Question on floor bricks 2

[yarex]

Am building 36'' inner size oven. My questions are following:

1. What should be the distance to inner Arc from cicle center? (see image).
2. I'll have a mix of sand and fire clay under floor bricks, but shouldnt i mortar the most outer floor bricks? Wont they move under weight vertically or horizontally when there is just sand/fireclay under them?
3. Can i use just normal full bricks and flexible tile mortar to entry arch? (distance from inner arch will be 12'' and just arc bricks would be normal full bricks, the rest would be fire bricks)


thank you.

[Toomulla]

The distance you refer to is decided by the width of the opening, decide on the opening width establish the right angle from the centre and go equal distance either side
If you are going to set the dome on the floor the thin bed of sand and clay will not matter
You can use normal brick for the outer arch work, I would not use flexible tile mortar they usually contain latex rubber which will break down when used externally

[yarex]

The width of the opening is what forno plans recommend - 19''. In that case i'll just draw it and see how far its from centre

[UtahBeehiver]

More importantly is that the the inside edge of the arch opening, in your case 9.5" each side of center, intersect the inside diameter of the dome. This ensures that the inner arch is in the correct position forward and aft.

[JRPizza]

Here is a side sketch of the top dead center inner arch brick sitting on top of the door opening, in my case @12.25 inches. You can verify this by placing the brick on top of your arch form and using your IT like Russell said to make sure the brick is going to be between the inner and outer surfaces of the dome, or it won't want to come out round. You can ignore the numbers in black - they were just measurements I was taking with my cad program to see how much arch I would have sticking out from and into the oven.