Author Topic: 41" low dome WFO build  (Read 20807 times)

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Offline Jackie Tran

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Re: 41" low dome WFO build
« Reply #25 on: April 06, 2011, 09:44:49 PM »
Cool video Gene.  That looks like a lot of fun.  My oven is being put together tomorrow.  ;)


Offline scott r

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Re: 41" low dome WFO build
« Reply #26 on: April 07, 2011, 11:11:54 AM »
WOW!

Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #27 on: April 08, 2011, 11:11:35 AM »
I decided late in the day yesterday to do a test cook on the wfo.  I picked up a 30 lb. bag of Grade A1 Mexican Mesquite lump charcoal.  I dumped 10 lb of it in the oven along with 3 arm sized logs.  After 2.5 hours and 3 more logs, I still needed more heat.  The oven floor was about 200* to cold.

I made an emergency dough and used the cake yeast i picked up at RD.  It wasn't anything special for sure.  Polly O fior di latte and some doctored crushed tomatos that included Pace Picante sauce were used.

I would grade the pizza at 60% by forum standards, probably 96% by the general public standard.  The oven being on the trailer at shin level and underfired were the biggest obstaces to getting better results last night.  None the less, my first wfo pizza.
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Offline Jackie Tran

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Re: 41" low dome WFO build
« Reply #28 on: April 08, 2011, 11:45:32 AM »
Gene 2 things.  The pizza and crust looks good.  I don't know yet, but I keep getting the feeling that my favorite wfo pizza will be in the 3-4min range.  So I'll need lower temps like where you were just at. 

2nd - you are one of the few to use lump coal for a fire and posted about it.  I've only seen one other person mention lump coal.  So I'm curious to know.  It sounds like you used about 15lbs or roughly half of that bag for a 3 hour burn.  What was your final hearth and dome temps and how long was that pie baked for? 

Thanks,
Chau

Offline TXCraig1

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Re: 41" low dome WFO build
« Reply #29 on: April 08, 2011, 11:55:09 AM »
Congrats on WFO pie #1!

You must be loosing a ton of heat our the top. That was my biggest problem with the BBQ mod. It took 10 layers of pyroblankets to hold enough heat in. I would not reccomend them for your WFO. It would be way too hot for the material directly above the flame.

How about welding a 6-8" (or whatever makes sense) rim around the steel oven top and weld up a snug-fitting cover. Then you could fill the top with loose vermiculite?

CL
"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."
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Offline TXCraig1

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Re: 41" low dome WFO build
« Reply #30 on: April 08, 2011, 11:57:13 AM »
I don't know yet, but I keep getting the feeling that my favorite wfo pizza will be in the 3-4min range.  So I'll need lower temps like where you were just at. 

Chau,

What makes you think that? The best pies I've ever eaten were all in the 1.5-2 min range. When baking pies in my grill, the closer to 2 min I can get, the better they seem to be.

CL
"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."
Craig's Neapolitan Garage

Offline Jackie Tran

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Re: 41" low dome WFO build
« Reply #31 on: April 08, 2011, 12:09:27 PM »
Gene would a 2-3" layer of sand over the dome help hold the heat in?

Craig, it's just a gut feeling I have.  I'll have to do a lot of testing to know for sure.   I'm looking for a certain hydration in the dough to get the open moist crumb but I also know it takes a bit more time than 90 seconds to bake off the moisture.  Perhaps I'll settle on a 2.3-3m bake,  or perhaps my new favorite will be a 90 second bake.  Just not sure yet....

Chau

Offline shuboyje

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Re: 41" low dome WFO build
« Reply #32 on: April 08, 2011, 12:57:34 PM »
If you decided you want to add some thermal mass to the dome, I would personally try fireclay.  I'd mix up a dry "mud" with some water and put a couple inches over top of the dome then fire it to drive off the moisture.  I would bet it would have very similar thermal properties to firebrick or castable.

