32 Inch Cape Build

[Kvanbael]

When you say you mortared your arch to the floor and regret it..... is that the cooking floor you're referring to or the CaSi board?

Yes, cooking floor. The rest of the dome is just sitting on that floor, but the arch bricks were mortared. During curing I got a crack in my arch and a widened seam in my floor, I’d like think I would have only one of those if I hadn’t mortared them together.

[Baza]

Looking good Cape! Wow - fanastic job on the arch and build is coming along. Congrats!
I put a heat break IN the hearth-flue floor kinda like what you are doing - thermal strips in notched bricks - can't see from the top - but its there - don't know how much of a difference it will make - but some is some - and that's better than none in my books - have a look at my build section on it
I mortared my arch brick to the floor and only thought afterward I might not have done that b/c of expansion issues - hopefully I'm safe
Time will tell
WELL DONE!!
Barry

[CapePizza]

Sharing some progress photos. Just finished the 3rd row. Also had a chance to put my compound miter fixture into action and test it out. Worked well.
Thanks for looking.

[UtahBeehiver]

Nice tight inner joints, do watch out for the inner joints lining up (last pic, left of center are lined up). Try to a staggered bond. One thing, make adjustment on the course towards the front half of the dome, this adjustments will not be seen once the dome is closed. As you get higher, the last thing you do is to lay a brick on the next course at the back of the oven. This will serve as an anchor for that course and especially helpful the higher you go.

[CapePizza]

Thank you for pointing that out Russel. I had noticed the joint in that row had lined up, but it didn't occur to me to cut a few bricks (making them less in width) to avoid that occurrence. And thanks for the tip about laying a brick on the next course at the back of oven when finishing current course. I remember you saying (in another thread somewhere) that you started your courses at the back of the oven and worked your way to the around to the arch. I see the advantage of that in that the bricks that are seen will all be the same size whereas any cut bricks in the front will not be seen. I've been doing the opposite, starting at both sides of the arch and working my way around to the back. I'll change my approach and start at the back of the oven. Appreciate the feedback.

[Neil.B]

Great progress, well done.
This is the point that your dome really takes shape. You will find yourself standing back and looking at different angles, inside and out...well that's what I did

[mongota]

Revised the arch placement design as discussed. Feeling better about this.

Good move. There's only upside to doing the revised version.

[mongota]

Thank you all for your comments. As mentioned I had originally thought not incorporating any thermal breaks. Now just giving it a second thought. From what I get from your comments, using a metal break in floor is NOT the way to go. I did find a previous thread from December of 2017 "Heat break. To do or not to do" which I'm still reading and digesting. Seems, in theory at least, just leaving an air space between floor bricks and vent tunnel bricks would provide a break, but then all sorts of "stuff" can fill that space. Or as Russel had seen, just cut an angle on the touching bricks to create an air space (at least that's how interpreting it). I'm thinking something as simple as the attached image. I thought what BAZA did on his floor for a heat break was interesting. I think what I have in the image is probably similar to what he did.
The space could be filled with ceramic rope or maybe just leave it open, as air is a pretty good insulator. Any thoughts about that, filling it with rope or just leaving it open? As usual, thank you in advance for any help.

EDIT: Found this additional image from a previous post. Also looks interesting.

I did an undercut similar to the photo shown in your Post #100, and filled the undercut with leftover scrap insulation. If you do the inverted "V" cut, I'd recommend not cutting it to a point as shown in that drawing. The point can be a bit fragile. I'd leave a little bit of brick, say 1/4" to 3/8" thickness.

When I started building my dome, I had my floor bricks in place, then I wrapped the outside circumference of the circle of floor bricks with a single thickness strip of cardboard. When my base course of dome bricks were set, they were set up against the cardboard. The cardboard was to act as a spacer between the unmortared herringbone floor bricks and the mortared bottom course of dome bricks. I'd venture that the cardboard was less than 1/8" thick, so when combining the gaps on opposing sides of the dome I had perhaps a 3/16ths of an inch for the floor brick to expand in to. Plus the minor gaps between the floor bricks, even though they are snug to one another.

Your first fires will incinerate the cardboard, leaving an expansion gap which will eventually fill with ash.

That ash filled gap, plus the inherent looseness of the hand placed and unmortared loose herringbone floor bricks, should allow enough free space for any thermal expansion seen by the herringbone floor brick as a whole.

The spec sheet for my firebrick stated the brick would expand 0.4% in length when undergoing a 900F temperature change. For my 42" oven, 42" x .004 is about a 3/16ths of an inch potential increase across the entire floor diameter. The two ash filled perimeter gaps and the inherent slight looseness of the herringbone pattern has been able to accommodate that expansion with zero problems to the dome.

[Baza]

John! You're doing fantastic work! Very clean cuts, terrifically tight joints!
I found the last couple of courses I wound up with some lined up joints that didn't stagger in the bond - have them in a couple of areas - I fixed afterward - but don't think there is too much structural weakness if it is in a couple of places only - I think it becomes a problem when you have an entire run of it.

Love that Mongo chimes in to help - really helps plonkers like me as I check other builds and learn from their questions too!
The expansion gapping was a thing I did because it was de riguer practice on the forum for expansion - but never knew the math .... now I do! phew!
I did a hidden heat break too - have a look at my post #73 - if it helps

Keep chugging along!! You're doing amazing!
Barry

[CapePizza]

Approaching the arch!...... just finished row 5. Some progress pictures attached.

I have to say at this point, two things.

1). My hands are like raw chop meat. Lots of hand salve in the evening.

2) It gives me great appreciation for those who have taken on the endeavor of building a WFO. Not for the faint of heart. Until you undertake building one yourself, you don't realize the amount of planning, artistry, craftsmanship, openness to learn, humiliation, and overall, what's involved, and the satisfaction you get, to create one of these structures. I'm having very much of a good time. I'm feeling part of a special group of individuals. And I'm looking forward to cooking in my oven!

MORTAR ON!!!!

Edit: Meant to say thank you for your encouragement, Barry, Baza. I did see your photos regarding your heat break. Still thinking about what to do with that, thanks for sharing your process. I was just taking another look at your thread. Very impressed with how clean your build is and your tight fitting brick work, as well. And, yes, I'm learning to live with those lined up joints on rows 2 &3. Certainly paying more attention to that and trying to avoid that from happening again.

mongota and thanks Mongo, for your thoughts on the heat expansion. I did leave the cardboard spacer between floor and outer half header row. The expansion specs on the brick is very helpful. Thanks!!

[Neil.B]

Glad it's all working out after all that planning, it look great.

You missed worry of your list

[CapePizza]

Thank you Neil.B. "Worry" is not on my list (for this project).

[Neil.B]

It was/is on mine. I think I've worried about every aspect

[mongota]

I have to say at this point, two things.

1). My hands are like raw chop meat. Lots of hand salve in the evening.

If you're getting mortar on your bare hands, when you're done working, wash your hands. Then over a sink, pour a slug of vinegar in your cupped hand, and rub it all over both hands. Maybe repeat once. Wait a bit, then wash again. The vinegar (low pH) can help neutralize the alkaline burn effect mortar (high pH) can have on your skin.
Then hand salve. And have a beer. lol

[Baza]

Hmmm - I tend to go straight to the beer part at the end of it all .... no wonder my hands are like a brillo pad!
mongota Thanks for getting the order right!

Great build - John - love how you mention humiliation - that moment when the brick you thought you cut just perfect is ... well, not - and you keep going only to note that it was on course 3 and you're on course 8 and it will forever stare at you ... laughing

yeah ... that