Checking my math (actually checking to see if I used Feldons calculator correctly)

[rickgi]

Hello all, I have been reading here for some time and had a few questions.  I am new to welding and had struggled to teach myself for years with a Clarke 110 welder.  I had some extra funds and Miller had a sale and I bought the 211 autoset.  This helped greatly and I was able to see what I was doing wrong and where I needed to adjust.  I was given an old tank that has an inside diameter of 20" and is roughly 60" long depending on the rounded ends.  It has 5/16ths walls and I found a couple of 5/16ths 4x8 sheets of plate for $100.  I have most of the steel and an old trailer to put everything on.  I still have some challenges such as lifting it all but do have a small tractor with a FEL.  I used the Feldon's calculator and came up with 50.65 square inches of firebox to cooker opening.  I multiplied that by 1.5 and came up with 75.97 for the RF adjustment.  My 100% firebox size (100.8) is 18.5" cube.  I used the circle calculator to come up with a 6' segment height.  I was struggling to understand that calculator so I just adjusted the segment height until I got to around 77 ish square inches in opening with an 18.33" cross section. I haven't got to the air intakes or the stack height yet but wanted to check the math so far.  As long as I keep my opening to the correct size can I enlarge my fire box? This is not going to be a build thread just at the planning stage. Still have to address cutting everything accurately and maybe getting a decent plasma cutter.

Thanks,

Rick

 

[daveomak]

You are on the correct track....  Make the FB a bit wider than the RF plate for ease in fitment....  Larger FB is just fine... 5-6" below the fire grate for ash collection works well....  cut into the tank past the welds for ease in fitment...  Cut the main CC door AFTER you weld up the FB to the CC...  May help in reducing the warping of the CC....

Angle grinder and cut off wheels work well, not as fast as plasma but a lot cheaper..  for door seals, you can use thin sheet metal...  20-24 ga. mild steel works or 1/16" flat bar X 1" or 1.25"...   Weld on the door seals from the inside, so they look good, by drilling the doors or notching them with the grinder...

 

[rickgi]

Thanks Dave, I was hoping you would chime in.  After reading this forum for over a year I have watched you patiently answer questions over and over, your willingness to help is a testament to your character.  That is good that the firebox can be bigger, the ash box was exactly why I wanted it a little taller.  I appreciate that you anticipated some future questions and your advice.

 

[daveomak]

You are welcome....   The best plan for building a smoker is to "envision" the build when done....  what operations will be happening....  are the doors in the right place....  where will I stack the wood... where is the beer opener....  and use it while you are sitting in a comfy chair trying to build this smoker in your mind...

I used that exact system when I built my charter boat...   placing hydraulics, wiring, water lines, radar, sonar, heaters, tanks..   drew it all out with dimensions and walked through every scenario to try and avoid problems in the future...

Having a door open the wrong direction can be a PITA...   having ash buildup need cleaning every 2 hours can be a PITA....    having the smoker door too high makes it difficult for some folks to open...