Introduction: Large Rotisserie Pit BBQ
Once a year we gather for a Thanksgiving feast with 3 or 4 turkeys cooked on a spit. Last year we rented a mobile unit ($$) so this year I came up with plans for our own. It can easily be sized up or down for your needs.
The BBQ was built as a dry-fit project - no mortar was used. It's a lot easier to assemble and, if the location doesn't work out, it's move-able. Also, if a brick happens to crack from the heat, it's easily replaceable.
NOTE: I won't really be addressing the details of the rotisserie motor. Suffice it to say you'll need an old electric motor (from a furnace or a clothes-dryer) with a gear-box that can slow down the RPMs. Ours is an antique unit that turns the spit at about 1 revolution per minute. I imagine a combination of bicycle gears could be rigged up to do the same thing.
Step 1: NEEDS: Materials List
Note - These are the materials I used... I list them only as suggestions. With luck you'll have other materials hanging around that will work just as well!
FOR THE BBQ BODY:
25 - - - - - 8" x 8" x 16" standard blocks
15 - - - - - 8" x 8" x 16" cap blocks (or standard)
4 - - - - - - 8" x 8" x 8" half blocks
22 - - - - - 12" x 12" patio stones (optional)
4 to 8 - - -Wood/metal Stakes
1 - - - - - - Flagging tape or string
FOR THE PIT:
1 - - - - - -16' x 12" wide expanded steel (optional)
6 to 8 - - - 24" rebar pieces (optional)
2 to 3 - - - Cubic feet of sand or gravel
2 - - - - - - -4' x1.5" metal pipe
FOR THE TOP / LID:
1 - - - - - - Food-grade steel drum
1 - - - - - - 20' x 1.5" angle iron (bed frames are great)
1 - - - - - - Wooden hockey stick
4 - - - - - - 5" x 5/16" bolts (with nuts & washers)
2 - - - - - - 2' x 1/2" threaded rod (with nuts & washers)
1 - - - - - - 7' x 12" (1/8" thick) steel plate
1 - - - - - - High-heat flat-black BBQ spray paint
FOR THE GRILL (optional):
1 - - - - - - Expanded Steel 30" x 48"
2 - - - - - - 1" x 64" Steel Pipe
Step 2: NEEDS: Equipment List
- Long Level
- Short Level
- Safety Glasses
- Measuring Tape
- Old Chisel or Axe
- Permanent Marker
- Carpenters Square
- Hand-held Grinder
- Metal Cutting Discs
- Masonry Cutting Discs (optional)
- Wheel-barrow (optional)
- Friendly Welder Person
(OH, And don't forget an Axe for LOTS of Hardwood!)
Step 3: Size Is Everything
Using standard concrete blocks - aka "Cinder Blocks" - the design is easily scale-able. Make it any size you want. The blocks are found at most hardware stores (Home Depot, Lowes, etc.) but I was able to save money by buying "seconds" from a wholesale distributor at $2.00 apiece here in Ontario, Canada.
The standard block is usually sold as 8" x by 8" by 16". This is not quite true. The specs refer to a block in a completed wall WITH mortar. The block itself is actually closer to 7.5" x 7.5" x 15.5". I also chose blocks with squared / finished ends for the corners. I was happily surprised to find "cap" blocks for the top surfaces.
Please find my rudimentary blueprints attached.
Step 4: Location, Location, Location
We gave location quite a bit of thought before assembling the BBQ. Remember that it will be giving off a lot of smoke and heat once it's fired up. We chose a convenient spot that was a safe distance from trees and play areas. If you use an electric motor you will also want to be located near an outlet.
As this is a pit BBQ we had to consider tree roots. They are difficult to dig through(!) and also pose a fire hazard. The fire could get into the roots and smoulder underground for an extended time, making it's way back to the tree eventually. I suggest having buckets of water around when the BBQ is fired-up... just in case.
Step 5: A Good Foundation
FYI - concrete blocks are HEAVY. Each block weighs 40-50 lbs, so forty of them will weigh a lot! A solid foundation is absolutely critical. After leveling the ground we decided to first lay down 12" x 12" patio stones to help distribute the weight and keep the bricks from sliding into the hole.
We measured the area and used stakes with flagging tape to mark the outside perimeter of the patio stones. NOTE: It would have been wiser to wait until AFTER laying the patio stones before digging the one foot pit. We dug first and made the hole too large by mistake. Doh!
