Author Topic: Fire Pit Oven  (Read 4187 times)

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Offline wahoo88

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  • Location: Maryland
Re: Fire Pit Oven
« Reply #25 on: June 06, 2013, 09:00:58 PM »
Ok, I've drawn out what may be the final product.  The right stovepipe wall is cutaway for easy viewing.

Materials are as follows:
Tan/Gold: fire bricks, split
Red: Unglazed quarry tile
Wavy silver: steel (angle irons)
Dark grey: miscellaneous metal, not aluminum
Orange: shows where the oven is open to the fire below
Black: Stovepipe

Scott, is this exactly what you had in mind?
I may change the roof to UQT to cut down on costs.

Thanks.
Dan


scott123

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Re: Fire Pit Oven
« Reply #26 on: June 07, 2013, 02:39:46 AM »
18" diameter x 5" high stove pipe doesn't exist.   If it did, this would be WAY easier.  That's for the most part, what you're creating- what you're piecing your small strips of cut stove pipe into. The only difference is that your finished 'pipe' won't be a full circle, but, rather, a U shape with an opening in the front where you launch the pizza.

5" high stove pipe doesn't exist either.  You might find some sort of 5" adapter or extender, but I wouldn't waste your time looking for it.  Here's what you want:

http://www.homedepot.com/p/t/202907227?productId=202907227#.UbFdEmoub0k

This is 6", you may want 8".  It depends on the wall height you go with.  Earlier you spoke about tucking the wall between the brick and angle iron, but now I see that you have the wall sitting on the brick in your diagram.

If you sit the wall on the brick, and go with 5" walls, with .5" quarry tiles, that's 4.5" to the ceiling. It's tight, but think that's what I'd go with.  You don't want to cramp the launch, but, at the same time, in bottom heat scenarios, the ceiling, for proper heat balance, should be as close to the hearth as possible.

If you tuck the wall between the firebrick and angle iron, that means you have to add the 1.25" thickness of the bricks to get the same 4.5" dome height making for a wall height of 6.25". There's one consideration with a tuck, though.  If you're at angle iron level on the sides when it comes time to run the wall across the back the two angle iron pieces in the middle will block it.  What I'm think you can do, though, is terminate each wall run at the back middle.

I've been thinking a lot about my bolt post/film projector idea. First off, I'm renaming it my wicker approach.  The angle iron lip that the firebrick sits on has enough room for thin bolts to run up through it while still allowing enough space for the brick to sit on. Beyond putting bolts at the termination points, you can put bolts every few inches (maybe 4") along the path of the wall and just zig and zag the wall through them like a wicker basket.  At the end, you can loop the wall around the post and fold it back and slide it into the previous post.

One of the strengths of a wicker approach is that, should the seam of the stove pipe be either riveted or spot welded (a distinct possibility), rather than clasped, and can't easily be reclasped, you can leave the wall sections separate as you thread them through the posts, overlapping them at the ends.  You might even position your bolts/posts so that those are where the ceiling angle iron crosses/sits on, allowing the posts to take the brunt of the ceiling weight rather than the sheet metal from the pipe. The bolts will be the weight bearers, while the pipe strips are just air entrapment.

The only potential tricky part to this is the flexibility of the stove pipe.  Flashing would probably wend it's way through the posts and double back beautifully, but stove pipe might not be quite as flexible- at least maybe not for the double back part.

Other than the decision as to how to approach the wall, your diagram looks right. The only things I would change would be, if you are going to sit the u shaped wall on firebrick, without posts either in the middle or at the end, then you'll need to add right angles at the top of the U/front of the oven and corresponding bricks for the lateral pieces to sit on (see my original drawing).  You could, in theory, fold the walls inward, but then you'd lose precious lateral real estate on the pizza size you can make. Right now, you can do an 18" pie. You might not do that all the time, but you want to try it at least once.

Speaking of real estate. The diagram has your quarry tiles arrange in a rectangle that looks about 12 x 22.  They don't need to extend all the way to the front of the bricks, but you definitely want them as close as possible to each wall. The center pieces of 1/8" angle iron, when back to back, will give you 1/4" in the middle, so your quarry tiles should be 18.25" x 18.25"- a nice big target for 16" pies and just enough to squeeze an 18 in there.

I think you're clear on how to cut the stove pipe with tin snips, but, just in case you're not, here's a picture.  Btw, tin snips can make very sharp edges.  Use leather gloves and sand all your edges down. Oh, and I think this is obvious, but don't use the crimped area.
« Last Edit: June 07, 2013, 02:46:48 AM by scott123 »

scott123

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Re: Fire Pit Oven
« Reply #27 on: June 07, 2013, 02:58:15 AM »
I just noticed one other thing.  Beyond the wall, in the back of the oven, you want only one pair of bricks, not two. The angle iron should extend as if you had a second set of bricks, though, so you can slide the bricks out to add wood (remember the arrows?).  You can always add wood on the sides, depending on what metal you use to cover them, but, since you want the fire as far back as possible, feeding it from the back might not be a bad idea. Besides, moving a piece of metal might be more sketching than sliding a brick a few inches along an angle iron track. 

Offline wahoo88

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  • Location: Maryland
Re: Fire Pit Oven
« Reply #28 on: June 07, 2013, 10:39:11 AM »
Alright.  The stovepipe should just be able to snap securely together at the seams?  I'm worried that those joints might not be strong/flexible enough to 'weave' back and forth, especially if a seam happened to end up right at a turning point.

I just got lazy with the drawing in not covering the floor completely in UQT, but I'll put as much baking space as possible in.

I guess I should try to flatten the pipe sections before trying to weave them in by putting weights on it.

The outward stovepipe bend at the top/front of the oven is primarily to add rigidity; it isn't directly holding an angle iron and bricks, is it (and only applies if I rest the stovepipe on top of the bricks)?

Now most of the work is in sourcing the materials.  It may take a while for me to get out to all these places.

Thanks.
Dan

scott123

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Re: Fire Pit Oven
« Reply #29 on: June 07, 2013, 11:03:37 AM »
An 8" pipe will give you 25" long strips.  Depending on where you put your posts, you should be able to weave them in and out without connecting them.  The stove pipe seam also might be just a folded over edge that hooks another folded over edge. If that's the case, you might be able to squeeze the two lips together with a pliers for a sturdier joint.

I think we'll have a better idea of how to proceed once you obtain the stove pipe and see how it's connected, how rigid it is, and how well it flattens.

The outward stovepipe bend isn't holding bricks. It's just there to keep the wall stable.  If you weave, though, that bend isn't necessary.



 

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