Oven on wheels

[cobblerdave]

Re: Oven on wheels

Gudday Mick
About those insulation batts......you can use them IF you have a fair insulation in place already to take up the big heat against the brick. My own oven has 2" of ceramic insulation and 4" of fiberglass batts and works real well. I took a section of the dome off and peeled back the insulation to check the temps during a good flash up. No problems. If you type in "Hi,new Aussie" in the search you'll find I put the readings I got in that post. I've since read of a couple ovens (not in forno resourses) use a layer of clay/straw then fiberglass batts.
Recon you might consider pearlite/cement over your dome because loose fill will have a tendancy to settle over time then stuff the rest of the enclosure with Batts.

Regards Dave

[wotavidone]

Re: Oven on wheels

My neighbours Socrates and Nia came over to visit today. Socsy was delighted with the oven. Told me all about the one his mum had back in Greece. Long time ago, Socsy has been in Oz since the late 1950's. Stone floor, terracotta roof tiles, and old bricks apparently.
Anyway, he told me to make the landing out front of the arch nice and big.
Yes I agreed, eager to show off my knowledge, you need to be able to park your dishes and stuff.
No, he said, to give you somewhere to rake the coals out and leave them in front of the arch while you roast your leg of lamb.
That way he said, there is no fire in the oven to burn the roast, you don't have a door so you can watch your food, and any air going in the oven is heated by the coals.
Socsy reckons his mate Mick, the Italian bricky, was always saying "Socsy, you buy da bricks, I build you da oven".
Sadly, Mick the Rat died before Socsy got around to buying the bricks.
So now I'm under orders to get the oven finished so Socsy can show me how to do Greek style wood oven roast lamb.

[wotavidone]

Re: Oven on wheels

I put the plug in, and rendered it with one inch chookwire. Sorry to the two Daves, one of whom said I wouldn't need the chookwire, the other who said I should use needles. In the end I went with the materials at hand - the guy I buy my chook tucker from gave me the end of a roll. He says he usually throws the last meter or so away, (its very tightly rolled and difficult to straighten out) so I could have it.
He did say something about not ruining his rep by telling anyone that he actually gave something away..........
Anyway the whole dome is covered, there are not to many shrinkage cracks, since I rubbed the whole lot all over with a wet rag as it went to that first setup stage and then kept it covered in wet sheets until it set fully.
If I can get home before dark one of these nights I'll photograph the finished job.
I'm now impatiently waiting for it to dry enough to risk starting the curing fires. I usually like this late autumn weather.............
Can't wait to get it fired, covered over and insulated, so I can get to the bit I'm really looking forward to - cooking!

[david s]

Re: Oven on wheels

It is a good idea to keep it moist for at least a week. I find wrapping it in cling wrap works really well. Ferro cement boats are kept moist for 28 days, but a week gives you something like 90% max.potential strength.
This is the hard part when you are itching to get fires into the thing.

[wotavidone]

Re: Oven on wheels

Itchin! Anyway I rendered the belt around the sailor course on Friday afternoon, but ran out of light, so I tarped it up over wet sheets to keep it "green", and finished the job Saturday morning. Its been tarped up until today, thursday. The belt around the sailor course is pretty much dry now, the dome is still wet, and there is always condensate under the tarp in the mornings, so it should cure real nice.
Itchin, but.

[wotavidone]

Re: Oven on wheels

Finally getting a fire happening. Have worked up from single sheets of newspaper to a couple of small hardwood sticks. Its amazing how much heat there is, when you keep it all in the bricks and let none escape. Dead bamboo makes excellent kindling, I've found. Smoke pattern is interesting - swear it does a circuit of the oven before exiting the door. There has been some discussion here on the forum about makinng these things more effcient. To be honest, I can't see how you could make a wood oven more efficient than these.

