Texman Build

[texman]

Re: Texman Build

Well, give me the idiot of the year award on Fornobravo. I was trying to remove a brick that was off bond and ended up cracking the back oven wall and broke the arch. Enough of that.

I have cleaned the brick and i am starting over. I am sure i will have a better oven because of all of this.

I have two questions before I resume my build:
1. I am using 2" of FB board as the only insulation under my oven. Is that enough or would you all recommend more?
2. One of the "brickies", or whoever knows; What do i need to do to the bricks that have had mortar on them? Use them as they are (after knocking off the old mortar of course) or clean them with acid or something?

Tracy
Dont look at the pics, they may bring a tear.

[Amac]

Re: Texman Build

i think i discovered my problem that is causing the droop as well. Lying in bed, trying to sleep, thinking about bricks, angles, circumference, etc., i came up with the measuring from the center-line of the back wall of the oven to each side of the arch. Mine is a bit off, so the arch is not exactly square to the center-line of the oven. About a 1/4" i think, enough to cause droop i bet. Anyway, i can deal with that for sure. Just trying to understand what happened.

It may well be a contributing factor in your case tracy - but in general I don't think that is the normal cause. If you build your arch and dome using the IT with the same radius set from the same central point then that should not be a problem unless there was some movement in the IT. I see it as more of an optical illusion. The fact that the arch is in the way means that there is no natural support underneath for the bricks attaching to the arch. The other bricks cross a vertical joint at their centre and both ends of the brick are supported and the centre of the horizontal joint is a little wider. But when we come to that brick we try to make the horizontal joint parallel which it shouldn't be. It should be tipped up slightly.

Gulf's system using the level with the laser attached is the best solution I have seen.

http://i438.photobucket.com/albums/qq105/GulfCoastScooter/Oven/192-1.jpg

I had actually picked up one of those from Lidl a few years ago but it disappeared somwhere

[Gulf]

Re: Texman Build

"Come on, ............. Do you want to live forever?
Seriously, I wouldn't burn something like treated wood in my oven, my fire place or even on a bonfire in my yard. I would not burn pressboard to heat my oven or smoking meat. However, I don't think that anything from the naturally occurring sap from coniferous trees (since the turpentine, non condensable gasses, Methanol etc. has either been recovered for more profitable use or burned on site) would survive the increasingly high temps of the curing fires.
Just Say'n .

[deejayoh]

Re: Texman Build

If it's masonite, it's probably ok to burn as that stuff is steam pressed with no glues. If it is something with bonding resins in it I would not personally want something like that burnt in my oven. Who knows what they use for resin.

[texman]

Re: Texman Build

Dang good Idea! Thanks Gulf.

[Gulf]

Re: Texman Build

I may go ahead and score the cuts now, i will be glad i did when i am trying to work through the arch opening.

Why not just burn it .
Laying flat against the floor, I imagine, it would burn quite slowly. By the time your curing fires are done I think that it would probably be mostly consumed.

[GianniFocaccia]

Re: Texman Build

Tracy,
I wouldn't be concerned about the inner arch not being 'square' since you can bring the dome back to round in a course or two. Despite the hours of lost sleep contemplating everything WFO, my dome is not perfectly round. Believe me, I re-cut 3-4 dome/arch bricks until they fit my requirements for minimizing droop. In every case, the re-cut brick ended up being larger than the original.

The hiccups and imperfections are what make your oven what it is, and is a personal testament to your hands - it's signature, if you will.

John

[texman]

Re: Texman Build

Dennis
I have wondered that too. It is thin 3/16" pressboard. I thought i would just break it and take it out in pieces. I thought i could rip it with a circular saw if i need help breaking as long as i don't cut too deep. I had plans to cut in three pieces and got busy. I may go ahead and score the cuts now, i will be glad i did when i am trying to work through the arch opening.

[deejayoh]

Re: Texman Build

Tracy -
Looking at your pictures, it looks like the wood you have on the floor is a single piece. Are you going to be able to get that out when the dome is done? I cut mine into three sections so I could slide it out the door when everthing was closed up.

