Steel Dome Oven

[Wiley]

Re: Steel Dome Oven

Here's the latest progress: Today I stacked the stand. It took longer than I expected and alot more energy than I imagined. I will pour the infill on Thursday.

I have departed from the plans and built a "H" shaped stand with two storage areas. One will be used for wood and the other will accommodate my recently acquired proofing box for bread. See photos.

I also decided on trying something different in regards to the lintels over the entrances. Instead of angle iron and notching the blocks I am trying inverting bond beam blocks and running rebar across and down to the suppport slab. The opening isn't wide and I feel/think/hope this should work. Time will tell. Again see photo.

As always thoughts and suggestions welcomed.

Wiley

[thebadger]

Re: Steel Dome Oven

Wiley,

Looks great. Don't worry about it. Once the blocks are on you won't even notice...

I'm getting close on my oven and I'm seeing the "light" - in that I should just "worry" about things that will impact performance or be seen when the oven is finally done. For ex. I was worried that the outside of my dome brickwork was messy. I then was like "hey" no one is ever going to see it...

Keep up the great work. Looking forward to seeing your steel oven completed.

Thanks
Dick

[Wiley]

Re: Steel Dome Oven

Well so much for clear and sunny... more like light drizzel and overcast. Overcast is fine as it makes pouring concrete much easier as one does not have to fight the sun drying it out.

Anyway, off to the quarry as planned and the drizzel stopped by the time we were back. Below is a photo of 1/4 minus crushed basalt. My plan is to mix this with Fondu cement and use the mix to clad the outside of the steel dome. It certainly is less expensive than bricks. My trailer holds one cubic yd and also that is the minimum purchase/charge; the weight was 2220 lbs at a cost of $13.84 tax included. And with a yard one could build several domes.
Of course, it's only a less expensive alternative than bricks if it works. I'm thinking a mix of 1 part cement to 4 part basalt by volume. Anybody have any thoughts?

So the drizzel had stopped by the time we returned from the quarry and about 12:30 we started the pour. "We" being my wife and myself. Two hours later we were finished with the actual pour and screed and I spent 15 minutes or so troweling the surface about 2 hours later and again about an hour after that. Surface isn't perfect but level and smooth enough. Again pictures taken from upstairs bedroom window of before and after.

So depending upon conditions (if it stays overcast then sooner) I expect to be stacking block on Monday :-)

Wiley

[Wiley]

Re: Steel Dome Oven

Thank you for the kind words.

I finished the excavation for the foundation today and two pallets of Quikrete arrived this morning. More than I need but since I have a few other projects in the works I only have to pay for one delivery.

My plan is to run to the quarry tomorrow to pick up a ton (one cubic yard) of 1/4 minus crushed basalt for the cladding. This is a bit early in the process for having that onsite but my friend with the big truck that can haul my trailer is going off on vacation. And then to pour the foundation in the afternoon.

If all goes well I should be stacking block on Monday and perhaps infilling on the same day. Good weather has finally arrived... at least a few days of it. :-)

I've elected to go with a "H" shaped stand with wood storage on one side and a two drawer bread proofing box on the other. I'll take pictures and post as things progress.

Wiley

[granvillearden]

Re: Steel Dome Oven

Great Job. I am considering one like this myself.

[asudavew]

Re: Steel Dome Oven

I'm really enjoying this thread.
Great design.
I have to agree with George about the cladding.

thanks for posting

Dave

[Wiley]

Re: Steel Dome Oven

Well, I did the modification to remove the excess chimney pipe support and reassembled the unit. I also extended the chimney to 4ft. It rained last night and all this morning and so the ground was soaking.

I decided to build a second bigger fire, not a super raging fire as without the heat sink of the 3-4 inches of basalt concrete I could easily reach 1000+ F in a single spot and perhaps cause myself some unwanted problems. As it was with this little fire I got the top of the dome to 625F within about 15 minutes. The smoke problem seems to be resolved. Here's a photo taken with the fire going.

