dmun's 36" geodesic oven

[dmun]

Originally Posted by maver

David how high is your oven opening relative to dome height?

The dome height is 18 1/4, the door height is 13 1/4, the door width at the bottom is 18 1/4. Those are all one quarter inch bigger than planned, mortar creep no doubt.

Originally Posted by maver

James - does cladding provide stability for the dome joints? Shouldn't the similar thermal properties of the refractory mortar and firebrick align in a well constructed dome as David's appears to be (with very tight joints)? Thes refractory materials shrink with heat, right?

I'm not too woried about the stability of the thing: there's not much mortar, and it's closely matched to the linear expansion of the firebrick. I've been careful to create slip planes between firebrick and other materials, and the exterior part of the masonry chimney will be independantly supported from the firebrick liner. I notice that when I hit the dome, it rings like a bell, sort of. I think it's really sound.

Just as a side note, when I set the inner, refractory, arch, I used the last of my original fifty pound bag of Heat-stop refractory mortar. Not too bad for an oven, an entry, a fireplace, and a rumford throat. On the other hand I just bought my third ten inch tile saw blade.

[christo]

Still using and liking the Brickie?

[dmun]

Originally Posted by christo

Still using and liking the Brickie?

The Bricky system is great, and it would be even better if I were building a freestanding oven, because one of the things it doesn't do is lay a line of mortar up to an obstruction. Using the bricky emphasizes that you are not gluing bricks or blocks together with mud, but that you are building concrete objects to fit between your masonry units. Everything that comes with the Bricky is great. The round nose trowel is perfect for mixing, moving, and applying mortar. The jigs for applying mortar to the end of bricks and 4" blocks make the worst part of the job easy. Once you are used to using the pointing tool, it lets you finish the joints smoothly. (You use it twice, once to push the mortar in place when it's wet, and again to smooth things out when it's a bit dryer.) Even the video is useful: it shows you techniques that masons learn by seeing someone else do it. Do you know you pick up mortar with the bottom of the trowel? The only thing I haven't used is what they call the mason's mate, a string guide for long walls.

If I were building a freestanding oven, I'd make an exterior wall of brick and and interior wall of half thickness blocks inside the wood storage area separated by a half-brick (4") space. The inner blocks could support the hearth slab , and the outer wall be most of the form for same. All I can say of the Bricky is that it makes bad bricklayers good, and good ones fast.

[james]

There is a lot to like about the enclosure design -- the oven construction aside. I agree that the slate and brick work well together, and the repeating arch, both in material and curvature with the oven opening and the storage area below looks nice. The slate baseboards on the foundation corners looks very nice. I like the cantilevered landing (I am coming to like that design), and the slate threshhold into the storage area is clean and elegant. And I like the larger keystone at the top center of the oven arch. All really nice. Great conception, great details, great execution.

Maver, on the oven itself, if David can build the dome to +/- 1/4" from his origional cad drawings, I am just going to sit back and watch it go up. Like a fine Swiss watch. We will all await the first firings with anticipation -- and see how she cooks!

James

[dmun]

We've had an amazing run of great weather these past few weeks, but it's time to close up the workshop for the winter with more than a draped tarp. I have to heat this space, after all. I started by filling the old window hole with glass blocks I picked up from an eBay vendor. You'll notice they didn't quite fit, so I had room for a slate sill to match the one under the wood storage door.



This dark inside view doesn't show much, but you can see that the rustic slate sill is deep enough to cover the edge of the concrete blocks. I'll finish the top and sides of the exposed block with concrete.



As a side note, glass block aren't easy to lay. They are matted on the edge, but the mortar doesn't really stick to them. Since they are not porous like masonry, the mortar doesn't have that initial set up within a few minutes. The whole thing stays wobbly until the mortar sets up by itself. Also, since light shines through, every slight difference in mortar thickness is really obvious. On the other hand, it's really easy to clean the mortar off them, and you have to because it slides all over the surface when you are trying to get them in place.