[texman]

Re: Texman Build

Nate
This drawing may help explain the arch process better. I think it could be done with 17 bricks for an 18" arch. I went to 19 bricks because it is easier to remove more from the brick than less. The wet saw blades are flexible, not completely rigid. So, if i used 17 bricks, the cuts would have to be very exact on the 2.5" end (top) By using 19 bricks, the cut is deeper and the blade has brick on each side as it cuts(if this makes any sense) You get straighter cuts this way. The drawing is off a little, but i think you will get the idea. I made the actual size version and then cut the template once i had the drawing done.
I removed the "droopy" offender last night using the angle grinder and a screwdriver. Not too bad, just careful around the arch.
i think i discovered my problem that is causing the droop as well. Lying in bed, trying to sleep, thinking about bricks, angles, circumference, etc., i came up with the measuring from the center-line of the back wall of the oven to each side of the arch. Mine is a bit off, so the arch is not exactly square to the center-line of the oven. About a 1/4" i think, enough to cause droop i bet. Anyway, i can deal with that for sure. Just trying to understand what happened.
Tracy

[texman]

Re: Texman Build

THE droop offenders...
I will use the angle grinder and remove the two bricks adjacent to arch. the one on the left (facing oven) is the main offender. notice the gap overhang in the pic. The right one is not so bad, but i don't want to fight this every course. I think (hope) the trick is USE the angle grinder here. Don't use a chisel and wale away next to the arch, cut the brick out. Even in pieces is better than destroying the arch at this point. I could fix with shims, but i am already seeing things i don't like and have gained a little skill so i want to slow down and get things corrected while i have the chance. I think the lower courses may be off as well, but i will correct from course 5 an up. Onward...
Tracy

[texman]

Re: Texman Build

Nate
I drew the arch out on poster board, actual size. Used a little math.
circumference of a circle = pi x diameter. So circumference of a radius = (pi x d)/2 of half of whole circle. I wanted an 18' arch width,(radius of 9") with a total height of 11.5" (63% of dome height) In my case the arch starts 2.5" above the base of the oven, because the bottom brick is straight, no taper. So, the actual arch curve is only 11.5"-2.5"(brick thickness) = 9.0" in height for the inside of the arch. The outside of the arch is then 9" + 4.5"(brick thickness)= 13.5" radius of outside arch, or 27" diameter. So, pi x 27" / 2 = 42.42"
42.42/2.5" brick thickness = 16.97 bricks. My brick thickness is just slightly less than 2.5", usually 2.4375" to 2.375" and you have to have room for mortar joints. I wanted 1/8" mortar joints. If i used 18 bricks (even #) you don't have a keystone, so i went to 19 bricks for the arch. Don't count the bottom bricks, they are straight. the outside radius was 42.42/19 bricks=2.24" for each brick on the outside. the inner radius is (pi x 18")2=28.28" 28.28" / 19 bricks is 1.49" that is without room for any mortar. take 1/8"(mortar joint)/2 (bricks share mortar joint)= 1/16" from each measurement, so 2.24" -.0625" = 2.1775" round to 2.125" or 2 1/8" outer radius thickness. inside thickness becomes 1.43", round to 1.375" or 1 3/8"
is used an old piece of tile and made a template. took a couple of time to get the template close enough that it fit in correctly in the actual size drawing. I used the template to mark the face of the bricks and started cutting. I used Johns method to determine the cuts on the top and backs of the brick (not nearly as good as the teacher).
I cut that poster board (inside of arch) and glued it to my wooden arch template to guide the bricks as is set them. When you set them, alternate sides and check with level after each pair of arch bricks are set. You can make slight adjustments with mortar and your bricks wont be perfectly uniform. If one side is slightly ahead of the other find a brick that is a little thicker as you set and watch the template as you go. Use the wooden arch support to keep you vertical as you go.
Long story short-draw picture and cut bricks like picture.
Tracy

[Pompeii Nate]

Re: Texman Build

Texman,

Your arch looks great! Can you give me an idea of how much you cut off of each arch brick to make them all fit like that? I want to do something exactly like yours and John's but I have not even started yet. If I remember correctly John said he just eye-balled it but he also had some Sketchup drawings which I am sure helped. So any input and advice would be great.

Thanks,
Nate

[GianniFocaccia]

Re: Texman Build

If it's not too difficult, take out just that one adjacent brick. I used homebrew mortar, and a hand-grinder with a diamond blade made it easy to remove the mortar prior to wedging a good-sized flat screwdriver in there and twisting the offending brick loose.

Yes, I ended up cutting all four sides of each brick which meant that each one was angled, tapered, and beveled. After rounding the bottom and scalloping the top of the brick, I contoured the face both sideways and vertically.

John

[deejayoh]

Re: Texman Build

I had this same problem - a droop on one side of my dome that got "set" too much to remove. I ended up cutting a thin brick shim to go on top of it and normalize the height. I finally got the next chain in on top of this over the weekend and that approach seemed to work out just fine. I am finally over the top of the arch with my last chain and everything is nice and level all the way around.

Edit: but I will say that I am surprised how easy it is to get the bricks that are "Set" out with a well placed blow from a cold chisel. I have taken them out after ~36 hours and they still break out pretty clean. I my case I didn't notice the droop for a few days so I left it. Also - when the brick is right next to the arch you really have to knock it inside->outside, and in my case the mortar line inside the oven is pretty small. Hard to use that cold chisel without crumbling the brick.