Perlite/Mizzou castable

[david s]

Re: Perlite/Mizzou castable

I don't think it makes much difference whether you do drying fires before or after insulation, but I prefer to do it after insulating because you are not only driving moisture from the floor and dome, but also from the moist insulating layer. If you dry the dome and floor first you still need to dry the insulating layer after as well.

[mekdigital]

Re: Perlite/Mizzou castable

More images!

I removed the sand and it's rock solid! Unfortunately the plastic wrap I used seems to be completely 'melted' into the cement. Also where the wrap failed the cement and sand kind of mixed and I'm having hard time taking it out. I am more concerned for the wrap.

I am so noob that I did not mesure the sand dome, but it comes out to be 10" tall from inside and the arch happens to be 65% of that!

As for the bricks completing the arc: I can go with no bricks (but the chimney is a little bit exposed atm), or adding the two bricks either vertically or horizontally; In any case the idea is to hold them in place with that little piece of wood and pour the insulation layer on top - will it work?

help help

I am really proud of how it looks like!!!

[david s]

Re: Perlite/Mizzou castable

Is that piece of steel pipe designed to be your flue pipe?
If so, it is way too small in diam. IMO. I think you need to go to at 5" diam.Also I think you will find that it will crack your casting, because being heavy, thick steel it is going to get hotter quicker than the surrounding casting causing expansion and resulting cracking.
Regarding your two brick arch, I think you will need to fill the little V gap between the two bricks with some of your castable (no perlite added) to create a solid wedge, otherwise itvwill collapse.

[mekdigital]

Re: Perlite/Mizzou castable

I see the problem with the pipe and I feel so stupid! how do I get it out of there now without damaging the dome? :'(

is this pipe an overkill for me ? Amazon.com: Chimney 70902 5 in. x 24 in. DuraTech All-Fuel Stainless Steel Chimney Pipe with Galvalume Outer Wall: Home & Garden

if so, what's the suggested alternative?

thanks!!!

[mekdigital]

Re: Perlite/Mizzou castable

Or this? Water Heater Flue (Chimney)

[david s]

Re: Perlite/Mizzou castable

It looks like that pipe is really close to the front edge. I think you could get an angle grinder and carefully grind the castable away so you can remove the pipe. A double wall flue pipe is only necessary if you are going through a roof, single is fine. Can't see how big your dome is but maybe if it's really small you could get away with a 4" flue pipe, but no smaller.

[tinkerric]

Re: Perlite/Mizzou castable

Have you tried twisting the steel pipe and gently pulling/screwing it out, this might work.

You don't really need a chimney for the oven to work properly.

As David suggested, get some castable and make a wedge to hold the 2 bricks up. Or cast an arch. Or make an arch out of copper sheet, see my pics, and perlite over the oven and arch.

My copper entrance seems to be holding up, I fired the oven again last night. The perlite didn't steam this time.The oven burned white in 45 minutes with hardly any wood. Dome temp measured at 1050. I baked 4 pizzas and roasted veggies. 12 hours later the oven was at 195. I guess not particularly great performance, but it is a pretty low mass oven.
The copper expands and pushes down on the outside hearth bricks, so I will trim the copper or the bricks a bit.The perlcrete has one crack now but that shouldn't cause any problems.

I would keep your design simple and not bother with a chimney, design the chimney into your next oven.
Rich

[mekdigital]

Re: Perlite/Mizzou castable

I'll try to remove the pipe gently, but that castable is really a though guy! Once removed I guess I'll go without, it's good enough as first build!

Today at 2pm the dome was burning hot from the inside.. it really feels dry! on the other hand, the cooking floor is really wet.

I am overall happy!

[mekdigital]

Re: Perlite/Mizzou castable

I was able to get the steel pipe out of the dome, not easy: it took me one hour of grating with a tiny screwdriver and pulling and twisting - the good news it that I produced no damages. Thanks for saving my dome! I am now playing with candle size fires and it's amazing to feel the dome and the air getting so cozy warm quickly! Little by little I am understanding the errors in my design (like the cooking floor extending outside the dome!) but I'm positive I'll have fun with this thing. I already make unbelievable pizzas in my traditional oven.. I can't wait!

Fire Fire Fire !

[mekdigital]

Re: Perlite/Mizzou castable

This is how far we got. We're proud and ready to admit our errors.

[mekdigital]

Re: Perlite/Mizzou castable

I wish we knew what we were doing! We have been creating small curing fires, but we had the thermometer in the wrong position.. It was showing 200/250F, but when we moved to the top of the oven it bumped to 500F... We created some small cracks on the insulation, but the dome (that was already cured) is still perfect. How much should we worry?

[tinkerric]

Re: Perlite/Mizzou castable

Don't worry about the cracks in the insulation layer, it isn't structural.
But do follow the proper l curing schedule for the mizzou dome.
Rich

[busboss]

Re: Perlite/Mizzou castable

Any update on this one?

[mekdigital]

Re: Perlite/Mizzou castable

Hello !

Well, after about a good year of intense use we decided to move from San Diego to Portland and the oven was donated to some friends that participated in many pizza parties! It was not not possible to move it without damage, the insulation crumbled as the track drove the several miles between our backyards, but the dome was intact!

It was then patched and it has been serving pizzas three years strong!

[Greenman]

Re: Perlite/Mizzou castable

All's well that ends well! Hard to turn your back on good work.