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Ultimate 275 Gal.OIL TANK Smoker/Rotisserie/Grill

post #1 of 25
Thread Starter 

Import restrictions make bringing a ready made smoker trailer into Canada a hassle so will build my own and post my progress. I will keep a running tab of costs as I go along in a materials list and post pictures also  . NEW at this so will solicit your help often for ideas.

This Build must be able to multitask so here are the essentials followed by the build plan and the build.

---MUST HAVE......---Removable Rotisserie..........At least 3 cooking grates as slide in shelves that are removable so I can roast a pig when needed.----Trailer mounted with room for expansion...........RHS rear mounted firebox..........Charcoal wood baskets in the baffle plate to do duty as a Grill when needed.Metal cover when not in use...........Black pipe plumbing for gas with quick connect couplers for.....gas burner over fender  on other side for a fryer.....Quick connect gas at the rear to handle propane torch to light wood or charcoal....Plans bought from a link on this site for this very build! doing stuff to the plan as I scrounge for materials..........I ALREADY NEED HELP..................................... 

Questions...a) oil tank is concave on ends any ideas other than cut off and weld a flat piece to it? $$. b)should I have a Drain at the bottom? What size,where? Thanks guys


Edited by wonderwhy - 2/3/13 at 7:06pm
post #2 of 25

Cut the ends off and weld flat ends on it is the "norm" when you want a rotisserie.  


Yes, 100% need a drain on any big smoker.  


As for where? ...  I don't know how anyone else suggests you do it, but I got mine mounted and all that... then dumped about a cup of water in the middle of the tank.  I lowered the landing leg alittle and cut my 1 3/4 inch hole where the puddle was.  I used a 1.5" ID pipe because I already had a ball valve for it.   


Hope this helps.

post #3 of 25
Thread Starter 

Thanks bbq Bill, Makes perfect sense .Bet these suckers get heavy when done.. You got me thinking.My oil tank has a bung at the top that I can mount a drain to  Will flip the tank over and use the available two inch hole with ball valve as a huge drain.

I will however try the puddling trick first to see if I am on the mark or not if not will do exactly as you did start to finish (hope I get lucky).  I guess overthinking the concerns can and will get me into trouble.Thanks again.

Edited by wonderwhy - 2/3/13 at 7:00pm
post #4 of 25

Your welcome! Glad I could help!   I am just about to get mine buttoned up and ready to sand blast.  More pictures to come.


I would say, if you already have a suitable hole... use it!!  I am not a great welder and it took alot of welding and grinding to get mine to where it won't leak.

post #5 of 25
Thread Starter 
Thanks Bill . Winters here are severe so it dawned on me I might find a ready made fire box.from. a wood stove. Found a bunch on a local classified site . It's 18x18x30 flat sheet steel door with air dampers and even refractory brick in the bottom . Weighs maybe 150 lbs. this style of slow burning wood stove is common here and cheap mine was $50. No hinges or handles to buy and other than weld the stack opening shut ready to cut hole in the back and weld to the tank as soon as I get a stiffened plate made for tank side. Scrounging has gotten me 3 tanks today including a nice 72"x 36" round tank. All free. pictures soon I promise.
post #6 of 25

Very cool!! Cant wait to see it!

post #7 of 25
Thread Starter 



Here  is a picture of one of the fireboxes I bought today... They are plentiful in Canada and run from free to hundreds... This one had an asking of $125. they are all very negociable and one of mine was only $50. Should work fine on my oil tank build. Saves lots of work even has embossed front doors.The doors seal quite well also. Only need to cut off the chimmney flange and weld a patch and cut out the hole in the back and weld her to the oil tank.... couple hours max.

Edited by wonderwhy - 2/5/13 at 8:31pm
post #8 of 25

WOW! I wish I could find one!!!  I live in Florida and they are few and far between!  

post #9 of 25
Thread Starter 

 calculated the volume of the smallest of my stoves and come out at about 9200 cubic inches. I have three different sizes of oil tanks so will figure out the calculations as to cooking chamber size etc... If my understanding is right firebox should be mounted as low as it can vs the oil tank, , I am assuming the baffle plate should be at the same height as the top of the firebox. Again assuming this is to get a good airflow.A little planning here will help. I have purchased plans from this site but rather than do things blindly trying to understand the whys and whats of the build. By changing the firebox sizeI know I am throwing things off. Is a larger firebox have detrimental effects other than using more fuel.?

Will pickup a freebie oil tank this A.M.that is new never  used, It is identical to the 275 gal. tanks but much smaller will post pic later today and dimensions. and manufacturers  info plate details. This may be the CC  for the smaller of the  wood stoves I have.

QUESTION. How do I figure out the volume of a oval oil tank in cubic inches? I should know this but high school was 45 yrs ago. .Help

post #10 of 25

DaveOmak  gave me this site.  It is a calculator for building a smoker.  You can just enter the gallons of the tank rather than the dimensions.



Hope this helps!

post #11 of 25

Your 275 gallon cooking chamber is 63,525 cubic inches and your firebox should be at least 21,175 cubic inches.

post #12 of 25
Thread Starter 


Thanks Bill,

My wood stove is way off size wise for the 275 gallon so will use my 120 gallon instead. This size cooking chamber has a 99.3 % of firebox size using the calculator.. Spot on. I will learn from this one and am sure I will find this much more portable size very convenient. Might even make a good rental unit or for small smokes.Only 30 inches wide but height is  the same from what I can tell.but is narrower.... Has only had clean water in it to supply a concrete cutting saw. The crap on top is ice,grass and mud. from sitting upside down against a garage Will go with a single barn type door for simplicity in the build.Never have enough smokers I am told.Might have to add a little more air intake although have seen these stoves in action they can generate lots of heat when needed.But not sure how much draft I need to create.

post #13 of 25
Thread Starter 

calculator works great. Was funny to see how I was trying to calculate volume. Same calculations I was using to calculate asphalt needed to do a serpentine driveway. Gotta give my brain a break.

post #14 of 25

LOL!!!  Yep, the calculator is waayyyy easier!

post #15 of 25
Thread Starter 

 Thanks Calculator works great. I am discovering the more time I spend looking at the builds I am reminded how little I know. Would de making lots of mistakes but as I read or see via photos different builds it all begins to make sense. My little build will begin next week so will mock things up on my trailer to get a feel for it then search this site again for ideas. photos to follow after I dig out from 18 inches of snow on Friday The build portion is lots of fun and especially getting the components cheap.

LOCALLY everyone with wood burning stoves have had to convert to 2000 degrees  chimneys so the 1200 degree insulated units are usually free for the taking. Even the chimney caps do not interchange with  the 2000 degree units so free also.

post #16 of 25
Thread Starter 

Mods to the firebox wood burning stove. Will fabricate an ash drawer tray on one side also add an larger air intake on the bottom. Might have to actually make this box grew a little as I really like the idea of the insulated firebox bricks inside. Anyone with experience on the use of firebrick ? 

post #17 of 25

I am getting close to finishing my build. (lots of pictures on my profile)  

post #18 of 25
Thread Starter 







OK  Help!!!! my freebie 120 gallon oil tank now has a firebox and a skid made of angle iron to bolt to my trailer.

      Calculator has me running a 17 inch chimmey in 6 inch diameter. i have a piece 36 in. long that i mounted with 11 inches inside the CC and 25 outside. Is this chimmey too long?











post #19 of 25

Good to know thanks for the link

post #20 of 25
I really gotta get my a$$ in gear and start working on mine. The only thing holding me back is my garage isn't heated.
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