Author Topic: Concrete recipe for Weber mod?  (Read 24393 times)

0 Members and 1 Guest are viewing this topic.

Offline Bada Bing

  • Registered User
  • Posts: 22
Concrete recipe for Weber mod?
« on: June 28, 2011, 04:02:27 PM »

I haven't seen an actual how-to on creating my own version of the Frankenweber, where you mold a dome to fit on top of the Weber kettle.  My goal is a wood- or coal-fired oven on the Weber platform. 

Forno-Bravo website gives these ratios under "insulating concrete" in their glossary:

"A mix of 6 parts Vermiculite or Perlite:1 part Portland cement to make an insulating product which can be used in the Insulating Hearth and for dome insulation in certain types of enclosure."

Are those parts by weight or volume?  I have coarse vermiculate and also some perlite around--they weigh practically nothing.  I don't want to waste it with unnecessary experimentation. 

Also, I am wondering if the texture of this cement is such that I can coat the inside of a kettle dome and then also have it lie thick enough not to require an inner mold.

Finally, I'm wondering if the weber kettle dome is a little low for this purpose: would it help to create a vertical skirt around the dome before using it as a mold?

Thanks for any tips! 
 



Offline shuboyje

  • Registered User
  • Posts: 1221
  • Location: Detroit
Re: Concrete recipe for Weber mod?
« Reply #1 on: June 28, 2011, 10:43:12 PM »
I'm not really sure where to begin here.  In my mind there are a lot of issues to work through to make this a go.

Insulating concrete like you reference made with portland and vermiculite/perlite is not for direct fire contact.  What you need is a refractory material.  Anything portland based will not work.  Even with commercial refractories you would want a dense castable not an insulating castable IMHO.  Dense castables are stronger and better suited for fire contact.  Problem is for an effective oven you then need insulation on top of that.  This all gets pretty big, pretty complex and pretty heavy to get on a weber grill and by the time you are done you would be better off just building a small cast oven and forgetting about the grill.

If you want to turn a weber grill into a small portable pizza oven the little black egg is the only way to go, and I am a STAUNCH wood fired guy so that says a lot.
-Jeff

Offline mnjesse

  • Registered User
  • Posts: 88
Re: Concrete recipe for Weber mod?
« Reply #2 on: July 05, 2011, 10:15:37 PM »
Here is a concrete recipe: http://www.backyardmetalcasting.com/refractories.html
Don found this website and posted it when I had a similar question. I am going to be trying it out this week when I get some time. I will let you know how it goes.

Offline carbon

  • Registered User
  • Posts: 128
  • Location: Los Angeles
Re: Concrete recipe for Weber mod?
« Reply #3 on: July 06, 2011, 06:17:28 PM »
Perlcrete or vermicrete should not be exposed to direct flames.  These mixtures may work over the kettle lid.  It also should not be exposed in its raw form as they tend to crumble easily.  They are most commonly finished with stucco.

Offline meatboy

  • Registered User
  • Posts: 122
Re: Concrete recipe for Weber mod?
« Reply #4 on: September 08, 2011, 02:55:11 AM »
...here is my attempt. I just couldn't imagine how a higher refractory cement : perlite ratio than 1:2 is possible. All above was so brickle that i wasn't able to use it. Now the parts are maybe too heavy. The ring is 29lb (but not completely dry), and the top also...

Offline shuboyje

  • Registered User
  • Posts: 1221
  • Location: Detroit
Re: Concrete recipe for Weber mod?
« Reply #5 on: September 08, 2011, 09:20:12 PM »
Your casting looks really nice, but I do have a few concerns. 

First the simple one.  How high is your dome?  If you plan to fire from bellow like I assume you do I think it is gonna be way to high.  Top heat is gonna be your biggest issue, as it is with all ovens heated from the bottom, and keeping the dome low as possible is gonna be key.

