Finally decided on 32in castable dome

[Mullster]

mesoiam thanks for the encouragement

The gallery stands perfectly fine - I’m just worried about what happens when it starts to get hot? If it have cemented over the cracks do they get worse (my lack of experience here means I don’t know that answer).

Used every last scrap of the fire clay so will need to order more assuming I’m re-casting at least something. I also need to re-read up on what sort of substance to fill crevices with - can’t remember if that requires fire clay but I assume so.

[mesoiam]

Hi Mullster, Don't get too down. Does the flue gallery stand up on its own? Is it too much of a worry if it is cracked but stable? Will it not be OK once it is covered in vermicrete?
These are questions for more experienced member.
IMHO, and take that for what it is as a novice, I don't see why you couldn't cut it off with a grinder and have another go at the flue gallery. The dome should be OK as others have said it is an inherently stable shape, maybe repack with sand if you are worried.
I did the same thing with my entryway mould, big screws facing away from me, took me half an hour to carve my way in.
Would you have enough fireclay left for another flue gallery?

[Mullster]

More pictures

[Mullster]

Please learn from my casting mistakes.....

Its really hard not to be massively deflated after today. I’m back to work tomorrow so figured I would remove the framework and sand dome from my casting (4 days since casting day) hoping it would help the cure given we have damp weather forecast all week anyway.

Because of the way I had created my frame it was incredibly difficult to remove. Removing it contributed (I think this likely would have happened anyway) to my flue gallery cracking significantly. I don’t think it’s recoverable and will definitely appreciate the advice of the likes of DavidS
on how to move forward now. I suspect I need to cast a fresh flue gallery but as my original was all one piece with the dome I’m really worried about causing further damaging by trying to “cut it off”.

I’m also not sure about the quality of the dome. From the outside it looks great and solid and does feel robust. On the inside there are multiple crevices. I’ve read a lot of posts about filling in cracks etc - so would appreciate views on whether this is achievable for me or do I literally have to start all over again with the whole casting.....

Mistakes I made - please learn from these if you haven’t cast yet:

1. Using MDF for the frame - a ‘wood’ that absorbs water and then swells - I feel like punching myself in the head for that one
2. Screwing the frame together from the wrong side. Multiple parts of my frame were constructed with screws only accessible if you were in the dome covered in sand yourself.....2nd punch in the head
3. Lack of Patience - by this point I am more than 11 weeks into the build - I’m desperate to progress but on reflection casting my dome in 28 degree c heat goes against all the advice I’ve read on this forum. I don’t know if it has contributed, but looking at certain areas of the casting it feels like layers may have dried more than they should have before the next layer was put on causing the crevices?
4. Not following tips from others. I must have spent days of my life reading posts on this forum from seasoned oven builders, and those that are just a step or two ahead and although I’ve taken a lot onboard, I distinctly ignored certain tips even though I thought about following them. For example putting shims under the frame so it can ‘fall down’ a few mm for removal. Putting card around the flue mould - paint can in my case.
5. Casting all in one piece. I know plenty have done this successfully, but I am wondering if a 2 piece approach (flue gallery separate) might be advisable for first timers. It simplifies the framework and reduces the risk I am now faced with of potentially ruining my dome trying to remove my gallery.

Guys I’m sharing this hoping that anyone who hasn’t cast yet gets something from it. I wouldn’t want anyone else to feel how I did this morning when I watched my cast split in my hands, and realised just how many things I should and could have done differently.

I would welcome advice and views on my next steps which are going to have to be taken carefully!

[mesoiam]

Looking good mullster, I see you got caught out underestimating the dome sand as I had. Bag after bag was eaten up even with a load of bricks to fill the space. I've been working on the front part of mine while the cast dries out. Will get some pics up soon.

[sergetania]

Thank you Mullster ! I have seen the curved trowel. It looks handy. I have also looked up the flexitub In US, everything(from fishing to construction to homebrewing) is done with 5 gal buckets

[Mullster]

The cast looks great! Thanks for the pictures! Maybe I should relax and be less intimidated with this. Do you think you can post a picture of tools you have used and found useful? Only experience with concrete/bricks I have is pouring slabs. No idea what people use for even basic tasks. Thank you!

sergetania i bought this set and used both of the circled trowels during casting day - the smaller one for mixing and placing the mixture on, and the larger one for smoothing.

I do think a homemade curved trowel like a couple of the guys have shared would have possibly been more effective for the smoothing.

[Daveholdn]

Mullsterdavid s thanks very much for the info

[sergetania]

The cast looks great! Thanks for the pictures! Maybe I should relax and be less intimidated with this. Do you think you can post a picture of tools you have used and found useful? Only experience with concrete/bricks I have is pouring slabs. No idea what people use for even basic tasks. Thank you!

[david s]

Hi Mullster, looks great mate, I'm building 30" cast dome and currently just laid the vermiculite slab. I've sourced the rest of the material but with the sand form /Castle you made, do you have any idea how much you used? I've ordered 200kg of builders sand from MKM supplies up here in Scotland but a bit worried now as you said you used every last bit of your sand?

Cheers

Dave

Volume of a sphere 4/3 x pi x r3 (don't forget to halve it cause it's a hemisphere.
sand density is around 1.7 kg/litre
density = mass/volume

[Mullster]

Does anyone know if these “vitreous enamel” black flue pipes are suitable? They do refer to wood burning stoves and 600 degrees Celsius temperatures? Are they ok?
Id really like black rather than steel colored.

[Mullster]

Hi Mullster, looks great mate, I'm building 30" cast dome and currently just laid the vermiculite slab. I've sourced the rest of the material but with the sand form /Castle you made, do you have any idea how much you used? I've ordered 200kg of builders sand from MKM supplies up here in Scotland but a bit worried now as you said you used every last bit of your sand?

Cheers

Dave

Daveholdn Sorry I didn’t keep proper track but it was about 100kg I believe and as I said I stuffed as much other stuff in there as I could!

The dome is 32” internal so you’ll have less needed in that sense.

I didn’t mind too much - of all the materials on this project sand is just about the cheapest!

[Daveholdn]

Hi Mullster, looks great mate, I'm building 30" cast dome and currently just laid the vermiculite slab. I've sourced the rest of the material but with the sand form /Castle you made, do you have any idea how much you used? I've ordered 200kg of builders sand from MKM supplies up here in Scotland but a bit worried now as you said you used every last bit of your sand?

Cheers

Dave

[UtahBeehiver]

That would be good then all your post are in one place rather than spread out on other members threads.

[Hattori-Hanzo]

I need to start a thread soon, just got to organise and up load the photos.
The build is very similar to yours but I've used a course of fire bricks around the base of the dome then cast on top of them.

Are you after a single or double walled flue?
I got mine from eBay in the end as price was good.

I'll dig out the seller later.

Stainless flues seem to be a little more expensive