furnace/forge ceramics/insulation/hotface questions

[bigegg]

I've got a couple of projects to do in the next couple of months - a rocket stove bench for the garden, and a furnace to melt brass.
My last furnace was made using a terracotta chimney pot with perlite insulation, and didn't stand up well to the heat of an oil burner.

I have access to nearly pure white kaolin fireclay (about 2ft down in my back garden!) which I could use.

I can get fire cement for about £15 for 25kg locally.
Perlite is 16 quid for 100l just down the road.

I've been reading up on what to use as the ceramic liners for this, and am hitting the us/uk translation "brick wall" as to what "castable refractory" is - and where to obtain it locally to South Leeds.

I *think* it's "fire concrete" - ie, fire cement mixed with grog (crushed pottery/pre-fired clay).
Would I be correct in this assumption?


To buy "castable refractory" (as sold on ebay under that description) is £££ by the time I've paid carriage from the other side of the country - something which I'm reticent to do if I can make it from locally sourced stuff. I can't find any other source for it - is it called something else?

Ideally what I want is a 1/2" hotface made from fire cement or fireclay, then a couple of inches of "castable refractory", then a 2" ceramic wool insulating blanket, all neatly contained in a 1/8" steel shell

Does anyone have any suggestions?

 

[gaz1]

the one i have is this

http://www.castreekilns.co.uk/castable-refractory-56-c.asp

im bradford based theres also a place in lancashire that stocks it as well roughly around the same price

as goes for rocket stove bench i like this one too much as like the night light idea

though ive seen these

was after building this one but using the tech of the rocket burner using the method of vortexing round the crucible instead of straight up

an ingot and how many cans to get it

 

[bigegg]

the one i have is this

http://www.castreekilns.co.uk/castable-refractory-56-c.asp

That's what I mean by £££
25kg of fire cement = 15 quid
brick dust/grog is free
so, assuming 50/50 ( i have no idea? could be 3:1?) that makes 50kg £15 (or 100kg for 15 quid at 3:1)

50kgs of dense castable is £32 + £15 delivery + vat = £56

Am I wrong in assuming that buying castable refractory is like buying bags of ready mix concrete from b&q? 4 times the price to save a bit of mixing?

 

[gaz1]

if you can get hold of firebricks that is the grog that they use just smash the firebrick up with a hammer or as suggested use firbricks as the outside skirt and use a fire cement mix as a liner fro the front of the crucible

 

[bigegg]

I just smash up housebricks for the grog - the bricks were made locally, and are not quite firebrick.

in the second video above, he says the bricks are cast from "refractory cement" - would that be "castable refractory" or "fire cement" or something else entirely?

This is the problem I'm facing - so many different names for similar things!

 

[sardine]

I have cast fire bricks for wood / coal stoves with the Castree kilns refractory, its good stuff, their price is half the cost of new Morso branded firebricks.

 

[gaz1]

stop being a skinflint and pay the 1600F for the extra 1.00 its nothing and much better at reflecting heat

i paid the 19.00 for the 1700F

no must be firebrick not house bricks its the old firetype of brick also found in electric storage heaters

these

http://www.ebay.co.uk/itm/Vitcas-Cl...340483?hash=item33b34a90c3:g:dT0AAOSwwpdW5CQ7

http://www.ebay.co.uk/itm/30-x-Fire...881238?hash=item1a15805396:g:Nv8AAOSwzJ5XYvxR

http://www.ebay.co.uk/itm/Used-Fire-Bricks-X-40-/252433398090?hash=item3ac633f94a:g:cYcAAOSwc1FXaZMG

the firebrick of new is different

 

[bigegg]

I'm getting somewhere now...

ciment fondue = high temperature cement in powder form

add water gives

fire cement = refractory cement - available premixed from b&q etc

mix 50/50 with crushed firebrick (grog) gives

castable refractory

mix in about 4x as much perlite gives:

insulating castable refractory.

 

[bigegg]

stop being a skinflint and pay the 1600F for the extra 1.00 its nothing and much better at reflecting heat

i paid the 19.00 for the 1700F

no must be firebrick not house bricks its the old firetype of brick also found in electric storage heaters

these

http://www.ebay.co.uk/itm/Vitcas-Cl...340483?hash=item33b34a90c3:g:dT0AAOSwwpdW5CQ7

http://www.ebay.co.uk/itm/30-x-Fire...881238?hash=item1a15805396:g:Nv8AAOSwzJ5XYvxR

http://www.ebay.co.uk/itm/Used-Fire-Bricks-X-40-/252433398090?hash=item3ac633f94a:g:cYcAAOSwc1FXaZMG

the firebrick of new is different

funnily enough, I have about 40 of those I pulled out of a skip last year

 

[gaz1]

i was after building one out of 2 designs one down to safety issues within reason and i like the video below for this but big enough to melt an engine head

the thanks goes to the original poster of the video sad to say the user has changed the rights to private on the video but i have a copy of it

so yet again thanks to the original publisher of the video

with the other one above wanted to combine them both to make a better one and someone wanted me to make it got all materials and they decided to get on with it themselves instead

i was also interested in using used oil using the babbit burner for this project

 

[sardine]

I posted not long ago saying I had found an unlimited supply of storage heater bricks, the general opinion was that they were pants as firebricks.

 

[gaz1]

I posted not long ago saying I had found an unlimited supply of storage heater bricks, the general opinion was that they were pants as firebricks.

they are pants as firebrick however as a heater brick they arnt therefore mixed as grog with firebrick they hold there heat for longer another coat of refractory cement on top of them and you have a system that holds its heat and also has refractory propertys

 

[julianthegypsy]

See, I always thought grog was largely rum based!

