curious

[bowhunter35]

im new here and i am about to start my 2nd smoker build. my first one wasnt too great so im looking for some advise on what to do with this one. it will be a reverse flow design. see the firebox on the first one i think was too small. is there a simple equasion to tell what size firebox is adequate for my chamber? i have a 125 gallon tank. no cuts have been made yet. (note the word yet) any advise and help will be greatly appreciated. awesome site by the way! look forward to interacting with yawl.                                 uncle duckie

 

[nybbq]

Try this link.  http://webpages.charter.net/tomchism/BBQ CALC Forms/BBQ Smoker Calculators.htm   Looks like you fill in the info and it will tell you the size needed.

 

[sunman76]

yep if you use the calculator it will work out well.

can't wait to see the start...

 

[ribwizzard]

Ok,  I would be glad to help with firebox design ( my favorite part of the build) and I would not make any cuts on the tank until the firebox is built.

What problems do you have with your first build that you hope to correct on this one?

Also, will this be free standing or mounted on a trailer or wheels?

Will you be using wood or charcoal?

 

[jabbo]

That calculator is nice and as a back up reference, here is another calculator that I like to use, as well as, a circle calculator.  Between the three of them, you should be spot on perfect with this build.  Let us know if you need anything else.

http://www.1728.org/circsect.htm

http://feldoncentral.com/bbqcalculator2.html

 

[bowhunter35]

thanks for the calculator i think i figured it all out. my cooking chamber  measurements are exactly 63" long x21" tallx 21" wide, now if i did the math correctly i will need a 21"x 21"x 21" (or somewhere around there) firebox. it will be mounted on a trailor (which i have yet to have purchased" chimney should be somewhere around 4" diameter pipe about 4' long mounted about 8" from the very top of the smoke chamber on the side. hopefully it will all work out. and i will be using hickory and pecan wood to cook with. and i took another look at the tank and it is just 120 gallons (not125)

 

[bowhunter35]

i figured id modify an old used boat trailer for the mobility. or any suggestions? i am doing this on a tight budget so this project will take me awhile to finish.

 

[jarjarchef]

i figured id modify an old used boat trailer for the mobility. or any suggestions? i am doing this on a tight budget so this project will take me awhile to finish.

Welcome to SMF..

I am extremely slowly working on a trailer build........one day I will get to start the metal cutting and working part......but I am using an old 19' bass boat trailer.....going to work out very well, just a couple areas to look at if you are going to use one....most things are obvious to someone who does these things, but some were a surprise to me. I am by no means an expert on this type of thing, so my father in law has been giving me the hold you by the hand treatment and the looks that go along with it.......

1- rust. Mine is an old trailer and looks like was used in salt water a couple times. So I have a small area to repair. They used box tubing and there was no drain hole for the water, so it just sat and rusted a hole. But there was some surface rust, so I have been sandblasting all of the old paint and rust off to put new primer and paint on it.

2- Axels and bearings, Because of the in and out of water. Make sure they are in real good shape. I have taken the bearings completely out and replacing them and new buddy bearings.

3- Depending on the trailer design. May need some adjusting of the axel mounts for balancing. My cross beams are also in a "V" shape, so will need to be creative on smoker and any box mounts.

Bottom line for me, the price was right....FREE......well I have to take a bit of ribbing from father in law, but I can take it...

 

[jabbo]

Sounds like you have put those calculators to good use.  I have not crunched the numbers but they seem about right.  One exception is the Chimney.  I would shorten it to below 40" if possible.  Obviously you will need a slightly larger pipe, but I think it would help with the draft.  Second, and this is my personal opinion, I would lower the chimney to either even with or below the lowest grate.  There is a difference of opinion on this but I think it helps with the draft and even heating.  I love to use pecan.  It is always my go to wood, although, lately I have been enjoying apple.  Can't wait to watch it come together.  

 

[jabbo]

I went back and used your numbers and the chimney should be 36" above the cooker.  So you might want to mount that 4" pipe 12" down instead of just 8".  Other than that I think you are golden!!

 

[bowhunter35]

sweet. thanks for the advise. Now, im at the point where i need to mount the firebox how high should i mount the thing on the side of the smoke chamber? my firebox will be 21"x21"x21". if im not mistaken, it should be 1/3 from the bottom of the chamber, right? sorry about the questions, i want to build this right in case i ever want to sell it.

 

[jabbo]

Most guys place the FB about 1/4 to 1/3, of it's length, under or into the tank.  So basically your FB will sit 5 to 7 inches into the tank.  If the end of the cooker is flat, meaning you cut the round end off of the tank and replaced it with plate steel, then I would just mount it on the end.  As far as how high, there is a little debate.  Personally, I would mount it as low as possible.  Since heat likes to rise it allows for a more natural flow.  The area under the RF plate should be 1.5 times the area of the opening in the FB.  So the RF plate will be a little higher than the box.  The circle calculator I gave you can help you figure that part out.  If you have trouble let us know.  The more questions you ask, the more you will learn so don't apologize for that.

 

[bowhunter35]

ok man. i appreciate the advise. i stripped the tank down to bare metal today, so hopefully start cutting into it tomorrow. i think im just going to leave the curved end attached because i want all the smoking area i can get out of it.i have noted and adjusted the blueprints accordingly to yhe suggestions i have recieved on here.will post pics of the build when the smoker is finally done. and im ready to mount it onto the trailer. again, thank you all for the tips and advise.

 

[jabbo]

No problem.  That is what places like this are for.  The only thing we take in payment is pics of the build and that sweet Q-view!!

 

[ribwizzard]

Just some quick input on firebox placement; imagine where the end of your racks will be on that end and draw a straight line down. Thats where the firebox should start. Basically, do not have the top of the firebox under your cooking racks, but just about as close as you can. You dont want the greese from the drippings hitting the top of the firebox, you want them going into the reverse flow plate/ drip pan. Also, I recomend putting a plate inside the top of the firebox, with about 1/2 inch air gap between it and the top of the firebox . This would keep it from heating up the firebox end of the reverse flow plate as much and give more even temp across the reverse flow plate. Also will keep from burning the paint off of the top of the firebox.  If im not clear, let me know and I'll try to post a drawing to explain it better.

 

[ribwizzard]

Kind of like this, dotted lines would represent where the cooking grates would sit. I like the reverse flow plate to sit level with the top of the firebox on the inside of the chamber, thats why I recommend adding the 2nd plate under it, to keep the heat at that end more even. Im sure other builders have done different ways of handleing this, but to me, this is simple and also serves multi purpose.  You could also move the firebox further out, but you will end up burning more fuel from the heat loss.

 

[ribwizzard]

Also, when fiquring your opening, consider that by sloping your reverse flow plate as in the above drawing will also even out the temp. better. so the lowest part of the plate will be the smallest opening, and the one you want to be most concerned with.

 

[bowhunter35]

ok man thanks ill have to keep that in mind

 

[bowhunter35]

jabbo,i must be stuck on stoopid. what is q-view?

 

[jabbo]

Q-View is the pictures of the culmination of all of your hard work.  It is the pictures of your new cooker and the tasty stuff inside of it.  It's the view of the BB-Q!!!