Author Topic: MBE (Mini Black Egg) Project  (Read 57511 times)

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Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #40 on: June 16, 2010, 04:22:27 PM »
I just priced a new 10.25" CI skillet at $20. I just feel weird about taking a hack saw to the handle of a new skillet and subjecting it to hi temps.  Almost seems wrong in a way. :'(

Scott I may give the sandpaper a try and see how I feel. I like that idea better than torching it off.  If it works well, I'll still look for a CI skillet at yard sales and what not.


Offline Ronzo

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Re: MBE (Mini Black Egg) Project
« Reply #41 on: June 16, 2010, 04:56:25 PM »
I just priced a new 10.25" CI skillet at $20. I just feel weird about taking a hack saw to the handle of a new skillet and subjecting it to hi temps.  Almost seems wrong in a way. :'(
I couldn't do it. I'd cry trying.

I'd go the "rusty old no longer useful for cooking" route.
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Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #42 on: June 16, 2010, 05:07:56 PM »
Ron I have pies to bake tonight!  ;)BUT I don't want them to be my last pies either.  :o

I'll swing by a goodwill on the way home from work and see what they have. 

Offline Ronzo

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Re: MBE (Mini Black Egg) Project
« Reply #43 on: June 16, 2010, 05:19:37 PM »
Maybe even a rusty old cast iron comal (round tortilla griddle) instead of a pan.
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Offline Tampa

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Re: MBE (Mini Black Egg) Project
« Reply #44 on: June 16, 2010, 05:22:07 PM »
I do have a little feedback on the design.

Part of the overall approach, IMO, should be managing the hot airflow through the Egg.  With that high BTU burner below acting like a jet engine, the flow has to go somewhere.  If the slot cutout isn't large enough, along with the top vent (now plugged) then the jetstream has to go somewhere, probably back out the bottom (wasted).  Hot air compresses a little bit, but when you have a constant flow like a jet, it will generally vent wherever is the easiest.  Ideally, you want that flow to impinge on the underside of the pizza stone, then U turn, pass over the top of the pie and and exit the slot.

You have so much heat there, that once things warm up and reach steady state, there should be little temperature drop in the flow and the top of the pie would cook as fast as the bottom.

With that in mind, the upper plate mostly serves to keep the hot air flow over the pie.  It doesn't matter much the thermal mass, just that the flow is right.

To me the underside pan and stones are a bit of a mystery.  The hot air is forced around the pan then expected to turn around and heat the stones again?  Before I got to crazy with airflow, I'd just try some HD foil under the cooking stone (no pans, no stones).  If the EggHeads have experience with pan and stones, then I would defer to their real-world experience.

Dave


Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #45 on: June 16, 2010, 09:34:48 PM »
Dave, thank you for your feedback.  It's great to have your feedback as the science of these things tend to escape me sometimes. 

I have tried just to heat the MBE with the hearth stones alone and no diffuser pan and the hearth gets too hot.  The idea is to get the air above hotter than the stone.  To get the air super hot, I have to run the burner at a high rate which results in too high of temps for the hearth.  ideally I would like to start out with a hearth temp of 700F but want the air above around 800F?

Your idea of putting a HD foil under the stones may not work b/c with direct heat on the HD foil, the foil just about evaporates.  Only after 2 firings, the foil on the side walls of the egg are breaking up and the heat may not be as direct  in those spots.   What I have found lately is an 11" aluminum disk that I will triple wrap with HD foil and place under the hearth stones directly.  It may be enough of a heat diffuser to work (without the addition of a thicker diffuser pan underneath).

If this experiment fails,  I can always go back and add the diffuser pan.  The pan maybe a needed addition for the bigger eggs and not for the mini.  I measured the height from the burner to the top grate (bottom of the hearth) and it's just shy of 7".  Anyways I'll do a test bake late tonight and have the results up by tomorrow. 

I did stop by Goodwill on the way home and was able to find a 10" SS pan for $4.  I should be able to cut the handle off with my rotozip if I need the pan difusser after all. 

Offline Tampa

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Re: MBE (Mini Black Egg) Project
« Reply #46 on: June 17, 2010, 08:29:29 AM »
I may be more science-trained than some on this forum, but real-world results trump science in my mind, especially when it comes to thermodynamics and heat transfer.  I have not kept up with the latest EggHead results, and should, but I suggest you keep a closer eye on their progress over my ďscienceĒ.

