Steel Dome Oven

[Wiley]

Re: Steel Dome Oven

Bill,

Thanks for the kind words.

In retrospect the only thing I would change is to make the transition area larger (the area where the smoke leaves the oven and enters the chimney). Once hot and at temperature there is no problem but a larger transition and perhaps a larger chimney x-section (8 inch rather than the 6 inch I used) would eliminate any smoke out the front during fire up. Other than a small amount of smoke at fire up after two and a half years use I have no complaints with the WFO.

Presently I, like many, are awaiting the arrival of Spring here in the Pacific Northwest. Temperatures this morning were near freezing...what's with this weather?

With respect to my second WFO: I've managed to clear and level an area for my little FG trailer near the pond site, however, all the rain has made excavating the rest of the pond a non-starter to date. I did order and receive the EPDM liner. That's out of sequence...getting the liner before the hole is finished but the price of shipping is headed upwards. The liner came from Tennessee and the shipping alone was $935, and that was just over a month ago. Just checked and the cost to ship that same order today is $1340. Yikes!

Bests,
Wiley

[buckeyebreadman]

Re: Steel Dome Oven

Got my tank (40 incher), cut off the ends, found a split rim and am ready to get started!!

I have a question though........does your oven maintain temps long enough for Bread Baking?....some of the traditional ovens stay hot enough for Many hours.......just curious..

[Wiley]

Re: Steel Dome Oven

Buckeyebreadman,
Baking bread is no problem, I usually fire for a bit longer than I do pizza (my WFO is pizza ready in about 40 minutes from match) so something on the order of a full hour and although I haven't tried a second batch I would think that you would not have to fire much longer than that as there is plenty of retained heat at the end of baking one batch....although you would probably have to extend the length of the bake.

Since the steel conducts heat more efficiently than brick the time needed to saturate the dome is shorter. I inquired of Mklingles (the member who was doing the heat analysis of his oven) about the relatively short heat up time and here's his reply:

quote:

You are correct that steel is a much better conductor of heat than fire brick. The conductivity of steel is ~43, and firebrick is ~1.4. So, about 30x better conductor of heat!.

The steel is probably black. So, it is absorbing and re-radiating heat, not so much reflecting it. It would quickly heat through and radiate the heat into the brick and into the oven equally.

I agree with your notion that the heat spreads through the steel very quickly then radiates into the brick much more evenly. My dome clears (burns off the soot) first on the top of the oven and takes a while longer to clear down the sides.

Also that 30x greater conductivity means the steel absorbs heat from the hot gases from the fire 30x more efficiently then the brick. So you have less heat flowing up your chimney.

Cheers!

end quote.

I have had great success heating for a single bake of rolls and then when I pull the fire I save it (keeping it going in a Weber BBQ). After the rolls are baked I allow the oven some time to cool and then I put the fire back in the WFO on one side and place a pork shoulder on the other side. I place two firebricks on their long edge between then fire and the pork shoulder. The bricks were in the WFO during the fireup and left during the baking of the rolls. They form a barrier between the coals and the pork. I then place soaked wood chips on the coals and smoke the shoulder with the door open a bit to allow some air for combustion. When the pork is smoked to my liking I remove what's left of the fire and close up the oven. The next day I have wonderful pulled pork on the rolls I baked.

I will add that I have yet to build an insulated door, I'm still using the simple wooden one with the pie plate for a window I mentioned in this thread.

You should have no problem baking bread in a steel dome WFO.

Bests,
Wiley

[buckeyebreadman]

Re: Steel Dome Oven

Wiley,
couple of questions..........

I tapered the split rim to sit level with the oven. The top where it attaches to the dome is 9".
Would there be anything wrong with cutting a 8" hole and welding in a 8" (1/4" wall) pipe for the chimney?
With that said, would it be advisable/necessary to extend the transition area as you suggested?
Also, I'm using a slab of Travertine where you used granite.....any thoughts on that?
Thanks again........(I'm gonna bug you to death with questions!!!

[Wiley]

Re: Steel Dome Oven

Buckeyebreadman,
Questions are not a problem :-) I'll answer as best I can, and if I don't know an answer I will tell you that. You may wish to start your own thread but that is totally up to you.

