Lip on dome bricks using a tramell

[mongota]

You want the "L" (green line) that cradles the brick to cover more of the inside face of the brick so that your trammel arm (red line) is centered on the face of the brick.

[Giovanni Rossi]

Sorry Ted, I've been away. rsandler already gave you good direction and clarified my earlier comment: "AND, the center of the trammel shaft must line up in the middle of the dome bricks to achieve a hemispherical dome."
The guys who have built proper ITs (trammels) are very clear that you need to be able to visualize a straight line from the pivot point at the floor through the shaft to the mid point of the inside face of each brick, both vertically and horizontally. Otherwise, each course will be out of alignment with the last.

As far as your floor under the dome, I'm not the best source of info as my floor tiles were mortared in place. I'm not quite sure what you mean by "loose". But, from what I've read on this forum, as long as you've used enough dry sand/clay mixture to be able to get your bricks level and seated well (not rocking) under where your dome rests you should be fine. I've seen some builders recommend using a 3/8" - 1/2" notched trowel to apply a proper amount of the bedding. The weight of the dome will help to hold the bricks in place.

I'll add to david s 's comment about how wet to make the bricks. I had good success with soaking my bricks for at least 15 minutes. When I was ready to lay the next group, I would lightly dry them and rest them in place on the dome. This allowed some water from those bricks to drain and dampen the bricks underneath. This keeps the bricks already in place from pulling too much water too quickly from the mortar.

[TEDFB]

Hey guys
I am really grateful for advise and help, I am going to get stuck into this lot today and will give you an update on the progress,
Have a great day

[rsandler]

Back on the trammel question, you need the pivot point of the trammel to be centered vertically on each brick. From your picture, it appear that the pivot point is in line with the top of each brick, leading to the substantial ledges in the picture. Lots of ways to get that offset; here's a picture of the one I built for my second oven. My bricks were 2.5" thick, so the bit of angle iron that the top of the brick sits against was 1.25" above the pivot on the castor.

[david s]

The bricks should be moist rather than wet. Avoid water sitting on the surface of the brick. In order to get a good bond the brick needs to suck some water from the mortar. A totally soaked brick, especially with a further film of water on its surface will not allow this, so just totally soak the brick then give it a few minutes to dry a little.

[TEDFB]

Mmmm the questions are building up..
How long after soaking the dome bricks can I start building with them, and then how long can I build with them before I need to soak them again.
Hope I am not being too much of a pain

[TEDFB]

Hi Giovanni,
Did you have any take on me building on my floor that has a few loose bricks, as the dome just rests on the floor
Best regards

[TEDFB]

Hi Giovanni
I have got my Email and web sites cross wired hope this works

[Giovanni Rossi]

I'll jump in since no one else has yet. Pictures would help. If you set your trammel so the inside of the dome is at the bottom of the soldier and you used a true soldier (i.e. 9" high), it stands to reason that the next course would line up inside of the top of the soldiers. You'll need to adjust the length of your trammel now that the soldiers are in place.

Also important is the position of the shaft of the trammel. Do a search for IT or indispensable tool and you'll find a lot of good info from the experienced builders who have made their own tools. You'll see that it's important to have the pivot point at the center of the floor as close as possible to the final floor height. AND, the center of the trammel shaft must line up in the middle of the dome bricks to achieve a hemispherical dome.

If your reason for starting with a soldier course is to make a flatter, Neapolitan style oven, I believe your going to need a different trammel set up or make it an adjustable tool, but I'll let others with more experience weigh in on that as well as your floor brick question.

[TEDFB]

I wanted to start building the dome, so on a small dry test I found that on the first brick after the "soldiers "the brick squared off well, but if I square the second brick it leaves a lip on the top of the first brick.
Any ideas
I also layed the floor with a sand clay mix 50 /50 and I found that there are a few bricks that are not solid, (loose)
Would appreciate any input