Hearth size

[JRPizza]

Gulf, on first brick placement, I am showing two options, the brick on the right was my original, where the innermost face is tangent to the circle representing the outside of the dome. The brick on the left has the outermost face tangent to the outside of the dome. I was thinking of building the arch like the left brick if that is not too far back. As a retired airplane guy, I like the idea of indexing the point of the brick to some feature rather than having it float between, unless there is a reason I should pick something between the left and right views. Any suggestions? Also, what program are you using - is it sketchup? I am using freecad since I have it and use it to make models for my son's 3D printer.

[Gulf]

I think that I would choose something in between. The option on the left has the bottom arch brick only about 2" thick at it's shortest point. That is an area that you will be pushing an insulated door up to. I think it needs to be a little thicker there. I don't think that I would let it get any narrower than 3.5" at that point. The one on the right is already at the intersection of the inner diameter of the dome. The dome will pull away pretty fast from it with each course. That is just a little forward from where my arch is laid out. But, I had to extend the top 4 courses of my arch to make it work. Also my dome and arch brick are 8" brick.

I just did a rough full size profile of a 36" dome and with an 11.75 height entry. It doesn't appear to me that even a 9" brick would have enough reach without extending. I would have thought it would. I may have missed something, I will look at it again. Try drawing the profile in sketchup and double check me. Maybe someone else will weigh in. But, there is always the squirrel tail fix.

I don't have sketchup or any other program. I use Microsoft PowerPoint (not to scale) to bring out details sometimes. I do most of my scale drawings with an old drafting set. For the full size profile of the entry I mentioned above, I will need to clean the top of the chest freezer before my wife gets home .

[JRPizza]

My current plans are for a 39" oven. That should allow me to put 2 24X36 inch ceramic boards together and have insulation come to the outside of the dome @ 48 inches. The FB plans put the door height at 12 for a 36" and 12.5 for a 42", so I was going to shoot for 12.25 as close as I can make that happen.
You have a pretty keen eye - my cad program tells me that the option at the left gives me a 2.4 inch thick brick at the entry, which for my plans about 1.5 of that would be exposed on the entry side. The option on the right shows about 5 and a quarter inch (5.27) so that is over twice as thick. If I split the difference I Get around 4", which puts the centerline of the brick on the outer dome circle. I'll see if I can get a side view done.

[JRPizza]

Here is a side view with the brick all the way back, like my left hand option, that shows at the center of the arch my 9 inch brick will leave a gap. If I move the bricks forward I'll get a bigger gap, so I am more confused now than I was before. I tried reading some posts on opening details, but the links are still messed up.

[JRPizza]

[Gulf]

I can't see your side view for some reason. You may add it in an edit. I will take your new oven dimensions and do a full scale on the freezer after SWMBO leaves for work tomorrow . Don't sweat it, there is a solution.
EDIT: I can see the side view now. I would rather do it full scale. I will let you know what I find.

[JRPizza]

Great! Just left you a PM telling you how lame this all makes me feel ;-) Looking forward to seeing what you recommend.

[Gulf]

Sorry for the late reply. I did another full size profile. This time for a 39" id oven with 12.25" H door. I came up with the same thing that you have in cad.. I also did a little more looking around. It's not as easy as it used to be. Thank Lburou for his thread that helps. Remember, I extended my arch bricks in. I had thought all this time it that was because of my using 8" brick and sitting my arch too far forward. But, It I now see that it takes a little more than that. You will be able to set the arch far enough in, much like your first option to make a 9" arch work. But you will loose just a little of the inside diameter of the oven That will only be at the corners of the arch, though. The thickness of the base of the arch is maintained by squaring the base arch brick and not following the inside curve. I think that you are on the right track with the drawings. But, do take a look at GianniFocaccia's OctoForno. It is the perfect match for you. His is a 39" oven and he shows plenty of detail for laying out and building the inner arch. I hope this helps..

