My IT design

[Dyerema]

After renting a bigger saw. I made the arch fit a bit better

[Dyerema]

[Dyerema]

This is ok for an arch that is never going to be seen I think.

[Dyerema]

Russell. These cuts are made before putting the bricks into the arch?

i can cut the inside. The outside cut doesn’t make sense yet.

It seems to me that it would cut into the face of the bricks in the outside of the arch.

The cuts to rest the dome on are exceedingly challenging. And I wonder if those are better done by hand when the arch is together?

[Dyerema]

[Dyerema]

You can see where I cut the outside of the dome radius and thankfully the vent arch will hide that.

[Dyerema]

[Dyerema]

[Dyerema]

I went in. Studied and contemplated. And “finally got it”

Thanks again for all your support Russel

[UtahBeehiver]

You are not alone, it is a difficult concept to mentally see but once the light bulb comes on the you go "Okay I See". Double check the length of the TDC, it does look a little short, left side of the brick in area should be the longest and most times extends past the front of the arch form. You can take measurements with a pencil on another full size brick and start the pointed double angle side right at the right edge of the new brick.to compare with the one you cut.

[Dyerema]

I think my form is too wide. I will adjust that. The form gets in the way of my IT, so it needs to be a bit narrower. I think TDC brick is correct.

[Dyerema]

I trimmed the bricks all a bit long I think, but will go back and revisit each one for accuracy to my IT.
The IT is really unbelievably important in this whole process.

[UtahBeehiver]

Yes it is and especially an adjustable one.

[Dyerema]

I think a non adjustable should be discouraged. I started my design with a non adjustable and then read that the adjustable was preferable so I redesigned.

[UtahBeehiver]

I always recommend a adjustable one, it is easier to build a non adjustable one (so many head this way) but in the long run it is better to spend the time up front and make the IT adjustable.

On another note, the reason IT gets in the way at TDC, remember the arch form is set at the radius at floor level, IE 21" I think, as you move up the pivot point off the floor starts to come into play, so now your radius starts to increase, say at this point some where around 21" plus 1" +-, then maxing out the top of dome. So you can play with the IT radius while you doing the tapered arch bricks. Also, remember the cuts on the bricks are not the same left to right of TDC, you need to cut each one separate base on the IT and the previous brick cut.