MBE (Mini Black Egg) Project

[Jackie Tran]

OK you pizza making fools.  You got me hooked and now I'm working on my own version of the LBE.  It will be a MBE (mini black egg) using the smokey joe weber (14").  I will be using firebricks for the hearth.  I plan to make the bottom stone with firebricks to be about 13" in diameter.  Not sure if that will allow sufficient room for air circulation.  I may even do 12.5" if that doesn't work. 

I plan on only making 12" pies or smaller in this thing.  The lid of the smokey joe is also pretty low already so I'm not sure if I'll have to lower the ceiling at all.  If I do, I plan on using sheet metal.  Anyone see any issues with sheet metal?

I also plan on sitting this thing on 160K btu burner.  I know this is too much heat for it but plan on testing it at only half throttle to start with.  I'm wanting a 160k btu burner instead of a 60K btu burner b/c I plan on using it for outdoor frying and wokking as well. 

My only concern is that I may have to cut a hole 11" at the bottom of the grill to fit onto the burner so I hope that's not too big of a hole. 

I'm also planning on using a pan filled with lava rocks or sand as a heat difuser.  I'm not sure I even need the heat difuser.  What are the experts opinions on this? Is it necessary or not?

I'm in the process of gathering the materials and should have some pics up soon.

This little project will set me back $160 or so.  Just for a few home made pizzas?  Have I lost my mind? 

[Jackie Tran]

So I went out and bought all the stuff yesterday.  I searched Craigslist but the 14.5" weber is hard to come by.  Lots of 18 and 22" but not 14".  Being that they are quite inexpensive at $30 new, I opted for that.

The only high output propane burner I could find locally was the Brinkman all-in-one smoker/grill/fryer. I didn't want to pay $120 for it but what choice did I have?  I needed to make one of these now! 

Since I also don't have a gas grill anymore, I had to repurchase a tank of the LP at $48 at lowes!    didn't know the prices had gone up on those.  After all that was said and done, I was over $200 on this project.  Not bad if I can actually make good pizza with it. 

First thing was to unpack everything and gather my tools.  I needed some masking tape, marker, measuring tape, rotozip tool, and hand saw with a metal cutting blade.

Measured out the base of the burner and it was at 7.5" so I decided to cut out an 8" hole from the weber.

[Jackie Tran]

Next I had to decide how to go about measuring out 8" in diameter and how to mark off the weber.  So after some thought, I decided to get a bamboo skewer and cut it at 8".  Placed a mark in the center of it at 4" and lined it up by sight against the screw in the bottom of the weber and marked it off on each side. 

Now how to go about cutting this thing.  I decided to save some time and use the rotozip and boy am I glad I did that.  Even with the rotozip tool, it took about 20min to cut.  I couldn't make one cut but had to make mutliple cuts as i went around.  Didn't look pretty but got the job done. 

[Jackie Tran]

I went ahead and set her up since I had pizza dough waiting to be bake on the MBE.  Fired here up and played around with the propane adjusting valve and air intake valve to get a moderately high output. 

Here's what she looks like set up. 

Notice that the burner sits down in the stand and there's a bout a 2" gap between the weber and burner.
I monitor temps every 15m or so and after an hour of preheating, did not achieve the temps I wanted which was 800-900f.  Instead I got around 700 and it was only in a few spots. 

Lots of potential culprits.  Could have been that gap at the bottom.  Could have been the lava rock heat diffuser.  It also could have been the thick firebricks I used with a thin pampered chef stone.  The stone was almost as big as the grill and only left a 1/2" gap.  I had no other stones at the moment so had no other choice but to use it. 

[Jackie Tran]

I decided to cook the pies in the home oven since I wasn't able to get the desired temps.   After some sleep and dreaming about more pizza, I decided to make some more modifications to the grill.

I cut some slits around the bottom hole so that the grill could sit into the burner grate.  This will get the grill closer to the heat source and close that 2" gap. 

I'll go out this afternoon and see if I can find a decent pizza stone that is 12" in diameter.  This should allow for sufficient air flow around the stone. 

[Matthew]

Tran,
I've got to give you props bro; you're one determined dude!   FWIW, before I built my WFO I was going to buy one of these.
http://www.brinkmann.net/Shop/Detail.aspx?category=Outdoor+Cooking&subcategory=Gas+Grills&sku=810-5000-0&series=OUT-1001-0&seriesname=All-In-One&id=910
I still think that it would work really good & all you would have to do in mount a top stone onto the lid & cut a loading opening in the front.  It comes with a hp burner & the grate has a 50lb capacity so you don't have to worry about any sagging.

Matt

[Jackie Tran]

Thx Matt, the quality of pies you guys are putting out gives me the motivation.    That Brinkman is the exact set up I got.  I didn't need all the other stuff that came with it, but it was the only high output burner I could get locallly.

