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  • firebug
    replied
    Re: Steel Dome Oven

    Hey Wiley

    Well what a journey and I'm not even close to done,the trailer is done with the oven stand built on to it. I have two questions ,if you would be so kind.

    1.My oven will be big about 55 inches inside(wide) by 70 inches inside(long) my sides will be about 12 inches tall then arch up to the center of the vault another 14 inches.total height 26 inches.is this formula correct? I know the door height should be 63%of overall oven height but I'm not sure about the rest.

    2.what would be a good way to add heat sink over my steel vault,I was going to use sand but thats not an option for me anymore,what would be typical cost wize in doing this?

    Thank you for all your help.

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  • heliman
    replied
    Re: Steel Dome Oven

    Oh sorry Wiley my apologies... I was directed to your post from another thread that focussed on your build so I think I may have confused the progress of the other WFO project with yours.

    Rossco

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  • Wiley
    replied
    Re: Steel Dome Oven

    Hi Rossco,
    Sorry I don't understand. I have been cooking for over a year in the WFO. My patio and well, my home is constantly being reinvented. Spaces change as uses and needs change. Still working on the patio, and lots other reinvented spaces around here.

    Bests,
    Wiley

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  • heliman
    replied
    Re: Steel Dome Oven

    Hi Wiley - thanks for clarifying that for me.

    Good idea to go with nature - the redish colour makes it nice and earthy which I guess is the message which WFOs in general are trying to send out.

    Any date firmed up for the big launching of the oven? I take it that there wouldn't be much "curing" involved with a metal oven.

    Rossco

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  • Wiley
    replied
    Re: Steel Dome Oven

    Hi Rossco,
    Save for the incident I mentioned in post 149 regarding speckling when I sprayed water straight against the steel dome at temperature to create steam, I have not had issues or problems with regards to rust.

    All that being said I have also stuck with red /brown/rust colors; anyone who has seen a wood boat that was fastened with steel fasteners knows the familiar rust staining. It doesn't take much in the way of iron particles to cause noticable staining. I chose to embrace the color scheme rather than fight it ("it" being the inevitable rust staining). I would certainly not suggest or encourage anyone to build a steel dome WFO with a hope of having a light colored or white entrance area. The rest of the dome it shouldn't matter. And on the other side, there are alot of steel boat owners who manage to maintain a white colored hull. All depends on the amount of work one wants to make for themselves.

    As for major degradation or deterioration, we burn our paper trash in a open ended 55 gallon steel barrel. Like the familiar soda cans oven the years these steel drums have also undergone a thinning of wall thickness. Even so without any care and with both sides exposed to the elements we get over four years of use before the barrels need replacing. Given the thickness and that only one side is exposed to the rigors of the fire...exposure I expect my 5/16 inch thick dome to easily outlast me and most likely my children. But so far I have not had any incidence of "rust in my pizza".

    Aside: We have grave sites on island and expect (and hope) that this is our "last stand". So unlike some statistical average homeowner who moves every seven years or some such nonsense.... we are here and here we happily be :-)

    Bests,

    Wiley

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  • heliman
    replied
    Re: Steel Dome Oven

    This is an amazing build - seems like there are some "ready made" WFOs lurking in the local scrap yard...

    One question though - would rust not be a problem given the high temps and moisture involved?? (apologies if this has been asked already).

    Rossco

    Leave a comment:


  • propane man
    replied
    Re: Steel Dome Oven

    Very interesting post. I have been thinking about making a WFO out of the head of an lp tank as well. I have a few ideas and your project seems to have turned out quite well. I have only been contemplating this for a few days and figured someone else must have done this by now. I googled it up and found your post, nice work.
    I have pretty good access to old tanks & have a few projects in mind, I will post more details later, I will probably need some advice as things progress.

