Mr Gs Aussie Castable oven.

[mr g]

Re: Mr Gs Aussie Castable oven.

Hi guys, getting the band back together. Planning on making another three ovens.
Hope to make an 800mm diameter oven for my parents and a couple based on my earlier design. I will make a few minor changes to the oven but it will essentially be the same design. I'll add some photos when I'm ready to go.
P.s - you move home and it's not that easy to take the thing with you hence the new project. Anyway , I love building the damn things. ��

[mr g]

Re: Mr Gs Aussie Castable oven.

Hi guys, I might have photos of the themometer installation but there wasn't much science to it. I simply drilled through the outer shell with a masonary bit without the hammer action and when I got to the inner refractory shell I switched over to hammer. I installed it beside the oven entrance so I could read it easily.
I haven't used any needles or certainly no re-bar. We have had a few ovens going now for a couple years with many dozens if firings with no cracking what so ever. The only thing I would change with the design is an 8 inch flue instead of a six inch flue.

p.s - I had no previous experience so if I can do it anybody can.

Cheers for now.
Mr G.

[Johnny the oven man]

Re: Mr Gs Aussie Castable oven.

add 2% by weight. Try Antec Engineering.FIBR446/25-C

2% is lighter than the normal 2.5% that is recommended for refractory work. I would be going higher, useing about 5%. there is a product called fibrestone, made by Sila in Perth that uses 60% s/s fibres. It is used for very high load areas. A high % wont hurt a dome.

[Johnny the oven man]

Re: Mr Gs Aussie Castable oven.

add 2% by weight. Try Antec Engineering.FIBR446/25-C

2% is lighter than the normal 2.5% that is recommended for refractory work. I would be going higher, useing about 5%.

[david s]

Re: Mr Gs Aussie Castable oven.

add 2% by weight. Try Antec Engineering.FIBR446/25-C

[Aussie Pete]

Re: Mr Gs Aussie Castable oven.

great ovens Mr. G, surely your not a novice at this, you've done a fine job.

I have a quick question, i am doing a castable dome also (over sand), i think i might add some stainless needles in my mix, does anyone know where to get around brisbane, or what kind of supplier to go through. is there a thread on here somewhere, that goes into more detail about them, (such as size of the needles & quantity in the mix).

Mr. G, do you have pics of how you transitioned your thermometer into your dome.

[david s]

Re: Mr Gs Aussie Castable oven.

The purpose of the fine fibres in the castable mix is not to provide strength because they melt at 160 C and then burn away leaving a network of tiny pipes that can safely eliminate steam.Some manufacturers use natural fibres that just burn away, others use polypropylene fibres that melt then burn. These are different to the stainless steel fibres that are added to provide extra strength.

[david s]

Re: Mr Gs Aussie Castable oven.

You could try rebar, but the recommended reinforcing is stainless steel needles, presumably for a reason. Better to stick with what's recommended IMO. Mild steel will be prone to rusting in time. High temp will accelerate any reaction and rusted steel expands in volume creating stress points and fractures.

[TapRackFire]

Re: Mr Gs Aussie Castable oven.

Great build Mr. G,

I am torn on how to do my dome. If I built one like yours, do I need to add rebar to it? Would that not make it stronger? I have thought of using a steel dome from a propane tank and covering it with refactory concrete, but having trouble finding a dome large enough.

[Johnny the oven man]

Re: Mr Gs Aussie Castable oven.

Refractory prices are still about the same, we sell Vesuvius 135 for $30/20kg bag, your right about 8" flues, the 6" is just that little bit small. Stainless steel "needles" should be added to make the cracking minimal, best to use it in the whole dome if possible.

[mr g]

Re: Mr Gs Aussie Castable oven.

Hi Rob, I think a one piece oven will be fine. I went with pieces because we weren't making them in the place where they'd remain (due to the number of ovens).

The bags were approx $35 each at the time but that was a big order so there was some discount available and it was 2 years ago.

The ovens are all performing beautifully with no problems. I'd give them a 95/100.
I would change a couple of things:

I would make the flue opening bigger - that is 8inches instead of 6inches. I expect that would help to minimise the smoke at firing up time. I stress that 6 inches is not a problem but 8 inches might just make it draw a little better when firing up.
I would also make the entrance a couple of inches lower to encourage the smoke up the chimney rather than out the front. This is only an issue at fire up time when it's smoky.
I would not change the door opening however. That is a perfect size.
I would also consider stainless steel needles around the entrance where the chimney gets quite hot. I have had some hairline cracks appear but it's no big deal. Other than those things the rest of the design is fine.

Cheers
Mr G

[robertjusher]

Re: Mr Gs Aussie Castable oven.

HI MR G
I am looking at the same idea for mine.
I have broken ground and hope to get the boxing done next weekend so am a little way off !!
I am going to do the cast dome (today's plan) as I am no bricklayer and don't want to cut bricks. I was thinking of 1 piece mound in place (sand mould)with SS needles to help hold together in case of any cracks. Any thoughts on a 1 piece mould, or is more going to be easier in the long run?
More questions...
How much did each 25kg bag of refractory cost?
How's the oven and the other 9 you made going.
Any thing you would change?
Thanks

Rob

[mr g]

Re: Mr Gs Aussie Castable oven.

Yep, local foundry in Kilsythe

[Jayson]

Re: Mr Gs Aussie Castable oven.

Hi Mr G,

I love you aluminium oven door. I live in Melbourne and am part way through an oven build. Where did you have the door cast. I assume a local foundry did it for you?

[mr g]

Re: Mr Gs Aussie Castable oven.

Vesuvius, which has the same specs as Silacast 145.