Trammel/ indispensable tool

[This lass builds UK]

Hi all I've made a trammel but soda law my first line of dome bricks built around the oven floor isn't perfectly round. Am I on to use a bit of eye judgement and the trammel to get the angle. To do this I need to move the trammel board depending on which brick I'm working on. Annoying but am I ok to just get the angle with the trammel?

[Kvanbael]

Why oh why didn’t you use your IT (trammel) for the first course. Distance is equally important than angle for getting a nice dome. Here are your options:

1. keep moving your IT base around, getting relativelty smooth brick seams but probably a wobbly overall shape in the end. And a very irregular last course and keystone.

2. fix your IT base now. Continue with a perfect dome for course 3 and onwards and live with the somewhat ugly seam between course 2 and 3.

3. break it all loose. Fix IT base and start over. End up with a nice regular dome.

[This lass builds UK]

Aaahhhh just because it currently looks nice doesn't mean it'll end up looking right! I see that now, I just cut the floor bricks and then placed the first course around them leaving 3mm gap for expansion.
I'm gonna go with option 1, the inside I think will look ok, the outside will be wobbly but hopefully the fibre blanket and exterior render will mitigate the shape. Saying that I might just do 2. Hmmm a thinker. Thanks for your input!