Finally, what type of cement did you use to tie that all together?  I'm gonna assume Portland, but am hoping it was calcium aluminate or something else refractory.  Lately it seems like lots of people want to copy the frankenweber, and I have no idea why.  The oven is poorly to nearly un documented and what little we do know includes that fact that it has been rebuilt at least once.  The use of perlite and portland cement for the oven dome goes against thousands of years of knowledge and thousands of functional ovens well documented online.  One guy does it with questionable methods and results and suddenly everyone wants to follow suit. 

Outside of that I think I basically voiced my concerns in my post a few up.
-Jeff

Offline meatboy

  • Registered User
  • Posts: 122
Re: Concrete recipe for Weber mod?
« Reply #6 on: September 09, 2011, 03:02:58 AM »
1. i build the "oven" because i don't have the place and the money for a real WFO
2. i used refractory cement + perlite
3. the ring's height is 7.5", + 2" for the dome. I use two pizzastones, one is 2", the other 0.8". So the dome is 6.7" away from the pizza, and because it's a WFO with burning wood next to the pizza it's enough!

Offline Ev

  • Supporting Member
  • *
  • Posts: 1826
  • Age: 58
  • Location: Lancaster Co. Pa.
Re: Concrete recipe for Weber mod?
« Reply #7 on: September 09, 2011, 06:50:08 AM »
I think at this point, all you can do is try it out. If it's too tall, just grind off a half inch or so at a time until you think it's right. I'll be watching your progress as I'm soon going to be helping Norma build one like yours, so please post your results.

Offline shuboyje

  • Registered User
  • Posts: 1221
  • Location: Detroit
Re: Concrete recipe for Weber mod?
« Reply #8 on: September 09, 2011, 09:44:46 AM »
I'm not suggesting building a full on brick oven in the classical sense.  My point is it's proven fact that you want dense material as a hot face surrounded by insulation.  A 2:1 mix of perlite and refractory gives you neither insulation or conductive thermal mass.  It's gonna kinda heat up, kinda conduct heat, and kinda insulate.

On the other point, your kettle is what, 22"?  Casting looks 2" thick so now you have 18".  There is a guy around with a 21" oven and he can only cook 8" pies with a fire in.  Fired from the bottom will give you way more room for bigger pies, but the dome will need to be much lower.

I'm not trying to be a jerk, just trying to help you get to a functional oven.
-Jeff


Offline TXCraig1

  • Registered User
  • Posts: 15459
  • Location: Houston, TX
    • Craig's Neapolitan Garage
Re: Concrete recipe for Weber mod?
« Reply #9 on: September 09, 2011, 10:26:52 AM »
I agree with Steve that you just have to try it out and go from there. Personally, I'm optimistic about his chances for success.

CL
Pizza is not bread. Craig's Neapolitan Garage

Offline shuboyje

  • Registered User
  • Posts: 1221
  • Location: Detroit
Re: Concrete recipe for Weber mod?
« Reply #10 on: September 09, 2011, 12:29:41 PM »
Here is a very similar recent conversation that resulted in a very small oven that works well and the owner is happy with:

http://www.fornobravo.com/forum/f2/perlite-mizzou-castable-16351.html
-Jeff

buceriasdon

  • Guest
Re: Concrete recipe for Weber mod?
« Reply #11 on: September 09, 2011, 05:12:47 PM »
Very nice looking casting! Well done, I hope you documented how you accomplished your work as I know people will want to know more about this oven. The furnaces I have built using this type of material can reach temperatures required for melting bronze with no ill effects and those temps are at least three times the temp you want for pizza baking. Bronze becomes molten at around 1600 degrees F., the graphite crucible becomes red from the heat, I'm sure these furnaces run well over 2200 degrees. Keep us informed as to your progress.
Don

Offline mnjesse

  • Registered User
  • Posts: 88
Re: Concrete recipe for Weber mod?
« Reply #12 on: September 13, 2011, 11:07:22 AM »
Here is a very similar recent conversation that resulted in a very small oven that works well and the owner is happy with:

http://www.fornobravo.com/forum/f2/perlite-mizzou-castable-16351.html

This looks like a very affordable backyard oven. What would something like that cost? It looks like it is much cheaper than a traditional woodfire oven.

