This does presume a three inch thick crown and I do think thicker might be better, by one inch. Mass is important in electric furnaces although it is a tradeoff with strength. The brick does just sit in the well.
My castable will be Morocast 99 % alumina. II was really impressed with the Morocast 95 and Tom suggested I try this stuff too. I will be using 18 inch by eighteen inch by one inch paver tile from Engineered ceramics as well.
This furnace will open from the side with a giant refrigerator door to remove the pots.
