dmun's 36" geodesic oven

[maver]

You have to be careful in planning to be clear why we would want to reduce mortar in dome construction. David has expressly indicated his reason was due to the cost of mortar used. With his excellent planning he was able to engineer a dome that had low material costs - and probably not a big difference in labor from my dome (or any other made from splits). I tried to reduce mortar (primarily in the oven face) by alternating half bricks with trapezoidal cut bricks - didn't measure, just pieced them together with some good estimates of the angles needed. Usually any miscuts were incorporated into the dome for upper rings as the angles constantly changed. While an oven built with less mortar is theoretically more stable, with modern refractory mortars or even the pompeii home mix mortar with fireclay I doubt it is likely to become an issue for a home oven.

I like David's design for the thinness of the dome - I'm anxious for weather to improve in the Northeast enough for David to cure his oven and report back on heat up times (probably the sixth full firing before the oven will hit it's stride). How's the weather David?

[edschmidt]

The reason I would prefer to reduce the mortar is because the refractory sales people I have talked to have expressly stated that large areas of mortar are inharently unstable. He told me that the maximum I would want to any mortar is 1/8" thick and the thinner the better. Granted he is selling refractory products for use in kilns, blast furnaces, etc. But with that said the firebrick is a pressed and fired ceramic and therefore very stable structure. Mixtures of fireclay,sand,cement are not (cement degrades, fireclay increases strength as heated but not fully until cone 5, approx 2000deg.)He also didnt give have alot of faith in heatstop. I know the real world experience is that in our applications these products work, but the 2500deg pre-mixed airdry mortar he sells is .50cents a pound so why not try for an oven that could double as a blast furnace if the need came up.

One more thought since im obsecing about the tapered oven, I would start the base as a square, and the corners could be alternately overlapped like normal brickwork right? that way I would only have to cut 2 bricks per course, plus gain the stability inharent in an overlapping structure right? Am I missing something or would this work smoothly?

[edschmidt]

One more thing, durring the brief thaw here in MI, I did a little more work to the oven exterior. I went back and forth alot on the roof materials and decided I just wanted get something more permanent than the Ice and water shield which has graced it for over a year and bent up a standing seam aluminum roof. My wife wasnt impressed, until I told her I can paint it. Im also contemplating using granite on the face (now white).

[RTflorida]

very nice. personally, I love the "tin" roof. As for a granite front, it would really dress it up, upscale - yet keeping with your stone theme. very nice

[need2retire]

I've been reading this thread and forum over and over again, so I'm starting to understand a little more (I think ). I'm still sticking to the "traditional" way of building the oven because I think it will be more forgiving for a beginner like myself

I've also convinced myself that cutting wedges on the two sides are easier (as apposed to my previous post) than doing the top/bottom sides. I "THINK" I have a way of cutting wedges without the need of calculating the wedge angle and/or radius for each level. I've already test that, but only on a two-dimensional plane.

I think I can figure out the cut for wedges on the top/bottom side as I progress on each level. However, the bottom side get harder because I need an additional "curve" shaped cut to fit the curvature of the ring ... to eliminate any space between bricks. Anyone tried this?

So, I do have 1 crazy question. Does anyone know where I can get styrelfome block for cheap? I'm thinking of building a dome out of styrelfoam block 1st. Why you may ask?

1) For me, building from foam block is a good way to practice ... and mistakes are very easy to fix.
2) When I'm done, I can take the foam pieces apart and use it as a templet to cut my real brick. Hopefully this way I can get a near perfect fit. I guess if you're building oven professionally, you'd have a permanent templet to use over and over again.
3) I can slice the foam dome to pieces and use it as a form to do castable brick.