As for fire the oven with lump charcoal, I would throw that idea out.  Lump charcoal is wood that has had it's volatile gases removed via pyrolysis.  Those gases hold btu's so you are already at a disadvantage over wood, and in a WFO it's an even bigger issue.  A WFO needs open flame licking the dome, and those open flames come from pyrolysis of the volatile gases in the wood...the same gases that are gone in charcoal.

Chau,

I don't post much, but read a lot and am pretty sure I have a good idea what you are after.  I would highly recommend firing the oven to 900+ on the hearth.  Once you get the initial spring from the high heat and the crust begins to set a bit I would then move the pie to the cooler area of the oven right in front of the door to drive off the moisture and crisp it up a hair.  There is something magical that happens with a high hydration dough and a 900+ hearth IMHO.  With this method you can get the best of both worlds, I would certainly give it a shot, it is my go to method for a more american style pie.
-Jeff

Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #33 on: April 08, 2011, 02:49:31 PM »
Chau, I would say that the hearth was around 750 and the bake time was just over 3 min.  I used about 10# of lump and no more than 5 arm sized logs.

Craig, I think your idea has merit even if it does have enough insulation.  With the roof on the way it looks now is very Beverly Hillbilly-ish.  A solid roof would clean up the looks alot.  Just above the dome I have 1 layer of 2" thick ceramic insulation rated for high heat.  Above that is a 6" thick bat of regular houshold fiberglass without the paper backing.  The first burn had a pretty funky smell happening, but none last night.

Shuboyje-  Thanks. I never thought about the lump not being able to produce as much heat as wood.  I have used it for several years, but at much lower temps.  When all was said and done last night, I had almost the same size pile of coals as the first test.  So I'm sitting there scratching my head wondering wth happened.  Now I know.

While experimenting with dough I will put another non-lump fire in it and try it again.
I have decided to put this thing on my bbq trailer.  I will have to add another axle and extend the tongue, but the trailer already has amenities that are nice for food prep.
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parallei

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Re: 41" low dome WFO build
« Reply #34 on: April 08, 2011, 05:57:04 PM »
JD- I'd loose the regular houshold fiberglass.   Not sure what'll happen if it gets wet!

Some R-Values:

Vermiculite, loose fill   2.08
Perlite, loose fill   2.7

Not sure about sand, but I think its R is about 0.6 or something.   Perlite is also much, much lighter than sand......

Can't imagine fire clay having a better R than the loose fills, but I could be wrong...........
 

Offline Jackie Tran

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Re: 41" low dome WFO build
« Reply #35 on: April 08, 2011, 06:41:44 PM »
If you decided you want to add some thermal mass to the dome, I would personally try fireclay.  I'd mix up a dry "mud" with some water and put a couple inches over top of the dome then fire it to drive off the moisture.  I would bet it would have very similar thermal properties to firebrick or castable.

As for fire the oven with lump charcoal, I would throw that idea out.  Lump charcoal is wood that has had it's volatile gases removed via pyrolysis.  Those gases hold btu's so you are already at a disadvantage over wood, and in a WFO it's an even bigger issue.  A WFO needs open flame licking the dome, and those open flames come from pyrolysis of the volatile gases in the wood...the same gases that are gone in charcoal.

Chau,

I don't post much, but read a lot and am pretty sure I have a good idea what you are after.  I would highly recommend firing the oven to 900+ on the hearth.  Once you get the initial spring from the high heat and the crust begins to set a bit I would then move the pie to the cooler area of the oven right in front of the door to drive off the moisture and crisp it up a hair.  There is something magical that happens with a high hydration dough and a 900+ hearth IMHO.  With this method you can get the best of both worlds, I would certainly give it a shot, it is my go to method for a more american style pie.

Shuboyje, I wish you would post more.  Excellent.  Thank you for answering 2 questions I've had on my mind for some time.  I did think about that technique briefly awhile ago but it's impossible to know without a WFO, so I'm glad to know that it does work.   I will definitely try it out.  Thank you.  

