fraser stewart

Cristobal Cristo wrote:Fraser,

Double core will be very impractical. I would try building a 25 cm batch box with shortened riser.
Is your core hot to the touch on the outside when reaching 640 C in the kiln?

The core is warm. Comfortably warm. So there is some heat loss there which could be grabbed by insulating the core.

A 25cm batch box would out 8.6kwh, (according to batchrocket.eu)
This little kiln is a 3kw kiln when electric. So with that logic a 20cm (meaning 4.4kwh) would do it.  I dont know if its correct to think of it like that or not?

What would happen with a 20/25cm core, connected to a kiln with a 15cm hole and flue? That will choke the stove right? by making it 20/25 I would use almost the whole kiln as a flue and have no room left over.
The flue could come out the side of the kiln i guess?

does anyone know if a double shoebox follows the same power output. this could be a simple build at that size?
Are there any sketchup models that are made for large batchboxes than the regulare 150mm.

Glenn Herbert wrote:No matter the size of your firebox, a pottery kiln will need to be fired without interruption from start to finish. Not just back to back firings, but reloading before the fire burns all the way down so heat input never falters.

You also need to be able to start the first fire slowly so the kiln temperature does not rise too fast and explode the pots. That is a matter for control rather than capacity, though the larger the firebox compared to the kiln the trickier it is to meter it. In my wood fired, cob-built kiln, I start the fire in front of the firebox and gradually over the course of an hour or so move it inside for gentle temperature rise. The firebox is about 4' long and 16" high and wide.

Hey Glenn

I went to see if I could find more info on your kiln. But the website on your profile is not available. Is there info somewhere else?
These are questions I had aswell.
As to controlling the burn.

I had three ideas.
complex ideas

Idea 1
Imagine that you have two fireboxes which can be slid into position. you can Load one and then when it's doing slowly alternate to the other one and back and forth.

you can then step up the wood amount to reach desired temp. you would also have double the wood.

Idea 2

Double shoebox, twice.
with two double shoeboxes based on 150mm system.
would make 2x1.9kwh
3.8kwh
The original kiln was less so I am guessing that the temp could be reached.

Only I am almost certain that heading these into the kiln through the same entrance of 150mm would cause an issue.


Idea 3.
I found a vid from Uncle Mud.
A simple Jube design means you can add wood and raise the temperature manually. sort of.
In this video however he is working with bigger kiln and chimney so perhaps needs that size to reach the 2100F/1150c temperature mentioned in the film

perhaps simple is sometimes better.


what do you think?

So I am hoping someone in the community can wade into this and help me with understanding this. I am not sure of which step to take.
I'm not an engineer so please don't kick me down.

So reading on batchbox.eu (website from Peter van den berg) the 150mm has a 1.9kwh

the dimensions are calculated for the batchbox.
a base measure, (the diameter of the chimney). For example 150mm. From this 150mm, one is able to calculate the size of the box, Height Width Depth.

From talking with Matt Walker, increasing the size of the batch box, ( making it wider) will have a detrimental effect on the air flowing through the stove. based on these measurements. I'm sure that all the testing for this has already been explored.

My question is. Does extending the length of the firebox so that more wood is able to be burnt have an effect on the power output?
I.e does more wood in the firebox make more BTUs and raise the temperature higher?

Would multiple burns.  one after the other before the stove cools substantially be able to add more heat?
Or is it limited to the volume of space in the kiln.

The core could of course be scalled up but then I would need a large kiln so....


Do I need to make a Hybrid wood and gas to reach those temps.




O

Cristobal Cristo wrote:That's much better result, but still too low. You could try wrapping the core on the sides and the bottom with some insulating material, but I think it will not be enough. You already have IFB bricks so you could try to build a 25 cm batchbox and see what happens. If the temperature rises to much more than 640 C then you will know which route to take.

do you mean increase firebox only and leave all the rest as a 150mm/6" system
do  you know the detentions for a 25cm firebox? or where I can find out..

test of new core and chimney.

640c
1174F.

update on chimney and firebox.

The port at the back of the firebox is suspiciously smaller than I expected. Is this correct or did I get something wrong

Does the BTU increase if the firebox is extended out and longer pieces of wood could be added.

There are probably some huffs and puffs and shaking heads out there.

but needed to ask

this is my new insulated core.

so guys. I heard the advice given.
I know that the temperatures I am aiming for will be a challenge but I think I have the time and will power to try and perhaps fail. Or perhaps something comes of it. I will see.

Today I returned to the store where I purchased the bricks you see in the photos.
I asked if they had low density fire bricks. very light weight.

And they did. they also had a dented double insulated stainless pipe. which incould buy for 10euros. so I will be doing some testing and adjusting with this new material

Phil Stevens wrote:Wrapping the core in CFB will help - not as much as using insulating firebrick but at least once the core gets up to operating temperature it won't be shedding so much heat. That would be a lower cost interim solution and might even do the trick.

as I stated, cfb is not available here.
would ceramic fiber blanket suffice?

Fox James wrote:I think you would stand more chance with a 10” batchbox and a step ladder.
Vermiculite board might be available to you as it is widely  available in Europe, it would certainly last long enough to do some testing but might not last long term.
I am all up for experimenting and I really hope you find some success but  I think there are better ways.

just curious what you do with the step ladder?
What are the "better way".
please share