I went out to look for a stone yesterday so I can start baking pies with it.  The only 12" stone I could find was a Kenmore ceramic stone made in China from Sears.  It has a high chance of cracking but may do while I wait for a real stone to come in the mail.  I'll put a pan with a layer of sand or fine rocks under it to disperse to heat to hopefully prevent crackage. 

Take a look at what else I picked up while I was at the cooking store. 

[Jackie Tran]

So here's how the MBE is currently sitting.  After a test bake I should be able to make adjustments if needed.

No more gap at the bottom.  There is a 1" gap between the stone and the side walls.  I plan making 12" pies so that the rim of the crust sits to the edge of the stone all around.

The ceiling height is also rather low.  At the highest point, it is about 3" and less as you approach the sides of the lid.  This should be right, but if I need to I can elevate the bottom stone.   
If I can avoid putting a stone in the lid, I would rather not.   The problem with the MBE, is that it's small.  If I mount a top stone it would obstruct the top vent openings.  I'm not sure if closing off the vents helps or hurts the baking process.  From Villa Roma's post, it seems that the vents aid in airflow and increasing temps.   I'll know more after a few tests, but for now his word will do. 

[Jackie Tran]

Here's the other reason I wanted to build the MBE.  I could use the burner for (stir)frying things outdoors.  I love bacon but the wife doesn't like it smelling up the house.   I occassionally make things in the wok as well and prefer to do stir frying out doors.

As it is, the wok can sit right on the lip of the weber.  It floats about 1/4" above the grate, so I don't have to remove the weber to use the wok.  Actually by removing the gap and having the weber in place, it acts like a wind break anyways.

[Jackie Tran]

Having had a problem getting it up to temps the first time around, I took out the lava rocks and used just the new pizza stone i got from sears.  I did have a metal pan underneath the stone with a layer of pebble stones to disperse the heat. 

Cranked up the temp and within 20 min had a surface temp of 900.  I took the heat back down to 800 but still scorched 2 pies very quickly.  Dough was still raw in the middle. Sorry no pics of the burned pies.

I then decided to revisit the orginal LBE thread for ideas and lo and behold, Villa Roma has already built an MBE.  I guess I must've missed it the first read through.  Picked up some great ideas from Villa Roma and decide to make more mods to the LBE.

I decided to put the firebrick back in so I had cut it down to size.   I also lined the inside with heavy duty aluminum foil.    Following VR's lead, I cut a vent in the lid 1x6"  to encourage airflow from back to front.  I hope this solves the issue of lack of crust browning. 

Cuts again were made using the rotozip.  I seriously have no idea how VR is able to make those smooth cuts using just a hand saw.   I tried using a keyhole saw with a metal cutting blade and made very little progress, so I went back to the rotozip.

[Jackie Tran]

A few more pics of the new top vent.

With the hearth and lid in place, there is 2 1/4" of ceiling height at the tallest point and gradually decrease as you move towards the rim.   If I can't get sufficient browning on top, I may put in an 8" stone on top down the road.

I hope these are all the mods that are required though. 

[Jackie Tran]

I've now tried 2 bakes on this thing and I'm still burning pies.  Too much heat to the bottom and not enough on top.  Tomorrow I'll make another mod that will hopefully fix that.  I plan on suspending a pie or cake pan filled with ceramic briquets to buffer the heat to the floor and direct it more to the edge. 

Having tire of burnt pies, I decided to go a completely new direction with the MBE tonight.  Chicken fajitas....  

So far, this thing is working better as a grill than a pizza oven.  Oh well, back to the drawing board. 

[Tampa]

Tranman,

Great posts.  Pls let us know how it works out.

I'm especially interested in your initial result that 700F was a hard target to meet.  When I read that and saw the pictures, I figured you were limited by the lack of venting out the top and that problem would be corrected when you cut the side slit.  But I think you said the temp increase was due to removing the diffuser stones - in either case, it seems the flame was not getting to the stone, or you would have seen a big temperature jump.  If you choke the airflow, because of stones, or because of narrow gap between the pizza stone and sidewall, or because of the outlet, etc.,  the hot air will get backed up and tend to flow out the bottom.

If you are able to get the airflow correct, around the stone, into the lid, and out the slit, I think you will be able to get by without adding a top stone.  The "just-right" amount of hot air is key to having the top and bottom of the pie done at the same time.  Two "throttles" come to mind: the amount top lid vent is open/closed, and possibly adding foil under the pizza stone.  As I'm writing this I remember that you switched from a highly-conductive pizza stone and went to a less-conductive firebrick, so the foil may not be necessary.

Real world test results often differ from my semi-educated predictions.  I'd encourage you to share your findings so others may benefit.

Dave

[Ronzo]

Tranman, keep up the tinkering. You're inspiring!