Chau
« Last Edit: April 08, 2011, 11:24:41 PM by Jackie Tran »

buceriasdon

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Re: 41" low dome WFO build
« Reply #36 on: April 08, 2011, 06:51:55 PM »
Paul, Gene and others, My concern with a setting clay on top of the steel would be the very different rates of expansion leading to severe cracking, plus the fact clay can't adhere to steel. Gene, if I understand correctly you plan on trailering the oven and that would lead to even more cracking.
Don
 

JD- I'd loose the regular houshold fiberglass.   Not sure what'll happen if it gets wet!

Some R-Values:

Vermiculite, loose fill   2.08
Perlite, loose fill   2.7

Not sure about sand, but I think its R is about 0.6 or something.   Perlite is also much, much lighter than sand......

Can't imagine fire clay having a better R than the loose fills, but I could be wrong...........
 

Offline shuboyje

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Re: 41" low dome WFO build
« Reply #37 on: April 08, 2011, 08:17:45 PM »
In a WFO you basically have two things, Thermal mass and Insulation.  An open space surrounded by thermal mass surrounded by insulation to be exact.  I was recommending the fireclay as thermal mass if the OP decides it is needed, not as insulation which is where R-value comes into play.  I envision the "mud" being placed on top of the metal dome and then some form of metal lath being placed into the top of it to loosely hold it in place.  In this installation if it cracks so be it, mass is mass cracked or not.  It will still store heat the same. 

That said this is all only if the OP decided it is needed, as I see it the jury is still out of metal ceilings with no mass.  I don't think we've seen enough to give up on the concept, although I do have my doubts which I expressed in other threads about metal dome ovens.  As a sheet-metal worker by trade with all the skills and tools to fabricate metal ovens quickly and easily and heaps of scrap metal at my disposal I hope I am wrong and it works great!
-Jeff

buceriasdon

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Re: 41" low dome WFO build
« Reply #38 on: April 08, 2011, 08:38:31 PM »
In my other life I was a member of the Sheet Metal Workers of America, hopefully in another year I can collect some pension if any money is still left.  ??? Yes, if some method can be devised to hold the clay together it would help retain heat.
Don


In a WFO you basically have two things, Thermal mass and Insulation.  An open space surrounded by thermal mass surrounded by insulation to be exact.  I was recommending the fireclay as thermal mass if the OP decides it is needed, not as insulation which is where R-value comes into play.  I envision the "mud" being placed on top of the metal dome and then some form of metal lath being placed into the top of it to loosely hold it in place.  In this installation if it cracks so be it, mass is mass cracked or not.  It will still store heat the same. 

That said this is all only if the OP decided it is needed, as I see it the jury is still out of metal ceilings with no mass.  I don't think we've seen enough to give up on the concept, although I do have my doubts which I expressed in other threads about metal dome ovens.  As a sheet-metal worker by trade with all the skills and tools to fabricate metal ovens quickly and easily and heaps of scrap metal at my disposal I hope I am wrong and it works great!

scott123

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Re: 41" low dome WFO build
« Reply #39 on: April 08, 2011, 11:27:07 PM »
While I think that some extra thermal mass is a good idea, cracked fireclay on a sloped surface is going to slide off.  Welding a lip, as Craig mentioned, would support the fireclay, but... welding stainless is a major pita.

I've actually been contemplating a way of keeping refractory on top of a sloped metal roof for some time now.  Something that just came to me is taking heavy duty steel wire and forming it into a big loop.  When your form the fireclay on top of the roof, make it into sections (like slices of a pizza), forming a flat exterior edge with a groove for the wire.  With all the pieces in place, the wire acts like a harness, preventing the refractory slices from sliding outwards.  The slices also need not be too form fitting to make room for expansion.

