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I'm about to start building a flat bed glass kiln after using a ceramic kiln for many years. i will be using fibre for walls and roof, brick floor backed with fibre. My question is how big can i make it ! I have only 40 amps 220v available I need to be able to reach 1850f. Any help on working out sizing would be really appreciated.
Michael

You can get info in Glassnotes and A Glassblowers Companion.

http://www.glassnotes.com/

http://www.joppaglass.com/

The link below shows a kiln I built. 3x5x1 inside dimensions for a volume of 15 cubic feet. It draws 56 amps. I have it on a 70 amp circuit. You don't say whether you mean a 40 amp breaker or that you can use a full 40 amps. To use 40 you would want a 50 amp circuit. I tried using a 60 amp breaker and it overheated and failed after one test firing.

Jack

Michael wrote:I'm about to start building a flat bed glass kiln after using a ceramic kiln for many years. i will be using fibre for walls and roof, brick floor backed with fibre. My question is how big can i make it ! I have only 40 amps 220v available I need to be able to reach 1850f. Any help on working out sizing would be really appreciated.
Michael

Michael

I size glass kilns at 800 - 900 watts per cubic foot. Closer to 900 is good. I'm told that 700 works, but slowly.

I cover my brick floor with blanket and board and blanket.

In my estimation there is no good book on the subject. I'm working on one myself.

Bert,

I leave my floor bricks exposed where they're not covered by the fiber shelf or smaller kiln shelves.

I'm running very close to 900 watts per cf and the kiln responds very fast. (40 to 1650 in 50 minutes empty) Is the blanketing on the floor strictly for energy savings or there other advantages?

Jack

Jack Bowman wrote:Bert,

I leave my floor bricks exposed where they're not covered by the fiber shelf or smaller kiln shelves.

I'm running very close to 900 watts per cf and the kiln responds very fast. (40 to 1650 in 50 minutes empty) Is the blanketing on the floor strictly for energy savings or there other advantages?

Jack

I fire directly on the blanket with a layer of my powder. It makes for a fine one piece firing surface. I can control the texture by how much powder is on the blanket.

I seem to layer up stuff, blanket and board. I have some 1/4" Ld board, some 1/2" LD board that is carved, and a couple of layers of blanket. I figure that the more I cover the bricks, the less I have to pay to heat them and wait for them to cool. I take the layers out and put them in as needed. \

I buried my Giberson book somewhere, but doesn't he call for a ridiculously low watts per cubic foot in his big fuser design. Dudley is a blower not a fuser. I don't know why he put bad info in his book.

I use the element configuration that Henry calls Nijima. There is only a little bit of info usefull to fusers in his book.