39 inch Corner Build

[JRPizza]

I've been working on my oven for a little while and have been debating starting a build thread, as I probably won't have much to add in terms of artistry or inventiveness over the excellent work already posted on this forum. That said, I thought I would share what I have done and hopefully continue to get support from the great folks that have been helping me so far and others that might chime in. I have used CAD for my initial layouts that some may find interesting.
I'll start with some pictures to show progress to date. First picture is the patio where the oven will be located. My Wife and I stained it ourselves and were pretty happy with the way it came out. Note we had supports sunk in the concrete for the uprights needed for the shelter we wanted to build. We weren't totally sure how big a structure we wanted or how the oven might look so I made a layout using Freecad.

[JRPizza]

Here is my layout - I thought I would be able to nail down the location of the chimney so I could locate my rafters, but I realized how little I had figured out about building an oven. We build our shelter/structure but had to leave the roof rafters loose till I have the vent location nailed down. Now to decide how big of an oven to build. Lots of time reading posts on this forum, then started doing some more detailed layouts.

[JRPizza]

I spent hours researching hearth size and there didn't seem to be as much definitive information for corner builds as for rectangular ones, so I bought a bunch of cinder blocks and started looking at build posts to compare oven to hearth sizes and how much room the builds ended up using. We settled on a 39 inch build, as it seemed like a good compromise between 36 and 42, would give a 48" dome OD which seemed to fit with insulation board dimensions well. I've already shown my cad/hearth layouts on a previous post but will show again for continuity. I wanted to get an idea of where on the hearth to put my oven, to minimize space on the sides and maximize space for vent/landing. First pic shows the foot print of an oven with a 39" ID, 4.5" bricks, 3" of insulation, and 3" of some kind of outer covering. I moved the oven back to give me an inch to play with on the short sides. I also wanted to give the maximum amount of space at the front of the oven under our shelter so wanted to understand how big of a "flat" to put on the corner. This is where once again I realized I didn't really understand all the build details I needed to have nailed down, so I started reading about inner arch and vent design. Got some good help from Gulf and RandyJ in understanding some of the finer points and was able to use my cad program to figure out where to start my inner arch. I think a lot of us come to the forum looking for "place it at X inches" and are disappointed that we can't find that kind of detail, but as cliche as it sounds if you can't figure it out yourself you aren't ready to build your oven. I made a side view of my dome with a brick at the top of my planned 12.25 inch opening. Moved the brick in and out of the oven to find out what looked like the best location to ensure I could tie the inner arch into the dome without having to do the "beaver tail" that others have when the arch was placed too far forward. I also took Gulf's suggestion and drew a full size oven on some cardboard that I used to validate my CAD sketch. I placed the layout on my hearth and validated the placement/clearance that my model gave me.

[JRPizza]

Here's the hearth build, and a link to some of the thought that went into sizing linked below.
I went with the hardibacker approach as it cut down on the time needed to frame the hearth. I had a sheet of 1/4 inch but got worried about the strength so bought two sheets of 1/2 inch. One sheet spanned the gap perfectly and I only had to do a little trimming on the rest. I had planned on a 4" thick hearth, and realized with the thickness of the cement board I needed to have 4.5 inch at the edges to get 4 inches in the middle. I ended up with about 11 inch centers on the rebar with the way it tied in to the cores but I figured a little overkill on the hearth is way better than under doing it.
https://community.fornobravo.com/for...rth-size/page3

[UtahBeehiver]

Do an album, corner builds are not as common as traditional square builds and we all learn something new all the time. Nice start BTW

[JRPizza]

I'm having trouble figuring out the forum. If I do an album, do I stop posting pictures in this thread, or do I double up? Also,I went to the album forum and it looks to me like it is still broken?

[Gulf]

I'm having trouble figuring out the forum. If I do an album, do I stop posting pictures in this thread, or do I double up? Also,I went to the album forum and it looks to me like it is still broken?

I agree with Russell,
Check out Picasa and Picasa Web Albums. It will organize and mirror your pic files and those that you want to upload to an off site album. Of the files that you want to upload, you decide who will view them. When the forum gets up of it's AS you can always copy them back to an album here on site. But, don't quit including pics in your posts .

EDIT: That will also be a backup to any future forum migrations .