In some ways, itís great that the HD foil is melting.  The places of melt will tell you where the hot spots are, and give some insight into airflow.  Iíd get one of those thin steel cookie sheets, or some extremely thin sheet steel, and put that under the stone.  The melting point of steel is entirely different from aluminum, and although the steel might rust over time, it will serve as a test.  If you are gamey, pick up one of those craigs-list discarded stainless grills, and cut off a section of stainless using tin snips.  There are differences in stainless (303 vs. 304, etc.) but ignoring that, stainless should be a reliable barrier and comparable in purpose to HD foil.

What Iím suggesting is a static/non-moving air gap between the impinging flame an the stone.  Air, even hot, is a great insulator.  The small holes in the stone are enough as long as the stone isnít directly in the flame.

The stainless steel pan you bought is great, but Iím still a fan of first putting a thin metal sheet directly under the stone, and if that doesnít work, later try the bucket for lava rocks.  I see the bucket approach as adding a lot of potentially unnecessary thermal mass to the system causing longer warm-up times and possibly unproductive airflow.  If one layer of steel didnít keep the stone temp low enough, Iíd try two layers of steel, separated by either metal lath or sand pebbles Ė something to add a little air-gap insulation.

Most important, do what works for you.  Feel free to ignore these suggestions.  The quest is tasty pizza, after all.

Dave

Offline Ronzo

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Re: MBE (Mini Black Egg) Project
« Reply #47 on: June 17, 2010, 10:45:44 AM »
Tampa, that sounds like good advice to me.
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Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #48 on: June 17, 2010, 11:09:46 AM »
I probably would have sprinkled a few acorns around the table and blamed it on squirrels  ;D

Seriously, though, that's a bummer.  I don't think there's anything more thermally fragile than glass.

Not sure how I missed this earlier, but that's pretty funny Scott.  :-D

Well I took the MBE out for spin last night and the force was not with me.  I had 2 disasters, one of which was totally avoidable so I'll post about so that others might avoid my folly. 

First attempt was the metal aluminum disk tripled wrapped in HD foil under the stone.  For some odd reason I didn't see this one coming.  15 min after firing the MBE up, I notice a pool of silvery liquid under my burner.  Hmmm, I wonder what that could be?   Turned the burner off, unloaded everything and this is what I found. 

Yupp, the friggin disk got smoked!  Some of the aluminum had dripped into the burner head.  I tried to fire it up to hopefully soften it up to remove but to no avail.  With the aluminum plug in place, 90% of the burner holes still work.  I decided it wasn't a big deal as I can just turn that not burning side towards the front where the vent is. 


Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #49 on: June 17, 2010, 11:19:29 AM »
Ok so I decided to go with plan B.  Took the hot stones off carefully and placed them on a rack on the ground avoiding the remaining glass table top.  See I'm a fast learner!

I decided to give the steel pan a shot.  Out came the rotozip and lobbed off the handle in just a minute or 2.  Loaded the small round firebrick, steel pan, and a few ceramic briquets into the perimeter of the pan.
Fired it back up and started  taking note of the temps. 

The pan is 10 1/4" and the hearth is 12".  The pan sits directly under the hearth.  I figured with would help direct the heat more to the perimeter of the hearth rather than the middle itself. 

Checked temps at 10 min and 20 min.  At 20 min, got an average reading of about 650F.  Perfect.  Nice low temp to start with for a trial bake.  Stretched the dough quickly and loaded within a few mins.  Didn't recheck temps but I know it wasn't above 700.   Loaded the pie and within 30 seconds I notice a slight faint aroma of burnt crust.  I'm well familiar with this scent as I have burnt many pies.

Lifted the lid and the bottom was burnt and the back edge was burnt.  I decided to put the pie back since it wasn't salvageable to play around with browning the rest of the rim.  Here's the pie.



Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #50 on: June 17, 2010, 11:25:21 AM »
The really strange thing is that I was  getting hearth temps of 650.  This was not a mistake.  I took multiple readings at 2 different intervals so I'm confident that's what the hearth was.   Yet when I loaded the pie it burnt within 30 seconds as if the hearth temp was 850F or more. 

The only explanation I could come up with is that the ceramic stones right under the hearth were super hot replenishing the heat that was just given up to the pie.