To keep the soil in place we used 12" strips of expanded metal held in place with 2 ft rebar stakes. We also added thin, flat rocks behind the metal screen - cause it just seemed like the right thing to do.
Step 6: Lay 'Em Down
Now you can lay the blocks tightly against each other, checking for level (and square) often. Many of our blocks had little bumps and "extra bits" that had to be teased off with a hammer & an old axe. Lay some of the 1st row blocks sideways to allow for air to feed the flames.
In some spots we needed "half blocks" to complete a row. In other areas we used "cap blocks" which have a finished surface over the holes (not solid top to bottom). They were almost the same cost and gave it a more polished look IMHO.
Step 7: Up, Up and Away
On top of the patio stones we put down 3 rows of cinder blocks. On one end of the 3rd row, we judiciously placed a half block to leave a gap for the spit to come through. Using supports (next step) the spit should come out just above, but not touching, the 2nd row of blocks.
After putting 2" of sand on the bottom of the pit we ended up with 25" height from ground to spit. This seemed adequate and the amount of cooking heat can ultimately be controlled by the size of fire and opening of the lid.
We also measured for a 1/2" hole to be drilled in the top row of blocks on either end (see photo). This is used to mount the hinge brackets on either side.
Step 8: Giving It Support
For the spit we used a 8 foot black steel pipe with a few holes drilled along the length. A gear was welded to one end. To support it we used 1.5" pipe and hammered it 24" into the ground at both ends of the BBQ. On the tops of these pipes we welded horizontal arms at the desired height, and "v" brackets to hold the rotating pipe.
We could have have simply supported a single rotisserie pipe but we wanted the option of adding other things later, such as a grill. For this we welded horizontal steel arms to the support pipe, and more "v" brackets to support additional pipes.
Note that we made the height adjustable by sliding two sizes of pipe inside one another. This will allow the grill to be lowered for traditional camp-fire cooking, or raised for warming pots and plates. We carefully drilled matching holes through the pipes so that a long pin or bolt can be inserted at various heights.
Step 9: Capping It Off
I don't weld, but thank goodness for friends who do. (Your the best Larry!) We used an old food-grade drum (cut in half length-wise), some scrounged bed-frame angle iron, and 1/2" threaded rod to whip up this hinged lid.
My advice would be to measure often here. We just barely managed to cover the length of the BBQ opening, but it worked! With some patience we made it square and then used a hockey-stick for a handle, spaced away from the BBQ with 5" bolts and copper pipe. Caution here because the handle can get a little toasty when there's a roaring fire.
Step 10: Other Details
A 'secret' feature of this BBQ is the adjustable warming plate. The steel drum wasn't wide enough front-to-back so we added a 12" wide steel plate on the back. This makes a great surface for keeping dishes & plates warm while dinner is cooking. It can be moved to allow for more or less smoke to escape too.
To make the lid rotate we welded 12" lengths of threaded rod to the back of the lid (on the angle iron bracing). This is then fed into vertical hinge brackets on the side of the cinder blocks and secured with bolts, allowing for a fully open bbq when needed.
Step 11: Tried by Fire
It probably goes without saying that no one wants to BBQ with toxic vapors floating around. For that reason, we had a really good & hot fire in the BBQ prior to using it for any kind of cooking. It burned off all the various finishes, though surprisingly, the exterior drum paint was hardly affected.
To protect the steel from rust I've been told to use "High-Heat" flat-black paint on the exterior surfaces. Other internal parts can be protected with repeated applications of Canola oil which has a higher smoke point than most other oils.
Step 12: Let's Eat Turkey!
And here's the finished product in use. We spear the turkeys length-wise and then use large steel 'nails' through holes in the spit to keep the meat from spinning freely. Wrap it all securely with stainless wire and foil, and even more wire, to keep it a tight-knit bundle of goodness.
Our 20 lbs birds took about 6 hours of cooking, removing the foil near the end for an hour of browning. Note that we sometimes supplement the fire with charcoal briquettes for a quick and long-lasting heat source.
After the turkeys and rotisserie are removed two more pipes can be laid down on the support arms and a grill placed on top to keep food warm.
That's how we did it... Now go try it yourself... Good luck!
Step 13: Other Resources
How Stuff Works: