Building The Dixie Darling

[WarEagle90]

That’s probably not a bad idea. Wouldn’t be to difficult to just run down each edge with the grinder.

[WarEagle90]

4" of CF board and 12 x 12 x 3 tile are all set on the hearth. Inner arch form is set and ready to go. I am questioning myself on how I cut that first brick setting next to the arch. I simply used the IT to mark the cut line as you can see. Would the next brick up use the same line for the bottom and the IT across the top? That's what my mind is telling me, but I am just not sure.

[UtahBeehiver]

The placement of the inside of the arch form should intersect with the line you scribed with pencil mark from the IT. If you are doing a tapered inner arch (recommended) the attached is a pdf showing how the IT helps you lay the arch out. You start with the "top dead center of the arch" TDC and work down either side. Taper Arch Help.pdf

[JRPizza]

Dan, how wide/deep is your form? Mine was narrow enough that the fore and aft edges of my arch bricks could index against it to keep them inline. It looks like your bricks might not hit on front and back till you get a ways up the dome, at least judging by your picture #3. As you build the arch up the bricks will project further into the dome, so yes, the bottom of the brick should match the brick below it and the top should it a line created by the IT. The bricks will have a lower angle that I believe is somewhat tangent to the radius of the form.

[WarEagle90]

Thanks Russell and JR. You both confirmed my suspicion that the arch form is to thick. The way I have it positioned, the outside of the form is even with the back (outside) of the arch bricks. I built it before I had actually laid the oven out on the hearth. JR, I used your method of placing the location of the arch as the photo below shows. I played with the position of the TDC brick of the arch until I got something that looked good to me and that ended up being 14 inches from the center of the oven. Given that dimension the back of the 9" brick would be 23 inches from the center and that is where I set the arch form. So to fix my issue I need to shorten the depth of the arch form so that the inside will intersect the inner radius of the oven at the cut brick shown in the previous post and leave the back at 23 " so I have something to keep the bricks aligned to. Sound about right to you guys? Thanks for all your help. I would not have tackled this project had I had not had the knowledge that the folks that came before me would be here when I had questions.

Russell, thanks for the Tapered Arch PDF. I do plan to taper the bricks as noted in the article.

[JRPizza]

I would not have tackled this project had I had not had the knowledge that the folks that came before me would be here when I had questions.

So true! I only figured out how to properly locate an arch after lot's of help from the forum, and I needed help through pretty much every step of the way! I lost track of the times I told my Wife "the next step is the hardest" The key is don't start mortaring till you have a pretty good feeling about what you are doing!
PS, if you are going to taper your arch bricks to maintain a constant mortar joint (as viewed from the front), ask for help if you get stuck. I have a spread sheet I made that might help with the dimensions.

[WarEagle90]

JR, I'm sure I will have plenty of questions going forward. It all looks pretty simple watching you guys do it, but when it comes time for me to start cutting and mortaring it doesn't look so simple anymore. My plan is to test fit as much as I can before the mortar starts flying. I will most definitely taper the arch bricks, if for no other reason just to prove to myself I am capable of doing it. I think I've got the dimension worked out or at least they work in the perfect world of CAD. I know that doesn't always transfer to the real world, but I think it will get me close. With that said, I would love to see the spreadsheet to see how close my dimensions match up to it. The drawing shown below is without an adjustment for the mortar joints and I will adjust the final dimension to something I can actually measure. I think the final numbers end up being around 2 1/8" at the top and 1 3/8" on the bottom. My plan is to cut all the arch bricks to the left and right of TDC and then make up any difference with the center brick. I bought a few 9 x 4 1/2 x 3" brick so if it turns out I need a thicker brick for that top one, I'm set.

[JRPizza]

Here is a copy of the spreadsheet. I had to zip it as the excel format is not one of the ones the forum is set up to accept, so if you ever have a file liyou can't upload you will need to zip it. That is what I did with my cad files too.
To use the spread sheet, you input into the cells with a green header and get the outputs under the red headers. For the wide part of the brick I used the nominal width of 2.5 inches (W1) and after you input your radius and joint thickness you will get the smaller dimension (W2). You can also vary the number of bricks, but I think an odd number looks best as you will have one brick right at TDC. Let me know if there is a problem or if you can't figure it out - lots of spreadsheets make sense to the creator but nobody else

Also, the FB plans recommend a height of 12.5 for a 42 inch oven, not the 13.5 you are showing. If you do target a 12.5 high opening, your 10 inch radius will fit perfectly on just a single brick, not the two full bricks you show above (your opening will actually be slightly bigger than 12.5 due to mortar joint thickness). This worked great for my 39" oven, as I had a radius of 9.75, so sitting on a full brick I had an opening of 12.25 (again, slightly bigger due to joint thickness)

[JRPizza]

My plan is to cut all the arch bricks to the left and right of TDC and then make up any difference with the center brick. I bought a few 9 x 4 1/2 x 3" brick so if it turns out I need a thicker brick for that top one, I'm set.

Once you get your dimensions, I recommend dry stacking the bricks around your form, and marking the approximate location on the form so mortar/joint creep does not make you have an odd sized key stone, unless that is the look you are going for.

[WarEagle90]

Thanks for the spreadsheet JR. I'll play with the numbers tonight. Now that I go back and look at the FB plans, they do show a 12.5" height for the opening, but I also remember hearing several quotes on other builds, including the beginning of this one, that the recommended height is 63-65% of the oven height which in this case the oven height will be 21". 63% of 21 is 13.25 so that is where I got the number. I do like having that keystone at the TDC so currently I am using 19 bricks in the arch. The arch I posted above is actually elliptical in shape. I really like the way it looks. I have a question re: the opening height. Is the height based on the area of the opening or is there some formula that gives heat loss based on height of opening regardless of cross section (within reason of course)? I ask because you can have a constant opening height and opening width and vary the geometry of the opening, rectangle, constant radius arch, elliptical arch, triangle (not reasonable, but you get my point), etc. and get quite different areas. I'm not looking for a specific answer, just really thinking out loud. Thanks a bunch for you comments and suggestions, I greatly appreciate the help. I'm going to rebuild the arch form one afternoon this week and get it reset before the weekend. My goal for this week is to get the arch brick cut and mocked up and get the first course of the dome set, weather permitting. Calling for rain on Saturday so that might dampen my progress.

[UtahBeehiver]

IMHO, 13.25" will work just fine and within the range for "government" work. But remember, mortar joint thickness will play a factor in the first two flat course which the CAD picture does not show.

[WarEagle90]

You know, I never make as much progress as I plan. This weekend was no exception. I had hoped to get the inner arch form adjusted to the proper thickness and reset, cut the inner arch brick and see how they looked dry fitted, but nope, didn't get there. I knew the weather was going to be questionable this weekend but I felt I had a good full day Saturday to get what I needed done outside and then I could spend Sunday in the shop, out of the rain. Well, I ended up going on a last minute hunting trip on Saturday so that cut out my only dry day. Rain started about dark-thirty Saturday evening and continued until almost noon on Sunday. When it finally let up, I got to work. I had purchased a 12" diamond blade to go on my miter saw, so I installed it and set up a water nozzle that I could adjust to help keep the blade cool and the dust down. As is usually the case, I needed some additional brass fittings to hook it up to a water source and since I am 30 minutes out of town, I decided to forgo the water and attempt to cut one of the arch bricks dry. Now, did I mention it had been raining for almost 18 hours? Well, that turned out to be a blessing. All the brick are out in the open so they were quite water logged and even though I wasn't using water, there was enough moisture in the brick to really not need it. I ended up cutting all but one of the 19 arch bricks in this manner. Blade never got hot and never seem to slow down. I intentionally failed to cut the last brick. I want to mock up the arch and measure the TDC brick to fit snugly. Maybe I can get the arch dry fit one afternoon this week now that the time has changed. Until next time .....

[WarEagle90]

Today I was able to finally get the inner arch dry fit and I think it turned out good. Cut the first dome course and dry fit it also. I am building a tapered inner arch and have received some good guidance from JR and Russell. I marked the ID and OD on the arch and think I have a good understanding of how to cut the more vertical arch brick but as I started looking at the lower bricks I started questioning myself. For example, I designed the arch with two flat bricks on each side before the curve of the arch begins and I know how to cut the first one, but the I'm somewhat confused on the second. If you go by the mark indicated by the IT set at the ID, the brick will extend into the dome beyond the arch form. So do you cut according to the IT or cut to match the form? See photo below. My guess would be to make it match the form. BTW: I did rebuild the form so that the interior edge correctly intersects the dome ID. Installed a couple LED lights under the top so that I could work longer in the evenings during the week. Calling for rain sometime tomorrow so not sure how much I will get done tomorrow. Plan to mortar the 1st dome course,cut the second and maybe mortar it in and get the first couple arch bricks mortared in place. More to come ....

[UtahBeehiver]

You may have to fudge a little here if you want a smooth transition. The IT is a baseline but not all or none. It you do not match to the inside of the form you will have a ledge at the vertical number two brick or you will have to have the arch bricks extend deeper past the back of the form to mate.This is a trial and error process. When you start cutting the arch bricks start at top dead center and work down each way. PS, no one will see this area of the inner dome once finished but for me, it was a challenge for myself to make it look as good as possible.

[WarEagle90]

Thanks, Russell. That’s what I thought but I wanted to get some confirmation. I’m going to cut those two horizontal bricks on either side of the arch and get them mortared in since I got the first course mortared in this morning. I’ll post photos later this evening. Back to work Dan .....