[JRPizza]

While I was waiting for my hearth to cure I built my version of the indispensable tool. The IT topic has been covered extremely well and I heavily borrowed from designs I saw. I found some scrap metal I got to practice my welding (I need lots more practice) and bought some threaded rod and some nuts to fit on it. Notice I went without a turnbuckle. I was sweating how to be able to do small adjustments in length without one, then thought about it a little. My threaded rod is 7/16 with 16 threads per inch. I can fine tune my adjustment within 1/16 of an inch by doing a full rotation of the rod, or by 1/32 by doing a half rotation of the rod and flipping my IT 180 degrees about it's rotational axis. I could not fathom needing more than 1/32 of adjustment, so I skipped the turnbuckle. Threaded an extra "jam" nut on each side to hold everything in place once adjusted. I also saw jcg31's attachment of a pencil on the end of his IT but was not sure where he got the pencil holder or how it was attached. I made one by tack welding a 7/16 nut on a section of square tube, then drilling a small hole on the opposite side and tacking a 1/8 nut over the hole. Put a fastener through the nut/hole and had a thumb screw to attach my carpenter's pencil. I borrowed from Gulf's design to attach my IT to the center of my floor. Cut down a piece of 2X6 to match the size of a firebrick and started laying out my floor. I came up with a position for my wood brick that put my IT in the center and aligned points of my herringbone along my centerline. Drew a circle at 48 inches for my dome ID, since I'm building my dome on the cooking floor. Cut and numbered my bricks and went to pick up my Insblok to insulate the hearth.

[DavidApp]

Hello JRPizza

Everyone's build thread helps someone. Also people can follow your progress and it is easier to offer advice if people can see what you have done up to that point.

I learned a great deal by reading a lot of threads that I did not post to but the thread helped me to see something that was causing me problems.

David

[gastagg]

You seem to be approaching it very thoroughly. Looking forward to seeing the progress. Two other corner builds that I think are impressive. MrChipsters and RandyJ's.

[JRPizza]

To figure out how much insulating board I needed, I went back to the forums and my model. I found an arrangement that would use 6 12X36 boards of Insblok, but would require me to lay my bricks right up to the edge of the boards. Time will tell if this was a bad idea or not. I'll wrap my blanket down to the hearth, so my main worry is bearing strength being so close to the edge. I found that the 2.5 inch thick Insblok 19 comes 6 boards to a case, so I bought 2 cases for a 5" total thickness. My original plan was to have 4" of insulating concrete plus 1 inch of insulating board, so going with 5" of board let me eliminate the perlcrete and keep the planned floor height. I used my IT to mark my 48" circle and cut the first layer of board. I flipped the cut boards over and used them as a template to cut the second layer. When flipped back over I had two layers without any overlapping seams. I am going to work without the landing and it's insulation while I build the dome to avoid damage to the Insblok during construction. I have seen folks apply some insulating concrete too for protection, which I may try. My hearth and boards are currently soaked due to recent rains, which has me worried about moisture ingression. Need to get it dried out and some better way to cover when it is raining.

[UtahBeehiver]

When you start laying your brick dome you will have some leftover mortar, use it on the insblok and it acts as an abrasion resistance coating to protect the insulation while you do your build. You may need more than a 1/32" adjustment especially near the dome/arch interface. You can always cut the unithread and add a threaded couple for more range, There were times I move the IT as much as 1/2" to brings things back into round. I assume you are going to lay the dome on the floor and not around the floor..

[JRPizza]

Using mortar for edge protection is a great idea - thanks. IT adjustment won't be a problem for me - I had more than enough extension to draw a circle representing the 48" dome OD and probably a good 10 inches of adjustment going the other way. Since my IT rotation point is at the true centerline of the oven, I'll only have to account for the ~ .5 inch that the pivot point is above the floor. Otherwise I would end up with a 20 inch tall oven on a 39 inch floor.
What method did you use to gauge your adjustments (eg. string from centerline)?
PS, I sent you a PM

[Gulf]

I wouldn’t sweat that half inch. Not until, I was at least clear of the inner arch. There are two things that get the courses of an oven real out of shape imo. One, is the inner arch not reaching far enough into the oven to meet the inside curve. The other, is the “dreaded droop”. I think that you have compensated for the arch. The droop is easy to avoid too. Check this pic out from Colin’s build (Oasiscdm). He is using the floor as a reference point to keep the bricks level over the inner arch. It doesn't have to be a level. I've seen others clamp a stick to the IT. Just set it on the last true brick for that course before laying into the arch.

[JRPizza]

You seem to be approaching it very thoroughly. Looking forward to seeing the progress. Two other corner builds that I think are impressive. MrChipsters and RandyJ's.

I had seen one of those builds but thanks for pointing them out. The one closest one to what I am trying to build was done by UtahBeehiver (https://plus.google.com/photos/10287...21083003687777). I'm going for similar placement farther back on my hearth and an entry without any cantilever. We are planning on putting two walls on our enclosure and want to maximize the amount of room under our roof for hanging out in the Seattle rain.