    Leave a comment:


  • waynebergman
    replied
    Re: Steel Dome Oven

    Hi Wiley....thanks again for your help. Good point on the fitment of castable pieces to the dome. Thought I would send you the info on the Moldit-x. The link below gives the specs on it. The link is from a site I am not familiar with but found it on a web search. I had bought this mortar from Fairey & Co in BC Canada. Not sure who else sells it but sold in small quantites its bagged and labeled labeled Devil's Puddy, it is super expensive. These are like one pound bags for about 6 dollars or something. I found out the Moldit-x was the same thing as the devils putty but way cheaper in the 55 lb bags. Not sure how the prices are in the states on this product but up here the Moldit-x will be about 40% cheaper than the fondu.
    http://www.maxrefractory.ca/images/p...11/molditX.jpg

    Leave a comment:


  • Wiley
    replied
    Re: Steel Dome Oven

    Wayne,
    I think broken up pieces of firebrick would be comparable to the crushed basalt. Rado uses it in his homemade concrete mix if I remember right. The advantage I found in using straight 1/4 minus crushed basalt was that all I had to add was the cement. The proportion of fines to coarse was such that the finished material created was dense and worked easily. I will look into this "Devil's Putty", it sounds interesting.

    As for making a mold for creating the separate and expandable heatsink on the outside of the dome: Although the domes look very symetrical I suspect they are not perfect spheres/hemispheres and placing a section anywhere other than where it was cast would most likely not allow as close a fit as a section cast over the area where it will reside. Don't know if that is clear. If there was a slight dent the piece cast over the dent would accommodate the dent and fit well, however, the piece wouldn't fit as well elsewhere on the dome.

    Anyway, I found casting shaping the concrete a fairly easy process save that one had to work fairly fast. At the end of each section I was forming I placed a folded up piece of aluminum foil to form a parting surface so that the next section could closely join the previous yet be separate for expansion purposes. That the sections weren't perfect geometric shapes was less of an issue although I tried my best to keep them as uniform in size and shape as I could.

    Leave a comment:


  • waynebergman
    replied
    Re: Steel Dome Oven

    Thanks Wiley, this has helped a lot. I will look into tanks in the area here and proceed with design ideas. I will post some drawings for feedback on a new thread when I get closer to starting the project.
    In my area, Vancouver Canada what I would propably go with to act as your fondu and basalt is a product I used in my last oven called "Moldit-X", it is also sold as "Devils Puddy" but much cheaper in the bigger bags where it is called "Moldit-X". It is good for filling large gaps and the folks that sell it say it would as your fondu. It is fairly reasonable at $30.00 for a 55 lb bag. It doesn't set up as fast as the fondu but nice to work with. I wonder if mixing into the mortar a bunch of busted up fire bricks into the mix would work as the basalt did for you. Do you have a feel for how the fire brick would compare to the basalt in an application like this?
    Also wondering about making up a couple of molds to hold a pour of the above to make components like dmuns geo dome. These pieces could kind of float over the steel dome for expansion issues. The dome itself could be the underside of mold while making these components. Then insulate. I am a ways off for staring this project but thinking of different ways tackle it.....wayne

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  • Wiley
    replied
    Re: Steel Dome Oven

    Hi Wayne,
    Thanks for the kind words on my little thread. I'll try to address your questions in order.

    11. Have you used a fire brick oven to compare with yours to get a feel for pros and cons with going with a steel dome?

    I have not had benefit of the experience of using a brick dome similar to the one in the Forno Bravo plans. I have had hands on experience both with a commercial WFO (Woodstone 60 inch) and neighbors cob ovens. I have also had some small experience watching others using a very large WFO which was quite primitive by the standards we are building today. IMHO a WFO is basically a hole in some sort of heat holding non combustable medium in which a fire is built and food cooked either with the direct heat or with the retained heat to the fire. Beyond that basic one has alot of room to be creative and be as high or low tech as one desires or is able to achieve due to contraints of locale or pocketbook or ability. One thing I really enjoy about Forno Bravo Forum is the lack of people who are zealots/fanatics in what qualifies as a WFO. I really enjoy the diversity of WFO's represented. It would appear that each WFO is a bit of an individual, and how two identical WFOs act/perform can be dramtically altered by something as simple as orientation to prevailing wind. I am a bit amazed that no one else seems to be able to make or has a WFO that "pants". It's alive!

    As for cons of the steel dome: biggest I've encountered was once in order to make steam for bread I tried spraying water against the dome. I ended up with a batch of lightly speckled bread. Sprecked with what appeared to be rust spots. After the oven had cooled I ran my hand over the interior surface and the surface had no loose rust. I suspect the rust came from some sort of fairly intantaneous reaction of the water with the super hot steel. Ever since that experience I have achieved the needed steam by spraying water into a cast iron pan which I heat right along with the firing of the WFO. Spraying water upon the brick hearth or a dome I think is asking for potential problems with spalling and degradation of the surface...I could be wrong there may be no ill effects of doing so but I won't chance it with my brick hearth.