I will revisit my initial set up of putting back the lava rock barrier at the lower grate for the next try.  That should place a nice large air gap between the lava rocks and the stone hearth to decrease hearth temps.  I will also take Tampa's advice of putting a steel disk under the stone as well. 

I still have hope for this project.
« Last Edit: June 17, 2010, 12:27:37 PM by Tranman »

Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #51 on: June 17, 2010, 11:28:53 AM »
Whoops forgot to say.  Thanks guys for the input and advice so far.  It's much appreciated.   :)

Tampa, great suggestions on making the disk out of a cookie sheet or old SS grill.  I'll look into that. 
Also I did notice the hot spots on the aluminum foil so you are right about that as well. 

I really thought the pan idea would work.  It made sense in my mind anyhow.  I was surprise that it didn't "pan" out.   I agree, it's hard to argue with real world results. 
« Last Edit: June 17, 2010, 11:33:08 AM by Tranman »

Offline Tampa

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Re: MBE (Mini Black Egg) Project
« Reply #52 on: June 17, 2010, 11:57:59 AM »
Yo!  Youíve got some serious underside heat going on Ė a big mismatch between the top and bottom cooking.

Some of that is to be expected because the bottom is conduction and the top is convection.  Itís the difference between cooking touching a hot pan and holding your hand several inches above a gas burner.  Both are ouch, but touching a hot pan is instantaneous.

In reexamining the photos, your stone is only seven inches from the flame.  Dang, that feels close.  Is it possible that the flame jets that high?  The early LBE videos suggest a considerable flame.  If so, you may want to throttle that bugger back, a lot.

I wouldnít worry too much about the aluminum in the burner.  But if you want to get it out, Iíd try turning the burner upside down and taking a propane torch to the aluminum (or better yet, map gas).  That should be hot enough to melt it away.  Leather gloves would be good.

This all suggests to me that you have to get that heat over the top.  (The pie is smoked on the bottom and the top cheese hasnít even started to brown.)  Charring on the rim is somewhat of a good sign.  It tells me that at least the flame is making itís way around the stone and up the sides Ė in some parts.  The backside of the rim, the part away from the camera photo, seems less charred suggesting that the flow was uneven Ė possibly the pizza was off center.

Iím still a fan of one, two, or even three plates under the stone.  The first plate out of stainless steel (or mild steel as a test), then a little sand, then an aluminum plate, then sand, then aluminum foil, then stone.  If it were me, Iíd get everything at home depot.  I think they have a little sheet metal in the roofing or hardware area, and you can buy aluminum flashing cheaply in rolls (thatís what I used on the RPG to cut the hood volume.)  Think of it as the opposite of using layers of clothes in the winter.

I know you are trying to maximize the cooking surface so Iím trying not to think about what appears to be a narrow gap between the stone and sidewall of the grill.  I guess you could take out that one little brick wedge piece in the back-left corner of IMG_4055 and throw a pie.  If that area of the pizza subsequently chars like crazy it would suggest the airflow is choked and it really wants to vent.

Dave

Offline Tampa

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Re: MBE (Mini Black Egg) Project
« Reply #53 on: June 17, 2010, 12:11:51 PM »
One other comment.  Notice how the aluminum disk is melted Ė one side burned away and the other side almost untouched.  That tells you where the heat flow is.

Iím guessing that the burn area is directly under the slot you cut in the lid.  If so, Iíd move all the stone over to the slot right against the side of the grill.  That will leave a bigger gap on the back side so the flow is up, around the back and sides, over the pie, then out the front.

Getting even more bold, I would consider cutting another (extra/replacement) brick to exactly match the weber grill radius, skooch it right up to the side of the cutout slot so you block off the jetstream sneaking the front.  Then just place the pie a little forward when you drop it.

Warning: in the early days of my oven experiments I was almost always wrong.  Now that I have more experience, Iím Ĺ smart, so you never know.  (And I really like this last suggestion.)

Dave

Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #54 on: June 17, 2010, 12:14:16 PM »
Thanks for the feedback Dave.  I have been considering several of the points you made.  One of which is to shave the periment of the stone down a bit more to improve airflow.   If you notice I moved the stone closer to the front so that the gap is bigger in the back.  I didn't think it was necessary to have the gap upfront in right below the lid vent.  Well that spot burnt the rim so that gives me an idea of how wide I need to make that gap inorder to get some charring of the rim but not burn it.  The next step is to shave down the diameter of the hearth a bit and move the stone back towards the wall a bit.  