[dmun]

Here's a view of the framework of the temporary roof I built out of used lumber:



This got covered by some used plywood and a couple of layers of tar paper.



This just sits on top of my structure. There is a bag of used insulation stuffed in the future flue opening in the front of the oven.



Not much to look at, but it will keep some wind and wet out of the structure until the end of winter.

I'm thinking that this is a good stopping point, and I'll start a new thread in "design styles, chimneys and finish" when work resumes, and leave the pompeii section to people who are in the oven building stage of their projects.

[edschmidt]

I hope people are still checking in. I just joined this forum after being on the yahoo brick group for 1 year. Anyway I am a kindered spirit on the geodesic oven design. I designed mine on the computer about a year ago and started casting the triangles out of 2300deg. castable refractory. My mindset was that large castable refractory ovens crack, so if I cast the smaller 4" thick triangle and not mortar them together that they could expand and contract with the heating cycle without cracking. I assembled the triangles, added a building paper slip layer (Im sure burned out long ago. The entire dome I then covered with 4" of reinforced concrete. I have been firing it at least weekly since april with absolutely no cracking and 12 hours after the fire is removed the oven is still in the 270-300deg. range. The entire oven including base, vermiculite and roof so far has cost me $500.I will try to post some construction photo's if I can figure out how.

[Amishcountry]

Ed, Please, Please, Please.....give us more info on your oven.

I am planning a garden and pizza oven for a spring summer project. I have been tossing the pro's and con's of various oven designs back and forth.

"Dmun's" g-dome has intrigued me, but I doubt I could do all the brick cutting, as he is truly a skilled artisan. Dmun's project is truly a benchmark for inspiration.

Through research, I have found various threads stating pro's and con's about trying to cast your own oven parts.

However, none have mentioned casting small parts(the triangles), as you have successfully done, with your G-dome. Sounds like you have come up with a winner!

Can you share more about the casting mix you used for the parts, and any specifics, plans, measurements etc....for the mold to make the triangles.

Thanx for sharing, I'm sure your post will generate a tremendous amount of interest.

Do you have website, blog etc...for more info??

[edschmidt]

I dont have a blog, or website, but I did take a decent amount of pics during the constructions phase. Did the pics that I posted come through? I cant view them on my computer. Anyway I could not find Aluminum silicate cement where Here in Grand Rapids MI (but wasnt sure where to look) So I looked on e-bay and found a company which sells pre-mix castable refractory, and the company happened to be 15 min. from my house. It was designed to be used for melting metal so its obviously plenty overkill, but I prefer that (I also got the firebricks for the hearth from them which are super heavyduty(2600 deg.). Anyway It took 10 bags of castable at $20 each (50#bags) to cast the 4" thick dome. Including the outside layer of thermal mass I have 8" of Mass in the dome. For the hearth I poured the concrete slab over my blockwork with a slip layer (aluminum to seperate slab from blocks) then 4" of vermic/cement mix, 2" of sand(for additional mass) and laid the firebricks on top of that. I know that most people use the slab as part of the thermal mass, but because I was not interested in suspending the slab, And I didnt the heat to weaken the slab which is responsible for holding the entire oven up, I decided to put the thermal break between the hearth and the structual cement Plus sand is cheap and an effective thermal mass.
I think Im getting a little long winded, Let me know if the pics came through, if not I will re-post. P.S. where are you located?
Sincerely
Eddie Schmidt

[edschmidt]

A couple more things I thought I would point out, Im not sure if dmun square cut or angle cut the bricks(from outside of oven to inside of oven) but the triangles that I cast were larger on the outside of the dome than the inside which is how I eliminated the need for mortar, and allowed the dome to be selfsupporting without it. In the geodesic pic. you might notice the newspaper holding the dome up. What I did is take my sons large 48" inflatable kick ball and inflate it to 36", cover it with about 10 layers of paper mache' and use that as the temporary form to hold up the oven. The oven becomes self supporting once the final brick is put in. I then just pulled the form out through the oven door.
Eddie Schmidt