    Other than that I have no problems. I find that I can be fairly vigorous with cleaning out the coals and ashes with my rake. Scraping along the dome and getting out as much as possible. This is something I would not recommend with a cob WFO and suspect one needs to be gentler than I am with bricks as well.

    As for the a large pro I don't have any anxiety regarding cracks. I read how some are disheartened when their creation ends up with crack(s). Cracks seem inevitable or at least very common with a brick WFO and it is rare to find any WFO of antiquity without repairs. Ovens of antiquity were built with poorer materials than are available today and were used much more frequently so any direct comparison is hard to support. Cob WFOs are by their nature ephemeral, and a bit more delicate, if they meet ones needs then I think they are fine.

    2.I will ask our local propane dealer if they have any old tanks....how much should I expect to pay for a 36" or 40 " diam tank?

    Price of a decommissioned tank would vary with locale and condition. In conjunction with your question regarding cutting a tank our local scrap metal dealer has a contract with several propane companies in California to recycle their old decommissioned tanks. It seems from what he told me that the liability issue was too great for them and so they were willing to pay to have them hauled to our local guy and pay him to take them. He won all ways, paid to transport, paid to take and then sold the scrap when finished. So finding a decommissioned tank in California might prove somewhat of a problem. I would suggest being creative in your search, Craigs List and scrap metal dealers, posting at the "wanted" ad your local Grange Hall, farm feed supplier etc. Get creative and I wouldn't be surprised that you find one or more at a acceptable price.

    3.I am on the Sunshine Coast up here in Canada and don't see spherical shaped tanks they are more like giant hot dogs....I guess I could use the two ends and recycle the middle part. Are the spherical shaped tanks that common?

    The sperical tanks are old school being built mainly right after WW2. Cylinderical tanks will work just as well and you might find a decommissioned one with elliptical ends. These are beingcoming more common and would be a very nice way of making a low vault WFO. As for recycling the center part, cut it into foot or so long sections (called "pups" in pipeline speak) and give them to your neighbors for fire rings or sell them.

    4.I have a cutting torch with my welding kit....I would probably cut it open with this. Is there anything I should be thinking about saftey wise before cutting this open because of the tank being at one time filled with propane?

    People watch too much TV. Yes, you can blow yourself up although I think you would have to be unusually unlucky or plain stupid. I have watched the guy at our local yard cut up an old tank (I happened to be there when he was doing so..just lucky to get to witness the final act to his process). His process was simple (although don't pass it on to the people in California or his tank deal might dry up): Hopefully the tank will read empty on the guage otherwise you will have to connect up your BBQ and use up remaining propane. Open the tank and allow whatever residual gas is left in the tank to vent off. Leaving the valve in the open postion, the day after the tank has stopped discharging thru the valve use a pipe wrench and unscrew and remove the valve. Leave the tank open for a couple of days. And what happens next I witnessed: Walk up to the tank with a lit torch and pass it over the top where the valve screwed in. Nothing happens. I asked him if he ever had anything happen when he did that and he said once there was a slight pop.

    OK, so here is something else important: Propane is odorless so to make it detectable it is scented. The scent is a fliud which is not as volatile as propane and over years it can settle out of the fluid propane. Once the propane is gone the scent can remain as a fluid in the bottom of the tank. If one carelessly upturns a tank and the scent spills on the ground the spot where it spilled will smell like a propane leak for a very very long time. Same for getting it on your clothes. Nasty stuff, although one's mind runs to all sort of creative uses for such (all of which would get one in deep trouble with the powers that be).

    So the usual disclaimers: don't do this at home, your mileage may vary, those doing this are trained professionals, do not attempt without consulting your physician etc etc. Do what seems logical to you, if filling the tank with water seems like a good idea then do that (although how you are going to move and deal with 500+ gallons of "contaminated water" is another issue). Place a air hose connected to your compressor and let it blow air into the tank for several hours, drop a couple of pounds of chipped dry ice into the vented tank. Lots of ways to get to the end result. Just remember the tank is much more dangerous with a couple pounds of propane in it than at any other time.