Regarding the 8 inch pipe directly connected (as opposed to creating a transition area/volume): You spoke of 9 inches of space at the top of the rim where it joins the dome, however, what is the distance at the bottom where the rim joins the dome at the hearth? The 9 inches of space on the top of the rim with an 8 inch hole would most likely place part of the chimney opening such that a vertical door (stopping when it intersects the dome at the hearth) would not close off the whole chimney. You could get around that by making a door with a extension overhang (like a visor on a ball cap) that would close off the chimney. Insulating that overhand could probably be figured out, but a really tight fit might be more problematic. Otherwise I seen no problems with using the direct connect, the volume of the 8 inch pipe would certainly be a great deal larger than mine (area of 8 inch circle being just over 50 square inches, the exit into transition on my WFO is 27 square inches).

As for using travertine. Travertine is a calcium based mineral. It can be very beautiful but it is quite soft and quite susceptible to damage by anything acid and also it is easily stained. Dragging cast iron pots, pans and grills etc over the surface would easily leave scratches. Personally I would suggest considering something harder and more durable, but with care I'm sure one can make it work. It would probably have to be sealed more often than something like granite.

Hope this helps,
Wiley

[buckeyebreadman]

Re: Steel Dome Oven

It's actually Durango Marble.........looks a lot like travertine......my mistake.

[enz]

Re: Steel Dome Oven

On the matter of the transition into the flu pipe, I would make a nice smooth transition. I built a 40" cast refractory oven in 2006/2007 and had a the flu go straight into the overhang with no transition. It's the one thing I wish that I had done differently. Even though the flu was sized appropriately, it never drew as well as it should have and I think that's why. MTC. YMMV.

[buckeyebreadman]

Re: Steel Dome Oven

ENZ....could you elaborate a bit more on that?
what do you mean by having the flu go straight into the overhang with no transition?
more space between where the smoke leaves the oven and goes into the flu perhaps?

[Filthymutt]

Re: Steel Dome Oven

Wiley, I like your oven. And the steel dome.
Thought you might appreciate these photos.
http://http://www.fornobravo.com/forum/members/filthymutt-albums-stainless-arches.html
Not mine, they are photos from an Australian modular kit maker. I just want to do my Arch and chimney this way

[waynespizzaworld]

Re: Steel Dome Oven

Wiley do you know if these old spherical tanks can be found in both a 42" and a 46"? The reason I am asking about this size is I am thinking of using the two sizes of tanks for a two part mold on a castable project. 44" and 48" would also work I guess. Also 40" and 44" in a pinch. The idea is to have a mold that would give me room for a 2" thick cast dome.
Also would you have any ideas for locating one of these beasts. I am in the Vancouver Canada area but could travel state side to pick up if I could buy two different sized hemispheres to accommodate this project.

Thanks Wayne

[Wiley]

Re: Steel Dome Oven

Hi Wayne,
I do not know all the sizes these old tanks came in. But right now finding any suitable tank is going to be problematic. The problem seems to be the high price of scrap steel. The man from whom I traded for my tanks used to have several sitting in his yard. The story I got was that he had a contract with some scrap yards in California. Seems they were unwilling to cut them up for fear or liability. So he had a fairly steady stream of tanks which he cut in half and sold for backyard BBQs and such. That was 4 years ago. A few months back I chanced to stop by his yard in search of a set of used tires for my utility trailer. His yard was almost cleared of all the scrap metal, but there was a goodly sized hill of used tires. He told me that the price of scrap was so high it made sense to simply take the wheels off and crush the cars and send them to Seattle. From there they went to Korea or China or ? I got my tires (a nice almost new set of heavy duty tires for travel trailers and the cost was all of $5 each). Seems tires are hard to recycle and cost him money to get rid of.

I expect the situation to be similar anywhere along the West Coast, but you might try calling scrap metal dealers in Vancouver and see what they can do for you.

Bests,
Wiley

[waynespizzaworld]

Re: Steel Dome Oven

Thanks Wiley, good to know. I am a recycle yard shopper myself. Sounds like a good deal on the tires, way to go. The recycle yard I frequent rarely has any steel, they seem to mostly have aluminum. Looks like you found the components for your build at a good time. Love your oven by the way, very clever.

