Mr Gs Aussie Castable oven.

[david s]

Re: Mr Gs Aussie Castable oven.

Don't rush the curing. You can try the gas burner method which is much easier and ramps the temp up slowly and evenly. A 24 Hr burn with my burner takes the temp up evenly to 250 C then I go to wood fire for last two days to get to 400 C

[mr g]

Re: Mr Gs Aussie Castable oven.

Hi Jason, don't apologise for questions, we love them !!

The ovens have been doing well although we still haven't got a lot of data on their performance. My beach house oven is still at the stage of curing fires. I'm not there every weekend so I still haven't been able to cook in it yet although there might be some action this Sunday. One of my friends has had his one firing so hot that the floor tiles were glowing red and the oven held up beautifully. The refractory concrete we used is Vesuvius brand. I can get specifics for you if you need but I'm not sure of it's availabilty overseas.

The Internal diameter of the oven is 1000 mm and the height once the floor tiles have been laid down is 450 mm. The side walls are approx. 300 mm high. I made the walls straight rather than curved like a pure dome so that there is more room for things like roasting trays and the like. I wish I could say that it had to do with turblence and heating efficiency and so on but I just liked that shape. The design was a comprimise between a typical Tuscan oven and the Pompeii.

As for the curing process I got the feeling that following the strict method was going to be impossible for me and it may also a way for the refractory producer to cover themselves in case of product failure so I just used the "slowly increasing fire method". So far so good.

Good luck with your build.

Regards,
Mr G.

[jbriggs]

Re: Mr Gs Aussie Castable oven.

Mr G.

How have the ovens been doing?? I plan to do almost the exact thing that you have done, thank goodness I found this site!!! I have found a Harbison-Walker distributor that has everything that I need for a very reasonable cost. What castable did you use??

Also, what is the I.D. of your oven and how high are the walls/dome peak? Did you choose to angle the sides slightly inward to closely resemble the soldier course on a brick oven and allow less turbulance?

Did you strictly follow the curing process or did you find that simply lighting gradual fires until your were comfortable "letting all hell break loose" was suffcient?

Sorry for all the questions!

Thanks! Jason

[mr g]

Re: Mr Gs Aussie Castable oven.

Good luck ecoscapes, keep us updated and post any photos you have.

[ecoscapes]

Re: Mr Gs Aussie Castable oven.

Mr. G
Thanks for the info! I am hoping to get started on my oven in a couple of weeks. I am going to cast the oven first, then mount it to a trailer later. If anyone else has any experience with castable WFO on a trailer and would be willing to and any input I would very much appreciate it! I do landscaping and usually get a odd job in the winter when everything is frozen here, but no one has any work so I going to build a WFO trailer instead!!

[mr g]

Re: Mr Gs Aussie Castable oven.

Just an update on my castable oven :

I set the vermiculite based of about 1.5" plus two layers of 1" cal-sil board.
I then put the oven together insulated it and tried a small test fire. There are two layers of ceramic blanket and in the end there should be around 2" of vermiculite. All seems fine so far.

[Johnny the oven man]

Re: Mr Gs Aussie Castable oven.

Fibres are made from Polypropalene Mr G.This is ,as you would know ,"plastic" so it burns out at a low'ish temp.

[mr g]

Re: Mr Gs Aussie Castable oven.

HI David, thanks for that. Do you know what the fibres are made of?

[david s]

Re: Mr Gs Aussie Castable oven.

Mr G,
The fibres in the castable refractory don't actually add any strength at all. They are designed to burn out at around 160 C leaving minute "pipes" in the castable which water can find its way to and then travel to the outside. It reduces the incidence of steam explosions and cracking. If you want to increase its strength you need to add stainless steel needles (about 2% by weight)

[mr g]

Re: Mr Gs Aussie Castable oven.

Hi ecoscapes, I forgot to mention that I have poured a hearth slab. Photos to come soon.

[mr g]

Re: Mr Gs Aussie Castable oven.

Did you design the shape of the oven yourself or did you copy another design. How thick is the a profile of the oven. Did you pour the hearth as well? I am hoping to make one of these and put it on a trailer or truck. I'm wondering if I could or should put a metal mesh or grid in the casting of the oven to make it more durable, if anyone know?

Hi, the dome design is my own although I modeled it on some pre-cast ones I've seen either in person or on the net. The thickness of the oven is 70mm-75mm thick. You wouldn't really want it any thicker because of the longer heat up times. As far as strength goes I don't think there'll be a problem. The castable is extremely strong. The stuff I used has small fibres in it to add extra strength. There are also stainless steel needles available that can be added to the castable mix for extra strength but I don't think it's necessary.
Check out Joey Valderrain's project, he also made his out of castable and has it on a trailer.

http://www.fornobravo.com/forum/f43/my-cast-refractory-oven-build-7866.html

[ecoscapes]

Re: Mr Gs Aussie Castable oven.

Did you design the shape of the oven yourself or did you copy another design. How thick is the a profile of the oven. Did you pour the hearth as well? I am hoping to make one of these and put it on a trailer or truck. I'm wondering if I could or should put a metal mesh or grid in the casting of the oven to make it more durable, if anyone know?

[mr g]

Re: Mr Gs Aussie Castable oven.

Finished castable dome pictured. Overall there are not many things I would do differently apart from perhaps making the side walls verical as Joey Valderain has done for ease of making form work. Other than that I/we are very satisfied with the way they came out. Although I don't think I would cast ten domes at my place again.

One of the guys got busy and set his oven up on a steel frame in a few days and has got to the point where he is cooking pizzas in two minutes. He lit around half a dozen small curing fires beforehand though and there was lots of steam and water coming out of it. Now that his confidence is high with the oven he fired it so hard that his pizzas caught fire in about 15 seconds (a lesson in what not to do) but it shows that the oven can get to high temps with no advers effects. Currently it is taking him around 1 1/2 hours for the oven to get to pizza temps but we need more firings to see how quickly it can be brought up to temperature but I suspect it won't be much quicker than this.

Note, I haven't mentioned it but fyi the walls are around 70mm-75mm thick and there are 12 1/2 - 13 bags of 25kg castable in each oven.

Cheers
Mr G

[mr g]

Re: Mr Gs Aussie Castable oven.

Here are some photos of a completed dome and entrance. I tended not to take photos during the puring process because there was a lot of dust and I didn't want to subject my camera to this. There wasn't that much to see though. We mixed the stuff in the mixer, poured it into the barrow and shovelled into the form. The vibrating tool (which was just a kango hammer drill with a spade type bit on it) worked extremely well.

[mr g]

Re: Mr Gs Aussie Castable oven.

I separated the entrance from the dome to make for much easier casting. I'm not sure why I didn't think of this from the beginning. There was no need to make the sand mould in one piece. I also settled on a clever little idea to keep the form in place and with the correct slope. The side wall had to be cut to allow for an inward slope and rather than using timber stakes to keep it from bulging out once the concrete is poured we used a tie down strap that goes all the way round the form. Hopefully the pictures clarify what I'm babbling on about.