32" build in Calgary, AB - pompeii neapolitan

[IH123]

I today, cut enough dome brick cuts to complete the full 3rd course , and also prepared the arch legs by cutting the top brick of the arch leg to the required angle. I did not mortar any bricks today but will do next week, I chose to construct the inner arch curve, only after the dome reaches 3rd-4th course where they can meet, to have a clear view of how it has to be (and will use the trammel to mark the inner and outer cuts on arch curve while using full brick to bridge between arch and dome). picture from today:

[david s]

Be sure to place some wedges underneath your timber arch former, so when removed it will drop and facilitate easy removal without disturbing the arch.

[UtahBeehiver]

Plus one on Dave's comment, 3/8 - 1/2" is a good release wedge size.

[IH123]

I have to cut my inner arch curve voussoir brick to allow combustion gas to swirl upwards on exit, so all smoke can be directed to the flue gallery as soon as possible without having to allow velocity to shoot it forward towards the mouth, this may require a bit of padding to my arch work form on top, which I can do with additional shims, as the arch work form was designed for flat cut (I made it before considering the aerodynamics of smoke) :

[david s]

You shouldn't really need this because the velocity of the smoke once the flue is drawing well will leave the sharper angle better than a rounded one. The corollary is the transom of a speed boat where the sharp angle performs better than a rounded one once the velocity increases a bit. "Duck tail" car designs work on the same principle. All ovens will smoke a bit at start up, until the flue warms sufficiently to create draw.
I once had the experience of operating my mobile oven at a market where the stall-holder next to me was selling hand knitted wares like baby booties. I was so worried about the smoke causing issues for her goods, particularly at start up. I discovered by starting a tiny fire and adding really small amounts of wood to progressively build the fire, that it is possible to do a completely smokeless firing.

[Giovanni Rossi]

One additional comment on the arch form. With the top open, it's possible some mortar may squeeze into that space effectively locking the form in place, even with a shim. If that happens, you don't want to force it free. Shouldn't be an issue for you as it looks like your assembly can be dismantled from either side. This is more a caution for other builders when designing their form.

[IH123]

I completed today the full of course#3, I think I am using thicker mortar than intended, while I am aiming 1/8" its ending up more, likely because the stones start curving with the dome. I hope where dome meets arch legs is not very bad.I did not set up the arch work form yet, just have it in place for easy storage. I just realized while looking at the pictures that I had handful of bricks not staggered, its because I buttered a bunch and was on a tight time , will fix it on next course for sure.

next, I plan to cut lost of dome brick cuts enough for 2 more courses and the inner arch cuts, then build them. photos from today:

[IH123]

I today, built course#4, excluding the connection to the inner arch.I am yet to cut the inner arch voussoirs - have first to make the arch work form deeper, increase it from 4.5" to about 8" so to support the intersecting bricks while dry fitting, I only cut just one with the full 9" length yet to trim the dome part and cut remaining ones. pictures from today's build:

[IH123]

I today finished cutting the inner arch bricks, the most difficult cut on 10" wet saw was to cut the wedge on the 9" long brick, I end up doing close to wrong cuts but it worked. while I used a wood rod with exact length to draw the contour over the arch bricks, I end up having what I had in my drawing (same dimensions like what drawing concluded). I used a simple cut that dome bricks would need extra cut when they meet the arch on an angle, couldn't pre-cut the arch to match the landing dome brick exactly. next, I will put inner arch work form in final position, over shims then top it with parchment paper, center it and level it, and then build and mortar the arch bricks. here are pictures from my work:

[IH123]

here is the inner arch pictures, its built now:

[IH123]

I removed the inner arch work form, and it was easy because of the parchment paper under the work form and above it. One issue I found is that my work form did not have a base plate (top plate cap) to hold the mortar at the bottom of the arch bricks so it flowed free fall, the parchment paper did not hold the mortar. I have for the other arches, to use aluminum foil or put on the work form a thin board as the inner part of the arch brick (would trim the thickness from the arch radius to keep it dimensional correct) will have at least 1/8" mortar thickness (I do not let inner brick faces touch because the mortar has no strength when its too thin, I rather leave the mortar between 3mm and 9mm all over to obtain the adhesion at the full cross section area of the brick joint.

I used a small trowel and hit the mortar dripping with the edge of the trowel and it was easy to break the about 1/2" mortar at the line. I will later smooth the surfaces with mortar after grinding where necessary using grinding block stone, I also need to grind the arch face where the door will touch to make it in same plane all over the arch opening.

Here are pictures after removing the inner arch work form: