Mongo's 42" CT Build

[jonv]

Nice. Will be pleased if my own build looks as tidy! Great job on the plug.

[JRPizza]

Dome came out looking beautiful! Now for the next adventure, the vent and chimney

[mongota]

That'll be it for now. It'll be about a week before I get any more time to work on it.

[mongota]

The completed dome. Pretty messy with mortar shmears all over. I can only fit about 30lbs out of my 260lbs through the opening to clean it up, so I'll have to wait a bit on that.

[mongota]

Cut the plug. Wanted the inside face of the plug to be not more than 4" so when I beveled the sides outward, the other face would still fit the 4-1/2" width of a half-brick

[mongota]

Got the dome plugged yesterday.

Made a template of the hole and then divided it onto eight sections to shape the eight brick for the last course. Sized the last course so the octagonal plug would not be more than 4" across. Then dry fit the last course.

[thevance53@gmail.com]

Slow down man, you are passing me up! Looking good. Those steeper angles are easier in some regards (don't have to level them as much), but they are much harder to keep everything fitting well and getting the joints filled all the way. Good luck. I hope to show you my plug this weekend.

[mongota]

Got two more courses done late today. Tomorrow will be the final course and the plug.

[mongota]

Either three courses and a plug to go, or four and a plug.

Probably four, but my lower back is hoping for just three and a plug.

And my little ladies aid crutches to keep the already set brick from shifting when I tap the next brick in place.

[mongota]

Got rained out yesterday, but got the ninth course and part of the tenth done today. I'm hoping to plug the dome Thursday. Slightly slower going with the steeper angles.

[staestc]

Wow! Looking good, and a ton of progress over the last few days.

[mongota]

Got the dome arch covered today. A couple of starts and stops due to intermittent rainshowers. Rain normally wouldn't be a worry, but I didn't want the board insulation to get wet.

[mongota]

Nothing earth shattering, haven't been able to work on it for the past few days. But Thursday I got a couple more courses of dome brick set, finished the arch, and pulled the arch form.

Also have a pic of an anchor brick. When starting a new course, I'd set about 5 brick on that course, then set an anchor brick on top of those five brick to act as an anchor brick for the next course.

The idea being that by the time you get to the next course, the anchor brick is fairly set, so it gives you something sturdy to set the new bricks against. I'd set my anchor bricks with a proper mortar joint offset opposite of the dome opening. I'd then work to the left and right of the anchor, moving towards the arch.

Once I got two bricks on either side of the anchor, I'd set the anchor for the NEXT course, then go back and finish the course I was working on.

Onward and upward.

[mongota]

This was my method for figuring out the cut lines for the dome arch bricks. This was confusing to me until I started building the dome, once I saw it with my eyes it became so very simple.

The red line in the drawing represents a line radiating from the center of the dome floor, essentially, the IT. I used my IT to get my cut points, but a string anchored to the center of the floor would suffice as well.

The yellow dot represents the inside radius of my brick dome, for a 42" oven, that'd be 21" from floor center.

The blue dot shows where the bottom of the arch brick meets the inside face of the plywood arch form. That may also be 21" from center, or it may be slightly different. It depends on where you place your arch form and the geometry of your oven opening.

The orange dot represents the outside diameter of the brick dome, for my 42" oven that would be 21" + 4-1/2" thick brick = 25-1/2".

The basics of the layout? With the brick in its proper place on the arch template form, position the IT (or string) next to the side of the brick so that the outside diameter marking (orange dot) on the IT or string intersects the top edge of the brick. Holding it steady, mark the location of the orange dot, and on the side face of the brick, mark the inside diameter of the dome (yellow dot). You can now set the IT or string aside. Mark the blue dot on the underside of the brick where the bottom edge of the brick meets the inside top edge of the arch template form. You'll connect the orange dot to the yellow dot, and the yellow dot to the blue dot. Those are your cut lines. Because the geometry of the dome/arch intersection changes a bit as you higher up the arch, you can mark both sides of the brick and adjust your cuts as needed.

I built my arch from the left and right feet of the arch, simultaneously moving upward, meeting at the keystone brick at top dead center.

Prior to cutting any brick, I placed my arch bricks on the arch form, shimming them in place. I chose to not taper them. I aligned the outside edge of each arch brick with the outside face of the plywood arch template. With the template being plumb, that'll assure the face of your arch is plumb. The bricks will overhang the arch template, projecting inside of the dome. With the arch bricks shimmed in place, mark on the outside face of the arch template where the left and right edges of each brick sit on the arch form. You'll be taking the bricks off and replacing them, the marks assure that when you replace them you'll keep your planned pattern, spacing, and layout, and when mortaring them you'll prevent mortar joint creep. Number the bricks so you get them back in their correct spots. I numbered them L1, L2, etc, for the left side of the arch, and R1, R2 for the right side.

I used the IT as shown in the photo to get the cut points on my L1 base brick. I connected the dots, cut the brick, and mortared it in place. I then shimmed my second L2 brick in its place. I transferred the cut edges of the already mortared L1 brick to the adjacent side of the L2 brick, and used my IT (or anchored string should you prefer) to indicate the orange, yellow and blue dots on the "upper side" of the L2 brick. Connect the dots, skewing the lines as needed. Make the cuts. Mortar L2 in place, paying attention to your layout lines on the arch template, and move on to L3.

You can cut and dry shim them all first, then mortar them later in a single batch. Or cut and mortar one at a time. Either way is fine. Just stay on your layout lines.

[mongota]

All right, I got three pics to upload. One of the slab covered with RedGard, another showing the 4" of board insulation with the floor brick, and a third showing the arch (keystone not set) and the first three courses of dome brick complete.