The photo attached is my from my last visit to the recycle yard. The guy that sold me this real, figures it is a Data real of some kind. I ran a shaft through it mounted to a 10 inch stand with a wheel bearing in between for some nice spinning action and faced the center hub with some copper. I use it as a giant Lazy Susan for pizza toppings. 4 bigger bowls and 4 smaller to hold grilled veggies, cheese, flour, corn meal etc. Works real nice and I only paid 10 dollars for it. Feels good to get a bargain and then have some fun turning it into something else! When its not dispensing food I just hang it on the wall as decor.

[Ellisco1]

Re: Steel Dome Oven

Wiley,
Your build thread is an inspiration and I am starting on my own. One question , how did you get the Kaowool to stay in place while you were working on the cage? I was thinking of sticking some wires into the wet mortar then punching those through the insulation and bending them over but then I have never done this before.

[Wiley]

Re: Steel Dome Oven

Ellisco1,

Due to a computer virus several years back I lost a great many of the photos I took during construction. A good reason to back up important files which actually I did, however, I have miss-placed the dvd with the backed up photos. So it is as if they were same as lost except that there is a hope that someday the disc will turn up :-|

However, in answering your question, if one looks closely at this photo:
http://www.fornobravo.com/forum/atta...-side-view.jpg
On the insulation layer about one foot up from the bottom, one can see the indent of a line that originally ran all the way around the WFO. This was from a piece of kevlar measuring tape I re-purposed.* Now there are many ways to cover a dome with insulation. Since my kaowool was about 4 ft wide, the method I selected was to wrap the insulation around the dome so that it was standing on edge forming a sort of cylinder. The Kevlar tape held it against the dome and allowed the cylinder to stand upright while I cut slits down from the top. These slits allowed me to fold the insulation down onto the dome and allowed the extra material to lie over the adjacent piece. Extra pieces were laid on and over the top and held the whole insulation fold-up/layup together. There are two layers done this way and the folds are laid out so the overall thickness of insulation is fairly uniform and increases as one measures up the outside of the dome.

I originally planned on leaving the kevlar tape in place until I placed the birdcage and started filling the loose vermiculite. At that point I had planned to cut the tape and tuck it in and forget about it, (and it is in place around the inner layer). However, in placing the birdcage it became necessary to release the kevlar tape around the outer layer. When I released it I found that the insulation had assumed the desired shape and had no inclination to either slide off or fall away from the dome. The top was held by the pieces laid across which kept it from sliding. And it would appear that in the time between placing the insulation and the birdcage the insulation had formed to the dome and stuck/adhered a bit to the inner layer of insulation. Since it was holding I saw no need to replace it and so didn't. Once the space between the insulation and the birdcage was filled with loose vermiculite, it held the insulation in place and in contact with the refractory (or at least the outer shell never has gotten hot so one would assume it still is holding it in place).

Kelvar tape is not that uncommon, it's also used as pull rope to pull wire thru conduit. But as it turned out I really don't think it is needed in the method I used. One would still need to hold the layer during assembly but that could be done with wire and after the second layer is placed and allowed to settle in you could carefully cut one end and pull out the inner wire. The outer wire could be left or removed.

Hope this helps,

Wiley


*It was originally a measuring tape that had been damaged in it's first few feet, someone had balled the whole mess up and tossed it. I found it along side the road on one of my walks. I knew what it was and that kevlar is quite heat resistant (check the material used in a OveGlove and you will see it's made in part of kevlar) and being a scrounge at heart, I gladly picked it up. Once you see it it is easy to identify, sort of golden color, very strong and heat resistant.

[buckeyebreadman]

Re: Steel Dome Oven

Wiley, I hope you're still up on this page. I'm all the way up to the insulating layer (only two years in the making here) and was wondering.....you have, in post #41 a thinner layer of firebrick and then the oven floor on top of that. For the purpose of keeping the floor level, would a layer of soapstone suffice for that thinner firebrick layer? I'm not sure my vermiculite insulating layer is perfectly level....