[JRPizza]

Thanks for pointing out the the Octoforno is a 39 - I had read 42" early in the thread and didn't notice the plan change. I have been reading the 39" Stargate and it appears that he aligned the face of the brick with a line tangent to the floor circle, not the outer edge to the outside of the dome as I did in my side view above. Moving this back just a little more places the entire dome within the arch at the center (see attached pic) vs having a slight mismatch in my earlier side view. Is this what I am looking for - not having that mismatch at the top?

I am pouring my hearth Monday and these small movements are not going to change my plan so I am good to go as of now. I just want to get the locations straight for when I start cutting and dry fitting.

[Gulf]

I went back to my full size profile. I think that the face of the inner arch needs to come back out to about 1" inside of the outside circle of the dome, center of the door. I can't seem to make it work by overlaying your drawing. But, by doing this in full scale it appears to workout. I was able to "guestimate" a cut for your top dead center with a 4.5" bed for the course which will clear the arch. It will have about 2" at a 90 degree angle which should approximate the curve of the id of your dome. I am sure that sketchup is a good program but, I do suggest that you do a full scale on some poster board before you start cutting brick. Good luck on the pour.

[JRPizza]

Your view showed me what I was missing in my mental model, I was not accounting for the angle at the top of the arch. I will take a crack at incorporating that into my layout. Thanks a bunch!

[Gulf]

Your view showed me what I was missing in my mental model, I was not accounting for the angle at the top of the arch. I will take a crack at incorporating that into my layout. Thanks a bunch!

Me neither , You helped me to decide to go back to school .
And, your very welcome.

[JRPizza]

Gulf, I know the full scale layout is the best bet, but I can learn a bunch using my cad program. My playing around and looking at your sketch have generated a few new questions. First off, I am pretty sure I want to have a 4.5 inch face on the angle of the arch brick, which is what you dimensioned - I had to drop the angle of the cut a little to make the face span from the inside to outside of the dome (my first photo). Is this correct, I want the full 4.5?
For some reason my program is giving me direct measurements (in black) in metric, but my input dimensions, shown in red, are in inches. That is what you get for freeware I guess ;-).

The other two pictures are moving the brick to the left and right showing the envelope I "could" place the brick and still have the full 4.5 inch face. Either way I get about a 1.8 inch (~46.6 cm) dimension where you were showing about a 2". I probably want to move the brick to the left as much as possible to maximize my cooking area as you mentioned previously, but wanted to see if I was thinking correctly.

[sharptailhunter]

JR,

Looks like you're well on your way. I recently started my build and found the entry arch a bit daunting at first. Initially, I tried building the whole arch at once. Then, thanks to RandyJ, I was tipped off that the bricks needed to get longer as they neared the apex, like Gulf has shown. So, I started over and have been building the arch as I go up each chain. I also moved the entry arch back into my dome to the point of the leading edge of the entry arch bricks meet at the outer edge of the dome ring. You can see it here in this pic:


You can also appreciate how quickly the dome starts to pull away from the face of the entry arch. In that pic I don't have many dome chains per se but you can already see how they are sloping away from the face. That means each arch brick has to grow to match that.

I don't have a side shot of the arch from the point of where I am with my oven now but here's a front and back view, if any of them help... I can take a side shot later after I get out of work.


Not sure if any of that makes sense or helps, but keep up the good work, we'll all be excited to see your progress,
-Alex

[Gulf]

Alex,
Thanks for coming in. I need all the reinforcement that I can get. The more eyes the better imo. I hate that you had to redo your inner arch. Things are looking great now. I know that a lot of people say that it is best to build the arch as you go, but I found it convenient to finish it and get the form out of the way. In my way of thinking, once you have the concept down, and are using the IT and/or templates, the arch will be the same.

JR,
Yes, I think that you have it. Your pic #2 looks to be exactly what I got in full scale. That maximizes the usable reach of the 9" arch brick. I could be off one tenth of an inch by not accounting for the fat pencil lead that I was using . From your pic, it looks like you also have about what I found to be for the set back from the outside circle of the dome at the center point of the door opening. I found that to be about 1" give or take a pencil lead lol.

Joe