Yes, it's a high BTU burner and I need to scale it back.  I guess it's just like pizza making.  There's so many variables all working at once and all have to work in harmony to get a good pizza/bake.  This process of trouble shooting and optimizing those variables are very normal.  

Thank you for the suggestion on how to get the aluminum out.  It's not big deal that it's there but i do have a mapp torch and will burn it out.  

I think I'm done with putting aluminum under the hearth even if it's sandwiched between sand and SS metal.   I think I will shoot for 1-2 stainless steel disks and see what happens.  

I'm also hoping that bringing back the lava rocks will immensely help with decreasing hearth temps.  I just need to leave a gap b/t the lava rocks and side walls as to not obstruct air flow.  

Thanks again.

Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #55 on: June 17, 2010, 12:24:46 PM »
One other comment.  Notice how the aluminum disk is melted Ė one side burned away and the other side almost untouched.  That tells you where the heat flow is.

Iím guessing that the burn area is directly under the slot you cut in the lid.  If so, Iíd move all the stone over to the slot right against the side of the grill.  That will leave a bigger gap on the back side so the flow is up, around the back and sides, over the pie, then out the front.

Getting even more bold, I would consider cutting another (extra/replacement) brick to exactly match the weber grill radius, skooch it right up to the side of the cutout slot so you block off the jetstream sneaking the front.  Then just place the pie a little forward when you drop it.

Warning: in the early days of my oven experiments I was almost always wrong.  Now that I have more experience, Iím Ĺ smart, so you never know.  (And I really like this last suggestion.)

Dave



I didn't have the where with all to pay attention to exactly where the disk was place.  The melted portion obviously dripped into the head.  I believe it is the back side of the burner where the gap is biggest and where the foil has dissintegrated most.

I wasn't clear before, but pushing the stone forward towards the front air gap is what I did do and that gave almost abit too much heat to the back side causing the charring on the rim.  Again, my next step is to shave the hearth stone down a bit and adjust the stone back towards the wall a bit to optimize the heat flow. 

I like the idea of having a firebrick lip right under the vent to block hot air from exiting there.  This has been done already but it does sound like a good idea, so I will see about implementing that if these next few mods don't actually work like we think they will. 

The mod you are talking about is similar to one PizzaCraver did in reply #753

http://www.pizzamaking.com/forum/index.php/topic,4753.740.html

Offline Tampa

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Re: MBE (Mini Black Egg) Project
« Reply #56 on: June 17, 2010, 12:40:18 PM »
I love that pizzacraver innovation.  Thanks for sharing.  Later today or tomorrow I'll get back on that LBE thread and figure out what I've been missing.  These guys are really evolved and have a lot of good ideas.  For me, I need another appliance on the back deck about as much as a fitness coach would say that I should eat another slice of pizza.

I'm a big fan of the rotisserie as it helps even out the cooking.  Pizzacraver apparently went with a lazy suzan (my first solution on the rotisserie pizza grill).  I'm dying to see if anyone hooked up a rotisserie in a LBE, as I did in the grill.  You can buy a spare rotisserie from Walmart for $20 or so.

Got to run.

Dave


Offline Jackie Tran

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Re: MBE (Mini Black Egg) Project
« Reply #57 on: June 17, 2010, 12:46:06 PM »
Tampa, I had very briefly given that thought some consideration, but with my setup I don't think there is room. ;D

Offline scott123

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Re: MBE (Mini Black Egg) Project
« Reply #58 on: June 17, 2010, 06:30:15 PM »
Tran, that was overfermented dough. Not hugely overfermented, but still past it's prime.

There's prevailing theories here, and elsewhere, that as dough overferments, the yeast consume more and more sugar, resulting in a dough with very low residual sugar.  I feel differently.  I've talked to experts about this, and, the theory I resonate the most with is that yeast, in a bread environment, don't eat that much sugar (as opposed to a beer environment where they feast).  The lack of yeast activity as a dough overferments isn't the result of lack of nutrients, but a result of an alcohol rich (and possibly acid rich) inhospitable environment.

The bottom line is that overfermented doughs burn a lot faster than those with less fermentation.  I'm 99% certain that it's sugar that's to blame.