    Hope this has helped, use your head and you shouldn't have any problems,
    Wiley

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  • ThisOldGarageNJ
    replied
    Re: Steel Dome Oven

    4.I have a cutting torch with my welding kit....I would probably cut it open with this. Is there anything I should be thinking about saftey wise before cutting this open because of the tank being at one time filled with propane
    I have done this with a 20 gallon tank... this is how i did it..

    1. let it sit in the sun for a few days with the valve open (this is supposed to purge any gas)
    2. I removed the valve and filled it with water and drained making sure aany gas was pushed out by the water.
    3. I cut mine using a 4" cutting disc on a grinder, Only because this is what i had available

    just be careful... obviously

    Mark

    Leave a comment:


  • JoeyVelderrain
    replied
    Re: Steel Dome Oven

    Originally posted by waynebergman View Post
    I have a cutting torch with my welding kit....I would probably cut it open with this. Is there anything I should be thinking about saftey wise before cutting this open because of the tank being at one time filled with propane?

    Thanks Wayne....Garden Bay BC
    OMG !! NOOOOOO!!!!!
    Last edited by JoeyVelderrain; 12-20-2009, 08:51 PM.

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  • waynebergman
    replied
    Re: Steel Dome Oven

    Wiley....thanks for you postings. Enjoyed looking at your pictures and detailed explainations of how and why things are working for you. I am currently planing on building another oven for resale. I may want to build what I can in my garage and assemble on site for others. I have an oxy/ace welder and have an interest in things built out of steel. I may want to build my next oven fashioned after yours or perhaps a hybrid. Brick dome with a steel fabricated entrance, vent, and stack.
    Couple of questions I have for you......
    1. Have you used a fire brick oven to compare with yours to get a feel for pros and cons with going with a steel dome?
    2.I will ask our local propane dealer if they have any old tanks....how much should I expect to pay for a 36" or 40 " diam tank?
    3.I am on the Sunshine Coast up here in Canada and don't see spherical shaped tanks they are more like giant hot dogs....I guess I could use the two ends and recycle the middle part. Are the spherical shaped tanks that common?
    4.I have a cutting torch with my welding kit....I would probably cut it open with this. Is there anything I should be thinking about saftey wise before cutting this open because of the tank being at one time filled with propane?

    Thanks Wayne....Garden Bay BC

    Leave a comment:


  • Wiley
    replied
    Re: Steel Dome Oven

    Hi Randall,
    The thermal mass in my WFO consists of the steel inner dome and the calcium aluminate/basalt concrete. Outside the basalt concrete is the ceramic kaowool insulation and outside of that is loose vermiculite (contained by the window screen then stucco). I didn't use perlite as I prefer working with vermiculite...I find it less irritating to my skin. But as for insulating properties it's pretty much a loss up between which is better. By using it as dry fill I have (hopefully) made best use of the insulating properties, anything which has cement as a binder would, I think, be less insulating as the cement binder would have poorer insulating properties than a simple void between the particles.

    I think one would be pretty safe in saying that any mixture with perlite or vermiculite is going to fall under the heading of insulating rather than acting as a heat sink.

    I might be mis-reading what you said but it would appear that you are going to try close fitting one steel dome over another. While I suppose this could be done I would think that there would be problems with differential expansion between the two domes as intimate contact between the two would be hard to achieve. I might be wrong in this but I am under the impression that heat transmission is better from contact as opposed to transmission by radiation. If there is any void between the two shells heat transmission would vary between where the shells are in contact and where they are not and this might prove problematic. IMHO I would think a dome with a refractory applied over would have less chance of problems in this regard.

    The steel dome in my oven serves several purposes: it maintains the shape structually; it is damage resistant; and because steel transmits heat better than brick any point where heat is applied (say where flames lick the surface) the heat is spread out thru the better conductivity of the steel to heat a greater surface of the underlying refractory concrete. This is only important, I think/suspect, during fire up; once at temperature and the refractory is soaked/saturated there is probably mute difference between straight brick and a steel lined refractory. I have no empirical data to prove this, it simply makes sense to me and this is what allows my WFO to get to temperature as quick as it does. I did not assume in my design that the steel shell was a significant portion of the heat reservoir in my WFO although undoubtedly it does help.

    Hope this helps,
    Wiley

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