Offline shuboyje

  • Registered User
  • Posts: 1221
  • Location: Detroit
Re: Concrete recipe for Weber mod?
« Reply #13 on: September 13, 2011, 12:28:45 PM »
As a rough guess I'd say about $60 in castable, $30 in fire bricks, $20 in perlite, and $10 in Portland cement would get you very close to the oven minus the stand.
-Jeff

Offline mnjesse

  • Registered User
  • Posts: 88
Re: Concrete recipe for Weber mod?
« Reply #14 on: September 13, 2011, 05:02:39 PM »
I live in Fargo ND which has temperature extremes (-40 Fahrenheit in the winter and up to 105 F in the summer). How would an oven like this withstand those types of changes? Would it be prone to cracking? Are other woodfire oven styles better able to handle these types of temperature changes? Thanks

Offline shuboyje

  • Registered User
  • Posts: 1221
  • Location: Detroit
Re: Concrete recipe for Weber mod?
« Reply #15 on: September 13, 2011, 05:23:38 PM »
The great thing about an oven like that is you can build it on a rolling stand and move it inside when it's not in use.  If that's not an option then you need to built a water tight enclosure.  So long as the oven stays dry the elements shouldn't be an issue.
-Jeff

Offline SELES

  • Registered User
  • Posts: 87
  • Location: SF BAY
    • I design stuff.
Re: Concrete recipe for Weber mod?
« Reply #16 on: January 09, 2012, 11:45:48 PM »
How is this oven working out for you? The casting is real nice and I'm wondering if you'll share your method.


Offline akuban

  • Supporting Member
  • *
  • Posts: 163
  • Location: Astoria, Queens, NYC
  • Crusty, saucy, cheesy
    • Margot's Pizza
Re: Concrete recipe for Weber mod?
« Reply #17 on: January 17, 2012, 04:23:00 PM »
Meatboy: That is a beautiful casting. Do you have any pics showing the mold you used? My winter project is to build a FrankenForge in time for spring cooking. Seconding SELES here: How is this working out?
¡Hasta la pizza!

Offline SELES

  • Registered User
  • Posts: 87
  • Location: SF BAY
    • I design stuff.
Re: Concrete recipe for Weber mod?
« Reply #18 on: January 19, 2012, 09:16:38 PM »
Meatboy: That is a beautiful casting. Do you have any pics showing the mold you used? My winter project is to build a FrankenForge in time for spring cooking. Seconding SELES here: How is this working out?

My goal as well akuban.

I've been thinking a lot about how this might have been cast and I'm leaning towards metal flashing and a 2X4. Some of the pictures show what look to be seams in the mold which in turned me on to the idea of flashing. I could be way off though, this casting looks maybe too clean for that. However, flashing seems like it's common, cheap and rigid enough to be a worthy experiment and Don's recipe for homemade refractory is relatively inexpensive. So I think as soon as I can pull away from work long enough to pick this stuff up I'm going to give it a shot.

Btw, I noticed your in Astoria and it got me reminiscing about those sausage sandwiches out in front of Home Depot on Northern, one of those and a snapple is the jam.
« Last Edit: January 19, 2012, 09:18:41 PM by SELES »

Offline akuban

  • Supporting Member
  • *
  • Posts: 163
  • Location: Astoria, Queens, NYC
  • Crusty, saucy, cheesy
    • Margot's Pizza
Re: Concrete recipe for Weber mod?
« Reply #19 on: January 23, 2012, 11:31:16 AM »
Yeah. I had the same idea with metal flashing. I think two concentric rings held together by a combo of bolts-and-wingnuts as spacers.

Yes, I'm in Astoria.* So I'll probably be heading to that Home Depot for some supplies -- if I can't find them readily in my neighborhood.

