flat. Figure the volume of a 7.875"x29.5" cylinder and figure 2/3 of that. I'm not sure if this is exactly right, but it was the best guess I could come up with on mine.

 

[daveomak]

I just added 5" to each end of the straight section of the smoker for the heck of it.....  Close enough...  40" length and 30" diameter...  anyway you choose to estimate the Cook Chamber volume is good....   I suppose there is some way to calculate a compound curve but it's way beyond me....     When I got here I was a dummy...I learned quite a bit...I am still a dummy...only smarter..

Dave

 

[okiedave]

If you can accurately measure the true volume (fill it with water and measure how much it takes, for example), you can subtract the (calculated) volume of the straight-walled barrel section; the remaining volume will be the sum of the two endcaps.  Divide by two, and you have the volume of each endcap.

Sometimes measurement is easier than calculation.

 

[rapscallion]

Is it a bad thing to build the firebox a little bigger than whats called for?

 

[weedeater]

Is it a bad thing to build the firebox a little bigger than whats called for?

Not in my book.  Much better to be bigger than to be too small.  Nothing says you have to max out the fire in the box but it is a pain to have to keep stoking the fire because you don't have enough output.