[Dutchoven]

Thanks for both of those comments
Your welcome!

In your case Acoma it seems as if you did everything pretty much by the book and still you got cracking so there must be plenty of others out there who had this too. Very nice job on the oven too I checked out the pics.
I agree nice job Acoma!
I don't know whether refractory cement and firebricks would have cracked just as much. Does this still need the 7 step firing? IMHO all ovens should get slowly ramped up to temperature primarily because of the steam issue...a good refractory cement is calcium alumina based and withstands the heat and cool cycles better so...it sounds like in the beginning most mortars will react the same...but I have heard it said "if it's brick it will crack
I think the initial casing with no crack cement should indeed have had a slip layer as suggested by Dutchoven, but I've ordered the blanket as suggested. I think it will be OK anyway...physics and the fact that you burn the oven so hot and complete even if the crack is visible inside there should not be any issues...this oven will have a bit more mass to heat up but with good insulation it will perform very well...you should take a few pictures
I installed a small oven kit recently that had needles set in to the cement, I wondered if anyone has tried this instead of fibres to prevent cracking? Stainless steel needles are used as reinforcement much like rebar in reinforced concrete...ovens like that will usually not crack because they are made from fewer pieces and each piece is more homogeneous(sp?)

All the best!
Dutch