You probably wouldn't want to drive with the slices in place, but it should be easy enough to assemble/disassemble. I'm thinking maybe 1" thick refractory wedges or possible some perlcrete that's a little heavier on the 'crete to give it more thermal mass.

Offline TXCraig1

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Re: 41" low dome WFO build
« Reply #40 on: April 08, 2011, 11:39:56 PM »
Some R-Values:

Vermiculite, loose fill   2.08
Perlite, loose fill   2.7

Perlite will pop like popcorn if you heat it up too fast which I think might happen where the fire is directly under the metal roof.

CL
"We make great pizza, with sourdough when we can, commercial yeast when we must, but always great pizza."
Craig's Neapolitan Garage

Offline shuboyje

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Re: 41" low dome WFO build
« Reply #41 on: April 09, 2011, 12:30:21 AM »
Welding stainless is certainly more of a challenge than mild steel, but for the few tack welds you would need to hold the ring in place it would be no big deal.  I've got everything I need to throw together a mini mock up of what I'm thinking, I'll throw it together this weekend and see what happens.  Then I can throw it in my trunk for a few weeks and see how it weathers the bumps of the road. 

As for perlite, any used for insulation purposes should already be expanded, that is where it gets it's insulation value from.  Perlcrete is a great insulation for WFO, but if you are looking for thermal mass I think there are much better ways to get there.
-Jeff


Offline shuboyje

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Re: 41" low dome WFO build
« Reply #42 on: April 09, 2011, 06:41:33 PM »
As I said I would, I built a little mock up today to see how it holds up.  It's a 6 x 6 piece of stainless that I then put 3/4" of fireclay "mud" on top of.  I then pressed a 6 x 6 piece of 1 x 2 wire mesh into the surface and put a bit more clay over top of it.  I then slowly fired on my stove top until dry.  Fissures formed along the mesh, but upon cooling I was pretty impressed with how solid and dense it was, I was tossing it around with no effect.  Here's a picture of it before it went in my trunk.  We'll see what it looks like after a few weeks of my 100 miles a day of driving.
-Jeff

Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #43 on: April 12, 2011, 10:33:48 AM »
Thanks everyone for the ideas.  I try to fire it up again this week and see how it goes.
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Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #44 on: April 16, 2011, 02:46:50 PM »
I refired the oven without using any lump charcoal.  With the floor at 850 and climbing, no part of the exterier of the oven was hot to the touch.  It seems to be insulated sufficiently for now.  I do blame the lump charcoal for the low temps last time.  At least in this particular oven anyway.  50 seconds of the burn.   The results were good. I ate one, the neighbor ate one, and we fixed one for his wife.  My 00 flour is expired.  Must find more.
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Offline Tscarborough

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Re: 41" low dome WFO build
« Reply #45 on: April 16, 2011, 03:19:29 PM »
Tack weld metal lath wadded to 1/2 the finished thickness and then put the clay on and around that.

Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #46 on: April 17, 2011, 09:29:05 AM »
I am not sure that this roof needs any modifications.  But, Tom would this stuff make an acceptable clay?
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Offline Tscarborough

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Re: 41" low dome WFO build
« Reply #47 on: April 17, 2011, 09:43:17 AM »
Sure, that is high temp pipe insulation.  It will not like direct flame, but heat is no problem.

Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #48 on: April 17, 2011, 09:45:32 AM »
Thanks Tom.
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Offline Jet_deck

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Re: 41" low dome WFO build
« Reply #49 on: May 12, 2011, 09:40:41 AM »
I got my GI Metals order in from JConk about a week ago.  I also talked him into sending me 10# of AM Pizzeria flour since my no name 00 flour had expired.   I took them both out for a test drive last night.  Without a live fire the oven was a bit out of balance and I plan to follow Toms suggestion above about coating the exterior of the oven roof with lathe and the high temp rated putty.  So here are wfo pizzas 2, 3 and 4.  Number 2 was anemic looking on the top, but 3 and 4 got some heat.  The IR heat gun showed that the floor was about 875.
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