My first WFO build thread... I'm torn clay/cob or the much discussed homebrew cast

[Alomran]

Just be careful, a clay chimney pot is designed to sit at the top of a chimney, not at the bottom. Because it will see much higher temperatures closer to the fire it will crack unless you insulate around it.

David, you are a true WFO encyclopedia, you seem to have accumulated knowledge at the smallest details.

[hughjamton]

Hi Robard & Hattori,

I have found this cheap UK fireclay supplier https://www.castreekilns.co.uk/ They are selling


one Fireclay - 25KG - 25KG Bag
£10.00

Fireclay - 25KG - 10 X 25KG Bag= 250Kg
£80.00

Fireclay - 25KG - 40 x 25KG Bag= 1 Ton
£180.00


Cost of ''Standard Delivery'' Zone

UPTO	25KG	50KG	75KG	100KG	125KG	250KG	500KG	1250KG
	£8	£15	£22	£29	£36	£40	£45	£50

and it's worth comparing their prices to other suppliers you have reached out to.

There is also another cheap supplier for brand new firebricks https://www.kilnlinings.co.uk/specials, their fireclay is more expensive than the first one, but shop around and have a look!

I know of a guy in Essex selling the double size firebricks blocks that have been sitting in his barn for years for a good price (I think £3 for a double size brick and he may have about 150-200 bricks). If you are willing to travel to collect from Essex and willing to cut them to your required sizes, let me know!

I do have few bits and pieces left from my ongoing hideously, out of control, over-budgeted, 6 years ongoing, gigantic oven project, perhaps the largest ever pizza oven in the entire UK's history and may be it will be the least used oven in the history of mankind!I had in my mind using it for a good cause to cook for the homeless in London.

If you can get to Weybridge in Surrey, I am happy to donate Pumice, Vitcas fireplace render buckets, few firebricks (approx 20-24) as well as a sack of fire cement and perhaps a sack of fire clay. Let ,me know.

If you need to have a chat on the telephone, you can message me and I can give my mobile no.

Keep up the good spirit and build as big as you can, don't cut corners as you will end up paying twice as much!

Cheers.
Mustafa

Good find on the fireclay Mustafa, unfortunately they are out of stock at the moment, I'll have to wait for them to get some more in as they are by far the cheapest I've seen, especially when you take postage into account.
Keeping the cost down is really important to me, for various reasons we've taken early retirement, so we're living off of our savings until my pension kicks in in a couple of years.
Her in doors isn't too happy, it's classed as an unnecessary expense, so I'm buying as much as I can from places like facebay and the like to prove it can be done for minimum cost.
I don't mean to hijack the thread, I'll be starting my own homebrew story shortly, I've prepped the ground ready to start the base, it might just take a while to get the gear together at the right price.
Thanks again for the fireclay tip.


Cheers
Martin

[Robarb]

Just be careful, a clay chimney pot is designed to sit at the top of a chimney, not at the bottom. Because it will see much higher temperatures closer to the fire it will crack unless you insulate around it.

Thanks david s , can you insulate it with the same vermicrete mix on the inside and the blanket/vermicrete mix on the outside (just the nit where the chimney meets the galley, or all of it?)

[david s]

The problem is the temperature difference from the inside of the pipe to the outside, one hot the other cold and the thermal shock can’t take it. You don’t need to insulate inside the pipe. An inch or so of 5:1 vermicrete should do it, over which you can render. Can’t say how high you’d have to go, but guess around 400 mm should be sufficient.

[Robarb]

Thank you!

Anyway, unless i can get my way, the wife thinks a stainless steel flue pipe looks better....

[Alomran]

Good find on the fireclay Mustafa, unfortunately they are out of stock at the moment, I'll have to wait for them to get some more in as they are by far the cheapest I've seen, especially when you take postage into account.
Keeping the cost down is really important to me, for various reasons we've taken early retirement, so we're living off of our savings until my pension kicks in in a couple of years.
Her in doors isn't too happy, it's classed as an unnecessary expense, so I'm buying as much as I can from places like facebay and the like to prove it can be done for minimum cost.
I don't mean to hijack the thread, I'll be starting my own homebrew story shortly, I've prepped the ground ready to start the base, it might just take a while to get the gear together at the right price.
Thanks again for the fireclay tip.


Cheers
Martin

Hi Martin, I have sent you my telephone number in a private message, you can give me a call if you like.

[Robarb]

Well, I've bit the bullet, made the measurements, checked and double checked and all materials are now ordered and en-route.

All in for a 70cm internal diameter oven i've paid roughly £435.00. That includes:

Sand
Clay
Cement
Lime
Fibres
Needles
Concrete lintels
Twin-walled flue
Firebricks
CaSi boards
Vermiculite
Insulating blanket (superwool)


Just need to source some 'free' chicken wire, some off cuts of ply for a gallery frame and borrow the in-laws tools

Also need to decide on a final coating whether that be a stucco render or some form of tiled finish.

Lets hope the weather plays nice

[UtahBeehiver]

Pretty cheap by most WFO build costs.

[Robarb]

Yeh, The base build has been free apart from the concrete lintels as i've sourced free stuff from Faceache marketplace. I got a great deal on some CaSi boards and blankets that were unused offcuts (there's enough for what i need), and I bought a 1m long 150mm wide twin-walled flue for £25 instead of the usual £60ish.

I got lucky with building supplies too, i have a brickie mate who put me in touch with the builder yard he uses and they are roughly 10% cheaper than others nearby. Really chuffed with my flue buy!

There's a few odds and sods to get but i reckon it'll be about £500 once finished. If i build it right with all the knowledge you guys have given, i'll be well chuffed!

It's surprising what's out there for free or cheap when you start digging around

[Robarb]

Just out of curiosity, could you mould the gallery entrance out of wet and, similar to the dome, without the need for a wooden frame? I have pretty decent modelling skills....

[UtahBeehiver]

That's a question for David S, he is our casting expert.

[Robarb]

david s Thoughts? (no rush). My stuff won't be here for a fortnight

[david s]

Just out of curiosity, could you mould the gallery entrance out of wet and, similar to the dome, without the need for a wooden frame? I have pretty decent modelling skills....

yes, you can just make a sand mould covered in wet newspaper like the dome. Doing the sides is difficult because they stand up vertically. It would be easier to cast them separately and put them in place when set then do the top part. Or even easier use some bricks for the sides.

[Robarb]

So, i started

I cast my oven around the sand mould done and galley, and i did a one piece cast rather than separate gallery in the end. The cast was finished on Friday evening, i have had a wet tarp and plastic sheet loosely covered over it since then. It is now Sunday morning, when is the best time to remove the sand mould? There is still condensation on the underside I'd the plastic sheet and the tarp is still slightly damp (although not as much as it was on Saturday as it's been really hot here). Do i take the sand out today, then keep it damp for a week, or do i leave the sand in there for a full week of dampness?

The risk in leaving the sand in there is that i won't be able to inspect the inside until i remove the sand by which time crack recovery may be too late?

Thanks

[david s]

Strength will be enhanced by holding moisture in the casting for at least a week. The voids should be filled while the cast is still moist. A better bond will be created while the casting is still hydratingt, so you can remove the sand, fill any voids, but still keep it damp by covering it.