42" build in Central Texas

[Tscarborough]

Re: 42" build in Central Texas

Beat up some firebrick scraps into 1/4" to 3/8" chunks and add them to the mortar at about 1/3 to half the mix, then fill the gap. Do not utilize the dust from pounding the firebrick, just the aggregate. Your basic refractory concrete.

[kbartman]

Re: 42" build in Central Texas

GAC,

Looking good, your dome is coming along nicely.

As far as the gap, I feel your arch transition turn out well. I think any mortaring would just end up in your pie's. Just my opinion, curios what others think though.

[GarnerAC]

Re: 42" build in Central Texas

Here is that Gap I was referring to. Should I mortar it up or let it fly? If I mortared it up, the mortar would be an inch thick, plus I would be adhering it to dry mortar now.

[GarnerAC]

Re: 42" build in Central Texas

Cranked out another couple of courses in the last week. No major problems getting into the dome. The bevels and angles were a pain to get right. I had a tendency to get a tad low across the dome because of the corner pieces that contact the arch but I have corrected that and should be spot on level at the next course.

The reason it looks wet is because I have had damp towels draped across the top so that it doesnt dry to quickly.

There is significant gap under the 7th course that Im not sure about,(4th photo kinda shows it) as it goes across the arch. Its smoothly mortared up in the gap with no holes or openings but an inch or so gap where the vented smoke and exhaust will have to stumble across. I didnt want to completely build it up with mortar. Any thoughts?

Race weekend in Katy so no working till next week!

[Tscarborough]

Re: 42" build in Central Texas

Unless you get 3 vertical joints in a row, I wouldn't worry about it, especially if they are even just lipped.

edit- I can tell by looking at it that you are trying to clean it up while the mortar is wet. Let it dry to the crumbly stage, then it cleans without smearing.

[GarnerAC]

Re: 42" build in Central Texas

Dove season starts tomorrow so this may take a back seat!

A few more pics:

[GarnerAC]

Re: 42" build in Central Texas

Made some decent progress the last 2 days. 6th row almost done. Gravity is starting to show its face. Inner arch done. Im now starting to see how the bevel is important for good inside joints. My mortar joints are about 1/16" -1/8", a couple slightly larger. Being very careful to get good adhesion between bricks. No voids, buttering both bricks and keeping everything moist. I see some of you with even smaller joints! The ones that kill me are the triangle pieces where the dome meets the arch, Brain busters with all the angles. Im really trying to keep with the bigger bricks and no "potato chip bricks". There are a couple vertical joints that bug me. Thinking about cutting 3 bricks out and re-doing them. Hmmm. Going smooth, having fun. People stop by and chat and look and have no clue what the end will be. They look under the stand and think the fire goes there!

[Tscarborough]

Re: 42" build in Central Texas

Yeah, it does not have to be exact, that is just the goal you aim for. Regarding the ceiling height it is the same unless you start talking low dome, which would be 14-15" height.

[david s]

Re: 42" build in Central Texas

When should i start dropping the dome height. If i leave my IT alone it will be 21". Any advice on when to adjust it down to 20"?
I was really happy with the insulation board. It was so level and consistent. Never once had to use sand or any leveling agent under the floor bricks. Floor height is 44-1/2"

The 63% rule is not crucial. A 1" difference in height will not change the way the oven performs to a noticeable degree.if it were mine I'd just keep going the way you are now and end up with a 21" internal height.
I tried playing with altering the ratio with my design and the results showed no difference in firing and performance a few percentage higher or lower.

[texman]

Re: 42" build in Central Texas

Not real sure on the changing height. But i would start it now. You will want the bottom edge of each brick to line up with the course below, so i would shorten the IT 1/2" on this course and the other1/2" on the next. You will line up the bottom of the brick you are setting with the top of the one below it and then tilt it until the top edge of brick lines up with the IT. you will need some kind of spacer to fill the gap between the bottom of the brick and
the IT. that way, you wont have a lip between courses. Make sense?
One of the sages probably has a better trick.
Tex

[GarnerAC]

Re: 42" build in Central Texas

With a 20" dome height (I wouldn't go any higher than that, lower is fine), you need a 12.5-12.75 inner arch height. Keep it at 63% of the dome height and you are gold.

For the backside voids, fill in enough to stay in place, then use the ends of your batches to fill the rest. That way you never waste any mortar.

Looking good!

When should i start dropping the dome height. If i leave my IT alone it will be 21". Any advice on when to adjust it down to 20"?
I was really happy with the insulation board. It was so level and consistent. Never once had to use sand or any leveling agent under the floor bricks. Floor height is 44-1/2"

[GarnerAC]

Re: 42" build in Central Texas

Got the 3 rows and floor all cleaned all up and covered w 2 layers of cardboard. Worked a little this afternoon, got a 3rd row done and got the arch supports ready. Im struggling with the arch angles. I guess i should have paid attention in Geometry class back in high school!
Finding that my diamond blade on a angle grinder is a very useful tool. It was almost 100 degrees today, a little tough to work with mortar. Went through about 5 spray bottles of water keeping things moist,

Whats the best way to cut the half-brick arch angles with a 10" saw?

No pics today. Maybe ill get some done tomorrow afternoon. The wife has been great, not a word about the latest backyard time and money consumer

[Tscarborough]

Re: 42" build in Central Texas

Regarding droppings, if you just leave them alone until they are what is known as "fingerprint dry", they will come right off with no muss no fuss. When you mess with fresh mortar droppings or even on the joints, you just smear it around and make a mess. You should just leave excess mortar on the joints and the droppings alone until they dry enough that they are crumbly but not hard, in the range of 15-45 minutes depending upon the hydration of your mortar and the temperature.

[kanoer54]

Re: 42" build in Central Texas

build looks nice so far.
ditto on covering the bottom of the oven to keep mortar droppings from sticking to the bottom of the oven. the higher you build, the more droppings and splatters seem to build. also, one thing i found, it is a lot easier to clean the dome interior as you go rather than waiting till you are almost done with the dome and don't have any light or air. it can get pretty claustrophobic in there and really hot!
jon

[Tscarborough]

Re: 42" build in Central Texas

With a 20" dome height (I wouldn't go any higher than that, lower is fine), you need a 12.5-12.75 inner arch height. Keep it at 63% of the dome height and you are gold.

For the backside voids, fill in enough to stay in place, then use the ends of your batches to fill the rest. That way you never waste any mortar.

Looking good!