Wiley

[Wiley]

Re: Steel Dome Oven

Thanks everyone for your imput.

dmun: we added an extra short (36") piece later during the trial and did not detect any difference. We were still getting a slight amount of smoke out the front. Of course things had warmed up a bit so it wasn't a proper test although it was still only a small fire. I would like to have an igloo rather than a gable framed FWO and so keeping the chimney as short as practical is desireable, supporting 6 ft of chimney presents its own problems.

Thanks Bruce I looked into the flow rate calculator unfortunately there are so many variables such as chimney throat shape that for me experimenting seemed the easiest answer.

One thing that crossed my mind during our morning walk. (we do 2 1/2 miles every morning sun, rain, snow, whatever the weather). When I constructed the ring that holds the chimney in place on the top of the transition piece I deliberately left about a 3/16" supporting lip all around the inside. That 3/16" x 18 3/4+ inches circumference actually reduces my X-sectional flue area by about 3 1/2 square inches. The 6" chimney X-section is nominally 28.27 sq inches, that support is reducing that to less than 25 inches. I should reduce the support ring to three small protusions and so recover a majority the lost area. It's an easy enough thing to modify. If I get 3 sq inches back I'll be increasing my present flue X-section by about 12%.

Here's a photo of the lip. Thoughts? Anyone see something I'm missing?

Thanks everyone, Wiley

[brokencookie]

Re: Steel Dome Oven

Your smoke will always go from hot to cold. The larger the difference in temperature the better the draw. Somebody posted a spreadsheet that calculates chimney draw on the forum that you can use to check this. So.. Once you insulate, your oven will run hotter, creating a larger difference between the oven chamber and the outside air. Additional chimney height can also help.

Bruce

[dmun]

Re: Steel Dome Oven

I think another length of the chimney pipe would be more useful than a re-designed transition. Remember; this is all outdoors, where drafts push smoke around, and you don't have the temperature difference between outside and inside that drives fireplace draft. A whiff of smoke on startup is normal, but smoke pouring out once the fire is going strongly is not.

[Frances]

Re: Steel Dome Oven

I think a bit of smoke, specially while the fire is starting up, can be considered normal.... well, I know my oven spills quite a lot of smoke to begin with. Less would be better...

Your idea of building a larger fire sounds like a good way to go. Then you can decide whether you can live with the amount of smoke or not.

As long as the smoke stops pouring out of the front once the fire gets going properly you should be fine.

[Wiley]

Re: Steel Dome Oven

Thank you for the kind words, George. Yes, the plan is to cover the dome with aluminum foil and then 3-4" of basalt concrete (basalt 1/4 minus mixed with calcium aluminate cement) scored deeply so the expansion cracks will be somewhat controlled. The a Frax blanket and vermicrete and stucco.
I'm a bit concerned about the small amount of smoke I'm getting out the front. Is a small amount normal? I mean I see photos of ovens with significant soot staining and don't know how my loss thru the front compares (due to small test fire) a real fire. Any thoughts? Maybe I'll try a much larger fire tomorrow.
Thanks,
Wiley
Oh, and here's a picture of me :-)

[gjbingham]

Re: Steel Dome Oven

Wiley,
Very cool. A one in a million oven. I'd consider adding about 4 inches of cladding or some type of heat sink outside the dome to increase your thermal mass. That should help retain heat much better than just the metal dome alone. Insulation outside of that, a finish, and you're done!

[Wiley]

Re: Steel Dome Oven Test Fire

I've taken several photos of the intermediate steps but figure unless the oven works they are not really that valuable. So today I assembled the pieces I have built on the driveway in front of my home and had a test fire.

So lots of things were "mock-up", the bricks on the hearth are old red bricks and in order to insure some sort of air-tightness I packed sand around the outside of the dome itself. The chimney was something I found at the recycle center (see where I shop :-)

I am including a photo of the three pieces before assembly. Also I would like to know (even though the photo doesn't show it) I did get a small wisp of smoke out the front, is that common or do I need to consider rebuilding my transition piece... in this case the hoop band that connects the chimney to he FWO? Thoughts and opinions welcomed.

Wiley

[gjbingham]

Re: Steel Dome Oven

No, you're probably right. The mix sound correct. There's a latex additive for the finish coat to make it waterproof though. Shouldn't be a problem for you.