[Jackie Tran]

Thanks for the kind words guys.  Tampa, I really appreciate your input. 

I'm especially interested in your initial result that 700F was a hard target to meet.  When I read that and saw the pictures, I figured you were limited by the lack of venting out the top and that problem would be corrected when you cut the side slit.  But I think you said the temp increase was due to removing the diffuser stones - in either case, it seems the flame was not getting to the stone, or you would have seen a big temperature jump.  If you choke the airflow, because of stones, or because of narrow gap between the pizza stone and sidewall, or because of the outlet, etc.,  the hot air will get backed up and tend to flow out the bottom.

Yes you are right.  My initial issue of getting temps above 700 had to do with 2 factors.  Using the lava rocks at the bottom as a diffuser barrier and setting a 13" pizza stone on top of firebricks.  The 13" stone left on a 1/2 gap around the perimeter.  That along with the unmodified vent lead to the lower temps.

I have since remedied both factors.  I have increase the perimeter gap to 1" and have modified the lid vent.

After having burnt a few pizzas on the mbe, I'm convinced that 650-700F temps is where I want to stay for now.  Any hotter and the bottom burns too quickly.  Even if I can equalize the  temps from above and below or in a perfect world get higher dome temps, I still have to rotate the pizza since the edge near the vent won't brown.  That means the pie has to sit in the oven longer.  OK by me since I like a crispy bottom and rim anyways.
 
On my 2nd bake, I removed the lava rocks and used a smaller 12" stone.  I place the stone on a 12" metal disk and had a layer of tiny pebbles underneath to disperse the heat so as the think cheap stone would crack.  This is when I got 900F temps in 20 min.  Way too hot!

So now I have my firebrick hearth cut and in place and a new lid vent, but the hearth is still too hot compare the to the air circulating above the pie.  To remedy this, I went ahead and added an 8" disk to the the dome to lower the ceiling.  I hope this helps concentrate the flow of hot air a bit better rather than trapping some of it in the dome.  The dome of the smokey joe is pretty shallow to begin with. 

Next step is to add back the lava rocks or add a diffuser layer.  But where to add that layer?  Down low at the bottom grate with lava rocks or just below the hearth by hanging a ceramic plate?  Well Villa Roma added hung a ceramic plate just below the hearth and I can just about see his reasoning. 

Reply #703 http://www.pizzamaking.com/forum/index.php/topic,4753.700.html

The potential issue with having the diffuser plate (with lava rocks) down below, is that the heat can encompass the lava rocks and then rise straight up into the middle of the hearth.  The potential advantage of hanging a diffuser layer below the hearth is that it will absorb most of the heat and hopefully distribute it to the perimeter.   I'm not sure that this is how it will work out but that' how I imagine it anyway.

Anyways, I don't have a 8-10 ceramic plate so tomorrow I'll go to the thrift store and look for a cheap pan.   I plan to take the handle off and fill it with either ceramic briquets or pebble rocks.  Anyways I'll keep you guys posted on my progress.   

[Jackie Tran]

So last night before grilling up the chicken, I fired up the MBE for a quick temp test.  I was still getting too hot of temps so I decided to abandon the test and grill up some chicken instead.  I prep'd the chicken while the lid was off and the bricks were cooling. 

About 20 minutes later, I placed a couple of the warm hearth bricks on my wife's glass table outside without even thinking twice about.  After dinner, I started cleaning up and saw that the bricks had cracked the glass table.  The crack was about 2" in length. 

About 2 hours later, I hard a LOUD crash coming from the front patio.  I turned the lights on and saw this......

[Jackie Tran]

That glass is pretty thick at about 1/2" thick.  Needless to say my wife isn't very happy about it.  That table has survived 3 moves.  She did a quick search and looks like that screw up is gonna set me back about 250 bones.   OUCH!!  As if pizza making in itself wasn't expensive enough already.

So she's kicking me outta of the house for awhile.  Anyone looking for a part time amateur pizza maker?   

[Ronzo]

That glass is pretty thick at about 1/2" thick.  Needless to say my wife isn't very happy about it.  That table has survived 3 moves.  She did a quick search and looks like that screw up is gonna set me back about 250 bones.   OUCH!!  As if pizza making in itself wasn't expensive enough already.

So she's kicking me outta of the house for awhile.  Anyone looking for a part time amateur pizza maker?   

you're lucky you're still alive...

My wife would have shot me.

[scott123]

I probably would have sprinkled a few acorns around the table and blamed it on squirrels 

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

[brayshaw]

Tranman that sucks! Hope your wife forgives you soon! 

You mentioned how much this pizza thing costs....Look at my car I just sold to fund my business start up. I am now driving about in a beaten up/paint faded/dented 15year old ford fiesta diesel!