As far as getting the egg to work right, unless you hang a stone ceiling, I don't think there's much hope for getting close to a decent hearth/ceiling heat ratio. Even then, I think it's hard to do.

Next time, close the top vent (if it isn't already closed) and make sure the gap around the firebricks is equal on all sides. How much gap is there between the s/s pan and the walls?  It needs to be a little bit wider than the gap you have for the firebrick. Assuming the gap is wide enough, go with the s/s pan under the hearth (with more ceramic briquettes) and time the pie so that it goes in with a hearth temp of 500 (or omit the pan entirely and go with a 500 deg. hearth temp bake). It may seem low, but with intense heat coming up from the bottom burner (even with the pan in the way), the hearth will jump in temp as the pizza bakes. This will give you a good idea how much heat you can collect in the headspace to bake the top of the pie. I don't think that burner, in that scenario, will pump out enough heat to give you something truly Neapolitan-ish, but it should give you enough umph for a 3-5 minute pie.

You're basically baking your pizza during the time it takes for the blazing heat on the bottom of the stone to travel to the top.

You can launch  the pizza through the slot, right? In this scenario, you want to keep the lid on. That collected heat is the difference between a pale top and a done top.

The one downside to this is that, by the time the pizza is cooked, the stone will be considerably hotter, so if you want to do another pie, you'll have to turn off the burner and wait for the stone to cool- most likely for at least 15-20 minutes. With a second pie, since the stone should be more equally heated, you might want to bump up the starting temp to 550, but not much higher.

You might be able to recreate this effect a little easier by using two layers of firebrick.  This will cause the heat to travel a little slower AND it will move the pie closer to the ceiling- both good things. By the way, with the lid on, you've got at least 3/8" clearance on all sides of the existing firebrick, right?  It looks like the the firebrick has enough clearance on the grill, but the lid slopes inward, so it's possible that there may not be enough clearance on the sides of the lid. 1/2" clearance is ideal, but, since you're dealing with a small space, I think you can trim it to 3/8", but I wouldn't go less.  Should you add another layer of brick, you'll definitely want to size it accordingly for the sloping lid. If an extra layer of brick pushes you too close to the ceiling, then I might try a cheap round pizza stone on top of the brick. That kind of stone is notorious for lack of resistance to thermal shock, but, with the firebrick between you and the burner, I think you might be alright.  Just make sure you've got the gap.  Air flow from the burner to the top of the lid is critical.
« Last Edit: June 17, 2010, 06:45:30 PM by scott123 »

Offline Pete-zza

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Re: MBE (Mini Black Egg) Project
« Reply #59 on: June 17, 2010, 07:59:22 PM »
There's prevailing theories here, and elsewhere, that as dough overferments, the yeast consume more and more sugar, resulting in a dough with very low residual sugar.  I feel differently.  I've talked to experts about this, and, the theory I resonate the most with is that yeast, in a bread environment, don't eat that much sugar (as opposed to a beer environment where they feast).  The lack of yeast activity as a dough overferments isn't the result of lack of nutrients, but a result of an alcohol rich (and possibly acid rich) inhospitable environment.

The bottom line is that overfermented doughs burn a lot faster than those with less fermentation.  I'm 99% certain that it's sugar that's to blame.


scott123,

I am not sure what Tran used as a dough formulation, but I think you may have put your finger on the problem, or at least one of them. In my experience, and where low residual levels are more likely, is when the dough contains a lot of yeast. I remember that Marco (pizzanapoletana) once posted that you would need around 5% commercial yeast in order to run out of sugar, although he may have been thinking of unmalted flours such as the Caputo flours. It took me a while to find his post but it is at http://www.pizzamaking.com/forum/index.php/topic,1055.msg9357/topicseen.html#msg9357 (item 3). I also know from personal experience that if a small amount of yeast is used and the fermentation process is slowed down to a crawl, it is possible to have the dough last over 15 days of cold fermentation (I went as long as 23 days) and still get good crust coloration because of the sufficiently high residual sugar levels.

Professor Calvel also discussed the relationship between pH, residual sugar and oven spring. I quoted the pertinent portion from his book The Taste of Bread at Reply 136 at http://www.pizzamaking.com/forum/index.php/topic,5851.msg86732/topicseen.html#msg86732.

Having worked with room temperature fermented doughs, I know how easy it is for a dough to overferment, even with minuscule amounts of yeast and especially in the summer.

Peter


 

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