New 36inch castable build in Brisbane

[brissie]

Re: New 36inch castable build in Brisbane

Thanks for the advice David s. I did have enough castable for 80mm walls. I was not sure how far it would go. 10 x 20 kg bags is about right. It was funny to work with. I bit spongy but did do the vertical start okay. I also went with your suggestion, to just use the sand mould. I did attempt a form work solution based on conical sections for the start of the dome, but found I could not bend the thin ply I was using. I could hove cut slits in the outer layers of the ply to allow it to bend, but your simple solution worked well.

I used a central spindle to make the sand dome, photos attached (thanks Golf for the idea) . I coved the sand with wet newspaper, and sprayed with can of vegetable oil to help with it, and the timber partitions removal. I divided the dome into 4 pieces for easy of moving to the final position and to allow for moment/cracking.

In the end I did not use the second stage scraper, as the dividers worked well, and gave a depth gage to work from. I poured the castable in the late afternoon as it was a hot day (mid 30's c), and used ice in the water to reduce fast setting issues.

[david s]

Re: New 36inch castable build in Brisbane

Well done. Using the same method you can now pile some more sand in front of the door to create the formwork for the flue gallery. Remove the door formwork first, and remember to create a rebate so you can fit an oven door against the opening. The flue gallery casting therefore needs to be both wider and slightly taller than the oven opening.After you've finished that you can remove all the sand.

[david s]

Re: New 36inch castable build in Brisbane

Calcium aluminate cement does not need extended curing like Portland cement. 24 hrs is all that is required. I always cover it after placement, but it can be removed from the mould, or the mould removed from the casting, in your case, the next day.

[vanoontour]

Re: New 36inch castable build in Brisbane

Have you put any form of reinforcing in or would the thermal difference cause issues?

[david s]

Re: New 36inch castable build in Brisbane

The preferred method of reinforcing castable is stainless steel needles.Stainless so they don't rust and needles so the heat dissipates easily to the surrounding refractory. Using thicker reinforcing is problematic because as heat is applied it goes to the much more thermally conductive material which then gets hotter and therefore expands more than the surrounding refractory. The needles make placement by hand more tricky. I often get stuck by one or two. You learn to handle the stuff with care.

[oasiscdm]

Re: New 36inch castable build in Brisbane

. The needles make placement by hand more tricky. I often get stuck by one or two. You learn to handle the stuff with care.

I was thinking about that ouch

[brissie]

Re: New 36inch castable build in Brisbane

Cast the flue assembly. Used 1.5 bags of castable.

[david s]

Re: New 36inch castable build in Brisbane

Yep, that's it. You've done well. I see how you've been able to keep the flue gallery nice and shallow. You will thank yourself for this when working the oven. Folk who make theirs from brick are unable to get it so shallow.They also take way longer to construct it being unable to create compound curves.

[david s]

Re: New 36inch castable build in Brisbane

Just checked the date when you broke ground, only ten days ago and you have the stand, oven and entry finished already. Brick builders seem to take months to get to this point.You are doing really well for your first oven.

How do you plan on insulating it?

[brissie]

Re: New 36inch castable build in Brisbane

David s, thanks for the encouragement, and yes It has been going well. I started 3 weekends ago.

Weekend time line:
Week 1) Dug the hole in the ground placed crusher dust, and poured the slab, stared the block base.
Week 2) Finished block base. During the next week added hebel boards for the top.
week 3) Completed oven dome and flue structure.

I was a Plumber, but left the trade 20 years ago. Trade skills help for sure. Being able to work with concrete, timber, and metals is handy.

I agree, if you take the brick route, its going to take a much longer time. Plus you need a proper brick saw for a considerable time. I purchased a small wet cut tile cutter, does 33 mm just enough to cut through a concrete block, and it worked okay for this project. You couldn't get away with tile cutter doing a full oven in bricks.

As for the insulation, I have 50mm Calcium Silicate board for the base, 7.2 meters x 600 x 25mm CF blanket, ad 3 100 litre bags of grade 3 vermiculite.

I plan on putting a gap between the dome and flue structure. I was planning on 10 or 15 mm gap using a vermiculite 5 to 1 or 8 to 1 mix between. Do you think this is workable? I will also cut a inverted V shape in the hearth doorway, with 2mm gap and the lower V filled with 10:1 vermiculite.

[david s]

Re: New 36inch castable build in Brisbane

All sound s good. I use vermicrete for the heatbreak gap too. I use 5:1 so it's got a bit more strength and holds together better than a lean mix. I use around a 10mm gap If you stuff some tissues in the gap at the top from underneath it will prevent the stuff from falling through until it has set. Get a thin stick and just compress the stuff in until it's full.

[brissie]

Re: New 36inch castable build in Brisbane

I have a question.

How hot does the flue assembly get towards the front and up say 200 mm?

The reason is I would like to put some light into the oven, for lighting the fire at night etc. I have read that it can be quite dark, and need a touch. I was thinking of using light - pipe, technology to relocate the light source away from heat. I would think heat resistant items, like either glass fibre bundles or silicone rubber tube, may work. Its just an idea I am tossing around. It may be easier to just use a touch.

[mikku]

Re: New 36inch castable build in Brisbane

Hey! You are really not a newbie to this type of work!

You have the whole thing down pat before you even proceed even 1mm!
It is nice to see a pro do his thing! You ask questions but you already know the answers a head of time!

You should do a video and put it on YouTube for this build! I am sure it would get a million hits!

Welcome aboard, I am sure you have a whole lot of things that you can add to this forum!

In the photos of the pouring of the base, which gentleman are you? Another geezer like me with a whole lot of history attached to his resume I would guess!

[mikku]

Re: New 36inch castable build in Brisbane

15 hits! Lets make you a Il Pizzaiolo or whatever Forno Bravo calls the top --big number count guys! Why go through the motions of a bunch of useless chatter to get to the pro level!

[stonecutter]

Re: New 36inch castable build in Brisbane

Why go through the motions of a bunch of useless chatter to get to the pro level!

That's why it doesn't matter......