36" Pompeii Build in the desert

[jim lofaro]

I removed the front arch form and the arch has held so far. I am seeing 3 measurements I can use to build in the serpentine arch:

• The distance from TDC to a given place on the right and left serpentine bricks.
• The level between the right and left serpentine bricks.
• The angle of the serpentine bricks.

I am thinking the level and the distance from TDC are the more important of the measurements. Any thoughts/recommendations?

[JRPizza]

Jim, I built mine without a form, but have seen folks use a curved plywood one too. The most important measurement is making sure you don't close the opening too much to not get the square inches you need to vent the oven, and also the footprint you need to seat your adapter.
David is right about the design not lending itself to tying in the corners, but I don't think mine is going anywhere unless it dilates at the bottom and if that happens I'm not sure the top of the arch would have made any difference. One thing you have to think through is how you are going to sandwich the serpentine arch in with the protruding keystone you have in the front. I like the look, but my smooth curve made it a little easier to put the "saddle" bricks I have sitting on top of the arches. You can probably do something with a notch at the bottom to go over the keystone and it will look very nice. Once you figure that out you can make your chimney with the traditional tied in ends and it should help with the stability a little.

[jim lofaro]

I screwed up. My serpentine arch has a 4 inch opening instead of a six inch opening. Can I notch an inch or so from the inner part of the serpentine brick to achieve a 6 inch opening? Any other methods to correct this problem? BTW I am going with a 6 inch duravent.

[jim lofaro]

I guess i could always set back the next serpentine brick a bit to give a stepped serpentine arch.

[JRPizza]

I don't know how big your opening is below the unmortared brick, but other than cutting a more severe angle to try to correct you are stuck with either using your stepped method or doing some disassembly. On second thought, if you go the stepped route you could always trim the brick lengthwise on the thin end to eliminate the visual external step.

[jim lofaro]

Thanks JR. The opening below the unmortared brick is 6 inches. Let me give this a bit of a think.

[david s]

I screwed up. My serpentine arch has a 4 inch opening instead of a six inch opening. Can I notch an inch or so from the inner part of the serpentine brick to achieve a 6 inch opening? Any other methods to correct this problem? BTW I am going with a 6 inch duravent.

Yes you can notch it out a bit, but don’t worry too much. If there is some restriction just before the pipe it simply acts like a Venturi and the smoke will accelerate there. You have to restrict it a lot (more than 30% of the area), to reduce the draw, which comes primarily from the diameter and secondly from the height of the pipe. The draw comes from the rising column of hot gas in the pipe.
A 6””” inch diam pipe is the correct size for ovens up to 36””” inch int diam.

[jim lofaro]

Thanks David S. So I did a bit of an inner notch on the right serpentine brick and seems to give enough room for my pretend 6 inch pipe. My plan is to go with a 2 foot pipe and cap with spark arrestor. Sound about right?

[david s]

It is more important for a smoother inner surface which gives a smooth flow of gasses than how it looks on the outside.Similar principle as headers on a car exhaust vs clunky old manifold.

[jim lofaro]

Point taken David. My plan is to put in a 6 inch diameter plastic plant pot and fill around with mortar.

[jim lofaro]

The serpentine arch is up. Happy with it so far, even the notch. Looks like the next steps deal with the front and back bricks for the arch?

[WarEagle90]

The serpentine arch looks good, Jim. I’m interested to see how you close in the front and back gap between the two halves of the serpentine.

[jim lofaro]

Thanks Dan. I also am interested to see where I land on the closure. I cut 2 blocks for the front. The right one I tapered to follow the outer contour of the serpentine block. The left one I left square. I cannot decide which works best for me at this point. Think I will cut the next run and see. Any thoughts?

[JRPizza]

This is one of those things I had not considered till I got there. I ended up putting an angle on my uppermost serpentine brick so I would be rectangular at the top, but my opening was much wider than yours is. I had to bring my chimney bricks in to meet the "saddle" bricks, where you need to angle the saddle bricks to meet the chimney. You just need to play around with some configurations to see what looks best. I had to do a bunch of "honey, come look at this" before I was done

[jim lofaro]

LOL on the "Honey, come look..." statement. That is where i am now. Attached is the latest configuration following the outer contours of the serpentine arch. Any problems with this configuration??