Pdx 42" update

[Gulf]

I'm guessing? that you are going with a segmental (axe/axed) arch. For ease of design, I have found that using the ID radius of the oven to determine the height of the risers for a segmental arch is very convenient. That will allow all the needed measurements for your plans to be included on one foldable 1/2 template. However, I highly advise a hemispherical arch for larger ovens. A hemispherical arch is much easier to cut, build, and doesn't require near the massive amount of buttressing that is by a segmental arch.

[Macrinehart]

Alright! Thanks to feedback I've enhanced my template so that it includes a cross section of the opening. Armed with a piece of string pulled through the hole in my template and marked for the Interior radius, I drew two layouts for possible opening dimensions.

On the left I have a plan with a 7.5" high opening wall to the base of the arch. On the right is a plan with a 10" opening wall at the base of the arch. The key learning is that the higher sidewall for opening requires transposing bricks to be set deeper in the oven dome, also the front of the opening is correspondingly less deep overall. There are also some differences in how bricks need to be cut where the opening and oven dome intersect. In both cases, after account for an additional 4.5" of depth to the opening in front of the chimney landing, there is plenty of space for the oven landing.

For good measure expanded the opening width by 1.5 inches per side to account for UtahBeehiver's advice on the reveal. Also took UtahBeehiver's advice with peak of arch at 13.25". (Thankfully, I didn't pitch that extra foam core!)

So, question: is there a preferance regarding the hight of the opening walls to the base of the arch?

[MarkJerling]

I think the plans from Mark are the most helpful, and also the picture on the subscription page for the step-by-step guide:

Thank you for your kind words. Only thing with mine I'd change is I'd make the flue gather a bit wider. I believe I constricted it a bit much.

[UtahBeehiver]

Reveal is a bare min. of a 1/2", 1" or 1.5" better. Inner arch height is approximately 63 to 65% if dome height, ie 42 ID oven should have dome height of 21" X .63 = 13.23" with width being more a builder's choice.

[Macrinehart]

Thank you for the feedback. I have tried searching for plans several times but the only plans I have found are from MarkJerling. I know there must be more but my search skills are possibly not up to the task. I did read forum discussions on Oven Opening Size and Leave a Reveal. I think the plans from Mark are the most helpful, and also the picture on the subscription page for the step-by-step guide: https://mailchi.mp/01e62a8f4439/how-to-build-an-oven.

My vision is to build an opening that is 20" wide and 12.5" high at the center with an arched top. Per UtahBeehiver I see that my chimney landing needs an extra half inch on either side to allow a reveal around the rough opening. Also note from MarkJerling's plans that the chimney throat is a rectangular, rather than circular, meaning less depth required for the chimney landing. Thanks to everyone for the tips! I will definitely clarify my plans for that part of the oven before pouring the hearth!

I think one idea I like from somewhere in the reading I did was working with a metal fabricator to form the chimney landing. There's a great place on our neighborhood - Vinje & Son Sheet Metal - that does custom sheet metal fabrication for all kinds of DIY heating and cooling projects. I think I'll take the plans and my template down there and pick their brains, as well as get a fabricated chimney landing. I planned on getting my chimney materials from them anyhow.

[UtahBeehiver]

As Gulf said, start with the eplans, then go to the Newbie Section and look under Treasure Archives for some of the more documented builds as well as the blog for more up to date innovations. You do NOT typically notch the inner arch bricks to make the reveal but rather offset the vent chamber walls.

[Gulf]

The FB Pompeii oven plans are a great place to start. However, there have been a some improvements over the years since the printing. You may want to look at several of the many more recent 42" oven builds on this site before proceeding. You definitely don't want to pour the hearth before adding the correct placement of the inner arch and the outer arch/entry to your template. You will need to settle on a door height, width of the opening, and the style of arch, before a you can begin to determine that placement.

[Macrinehart]

Will you be rounding the back of the hearth form or pouring it rectangular?

I'm doing a rectangular hearth. The positioning of the template was just a rough placement to make sure the stand wall align as intended. I do want the brick dome to be centered over the stand so that the load is distributed directly down the stand walls. I do plan to have the hearth a little oversized.

It appears that the inner arch extends out to also form the outer arch with no reveal for an insulated door?

The oven opening is not drawn with all the detail, as you noted. I will add reveal for the oven door but frankly I am less clear on the detail of how that is accomplished physically. I see the bricks around the chimney landing are full intersecting with the oven dome and excess material on the interior side of the bricks used for the chimney landing is cut off using the indispensable tool to plan the cuts. Then it looks like the interior walls of the opening are notched to provide the reveal. See picture below. Am I visualizing this correctly?



Another factor I am not clear on is the total depth of oven opening. The plans call for 8" for the chimney plus 12 inches for the oven landing. Is the full 20" depth enclosed in the opening arch, or does the plan account for space in front of the oven opening?

By the way, how are those seeming perfect rounded edges an arched notch-out cuts made, that I see picture in the Pompeii plans? (See Figure 5.1 and 8.7)

[Gulf]

I like the idea of using templates. Will you be rounding the back of the hearth form or pouring it rectangular? The reason I ask, is that we just did a rounded form where we cantilevered the oven back just a little further than what you have pictured.

Also, I zoomed in on your template and am wondering a couple of things. First, It appears that the inner arch extends out to also form the outer arch with no reveal for an insulated door?

[MarkJerling]

Looking good.
You could have a play with the spreadsheet per this thread:
Dome spreadsheet calculator - Forno Bravo Forum: The Wood-Fired Oven Community

[Macrinehart]

By the why - is there a trick for estimating how many fire bricks I'll need to complete the high-dome oven?

Interior diameter of 42 inches. And bricks are 9"x2.5"x4.5".

[Macrinehart]

The house may fall down but the pizza oven will stand. LOL

Sounds like priorities are in order!

Last weekend I hired the yard crew to come out and help pour the concrete slab. I pitched in with mixing the concrete...took a break to snap a photo of Constantino (shovel), Manchette (temporary foreman), and Jose with the trowel. 35 bags of concrete plus one week of cure time and the finished pad is looking good!

Today I removed the forms for the concrete pad, and then built the stand. Four blocks short, so had to go back for more. I got two sheets of foam-core craft board from Columbia Art & Drafting, and using yardstick compass and some help from my daughter we drew a full-size template for the oven floor, insulation and stucco to use as a guide for ensuring my hearth is adequately sized. Looks good - I'm planning on an overhang for the hearth and the stand size is adequate to have blocks directly under the dome walls on all sides.

I stuffed the cement bags in every other channel around the stand. Next up - angle iron to support blocks over the wood box opening, and then building the hearth form! I'm going to ask my blacksmith buddy to help with a wood stand, and that will go in before finishing the form.

[MarkJerling]

Depends if you're in earthquake country or not. With the frequent shakes here by us I took no chances. The house may fall down but the pizza oven will stand. LOL

[hillscp]

I dry stacked mine. No regrets.

[Macrinehart]

So - it's been a couple weeks since my last update. In that time I got the slab prep done and hired my landscape/yard service crew to pour and finish the slab. It's been curing for about a week, and I plan on starting the stand this weekend.

Question - dry stack block or mortar? I'm planning on using standard 2 cell blocks, just following the guide for the Pompeii oven.

I'll post pics after I get the chance to edit them.