* I like Rose & Joe's, Rizzo's, and Rosario's Deli for slices.
¡Hasta la pizza!

scott123

  • Guest
Re: Concrete recipe for Weber mod?
« Reply #20 on: January 23, 2012, 11:45:55 AM »
Hank and Adam, I don't think Jeff could spell it out any clearer.  This design, as it stands, is not viable.  You're either talking heat from below, with the top of the pizza never getting properly baked or you're talking heat source on the side, which results in an 8" or smaller pizza.

If you guys want to make 8" pizzas, go for it, but, if you want to save yourself a lot of angst, use your webber and build an LBE. Getting a Neapolitan pizza out of an LBE is no easy task, but it's got a much better track record than this. At least with an LBE, you've got a fighting chance.

Offline akuban

  • Supporting Member
  • *
  • Posts: 163
  • Location: Astoria, Queens, NYC
  • Crusty, saucy, cheesy
    • Margot's Pizza
Re: Concrete recipe for Weber mod?
« Reply #21 on: January 24, 2012, 08:54:14 AM »
Thanks for the advice, Scott. On that note, LBE does seem like the way to go. I have been lured by the pizzaforge's wood fuel, but LBE sounds more viable -- and easier to hack in a weekend's time. As always, you are a font of pizzawisdom. Chars!
¡Hasta la pizza!

Offline toddster63

  • Registered User
  • Posts: 233
  • Location: SF Bay Area, CA
Re: Concrete recipe for Weber mod?
« Reply #22 on: May 08, 2012, 11:23:39 PM »
I had wished meatboy success, and hoped he would post some of his efforts, but he and his "FrankenWeber" have seemed to vanish...

His idea is very doo-able. We have the Pizzahacker here in the 'Frisco bay area; the Hacker cooks 10" or so Neopolitan pizzas in his 22.5" Frankenweber, with the perlite-cement sides and dome. He has great reviews on Yelp, and a following on Twitter that show up where he is on certain nights. You can see some videos of him on his site HERE.

I've been in line for his pizzas, half a block, 45 minute wait (but while they were good, my LBE pies are better...!)

Offline siouxerbrewer

  • Registered User
  • Posts: 23
Re: Concrete recipe for Weber mod?
« Reply #23 on: August 22, 2012, 07:15:39 PM »
I know I'm late to the conversation but I'm a newbie to this forum and pizza making in general.  That being said the "Frankenweber" or "Pizza Forge" is what sparked my interest in pizza making.  I have scoured the forums to see how to build one of these things and I THINK I might have found the missing ingredient to the Perlcrete mixture and that is AIR ENTRAINMENT.  One of the main problems I keep reading about is that the when attempting to build a frankenweber the concrete is too heavy, it is not insulated enough, and requires too much refractory concrete for the relatively small build.  Also, in one of the "Pizzahacker" videos he mentions that the dome looks heavy but is light.  I believe that by introducing air into the Perlcrete (Refractory concrete and perlite) it increases the volume of the mixture without increasing the weight AND it adds strength and insulation.

http://www.australianperlite.com/perlite-concrete.htm (Perlecrete mixing guid)
http://www.fornobravo.com/forum/f6/deviant-design-6652.html (a possible recipe for Perlecrete with an air entrainment agent)

Very nice molding job meatboy!
« Last Edit: August 22, 2012, 07:17:30 PM by siouxerbrewer »

scott123

  • Guest
Re: Concrete recipe for Weber mod?
« Reply #24 on: August 22, 2012, 08:02:58 PM »
SB, perlite is basically stone popcorn.  It's almost all air.  Perlcrete contains loads of air.  This is what makes it so light.  It's this lightness that makes it an especially poor material for an oven, because it can't store and radiate back heat.

Pizzahacker has been through many oven permutations, and, honestly, I don't know what he's doing now.  I do know that he's making some amazing pizza, but, unless someone knows exactly what his present oven setup is, I continue to view perlcrete as a losing battle.


 

pizzapan