First time 42" oven build

[Gulf]

Yes, there is a way to figure the exact placement for the face of the inner arch. You may want to use the key words “arch placement” in a search of the forum. Also, there are lots of (42”) build threads. Read through a handful of them. By doing this you may find a lot of valuable information that you haven’t even thought of yet.

[Gulf]

You may also want to think about elevating that vermicrete and providing some drainage.

[mokomon]

Thanks for the info

[mokomon]

What are the pros and cons of opening shape . All curved or straight sides for 4 or so bricks up and then arched ? I am building on vermiculite concrete.

[JRPizza]

I'm a fan of the semi-circular arch as I think they look best and they distribute the weight so that buttressing (supporting the sides to react side load) is usually not needed.

[mokomon]

Have my vermiculite concrete poured. Fairly porous looking, maybe not level enough for the floor bricks. What should I do to make a real level surface ? Mortar mix ? Also , when I start my 1st row of dome bricks , are they just mortared to the next brick in the row or to the vermiculite insulating concrete aswell ?

[MarkJerling]

A layer of fine compacted sand works well for leveling a floor.
Some say you need not / should not mortar the first layer of bricks down, but I mortared mine, and it worked fine.

[mokomon]

Picked up my fire brick yesterday.The fire clay they sold me is..Moldit X Castable Refractory Cement. Is this the right stuff to use for my mortar mix ? I believe it is made by Vesuvius.

[mokomon]

Here is the info on the Moldit X

[Gulf]

If you are going to make 3-1-1-1 home brew, no it is not.

[mokomon]

Is this Moldit product more like stuff you would use and mix with water and use in place of the 3-1-1-1 ?

[mokomon]

Found some Lincoln 60 Fire clay at a local pottery supply. Will that work for the 3-1-1-1 mix ?

[Gulf]

I believe so. Though, I have no experience with anything labeled as a “castable”.

On the Lincoln 60 “fire clay”, I believe it will work. However, I really don’t know much about pottery clays. My experience in buying a reasonably priced clay is that which is sourced from from brick yards.

[Gulf]

The two fire clays that I am familiar with are packaged by MC Muddox and Superior brands. 50 lb. bags around $24 a bag the last I bought.

[mokomon]

Thanks I will see if someone has that