 

[gaz1]

@bigegg ive been reviewing the usage of engineering bricks as where i live the engineering bricks here are as strong as hell and ive never come across another like them

they are the birkbys red brick if your curious get loads round here

http://ukwoodfiredovenforum.proboards.com/thread/363/fire-bricks-pavers

from the above forum

If they actually are engineering bricks ( commonly called blues); then you wont have any trouble with spalling or exploding. My informant reckons they are fired at temps in excess of 1200 degrees ! As to their heat retention properties, I think they'll fare better than red clay house bricks but not as well as firebricks.
He also reckons that they were routinely used up till about 15 years ago in the local steelworks to line the furnaces.

I had some of these "ex steelworks" blues above a replacement window in my last house and ruined countless masonry bits trying to drill some holes for a curtain rail !

a post further down

the manufacturer (Ketley) to try to find some data on the "blue's" or "solid Staffordshire blue's"...but couldn't find anything on their refractory qualities.....but did find out they are class A engineering bricks fired to 1200 degrees....quite right Ian.

note these was used for pizza ovens

 

[vbottles]

Have you tried Sheffield insulation in stourton? They are a big firm that have most firms of insulation. But you may need to order by the pallet load it is not in stock.
Personally if pony up the money and do the job once and as good as possible. If you need to borrow a small furnace I have one that I'm not using at present.
It's a bottom of a 48kg propane bottle. Lined with 1" 1400c ceramic fibre with a 1700c castable lining. I made it to melt steel which has done using a blower running either lpg or oil.
Andrew

 

[bigegg]

Have you tried Sheffield insulation in stourton? They are a big firm that have most firms of insulation. But you may need to order by the pallet load it is not in stock.
Personally if pony up the money and do the job once and as good as possible. If you need to borrow a small furnace I have one that I'm not using at present.
It's a bottom of a 48kg propane bottle. Lined with 1" 1400c ceramic fibre with a 1700c castable lining. I made it to melt steel which has done using a blower running either lpg or oil.
Andrew

Thank you VERY much for the offer!
I dont "need" a furnace at the moment, but will "want" one very soon.
Need to make *something* - im an addict!

 

[julianf]

I dont know if youre aware, but im doing the same project at the moment?

My plan -

Not have an insulating layer - just dense castable.
Why? Simpler, and my fuel is close to free. People on the alloy avenue forum seem to think this will be ok.

Ill probably start with an A12 crucible. I was going to design the furnace to fit an A20, but my plans have changed a bit, and i dont think ill need that volume.
I might try to get the face thin enough to fit an A20 in my, umm, off-the-shelf shell, but im pushing it, diameter wise.

Ill be using a "kerosene" (biodiesel) burner (from a boiler) to start with, but might start adding veg oil later.

I dont need to be able to melt cylinder heads - i made a much simpler device for doing these (which i keep meaning to photograph) - basically a tube, with a mesh on the bottom - you load it with wood, set it alight, and chuck the scrap on the top, with fittings etc. still attached.

The alloy melts, and runs through the mesh, into a container of water below. It then freezes into handy to store pellets. All the steel fittings are kept on the mesh. Cheap and quick to build, and can handle large and unclean scrap. Its nice to use - chucking on a load of rough old stuff on the top, and emptying out a bucket of clean pellets at the bottom.

Obviously youre going to decrease the yeild, melting twice like this, with the pellets having a large surface area to volume ratio etc. but for convenience, its nice.


Tomorrow, im off to the steel yard to get a bit of tube - you may recall i was having issues getting one the right size, but ive got around that now.

 

[julianf]

ps.

i think that, for my face, im going to try smashing up a bunch of storage heater bricks, and then putting it in with commercial 1600c stuff.

 

[bigegg]

I dont know if youre aware, but im doing the same project at the moment?

My plan -

Not have an insulating layer - just dense castable.
Why? Simpler, and my fuel is close to free. People on the alloy avenue forum seem to think this will be ok.

Ill probably start with an A12 crucible. I was going to design the furnace to fit an A20, but my plans have changed a bit, and i dont think ill need that volume.
I might try to get the face thin enough to fit an A20 in my, umm, off-the-shelf shell, but im pushing it, diameter wise.

Ill be using a "kerosene" (biodiesel) burner (from a boiler) to start with, but might start adding veg oil later.

I dont need to be able to melt cylinder heads - i made a much simpler device for doing these (which i keep meaning to photograph) - basically a tube, with a mesh on the bottom - you load it with wood, set it alight, and chuck the scrap on the top, with fittings etc. still attached.

The alloy melts, and runs through the mesh, into a container of water below. It then freezes into handy to store pellets. All the steel fittings are kept on the mesh. Cheap and quick to build, and can handle large and unclean scrap. Its nice to use - chucking on a load of rough old stuff on the top, and emptying out a bucket of clean pellets at the bottom.

Obviously youre going to decrease the yeild, melting twice like this, with the pellets having a large surface area to volume ratio etc. but for convenience, its nice.


Tomorrow, im off to the steel yard to get a bit of tube - you may recall i was having issues getting one the right size, but ive got around that now.

Basically a cupola furnace then?
Im going for insulated simply because perlite is cheaper than refractory.
Plus the rocket mass heater needs insulating.

 

[gaz1]

ive been asked to build this again but like everything else they wont want to pay the price for the building of it its always i will give you something for it but no price has been arranged for it at the moment

i have considered building one a few times im thinking of the ones ive posted up on here im wanting something easy to use and then put away when not using it
so far already have 3 builders bags full of refractory bricks used in fire places the refractory mixture is easy to get the other material i have is vermiculite but you can only use that in its loose form as thats its iunsulative propertys being loose

its the crucible that i have no idea on the best size to use or the material to use for the crucible but i also like the ones above[/QUOTE]