[cobblerdave]

Re: Oven on wheels

Mick
Slow down let the thing cure ....2 weeks then build it up....yer I know I cured mine 2 weeks ...then cooked pizza before insulating......but 2 weeks


Regards Dave

[wotavidone]

Re: Oven on wheels

Mick
Slow down let the thing cure ....2 weeks then build it up....yer I know I cured mine 2 weeks ...then cooked pizza before insulating......but 2 weeks


Regards Dave

Dave,
I let it go a full week before I lit some newspaper in it, and I then followed the FB recommendations - I'm up to 2 sticks on the fourth day. Old garden stakes - about 20mm x 20mm x 360mm long.
Too quick, you reckon?
Mick

[wotavidone]

Re: Oven on wheels

I'll definitely be slowing down the process now! I don't have the enclosure done yet, and this morning I woke at 3:30 a.m. to the sound of rain on the roof. So there I was in my Calvin Kleins putting a tarp over the oven in the dark. The dome wasn't too wet, the rain was just starting, but I'll be waiting a while before I risk another fire.

[cobblerdave]

Re: Oven on wheels

Mick
the cement itself has to cure rather then dry....yes if to wet, the pressure from the resulting steam of a fire is a problem. When cured build it up slowly so the stresses build up over time rather than putting it at full strain in one step. I was lucky to cook pizza after two weeks of curing but didn't take it to the 90 sec pizza temp rather 20 min pizza temp so no harm was done.
Yes you can cook in a uninsulated oven but watch the dome as it will get hot over time.
Regards Dave

[wotavidone]

Re: Oven on wheels

Yeah Dave that's why I thought I was OK - the greenest cement had had 7 days to cure, so I figured I'd just help the water evaporation along a bit. It took four days of heating and cooling to get to that fire in the photo.
Anyway - I'm not in a position time-wise to do anything more for a while - so it'll get lots longer to think about it before it gets another fire.
Talking to my consultant professional geologist/amateur potter yesterday, he says the danger point now is between 100 and 200 centigrade, probably the higher end of the range (I think), where chemically combined water must be liberated gently.
Only once though, he reckons - he says even though I won't get the clay to vitrification temperatures, it doesn't recombine with chemically bonded water once it has been driven off.
First priority is closing it in - flaming rain gave me the jitters this morning.
Mind you the poor buggers over the ranges in Wirrabara Forest would have been pleased to see it - the Parks people had a "controlled burn" that wasn't controlled at all - it got away from them the next day. Looks like its nearly out now though, can't see much smoke over the hills.

[cobblerdave]

Re: Oven on wheels

Gudday Mick
Whats doing?

Regards Dave

[wotavidone]

Re: Oven on wheels

G'day Dave.
Fired it this weekend to "bread heat". Well not really, it was measuring about 200 on the dome ceiling and 110 on the floor.
Couldn't help it, threw some dough in to see if I could cook a loaf. Nice crust, nice flavour, not cooked in the middle. Classic symptoms of low temps.
Still haven't fitted a flue or any sort of weather proof covering.
Cracking so far is limited to hairline cracks in the render. I only noticed them when it got a little damp from a dew one night and the cracks were the last bit to dry in the sun next day.
They spread to maybe 0.5 mm when the oven is heated up, so they aren't at all big. I was a bit stressed, until I saw some photos of cracks here on the forum that were waaay bigger. Arch seems fine. I'm not convinced these cracks go right through to the inner dome, they do seem to follow mortar joints, but the brick work seems solid and no smoke comes out of them. I'm thinking the bricks expanding more than the render. Without the insulation there is quite a large differential between the inner and out temperatures of the dome, which might explain things a bit.
The oven seems structurally sound when the dome is heated to 200+ Centigrade, so I'm not expecting catastrophic failure when I light the big scarey fire.
Regards,
Mick

[cobblerdave]

Re: Oven on wheels

Gudday Mick
Don't take you reading off the dome but rather off the floor.....after the heat has a time to soak into you brick and equilize a bit. Sorry I'm not a big bread maker but I'm learning but I cook a good roast or two. If you have now a fairly dry oven why not insulate...at the very least it will cover the cracks so you will not worry about them....


Regards Dave

[wotavidone]

Re: Oven on wheels

Insulation and flue are next. Finding the time is difficult. Lots to do, not much time. But I'll get there.
My weekly turn in the kitchen tonight. Made a big batch of dough this morning. Pizzas on the stone under the grill tonight.