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-   -   #2 Taper-Brick Arch (http://www.fornobravo.com/forum/f8/2-taper-brick-arch-7099.html)

timo 06-26-2009 05:08 AM

#2 Taper-Brick Arch
 
Here's the #2 taper-brick arch. It is 8 1/2" high and 15 1/4" wide. If I raise the arch with a standard firebrick and a split I will hit a perfect 12 1/4" height for the opening. 63% for a 39" oven is 12.285"

I have two questions:
#1. I want mortar to be as thin as possible to keep the dimensions. How thin can I wipe the mortar in and still make a good bond?

#2. The 15 1/4" width is a bit less than what I was hoping for. The plans call for an 18-19" opening width. Should I fuss with the arch and add a wider keystone at the top, or should I grab the perfect arch width and call it a day?http://ovenblog.timttech.com/now/gal...d/IMG_6776.jpg

Lars brought up a good comment about workability. I made a mock up duct tape peel and took a 13" pizza pan and tried it out.
http://ovenblog.timttech.com/now/gal...d/IMG_6777.jpg Seems to me to be enough room. Yes it's tight, but I think manageable. How do I know, I've never cooked a pizza in a brick oven ;)
I love bread too so maybe better with smaller opening to retain heat. Does a smaller opening retain that much more heat?
Cast your vote :)

Lars 06-26-2009 06:08 AM

Re: #2 Taper-Brick Arch
 
1 Attachment(s)
If it was me, I would be more concerned about the restricted opening, and I would widen it to at least 19" . There's a lot of reaching into this oven to manage fire, bake a pizza, clean out ashes, etc. The trade off between heat loss and ease of use is the question... not really the exact 'look' of the arch. But, although the tapered bricks are beautiful, they do not make the preferred opening width. There will be MANY ways to make the arch, not only more interesting looking, but more functional as well.

My two cents...

altamont 06-26-2009 06:41 AM

Re: #2 Taper-Brick Arch
 
re: How thin the mortar joint....
If you are using a refractory mortar - one premixed in a can made specifically for laying firebrick - we used to have a good 'rule of thumb' for diluting with water for building a furnace.
Basically, water would be slowly added and mixed until a 9" straight would expose 1" when floated. This 1" is with the 9" x 4 1/2" surface facing up, parallel to the surface of the mortar. A 9" straight is 9 x 4 1/2 x 2 1/2 inches. So 1 1/2 inches would be submerged with 1" out of the mortar. Add any more water and it would be too much. That would give a pretty consistent 1/32" mortar joint between brick. If in doubt don't dilute that far.
Again, that rule of thumb applies to premixed mortars that contain everything needed including including sodium-silicate which bonds the brick togeather at ambient temperatures when it dries.
---------------
regarding arch - I am still jealous that you were able to source Arch brick! You should be able to throw in combinations of those along with 9" straights or splits to widen and not degrade the stability of the arch much. The mortar, if a thin joint, should hold everything really well once it sets.

I've just started breaking ground for my oven. After a lot of consideration, I am leaning towards having my 'inner arch' fairly wide and watch the height as you are doing (the ratio between the inside height and the arch height). But i am then considering making my outer arch on the exterior face an inch or two lower and a little narrower. Basically making a 'smoke chamber' in hopes of keeping the combustion gases going up the stack and not out the main opening. At worst I might still get smoke coming out rather than up but there again, I might be able to reduce that and keep the exterior surface a little cleaner over time...

Dino_Pizza 06-26-2009 07:46 AM

Re: #2 Taper-Brick Arch
 
Your picture proves you can slide a pizza peel in and out but you've also got to manage the fire: stack wood, move it around, argue with a piece or two about how it should burn, where it should be... and your 39" diameter will make you want to put a couple things in there at a time. So I say widen it to 19".

Also, I THINK you can go really thin on the mortar if you soak your bricks in water really well since they will absorb the mortar. I have some really thin 1/32 joints with both Refmix and home made and they hold great.

Nice job timo on the mock-up. The arch is really nice but I bet you can widen it gracefully too and still have it look nice. Keep up the good work, Dino

sjmeff 06-26-2009 08:24 AM

Re: #2 Taper-Brick Arch
 
I tapered my bricks using the Angle-Izer & the HF saw, and although not as clean as pre-tapered bricks, I was able to create the dimensions I wanted. Just thought I'd throw that out as an option. I'm about to do my outer arch using the same method. Here are my arch photos including the Angle-Izer:
PhotoPlog - Uploads Posted By sjmeff

Regarding mortar size, have you looked at carloswlkr's arch? He used tapered bricks and what looks to be really thin mortared joints:
PhotoPlog - Uploads Posted By carloswlkr

S

dmun 06-26-2009 09:04 AM

Re: #2 Taper-Brick Arch
 
Alternating angled and plain bricks will stretch out your arch if that's what you want.

For this use, at least, i would spring for a proper dry refractory mortar mix, like heatstop or refmix, they apply in super thin layers, spread like peanut butter, and dry rock hard.

Lars 06-26-2009 02:28 PM

Re: #2 Taper-Brick Arch
 
Timo,
Did you check out my drawing of possibilities. ( see my first post)

My arches were chisel cut and, really , once this thing goes together, you will really not see that first smoky reveal arch.

Mine was actually only 2.5" thick. I really like the way the angled cut bricks form an arch or a chain so perfectly. I was not terribly concerned about mortar joint widths, but, in fact, I think the slightly rough surface probably has a better physical connection for mortar.


There are two things I would have done differently with my arches. One, I would have put a higher keystone in the first arch, so smoke might be more channeled to the middle of the vent. Secondly, I would have made my vent opening span the entire landing. I may get out a jackhammer yet.


Lars.

DrakeRemoray 06-26-2009 02:43 PM

Re: #2 Taper-Brick Arch
 
Wider wider wider!

You need to be able to put a turkey in a big roasting pan in there.

You may need to be able to get into the oven to point some mortar in.

Wider!

Drake

timo 07-07-2009 09:01 PM

Re: #2 Taper-Brick Arch
 
Just thought I'd update the arch with the taper brick. The final arch is 12 1/2" high by 17 1/2" wide. I was able to tap the keystone in and remove the forms after an hour. After four days I was able to stand on it. I will probably stretch the outer arch with some straights. Thanks for the input on the arches :)


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